Maltose methylation method

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-... 

The methods of methylation were first launched by the preparation of crystalline tetramethyl-glucose (7). Galactose (8), sucrose, and maltose (9) were subjected to methylation, and in 1906 the method was extended to determine die stmcture of the natural glucoside, salicin (10). Denham and Woodhouse (11) in 1910 were able to introduce methyl groups into cellulose. A modification of die mediylation method enabled it to be apphed to the preparation of glucosides and mediylated glucosides (12) and the simplification of work in such cases facilitated the eonstitutional study of sucrose, lactose, maltose, and cellobiose (13, 14, 15). 

The complexings of D-glucose, D-fructose, and maltose with borate anions have been studied by polarimetric, conductivity, and pH measurements, and circular dichroism methods have been used to investigate the complexing of cuprammonium ions with carbohydrate diols and amino-alcohols. An examination of the c.d. spectra of fifteen methyl 3-acetamido-3,6-dideoxyhexopyranoside derivatives measured in methanol, 2,2,2-trifluoroethanol, and acetonitrile su ests that the amide group is not completely planar and may show chirality. The n it transition of the carboxylic acid carbonyl groups at... 

Potentially valuable selective acylations of disaccharides are mentioned in Chapter 6 and, from methyl jS-cellobioside 2,6,2, 3, 4, 6 -hexa-acetate, methyl 4-0-j8-D-glucopyranosyl-j8-D-allopyranoside was produced. Likewise, methyl 4-0-a-D-galactopyranosyl-j8-D-allopyranoside and 4-O-a-D-glucopyranosyl-D-allose were prepared from methyl /3-D-maltoside 2,6,2, 3, 6 -pentabenzoate and -maltose l,3,6,2, 4, 6 -hepta-acetate, respectively. Related methods led to fl/ac/o-sucrose. ... 

A number of papers have appeared aimed at elucidating the conformational aspects of the inter-glycosidic linkages of di- and trisaccharides by n.m.r. methods. Stereospecific H-labelling at C-6 allowed the identification of the signals due to H-6(R) and H 6( ) in the n.m.r. spectra of methyl /S-maltose and methyl p-isomaltose, and determination of the and values... 

Reactions carried out on disaccharide derivatives included the conversion of peracetates to l-phenylthio- 3-derivatives by use of phase-transfer methods and the epimerization at C-2 by calcium -amine systems (CaCl2.2H20, EtjN, for example). By this means maltose, lactose, isomaltose and melibiose were converted into the corresponding glucosyl-D-mannoses. An extensive range of variously substituted maltosyl fluorides have been made from maltose derivatives as substrates for cyclodextrin transferase. Only the 6 -methyl ether and 6 -acetate were transformed into cyclic products. In the course of the work the thio-derivatives (83) and (84) were made. ... 

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