Purposeful regioselectivity control of the Birch reductive alkylation of biphenyl-4-carbonitrile
Purposeful regioselectivity control of the Birch reductive alkylation of biphenyl-4-carbonitrile
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DOI：
10.1016/j.tet.2017.12.046
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发表时间：
2018-02-22
期刊：
影响因子：
2.1
通讯作者：
Shteingarts, Vitalij D.
中科院分区：
文献类型：
--
作者：
Fedyushin, Pavel A.;Peshkov, Roman Yu.;Shteingarts, Vitalij D.
Birch的联苯-4-腈（1）的还原烷基化提供了各种结构类型的烷基化1，4-二氢衍生物：4-烷基-4-苯基环己-2，5-二烯酮、1，4-二烷基-4-苯基环己-2，5-二烯腈（具有相同或不同的烷基片段）和4-（1-烷基环己-2，5-二烯基）苄腈。这些产物中的每一种都成为主要的，这取决于由1产生的长寿命阴离子形式的性质，即双电子还原的稳定产物-二价阴离子（1（2-））、1-烷基-4-氰基-1-苯基环己-2，5-二烯-4-基阴离子（1-Alk（1）（-）），其来源于二价阴离子1（2-）在联苯部分的1位上的烷基化;或1-（4-氰基苯基）环己-2，5-二烯-1-基阴离子（1-H-4，（-）），是二价阴离子1（2-）在4'位被质子化试剂（MeOH或NH 4Cl）质子化的产物。结合到联苯-4-甲腈支架的烷基片段的取向与计算的阴离子物种的电子结构的调查。它们对卤代烷的反应性主要是亲核的（S（N）2机理）。(C)2017爱思唯尔有限公司版权所有
Birch's reductive alkylation of biphenyl-4-carbonitrile (1) provides alkylated 1,4-dihydroderivatives of various structural types: 4-alkyl-4-phenylcyclohexa-2,5-dienone, 1,4-dialkyl-4-phenylcyclohexa-2,5-dienecarbonitrile (with the same or different alkyl fragments), and 4-(1-alkylcyclohexa-2,5-dienyl) benzonitrile. Each of these products become dominant depending on the nature of long-living anionic form generated from 1, namely, the stable product of two-electrons reduction - dianion (1(2-)); 1-alkyl-4-cyano-1-phenylcyclohexa-2,5-dien-4-yl anion (1-Alk(1)(-)), originated due to the alkylation of dianion 1(2-) at the position 1 of biphenyl moiety; or 1-(4-cyanophenyl)cyclohexa-2,5-dien-1-yl anion (1-H-4,(-)), being the product of dianion 1(2-) protonation at position 4' by protonating reagent (MeOH or NH4Cl). The orientation of alkyl fragment incorporation into biphenyl-4-carbonitrile scaffold is in agreement with calculated electronic structure of the anionic species under investigation. The dominating type of their reactivity towards alkyl halides proved to be nucleophilic (S(N)2 mechanism). (C) 2017 Elsevier Ltd. All rights reserved.