THE ASYMMETRIC CYCLOPROPANATION OF ACYCLIC ALLYLIC ALCOHOLS - EFFICIENT STEREOCONTROL WITH IODOMETHYLZINC REAGENTS

The asymmetric cyclopropanation of acyclic allylic alcohols can now be achieved with unprecedently high level of stereocontrol with halometh ylzinc reagents. The ability of proximal basic groups to ''deliver'' t he methylene unit to a nearby olefin has been used to develop efficien t reaction conditions for the cyclopropanation of allylic alcohols. Th is property was employed to improve the diastereoselection observed in the cyclopropanation of chiral, acyclic allylic alcohols; in the deve lopment of an efficient chiral auxiliary; and finally in the design of an efficient stoichiometric chiral reagent for the cyclopropanation o f allylic alcohols.