Cyclopropanation of Terminal Alkenes through Sequential Atom-Transfer Radical Addition/1,3-Elimination.

An operationally simple method to affect an atom-transfer radical addition of commercially available ICH2 Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in a one-pot process into the corresponding cyclopropane upon treatment with a fluoride source. This method is highly selective for the cyclopropanation of unactivated terminal alkenes over non-terminal alkenes and electron-deficient alkenes. Due to the mildness of the procedure, a wide range of functional groups such as esters, amides, alcohols, ketones, and vinylic cyclopropanes are well tolerated.