Optimization of the selective reduction of α,β-epoxycarbonyls with silyllithium reagents

CHED 313

Sarah E. Wengryniuk and Aaron M. Hartel, hartela@winthrop.edu. Department of Chemistry, Winthrop University, Rock Hill, SC 29733

A novel selective α-reduction of α-epoxycarbonyls using silyllithium reagents has been developed.  The reaction proceeds through concomitant 1,2-Brook rearrangement and epoxide ring opening to form a silyl enol ether intermediate which is desilylated by excess silyllithium to produce synthetically useful β-hydroxycarbonyls (aldols) upon workup.  The conditions for the reaction were optimized using 2,3-epoxy-1-phenyl-1-propanone as the substrate.  Temperature, solvent and the substituents on silicon were each varied to determine the effect of each on the efficiency of the reaction.  Temperature was seen to have minimal effect; however the solvent and the number of phenyl substituents on silicon each had significant influence on the reaction yield.