Secondary deuterium kinetic isotope effects in irreversible additions of allyl reagents to benzaldehyde
Secondary deuterium kinetic isotope effects in irreversible additions of allyl reagents to benzaldehyde
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DOI：
10.1021/jo0164002
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发表时间：
2002-06-14
影响因子：
3.6
通讯作者：
Henderson, JL
中科院分区：
文献类型：
--
作者：
Gajewski, JJ;Bocian, W;Henderson, JL
四氢呋喃水溶液中烯丙基三丁基锡、二异丙基硼酸二丙基烯丙基以及烯丙基溴和锌粉对苯甲醛-h和-d的加成竞争动力学具有逆的二次氘动力学同位素效应（SDKIEs）。这些反向的sdky与烯丙基锂和烯丙基格氏获得的正常sdky相反，表明在这些情况下决定速率的单电子转移。通过各种MO计算，硼酸烯丙基加成的过渡态发生在大量的B-O键形成和很少的C-C键形成。与合理的平衡同位素效应相比，其他两种烯化试剂的SDKIEs的大小表明过渡态具有大量的C-C键形成。
The competitive kinetics of additions of allyl to benzaldehyde-h and -d from allyltributyl tin, from diisopropyltartrylallyl boronate, and from allyl bromide and zinc dust in aqueous tetrahydrofuran have inverse secondary deuterium kinetic isotope effects, SDKIEs. These inverse SDKIEs are in contrast to the normal SDKIEs that were obtained with allyl lithium and allyl Grignard, suggesting rate-determining single-electron transfer in these cases. By various MO calculations the transition state for addition of allyl boronate occurs with substantial B-O bond formation and little C-C bond formation. The magnitudes of the SDKIEs with the other two allylating reagents, when compared with reasonable equilibrium isotope effects for the addition, suggest transition states with substantial C-C bond formation.