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Recent Advances on Functional Group Interconversion
Guest Editor(s): Teresa M. V. D. Pinho e Melo, Ana L. Cardoso
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Protein Kinases and Their Inhibitors
Current Enzyme Inhibition, Volume 13, Number 2
Guest Editor(s): Satya P. Gupta
"Current Enzyme Inhibition is an important review journal that describes recent developments in enzyme inhibition studies and is of great value to pharmaceutical and medicinal chemists."
Richard B. Silverman
Northwestern Univ., USA
"We are very satisfied by the services of Bentham Science Publishers; due to which we publish the majority of our papers with you.
(Faculty of Pharmacy, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania)
8 Abstract Ahead of Print are available electronically
11 Articles Ahead of Print are available electronically
In continuation to part-1 of the thematic issue titled “Green Chemistry:
Opportunity in Drug Discovery Research” , we are extremely happy to present the
second part of this thematic issue. It would also include the review articles authored by
researchers and academicians from across the world on different synthetic
methodologies developed following the principles of green chemistry.
Humankind has tirelessly engaged themselves in the innovation of new materials
and technologies which could meet their steady demand and provide comfortable
lives. Apart from meeting the basic needs, the advancement in the realm of science
and technologies was indispensable to effectively cope with the challenges of both
natural as well as artificial origin. In particular, chemists have always been passionate
about the synthesis of chemicals of diverse varieties of structurally simple-to-complex nature. These scientific
efforts led to the development of a vast range of compounds having immense importance in the areas of medicinal
and material sciences. Although our scientific endeavor led to the discovery of several lifesaving drugs, natural
products, polymers, and materials that made our life very comfortable and safe, still further investigation needs to
be made, especially in the field of drug discovery in order to overcome the ongoing health crisis also due to
COVID-19 pandemic and such future challenges . The journey towards the synthesis of diverse varieties of
compounds having immense application began as early as in 1828 when Friedrich Wöhler, a German chemist,
first synthesized urea in the laboratory and discarded the vital force theory . Since then, profound development
has been made in the area of synthesis. Some major issues began surfacing that include rapid loss of natural
resources, pollution, and also the safety of the person who is directly or indirectly involved in the development of
any such chemical processes and technology. To overcome these challenges, specifically due to chemical synthesis, concepts of twelve
principles of green chemistry were put forward by Prof. Paul T. Anastas and John C. Warner . These principles mainly focus on the
minimization or complete prevention of waste generation to avoid their deleterious effect on the lives and environment. In addition to that,
other factors such as their storage, disposal, recycling etc., also add to the overall cost of the desired materials. It is important to highlight that
the pharmaceutical industries occupy the top slot in terms of the amount of waste generation. Therefore, greener strategies need to be
developed and employed in the synthesis of several other active pharmaceutical ingredients. To minimize and avoid waste generation, the
importance of the ‘Atom Economy’, a term first introduced by B. M. Trost , was underlined in the second principle, which emphasizes the
maximum incorporation of all the atoms of the reactants into the desired product so that the contribution of the reactants in waste generation
could be avoided. Therefore, the inclusion of reactions with a high % atom economy such as cycloaddition, hydrogenation, carbonylation,
hydroformylation, etc. is highly encouraged, especially in the case of multi-step synthetic schemes. Although other parameters such as
Environmental factor’ or ‘E factor’ introduced by R. A. Sheldon in late 1980 , is also required to assess the greenness of any chemical
reaction as the % value of atom economy doesn’t reflect the contribution of other auxiliary materials to the overall waste generation. It is
important to mention that higher and lower values of % atom efficiency and E factor respectively could not be considered as the primary
parameters to evaluate the efficiency and greenness of a method. Other aspects such as the toxicity associated with the reactants, reagents,
intermediates, and the product formed in the reactions also need to be reviewed while designing any synthetic schemes. Therefore, taking all
these facets into account, the third principle emphasizes ‘less hazardous synthesis of chemicals’ as by reducing the use of hazardous
chemicals, the risk associated with a method can also be minimized or avoided. The fourth principle mainly focuses on the ‘design of safer
chemicals’, which simply means that while attempting to enhance the efficacy of any chemicals, the attention should also be on the
minimization of toxicity. For example, different aspects such as pharmacokinetics, pharmacodynamics, toxicity profile, ADME properties etc.
of a prospective drug molecule could easily be predicted under in silico approach which minimizes the chances of their failure at the later
stages of the trial . Another important aspect that has been underlined in the fifth principle is the safe use of auxiliary substances, which
mainly include solvents or separating agents. Although sometimes the use of solvent becomes indispensable as this influences several
important factors of a reaction such as a homogeneity, mass transfer, reaction temperature, reaction kinetics etc. Despite such an excellent role
of solvents, their adverse impact on the environment and human health has become a matter of serious concern for the past several decades.
Therefore, to address these issues, the development of solvent-free reaction protocols is highly appreciated. In addition, the application of
environmentally benign and safer alternatives such as water, ionic liquid, supercritical CO2, Polyethylene Glycol (PEG), fluorous biphasic
systems have been encouraged . To address the rising energy crisis, the next principle emphasizes on the development of energy-efficient
processes as higher energy consumption contributes towards the higher price of the product and at the same time imposes adverse effect on
the environment. Similarly, to address such energy challenges in the future, designing of reaction protocols employing microwave, UVVisible
radiations, sound wave, electrical energy, etc. are being encouraged as the energy loss could effectively be minimized, which
otherwise would have been lost due to conventional thermal heating for extended time . In addition to the energy, extensive use of nonrenewable
sources such as petroleum-derived chemicals and solvents are posing a greater challenge for the future generation. Therefore, to
achieve the goal of sustainable growth, the seventh principle emphasizes the use of renewable raw materials or feedstock. Some of the best
renewable sources are products that can be derived from plants are cellulose, starch, suberin, lignin, polyhydroxyalkanoates, chitin, lactic
acid, glycerol, and oils . Therefore, the use of this natural renewable livestock may be encouraged. In general, protection and deprotection steps become mandatory in a multi-step reaction scheme which also contributes to the generation of waste materials, energy consumption
which consequently lead to the higher cost of the products. Therefore, if possible, unnecessary derivatization must be avoided . Another
important way of minimizing the excess use of reagents is to employ these in a catalytic amount. Therefore, the ninth principle highlights the
advantages of catalytic methods over the stoichiometric method due to very explicable reasons. As catalytic methods require the substoichiometric
amount of reagents which in general performs better even under mild reaction conditions and also reduces reaction time with
high selectivity. It overall minimizes the amount of waste and energy requirement as well as enhances the atom economy. Chemical
transformations under different categories of the catalytic protocols such as homogenous catalysis, heterogeneous catalysis, biocatalysis, etc.,
have also been explored as greener alternatives to the conventional synthetic approaches. The next principle emphasizes on the development
of degradable chemicals which do not persist in the environment for a longer time. The impacts of these chemicals or their by-products are
very important since they directly or indirectly affect the environment and, ultimately, life existing on the earth. Although chemicals, mainly
polymers such as High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) etc. are being synthesized at a large scale due
to their vast applications at the same time, these chemicals also fall in the category of ‘persistent chemicals’  as these are either nondegradable
or rate of degradation is extremely slow. So, they get accumulated under the soil or create land, water pollution which affects
human as well as animals’ lives. Therefore, the design and development of biodegradable materials using naturally occurring biopolymers
such as starch, cellulose, etc., are being encouraged. In order to avoid the generation of potentially hazardous substances, the application of
advanced analytical tools such as IR, UV-VIS,GC, GC-MS, HPLC, NMR, etc. is being encouraged so that real-time analysis could be
performed.Various different types of monitoring techniques such as in-line (continuous sampling of all material) or online (sampling of
representative aliquots) are available for the proper monitoring of a reaction. The last principle emphasizes the development of the inherently
safer process to avoid or minimize the chances of any chemical accidents such as explosion, fire, or release of any fatal hazardous chemicals
as several accidents such as Bhopal gas tragedy, Chernobyl accident and Flixiborough accidents, etc. are known in the literature where several
people lost their lives either due to the leakage of the toxic gases or due to explosion and fire . In that direction, a very famous quote of
Trevor Kletz, who laid the concept of the Inherently Safer Process (ISP)  says, “What you don’t have can’t leak”. It very clearly means
that while selecting the chemicals, if we have not chosen a chemical or any form of chemical (solid, gas, liquid) which is hazardous or highly
toxic, then the risk of probable accidents taking place due to these chemicals would be very low. Furthermore, research on catalysis to
catalyze a number of fundamental reactions, including 'CuAAC Click-Chemistry' widely useful in drug development, has also been covered
Therefore, in view of the growing need for environmentally benign and safer methods, this second part of the thematic issue titled “Green
Chemistry: Opportunity in Drug Discovery Research” will be highlighting the recent development in the area of green chemistry with a
special focus on their application in the synthesis of pharmacologically important organic scaffolds and drugs. Overall, with these review
articles included in the present thematic issue, various environmentally benign approaches developed and adopted for the synthesis of
medicinally important scaffolds and different other organic transformations have been highlighted. The present thematic issue would be
highly effective in providing information to the readers, in particular researchers, about the eco-friendly and environmentally benign methods
developed in recent years. In 'Green Chemistry: Opportunity in Drug Discovery Research - Part 2', eight prominent research groups actively
engaged in the respective field have diligently presented their overview on some important and emerging aspects of Green Chemistry.
