DMAP-Catalysed Sulfinylation of Diacetone-D-Glucose: Improved Method for the Synthesis of Enantiopure tert-Butyl Sulfoxides and tert-Butanesulfinamide

An improved method for the tert-butanesulfinylation of diacetone glucose with tert-butanesulfinyl chloride is reported. The method is based on a beneficial effect of catalytic DMAP, which enhances both the rate of the reaction and the enantioselectivity of the process to give (R-S)-diastereomer 2R(S) with a 94% de and in quantitative yield. (R-S)-DAG sulfinate ester 2R(S) is an excellent intermediate for the synthesis of enantiopure tert-butyl sulfoxides. Grignard agents and organo-lithium reagents can displace smoothly the diacetone glucose moiety to give synthetically relevant enantiopure sulfoxides, including highly functionalized derivatives, in high yields and with high enantioselectivities. (R-S)-DAG sulfinate ester 2R(S) is also an excellent N-sulfinylating agent; simple addition of LiHMDS (lithium hexamethyldisilazide) in THF gives (SS)-tert-butanesulfinamide, and N-tert-butanesulfinylimines are then formed in a two-step one-pot manner. N-Alkylated tert-butanesulfinamides are formed by the condensation of 2R(S) with lithium amides.