Allopyranoside, methyl 2,3-anhydro

The Action of Alkali on Methyl 2 3-Anhydro-a-D-allopyranoside and l 5-Anhydro-2-deoxy-3-0-toluene-p-sulphonyl-D-arabino-hexitol," A. B. Foster, M. Stacey, and S. V. Vardheim, Acta Chem. Scand., 12(1958) 1819-1824. 

C17H23Br09 Methyl 2,3-anhydro-6-bromo-6-deoxy-4-0-(4,6-di-0-ace-tyl-2,3-dideoxy-a-D-erythro-hex-2-enopyranosyl)-a-D-allopyranoside (MBEHAP)98... 

In the aldohexopyranose series, treatment of methyl 2,3-anhydro-4,6-di-O-methyl-a-D-allopyranoside (34), or of the corresponding 4,6-diacetate (39), with hydrogen tetrafluoroborate in hydrogen fluoride at 70° afforded121 the corresponding derivatives of 2-deoxy-2-fluoro-D-al-tropyranosyl fluoride (35 and 40) and 3-deoxy-3-fluoro-D-glucopyrano-syl fluoride (36 and 41). Compounds 35 and 36 were hydrolyzed, and... 

A novel method of opening of oxiranes involves the use of (chlo-romethylene)dimethyliminium chloride (39) [see Section II,2c p. 250], monochlorodeoxy or dichlorodideoxy derivatives are obtained, depending upon the reaction conditions employed.83 Thus, methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside (110) reacts with 39 in 1,1,2,2-tetrachloroethane at room temperature to give, upon hydrolysis of the primary adduct 111 with an aqueous solution of sodium hydrogen carbonate, methyl 4,6-0-benzylidene-2-chloro-2-deoxy-3-0-formyl-a-D-altropyranoside (112). If a solution of 39 and 110 in 1,1,2,2-tetrachloroethane is heated at reflux temperature, methyl 3,4-0-benzylidene-2,6-dichloro-2,6-dideoxy-o -D-altropyrano-side (113) is obtained in high yield the n.m.r. spectrum of 113, like that of 47 (see Section II, 2c p. 250), showed the presence of two diastereoisomers which differed in the configuration of the benzyl-idene-acetal carbon atom. 

With sodium hydroxide, methyl 2,3-anhydro-a-D-allopyranoside yields methyl 3,6-anhydro-a-D-glucopyranoside by intramolecular attack on the epoxide ring by the 6-hydroxyl group.72 Methyl 2,3-anhydro-a-D-gulopyranoside behaves similarly, and its intermediacy accounts for the conversion of methyl 3,4-anhydro-a-D-galactopyrano-side into methyl 3,6-anhydro-a-D-galactopyranoside on treatment with alkali.67... 

The racemic form of methyl 3,4-anhydro-/3-mycaroside (82) has been synthesized 35 it is an epoxide of a branched-chain sugar having the oxirane ring fused to the pyranose ring. Hydrolysis of the oxirane ring with hydrochloric acid in aqueous p-dioxane occurs with substitution at C-4, the (more accessible) secondary position, as would be expected from its favored °H, conformation (82) anticipated, because it is an analog of the 3,4-anhydro-D-allopyranoside derivatives considered previously (see p. 148). 

As might be expected, the nitrous acid deamination of methyl 2-amino-4,6-0-benzylidene-2-deoxy-a-D-altropyranoside (10) hydrochloride leads45,46 uniquely to methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside (11). The benzylidene group does not play an... 

M. Sharma and R. K. Brown, The mechanism of the reaction of methyllithium with 2,3-anhydro-4,6 () ben/.ylidcnc-a-n-allopyranoside to form 4.6-(l-bcn/ylidcnc 1,2-didehydro-1,2-dideoxy-2-methyl-D-nbo-hexopyranose, Can. J. Chem. 46 151 (1968). 

J. W. Rrajewski, P. Gluzinski, and A. Banaszek, Crystal and molecular structure of methyl 3,4-anhydro-a-DL-allopyranoside ring conformations in the 3,4-anhydropyranose system, Carbohydr. Res., 203 (1990) 195-203. 

H. W. C. Raaijmakers, B. Zwanenburg, and G. J. F. Chittenden, An alternative synthesis of methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside using carbonate esters, Carbohydr. Res., 238 (1993) 185-192. 

Treatment of an epoxide, namely methyl 2,3-anhydro-4,6-0-benzylidene-oi-D-allopyranoside (78, Scheme 21), with nitryl iodide using methanol as the solvent has been reported.123 Rather than the expected nitration, opening of the epoxide occurred to afford 30% of methyl 4,6-0-benzylidene-3-0-methyl-oi-D-glucopyranoside (79), 10% of methyl 4,6-0-benzylidene-2-0-methyl-a-D-altropyranoside (80), and a water-soluble material. The water-soluble material was later determined to be a mixture of the 2-0- (81) and 3-0-methyl (82) products, with the benzylidene acetal removed, a result consistent with a later study.124 Performing the reaction in the absence of the silver salt resulted solely in formation of the water-soluble product. The preponderance of the diequatorial product 81 is in violation of the Flirst-Plattner rule, which predicts more of the diaxial product. The authors explanation for the anti-Fiirst-Plattner addition is as follows. 

Very significant results have been reported"sodium hydride. The resultant cyclopropane derivative (238a) was... 

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