作者:Matthias Kreuzer、Joachim Thiem
DOI:10.1016/s0008-6215(00)90057-0
日期:1986.7
mainly the α-(1→6) anomer was formed. These model systems were used to elucidate the limiting conditions for this procedure, and mechanistic conceptions are discussed. By glycosylation at O-4 of 1,6:2,3-dianhydro-β- d -mannopyranose (11) with the perbenzylated α-fluoride 10 both the α- and the β- d -(1→4) disaccharide derivatives 12 and 14 were obtained, but 5 gave exclusively the β- d -(1→4) compound
摘要1,2:3,4-二-O-异亚丙基-α-d-吡喃半乳糖(6)及其6-三甲基甲硅烷基醚7与2,3,4,6-四-O-乙酰基-的糖基化在路易斯酸(例如四氟化钛)的存在下,以温和而快速的方式立体定向地获得了β-d-吡喃葡萄糖基氟(5),得到了β-(1→6)连接的二糖衍生物1。 2,3,4,6-四-O-苄基-β-d-吡喃葡萄糖基氟(8)或其α异构体10和四氟化钛在乙腈中的含量为6或7,快速反应优先进行,从而产生1,2:3 ,4-二-O-异亚丙基6-O-(2,3,4,6-四-O-苄基-β-d-吡喃葡萄糖基)-α-d-吡喃半乳糖(2)。然而,在醚中,主要形成α-(1→6)异构体。这些模型系统用于阐明该过程的限制条件,并讨论了机械概念。通过1,6-:2,3-双脱水-β-d-甘露吡喃糖(11)在O-4处的糖基化与过苄基的氟化物10一起合成α-和β-d-(1→4)二糖衍生物12得到14和16,但是5仅得到β