Pyridine- <i>N</i> -oxide catalyzed asymmetric <i>N</i> -acylative desymmetrization of sulfonimidamides

A highly efficient enantioselective <i>N</i>-acylative desymmetrization of sulfonimidamides with chloroformates was reported using chiral 4-arylpyridine-<i>N</i>-oxide as the catalyst, affording <i>N</i>-acylative sulfonimidamides with sulfur(vi)-stereocenters in high yields and excellent enantioselectivities. Experiments and DFT calculations support an acyl transfer mechanism, and the nucleophilic substitution of sulfonimidamide by the <i>O</i>-acyloxypyridinium cation intermediate is the enantio-determining step of the reaction. The reaction features variability for acyloxy groups and compatibility with moisture.