CuI/Cu(OSO2CF3)2 catalysed convenient approach to dichromenopyridines and triazole-thiazole appended chromone derivatives

Abstract

A variety of new pentacyclic dichromenopyridines have been synthesized from 2-amino chromone and O-propargyloxy salicilaldehydes through intramolecular Povarov reaction using CuI/Cu(OSO2CF3)2 as a Lewis acid catalyst. The dichromenopyridines synthesis involve two sequential steps, insitu N-heteryl aldimine formation and an intramolecular Aza Diels-Alder[4 + 2] cycloaddition. Furthermore the key intermediate, terminal alkyne tethered Schiff bases subjected to Cu(I) mediated click [3 + 2] cycloaddition with thiazole appended azide to afford imine linked chromone-1,2,3-triazole -thiazole tri heterocyclic molecular hybrids.