Synthesis and dienophilic behavior of (S)-2-cyano-3-(p-tolylsulfinyl)-1,4- benzoquinone

Hydrocyanation of 2-(p-tolylsulfinyl)-1,4-benzoquinone (2) followed by oxidation with PhI(OAc)(2) gives 2-cyano-3-(p-tolylsulfinyl)-1,4-benzoquinone (1). The generation of 1 in the presence of cyclic and acyclic dienes affords the Diels-Alder adducts with a complete chemo- (only reaction with the sulfinyl-substituted double bond takes place), regio- (controlled by the cyano group), and endo selectivity (with respect to the quinone moiety), whereas the pi-facial selectivity is dependent on the structure of the diene.