Stereoselectivity in the condensation reactions of 1-phenylethyl alkyl and phenyl ketones with organometallic reagents

Abstract

Stereochemical results of the condensation reactions of a series of ketones, PhCHMeCOR (R = Me, Et, Prⁱ, Bu^t, Ph), with various organomagnesium and organolithium derivatives in ethers as solvents are reported. Results are accounted for on the basis of competition between two transition states which may adopt either Karabatsos- or Felkin-type conformations according to the nature of R, the reagent nucleophilicity, and the polarity of solvent. Polar and steric analysis of this reaction allows highly stereoselective syntheses of diastereoisomeric α-phenylalkanols to be devised.