An isoxazole strategy for the synthesis of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates – versatile building blocks for assembling pyrrolo-fused heterocycles

Abstract

A full atom-economical domino method has been developed for the preparation of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates by transannulation of 5-alkoxyisoxazoles with malononitrile under Fe(II) catalysis. Alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates are excellent building blocks for various annulation reactions, leading to new derivatives of 1H-pyrrolo[1,2-a]imidazole and pyrrolo[2,3-d]pyrimidine. The DFT calculations of mechanistic details of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylate formation are presented.