Iron-Catalyzed Cyclopropanation with Trifluoroethylamine Hydrochloride and Olefins in Aqueous Media: In Situ Generation of Trifluoromethyl Diazomethane

Let's avoid the risk! The title transformation has been developed for the synthesis of trifluoromethyl‐substituted cyclopropane derivatives (see scheme). It avoids the preparation of trifluoromethyl diazomethane and merges a number of areas: water as a reaction medium, iron catalysis, and access to reactive intermediates under operationally safe conditions.