Alkylation of alkenes:: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
Alkylation of alkenes:: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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DOI：
10.1021/ja048904y
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发表时间：
2004-08-25
影响因子：
15
通讯作者：
Metzger, JO
中科院分区：
文献类型：
--
作者：
Biermann, U;Metzger, JO
本文研究了在乙基铝倍半氧化物（Et 3Al 2Cl 3）的作用下，氯甲酸烷基酯（伯、仲）和焦碳酸二叔丁酯（52）与烯烃的非活性C=C双键进行烃基加成反应的一般方法。1,2和52分别与Et 3Al 2Cl 3反应得到烷基阳离子，该烷基阳离子被加成到烯烃上;氢化物转移到加合碳负离子上，或者如果适用的话，1，2-H位移，然后氢化物从Et 3Al 2Cl 3转移到重排的加合碳负离子上，得到饱和加成产物。该反应已被应用于1-烯烃，2-甲基-1-烯烃，内双键，和三个环烯烃。特别关注的是不饱和脂肪化合物的烷基化，例如油酸（2），它们是重要的可再生原料。2-甲基烷烃、3-甲基烷烃、2，4-二甲基烷烃、2，3-二甲基烷烃、2，2，4-三甲基烷烃、环己基烷烃以及具有相应支链烷基链的羧酸和酯已经以良好至中等产率合成。
A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbeniurn ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbeniurn ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.