Synthesis of the 6-C-Methyl and 6-C-(Hydroxymethyl) Analogues ofN-Acetylneuraminic Acid and ofN-Acetyl-2,3-didehydro-2-deoxyneuraminic Acid
作者:Andrea Vasella、Ren� Wyler
DOI:10.1002/hlca.19900730620
日期:1990.9.19
(Scheme 3). The structure of 32 was established by X-ray analysis. Oxydation of 19 and 21, followed by deprotection, esterification, and acetylation gave 37 and 38, respectively (Scheme 4). The branched-chain Neu2en5Ac derivatives 4 and 5 were obtained by β-elimination ( 39 and 40) and deprotection. Omission of the esterification after oxydation of 33 and 34 gave the lactones 35 and 36 which were transformed
6-合成Ç甲基Neu2en5Ac(4),6-C-(羟甲基)-Neu2en5Ac(5),和6- Ç甲基的Neu5Ac(6)进行说明。还制备了4-甲基伞形铁基糖苷8和9,但证明不稳定。保护先前报道的硝基醚10(11),然后进行Kornblum反应,得到的支链衍生物13转化为醛14,因此通过16转化为受保护的6- C-羟甲基化20和6-C-甲基取代的18(方案1)。20和18的脱苄基作用分别得到二醇21和19。选择性氧化19,然后进行酯化(22),乙酰化(23)和消除反应,得到保护的6 - C-甲基-Neu2en5Ac衍生物24(流程2)。溴甲氧基化主要产生25和大约26,它们分别被还原脱溴为27和28。试图解除保护27没有产生相应的酸,但是导致了2,7-和2,8-脱水化合物29和30,其特征是它们的过乙酰化酯31和32(流程3)。通过X射线分析确定了32的结构。19和21的氧化,然后脱保护,酯