Intermolecular Metal‐Free Cyclopropanation of Alkenes Using Tosylhydrazones

Abstract

Abstract We describe the first general method for the metal‐free cyclopropanation of alkenes by using N ‐tosylhydrazones as an in situ source of diazo compounds. This new method works with a wide variety of alkenes (styrene derivatives, dienes, enynes, and electron‐deficient alkenes) by using N ‐tosylhydrazones derived from various ketones or aldehydes (aromatic, aliphatic, enones). The reaction is performed with the use of K 2 CO 3 as a base to form the diazo species and is compatible with a wide array of functional groups.