2-巯基-5-甲氧基咪唑并［4,5-b］吡啶的合成工艺

对新型质子泵抑制剂泰妥拉唑的关键中间体2-巯基-5-甲氧基咪唑并4,5-b]吡啶的合成工艺进行了研究，以2,6-二氯吡啶为原料，先硝化得到2,6-二氯-3-硝基吡啶，然后经胺化得2-氨基-3-硝基-6-氯吡啶，再与甲醇钠反应得2-氨基-3-硝基-6-甲氧基吡啶，用铁粉还原得2,3-二氨基-6-甲氧基吡啶，最后与二硫化碳环化制得标题化合物。各步反应的最佳反应条件(反应温度，反应时间，摩尔收率)分别为，硝化： 110℃, 8 h, 79.3％; 胺化：室温, 10 h, 87.6％; 甲氧基化：65℃, 30min, 98.7％; 还原：回流, 3hrs; 环化：回流, 4hrs, 71.3％(还原及环化两步)。 标题化合物熔点与文献报道一致，并通过1H NMR进一步确证结构。

Synthesis of 2-mercapto-5-methoxyimidazo[4,5-b] pyridine

The synthesis process of 2-mercapto-5-methoxyimidazo［4,5-b］pyridine, a crucial intermediate of tenatoprazole which is a new proton pump inhibitor, was studied.2,6-Dichloropyridine as raw material was nitrated by nitric acid/sulfuric acid, and after amination 2-amino-3-nitro-6-chloropyridine was obtained.It then reacted with sodium methoxide to give 2-amino-3-nitro-6-methoxypyridine and the intermediate was reduced by H2 with Raney Ni as catalyst to give 2,3-diamino-6-methoxypyridine.Finally cyclization was finished with carbon bisulfide to give the title compound.The optimal reaction conditions and yield(temperature, time, molar yield) were as follows: nitration,110℃, 8 h, 79.3%; amination, room temperature, 10 h, 87.6%; methoxylation,65℃, 30min, 98.7%; reduction,70℃, 3 h; cyclization, reflux, 4 h, 72.4% (two steps).The melting point of the title compound was the same as that reported in literature, and its structure was confirmed by 1H NMR.