title: Novel isomerically pure tetrasubstituted allylboronates: stereocontrolled synthesis of alpha-exomethylene gamma-lactones as aldol-like adducts with a stereogenic quaternary carbon center.
abstract: In spite of their inherent isomerization tendency and low reactivity, 1-alkoxycarbonyl vinylcopper(I) intermediates from the conjugate addition of organocuprates onto acetylenic esters were trapped with very high cis-addition selectivity with iodomethylboronic esters in the presence of HMPA. The resulting isomerically pure 3,3-disubstituted allylboronates react with aldehydes in a highly diastereo- and enantioselective manner, providing alpha-exomethylene gamma-lactones with a stereogenic quaternary beta-carbon center.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
authors.forename: Jason W J
authors.initials: JW
authors.lastname: Kennedy
authors.forename: Dennis G
authors.initials: DG
authors.lastname: Hall