Thio-sugars. Part VII. Syntheses of trithiocarbonates by reaction of methyl 2,3- and 3,4-anhydroglycopyranosides with sodium methyl xanthate

Abstract

Methyl 2,3-anhydro-4,6-O-benzylidene-α-D-guloside and -taloside, and also the corresponding episulphides, react with sodium methyl xanthate to give methyl 4,6-O-benzylidene-2,3-dideoxy-2,3-thiocarbonyldithio-α-D-idoside. The β-anomers of these eposides and episulphides give the β-form of this ido-trithiocarbonate. Other products include methyl 4,6-di-O-benzylidene-2,3-dideoxy-α- and -β-D-threo-hex-2-enopyranoside, methyl 4,6-di-O-benzylidene-2- and -3-thio-α- and -β-D-idoside, the 3-S-methyl derivative of the 3-thio-β-D-idoside, and dimethyl trithiocarbonate.

Methyl 2,3-dideoxy-4,6-di-O-methyl-2,3-thiocarbonyldithio-α-D-altroside was obtained from methyl 2,3-anhydro-4,6-di-O-methyl-α-D-alloside and -mannoside, and from the corresponding episulphides; the manno-epoxide and the allo-episulphide gave also the gluco-2,3-trithiocarbonate.

Methyl 3,4-anhydro-6-deoxy-α-L-taloside gave methyl 2,3,6-trideoxy-2,3- and -3,4-thiocarbonyldithio-α-L-idopyranoside, whereas methyl 3,4,6-trideoxy-3,4-epithio-α-L-altroside gave methyl 3,4,6-trideoxy-3,4-thiocarbonyldithio-α-L-idoside and -mannoside; the 2-O-methyl ethers of the last two trithiocarbonates were both obtained from methyl 3,4-anhydro-6-deoxy-2-O-methyl-α-L-taloside. Methyl 2,3-anhydro-6-deoxy-α-D-talopyranoside gave methyl 2,3,6-trideoxy-2,3-thiocarbonyldithio-α-D-idopyranoside.

¹ H N.m.r. parameters for the trithiocarbonates and other products are tabulated.