New silicon-mediated ring expansion of n-sized conjugated cycloalkenones into homoallylic n+3 lactones

ORGN 11

Mark A. Hatcher, Kristina Borstnik, and Gary H. Posner. Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218

Silicon nucleophilic α-addition to various 2-cycloalkenones, followed ultimately by mild and rapid α-alkylation of the corresponding cycloalkanone enolates using diverse epoxides and BF3•OEt2, produces useful γ-lactols and γ-hydroxyketones. Hypervalent iodine-promoted oxidative fragmentation then yields regiospecifically unsaturated, 3-atom ring expanded, 8-10 membered homoallylic lactones with good control of alkene geometry.

New Reactions and Methodology 8:00 AM-12:00 PM, Sunday, March 28, 2004 Anaheim Convention Center -- 303A, Oral Division of Organic Chemistry The 227th ACS National Meeting, Anaheim, CA, March 28-April 1, 2004