SYNTHESIS OF 6-AMINO-6-DEOXY-2,3,4,5- TETRA-O-METHYL-D-GALACTONIC ACID, A KEY PRECURSOR OF A STEREOREGULAR POLYAMIDE1
作者:Carmen Zaliz、Oscar Varela
DOI:10.1081/car-100108283
日期:——
α-pyranoside (6). Methylation of the free hydroxyl groups of 5 and 6 gave the respective per-O-methyl derivatives 7 and 8. In order to maintain the size of the sugar ring during the sequence, compound 8 was alternatively prepared from 9, by acetylation, substitution by azide and per-O-methylation. Hydrolysis of the glycoside followed by oxidation and further 5-O-methylation afforded the 6-azido-6-deoxy carboxylic
标题化合物(17)是通过两个替代序列合成的,从D-半乳糖二丙酮化物(1)和甲基6 - O-甲苯磺酰基-α- D-吡喃半乳糖苷(9)开始。化合物1被转化为6-溴-6-脱氧衍生物2或被甲磺化为3。用叠氮化钠对2和3中的离去基团进行亲核取代,生成6-叠氮基6-脱氧衍生物4,在酸性条件下用甲醇处理后,得到相应的甲基β-呋喃糖苷(5)和α-吡喃糖苷(6)。的游离羟基基团的甲基化5和6,得到相应的per- ø -甲基衍生物7和8。为了在序列中维持糖环的大小,可替代地由9通过乙酰化,叠氮化物取代和过-O-甲基化制备化合物8。糖苷水解,然后氧化并进一步5- O-甲基化,得到6-叠氮基-6-脱氧羧酸16,其通过叠氮化物官能团的氢解转化为17(从9得到的总产率为38%)。