C2-Symmetric Bis-Sulfoxide: Highly Diastereoselective 1,4-Addition to Stabilised Michael Acceptors

The reaction of (S,S)-bis-p-tolylsulfinylmethane with highly stabilised Michael acceptors was studied in detail. The stereochemical outcome of the reaction was shown to be under thermodynamic control. While an equimolar mixture of Michael adducts was obtained at −78°C, warming the reaction to room temperature allows the formation of a single isomer in quantitative yield.