One-pot preparation of isomeric acetyl- and 2,2,2-trifluoroacetyl-azidothiophenes by selective bifunctionalization of dibromothiophenes via halogen–lithio exchange

Abstract

A series of isomeric acetyl-(1) and 2,2,2-trifluoroacetyl-azidothiophenes (2) are prepared from 2,3-, 3,4- and 2,5-dibromothiophenes via a one-pot procedure entailing stepwise halogen–lithium exchange and successive reaction of the resulting thienyllithium derivatives with N,N-dimethylacetamide (or N,N-diethyl-2,2,2-trifluoroacetamide) and tosyl azide.