Glycosylidene Carbenes. Part 10. Regioselective Glycosidation of 4,6-<i>O</i>-Benzylidene-<scp>D</scp>-altropyranosides
作者:Eva Bozó、Andrea Vasella
DOI:10.1002/hlca.19920750816
日期:1992.12.16
Glycosidation by the diazirine 1, the trichloroacetimidate 4, and the bromide 5 of the altro-diol 2, possessing an intramolecular H-bond (HOC(3) to OC(1)) in solution, but not in the solid state, proceeds with high and complementary regioselectivity. From 2 and 1, one obtains mostly the 1,2-linked disaccharides 10 and 11 (β-D > α-D), together with the 1,3-linked isomers 12 and 13 (α-D > β-D; 1,2-/1
由二吖丙因苷1中,三氯乙4,和溴化物5所述的雅卓二醇2,具有分子内氢键(HOC(3)OC(1))在溶液中,而不是在固体状态,继续进行高和互补的区域选择性。从2和1中,一个人主要获得1,2连接的二糖10和11(β-D>α-D),以及1,3连接的异构体12和13(α-D>β-D; 1 ,2- / 1,3-连接的产物,大约9:1),去甲基的1,3-连接的二糖24–27,三糖19–22,内酯the嗪23和羟基葡糖醛18,而2与4或5反应,主要生成1,3-连接的二糖(1,2- / 1,3-连接的产物,约1:9)。二糖还被表征为乙酸盐(14–17,28–31)。产率和立体选择性取决于给体,化学计量,溶剂,温度和浓度。1,3联二糖的糖基化与1产生三糖19-22。β-D- α-二醇3与1的反应以1:1的比例得到1,2-和1,3-连接的二糖32/33和34/35,表征为乙酸酯36-39,而根据Lemieux用5进行糖基化进行区域选择性(1