title: Enantioselective Cyclopropanation of Allylic Alcohols. The Effect of Zinc Iodide.
abstract: The effect of zinc iodide on the catalytic, enantioselective cyclopropanation of allylic alcohols is examined with bis(iodomethyl)zinc as the reagent and bis-methanesulfonamide 7 as the catalyst. Significant rate enhancement was observed when 1 equiv of zinc iodide was present, but more importantly, the enantiomeric excess of the product cyclopropane increased from 80% to 89% for the substrate cinnamyl alcohol. Reaction studies and spectroscopic investigations show that this remarkable influence is the result of reagent modification via a Schlenk equilibrium that produces the more reactive and selective species (iodomethyl)zinc iodide.
authors.affiliation: Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801.
authors.forename: Scott E.
authors.initials: SE
authors.lastname: Denmark
authors.forename: Stephen P.
authors.initials: SP
authors.lastname: O'Connor