Prof. Victorio Cadierno in ‘Recent Advances in the Transition Metal Catalyzed Addition of Carboxylic Acids to Alkynes’ diligently
presented about the growing impact of the metal-catalyzed hydrofunctionalization of alkynes with various carboxylic acids . In addition
to the assembly of expanded heterocyclic scaffolds through cascade reactions, both the inter- as well intramolecular routes have been
employed to furnish respective enol esters and lactones, which were then further explored to provide the biologically relevant natural product
and their analogues.
Prof. Béla Török and his group in ‘Heterogeneous Metal Catalysis for the Environmentally Benign Synthesis of Medicinally Important
Scaffolds, Intermediates and Building Blocks’ illustrated an excellent, comprehensive and highly useful overview on the growing applications
of diverse solid metal catalysts ranging from common hydrogenation catalysts to metal nanoparticles as green heterogeneous catalysis system
in a thematic order primarily focused on the various reaction types such as hydrogenation, hydrogenolysis, metathesis, oxidation,
hydroformylation, and cross-coupling reactions required for the sustainable synthesis of pharmacologically important molecular scaffolds and
building blocks .
Prof. Ramendra Pratap and his group in “Multi-component reactions for the synthesis of biologically relevant molecules under
environmentally benign conditions” presented an interesting and comprehensive update on multi-component reactions under environmentally
benign conditions such as reaction solvent-free conditions, ultrasound-assisted synthesis, the reaction in aqueous media, and reaction in ionic
liquid as green media widely adopted in academic as well industry for an easy and scalable synthesis of biologically relevant heterocyclic
scaffolds and building blocks greatly explored in drug development .
Prof. Ram Sagar and his group in ‘Exploiting Microwave-Assisted Organic Synthesis (MAOS) for Accessing Bioactive Scaffolds’
presented a nice update on the emerging aspect of microwave-assisted organic reactions to deliver selective and high-yields of a number of
pharmacologically important scaffolds and their impact in future drug discovery program .
Dr. Shiva Rastogi and his group in ‘Photopharmacology of Azo-Combretastatin-A4: Tubulin Polymerization Inhibitors utilizing Green
Chemistry Key Step’ nicely described the emerging concept on photopharmacology with an example of azo-combretastatin-A4 (azo-CA-4), a
natural potent tubulin polymerization inhibitor, where cis-azo-CA-4 (IC50 = 0.2-10 μM) displayed 200-500 times more powerful than transazo-
CA-4 (IC50 = 50-110 μM)and thus potent candidate could be useful in chemotherapy for modern cancer treatment .
Dr. Sharma and co-workers in ‘Advances in the synthesis and antisense technology applications of bridged nucleic acid monomers’
presented an interesting overview about the chemical, chemo-enzymatic, and transglycosylation routes for the expeditious synthesis of
bridged nucleic acid monomers and their analogues with their biological, biophysical and therapeutic applications .Dr. Pintu K. Mandal and his group in ‘One-Pot Glycosylation Strategy for Rapid Access of Oligosaccharides with Wide Range of
Molecular Diversity’brilliantly presented a comprehensive and interesting overview about the growing impact on one-pot stereoselective
glycosylation strategies for an easy and rapid synthesis of the diverse range of biologically relevant complex glycans useful as drug
candidates mainly for the development of sugar-based vaccines and also as emerging diagnostic tools .
At the end, we, Rajkhowa-Kumar-Tiwari, the guest editors of the thematic issue in ‘Room-Temperature Ionic Liquids in Glycoscience:
Opportunities and Challenges’ considered once again a sweet (carbohydrate) chemistry to convey our sincere thanks to all the esteem
contributors, editorial assistant, as well the readers. Carbohydrates are really fascinating scaffolds known for their great impact on drug
discovery and development. The guest editors considered the outstanding features of Room-Temperature Ionic Liquids (RTILs) as a powerful
reaction media and/or catalyst and explored them in various emerging issues in glycoscience, including the dissolution and also
functionalization of diverse carbohydrates to furnish high-yields of biologically relevant sugar-containing molecular scaffolds of wide
We believe that the objective of this thematic issue as claimed to commence a basic and advanced aspect on the emerging relevance of
green chemistry with ample opportunities in academia and industry, particularly in drug discovery and development, is full-filled. We
earnestly thank all the esteem contributors for their excellent contributions and also the reviewers who timely provide their valuable
comments to make the manuscripts even more useful and interesting to readers. Words are insufficient to express our deep sense of
appreciation to Prof. Gyorgy Keglevich, Editor-in-Chief, Current Organic Chemistry for the keen interest and throughout timely support
during the publication of this thematic issue. We also express our sincere thanks to the entire editorial team, notably editorial manager Ms.
Sanober Maqbool and also the language editor, Reference editor, for their timely support in publishing this high standard of publication
volume on ‘Green Chemistry-Part 2’ with 'Current Organic Chemistry', Bentham Science Publications.
Mastering Functional Group Interconversion is an important tool in Organic Chemistry. The ability
to modulate the structure of a given scaffold is essential in any target synthesis and particularly
relevant in areas such as Medicinal Chemistry and Materials Chemistry. The theme issue on Recent
Advances on Functional Group Interconversion provides an overview on selected topics, briefly listed
below, with particular emphasis on recent developments.
Lima, Forezi et al., in “Functional Group Transformation in Naphthoquinones: Strategies for the
Synthesis of Mono- and Bis(Amino-1,4-naphthoquinones)” discuss the functionalization of
naphthoquinone derivatives, a class of compounds known for their activity against several biological
targets. The review focused on the synthesis of aminonaphthoquinones from 1,4-naphtoquinone
derivatives (1,4-naphthoquinone, juglone, lawsone, lapachol, menadione and 2,3-dihalo-1,4-
naphthoquinones) as well as on further transformations of aminonaphthoquinones. Data regarding the biological activity of
some of the naphthoquinone derivatives is also included .
Pinho e Melo et al., in “Reduction of Oximes and Hydrazones: Asymmetric and Diastereoselective Approaches” report on
the most relevant contributions on this topic, published in the last decade. The enantioselective and diastereoselective reduction
of oximes and hydrazones is presented as a versatile synthetic strategy towards chiral amines, which are valuable building
blocks in organic synthesis. The synthesis of hydroxylamines and hydrazines is also covered. The synthetic methodologies use
to carry out these transformations are mainly metal-catalyzed hydrogenation/hydrogenolysis reactions, hydride donor reactions
and electrochemical reactions .
Maria Manuel Marques et al., in “Toolbox for α-amination Reactions” discuss the most recent protocols for α-amination of
carbonyl compounds selected on the basis of synthetic utility, novelty and enantioselectivity. This comprehensive review
covers the construction of the C–N bond between the α-position of a carbonyl and an amine using umpolung strategies in the
ketone moiety and nucleophilic nitrogen sources, using the reaction of ketones/enolates with electrophilic nitrogen sources as
well as via oxidative methodologies .
The theme issue ends with a very interesting review by Marcus Baumann et al., on “Functional Group Interconversion
Reactions in Continuous Flow Reactors”. The review describes key examples from the last decade of various functional group
interconversion reactions carried out under continuous-flow conditions. The selected examples highlight the advantage of this
modern and sustainable synthetic technology regarding safety, efficiency, reproducibility and scalability .
As Guest Editors, we would like to acknowledge all authors for providing excellent reviews and making the publication of
this thematic issue possible.
Csp2-H bonds of (hetero)arenes are often considered ‘un-functional groups,’ and the common representation of organic
structures with ‘invisible’ hydrogens reflecting both their ubiquitous nature and lack of reactivity . Despite this, it has long been a
goal of chemists to selectively transform carbon-hydrogen bonds into new carbon-carbon or carbon-heteroatom bonds . Today, a
wide variety of Csp2–H functionalization methods are available , and such methods are particularly relevant in drug discovery,
where the generation of a large number of analogues to explore structure-reactivity relationships or improve their physicochemical
properties are significant aspects.
The concept of using the functionalization of C-H bonds to obtain several analogues of a complex molecule in the last synthetic
stage was first proposed in 1973 by Breslow and co-workers , but only recently, with the development of C-H functionalization
protocols with impressive functional group tolerance and site selectivity and the recent renaissances of photoredox catalysis and
radical chemistry that have facilitated difficult and previously inaccessible bond-forming reactions under mild conditions, the Late-
Stage Functionalization (LSF) strategy can be widely applied in drug discovery [5-7].
