De Novo Synthesis of a Methylene-Bridged Neu5Ac-α-(2,3)-Gal <i>C</i>-Disaccharide
作者:Wolfgang Notz、Christian Hartel、Bernhard Waldscheck、Richard R. Schmidt
DOI:10.1021/jo015543l
日期:2001.6.1
treatment with phenylselenyl triflate, was stereoselectively cyclized in a 6-exo-trig selective manner. A selena-Pummerer rearrangement, oxidation, and esterification readily led to methyl ester 37 which, after deacetylation, could be regioselectively tetrabenzoylated with benzoyl cyanide. Triflate activation of the axial hydroxyl group in 40 and nucleophilic displacement by azide ion with inversion
已开发出一种合成N-乙酰神经氨酸(Neu5Ac)的C-酮苷的一般策略,并将其成功地用于合成亚甲基桥接的Neu5Ac-α-(2,3)-Gal C-二糖2。这种新颖方法的一个元素是借助适当的开链前体4通过苯三氟乙烯苯磺酸酯的立体选择性,6-exo-trig选择性,亲电环化。通过将可从D-半乳糖获得的锂化的碘化物18添加到通过链延长从D-葡糖酸-δ-内酯获得的开链醛5a中来形成开链前体。随后使用Tebbe试剂将C1掺入,形成环状碳酸酯并对两个异亚丙基缩酮进行脱保护,从而得到季戊四醇4,将其用三氟甲磺酸苯硒基酯处理后,以6-exo-trig选择性方式立体选择性环化。selena-Pummerer重排,氧化和酯化反应容易产生甲酯37,在脱乙酰基作用后,可以用苯甲酰氰将其区域选择性地四苯甲酰化。三氟甲磺酸酯对40中轴向羟基的活化和叠氮化物离子的亲核取代以及构型的反转提供了叠氮化物41,叠氮化物41被氢