The reaction of diazoalkanes with thiophen

Abstract

During the rhodium-catalysed reaction of thiophen with diazoalkanes, three types of product are observed depending on the nature of the diazoalkane. With diazomalonic esters stable ylides are formed. Simple diazoketones such as diazoacetophenone result in 2-substitution of the thiophen ring whereas diazoacetic esters react to give 2-thiabicyclo[3.1.0]hex-3-ene derivatives. Diazoacetoacetic esters give mixed 2-substitution–cyclopropanation, with the former predominating.