1,4-Bis(arylsulfonyl)dihydropyridines in synthesis. Enantioselective synthesis of 2,3,6-trisubstituted piperidines

A 2-substituted 1,4-bis(4-tolylsulfonyl)-1,2-dihydropyridine is readily accessed from an α-aminoester and 1,1-dimethoxy-3-(4-tolylsulfonyl)propane. This cyclic diene enters into highly selective addition reactions with carbon nucleophiles, and the product of one of these transformations is converted into a 2,3,6-trisubstituted piperidine via an SN1′ reaction.