A novel allylic substitution strategy to four-component synthesis of pyrazole-substituted fused pyrroles
摘要:
The selective formation of pyrazole-substituted fused pyrroles through HOAc-mediated multicomponent reactions of enaminones with arylglyoxal monohydrates and generated in situ pyrazole-3-carboxylates was developed. It constructed a variety of bis-heterocyclic pairs under mild conditions in a domino process. Reaction driving tandem cyclization/allylic esterification/allylic substitution was achieved through the formation of in situ generation of allyl esters and pyrazole-3-carboxylates from readily available starting materials. Up to two new five-membered heterocyclic rings and five new sigma bonds including a C(sp3)-C(sp2) bond were formed in a single reaction without isolated intermediates. (C) 2013 Elsevier Ltd. All rights reserved.