Catalytic Conjugate Addition of Acyl Anion Equivalents Promoted by Fluorodesilylation

The conjugate addition of acyl anion equivalents derived from 2-silyl-1,3-dithianes to alpha,beta-unsaturated ketones and esters has been achieved using a substoichiometric amount of TBAF. High yields and short reaction times are observed for the addition of aryl-1,3-dithianes to a variety of cyclic and acyclic alpha,beta-unsaturated carbonyl acceptors. Observation of the reactive anion by C-13 NMR spectroscopy and extension to an-asymmetric variant is also presented.