Methyl 4-O-p-tolylsulfonyl

A small number of fluorinated analogs has been prepared without prior protection of the hydroxyl groups, but, owing to the strongly basic conditions prevailing, such reactions as concurrent formation of the 3,6-anhydro derivative (7) may occur, as in the fluorination of methyl 6-O-p-tolylsulfonyl-a-D-glucopyranoside (6) with potassium fluoride in 1,2-ethanediol.77 A previous attempt to use this reaction, in... 

Recent applications of this reaction include the reduction of methyl 3-0-benzyl-2-O-methyl-6-O-p-tolylsulfonyl-a-D-allopyranoside, leading to the synthesis of 6-deoxy-2-0-methyl-D-allose, and the reduction of methyl 3-0-methyl-2,6-di-0-p-tolylsulfonyl-a-D-allopyrano-side as a step in the synthesis of 6-deoxy-3-0-methyl-D-allose. The last-named compound was also synthesized, in lower yield (because of competing side-reactions), starting from methyl 3-0-methyl-2,4,6-tri-0-p-tolylsulfonyl-a-D-allopyranoside. 

The reaction of methyl 2,3-di-0-methyl-6-0-p-tolylsulfonyl-o -D-galactopyranoside (28) with 23 gave the iodide 29 in high yield similar treatment of methyl 2,3-di-0-methyl-6-0-p-tolylsulfonyl-o -D-glucopyranoside (30) afforded the C-4 epimer (31) of58,57 29. These... 

The formation in low yield of 3,6-anhydro-4,5-0-isopropylidene-D-allose dimethyl acetal (82), together with methyl 3-O-p-tolylsulfonyl-D-glucopyranoside (83) as the main product, by the action of boiling 2% methanolic hydrochloric acid (under reflux for 27 hours) on 1,2 5,6-di-O-isopropylidene-3-O-p-tolylsulfonyl-a-D-glucofuranose (81) has been reported.87... 

O-p-tolylsulfonyl-a-D-mannoside (39) in 37% yield. Treatment of (39) with sodium iodide in acetone gave the 6-iodo derivative (40), which underwent reduction with hydrogen in the presence of a nickel boride" catalyst" to give methyl 4-0-benzoyl-2,3-0 carbonyl-6-deoxy-o>-D-manno-side (41) in 95% yield. Reaction of (41) with hydrogen bromide in acetic acid effected replacement of the methoxyl group at C-l, affording crystalline... 

Another method, based on cyclization of glycosyl fluorides,764,765 such as 143 (for a methyl glycoside as a side-product, see Ref. 766), or of 6-O-p-tolylsulfonyl derivatives of hexoses95,97 (145), in alkaline media, was used for the preparation of 2-amino-1,6-anhydro-2-deoxy-/3-D-glucopyranose and its N-substituted derivatives (144). 

The methylsulfonium salt of l,6-anhydro-l(6)-thio-/3-D-glucopyra-nose (240) is apparently an intermediate in the solvolysis of methyl l-thio-6-O-p-tolylsulfonyl-/3-D-glucopyranoside, which involves methyl migration, and results in 6-S-methyl-6-thio-D-glucose.779... 

Methyl 5,6-O-isopropylidene-a-3-O-methyl-2-O-p-tolylsulfonyl-Methyl S,6-0-isopropylidene-/Q-3-O-methyl-2-O-p-tolylsulfonyl-D-Glucopyranose... 

Methoxyl participation, by way of the oxonium ion 191, probably accounts for the ready solvolysis273 (in aqueous acetic acid at 100° for 2.25 hours) of the p-tolylsulfonyl group from 1,2-O-isopropylidene-3,5-di-0-methyl-6-0-p-tolylsulfonyl-a-D-glucofuranose (190). 3,5-Di-O-methyl-D-glucose was obtained in only 39% yield, and a more detailed study of this reaction should prove interesting. 

The direct displacement of secondary sulfonyloxy groups of sugar derivatives by sulfur nucleophiles has received Umited study. Attempted displacement of p-tolylsulfonyloxy groups in methyl 4,6-0-benzylidene-3-O-methyl-2-O-p-tolylsulfonyl-a-D-altropyranoside or 1,2 5,6-di-0-isopro-pylidene-3-O-p-tolylsulfonyl-a-D-glucofuranose, by alkanethiolate anion in an alcohol medium, removed the p-tolylsuKonyl substituent and failed to give any (identifiable) thio sugar product. However, the 2,5-di-methanesulfonate of l,4 3,6-dianhydro-D-mannitol (64) reacted with... 

Methyl a-D-mannopyranoside was treated in succession with p-toluene-sulfonyl chloride, carbonyl chloride, and benzoyl chloride, and, without isolating the intermediates, there was obtained in 37% yield methyl 4-0-l enzoyl-2,3-O-carbony 1-6-0-(p-tolylsulfonyl ) -D-mannoside. The tos-yloxyl group of the latter was replaced by iodine, and hydrogenation of the 6-iodo derivative in the presence of a nickel boride catalyst gave methyl 4-0-benzoyl-2,3-0-carbonyl-6-deoxy- -D-mannoside. Treatment of the latter with hydrogen bromide in acetic acid gave crystalline 4-0-benzoyl-2,3-0-carbonyl-6-deoxy-a-D-mannosyl bromide (8) (16). The... 

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