This thematic issue thereby aims to summarize and discuss some successful examples in this research area. Three eminent research groups in the field of
C-H functionalization have kindly accepted my invitation to participate in this special issue by providing an overview on the recent advances on selected topics,
which are briefly listed below, along with the contribution of my own research group:
Prof. Muzart and Dr. le Bras in “Pd-catalyzed Intermolecular Dehydrogenative Heck Reactions of Six-membered Heteroarenes” summarize the results
published since 2010 on the dehydrogenative alkenylation (discovered by Fujiwara and co-workers in 1967) involving Csp2-H bonds of six-membered
Prof. Schumacher and Prof. Godoi et al. in “Regioselective C-H Selenylation of Heteroarenes Under Metal-free Conditions” comprehensively summarize
the studies on the direct Csp2-H selenylation of heteroarenes under metal-free conditions, which represents one of the most powerful synthetic strategies for the
preparation of this synthetically useful selenium-containing compounds .
Dr. Ronchi et al. in “F-based small group decoration of heteroarenes via C-H activation: Medicinal Chemistry rationale and late-stage synthetic methods”
introduce the small F-containing groups, such as CF3, CF2H, OCF3, via the Csp2-H functionalization of heteroarenes using synthetic procedures such as the
Minisci reaction and photochemical or electrochemical C-H activation protocols. They also analyze the rationale behind the use of fluorinated groups in
medicinal chemistry and highlight the methods that can be used for last-stage functionalization .
Prof. Bellina. et al. in “Undirected, Selective Csp2-H Alkynylation of Five-membered Heteroarenes” discuss the results reported in the literature for the
regioselective Csp2-H alkynylation of five-membered heteroarenes without employing orienting groups. Procedures that involve the use of 1-haloalkynes (the
so-called inverse Sonogashira reaction) or analogues or that require terminal alkynes via cross-dehydrogenative coupling are discussed .
As Guest Editor, I would like to appreciate all the authors for their valuable contributions and all the referees for their excellent work in reviewing the
I am also grateful to the Editor-in-Chief, Prof. György Keglevich, and the Editorial Manager, Ms. Sanober Maqbool, for their kind support in preparing this
The synthetic approaches towards the development of different varieties of organic
molecules of potential medicinal interest have taken a paradigm shift in the last few
decades. In contrast to the conventional approaches in the organic synthesis, where
achieving the best reaction yield of a target, the molecule was the prime focus without
paying much attention towards the impact of the synthetic methodology adopted for it,
on the Safety, Health, and Environment (SHE), the development of environmentally
benign and green synthetic reaction protocols and technology is the principal goal in
the present scenario [1-3]. In that direction, the development of the concept of 'Green
Chemistry' and its twelve basic principles by Prof. Paul T. Anatsas and Prof. John C.
Warner work well as a promising guiding tool for the synthetic and medicinal chemist
. The prevention or minimization of waste generation, increasing % atom economy,
decreasing environmental factors (E Factor), catalysis, efficient use of energy, etc., are some of the notable key
points of the basic green chemistry principles . The applications of cost-effective, safe, easy, straight-forward,
high-yielding, selective (regio-, chemo-, and sterero-), sustainable, and environmentally benign approaches for
generating drug candidates or potent scaffolds that fulfill the “green chemistry” principles are incredibly
imperative . Toward this end, this thematic issue presents a judicious endeavor to communicate the impact of
'Green Chemistry' in particular to their opportunity in drug discovery & development to the readers.
In this thematic issue titled “Green Chemistry: Opportunity in Drug Discovery Research,” the development of
common practical synthetic methodologies which are in accordance with the principles of green chemistry
towards achieving the various types of organic transformations is widely covered. In particular, the application of
green and eco-friendly reaction protocols for the synthesis of pharmacologically important organic scaffolds has
been highlighted. This issue covers sixteen different topics (divided into two separate parts with eight manuscripts
in each section) that would widely illustrate the scope of green chemistry in various aspects of sustainable synthetic strategies including,
reactions in ionic media , aqueous condition , solvent-free condition , non-conventional energy source like microwave condition ,
ultrasonic condition , visible-light-induced condition , one-pot multi-component condition , biocatalysis , organocatalysis ,
heterogeneous catalysis , click condition [16, 17], etc. towards the development of pharmacologically active new chemical entities
(NCE's) widely explored in drug discovery research. Total sixteen leading groups who are very active in their field have kindly accepted our
invitation to participate in this thematic issue by providing an overview on the recent advances on selected emerging topics on green
chemistry and contributed to this COC venture; for that, we are grateful to them for their excellent contributions. In 'Green Chemistry-Part 1
issue,' eight eminent research groups in the field of sustainable chemistry have briefly presented their overview listed as follows:
Prof. Pellissier in 'Organocatalytic Asymmetric Tandem/Domino Reactions Towards Access to Bioactive Products' introduced a nice and
interesting overview on major developments on powerful enantioselective organocatalytic asymmetric catalysis including Michael-initiated-,
aldol-initiated and other domino reactions as the key steps to produce high yields of important intermediates as well as biologically relevant
simple-to-complex molecular architectures .
Prof. Keglevich et al., in "Synthesis of Phosphonates, Phosphinates and Tertiary Phosphine Oxides by Pd- or Ni-Catalyzed Microwave-
Assisted P–C Coupling Reactions without the Addition of Conventional Ligands" presented a typical and useful overview on microwave
(MW)-induced effective tool applied for the P–C coupling reactions of vinyl/aryl halides with dialkyl phosphites in the presence of an
appropriate Pd- or Ni- catalyst . In addition to the mechanistic details to establish the optimum reaction conditions, the authors also
provide the factors affecting the activity of the catalyst to form complex as well the reactivity of the reactants in the P–C coupling reactions.
Also, this powerful protocol displayed a nice expansion of the reagents and catalysts predominantly for the simplification of the catalytic
system to be considered as the 'environmentally benign tool' .
Prof. Matsumura and his group in 'Oxidized Polysaccharides as Green and Sustainable Biomaterials' considered the notable non-toxic,
biocompatible, sustainable, and bioavailability nature of carbohydrates and described the general consideration of oxidized polysaccharidebased
candidates useful for their various emerging applications in the area of biomaterials and biomedical sciences .
Prof. Girija Singh in 'Greener Approaches to Selected Asymmetric Addition Reactions relevant to Drug Development' presents an
interesting aspect of environmentally benign parameters (i.e., a reaction in greener solvents like aqueous media or reaction under solvent-free
conditions or reaction at room temperature or reaction under non-conventional energy source, etc.) in a number of asymmetric addition
reactions (e.g., aldol reaction, Michael addition, aza-benzoin reaction, and Mannich reaction) to produce a wide range of biologically relevant
molecular scaffolds .
Prof. Diganta Sarma and his group in 'Synthesis of Medicinally Relevant Scaffolds-Triazoles and Pyrazoles in Green Solvent Ionic
Liquids' nicely explored the emerging scope of modular 'Click Chemistry' to produce biologically potent regioselective triazole analogues
under green conditions via reaction in ionic liquids . The authors also present a few selected and practical syntheses of pharmacologically
active pyrazole heterocycles using ionic liquid as suitable reaction media.
Prof. Brahmachari et al., in 'Ultrasound-Promoted Organic Synthesis - A Recent Update' considered the inherent properties of
ultrasonication to minimize wastes as well as to reduce energy or reaction time and nicely presented an interesting overview on ultrasoundpromoted
organic transformations involving both C-C, C-N, C-O, and C-S bond-forming reactions .
Prof. Ghanshyam Bez and his group in 'Application of nature’s chiral pool in environmentally sustainable organic synthesis' brilliantly
presented emerging applications of nature’s chiral pool as suitable catalysts, solvents, or raw materials (e.g., carbohydrates, amino acids, and
their readily accessible derivatives) for easy access of a diverse range of biologically active molecular scaffolds .
In the end, Mukherjee et al. in "Mutasynthesis of Medicinally Significant Natural Products Through Manipulation of Gene Governing
Starter Unit," introduced a nice overview on the impact of mutasynthesis as a powerful tool in the development of a number of interesting,
complex microbial secondary metabolites of biological relevance .
The main objective of this thematic issue was to introduce a concept of multi-disciplinary opportunity with a critical discussion about the
diverse emerging relevance of green chemistry in drug discovery and development. Thus, the topics included in the basic and advanced
aspects of green chemistry may be useful in academia and industry. We sincerely thank all the contributors who are eminent scientists
actively engaged in various emerging aspects of green chemistry/organic synthesis/medicinal chemistry. Furthermore, words are insufficient
to express our special thanks to all the learned reviewers who provide constructive comments and suggestions to make the manuscripts even
more interesting to readers and useful for researchers actively working on diverse fields of interest, particularly sustainable chemistry, green
chemistry, organic synthesis, and drug development.
