Timothy A. Boebel and David Y. Gin
A versatile glycosylation reaction is used to establish the process of sulfoxide covalent catalysis. Hemiacetals are activated by benzenesulfonic anhydride and a dialkyl sulfoxide catalyst, nBu2SO, for coupling with various nucleophiles (Nu; see scheme, TTBP=2,4,6-tri-tert-butylpyridine). The sulfoxide catalyst functions uniquely in three capacities, first as an O nucleophile, then as a S+ electrophile, and finally as a leaving group to fulfill turnover.