Dondoni Alessandro, Zuurmond Helene M., Boscarato Alessia
Dipartimento di Chimica, Laboratorio di Chimica Organica, Università, 44100-Ferrara, Italy.
J Org Chem. 1997 Nov 14;62(23):8114-8124. doi: 10.1021/jo971177n.
The synthesis of (1-->6)-C-disaccharides by Wittig condensation of formyl C-glycofuranosides and pyranosides with galacto- and glucopyranose 6-phosphoranes is described herein. The method involves the coupling of the sugar aldehydes with the ylides and the reduction of the double bond of the resulting sugar alkenes, in most of the cases by catalytic hydrogenation. The reduction with nickel boride or diimide is employed in some special cases. O-Benzyl protective groups are removed by catalytic hydrogenation either in the course of the reduction of the double bond or in a subsequent step, while O-isopropylidene groups are cleaved by treatment with Amberlite IR-120. In this way, eight free beta-D-(1-->6)-C-disaccharides have been prepared in 26-61% overall yield starting from beta-linked formyl C-glycosides. These include C-linked analogues of the biologically active disaccharides allolactose (Galbeta1,6Glc), gentiobiose (Glcbeta1,6Glc), and N-acetylamino disaccharides (GalNHAcbeta1,6Gal and GalNHAcbeta1,6Glc). Moreover, the synthesis of two alpha-D-(1-->6)-C-disaccharides is described from formyl C-furanosides. The limiting condition of the synthesis of these stereoisomers is the configurational instability of the alpha-linked formyl C-glycosides under the basic conditions of the Wittig olefination.
本文描述了通过甲酰基 C - 呋喃糖苷和吡喃糖苷与半乳糖和葡萄糖吡喃糖 6 - 膦叶立德的维蒂希缩合反应合成(1→6)-C - 二糖的方法。该方法包括糖醛与叶立德的偶联以及所得糖烯烃双键的还原，在大多数情况下通过催化氢化进行。在一些特殊情况下采用硼化镍或二亚胺进行还原。O - 苄基保护基在双键还原过程中或后续步骤中通过催化氢化去除，而 O - 异亚丙基保护基用Amberlite IR - 120处理裂解。通过这种方式，从β - 连接的甲酰基 C - 糖苷开始，以 26% - 61%的总收率制备了八种游离的β - D-(1→6)-C - 二糖。这些包括生物活性二糖别乳糖（Galβ1,6Glc）、龙胆二糖（Glcβ1,6Glc）以及 N - 乙酰氨基二糖（GalNHAcβ1,6Gal 和 GalNHAcβ1,6Glc）的 C - 连接类似物。此外，还描述了从甲酰基 C - 呋喃糖苷合成两种α - D-(1→6)-C - 二糖的方法。这些立体异构体合成的限制条件是在维蒂希烯化反应的碱性条件下，α - 连接的甲酰基 C - 糖苷的构型不稳定性。