Last but not least, we also express our deep sense of appreciation to Prof. Gyorgy Keglevich, Editor-in-Chief, Current Organic Chemistry,
and the entire editorial team notably, Ms. Nuzhat Gul and editorial manager Ms. Sanober Maqbool for their keen interest and throughout
timely support in publishing this thematic issue with the high standard of publication maintained in bringing out this volume on ‘Green
Chemistry-Part 1’ with 'Current Organic Chemistry,' Bentham Science Publications.
Cancer has killed more people in the world than all major wars taken together. A number of interventions and
disease management approaches have been undertaken. These approaches include chemotherapy, radiation
therapy, immunotherapy, hormone therapy, gene therapy or targeted therapy . In some cases, surgery in
addition to any of the above approaches is also recommended. In a fight against cancer through medication,
organic and medicinal chemists have come out with a number of drugs, majority of which are based on
heterocyclic compounds. The success of these efforts can be gauged from the fact that numerous drugs based on
heterocyclic motifs have either reached the market or are in advanced stages of clinical trials . The gargantuan
library of heterocyclic compounds is there to explore and experiment and more often than not, it has given
unparalleled results with each passing year. The most prominent heterocyclic moieties with anticancer compounds
include quinazoline derivatives, indole derivatives, thiazole and 4-thiazolidinone containing heterocyclic
compounds, flavonoids, polyphenolic compounds, azoles and benzimidazoles to name a few. The azole based compounds deliberated as
anticancer drugs effectively bind to the target proteins and enzymes via non-covalent interactions . Heterocyclic anticancer agents are
known to act by targeting various enzymes or receptors, including (HDACs), sirtuins, PIM kinases, DNA topoisomerases, and σ receptors .
They are effective against a number of different types of carcinomas with encouraging results. Some of such heterocycles approved recently
by FDA for different types of gliomas include alectinib, apalutamide, etoposide and pexidartinib. The structural similarity of amino
derivatives of benzimidazole with purines makes it a fascinating nucleus for the development of anticancer agents. There is a direct
relationship between anticancer activity and the chemical functionalities around benzimidazole nucleus . Quinazolines act as kinase
inhibitor for EGFR mutation and exhibit antiproliferative activity . Several quinazoline derivatives have been approved by FDA for clinical
use as anticancer drugs. These include gefitinib, erlotinib, lapatinib, afatinib, and vandetanib. These agents act through different mechanisms
such as inhibition of tyrosine kinase, inhibition of human epidermal growth factor receptor-2 (HER2/neu) and epidermal growth factor
receptor (EGFR) pathways. . The synthesis and isolation of numerous novel anticancer agents of natural origin have also gained
momentum over the past years. Indole based alkaloids like vincristine, vinblastine, vinflunine, and vinorelbine derived from the plant
Catharanthus roseus are popular anticancer drugs. They owe their anticancer activity to their ability to dissolve the mitotic spindles and cell
division resulting from the microtubule disruption . The polymerization of tubulin is the main target in most of the indole-based
compounds . Similarly, flavonoids are polyphenolic compounds derived from fruits and vegetables and also present in plant-derived
beverages like wine, green tea, and cocoa-based products. A number of flavonoids that have been reported to exhibit potent anticancer
properties in animal studies have been further screened for their safety and efficacy in humans . They are known to exert anticancer effect
via different mechanisms such as carcinogen inactivation, antiproliferation, cell cycle arrest, induction of apoptosis and differentiation,
inhibition of angiogenesis, anti-oxidation and reversal of multidrug resistance or a combination of any two or more of these mechanisms .
Irrespective of their natural or synthetic origin, anticancer agents based on heterocycles are an important tool in the fight of mankind against
Catalysis is an enormous field, encompassing everything from the study of
fundamental physical properties to genetically engineered chemical-producing
microorganisms. Thus, catalysis is the area of chemistry that has a tremendous impact
on society. It is fundamental to numerous endeavors such as making consumer products
we use every day, producing the drugs that keep the population healthy, helping
agriculture feed the planet, breaking down environmental pollutants in air and water,
and generating, storing and converting energy. The production of chemicals through
catalytic processes accounts for approximately 25% of the industrial energy [1-8].
Hence, this issue represents the articles that contributed to the field of organic
transformation using heterogeneous catalysts. The present issue includes three review
articles contributed by eminent research groups involved in this prominent field of organic chemistry. It provides up-to-date developments in
Dr. Pratap Singh et al. in “Carbon Nanocomposites: The Potential Heterogeneous Catalysts for Organic Transformations” reviewed the
synthesis of carbon-based nanocomposites and discussed its applications as a heterogeneous catalyst for various organic transformations such
as oxidation, hydrogenation, coupling, and multi-component reactions .
Dr. Singh et al. in “Use of Bimetallic Nanoparticles in the Synthesis of Heterocyclic Molecules” comprehensively summarized the list of
names of plants that were used for the synthesis of bimetallic nanoparticles. In this review, the authors also discussed the application of
bimetallic nanoparticles for the synthesis of the heterocyclic molecules containing one, two, and three nitrogen atoms in the ring .
Dr. Mohammadi Ziarani et al. in “The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous
Catalyst in Organic Synthesis” depicted the dual nature of functionalized mesoporous silica SBA-15 for different types of organic reactions.
The authors also showed the plausible mechanism for the synthesis of organic compounds such as 4-aryl-methylene isoxazole-5(4-H)-ones, 3-
As guest editors, we would like to appreciate all the authors for their valuable contributions and all the referees for their excellent work in
reviewing the submitted manuscripts. We are also grateful to the Editor-in-Chief Prof. György Keglevich and the Editorial Manager Ms.
Sanober Maqbool for their kind support in preparing this thematic issue.
To design various structurally diverse molecular entities, carbon-carbon and carbon-heteroatom bond-forming
reactions have been regarded as the most significant tools among many others [1, 2]. A variety of carbon-carbon
or carbon-heteroatom bond-forming strategies are being designed for the synthesis of a large number of
commercially available drug molecules, bioactive heterocycles, pharmaceuticals, agrochemicals, hormones,
vitamins, dyes, pigments, etc. Constant efforts have been made to make these versatile tools more effective and
sustainable by developing new methods or modifying existing protocols [3, 4]. As a result, a huge number of
methods are being reported almost every day related to carbon-carbon and carbon-heteroatom bond formation
under greener conditions [5-15]. This thematic issue titled ‘Carbon-Carbon and Carbon-Heteroatom bond-forming
reactions under greener conditions’ has been focusing on some of the recent carbon-carbon and carbon-heteroatom
bond forming strategies with special emphasis on greener aspects.
The first part of this thematic issue was published in two separate parts i.e. Part-1A which was constructed with five important review
articles [16-20] and Part-1B compiled with three valuable review articles [21-23]. Under the same direction, this present thematic issue i.e.
Part-2 represents six valuable review articles contributed by the eminent research groups. This special issue highlights up-to-date literature on
the following six selected topics:
The first contribution of this thematic issue titled ‘A Review of Recent Advances in the Green Synthesis of Azole- and Pyran-Based
Fused Heterocycles using MCRs and Sustainable Catalysts’ by Kerru et al. describes the synthesis of various azole/pyran annulated
heterocycles by following carbon-nitrogen or carbon-oxygen bond forming strategies via one-pot multi-component reactions using
environmentally benign sustainable catalysts .
The second contribution titled ‘An Updated Coverage on Synthesis of Benzo[b]thiophenes via Transition-Metal-Catalyzed Reactions: A
Review’ by Ejaz et al. summarizes handful literature related to the facile and convenient synthesis of structurally diverse benzo[b]thiophene
derivatives using various transition metals as catalysts .
Use of hypervalent iodine reagents is one of the fascinating areas of today’s research. The third contribution titled ‘Formation of Carbon-
Nitrogen Bond Mediated by Hypervalent Iodine Reagents Under Metal-free Conditions’ by Yang et al. highlights the latest developments on
various types of carbon-nitrogen bond formations involving hypervalent iodine reagents under metal-free reaction conditions .
Recently, dihydro[1,3]oxazine derivatives have gained significant attention due to their huge biological applications. The fourth
contribution titled ‘Syntheses, Biological and Material Significance of Dihydro[1,3]oxazine Derivatives: An Overview’ by Lathwal et al.
describes various synthetic strategies, detailed biological evaluation and material significance of a series of dihydro[1,3]oxazine derivatives
Quinoline and its derivatives have been found to possess a wide range of biological activities. A large number of methods were designed
for the synthesis of these biologically significant scaffolds under various reaction conditions. The fifth contribution titled ‘Facile Synthesis of
Quinolines in Water’ by Borah et al. compiles the latest developments on aqueous-mediated synthesis and fictionalization of various
quinoline derivatives .
