Abstract
Syntheses of 4'-acetamido-4'-deoxy-α-lactose (12) and 6'-acetamido-6'-deoxy-α-cellobiose (19) are described starting from 1, 6-anhydro-β-cellobiose (1) with seven steps. The sequence of the reaction is as follows. Selective tritylation and successive acetylation of 1 afford 1, 6-anhydro-2, 3, 2', 3', 4'-penta-O-acetyl-6'-O-trityl-β-cellobiose (2), mp 191-192°, [α]23D -11°, in 45% yield. Detritylation of 2 with hydrogen bromide in acetic acid gives two products, crystalline 1, 6-anhydro-2, 3, 2', 3', 6'-penta-O-acetyl-cellobiose (3) and sirupy 1, 6-anhydro-2, 3, 2', 3', 4'-penta-O-acetyl-β-cellobiose (4), in a yield of approximately the equal amount. Sulfonylation of 3, substitution of the sulfonate with sodium azide, reduction of the azido-group, acetolysis of the 1, 6-anhydro ring, and deacetylation afford 12. In the same manner, 19 is obtained from 4.
