Highly Diastereoselective α-Mannopyranosylation in the Absence of Participating Protecting Groups
作者:David Crich、Weiling Cai、Zongmin Dai
DOI:10.1021/jo9910482
日期:2000.3.1
6-di-O-benzyl-3,4-O-(2',3'-dimethoxybutane-2', 3'-diyl)-1-thia-alpha-D-mannopyranoside and its sulfoxide, following activation at -78 degrees C with benzenesulfenyl triflate or triflic anhydride, respectively, provide the corresponding alpha-mannosyl triflate as demonstrated by NMR spectroscopy. On addition of an acceptor alcohol alpha-mannosides are then formed. Similarly, S-phenyl 2,3-O-carbonyl-4, 6-O-benz
S-苯基2,6-二-O-苄基-3,4-O-(2',3'-二甲氧基丁烷-2',3'-二基)-1-硫代-α-D-甘露吡喃糖苷及其亚砜,在-78℃下分别用苯硫基三氟甲磺酸酯或三氟甲磺酸酐活化后,提供相应的α-甘露糖基三氟甲磺酸酯,如NMR光谱所证实的。加入受体醇后,形成α-甘露糖苷。类似地,S-苯基2,3-O-羰基-4,6-O-亚苄基-1-硫杂-α-D-甘露吡喃糖苷和乙基3-O-苯甲酰基-4,6-O-亚苄基-2-O- (叔丁基二甲基甲硅烷基)-1-硫代-α-D-甘露吡喃糖苷均在用苯磺酸亚砜基三氟甲磺酸酯活化后再添加醇而提供α-甘露糖苷。这些结果与可比的糖基化与2,3-二-O-苄基-4的高度β-选择性偶联形成鲜明对比,