2-巯基-5-二氟甲氧基苯并咪唑合成新工艺

Novel Synthetic Process of 5-Difluoromethoxy-2-Mercapto-1H-Benzimidazole

以扑热息痛为原料,采用高压釜密闭条件下,研究压力、溶剂、催化剂和无机碱等对反应过程的影响,结果表明:当压力为0.5MPa,溶剂为异丙醇,催化剂为聚乙二醇400,无机碱为碳酸钾,4-二氟甲氧基乙酰苯胺收率可达71%;硝基化合物以w(Pd)=10%钯碳为催化剂,在压力=0.4 MPa下,加氢还原后直接与二硫化碳反应"一锅法"环合得到2-巯基-5-二氟甲氧基苯并咪唑,两步总收率为94%。

N-（4-difluoromethoxyphenyl）-acetamide was synthesized from paracetamol in the pressure-tight autoclave.The effects of pressure,solvent,catalyst and inorganic base were also studied.It is found that the yield can reach 71% with isopropanol as solvent,PEG-400 as catalyst,and potassium carbonate as base under the pressure of 0.5MPa.Nitro-compound is reduced by hydrogen with the catalyst of w（Pd）=10% palladium carbon under the pressure of 0.4MPa.The resulted solution is then reacted directly with carbon disulfide to obtain 5-difluoromethoxy-2-mercapto-1H-benzimidazole via one-pot cyclization.The total yield of two steps is 94%.