Galactose 2,3,4,6-tetra-0-methyl

Jones and Peat23 separated methylated agar into an acidic and a neutral fraction by precipitation methods. From the hydrolyzate of the acidic fraction they isolated 2,4,6-trimethyl-D-galacto e, 2,3,4,6-tetra-methyl-D-galactose, and 3,6-anhydro-2,5-dimethyl-L-galactonic acid (XII, as the crystalline amide of m. p. 173°). The structure assignment of XII was made on the following basis. The rotation of its amide, [a]D —75.7°... 

As part of his monumental study20 on stachyose, Onuki converted manninotrionic acid into its completely methylated derivative, which he hydrolyzed, to obtain methylated D-galactoses and methylated D-gluconic acid. These products were isolated and identified by Onuki as 2,3,4,6-tetra-O-methyl-D-galactose, 2,3,4-tri-O-methyl-D-galactose and 2,3,5,6-tetra-O-methyl-D-gluconic acid. From these findings, Onuki proposed that manninotriose is... 

A methylation analysis of S14, performed in the authors laboratory,44 gave 2,3,4,6-tetra-O-methyl-D-galactose, 2,4,6-tri-O-methyl-D-galactose, and 2,3,6-tri-O-methyl-D-glucose in the proportions 1 1 1. Although these are the same components as previously reported, the proportions are different. In addition to these sugars, 2-deoxy-3-0-methyl-2-(methylamino)-D-glucose was also obtained. 

Methylation and hydrolysis of lactose gives a tetra-O-methyl-D-galactose and 2,3,6-tri-O-methyl-D-glucose. The same galactose derivative can be obtained from the methylation and hydrolysis of D-galactopyranose. 

Bromine oxidation of lactose followed by methylation and hydrolysis yields tetra-O-methyl-1,4-gluconolactone and the same galactose derivative as in (4). 

Total ion chromatogram penta-O-methyl-mono-O-acetylmyoinositol derived from mono-linked myoinositol, 2,3,4,6-tetra-0-methyl-l,5-di-0-acetylgalactitol derived from a terminal galactose, 2,3,6-tri-O-methyl-l, 4,5-tri-O-acetylglucitol derived from a 4-linked glu-citol, and 3,6-di-O-methyl-l, 4,5-tri-0-acetyl-2-acetamido-2-N-methylglucitol from a 4-linked S-acetylglucosamine. 

Methylation of stachyose and subsequent hydrolysis, by Onuki,20 gave 2,3,4,6-tetra-O-methyl-D-galactose (identified as the crystalline anilide), a tri-O-methyl-D-galactose and a tri-O-methyl-D-glucose (which were converted into the 2,3,4,6-tetra-O-methyl derivatives, and characterized as the crystalline anilides), and 1,3,4,6-tetra-O-methyl-D-fructose, a sirup which agreed in properties with the authentic material. 

Complete structural analysis of galactinol by the methylation method was reported66 by Kabat and associates in 1953. On hydrolysis, completely methylated galactinol gives 2,3,4,6-tetra-O-methyl-D-galactose (identified as the anilide) and 2,3,4,5,6-penta-O-methyl-D-myo-inositol (identified by oxidation to the penta-O-methylinosose, reduction, and demethylation, to give mpo-inositol and L-inositol). 

Recently, Putman and Hassid have confirmed93 the structural formula given by Colin and Gueguen. Methylation of floridoside, followed by hydrolysis, gave 2,3,4,6-tetra-O-methyl-D-galactose and 1,3-di-O-methyl-glyceritol (identified by its lack of optical rotation, and by mixed melting point of its p-nitrobenzoate with the authentic ester). Periodate-oxidation studies on floridoside also confirmed the earlier formula. 

In agreement with the earlier findings,126 approximately equimolecular proportions of 2,3,4,6-tetra-, 2,3,4-tri-, and 2,4-di-O-methyl-D-galacto-pyranose were isolated as the main products of hydrolysis of methylated e-galactan, but, in addition, small proportions of 2,3,4-tri-O-methyl-L-arabinose, 2,5-di-O-methyl-L-arabinose, and 2,4,6-tri- and 2-mono-0-methyl-D-galactose were found. Evidence in favor of partial structure XLI for the galactan framework was obtained by application to the polysac-... 

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