Zinc(ii)-catalysed cyclocondensation of oxime ethers triggered by polarity inversion: construction of fused pyrroles

Abstract

An efficient approach for the synthesis of fused pyrroles such as indoles, thieno[3,2-b]pyrroles, and benzothieno[3,2-b]pyrroles possessing an N-alkoxy group was developed via the Zn(II)-catalysed cyclocondensation of α-hydroxy oxime ethers. Important features include the scalable synthesis with high yield achieved (up to 99%), environmentally benign, low-cost catalysts, and less hazardous reaction conditions.