Enantioselective [4 + 2] cycloaddition of cyclic N-sulfimines and acyclic enones or ynones: a concise route to sulfamidate-fused 2,6-disubstituted piperidin-4-ones.

A concise route to valuable sulfamate-fused 2,6-disubstituted piperidin-4-ones or 2,3-dihydropyridin-4(1H)-ones in good yield with high diastereo- and enantioselectivity is presented. The combination of chiral primary amine and o-fluorobenzoic acid efficiently promoted an asymmetric [4 + 2] cycloaddition reaction of N-sulfonylimines and enones or ynones. The cycloaddition reaction between cyclic N-sulfonylimines and ynones is first reported.