Kovác P
NIDDK, National Institutes of Health, Bethesda, Maryland 20892.
Carbohydr Res. 1993 Jul 19;245(2):219-31. doi: 10.1016/0008-6215(93)80073-n.
Methyl O-(2,4-di-O-benzoyl-3-O-bromoacetyl-alpha-L-rhamnopyranosyl)-(1-->3)- 2,4-di-O-benzoyl-alpha-L-rhamnopyranoside was treated with dichloromethyl methyl ether and ZnCl2 to give O-(2,4-di-O-benzoyl-3-O-bromoacetyl-alpha-L-rhamnopyranosyl)-(1-->3)2,4- di-O- benzoyl-alpha-L-rhamnopyranosyl chloride. Similar treatment of methyl O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D- glucopyranosyl)-(1-->3)-2,4-di-O-benzoyl-alpha-L-rhamnopyranoside (13) gave crystalline O-(3,4,6-tir-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl)-(1-- >3)-2,4-di-O- benzoyl-alpha-L-rhamnopyranosyl chloride (14), which was also obtained by treatment of methyl O-(3,4,6-tri-O-acetyl-2-azido-2-deoxo-alpha-D- glucopyranosyl)-(1-->3)-2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyranoside (12) with chlorine. In contrast to the conversion 12-->14, which was stereospecific, the reaction of methyl O-(3,4,6-tri-O-acetyl-2-azido-2- deoxy-alpha-D-glucopyranosyl)-(1-->3)-(O-2,4-di-O-benzoyl-alpha-L- rhamnopyranosyl)-(1-->3)-2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyrano sid e with chlorine gave a mixture of the corresponding alpha- (16) and beta- (17) glycosyl chlorides. Condensation of the mixed chlorides 16 and 17 with 1,3,4,6-tetra-O-acetyl-alpha-D-galactopyranose, followed by reduction-acetylation of the product, gave a fully protected derivative of the tetrasaccharide alpha-D-Glc pNAc-(1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2) -alpha-D-Galp.
O-（2,4-二-O-苯甲酰基-3-O-溴乙酰基-α-L-鼠李吡喃糖基）-（1→3）-2,4-二-O-苯甲酰基-α-L-鼠李吡喃糖苷用二氯甲基甲醚和氯化锌处理，得到O-（2,4-二-O-苯甲酰基-3-O-溴乙酰基-α-L-鼠李吡喃糖基）-（1→3）-2,4-二-O-苯甲酰基-α-L-鼠李吡喃糖基氯。O-（3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃葡萄糖基）-（1→3）-2,4-二-O-苯甲酰基-α-L-鼠李吡喃糖苷（13）进行类似处理，得到结晶状的O-（3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃葡萄糖基）-（1→3）-2,4-二-O-苯甲酰基-α-L-鼠李吡喃糖基氯（14），它也可通过用氯处理O-（3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃葡萄糖基）-（1→3）-2,4-二-O-苯甲酰基-1-硫代-α-L-鼠李吡喃糖苷（12）得到。与立体专一性的12→14转化不同，O-（3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃葡萄糖基）-（1→3）-（O-2,4-二-O-苯甲酰基-α-L-鼠李吡喃糖基）-（1→3）-2,4-二-O-苯甲酰基-1-硫代-α-L-鼠李吡喃糖苷与氯反应得到相应的α-（16）和β-（17）糖基氯的混合物。混合氯化物16和17与1,3,4,6-四-O-乙酰基-α-D-吡喃半乳糖缩合，然后对产物进行还原乙酰化，得到四糖α-D-Glc pNAc-（1→3）-α-L-Rhap-（1→3）-α-L-Rhap-（1→2）-α-D-Galp的全保护衍生物。
