Aims and Objectives: The importance of acridine core structure and other heterocycles
containing its framework is well known, as they are found in numerous compounds with a variety of
biological effects. Pyridine is also an important solvent and heterocyclic nucleus for the design and
synthesis of novel molecules with biological properties. It occurs in several natural compounds
which are used as a precursor in agrochemicals and pharmaceuticals. The utility of nanostructured
metal salts because of their small size and high surface area as catalysts in organic synthesis has
drawn special attention due to their better properties such as slower reaction rate, reusability of the
catalyst, and higher yields of products compared to the bulk size. Nanosized copper iodide is one
reusable Lewis acid catalyst which has revealed several catalytic activities for the synthesis of
organic compounds and others. As part of our recent study to develop heterocyclic syntheses using
nanostructured catalysts, we now report an efficient and clean synthetic route to 4-arylacridinediones
and 6-aryldiindeno[1,2-b:2,1-e]pyridinediones via a condensation reaction catalyzed by CuI
nanoparticles under solvent-free conditions.
Materials and Methods: The present work deals with the condensation reaction of aromatic
aldehydes, ammonium acetate and active methylene compounds comprising dimedone or 1,3-
indanedione in the presence of a catalytic amount of the synthesized CuI nanoparticles could be
applied for the solvent-free preparation of 4-arylacridinediones and 6-aryldiindeno[1,2-b:2,1-
e]pyridinediones at 70 °C within 60 min.
Results: A series of 9-aryl-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H)-acridinediones
and 6-aryldiindeno[1,2-b:2,1-e]pyridine-5,7-diones were synthesized in high to excellent yields via a
simple one-pot three-component coupling reaction using the synthesized CuI nanoparticles as an
efficient and recyclable catalyst. All synthesized compounds were well characterized by their
satisfactory elemental analyses, IR, 1H and 13C NMR spectroscopy. The synthesized catalyst was
fully characterized by XRD, TEM and SEM techniques.
Conclusion: A solvent-free condensation between aromatic aldehydes, ammonium acetate and
active methylene compounds comprising dimedone or 1,3-indanedione, in the presence of CuI
nanoparticles as an efficient and recyclable catalyst leads to the formation of 4-arylacridinediones
and 6-aryldiindeno[1,2-b:2,1-e]pyridinediones. This novel and practical approach has a number of
advantages for instance, the condensation itself is solvent-free, the total amount of solvent used in
the whole process is significantly decreased, the yields of pure products are high to excellent without
any by-products, the catalyst is reusable, and the work-up is very simple.