3‐Desoxy‐ d ‐mannose. Desoxyzucker. 11. Mitteilung

Methyl 4,G-O-benzylidene-2-be1izylthio-2-deosy-or-~-altropyranoside and methyl l,(j-0-benzylidene-3-benzylthio-3-deoxy-or-~-altropyraosid have been prepared by the reaction of sodi~tlu benzylmercaptide with methyl 3,3-anhyclro-4,G-O-be11zylidene-a-n-allopyratoide and methyl 2,3-anhydro-4,6-0-benzylidene-a-~-1nan11opyra11oside respectively.These two thio ethers were successfully reduced by sodium in l i q~~i d ammonia to methyl ~-deoxy-2-t11ercapto-or-~-altropyranoside and methyl 3-deosy-3-tnercapto-or-D-altropyranoside. A n attempted replacement of the tosyl group in 1,2;5,U-cli-0-isopropylidene-:M-tosyl-or-~-glucofuranose by benzyl mercaptan was uns~~ccessful. INTRODUCTIOSThe preparation of non no saccharides in which an oxygen atom has been replaced by a sulphur atom has received renewed attention in recent years, primarily due to the fact that these co~npounds provide a route to the synthesis of deoxy sugars. A review by Raymond covering the literature on thio sugars to 1944 (1) refers t o the preparation of a number of thioglycosides and w-deoxy-w-alkylthio-hexoses and -pentoses. The only monosaccharide mentioned which contained a free mercapto group on a carbon atoll1 other than the anomeric carbon ( 2 4 ) was a substance clescribed as "3-deoxy-3-mercapto-D-glucose" obtained by Freudenberg and Wolf (5) in their attempt t o apply the Tschiigaeff reaction (6) to the preparation of an unsaturated monosaccharide.Since 1944, a considerable amount of work has appeared in this area, but primarily concerning the preparation of the thioglycosides and thio ethers of monosaccharides (7-12). A few reports have been ~n a d e of the preparation of monosaccharides with a free nlercapto group. An improved synthesis of 1-thio-D-glucose by the reaction of hydrogen sulphide with l,2-anhydro-D-glucose and its 3,3,G-tri-0-acetate in dimethylformamide has been clescribed (13). The reduction with lithium aluminum hydride of 5,G-dideoxyd,G-epithio-l,2-O-isopropylicle1~e-~-~-iclose has yielded 5,0-dideoxy-5-mercapto-L-idose (14). There has also been reported the preparation of 5,G-clideoxy-1,2-0-isopropylidene-5,G-(t11iocnrbonyldithio)-p-L-idose, a compound wi~ich, no doubt, can be reduced readily to 5,G-dideoxy-1,2-O-isopropylidene-5,G-climercapto-~-~-idose with lithium alumini~m hydride in accordance with similar reductions carried out on the trithiocarbonates of seine hexitols (14,15).Since a number of mercapto monosaccharicles were required in this laboratory, a program for their preparation was begun. This paper presents some results obtained in this direction. RESULTS .ASI> DISCGSSIOSThe debenzylation of S-benzylcysteine has been accomplished by the use of sodiunl in liquid ammonia (lG) and this technique has been successfully applied in this laboratory to the preparation of ~nercaptoindoles (17). These results suggested that mercapto monosaccharides might be prepared by the reaction of beilzyl mercaptan with suitable anhydro monosaccl~arides followed by the reductive cleavage of the resulting benzylthio ethers with sodium in...

Section: Results Asi> Discgssiossupporting

confidence: 84%

Section: Results Asi> Discgssiosmentioning

confidence: 99%

See 1 more Smart Citation

The Preparation of Some Mercapto Monosaccharides

Jamieson¹,

Brown²

1961

“…Thus, methyl 4,6-O-benzylidene-a-~-erythro-hex-2-enopyrai10-side was first prepared by Bolliger and Prins (22) from methyl 4,6-0-benzylidene-3-deoxy-2-0-ptoluenesulfonyl-a-D-mannopyranoside. This compound has since beell prepared in a variety of other ways including epoxide (23), iodohydrin (24), episulfide (25,26), thionocarbonate (26), sulfonate (26,27), xanthate (16), thiouronium (28), and aziridine (29) intermediates.…”

mentioning

confidence: 99%

Preparation of unsaturated carbohydrates. A facile synthesis of methyl 4,6-O-Benzylidene-D-hex-2-enopyranosides

Lemieux¹,

Fraga²,

Watanabe³

1968

104

A simple method was explored for the preparation of methyl 4,6-0-benzylidene-hex-2-enopyranosicles. Methyl 2,3-anhydro-4,6-0-benzylidene-D-hexopyranosides were converted to diaxial iodohydrins using sodium iodide in acetone which contained sodium acetate and acetic acid. Trcatment of the iodohydrins with either methane-or p-toluenesulfonyl chloride in refluxing pyridine yielded the 2,3-unsaturated derivative in excellent yield. The four isomers for methyl 4,6-0-benzylidene-D-hex-2-enopyranoside were thus prepared. The rotations of the anomeric pairs followed Hudson's rules of isorotation. Evidence is provided that, in the absence of strong destabilizing interactions in the product, the epoxide ring of one of the above-mentioned 2,3-anhydroglycosides is opened by lithium iodide in ether to form the iodohydrin as the lithium alkoxide in high yield. This observation provides an explanation for the reduction of methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside to 4,6-0-benzylidene-D-allal. Reaction of methyl 4,6-0-benzylidene-2-deoxy-2-iodo-~-~-idopyranoside with methyl lithium provided 4,6-0-benzylidene-D-gulal. The conformational properties of a number of the compounds prepared and of acetylated methyl pentopyranosides, as derived from their nuclear magnetic resonance parameters, are discussed with particular reference to the role that geminal coupling constants may play in the determination of configuration and conformational equilibria.

“…Similarly, in methyl 4,6-0-benzylidene-a-D-glucopyranoside (I) the hydroxyl a t C? is more reactive in substitution reactions than that a t C3 (8)(9)(10)(11). When I was treated with 1 mole of (benzy1thio)-carbonyl chloride in pyridine solution, the 2-thiocarbonate derivative was isolated in 58% yield together with 10yo of the disubstituted product, methyl 4,6-0-benzj-lidene-2,3-di-0-(benzylthio)carbonyl-a-~-glycopyranoside.…”

Section: Discussionmentioning

confidence: 99%

THE METHYL 2-O- (BENZYLTHIO)CARBONYL DERIVATIVE AS A PRECURSOR TO PARTIAL ESTERS OF METHYL α-D-GLUCOPYRANOSIDE

Willard¹,

Sadowski²,

Vitale³

1963

The utility of the thiocarbonyl group for blocking the Cz hydroxyl in methyl glucosides has been demonstrated. Methyl 2-0-(benzy1thio)carbonyl-a-D-glucopyranoside has been synthesized in good yield and its structure proved. Use of this 2-0-thiocarbonyl derivative in conjunction with acid-labile blocking groups has permitted the first syntheses of the following esters of methyl a-D-glucopyranoside: 3-0-benzoyl-, 3,4-di-0-benzoyl-, and 3,4,6-tri-0-benzoyl-, and the crqstalline 2-0-(p-to1uene)sulphonate derivative of each.