RECENT ADVANCES IN THE SYNTHESIS OF SPECIALIZED HETEROCYCLIC MOLECULES BY 1, 3-DIPOLAR CYCLOADDITION REACTION: A STUDY BASED ON GREENER PROTOCOLS

In today’s scenario trying newer methods or concepts in organic synthesis leading to the generation of new heterocycles and also saving the environment is equally challenging indeed for an organic chemist. Keeping in mind we feel that “green chemistry” methodologies are the need of the hour to save our environment and mankind. The aim of this review is to provide an overview of green chemistry protocols for the synthesis of a new class of specialized heterocyclic molecules via 1,3-dipolar cycloaddition reaction. In the present review, particular attention has been focused on the application of mechanochemical procedures and the use of green solvents. In addition, the review also includes reactions performed in ionic liquids, microwave-induced reactions, aqueous phase synthesis and light-induced reactions reported recently. This account also reports about the recent green synthetic methodologies of new nitrones and their cycloaddition reactions performed in our and other laboratories. We have also explored several protocols of atom efficient reactions of nitrones and further application of cycloadducts using green chemistry methodologies. The advantages of these procedures over existing conventional methodologies and the effect of solvents have been focused in this review to highlight different aspects of environmental issues and also in the selectivity of the reactions.