Thio-sugars. Part II. The thiofuranose ring

Abstract

4,6-Dideoxy-4-mercapto-L-talofuranose, a sugar in which the oxygen atom of a normal furanose ring is replaced by sulphur, has been synthesised from L-rhamnose.

In contrast to the complete resistance towards replacement by thio substituents of the sulphonyloxy group in methyl 2,3,6-tri-O-acyl-4-O-tosyl-(or methanesulphonyl-)β-D-galactosides, both sulphonyloxy groups in methyl 4,6-di-O-methanesulphonyl-2,3-di-O-methyl-β-D-galactoside are readily replaced by reaction with potassium thiolacetate, and both are also attacked by sodium iodide. Methyl 6-deoxy-4-O-methanesulphonyl-2,3-di-O-methyl-β-D-galactoside is also reactive, and yields a 4-acetylthio-compound which on acetolysis gives 1,5-di-O-acetyl-4,6-dideoxy-4-mercapto-2,3-di-O-methyl-D-glucofuranose, another compound of the thiofuranose type.

1,6-Anhydro-4-deoxy-2,3-O-isopropylidene-4-mercapto-β-D-mannose has been synthesised from 1,6:3,4-dianhydro-β-D-talose.