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3-甲氧基-4,5-次甲二氧基苯甲酸甲酯(1)是合成联苯双酯(Ⅱ,4,4′-二甲氧基-5,6,5′,6′-二次甲二氧基-2,2′一二甲羰基联苯)的主要中间体。联苯双酯是我国独创的具有降酶幅度大、速度快、副作用小、药理作用较强的人工合成治疗肝炎的新型药物。曾报道用二碘甲烷合成(Ⅰ)。近期又报道采用相转移催化合成(Ⅰ),其中用二溴甲烷收率为75～80%,用二氯甲烷收率为20%~2。我们在二氯甲烷制备二碘甲烷方法~(34)启发下,用二氯甲烷代替二碘甲烷,用碘化钾作催化剂合成(Ⅰ),取得了成功,收率可达50%,此法可大幅度降低生产成本,反应式如下:
Methyl 3-methoxy-4,5-dimethoxybenzoate (1) is a synthetic bifendate (II, 4,4’-dimethoxy-5,6,5 ’, 6’ - Dimethyldioxy-2,2 ’- a carbonyl carbonyl biphenyl) the main intermediates. Biphenyl Diester is a new type of synthetic medicine for Hepatitis, which is unique in our country and has the advantages of large magnitude of reducing enzyme, high speed, little side effect and strong pharmacological action. Synthesis of methyl iodide has been reported (I). It has also recently been reported that phase transfer catalysis (I) was used with a yield of 75-80% for dibromomethane and a yield of 20% -2 for methylene chloride. We have succeeded in dichloromethane (I) by the method of dichloromethane (34), methylene chloride instead of methylene iodide and potassium iodide as catalyst (Ⅰ). The yield is up to 50% Amplitude lower production costs, the reaction is as follows: