BRIDGED DERIVATIVES OF SUCROSE: THE SYNTHESIS OF 6,6'-dithiosucrose, 6,6'-epidithiosucrose, and 6,6'-epithiosucrose

Article abstract of DOI:10.1016/0008-6215(88)85088-2

Selective iodination and bromination of sucrose at C-6 and C-6' has been accomplished by reactions with iodine-triphenylphosphine-imidazole and carbon tetrabromide-triphenylphosphine-pyridine, respectively.Substitution of the bromo groups in 6,6'-dibromo-6,6'-dideoxysucrose hexa-acetate by CNS(1-), AcS(1-), and Me2NCS2(1-) took place without complications, but when EtOCS2K was used, a complex reaction sequence took place leading to 6,6'-epithiosucrose hexa-acetate.Similarly, reaction of the dibromo derivative with K2CS3 afforded mainly the 6,6'-episulphide together with 6,6'-epidithiosucrose hexa-acetate, which was also formed from the dibromide by sequential treatment with thiourea and sodium metabisulphite.Oxidation of the episulphide with sodium metaperiodate afforded solely the (R)-sulphoxide, and oxidation with hydrogen peroxide afforded the sulphone.The episulphide, the episulphide S,S-dioxide, and the episulphide all showed conformational instability of the ring containing the sulphur atom(s), as indicated by the n.m.r. spectra, but the episulphide S-oxide did not show this behaviour.