Allopyranoside methyl 3,6-dichloro-3,6-dideoxy

Reactivity at 0-3, in addition to that at 0-4 and 0-6, was observed with methyl )3-D-galactopyranoside, which, when treated with sulfuryl chloride, yielded methyl 3,4,6-trichloro-3,4,6-trideoxy-/J-D-allopyranoside 2-(chlorosulfate) in 56% yield.352 In contrast, under similar conditions, methyl a-D-galactopyranoside gave352 methyl 4,6-dichloro-4,6-dideoxy-a-D-glucopyranoside 2,3-di(chlorosulfate). Further examples of the dependence of the reactivity on the configuration of C-l are the conversion of methyl 4,6-0-benzylidene-/3-D-glucopyranoside into methyl 4,6-0-benzylidene-3-chloro-3-deoxy-/3-i>allopyranoside by sulfuryl chloride,352 and of methyl 4,6-0-benzylidene-a-D-glucopyranoside, under similar conditions, into the 2,3-di(chlorosulfate).355... 

An important step in the synthesis of paratose (3,6-dideoxy-n-rtfoo-hexose) involved the conversion of methyl 3-chloro-3-deoxy-/8-D-allopyranoside into methyl 3,6-dichloro-3,6-dideoxy-/8-D-allo-pyranoside in 33% yield.359... 

On treatment with 30 equivalents of methanesulfonyl chloride in N,N-dimethylformamide for 8 days at 65°, methyl /3-maltoside gave a mixture of methyl 3,6-dichloro-4-0-(6-chloro-6-deoxy-a-D-glucopyranosyl)-3,6-dideoxy-/3-D-allopyranoside, isolated in 46%... 

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. 

A solution of methyl 3,6-dichloro-3,6-dideoxy-p-D-allopyranoside [47] (25, 1.0 g) in ethanol (30 mL) containing W-4 Raney nickel catalyst [27,58] (20 mL ethanol slurry) and triethylamine (1.3 mL) was subjected to a hydrogen pressure of 45 psig for 36 h. TLC [Silica Gel G, Brinkmann 2 1 (v/v) ethyl acetate-petroleum ether (bp 60°-80°C)] showed that the starting material (R 0.42) had all reacted and revealed the presence of a new component having an Rf of 0.23. The filtered solution was concentrated to a syrup, which... 

A solution of methyl 4,6-Obenzylidene-3-chloro-3-deoxy-P-D-allopyranoside [29] (33, 2.45 g) in acetone (40 mL) and 0.2 N hydrochloric acid (13 mL) was heated at reflux temperature for 4 h. The acetone was removed by distillation, and the aqueous solution was neutralized with Duolite A-4(OH ) ion-exchange resin and concentrated to yield methyl 3-chloro-3-deoxy-p-D-allopyranoside as a chromatographically homogeneous (TLC) syrup [41] (1.56 g), Rt 0.5 [6 2 1 (v/v/v) 1-butanol-ethanol-water], [a]D —49° (c 1.0, H20). This syrupy product (1.39 g) was converted into methyl 3,6-dichloro-3,6-dideoxy-p-D-allo-pyranoside 25 as described by Cottrell et al. [44J. The crystalline product was recrystallized from chloroform-petroleum ether to give the final product (0.5 g, 33%) mp 162°-163°C, [a]D -43° (c 0.6, CHClj) reported [44] mp 154°-156°C, [a]D -45° (c 1.0, CHC13). 

A solution of methyl 3,6-dichloro-3,6-dideoxy-p-D-allopyranoside (25, 148 mg) in ethanol (50 mL) containing potassium hydroxide (70 mg) and W-4 Raney nickel [27,58] (40 mg) was shaken in an atmosphere of hydrogen for 2 days. A solid product was isolated in the usual manner recrystallization from ethyl acetate-petroleum ether gave methyl 3,6-dideoxy-P-D-nbo-hexopyranoside (35, 89 mg, 86%) mp 63°-65°C, [a]D —60° (c 1.5, MeOH). A solution of methyl 3,6-dideoxy-p-D-ribo-hexopyranoside (35, 86 mg) in 1 N sulfuric acid (10 mL) was heated at 90°C for 5 h. The cooled solution was neutralized with Duolite A-4(OH ) iou-exchange resin and concentrated to yield paratose 36 as a homogeneous (TLC) syrup (61 mg, 78%) R 0.21 [Silica Gel G 6 1 (v/v) chloroform-methanol], [a]D +7° (c 1.1, HzO), in agreement with values reported previously [61,62] for paratose. 

G. Reductive Dechlorination of Methyl 3,6-Dichloro-3,6-dideoxy- 3-D-allopyranoside [60]... 

A special example of epoxide opening reaction is outlined in O Scheme 40. Methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside 72 gives the 2-chloro-2-deoxy-3-0-formyl-altroside 73 on treatment of (chloromethylene)dimethyliminium chloride at room temperature. Alternatively, when the reaction mixture is heated for a longer time, methyl 3,4-0-benzyli-dene-2,6-dichloro-2,6-dideoxy-a-D-altroside 74 is obtained by means of a rearrangement of the benzylidene group [51]. 

Methyl 2,3-di-0-benzyl-5-0-trityl-a-L-arabinofuranoside, M-152 Methyl 2,3-di-0-benzyl-5-0-trityl-p-L-arabinofuranoside, M-152 Methyl 2,3-di-O-benzyl-6-0-trityl-a-D- cy/o-hexopyranosid-4-ulose, H-I04 Methyl 2,3-di-0-benzyl-4-0-trityl-p-D-xylopyranoside, M-217 Methyl 3,6-dibromo-3,6-dideoxy-p-D-allopyranoside, D-523 Methyl 2,4-dibromo-2,4-dideoxy-L-erythronate, D-541 Methyl 3,6-dibromo-3,6-dideoxy-p-D-glucopyranoside, D-532 Methyl 2,4-dibromo-2,4-dideoxy-D-threonate, D-541 Methyl 2,4-dibromo-2,4-dideoxy-L-threonate, D-541 Methyl 4,6-dichloro-4,6-dideoxy-2,3-di-0-tosyl-a-D-galactopyranoside, D-542... 

Metltyl 2,4-di-0-ben2 yl-3-bromo-3 deoxy-(3-D-arabinopyranoside, B-63 Methyl 2,4-di-0-benzoyl-3-bromo-3-deoxy-a-D-lyxopyranoside, B-83 Methyl 2,5-di-0-ben2 yl-3-bromo-3-deoxy-a-D-xylofuranoside, B-103 Methyl 2,5-di-0-ben2 yl-3-bromo-3-deoxy-(3-D-xylofuranoside, B-103 Methyl 2,4-di-0-benzoyl-3-deoxy-3-iodo-p-L-ribopyranoside, D-271 Methyl 3,6-dibromo-3, dideoxy-(3-D-allopyranoside, 9CI, D-523 Methyl 3,6-dibromo-3,6-dideoxy-(3-D-glua>pyranoside, 9CI, D-532 Methyl 3,4--glycero -pent-2-enopyranoside,... 

Treatment of methyl 3,6-dichloro-3,6-dideoxy-p-D-allopyranoside with lithium chloride in NJ -dimethylacetamide at 80°-100°C results in an equilibrium mixture of starting material and methyl 3,6-dichloro-3,6-dideoxy-P-D-glucopyranoside with the gZ co-isomer predominating. ... 

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