Synthesis of 1D-(1,3,5/2,4)-4-acetamido-5-amino-1,2,3-cyclohexanetriol and its incorporation into a pseudo-disaccharide.

The synthesis of the title compound and 1D-(1,3,5/2,4)-4-acetamido-5-amino-3-O-(beta-D-glucopyranosyluronic acid)- 1,2,3-cyclohexanetriol [sequence: see text] is described. Starting from methyl 2-acetamido-2-deoxy-alpha-D-glucopyranoside 2L-(2,4,5/3)-4-acetamido-3-benzoyloxy-2-benzyloxy-5- hydroxycyclohexanone [sequence: see text] was prepared via a series of transformations including the regioselective ring opening of the benzylidene acetal and the mercury(II)-catalyzed carbocyclic ring closure reaction of 5-enopyranoside. Stereoselective reduction of ketone 11 with NaBH(OAc)3 gave 1D-(1,2,4/3,5)-2-acetamido-3-O-benzoyl-4-O-benzyl-1,3,4,5- cyclohexanetetrol [sequence: see text] (88%), which was then converted into 1D-(1,3,5/2,4)-4-acetamido-5-azido-3-O-benzoyl-2-O- benzyl-1-O-pivaloyl-1,2,3-cyclohexanetriol [sequence: see text] through selective 5-OH protection, 1-O-mesylation, and subsequent azide displacement. Saponification and hydrogenation of this gave the title compound. Selective O-debenzoylation with 1.1 equiv of K2CO3 in MeOH gave 1D-(1,3,5/2,4)-4-acetamido-5-azido-2-O-benzyl-1-O- pivaloyl-1,2,3-cyclohexanetriol [sequence: see text] (73%). Glycosylation of this compound with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide) uronate in Ch2Cl2, using silver triflate as the promoter, afforded 1D-(1,3,5/2,4)-4-acetamido-5-azido-2-O-benzyl-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-1-O- pivaloyl-1,2,3-cyclohexanetriol [sequence: see text] and subsequent hydrogenation of this compound gave the basic pseudo-disaccharide.