Cyclic Vinyl p-Tolyl Sulfilimines as Chiral Dienophiles:  Diels−Alder Reactions with Furan and Acyclic Dienes

The dienophilic behavior of the sulfilimine 2, synthesized from (Z)-3-p-tolylsulfinylacrylonitrile 1, in its Diels−Alder reactions with furan and acyclic dienes has been investigated. A complete π-facial selectivity for 2, opposite to that observed from its precursor 1, is the main feature of all these cycloadditions. Moreover, the high exo selectivity observed in reactions of 2 with furan (not observed for 1) contrasts with the almost complete endo selectivity with other cyclic and acyclic dienes. Additionally, the opposite regioselectivities obtained for 2 with Dane's diene and 1-substituted butadienes (not observed for 1) are also noteworthy. This behavior allows dienophiles 1 and 2 to be considered as complementary precursors from a synthetic point of view.