Iron-Catalyzed Preparation of Trifluoromethyl Substituted Vinyl- and Alkynylcyclopropanes

A convenient iron-catalyzed procedure to prepare trifluoromethylated vinyl- and alkynylcyclopropanes in a chemo- and diastereoselective manner Is presented. The active diazo compound (trifluoromethyl diazomethane) is generated in situ and used in the concomitant cyclopropanation reaction.