ASSESSMENT OF THE ABSOLUTE-CONFIGURATION OF A SERIES OF AROMATIC ENDOCYCLIC SULFOXIMIDES

Racemic 1-methyl-3-oxo-benzo [n] isothia(IV)azole 1-oxide (1a), obtain ed via electrophilic amination of 2-(methylsulfinyl)benzoic acid (2a), was resolved into its enantiomers by semipreparative chiral liquid ch romatography. The (+)-form of 1a was recrystallized to give single cry stals suitable for direct determination of the absolute configuration by X-ray crystallography. The subsequent X-ray data analysis gave the (S)-absolute configuration. (+)-(S)-1a gives, like the 1-octyl analogu e (1b), a positive CE in its CD-spectrum. These results were used to c orrelate the configurations of the parent sulfoxide and the resulting sulfoximide. This showed that while the reaction using MSH (O-mesityle nesulfonyl-hydroxylamine) gives a product with retained configuration at sulfur, the reaction using hydrazoic acid proceeds with inversion a nd partial racemization.