Many medium ring-sized heterocyclic motifs are found in naturally occurring compounds
of significant biological activity which led to the investigation of the biological activity of simpler
heterocyclic compounds accommodating these ring systems. Therefore, the development of newer
synthetic methodologies to access such ring systems has remained an important activity over the last
few decades. However, common methods of their synthesis are usually associated with thermodynamic
disadvantages. Many metal-mediated transformations e.g., Heck reaction, Suzuki reaction, etc.
tend to overcome some of these effects but at the cost of environmental disadvantages. In recent
years, several green chemical techniques have found useful applications in the synthesis of such ring
systems. In particular, the use of microwave technology has provided better opportunities. The present
review attempts to highlight many synthetic approaches developed for the synthesis of such heterocyclic
scaffolds of pharmacological interest involving condensation reaction, coupling reaction,
Multi-component reaction, Cyclo-addition reaction, Dipolar cycloaddition reaction, etc. An emphasis
has also been given on the distinct advantages offered by microwave application over classical approaches,
wherever such knowledge is available.
Keywords: Microwave, oxepine, azepine, diazepine, oxazepine, thiazepine, bioactive molecules, condensation reaction, multicomponent
reaction, metal-catalyzed reaction.
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