Maltoside methyl, heptaacetate

SCHEME 9. Durette, Hough, and Richardson s synthesis of methyl 3-bromo-3-deoxy-p-maltoside via opening of the 2,3-allo-epoxide derived from the l,2,2, 3, 4, 6,6 -heptaacetate of methyl p-maltopyranoside (1974). 

Comparison of the -n.m.r. spectrum of 3-0-(methylsulfonyl)-/3-maltose heptaacetate (31) with that of /3-maltose octaacetate showed only one divergence, —0.34 p.p.m. upfield of the H-3 resonance, indicative of the location of the methylsulfonyloxy group on C-3. A similar comparison of H-n.m.r.-spectral parameters as between methyl 4 -0-(methylsulfonyl)-/3-maltoside hexaacetate and methyl /3-maltoside heptaacetate revealed that the methylsulfonyloxy group in the former compound is located on C-4, as the H-4 resonance appeared —0.3 p.p.m. to higher field than the H-4 resonance for the heptaacetate.66 In the H-n.m.r. spectrum of methyl 3-azido-3-deoxy-/3-maltoside heptaacetate, the H-3 resonance appeared at 1.70 p.p.m. to higher field of... 

When the true structure of these ortho ster derivatives was finally recognized, Freudenberg and Scholz reported that the new crystalline methyl maltoside heptaacetate contained one acetyl group bound differently from the other six on distillation of the substance with potassium stearate in alcoholic solution only six acetyl groups were removed in the form of ethyl acetate, which was determined quantitatively in the distillate. The presence of the seventh acetyl group was revealed by the... 

Pacsu and Rich" discovered a new method, by which it was possible to obtain the new methyl maltoside heptaacetate in one step and in fairly good yield. The procedure consisted in the treatment of 9-maltose octaacetate in chloroform solution with aluminum chloride at room temperature. Freudenberg and I vers chloro-com pound was not isolated but the reaction mixture was treated with methyl alcohol in the presence of pyridine hexaacetylmaltose methyl 1,2-orthoacetate with m. p. 164 and -1-98.8 was obtained in 30% yield. Pacsu and Rich at-... 

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