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Condensation of 1, 6 : 2, 3-dianhydro-β-D-mannopyranose with 2-methyl-(3, 4, 6-tri-O-acetyl-1, 2-dideoxy-α-D-glucopyrano)-[2', 1' : 4, 5]-2-oxazoline (2) in the presence of a catalytic amount of anhydrous p-toluenesulfonic acid in boiling 1, 2-dichloroethane afforded crystalline 4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-1, 6 : 2, 3-dianhydro-β-D-mannopyranose (3) in 42% yield. Azidolysis of the oxirane ring of 3, reduction of the azido to an amino group, and N-acetylation afforded 2-acetamido-4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose (6) in 50% yield. Compound 6 was indistinguishable from the product prepared in 52.2% yield by direct condensation of 2-acetamido-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose with 2. Acetolysis of 6 provided the title disaccharide.

The title new reducing disaccharide (12) was synthesized starting from 1, 6-anhydro-β-lactose. Selective benzoylation of 1, 6-anhydro-4', 6'-O-benzylidene-β-lactose with 4 molar equivalents of benzoyl chloride in pyridine afforded the corresponding 2, 3, 3'-tri-O-benzoate (3) in 41% yield. Sulfonylation of 3 gave 2'-O-mesylate (4) or 2'-O-tosylate (6). Treatment of 4 or 6 with 1.1 molar equivalents of sodium methoxide in boiling MeOH yielded 1, 6-anhydro-4-O-(2, 3-anhydro-4, 6-O-benzylidene-β-D-talopyranosyl)-β-D-glucopyranose (7) in 50 or 66% yield. Further crop of 7 was isolated from the filtrate of 7 as the corresponding diacetate. Heating of a mixture of 7 with excess aq. KOH at 100° for 3 hr cleaved the epoxide ring of 7 trans-diaxially and, after acetylation, 2, 3-di-O-acetyl-1, 6-anhydro-4-O-(2, 3-di-O-acetyl-4, 6-O-benzylidene-β-D-idopyranosyl)-β-D-glucopyranose (9) was isolated in 84% yield. Debenzylidenation of 9 followed by acetylation, and subsequent opening of the 1, 6-anhydro-β-ring with titanium tetrachloride in CHCl3, then treatment with mercuric acetate in glacial AcOH, afforded 1, 2, 3-tri-O-acetyl-4-O-(2, 3, 4, 6-tetra-O-acetyl-β-D-idopyranosyl)-β-D-glucopyranose (11) in 43% yield. Deacetylation of 11 afforded the title compound (12) as a hygroscopic, amorphous powder which gave the crystalline tosylhydrazone.

On reaction with hypobromous acid, the unsaturated alcohol IIIa yields the diequatorial bromo epoxide XIX arising from the 5α,6α-bromonium ion XVIIIa on cleavage at C(5) by 19b-hydroxyl group with 6(O)n participation. By contrast, the bromonium ion XVIIIb generated from the unsaturated methyl ether IIIb is cleaved by water as external nucleophile to yield the unstable diaxial bromohydrin XX which undergoes cyclization to the oxirane derivative XXI. A comparison with the reaction course in homologs of the type I and II permits the conclusion that the change in regioselectivity, generally possible outcome of the 5(O)n participation, is only possible for the 6(O)n process if the participating group is a hydroxyl.