Organocatalytic Asymmetric Sulfa‐Michael Additions to α,β‐Unsaturated Sulfonates

The reactivity of α,β‐unsaturated sulfonates and aromaticthiols in an organocatalyzed sulfa‐Michael addition was explored. Bifunctional chiral thiourea catalysts were found to promote the reaction, and the corresponding Michael adducts were afforded in moderate to good yields (24–92 %) and with moderate levels of asymmetric induction (33–64 % ee ). This study represents the first use of α,β‐unsaturated sulfonates in a catalytic asymmetric Michael addition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)