Last decade has shown huge applications of sulfonic acid functionalized calix[n]arenes as an efficient, metal-free, commercially available,
low-cost organocatalyst for various organic transformations. In the last contribution titled ‘p-Sulfonic Acid Calix[n]arene Catalyzed Synthesis
of Bioactive Heterocycles: A Review’, we have demonstrated the catalytic applicability of p-sulfonic acid calix[n]arenes as an efficient
organocatalyst for the synthesis of various biologically promising scaffolds .
I am very much thankful to all the contributors for their valuable efforts to build up this special thematic issue for Current Organic
Chemistry (COC). I am grateful to the senior journal manager and the entire editorial team of Current Organic Chemistry, specially Ms.
Sanober Maqbool and Ms. Nuzhat Gul for their continued support. No words are sufficient to express my gratitude to Prof. (Dr.) Gyorgy
Keglevich (Editor-in-Chief) for continued support and guidance. I am also thankful to the respective reviewers for their efforts and
suggestions to improve the quality of this special issue.
The recent interest in the synthesis of a wide range of functionalized biologically active molecules was driven
by the ever growing demands of the pharmaceutical industry [1-3]. The synthesis of complex molecules with
different active pharmacophores has been achieved by adopting tailored synthetic approaches. The traditional
methods for the synthesis of biologically active molecules have several drawbacks, including multi-step
approaches, low isolated yields, longer reaction times, tedious purification procedures, employing toxic catalysts
and reagents, and harsh reaction conditions [4-6]. To avoid such drawbacks, different modern synthetic strategies
have been recently developed for the synthesis of bio-active molecules. Among these, one-pot multicomponent
reactions, C-H activation reactions, nanocatalysis, mechanochemical reactions using ball milling, microwave
assisted synthesis, visible light assisted photocatalytic reactions, and sonochemical organic synthesis have
attracted great attention for clean organic synthesis. The fast and growing developments in this field are
overwhelming, and call for special efforts to collect relevant information for the benefit of academics and individuals involved in the
pharmaceutical industry. This thematic issue is dedicated to highlighting the modern progress in developing various strategies for the
synthesis of bio-active molecules, with special emphasis on greener synthesis routes [7-12].
The present issue includes eight review articles contributed by eminent research groups involved in this prominent organic chemistry
field, which provide up-to-date developments in selected topics. In summary:
The first contribution titled ‘Microwave: A Green contrivance for the Synthesis of N-Heterocyclic Compounds’ by Lambat et al.
highlights the microwave mediated catalytic reactions used for the synthesis of a diversity of N-heterocycles by multi-component reactions
(MCRs) and a variety of miscellaneous reactions. The review also addresses some aspects of the use of nanoparticles for a diversity of
applications in microwave chemistry .
The second contribution titled ‘Methods and Strategies Used in Green Chemistry: A Review’ by Pottoo et al. summarizes the literature
associated with the development of various compounds and greener techniques such as ultrasound-assisted method, microwave-assisted
method, green solvent reactions, solvent free reactions, biomolecules and nano-formulations as new safe approaches .
The third contribution, titled ‘Review on Synthesis of Bio-Active Coumarin-Fused Heterocyclic Molecules’ by Banerjee et al., describes
the various methods for synthesizing different classes of coumarin-fused heterocyclic molecules and their applications in chemical, optical,
pharmaceutical and other useful applications .
The fourth contribution titled ‘CO Surrogates: A green Alternative in Palladium Catalyzed CO Gas Free Carbonylation reactions’ by
Ahmed Abdala and Lambat et al. addresses the recent developments in palladium-catalyzed carbonyl insertions without the direct use of
gaseous CO .
The fifth contribution, titled ‘Recent Advances in On-Water Multicomponent Synthesis of Coumarin Derivatives’ by Penta et al.
addresses the one pot multicomponent synthesis of structurally diverse coumarin scaffolds in water as an efficient and green medium .
The sixth contribution titled ‘Palladium-Catalyzed Cascade Reactions for Annulative π-Extension of Indoles to Carbazoles through C-H
Bond Activation’ by Jana et al. is concerned with the survey of recent literature on palladium-catalyzed π-extension of indole to carbazole
moiety through C-H bond activation .
The seventh contribution titled ‘Modern Progress in Iron-Catalyzed Reactions towards the Synthesis of Bioactive Five- and Six-
Membered Heterocycles’ by Adak et al. discusses the catalytic applicability of iron and its derivatives for various organic transformations and
the synthesis of biologically active five and six membered heterocyclic compounds .
The last contribution, titled ‘Green Approaches for the Synthesis of Indole Derivatives and their Pharmaceutical Applications: Last Ten
Years Developments’ by Das et al. discusses the various synthetic methods for the preparation of structurally diverse indole scaffolds using
green chemistry and their pharmaceutical relevance .
As Guest Editors, we would like to appreciate all the authors for their valuable contributions and all the referees for their excellent work
in reviewing the submitted manuscripts. We are also grateful to the Editor-in-Chief Prof. György Keglevich and the Editorial Manager Ms.
Sanober Maqbool for their kind support in preparing this Thematic Issue.
Synthetic peptides and amino acids are important sources for developing new drugs, because they have low
toxicity and specificity, are less prone to side effects, and have the advantage of being low-cost. However,
peptides and amino acids have some limitations from the pharmacological point of view, because of their low
residence time in the body and low effective concentration at the site of action, which is mainly due to factors such
as susceptibility to enzymatic degradation, rapid elimination, and low ability to penetrate across membranes [1-3].
The bioavailability and bio-distribution of peptides and amino acids in the body can be improved by chemical
modification. In this context, chemical synthesis can allow obtaining linear, cyclic, polyvalent, and chimeric
peptides, among others. In addition, peptide biological activity can be enhanced by incorporating unnatural amino
acids, steroids, hormones, organometallic compounds, carbohydrates, lipids, antibiotics, organic compounds,
inorganic compounds, etc. This functionalization can be performed directly on the peptide or on the amino acids
that generate the building blocks that are conjugated with these molecules, which can then be used as precursors in order to obtain the
peptides and proteins [4-8].
This thematic issue is a review of the synthetic approaches developed over the last few years for enhancing the biological activity of
promising peptide sequences. Researchers with recognized expertise in organic synthesis as a tool for the development of molecules for
biomedical applications participated in preparing the issue. A brief description of each of these contributions is given below.
In the manuscript entitled “The Role of αvβ6 Integrin Binding Molecules in the Diagnosis and Treatment of Cancer”, Dr. Urquiza, et al.
describe the importance of integrin in cancer treatment and discuss peptides, recombinant proteins, non-peptide molecules, and αvβ6-
antibodies that specifically bind to αvβ6-integrin. In addition, the biological properties and possible uses of these molecules in cancer imaging
and therapy are described since the αvβ6-integrin is over-expressed in most tumor cells .
In the manuscript entitled “Resorcinarenes: Generalities and Their Role in the Modification and Detection of Amino Acids”, Dr.
Maldonado, et al. present a valuable review of the properties and characteristics of resorcinarenes, as well as the main synthetic routes used
to form amino acid-conjugated macrocycles that could have multiple applications in the pharmaceutical sciences, engineering, and medicine
In the manuscript entitled “Ferrocene and organotin (IV) conjugates containing amino acids and peptides: a promissory tool for searching
for new therapeutic and diagnostic tools”, Dr. Farfan, et al. describe the synthesis strategies used for the preparation of amino acids and
peptides containing ferrocene or organotin (IV) derivatives. In addition, the antibacterial and/or anti-cancer properties of these organometallic
compounds are summarized .
In the manuscript entitled “Designing short peptides: a Sisyphean task”, Dr. Rivera, et al. review the synthetic approaches and strategies
used to design short peptides, highlighting the achievements, limitations, and advantages of each method. The advantage of short peptides lies
in their stability, ease of production, safety, and low cost, as well as their biomedical and industrial applications .
In the manuscript entitled “Development of strategies for glycopeptide synthesis: an overview on the glycosidic linkage”, Dr. Garcia, et
al. present a review of the chemical synthesis of glycoconjugates in solution and/or solid phase. Several methods for the synthesis of
glycosylated amino acid derivatives and/or glycopeptides and their use as drugs to mitigate the impact of microbial resistance and/or cancer
are described .
In the manuscript entitled “Electrochemical Detection of Neurotransmitters in the Brain and Other Molecules with Biological Activity on
the Nervous System”, Dr. Bustos, et al. describe the electrochemical techniques used for in vitro or in vivo detection of neurotransmitters and
other molecules with biological activity at the level of the central nervous system, as a contribution to the diagnosis of neurological diseases
In the manuscript entitled “Bio-organometallic Peptide Conjugates: Recent Advances in their Synthesis and Prospects for Biomedical
Application”, Dr. Guzman, et al. review synthetic strategies for obtaining organometallic peptides and amino acids containing ferrocene,
rutenocene, cimantrene, or osmocene. The authors describe SPPS and/or click chemistry-based methods used for obtaining organometallic
compounds that could be used to develop a new generation of antimicrobial and chemotherapeutic drugs .
