A NITRO SUGAR DERIVATIVE ROUTE TO 2-THIOEPISOPHOROSE AND 2-THIOSOPHOROSE AND THEIR REMARKABLE FACILE EPIMERIZATION

摘要

The addition of 1-thio-D-glucose sodium salt to per-O-acetylated 1,2-dideoxy-1-nitro-D-arabino-hex-1-enitol, readily available from D-arabinose, afforded the corresponding 2-S-glycosylated 1-deoxy-1-nitro-D-mannitol and -D-glucitol peracetates. These, after deacetylation, were transformed by the Nef reaction to 2-thioepisophorose and 2-thiosophorose, respectively. The 2-thiodisaccharides easily epimerize in aqueous sodium bicarbonate at ambient temperature to a 1:4 equilibrium mixture. The predominant 2-thiosophorose was obtained crystalline. A H-1 NMR study of the epimerization in deuterium oxide showed that the reaction involves an H-2 proton exchange mechanism. [References: 22]