Rhodium-Catalyzed Cyclopropanation of Alkenes with Dimethyl Diazomalonate

The outstanding ability of dirhodium a,a,a',a'-tetramethyl-1,3-benzenedipropanoate [Rh 2 (esp) 2 ; esp = α,α,α',α'-tetramethyl-1,3-benzene-dipropanoate] to catalyze the cyclopropanation of a wide range of alkenes with malonate-derived carbenoids under mild reaction conditions is reported in this communication. The experimental protocol is remarkably simple, uses readily accessible and stable dimethyl diazomalonate with very low catalyst loading. More importantly, the alkene is employed as a limiting reagent.