Finally, as Guest Editor of this issue, I would like to express my thanks to all the authors for their high-quality manuscripts and to the
reviewers for their time and effort in providing constructive critiques in order to guarantee the excellence of this issue. I am also thankful for
the logistical assistance of Ms. Sanober Maqbool, Editorial Manager, during the submission and review procedures.
This Special Issue covers the hot topics on recent synthetic interest in halogen and related
chemistry as well as the unique characteristics of halogen compounds. The excellent reviews by the
experts and eminent researchers engaged in the recent advances, i.e., preparations, reactions, and
mechanistic studies of unique organohalogen compounds, halogen bond interaction as the catalysis,
and halogen-controlled unique reactions for synthesizing useful organic molecules, such as
pharmaceutical compounds and organic materials, are provided in this Special Issue.
Carbon-carbon and carbon-heteroatom bond-forming reactions are the most important tools for the syntheses of structurally
diverse molecular entities . Various drug molecules, bioactive heterocycles, agrochemicals, dyes, pigments, pharmaceuticals,
vitamins, hormones and other useful organic substances are being synthesized via these carbon-carbon and carbon-heteroatom
bond-formation strategies. Therefore, under these environmentally conscious days, constant efforts have been made to design
new methods or modify existing protocols for such bond-forming reactions to make them sustainable [2, 3]. As a result, the last
decade has shown a tremendous outburst to carry out carbon-carbon and carbon-heteroatom bond-forming reactions under
environmentally benign and sustainable conditions [4-10]. The thematic issue ‘Carbon-Carbon and Carbon-Heteroatom Bond-
Forming Reactions Under Greener Conditions’ is aimed to highlight some of the recent developments In carbon-carbon and
carbon-heteroatom bond forming reactions with special emphasis on greener aspects.
The first part of this thematic issue, i.e., part-1A included five significant review articles [11-15]. The present part of this
thematic issue, i.e., part-1B is composed of three valuable review articles contributed by the eminent research groups working
on this fascinating field of organic chemistry. This part of the special thematic issue offers up-to-date literature on the following
three selected topics:
The first contribution of this part of the thematic issue titled ‘Green Chemistry Approaches to the Synthesis of Coumarin
Derivatives’ by Molnar et al., describes various green synthetic approaches for the synthesis of diverse coumarin derivatives
The second contribution, titled ‘Construction of Carbon-Carbon and Carbon-Heteroatom Bonds: Enabled by Visible Light’
by Mondal and Mukhopadhyay, summarizes the literature associated with the recent advancements on green visible lightmediated
carbon-carbon and carbon-heteroatom bond-forming reactions .
In the last contribution titled ‘Formation of Carbon-Carbon Bonds Mediated by Hypervalent Iodine Reagents Under Metalfree
Conditions’, Prof. Du and his research group highlight the recent advancement in the construction of carbon-carbon bonds
utilizing hypervalent iodine reagents under metal-free condition .
I am grateful to all the contributors for their valuable efforts to organize this part of the special thematic issue for Current
Organic Chemistry (COC). I am very much thankful to the senior journal manager and the entire editorial team of Current
Organic Chemistry, specially Ms. Sanober Maqbool and Ms. Nuzhat Gul, for their continued support. No words are sufficient
to express my gratitude to Prof. (Dr.) Gyorgy Keglevich (Editor-in-Chief) for his unconditional help and encouragement. I am
also thankful to the respective reviewers for their efforts and suggestions to improve the quality of this special thematic issue.
Carbon-Carbon and Carbon-Heteroatom Bond-forming Reactions under Greener
The Chemistry of Allenes
Nowadays, environmental pollution/deterioration and greenhouse effect are becoming increasingly prominent, primarily due
to the dependence and overuse of fossil source [1, 2]. As a result, the development of green and sustainable approaches has
become a particularly important theme in recent years [3-5]. Organic synthesis is a versatile tool in the design and creation of
desirable scaffolding molecules, while the processes of which typically involves toxic and non-renewable starting materials as
well as the formation of waste or by-products . Biomass, on the other hand, is considered as the most abundant organic
carbon resource for producing liquid fuels and value-added chemicals through an array of cascade chemocatalytic reactions [7-
10]. The exploration of robust and green technologies is accordingly being deemed to be one of the vital and promising means
for biomass valorization and relevant organic transformations.
This thematic issue thereby aims to survey the development of green technologies for catalytic upgrading of biomass
feedstocks, and provides a glimpse into successful examples in this research area. Five eminent research groups in the field of
biomass valorization have kindly accepted our invitation to participate in this special issue by providing an overview on the
recent advances on selected topics briefly listed as follows:
Dr. Chen et al. in “Lignin Reactions and Structural Alternations under Typical Biomass Pretreatment Methods” introduce
typical pretreatment methods such as hydrothermal pretreatment, alkaline pretreatment, biodegradation, and oxidative
pretreatment, with their corresponding impacts on the lignin structures and reactions .
Dr. Lin et al. in “Chemoselective Hydrogenation of Biomass-derived 5-hydroxymethylfurfural into Furanyl Diols”
comprehensively summarize the studies on the chemoselective hydrogenation of 5-hydroxymethylfurfural into furanyl diols in
terms of different H-donors, including molecular H2, alcohols, formic acid and other alternative H-donors, and also provide
future research direction on the production of furanyl diols .
Dr. Li et al. in “Alcohol-mediated Reduction of Biomass-derived Furanic Aldehydes via Catalytic Hydrogen Transfer”
depict alcohol-mediated reduction of biomass-derived furanic aldehydes via catalytic hydrogen transfer, also with attention on
the representative reaction mechanisms and selective control of product distribution .
Dr. Liu et al. in “Catalytic Hydrogenolysis of Biomass-derived Polyhydric Compounds to C2–C3 Small-molecule Polyols: A
review” describe the catalysts and catalysis for selective hydrogenolysis of these polyhydric compounds to C2–C3 polyols, and
outline the reaction pathways with the state-of-the-art technologies for the target polyol formation based on the C3, C5, and C6
polyhydric alcohol hydrogenolysis .
Dr. Yang et al. in “Chemo-catalytic Esterification and Transesterification over Organic Polymer-based Catalysts for
Biodiesel Synthesis” discuss catalytic valorization of sustainable feedstocks into biodiesel via transesterification and
esterification reactions mediated by functionalized organic polymers-based catalysts, with special emphasis on the synthetic
routes to the versatile organic polymers-based catalytic materials .
As Guest Editors, we would like to appreciate all the authors for their valuable contributions and all the referees for their
excellent work in reviewing the submitted manuscripts.
We are also grateful to the Editor-in-Chief Prof. György Keglevich and the editorial manager Ms. Sanober Maqbool for
their kind support in preparing this thematic issue.
Waste-to-valuable products are being considered as one of the best solutions to convert the waste biomass into green and
environment-friendly products. The wide utilization of waste biomass as a potential source of fuels, power, recycled materials,
valuable chemicals are well recognized globally. The waste driven fuels are used in all sectors of society for production of
electricity, transport fuel, heating and cooling source, and for industrial processes. These fuels not only solve the waste disposal
issues but also generate enormous economic and environmental benefits. They are promising alternatives due to their
renewable, sustainable and eco-friendly features. However, there are multiple challenges in conversion and efficient utilization
of waste biomass into sustainable energy and fuels .
The purpose of the special issue, titled “Waste Biomass Utilization for Value-added Green Products” is to focus on the best
possible ways to convert the waste biomass into value added and renewable products with an ambition to highlight the recent
trends targeting the challenges and opportunities in this area. Renowned researchers have accepted our invitation to contribute
their articles on the below subtopics;
Conversion/Utilization of Waste Biomass Feedstocks into Fuels: The aspects of discovery and utilization of different waste
biomass feedstocks for generation of various fuels. The examples of such waste biomass to fuels systems include the bioalcohols,
biodiesel, biogas, biohydrogen, and pyrolysis oils [2, 3]. The issue will cover a wide range of feedstock and
conventional and new production methods including the challenges and prospects. In the last few decades, due to the everincreasing
exploitation of fossil fuels, there is a significant emphasis and demand on exploring and developing alternative, costeffective,
and non-food feedstocks or waste biomass sources for producing fuels and value-added products .
Micro-Algae and Macro-Algae Based Biofuels: In the last few decades, there has been tremendous research on the
utilization of micro and macro algae for biofuels production and increasing the process efficiency and quality of the products
. Despite all these efforts and investment, there remain many challenges and scope for improvement in this area before
potential commercialization of this technology worldwide. Multiple benefits are sought through these processes including biowaste
treatment, production of clean fuels and CO2 capturing for huge environmental and economic benefits. Contributions
under this subtopic would be preferred covering both the scientific and engineering aspects of algae biofuels.
