Fructose 1-0-trityl

Methylation of verbascose, and hydrolysis, gave21 2,3,4,6-tetra-O-methyl-D-galactose (identified as the crystalline anilide), 2,3,4-tri-O-methyl-D-galactose (crystalline, identified by converting it into the 6-0-trityl derivative), 1,3,4,6-tetra-O-methyl-D-fructose (identified by analytical data and by its optical rotation), and a tri-O-methyl-D-glucose which, on further methylation, was converted into 2,3,4,6-tetra-O-methyl-D-glucose (identified through the crystalline anilide). 

Another crystalline tetraacetate of fructose was obtained by Helferich and Bredereck78 by the acetylation, followed by detritylation, of 1-trityl-D-fructose (see page 82). This at first was considered to be D-fructopyranose 2,3,4,5-tetraacetate from its method of preparation and from... 

The only dimethyl-D-fructose which has been characterized, 3,4-di-methyl-D-fructose, has been prepared by McDonald and Jackson141 from di-D-fructose anhydride I. Tritylation of this anhydride gives the 6,6 -ditrityl derivative which is methylated to 3,4,3, 4 -tetramethyl-6,6 -di-trityl-di-D-fructose anhydride I. Removal of the trityl groups followed by hydrolysis yields liquid 3,4-dimethyl-D-fructose, [ ]d —60.66° in water. It has also been obtained, with 4-methyl-D-fructose, from the hydrolysis of methylated di-D-fructose anhydride III. The structure of this dimethyl-D-fructose follows from its method of preparation from di-D-fructose anhydride I whose structure is known.10 McDonald and Jackson also prepared 3,4-dimethyl-D-fructose from inulin by the following method inulin — monotrityl inulin — monotrityl inulin diacetate — dimethyl monotrityl inulin — dimethyl isopropylidene-D-fructose — methyl dimethyl-D-fructoside —> 3,4-dimethyl-D-fructose. Its structure was confirmed by its oxidation without loss of methyl to the same lactol of the dimethyl dibasic acid obtained from 1,3,4-trimethyl-D-fructose (see page 78). The phenylosazone made from 3,4-dimethyl-D-fructose has m. p. 126° that from 3,4-dimethyl-D-glucose has not been recorded. 

One monotrityl-D-fructose has been prepared. By treating D-fructose with an equimolecular amount of trityl chloride in pyridine for one day at room temperature, Helferich and Bredereck78 obtained a 12% yield of crystalline 1-trityl-D-fructose, m. p. 170°, [ ]d —26.2° — +4.2° in pyridine. Proof of structure of this compound depends on the preparation of fceto-D-fructose 3,4,5,6-tetraacetate, already discussed (page 63). 

Reaction of D-fructose with two molecular proportions of trityl chloride in pyridine for two days at room temperature gave a ditrityl-D-fructose (30% yield), which crystallized (m. p. 96-97°) with two molecules of pyridine. Removal of the pyridine left amorphous ditrityl-D-fructose, [a]D +17.5° in chloroform. This gave a crystalline oxime identical with that obtained by tritylating D-fructose oxime. Helferich148 designates this ditrityl derivative as 1,6-ditrityl-D-fructose without further proof. 

Trityl- 8-D-mannose, hih -ditrityltrehalose, and 1,6-ditrityl-n-fructose were prepared later. All these trityl ethers of free sugars contained solvent of crystallization. Ditritylfructose crystallized with two molecules of pyridine, and 1,6-ditrityldulcitol with two molecules of pyridine hydrochloride. ... 

For ethyl D-fructofuranoside, both anomers are formed in small proportion during the hydrogenolysis of sucrose in ethanol. When the reaction was performed at 100° in an atmosphere of argon, considerable quantities were obtained. Ethyl S-D-fructofuranoside, [ ]d —36° (in water), is readily hydrolyzed to D-fructose by invertase (and also by 0.1 N sulfuric acid) at room temperature. The same behavior was observed for a substance isolated from wheat germ. Acetylation yielded a sirupy product, but treatment with trityl chloride gave crystalline methyl 1,6-di-O-trityl-D-fructoside (m.p. 180-183°). With p-toluenesulfonyl chloride, a crystalline product is obtained, with m.p. 125-127°. Ethyl a-D-fructofuranoside ([ ]d +65°, in water) is not attacked by invertase. Tritylation, followed by acetylation, gives ethyl 3,4-di-O-acetyl-l, 6-di-O-trityl-ai-D-fructofuran-oside m.p., 142-144° and [q ]d +44.5° (in chloroform). 

A most important theoretical study was presented by Hennig on the possible reaction-mechanisms involved in the formation of cyclic and keto derivatives during acetylation (see Scheme III). When 1 mole of 3,4,5-tri-0-acetyl-l,6-di-0-trityl-fcefo-D-fructose (a) is treated at room temperature with two moles of acetyl bromide in acetic anhydride, 1,3,4,5-tetra-... 

Bredereck and coworkers also studied the 1,6-ditrityl ether, and definite proof of its structure was afforded by an outstanding series of experiments. The amorphous material (m.p. 94r-96°) was treated with the ordinary acetylation mixture, and yielded 3,4,5-tri-O-acetyl-l,6-di-O-trityl-fce(o-D-fructose. Preparation of the oxime followed by further acetylation gave the crystalline acetate of the oxime [ m.p. 207-208° Ca ]D - -118° (in chloroform)]. < The oxime of l,6-di-t>-trityl-D-fructose affords the same product on acetylation. The keto form was proved by formation of the crystalline diethyl dithioacetal from the acetyl derivative. 

Another crystalline material (m.p. 165°), probably the furanoid form, was obtained when sodium acetate and acetic anhydride were used for acetylation of 1,6-di-O-trityl-D-fructose, and treatment of the product with hydroxylamine resulted in splitting of one acetyl group. A monotrityl (m.p. 150-153°) and a ditrityl ether (m.p. 221-226°) were prepared from... 

Benzyl 3-bromo-3-deoxy-2-0-methyl-p-D-xylopyranoside, B-103 Benzyl 3-bromo-3-deoxy-4-0-methyl-p-D-xylopyranoside, B-103 Benzyl 3-deoxy-3-fluoro-p-D-glucopyranoside, D-89 Benzyl 3-deoxy-3-iodo-p-L-xylopyranoside, D-280 Benzyl 2,4-di-D-benzoyl-3-bromo-3-deoxy-a-D-xylopyranoside, B-103 Benzyl 2,4,6-tri-D-acetyl-3-deoxy-3-fluoro-p-D-glucopyranoside, D-89 1 - O -Benzyl-3-deoxy-3-fluoro-D-fructose, D-74 3-Bromo-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose, B-56 3-Bromo-3-deoxyglucose D-form, B-75 3-Bromo-3-deoxymannose D-form, B-88 3 -Bromo-3 -deoxythymidine 5 -Trityl, B-99 3 -Bromo-3 -deoxythymidine, B-99... 

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