Methyl 3,4-dichloro-3,4-dideoxy

Many other glycosides have been subjected to selective chlorination with sulfuryl chloride. Methyl /3-L-arabinopyranoside afforded methyl 4-chloro-4-deoxy-a-D-xylopyranoside 2,3-di(chlorosulfate) in 29% yield, whereas the a-L anomer gave357 methyl 3,4-dichloro-3,4-dideoxy-/3-i)-ribopyranoside 2-(chlorosulfate) (30%). Methyl /3-d-ribopyranoside was converted into methyl 3,4-dichloro-3,4-dideoxy-a-L-arabinopyranoside through the action of pyridine hydrochloride on its 2,3,4-tri(chlorosulfate).358 Methyl a-D-lyxopyranoside gave only the 2,3,4-tri(chlorosulfate),353 as would be expected from the disposition of its hydroxyl groups, similar to that in the rhamno- and manno-pyranosides. Methyl a-D-altropyranoside was transformed into the 6-chloro-6-deoxy 2,3,4-tri(chlorosulfate) derivative in 80% yield.353... 

Methyl 3,4-di-0-acetyl-2-deoxy-2-iodo-p-D-ribopyranoside, D-270 Methyl 3,5-di-0-benzoyl-2-bromo-2-deoxy-a-D-ribofuranoside, B-92 Methyl 2,3-di-0-benzoyl-5-bromo-5-deoxy-p-D-ribofuranoside, B-93 Methyl 2,4-di-0-benzoyl-3-deoxy-3-iodo-p-L-ribopyranoside, D-271 Methyl 3,5-di-0-benzoyl-2-0-methyl-p-D-ribofuranoside, M-208 Methyl 3,5-di-O-benzoyl-p-D-ribofuranoside, M-208 Methyl 3,5-di-O-benzyl-a-D-ribofuranoside, M-208 Methyl 3,4-dichloro-3,4-dideoxy-p-D-ribopyranoside, D-545 Methyl 2-C-formyl-3,4-0-isopropylidene-p-D-ribopyranoside, F-23 Methyl 3,4-0-isopropylidene-2-0-methyl-p-D-ribopyranoside, M-209 Methyl 2,3-0-isopropylidene-5-5 -methyl-5-thio-p-D-ribofuranoside, T-91 Methyl 2,3-0-isopropylidene-p-D-ribofuranoside, 1-74 Methyl 2,3-0-isopropylidene-p-L-ribofuranoside, 1-74 Methyl 2,3-0-isopropylidene-p-D-ribopyranoside, M-209 Methyl 3,4-0-isopropylidene-p-D-ribopyranoside, M-209 Methyl 2,3-0-isopropylidene-5-thio-p-D-ribofuranoside, T-91 Methyl 2,3-0-isopropylidene-5-thio-p-D-ribopyranoside, T-91 Methyl 3,4-0-isopropylidene-5-thio-p-D-ribopyranoside, T-91... 

Methyl 4,6-dichloro-4,6-dideoxy-a-i>galactopyraiioside, 9CI, 8CI, D-542 Methyl 4,6-dichloro-4,6-dideoxy-p-i> lactopyranoside, D-542 Methyl 4,6-dichloro-4,6-dideoxy-a-D-glucopyranoside, D-543 Methyl 3,4-dichloro-3,4-dideoxy-p-D-ribopyranoside, D-545 Methyl 3,4-dichloro-2,3,4-trideoxy-p-i>gfpcero -pent-2-enopyranoside,... 

An attractive feature in this reaction is the possibility of direct substitution and formation of unblocked sugar derivatives containing one or more chlorodeoxy function in essentially two steps. Another facet is the formation of methyl 4,6-dichloro-4,6-dideoxy-hexosides from certain methyl glycosides in one step. Such compounds could be valuable intermediates in the synthesis of dideoxy and diamino sugars of biological importance. 

Treatment of l,4 3,6-dianhydro-D-glucitol with boron trichloride gives l,6-dichloro-l,6-dideoxy-D-glucitol (20). Although methyl 6-chloro-6-deoxy-a-D-glucopyranoside (isolated as the tribenzoate) could be isolated from the reaction of methyl 3,6-anhydro-a-D-glucopyranoside with boron trichloride (21), the application to the isomeric furanoside derivative led to complex results. 

C7H12C1204 Methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside MCDGAL 31 366... 

CioHi6C1204 Methyl 2,6-dichloro-2,6-dideoxy-3,4-0-isopropylidene-a-D- CDIALT 31 350... 

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%... 

The reaction of sulfuryl chloride with carbohydrates to give chloro-deoxy derivatives has been reviewed briefly in this Series.98 The reaction of sulfuryl chloride with monosaccharides has been shown to afford products in which the secondary hydroxyl groups are replaced by chlorine with inversion of configuration.68-75 Jones and coworkers reported that the reaction of methyl a-D-glucopyranoside with sulfuryl chloride and pyridine in chloroform at room temperature proceeds by way of the 4,6-bis(chlorosulfate) by an Sn2 process, with chloride as the nucleophile, to give methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-bis(chlorosulfate).74... 

It has been found32 that treatment of methyl 4,6-dichloro-4,6-dideoxy-a-D-gaIac-topyranoside 2,3-di(chlorosulfate) (8) with sodium bromide in N,N-dimethyl-formamide at room temperature affords methyl 4,6-dichloro-4,6-dideoxy-o -D-galactopyranoside and its 2- and 3-mono(chlorosulfate) derivatives. These three products were also formed, in addition to a mono(azidosulfate) derivative, when 8 was treated with sodium azide in N,N-dimethylformamide at room temperature. 

An example of the inhibitory effect of a vicinal, axial substituent was provided by the observation25 that, whereas methyl 4,6-dichloro-4,6-dideoxy-/3-D-glucopyranoside 2,3-di(chlorosulfate) readily under-... 

An X-ray crystallographic analysis has been performed44 on methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside prepared by way of reaction of methyl a-D-glucopyranoside with sulfuryl chloride the molecule has the Cl (d) conformation, and the bond distances and valency angles are similar to those in simple sugars. 

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. 

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