Systematic variation of bidentate ligands used in aryl halide amination. Unexpected effects of steric, electronic, and geometric perturbations
Systematic variation of bidentate ligands used in aryl halide amination. Unexpected effects of steric, electronic, and geometric perturbations
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DOI：
10.1021/ja9721881
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发表时间：
1998-04-22
影响因子：
15
通讯作者：
Hartwig, JF
中科院分区：
文献类型：
--
作者：
Hamann, BC;Hartwig, JF
本文介绍了不同的二齿膦空间性质、电子性质和咬角对芳基溴胺化反应中产物比例的影响。胺产物与脱卤化氢产物的比率的比较表明，含有富电子、适度受阻膦且具有小咬角（接近90度）的催化剂具有最佳选择性。令人惊奇的是，由在N-H位氘化或在N-H位氘化或在氮上氘化的烷基胺的反应形成的芳烃副产物在许多实施例中显示出低水平的氘掺入。空间性质和配体咬角对伯胺单芳基化与二芳基化的选择性影响最大：具有小咬角的配体提供更高的单芳基化与二芳基化比率，空间体积增大的配体也是如此。贫电子或位阻二齿膦减少了富电子的钯键合芳烃与膦配体上的芳基交换所产生的产物的量。
This paper presents effects of varying bidentate phosphine steric properties, electronic properties, and bite angle on product ratios in the amination of aryl bromides. Comparisons of the ratios of amine products to dehydrohalogenation products showed that catalysts containing electron rich, modestly hindered phosphines with small bite angles (similar to 90 degrees) gave the best selectivities. Surprisingly, the arene side product formed from reaction of alkylamines deuterated in the N-H position or deuterated in the position or to the nitrogen showed low levels of deuterium incorporation in many examples. Steric properties and ligand bite angle had the greatest impact on the selectivity for monoarylation versus diarylation of primary amines: ligands with small bite angles gave higher monoarylation-to-diarylation ratios, as did ligands with increased steric bulk. Electron poor or sterically hindered bidentate phosphines reduced the amount of product resulting from aryl exchange of electron rich palladium-bound arenes with those of aryl groups on the phosphine ligands.