Remarkable Diastereoselectivity of the Thia-Michael Reaction on α,α′-Di[(E)-benzylidene]alkanones: Exclusive Formation of a meso Product

Abstract

Thia-Michael addition of thiophenol to α,α′-di[(E)-benzyl­idene]alkanones of both cyclic (six-membered) and acyclic varieties using anhydrous K2CO3 or amberlyst-15 as catalyst has been found to be highly diastereoselective at 15 °C. A one-pot protocol was developed for such reactions by a tandem aldol-thia-Michael process. The stereochemistry of the products was confirmed by X-ray crystallographic studies and in all cases formation of a meso product was observed.