Isopropylidenation of lactose with 2,2-dimethoxypropane in N , N -dimethyl-formamide at 80-85° gave a 1:2 mixture of the kinetically favored 4′,6′-acetal 1 and the thermodynamically more-stable 3′,4′-acetal 2 , which were separated by chromatography. The 1,2,3,6,2′,6′-hexaacetate ( 3 ) and the 1,2,3,6,2′,6′-hexabenzoate ( 4 ) of 2 , as well as the corresponding, deacetonated esters 5 and 6 , were prepared by standard
摘要
乳糖与
2,2-二甲氧基丙烷在N,N-二甲基-甲酰胺中于80-85°进行异丙基异丙基化反应,得到动力学上有利的4',6'-
乙缩醛1和热力学上更稳定的3'的1:2混合物, 4'-
乙缩醛2,通过色谱法分离。1,2,3,6,2',6'-六
乙酸酯(3)和1,2,3,6,2',6'-六
苯甲酸酯(4)以及相应的脱
丙酮酯图5和图6是通过标准程序制备的。1,2,3,6,2',6'-六-O-乙酰基-α,
β-乳糖(5)与2,3,4三-O-苯甲酰基-1-
呋喃核糖基
溴的缩合反应
溴离子催化得到α-(1''→3')-连接的被保护的三糖8。脱乙酰基,然后氢解除去苄基,得到标题三糖10。六
乙酸酯5也与2,3,4-三-O-乙酰基-α-1-
呋喃核糖基
溴化物缩合,