Chloro chlorosulfates

SO3 at —78°C converts alkenes to 2-chloro chlorosulfates CICHRCHROSO2CI, which are stable compounds.Chlorine acetate [solutions of which are prepared by treating CI2 with Hg(OAc)2 in an appropriate solvent] adds to alkenes to give acetoxy chlorides.Acetoxy fluorides have been obtained by treatment of alkenes with CH3COOF. ... 

Sulfuryl chloride pyridine Partial replacement of hydroxyl by chlorine via chloro(chlorosulfates)... 

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... 

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... 

D-Lyxose yielded a D-lyxosyl chloride 2,3,4-tri(chlorosulfate) which, on treatment with chloride ion, led to a dichlorodideoxy compound, most probably 2,4-dichloro-2,4-dideoxy-L-arabinose.353 D-Glucose gave a compound presumed to be 4,6-dichloro-4,6-dideoxy-a,/3-D-galactosyl chloride 2,3-di(chlorosulfate),360 and D-xylose afforded a monochloromonodeoxy derivative formulated, on indirect evidence, as 4-chloro-4-deoxy-L-arabinopyranosyl chloride 2,3-di(chlorosulfate).360 3,4-Dichloro-3,4-dideoxy-/3-D-ribopyranosyl chloride 2-(chlorosulfate) was the major, and 4-chloro-4-deoxy-a-D-xylopyranosyl chloride 2,3-di(chlorosulfate) the minor, product from the reaction of L-arabinose with sulfuryl chloride at room temperature for 24 hours.357,361 It has been established that, on reaction with sulfuryl chloride at low temperature, crystalline a-D-xylopyranose and /3-D-lyxopyranose afford, respectively, the 2,4,6-tri(chlorosul-fate)s of /3-D-xylopyranosyl chloride and a-D-lyxopyranosyl chloride,362 363 confirming that substitution at C-l occurs by an Sn2 process on a l-(chlorosulfuric) ester intermediate. 

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... 

An elegant, stereospecific synthesis of two 2-chloro-2-deoxy-pentoses was achieved during the course of a study of the anomerization of chlorosulfated glycosyl chlorides.40 It had been found37 that attempts to anomerize /3-D-xylopyranosyl chloride 2,3,4-tri(chloro-sulfate) (14) with 0.25 mol-equivalent of aluminum chloride afforded the crystalline a-D anomer only in low yield formed also was another compound whose structure has been established40 to be that of 2-chloro-2-deoxy-a-D-lyxopyranosyl chloride 3,4-di(chlorosulfate) (16). The dichloro derivative 16 became the exclusive product when 1.5 mol-equivalents of aluminum chloride were used treatment of 16 with sodium iodide yielded crystalline 2-chloro-2-deoxy-D-lyxose. Similarly, a-D-lyxopyranosyl chloride 2,3,4-tri(chlorosulfate) (15) afforded 2-chloro-2-deoxy-a-D-xylopyranosyl chloride 3,4-di(chlorosuI-fate) (17). 

Another example of the p-trans-axial substituent effect is provided by the reaction of methyl ot-D-mannopyranoside 26 with sulfuryl chloride, which gave methyl 6-chloro-6-deoxy-a-D-mannopyranoside 2,3,4-tri(chlorosulfate) 26a even treatment of the product with pyridinium chloride for 12 h at 50°C did not effect further substitution [41] (Scheme 6). 

B. Helferich, Uber zwei neue Derivate von- -und (3-Methyl Glucosid, Chem. Ber. 56 1082 (1921). H. J. Jennings and J. K. N. Jones, Reactions of sugar chlorosulfates. (V). Synthesis of chloro-deoxy sugars. Can. J. Chem. 43 3018 (1965). 

The chlorosulfated glycosyl chloride 60 is converted into 2-chloro-2-deoxy-a-D-lyxopyra-nosyl chloride 61 when treated with aluminum chloride (O Scheme 34) [58]. This reaction proceeds via an initial intramolecular displacement of chlorosulfate at C-2 by the anomeric chlorine atom, followed by the chloride ion attack at the more highly reactive center (C-1). Pyranoid derivatives having a chlorosulfonyloxy group in a frawi -diaxial relation with a ring proton, such as 62, may undergo an elimination reaction to yield the unsaturated compound 63 (O Scheme 35) [59]. 

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