The synthesis of a diastereoisomer of methyl acarviosin

In model studies, a fully protected D-galactopyranoside 4-triflate and two 6-deoxy analogues were shown to alkylate cyclohexylamine, leading to 4-cyclohexylamino-4-deoxy- and 4,6-dideoxy-D-glucopyranosides as the major products in satisfactory yield, accompanied by alkenes resulting from elimination of triflic acid. Coupling of tetra-O-benzyl-l-epivalienamine with methyl 3- O-benzoyl-6-deoxy-4-O-trifluoromethylsulfonyl-β-D-galactoside gave a diastereoisomer of methyl acarviosin in protected form. Deprotection completed the first synthesis of methyl 4,6-dideoxy-4-[(l′R,4′R,5′ S,6′S)-4′,5′,6′-trihydroxy3′-(hydroxymethyl) cyclohex-2′-enyl]amino-β-D-glucoside, a potential β-glycosidase inhibitor.