The synthesis of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside hydrochloride

The N-trifluoroacetyl- and N-tetrachlorophthaloyl-protected bromide of d-glucosamine has been used for the first time as a glycosyl donor for the glycosylation of diosgenin [(25R)-spirost-5-en-3β-ol]. Both 1,3,4,6-tetra-O-acetyl-2-deoxy-2-trifluoroacetamido-β-d-glucopyranoside and 1,3,4,6-tetra-O-acetyl-2-deoxy-2-tetrachlorophthalimido-α,β-d-glucopyranoside were transformed into the appropriate glycosyl bromides. These reacted with diosgenin under mild conditions, using silver triflate as a promoter, and gave the corresponding protected diosgenyl glycosides. Each was deprotected to give diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside hydrochloride. The structures of the new glycosides were established by 1H NMR spectroscopy.