The synthesis of several α-oxo sulfines is discribed. Various α-oxo sulfines can be isolated as such. The Diels-Alder reaction of these sulfines with 1,3-dienes can be catalyzed by Lewis acids.
Selected racemic trans-2-alkoxycarbonyl-3,6-dihydro-2H-thiopyran S-oxides 2a–h have been subjected to enzyme-assisted hydrolysis under conditions of kineticresolution to give the corresponding acids and recovered esters with moderate to high enantiomeric purities (up to 95%). The enantioselectivity of the reaction was found to be strongly dependent on the structures of the substrates used.