Development of Advanced Catalysts for Biofuels: The role of catalysts is critical not only in the conversion process of
biofuels systems but also making the overall process more efficient, less energy intensive and economically feasible. However,
the primary challenge with the use of catalysts is huge cost. Recently, waste biomass-based catalysts such as biochar and
natural minerals like natural zeolite are utilized instead of costly commercial catalysts . Therefore, this subtopic would cover
how such cheap and effective catalysts could be developed for various biofuels systems such as transesterification (biodiesel),
anaerobic digestion (biogas), fermentation (bio-alcohols) and bio-hydrogen .
State-of-the-art Cost-Effective Bioenergy Production Technologies: This subtopic would cover the state-of-the-art and costeffective
bioenergy production technologies such as pyrolysis, supercritical water reforming, gasification, anaerobic digestion,
torrefaction, and liquid phase processing . Currently, one of the most limiting factors of bioenergy production technologies is
the high capital/ operational cost or low profitability. New ideas and paradigm will be gathered to contribute solving this issue
through this special issue. A primary emphasis would be given to such contributions which would cover the scientific aspects of
process and products chemistry.
Use of Waste and Non-profitable Natural Resources for Optimization of Biofuel Production: This subtopic would cover the
utilization of waste and non-profitable natural resources such as lands, water, and biochar, natural minerals in optimizing the
first and second generation biofuels such as bioalcohols (ethanol or methanol), biomethanation and biodiesel.
Life Cycle Assessment (LCA) of Value-Added Green Products: This subtopic would cover the aspects of both biomass waste
utilization and value-added green products in the form of fuels and energy [8,9]. The established or new models of LCA should
be used for detailed technical, economic and environmental aspects of these processes and products, crucial before moving
towards commercialization. In addition, the engineering design for feedstock processing and biofuel production plants would be
covered under this subtopic.
Integration of Waste to Energy Technologies: This subtopic would cover the various waste to energy and waste-based
biorefineries systems in an integrated way. The ultimate goal is to achieve more sustainable and environmentally friendly
systems and products. The examples of such systems include the organic waste biorefinery, agricultural and forestry residues
biorefinery . Contributors are encouraged to cover the various sources of municipal and industrial waste which could be
potentially utilized for energy, fuels, heat, and chemicals production.
As Guest Editors we would like to thank all the authors for their precious contributions and all the reviewers for their
excellent work in evaluating the submitted manuscripts. We also wish to thank the Editor in Chief, Prof. György Keglevich and
the Editorial Manager Ms. Sanober Maqbool for their kind support in preparing this Special Issue.
In the last few decades, catalyzed organic and bioorganic reactions have attracted much attention in chemical and
pharmaceutical researches [1, 2]. Recently, the design of novel catalysts and enzymes is in much demand to circumvent certain
intractable synthetic problems [3-6].
In this light, the modeling of catalytic procedures seems to be necessary and also important in the synthesis of emerging
classes of organic compounds that are becoming the targets of molecular and biomedical researches [7-10].
Strictly speaking, the combination of computational approaches with experimental methods to model and interpret the
mechanistic features of catalytic and enzymatic organic reactions provides more detailed information about the structure,
bonding, stereochemistry and spectroscopic properties of compounds through the reaction path and consequently, leads to the
new opportunities for production of novel chemicals and discovery of useful drugs [10-11].
In this context, the main goal of this thematic issue is to present comprehensive joint experimental and computational
researches set in the field of catalytic organic synthesis and their rational mechanistical underpinning and the conjunction of
experimental features of catalytic and enzymatic reactions with computational approaches will be covered.
This thematic issue contains 3 reviews, written by highly knowledgeable teams with tremendous amount of experience in
the field of computational organic chemistry, which are discussed as follows:
The first article of this special issue by Laura Orian and her coworkers from the University of Padova describes the essential
synthetic and reactivity aspects of organoselenides in a rational combination with the results of computational studies. In this
line, reactivity of the Se-Se bond and the redox properties of selenium are discussed to produce diselenides compounds for the
catalysis of many organic reactions and along with its enzymatic application as glutathione peroxidase, inspiring novel
elements for rational catalyst, enzymes and drug design.
The second review is provided by Ana María Mendoza-Wilson and her colleague on chemical structure and reactivity of
procyanidins. Clearly speaking, in this review, the recent advances of experimental and computational studies on the potential
of procyanidins as metalloproteinases inhibitors were investigated. In the last review article of this special issue by Tayebeh
Hosseinnejad and Majid M. Heravi and their co-worker, Hantzsch dihydropyridines synthesis and their biological activities and
also their applications in asymmetric transfer hydrogenation are investigated from the combined experimental and computational
As a result, the thematic issue contains the reviews of emerging and cutting edge researches in the field of computational
chemistry and modeling and hopefully attracts substantial attentions and stirs up the interest of readers in the related research
community. Finally, I would like to acknowledge all the contributing authors, reviewers and the Editorial Office for their
consistent efforts in bringing out this special issue.
Solid Phase Organic Synthesis (SPOS) was first introduced for peptide synthesis and is pioneered by R. B. Merrifield,
which later earned him a Nobel Prize in Chemistry in 1984 [1, 2]. The solid-phase synthesis carries many advantages over
classical solution-phase synthetic methods which may include purification of products by simple filtration of the polymer
matrix , automatability , easy handling, low moisture susceptibility , minimum side reaction, polymerization-free due
to site-isolation of polymer beads  and recyclability of the polymer matrix for repeated useage [7, 8]; thereby adding the
‘green’ credentials of the whole processes.
Earlier, SPOS mainly refers to a multi-step organic synthesis using a polymer-bound reagent. However, these days, the
single step organic synthesis using polymer and/ or other solid catalysts/ reagents is also included in SPOS domain.
In recent years, polymer-bound reagents/ catalysts have received major attention from industry and academia mainly due to
their easy handling, separation, and reusability [9-12]. In addition, as polymeric reagents/catalyst can be recycled and reused,
they can be used in an excess amount to drive the reaction faster.
In this special issue, different reviews related to SPOS have been contributed by experts in these fields of research:
In the paper by Prof. Ilia and co-worker entitled “Solid-Phase Synthesis of Phosphorus Derivatives”, different approached
for the solid phase synthesis of oligonucleotides, nucleobases, nucleoside, phosphates and phosphonates are extensively
Prof. Ohtaka in the paper “Transition-Metal Nanoparticles Catalyzed Carbon-Carbon Coupling Reactions in Water” reports
the most important advances in Carbon-Carbon bond formation reactions such as Suzuki coupling, Heck reaction, Sonogashira
coupling, Stille coupling, Hiyama coupling and Ullmann coupling catalyzed by different transition metal nanoparticles.
The final contribution to this special issue is provided by Rokhum et al. This review entitled “Recent Application of
Polystyrene-Supported Triphenylphosphine in Solid Phase Organic Synthesis” covers several applications of polymer-bound
triphenylphosphine as a catalyst as well as a regent in different chemical transformations such as Henry reaction, Wittig
reaction, Mitsunobu reaction, esterification reaction, and cross-coupling reaction.
As Guest Editors we would like to take this opportunity to thank all the authors who have kindly agreed to our invitation
and contributed a review for this special issue. We also wish to thank all the reviewers for their support in evaluating the
We sincerely thank the Editor-in-Chief, Prof. György Keglevich and the Editorial Manager Ms. Sanober Maqbool for their
constant support in the successful publication of this special issue. It has been a great pleasure to work with Bentham Science
In the last decades important challenges have been overcome due to the comprehension of the
supramolecular organic chemistry. Non-covalent interactions and aggregation properties often play a
central role in the development of new bioactive compounds, carriers systems and delivery devices as well
as in the improvement of natural products as starting materials for innovative uses, including tissue
engineering and medicine. In many cases different techniques are required to characterize newly formed
supramolecular systems in term of dimension, morphology, microviscosity and stability, or to point out the
aggregation tendency of the investigated molecules.
Promising strategies are also based on the formation of aggregates or the inclusion of molecules into
carrier systems for new targets; the characterization of nanoparticles; the use of the therapeutic polymers;
the synthesis of molecules mimicking natural compounds; the applications of traditional or modern
techniques to highlight aggregation properties.
The aim of this special issue is to report the recent advances in topic aspects of the supramolecular organic
chemistry in a large variety of applications involving self-assembly process and including all cases in which
the supramolecular behavior represents the relevant key for future perspectives in the scientific research.
Metal-organic frameworks (MOFs), also known as porous coordination polymers (PCPs), are
constructed from the coordination of metal ions or metal clusters with organic ligands. MOF
studies have emerged as one of the most important topics in chemistry and materials science in
the past two decades. The porosities of MOF materials can be systematically tuned by judicious
selection of molecular building blocks, and a variety of functional sites/groups can be introduced
into metal ions/clusters, organic linkers, or pore spaces through pre-designing or post-synthetic
approaches. These unique advantages enable MOFs to be used as a highly versatile and tunable
platform for various applications in gas storage and separation, chemical sensing, catalysis, and
biomedicine. MOFs have some intrinsic advantages to develop as a new class of catalytic
materials, such as their ultra-high surface areas (up to 7000 m2
/g), tunable pore sizes/shapes, and
easily immobilized catalytic active centers into metal nodes or organic linkers. Also, some
catalytically active molecules or nanoparticles could be encapsulated into the cavities of MOFs.
