Asymmetric Mukaiyama−Michael Addition of Acyclic Enones Catalyzed by <i>a</i><i>llo</i>-Threonine-Derived <i>B</i>-Aryloxazaborolidinones

Abstract

[reaction: see text] O-(2-Naphthoyl)-N-tosyl-L-allo-threonine-derived B-phenyloxazaborolidinone catalyzes the asymmetric Mukaiyama-Michael addition of simple acyclic enones to give adducts of 54-85% ee. 2,6-Diisopropylphenol as an additive is demonstrated to effectively retard the undesirable Si(+)-catalyzed racemic pathway.