Microwave Irradiation for Catalyst and Solvent Free Knoevenagel/Michael Addition/Cyclization/Aromatization Cascades
Paramita Das and Chhanda Mukhopadhyay
Affiliation: Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata-700009, India.
Keywords: Catalyst-free, green synthesis, microwave-assisted, [1, 6]naphthyridines, one-pot, pseudo-five-component, solvent-free.
A microwave-assisted reaction is developed to facilitate the construction of 1,2-dihydro[1,6]naphthyridines
from methyl ketones, amines and malononitrile. This one-pot, catalyst-free, solvent-free, pseudo-five-component synthesis
of [1,6]naphthyridines involves a sequential Knoevenagel reaction, Michael addition, ring closure and cyclizationaromatization
cascades. The advantages of this method lie in its simplicity, cost effectiveness and environmental friendliness.
High bond-forming efficiency, good yields and the use of readily available amines make this process convenient for
parallel synthesis. Moreover, the versatility of nitrile as functional group is proved since it can be readily transformed into
various other functional groups. It is believed that the time saved by implementing microwave strategy is potentially important
in traditional organic syntheses and the combination of catalyst-free, solvent-free and microwave heating will be
of importance in the search for green laboratory-scale synthesis.
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