Intramolecular Insertion of Alkenes into Pd-N Bonds. Effects of Substrate and Ligand Structure on the Reactivity of (P-P)Pd(Ar)[N(Ar1)(CH2)3CR=CHR′] Complexes
Intramolecular Insertion of Alkenes into Pd-N Bonds. Effects of Substrate and Ligand Structure on the Reactivity of (P-P)Pd(Ar)[N(Ar1)(CH2)3CR=CHR′] Complexes
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DOI：
10.1021/om200008t
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发表时间：
2011-03-14
期刊：
影响因子：
2.8
通讯作者：
Wolfe, John P.
中科院分区：
文献类型：
--
作者：
Neukom, Joshua D.;Perch, Nicholas S.;Wolfe, John P.
报道了一系列(P-P)Pd(Ar)[N(Ari)(CH2)(3)Cr=Cr‘]配合物3的合成和反应活性。通过将侧链烯烃插入Pd-N键，这些配合物转变为可观察到的(P-P)Pd(Ar)[吡咯烷基-2-甲基]配合物4。配合物4经C-C成键还原消除反应生成N-芳基-2-苄基吡咯烷衍生物2。动力学研究表明，3到4和4到2的转化率均在1个数量级以内。报道了膦配体结构、烯烃取代、Ar和Ar-1基团的电子性质对反应速率的影响，以及氚同位素效应的研究结果。详细讨论了氨基拆分的反应机理，实验结果与通过速率决定的配体置换和快速氨基拆分将3转化为4的结果最为一致。这些转化是未活化的烯烃向Pd-N键的同步迁移插入的罕见例子。
Studies on the synthesis and reactivity of a series of (P-P)Pd(Ar)[N(Ari)(CH2)(3)CR=CHR'] complexes 3 are described. These complexes are transformed to observable (P P)Pd(Ar)[pyrrolidin-2-ylmethyl] complexes 4 via syn insertion of the pendant alkene into the Pd N bond. Complexes 4 then undergo C C bond-forming reductive elimination to yield N-aryl-2-benzylpyrrolidine derivatives 2. Kinetic studies indicate the rates of conversion of 3 to 4 and 4 to 2 are within I order of magnitude. The effects of phosphine ligand structure, alkene substitution, and the electronic properties of the Ar and Ar-1 groups on reaction rates are reported, as are the results of deuterium isotope effect studies. The mechanism of the aminopalladation step is discussed in detail, and the results of the experiments described in this paper are most consistent with conversion of 3 to 4 via rate-determining ligand displacement followed by fast aminopalladation. These transformations represent rare examples of syn migratory insertion of unactivated alkenes into Pd N bonds.