Study On Synthesis Of Polysubstituted Pyrroles From Activated Alkynes And N-propargylamines Via Base-catalyzed Cascade Reaction

Pyrroles,an important class of heterocycles,were found in tremendous range of natural products and biologically active compounds.Furthermore,pyrrole-based derivatives serve as useful intermediates in preparation of pesticides,drugs,dyes,flavor components,and functionalized materials.Many methods have been developed for the pyrrole synthesis over the years.However,some of these synthetic protocols either needed expensive metal catalysts,or made use of reagents which generate halide or other molecular wastes.This article reported a novel base-catalyzed synthesis of different polysubstituted pyrroles by activated alkynes and N-propargylamines.The research results are summerized as follows:1.A novel method for K₃PO₄-catalyzed synthesis of different polysubstituted pyrroles has been developed.K₃PO₄-catalyzed cascade Michael addition/alkyne carbocyclization of activated alkynes and N-propargylamines to afforded a range of polysubstituted（tri-,tetra-,and penta-substituted）pyrroles.This transition-metal-free cascade process represented an environmental friendly and efficient way to construct polysubstituted pyrroles in good yields.2.A novel method for CsF-catalyzed synthesis of different polysubstituted pyrroles has been developed.When changing the base to CsF,the cascade reactions of activated alkynes and N-propargylamines afforeded different substituted-pattern of pyrroles via a Michael addition/aza-Claisen rearrangement/carbocyclization process.Compared with published methods,our procedure has advantages of efficient,easy operation,step-economy and atom-economy.