反体二氯菊酸的立体选择合成

Stereoselective Synthesis of trans-2,2-Dimethyl3-(2,2-dichloroethenyl) cyclopropanecarboxlic acid

以贲亭酸甲酯为原料,经自由基加成、立体有择环化合成了富反式二氯菊酸甲酯,收率高达95%,反顺比为88∶12。还以顺反混合体 (trans/cis=60/40) 二氯菊酸酰氯为原料,立体选择性转化合成富反式二氯菊酸酯,对催化剂、反应时间、溶剂进行条件实验,以4-二甲氨基吡啶催化立体转化效果最好,收率95%,反顺比达93/7。

Methyl 3,3-dimethyl-4,6,6,6-tetrachlorohexanoate, which was obtained by addition of carbon tetrachloride to methyl 3,3-dimethyl-4-pentenoate, was treated with sodium methoxide in a single-vessel via methyl 4,6,6-trichloro-3,3- dimethyl-5-hexenoate to give trans-rich methyl, 2,2-dimethyl-3- (2,2-dichloroethenyl) cyclopropanecarboxy-late in 95% yield. Trans-2,2-dimethyl-3-(2,2-dichloroethenyl)cyclopropanecarbonyl chloride was obtained by isomerization of the cis/trans mixture with 4-(N,N-dimethylamino) pyridine in 95% yield.