N-Vinyl-1,3-oxazolidine-2-thiones as Dienophiles in Inverse Hetero-Diels-Alder Reactions: New Prospects for Asymmetric Induction

Several N-vinyl-1,3-oxazolidine-2-thione (N-vinyl OZT) were conveniently used as new dienophiles in Eu(fod)3-catalyzed reverse hetero-Diels-Alder reactions involving benzylidene pyruvic acid methyl ester. Simple chiral N-vinyl OZT analogues homogeneously led to moderate endo and facial diastereoselectivities, when compared to those obtained with the corresponding N-vinyl-1,3-oxazolidin-2-ones. In contrast, high diastereocontrols were ­observed with a sugar-derived N-vinyl OZT.