Thiosugars. VIII. Synthesis of 1, 2-Dithio-β-D-mannopyranose

Abstract

1, 2-Di-S-acetyl-1, 2, -dithio-3, 4, 6-tri-O-acetyl-β-D-mannopyranose (IX) was obtained when a mixture of potassium thiolacetate and one of the 2-bromo-2-deoxy-3, 4, 6-tri-O-acetyl-β-D-glucopyranosyl ethylxanthate (III), 2-bromo-2-deoxy-3, 4, 6-tri-O-acetyl-α-D-glucopyranosyl bromide (IV), 2-O-mesyl-3, 4, 6-tri-O-acetyl-β-D-glucopyranosyl ethylxanthate (VII) or 1-S-acetyl-1-thio-2-O-mesyl-3, 4, 6-tri-O-acetyl-β-D-glucopyranose (VIII) in acetone-ethanol was refluxed for five minutes. The title compound, hygroscopic sirup, [α]²2_D-109.3°→-34°(H₂O), was prepared by deacetylation of IX. Alkaline degradation of III or VII did not afford 1, 2-dideoxy-1, 2-epithio-β-D-mannopyranose, but gave amorphous powders (XVI), m.p. 108∼113°, [α]²8_D+77.8°(CHCl₃) after acetylation of the degradation product. Similarly, 4, 6-O-benzylidene compound of III or VII (XVIII or XX) afforded amorphous powders (XXI), [α]²8_D+111°(CHCl₃). The structures of XVI and XXI were discussed and considered as polymeric products.