Unusual Rearrangement of Dihalocyclopropanes

Abstract

Dihalocyclopropanation of the double bond of some olefins, leading to dihalocyclopropanes, offered an opportunity to perform their rearrangement to dihalomethylvinyl with Hiyama type reagents, in presence of cationic system such as Cr²⁺/Cr³⁺. The chain elongation of alkenes via the gem‒dihalocyclopropanes produced α,β–unsaturated aldehydes and acids.