Maltose octaacetate

Synthetic transformation of 6-maltose octaacetate (10) into the glycosyl acceptor 8 and glycosyl donor 9 is shown in Scheme 2. 

Ethyl l-thio-/3-maltoside heptaaeetate (59) has proved to be a useful intermediate in the synthesis of the a-glycoside of maltose (see Section III).30 Treatment of /3-maltose octaacetate with ethanethiol and fused zinc chloride gave compound 59 in 83% yield. Synthesis of mal-... 

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... 

The improvement in the yields of bis(amido) sugars, previously observed6 when water was used instead of methanol, was re-investi-gated in the ammonolysis of maltose octaacetate.47 As already mentioned, the yield of l,l-bis(acetamido)-l-deoxymaltitol (49, see p. 93) changed from 0.8 % in methanol to 27 % in water. Analogous results were obtained (see p. 94) for octa-O-acetylmelibiose.49 The interpretation of these differences was based on previous studies63 on the ammonolysis of simple esters. 

Maltose, heptaacetate, I, 81 a-Maltose, octaacetate, III, 377 -Maltose, octaacetate, III, 377 Maltose, phenylosazone, reaction with KOH, III, 40... 

Fig. 13.—Chromatograms, on Hydrated Magnesium Acid Silicate, of (a) a- and (3-n-Glucopyranose Pentaacetates and of (b) -Gentiobiose Octaacetate and/S-Maltose Octaacetate.

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-... 

Elevated temperatures are apparently required to cause acetylation of untreated starches by acetic anhydride. Wheat starch, for example, is not acetylated by this reagent at 35°. At temperatures sufficiently high to produce acetylation, however, acetic anhydride causes extensive degradation of the starch molecules, resulting at 95° in the production of considerable quantities of maltose octaacetate. ... 

A thorough x-ray investigation of p-maltose octaacetate" lends support to our calculations. The crystal conformation is close to our middle conformer in the minimum valley, see Table 5-1 The C5-C6 conformation is g g in the reducing sugar and alternateley ga and ag in the nonreducing, confirming our calculated possibilities. For... 

A remarkable inertness towards acylation is shown by the secondary hydroxyl group on C-3 in maltose, lactose, and their methyl j8-glycosides. Benzoylation of maltose with 10 molar equivalents of the acid chloride in pyridine gave122 the octabenzoate and the l,2,6,2, 3, 4, 6 -hepta-0-benzoyl derivative in the ratio of 5 6, and treatment of /3-maltose monohydrate with 8.8 molar equivalents of acetyl chloride in pyridine-toluene at 0° gave123 the 1,2,6,2, 3, 4, 6 -heptaacetate and the octaacetate in the ratio of 27 10. Under similar conditions of benzoylation, cellobiose was converted into its oc-... 

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