KINETICS AND MECHANISM OF THE C-ALKYLATION OF NITROALKANE ANIONS BY 1-ALKYL-2,4,6-TRIPHENYLPYRIDINIUMS - A NON-CHAIN REACTION WITH RADICALOID CHARACTERISTICS
KINETICS AND MECHANISM OF THE C-ALKYLATION OF NITROALKANE ANIONS BY 1-ALKYL-2,4,6-TRIPHENYLPYRIDINIUMS - A NON-CHAIN REACTION WITH RADICALOID CHARACTERISTICS
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DOI：
10.1021/ja00339a016
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发表时间：
1983-01-01
影响因子：
15
通讯作者：
PATEL, RC
中科院分区：
文献类型：
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作者：
KATRITZKY, AR;KASHMIRI, MA;PATEL, RC
2-硝基丙烷与N-取代吡啶鎓的C-烷基化反应在Me_2SO中均为一级反应。定量地研究了温度、N取代基、离去基团和亲核试剂的速率对反应的影响。总的来说，证据排除了SN 2置换，并表明反应通过自由基非链机制进行。我们已经表明2，N-（伯烷基）-、N-（仲烷基）-和N-苄基-2，4，6-三苯基吡啶鎓（1）与衍生自硝基甲烷、硝基乙烷和2-硝基丙烷的硝膦酸根阴离子2a-c的反应在可替代的有用反应中产生相应的C-烷基化硝基化合物6（方案I）。我们现在报告动力学研究2-硝基丙烷钠（2c）和硝基甲烷（2a）作为亲核试剂在Me 2SO溶液中，旨在澄清这些反应的机理。的工作。使用的吡啶鎓通过标准方法制备。图3反应物之间的一些制备反应
The C-alkylation of 2-nitropropanide by N-substituted pyridiniums is first order in each reactant in Me2SO. The effect on the rate of temperature, N substituent, leaving group, and nucleophile was studied quantitatively. Overall, the evidence excludes an SN2 displacement and suggests that the reactions proceed by a free radical nonchain mechanism.+ We haveshown2 that the reaction of^-(primary alkyl)-, N-(secondary alkyl)-, and TV-benzyl-2, 4, 6-triphenylpyridiniums (1) with nitronate anions 2a-c derived from nitromethane, nitroethane, and 2-nitropropane yields the corresponding C-alkylated nitro compounds 6 in preparatively useful reactions (Scheme I). We now report kinetic studies with sodium 2-nitropropanide (2c) and nitromethanide (2a) as nucleophiles in Me2SO solution designed to clarify the mechanisms of these reactions. Preparative Work. The pyridiniums used were prepared by standard methods. 3 Some preparative reactions between the