These attractive features have led to a rapidly growing number of MOFs for heterogeneous
catalysis. The purpose of this thematic issue is to summarize and highlight the advanced
development of MOFs and their emerging applications in organic chemistry related fields. The
topic of this issue will cover several fields that be contributed from experts from organic
chemists, inorganic chemists and materials scientists: (1) The advanced development of MOFs,
such as novel synthetic approach, post-synthesis, and In situ growth mechanism studies of
MOFs; (2) Emerging and promising applications of MOFs, such as light hydrocarbon separation,
catalytic organic transformation, photocatalysis, sensing of small molecules, bioimaging and
Inflammation results from a process in response to noxious stimuli in from tissues by pathogenic
agent and / or irritated or damaged cells from an inflammatory immune response involving the
immune cells, blood vessels and molecular inflammatory mediators .
Inflammatory diseases may be provided by an acute or chronic phase. In the acute phase we have
an innate immune response by characterized flush appearance, heat and increasing the entry into
service on site . In contrast, the chronic phase is from persistent acute inflammation by the
recruitment of monocytes, leukocytes and macrophages as well as proinflammatory cytokines.
At this stage one can achieve with tissue destruction and fibrosis necrosis site . Chronic
inflammation may lead to a number of diseases such as asthma , rheumatoid arthritis ,
atherosclerosis , intestinal diseases , among others.
The objective for this thematic issue is to report recent studies about different approaches in drug
discovery, which comprises synthesis, semi-synthesis, searches for new targets, natural products,
evaluation of biological activities, and/or theoretical approaches as structure-based approaches,
SAR, QSAR, docking and several cheminformatics methods , for investigation and selection
of new lead molecules. These efforts involve several studies to aid the drug discovery of new
options of treatment of inflammatory diseases.
I propose you a revision of the state of the art in the field nanotechnology-organic chemistry.
This a very actual, wide and open area of research that is the joint of many different research
fields. Due to this fact, there is not a book or a thematic issue that gives its state of the art. Base
on this I believe that this area needs thematic issue like this. I propose to include the study of the
organic molecules that are used in the last years for the modification of surfaces (metallic or not:
mainly silicon, organic substrates as cellulose, and carbon) and the main carriers that are used in
the delivery of actives compounds, from lipid nanoparticles to nanofibres. Moreover I propose to
include a chapter focused on the delivery of antitumoral actives.
Biopolymer means the polymers which are produced in a natural way by living species. In general their
molecular structures are composed of the units of saccharides, nucleic acids and also different additional
chemical side chains contributing to their consequences. The utilization of the biopolymers by Humans
comes under the category of food, clothing and furniture. On the other side if we talk about the industrial
applications of biopolymers, then it is found that fossil fuels are the substantial origin for the manufacture
of the commercial products for example, plastics which is presently used at very high scale. Some of the
biopolymers examples are such as Proteins, Carbohydrates, Lipids, DNA, RNA, Nucleic acids, Peptides,
Polysaccharides (glycogen, starch, cellulose etc.). There are basically four main classifications of
biopolymers available considering both natural and synthetic polymers carbohydrate based biopolymer,
starch based biopolymer, biopolymers based on synthetic materials and cellulose based biopolymers. In
this issue we are mainly focusing on the history and origination of the biopolymers, their classifications
and biopolymer based formulations such as Biocomposites etc.. We will also discuss about the various
applications of these biopolymer formulations in the field of biomedical engineering and industrial fields.
Sugar based polymers, such as polylactides, naturally degenerate in the human body without producing
any harmful side effects. Polylactides are generally used as surgical implants. Starch based biopolymers
can be used for creating conventional plastic by extruding and injection molding. Biopolymers based on
synthetic are used to manufacture substrate mats. Cellulose based biopolymers, such as cellophane, are
used as a packaging material.
In the Thematic Issue “Transformation of POPs in the environment" the selected organic
micropollutants listed by Stockholm convention as well as micropollutants listed in some other
international and national law legislations will be described. There will also be characterized
some other organic micropollutants that are not listed in current legislations but they cause
hazard for health and people life due to their estrogenic biological activity, carcinogenic,
mutagenic or teratogenic activity. The organic micropollutants include: polychlorinated
dibenzodioxyns PCDD, polychlorinated dibenzofurans PCDF, polychlorinated biphenyls PCBs,
selected insecticides and pesticides, polycyclic aromatic hydrocarbons (PAHs), halogenated
compounds (determination as AOX) and by-products of water treatment, di-2-
ethylocsylophtalans DEHP, nonylphenols NPE and ethoxylated of nonylphenols compounds
NPEO and some surfactants, such as linear alkylo benzosulphonans LAS. Moreover, the current
topic is the presence in the environment emerging organic contaminants as well as biologically
active substances so called as endocrine disrupting compounds such as: pharmaceutics and
cosmetics remains and bactericidal compounds (personal care products PCP), flame retardants
Frs and preservatives and impregnates.
Due to their essential roles in photosynthesis, chlorophylls are omnipresent from photosynthetic
prokaryotes to higher plants, being considered the most important pigments on Earth. Such vital
function derives from its structure, chlorophylls can absorb light quanta effectively, but also they
can release and take up electrons reversibly. Chlorophylls are cyclic tetrapyrroles carrying a
characteristic isocyclic five-membered ring that are functional in light-harvesting or in charge
separation in photosynthesis. The general term ‘chlorophylls’ includes several kinds of
chlorophyll structures depending of the unsaturation degrees of the macrocycle. Fully
unsaturated porphyrin macrocycle is present in c-type chlorophylls of chromophyte algae and
some prokaryotes. The chlorin system shows a saturated bond between C17-18 and it is present
for example in the chlorophylls a and b of oxygenic organism and in some bacteria. Finally, the
bacteriochlorin type exhibits two saturated bonds at C7-8 and C17-18, and it has been described
in bacteriochlorophylls of anoxygenic bacteria. During the last year, mass spectrometry has been
used successfully to obtain information of the structural configuration of the different
chlorophylls, not only related with identification and characterization but also providing insights
of the mechanism of reaction. The present theme issue will review the recent developments in
the field of mass spectrometry covering different chlorophyll structures.
It has become the scientific focus to advance the synthesis methods and the analysis techniques
for organic materials because of these materials’ importance in food, pharmaceutical and medical
industries. A good understanding of the properties of a material (e.g., composition, chirality,
structure, thermal stability and phase transformation) is crucial for food processing and safety,
drug design and manufacturing and medical applications. Thus there’s an increasing demand for
a wide range of modern characterisation techniques.
This proposed thematic issue will try to present the latest advances, trends and challenges in
modern synthesis methods and analysis techniques by collecting the review articles on some
emerging techniques (e.g., 3D printing, small angle X-ray scattering) as well as some more
traditional techniques (e.g., nuclear magnetic resonance, differential scanning calorimetry and Xray
diffraction). It will also highlight some in-situ monitoring techniques (e.g., the simultaneous
X-ray diffraction- differential scanning calorimetry technique for the characterization of solid
Chitosan, a natural polymer obtained by alkaline deacetylation of chitin, is the only cationic
polysaccharide in nature. Chitosan could be chemical modified by different ways, such as
oligomerization, alkylation, acylation, quternization, hydroxyalkylation, carboxyalkylation,
thiolation, sulfation, phosphorylation, enzymatic modifications and graft copolymerization along
with many assorted modifications. Then many derivates of chitosan could be obtained. Chitosan
and its derivates show excellent biological qualities: they are biocompatible, biodegradable,
mucoadhesive and non-toxic, and exhibit antimicrobial, antiviral gene transfection and
immunoadjuvant properties. Chitosan and its derivates have a variety of promising applications
in medicine and pharmaceutics and are presently considered as a novel carrier material in drug
delivery systems, gene therapy, tissue engineering scaffold, wound healing, antibacterial, fat
binder, hemostatic agent, hypocholesterolemic effect as indicated by the large number of studies
published over the last few years. They can be easily processed in diverse forms, such as
membranes, microparticles/nanoparticles, fibres, hydrogels or sponges, and allowing the design
of a variety of medical and pharmacological devices adaptable to end purposes. In this special
issue, I’ll bring together a number of top-ranked international scientists to discuss the recent
advances about the strategies for design, synthesis, functionalization and applications of chitosan
and its derivates for applications in medical materials. This special issue is aiming for a broad
audience of readers in the field of material sciences, chemistry, medicine and pharmaceutics.
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