Quinine-Catalyzed β-Sultam Synthesis

Significance

A catalytic protocol for the asymmetric synthesis of enantioenriched cis-β-sultams 2 is described starting from sulfonylchlorides 1 and the tosylimine derived from chloral. Quinine was found to efficiently mediate the reaction, except in the case of ethanesulfonylchloride (R = Me), where a dimeric cinchona alkaloid derivative gave the best results. One β-sultam (R = Et) was exemplarily subjected to ring-opening reactions using alcohols or primary or secondary amines as nucleophilic agents. Moreover, the methodology was extended to α-tosyliminoester. A cycloaddition-ring-opening sequence is presented giving β-aminosulfonamides 3 in one step.