nucleophile, and silver perchlorate as the promoter. The n.m.r. spectra (1H- and 13C-) of numerous synthetic intermediates were analyzed and completely assigned by a variety of two-dimensional homo- and hetero-nuclear n.m.r.-spectroscopic techniques, and the final deprotected title oligosaccharides were characterized by 13C-n.m.r. data. Silver perchlorate-mediated glycosylation reactions involving beta-glycosyl
1,6-脱
水-2,3,4-三-O-苄基-β-
D-吡喃葡萄糖的酸催化
硫酚氧化反应和所得苯基2,3,4-三-O-苄基-1-
硫代-
苯甲酸乙酰化α-
D-吡喃葡萄糖苷(4)得到苯基6-O-乙酰基-2,3,4-三-O-苄基-1-
硫代-α-
D-吡喃葡萄糖苷(5)。5与
氯的反应立体定向产生相应的β-糖基
氯,将其在
高氯酸银和2,4,6-三
甲基吡啶的存在下用4处理,得到苯基O-(6-O-乙酰基-2,3 ,4-三-O-苄基-α-
D-吡喃葡萄糖基)-(1-6)-2,3,4-三-O-苄基-1-
硫代-α-
D-吡喃葡萄糖苷(17)。结晶O-(6-O-乙酰基-2,3,4-三-O-苄基-α-
D-吡喃葡萄糖基)-(1 ---- 6)-2,3,4-三-O-苄基- β-
D-吡喃葡萄糖基
氯,可以通过用
氯处理以立体特异性的方式容易地从17中获得,在异麦芽
寡糖,直至并包括八糖的甲基糖苷的嵌段合成中,“苯丙
氨酸”用作关键糖基(
异麦芽糖基)供体。通过使用SnCl2活化的2