An Expeditious Route to<i>N</i>-Acetyl-D-galactosamine from<i>N</i>-Acetyl-D-glucosamine Based on the Selective Protection of Hydroxy Groups
作者:Naoyuki Ito、Yoshihide Tokuda、Shigeru Ohba、Takeshi Sugai
DOI:10.1246/bcsj.77.1181
日期:2004.6
GalNAc (1) was straightforwardly prepared from GlcNAc (2a) in six steps. Selective protection of the hydroxy groups on the C-1, C-3, and C-6 positions at the same time was performed by the treatment of TBDPS chloride (5.5 eq.) in DMF in 70% yield. The nucleophilic attack with CsOAc or KOBz on the chloromethylsulfonyloxy group at C-4 worked well (69–77% yield), accompanied by an unexpected rearrangement, to give the furanose products (6). The deprotection of all silyl and acyl groups under acidic conditions and the re-acetylation provided GalNAc (1) in 51% yield.
GalNAc (1) 通过六个步骤从 GlcNAc (2a) 直接合成。采用 TBDPS 氯化物(5.5 eq.)在 DMF 中进行选择性保护 C-1、C-3 和 C-6 位的羟基,反应产率为 70%。使用 CsOAc 或 KOBz 对 C-4 位的氯甲基磺酰氧基进行亲核攻击效果良好(产率为 69-77%),并伴随意外的重排,形成呋喃糖产品 (6)。在酸性条件下去保护所有的硅基和酰基,随后再乙酰化,得到 GalNAc (1),产率为 51%。