Benzylation of Carbohydrate Derivatives in Dimethyl Sulfoxide.

Iwashige, Tadahiro; Saeki, Hiromichi

doi:10.1248/cpb.15.1803

Cited by 62 publications

(17 citation statements)

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“…The mixture was stirred for 30 min, after which benzyl chloride (3 ml) was added dropwise and stirring was continued for another 2.5 h. The reaction mixture was then poured into ice water (50 ml) which was extracted three times with chloroform. The dried (MgS04) extract was evaporated at 2 mm Hg, leaving an oil which was passed through a small column of silica gel The same procedure applied to methyl B-D-galactofuranoside furnished the p-anomer of 16, [a], -49" (c 2, CHCI,), as reported (26). Its OCH, signal occurred at 6 3.33, and its pattern of ring proton signals was distinctively different from that of 16.…”

Section: Preparatiotl Of Fully Benzylated Metlgvl D-galactosidesmentioning

confidence: 91%

“…It yielded methyl a-D-galactopyranoside (fractions 1 6 2 0 , 1. Methyl a-and 13-D-galactopyranoside, respectively, were benzylated with benzyl chloride and potassium hydroxide as described (19), or by use of the method (26) detailed in the next paragraph. The O C H , signal of the benzylated a-pyranoside was at 6 3.35, and that of the P-pyranoside at 6 3.51 (in CDCI,).…”

Section: Preparatiotl Of Fully Benzylated Metlgvl D-galactosidesmentioning

confidence: 99%

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Concerning the Problem of Stereospecific Glycosylation. Synthesis and Methanolysis of some 2-O-Benzylated D-Galactopyranosyl and D-Galactofuranosyl Halides

Fréchet¹,

Baer²

1975

Can. J. Chem.

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. Can. J. Chem. 53,670(1975). Acetolysis of 1,6-anhydro-2,3,4-tri-O-benzyl-~-~-galactopyranose (3) followed by de-0-acetylation and p-nitrobenzoylation gave 2,3,4-tri-O-benzy1-1,6-di-O-p-nitrobenzoyl-~-~-galactopyranose (4) which was converted into 2,3,4-tri-0-benzyl-6-0-p-nitrobenzoyl-a-Dgalactopyranosyl bromide (5). Benzylation of methyl 4,6-0-benzylidene-a-D-galactopyranoside (6) gave the 2,3-dibenzyl ether (7) which was hydrolyzed to 2,3-di-0-benzyl-D-galactose (8). p-Nitrobenzoylation of 8 furnished 2,3-di-O-benzyl-l,5,6-tri-O-p-nitrobenzoyl-(3-~-galactofuranose (9) and an isomer, presumably a (3-pyranose derivative (10). Compound 9 was converted into 2,3-di-0-benzyl-5,6-di-O-p-nitrobenzoyl--~-galactofuranosyl bromide (11) and chloride (12). The new halides 5, 11, and 12 as well as known 2,3,4,6-tetra-0-benzyl-a-Dgalactopyranosyl bromide (1) and chloride (2) were subjected to methanolysis in dichloromethane solution in the presence of methanol alone and in the presence of tetrabutylammonium bromide, mercuric cyanide, and silver tetrafluoroborate, respectively, and the ratios of anomeric glycosides produced were examined by n.m.r. soectroscoov. Factors influencing stereoselectivity %these reactions are discussed. The new methil a-and (3:glycosides derived fcom 5 (13 a n d 14) and the methyl a-glycoside (15) produced from 11 and 12 were isolated, and methyl 2,3,5.6-tetra-0-benzyl-a-D-galactofuranoside (16) was prepared for the first time.

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Section: Preparatiotl Of Fully Benzylated Metlgvl D-galactosidesmentioning

confidence: 91%

Section: Preparatiotl Of Fully Benzylated Metlgvl D-galactosidesmentioning

confidence: 99%

Concerning the Problem of Stereospecific Glycosylation. Synthesis and Methanolysis of some 2-O-Benzylated D-Galactopyranosyl and D-Galactofuranosyl Halides

Fréchet¹,

Baer²

1975

Can. J. Chem.

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“…Addition of sodium hydroxide pellets to a solution of butane-1,4-diol in dimethylsulfoxide (DMSO) followed by treatment with benzyl chloride 22 gave the monoprotected diol (4) in 75% yield. Reaction of (4) with adipic anhydride (3) gave acid (5) in 64% yield.…”

Section: Synthesis/isolation Of Oligomer Intermediatesmentioning

confidence: 99%

Studies of lipase-catalyzed polyesterification of an unactivated diacid/diol system

Binns¹,

Harffey

Roberts

et al. 1998

J. Polym. Sci. A Polym. Chem.

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Preliminary enzymatic polymerization studies in the simple stoichiometric adipic acid/butane‐1,4‐diol system using lipase B from Candida antarctica, immobilized as Novozym 435®, suggest that in solvent‐free conditions a step‐growth mechanism operates involving the sequential addition of an AB synthon by esterification mode only. Conversely, in toluene as solvent there is a change to the more facile transesterification mode in line with the conventional polyesterification procedure, pointing to a change in specificity of the lipase. Evidence is drawn from qualitative studies using a series of synthetic intermediates, enabling authentication of product mixtures together with an indication of the comparative reactivity of species along the proposed reaction pathway. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2069–2080, 1998

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“…Commonly used benzyl donors for benzyl protection are benzyl halides which are toxic, carcinogenic and lachrymose. 22 Our laboratory is actively involved in exploring the chemistry around the indole nucleus to develop useful synthetic methodologies to access indole-based novel molecular structures. In an attempt to C-alkylate the indoline-2-thione nucleus at 3-position using BF 3 etherate and benzyl alcohol, we discovered that a chemoselective S-benzylation had taken place in an excellent yield.…”

mentioning

confidence: 99%