Reinvestigation of the chemoselective cyclopropanation of allylic alcohols, allylic ethers and alkenes: a comparison between various reagents and protocols

The relative reactivities of various Zn, Al and Sm carbenoids in the chemoselective Simmons–Smith cyclopropanation of geraniol and its benzyl ether derivative were studied. Directed cyclopropanation was obtained in all cases, even with a iodomethylaluminum reagent. By variation of the reaction protocols using aluminum carbenoids, cyclopropanation can favor the proximal or distal double bond.