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. (C) 2001 Elsevier Science B.V. All rights reserved.