Abstract Kinetically controlled reaction of 4.5 equiv. of 2-methoxypropene with some alkyl α- and β- d -galactopyranosides gave the 2,3:4,6-di- O -isopropylidene derivatives in high yields (80–85%). With 2 equiv. of 2-methoxypropene, benzyl β- d -galactopyranoside gave the 4,6- and the 3,4-monoacetals in the ratio 30:1 together with ∼20% of the 2,3:4,6-diacetal. The structures of methyl 2,3:4,6-di-
摘要4.5当量的动力学控制反应。用
2-甲氧基丙烯与一些烷基α-和β-d-
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乳糖苷合成高产率(80-85%)的2,3:4,6-二-O-异亚丙基衍
生物。拥有2个当量 用
2-甲氧基丙烯,苄基β-d-
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乳糖苷以30∶1的比例得到4,6-和3,4-单
缩醛,以及〜20%的2,3:4,6-二
缩醛。通过X射线分析确定甲基2,3:4,6-二-O-异亚丙基-α-和-β-d-
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乳糖苷的结构。前者在斜方晶系P 2 1 2 1 2 1中结晶,a = 5.503,b = 16.105,c = 16.822 A,Z = 4,后者在单斜晶系P 2 1中,a = 10.400 ,b = 13.344,c = 11.647 A,β= 111.50,Z =4。α端基异构体和两个β端基异构体分子具有d-
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乳糖苷和1,扭曲椅构型中的3-二氧杂
环戊烷环和半椅构型中的二
氧戊环环。Nmr光谱表明溶液中存在相似的构象。