Characterization and interconversions of 2-S-ethyl-2-thio-d-mannose diethyl dithioacetal and the facile epimerization of 2-thio-d-mannopyranose derivatives
作者:Derek Horton、Peter Norris、Bertold Berrang
DOI:10.1016/0008-6215(95)00399-1
日期:1996.3
3,4,5,6-Tetra-O-benzoyl-D-glucose diethyl dithioacetal (2) reacts with ethanethiol under acidic conditions to afford 3,4,5,6-tetra-O-benzoyl-2-S-ethyl-2-thio-D-mannose (3), the stereochemistry at C-2 of which has been assigned by chemical conversions on its debenzoylated derivative, the crystalline 2-S-ethyl-2-thio-D-mannose diethyl dithioacetal (4). In the presence of mercuric chloride (1.1 molar
3,4,5,6-四-O-苯甲酰基-D-葡萄糖二乙基二硫缩醛(2)在酸性条件下与乙硫醇反应生成3,4,5,6-四-O-苯甲酰基-2-S-乙基- 2-硫代-D-甘露糖(3),其C-2的立体化学是通过其脱苯甲酰化衍生物(2-S-乙基-2-硫代-D-甘露糖二乙基二硫缩醛)的化学转化来确定的(4) 。在氯化汞(1.1摩尔当量)的存在下,4转化为结晶的2-S-乙基-1,2-二硫代-α-D-甘露呋喃糖苷(5)。4的完全脱汞得到糖浆2-S-乙基-2-硫代-D-甘露吡喃糖(6),其特征为苯hydr 7和结晶的α-吡喃糖四乙酸酯9。用氯化汞和碳酸氢钠水溶液进一步处理4导致分离出6,以及其结晶2准分子,2-S-乙基-2-硫代-β-D-吡喃葡萄糖(10)。6的再巯基化得到甘露糖基二乙基二硫缩醛4作为主要产物,而类似的10处理则产生2-S-乙基-1,2-二硫代-α-D-吡喃葡萄糖苷乙基(13)。已经研究了2转化为3