Maltoside methyl

Maltodextrins a-amylase action on, 315 from amylose, 318,321,323 salivary a-amylase action on, 319 Maltose, /3-, mutarotation of, 23 —, l,2,2, 3,3, 4 -hexa-0-acetyl-6,6 -di-0-p-tolylsulfonyl-/3-, 241 Maltoside, methyl 6,6 -di-0-p-tolylsulfo-nyl-/3-, 241 Mannans... 

Maltose [72b]rf Methyl-0-Maltoside Methyl-0-Maltoside Sucrose [69] Sucrose [69L... 

Hehre and coworkers showed that beta amylase from sweet potatoes, an inverting, a-specific exo-(l 4)-glucanase, catalyzes the hydrolysis of jS-maltosyl fluoride with complex kinetics which indicated the participation of two substrate molecules in the release of fluoride ion. Furthermore, the reaction was strongly accelerated by the addition of methyl ) -maltoside. Hydrolysis of a-maltosyl fluoride, on the other hand, obeyed Michaelis-Menten kinetics. The main product with both a- and yj-maltosyl fluoride was )S-maltose. The results with )3-maltosyl fluoride were interpreted by the assumption of a glycosylation reaction preceding hydrolysis by which a malto-tetraoside is formed by the replacement of fluoride ion by a second substrate molecule or added methyl -maltoside (see Scheme 5). 

The degrading effect of alkali has been known for some time. Schoch, Wilson and Hudson146 concluded, from the fact that methyl /3-maltoside is stable when heated in 0.1 M caustic soda for considerable periods of time, that alkaline degradation of starch occurs only through the reducing end... 

The two primary hydroxyl groups in maltose and its derivatives show a large difference in reactivity. On selective tritylation, /3-maltose,238 benzyl /3-maltoside,239 and methyl 3-0-(methylsulfonyl)-/3-maltoside127 all gave mainly 6 -0-trityl compounds. Tritylation of cyclohexaamylose130 and amylose132,240 yielded the expected 6-0-trityl derivatives. 

On treatment with 30 equivalents of methanesulfonyl chloride in N,N-dimethylformamide for 8 days at 65°, methyl /3-maltoside gave a mixture of methyl 3,6-dichloro-4-0-(6-chloro-6-deoxy-a-D-glucopyranosyl)-3,6-dideoxy-/3-D-allopyranoside, isolated in 46%... 

Skrydstrup, Beau and co-workers122 have adapted Stork s method to the SmI2-reduction of glycosyl pyridyl sulfones bearing a silicon-tethered unsaturated group at HO-C(2). An example is shown with the synthesis of methyl a-C-zso-maltoside 172 from alkyne 170 via the 5-exo-dig radical cyclization of 171 (Scheme 56).144... 

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). 

By way of contrast, when 6.8 equivalents of BzCl was used under identical circumstances, in a manner similar to that observed with methyl (1-maltoside, a hexabenzoate with the 3 -OH free was isolated in 33% yield, and this could be chlorinated in high yield with S 2 inversion by using sulfuryl chloride and pyridine (Scheme 20). 

Richardson and Hough s efforts on the chlorination of sucrose ran in parallel with their studies on the selective chlorination of other readily available disaccharides. One notable piece of work done with Philippe L. Durette involved a study of the regioselective chlorination of methyl (S-maltoside (Scheme 31), which was undertaken with the long-term objective of possibly developing a future synthesis of the natural antitumor agent, amicetin. 

In Durette s study, he treated methyl (S-maltoside with an excess of sulfuryl chloride at low temperature in chloroform-pyridine and thereafter warmed the mixture to room temperature. After dechlorosulfation with a catalytic amount of sodium iodide in methanol and O-acetylation, the stereochemically inverted 4,6,3 6 -... 

SCHEME 31. Durette, Hough, and Richardson s study of the selective chlorination of methyl p-maltoside with sulfuryl chloride (1973). 

P. L. Durette, L. Hough, and A. C. Richardson, The chemistry of maltose. Part 1. The reaction of methyl a-maltoside with sulphuryl chloride, Carbohydr. Res., 31 (1973) 114—119. 

Aus Methyl-p-D-maltosid. W Aus Benzyl-p-D-maltosid. Aus Benzyl-3-D-cellobiosid. ... 

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