Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a gallium trichloride/tartrate system under neutral conditions.
Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a gallium trichloride/tartrate system under neutral conditions.
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DOI：
10.1039/b804589e
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发表时间：
2008-07
影响因子：
3.2
通讯作者：
M. Yasuda;K. Shimizu;S. Yamasaki;A. Baba
中科院分区：
文献类型：
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作者：
M. Yasuda;K. Shimizu;S. Yamasaki;A. Baba
仲醇1与氯二甲基硅烷（HSiMe(2)Cl）在一定催化量的GaCl(3)/酒石酸二乙酯存在下反应生成相应的有机氯化物3。在催化循环中，酒石酸二乙酯4a与HSiMe(2)Cl 2反应生成氯硅醚5，生成H(2)。形成的氯硅醚5和底物醇1之间的醇交换生成烷氧氯硅烷6，它与催化的GaCl(3)反应生成氯化产物3。GaCl(3)的刘易斯酸度适中，有利于氯化反应。强路易斯酸由于对氧官能团的亲和力过大而不能生成产物。虽然叔醇在没有酒石酸二乙酯的情况下也能被该体系氯化，但某些不太可能产生碳正离子的醇在使用GaCl(3)/酒石酸二乙酯体系时能被有效地氯化。
The reaction of secondary alcohols 1 with chlorodimethylsilane (HSiMe(2)Cl) proceeded in the presence of a catalytic amount of GaCl(3)/diethyl tartrate to give the corresponding organic chlorides 3. In the catalytic cycle, the reaction of diethyl tartrate 4a with HSiMe(2)Cl 2 gives the chlorosilyl ether 5 with generation of H(2). Alcohol-exchange between the formed chlorosilyl ether 5 and the substrate alcohol 1 affords alkoxychlorosilane 6, which reacts with catalytic GaCl(3) to give the chlorinated product 3. The moderate Lewis acidity of GaCl(3) facilitates chlorination. Strong Lewis acids did not give product due to excessive affinity for the oxy-functionalities. Although tertiary alcohols were chlorinated by this system even in the absence of diethyl tartrate, certain alcohols that are less likely to give carbocationic species were effectively chlorinated using the GaCl(3)/diethyl tartrate system.