Origin of the Difference in Reactivity between Ir Catalysts for the Borylation of C-H Bonds,Journal of the American Chemical Society

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Origin of the Difference in Reactivity between Ir Catalysts for the Borylation of C-H Bonds
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-09-20 , DOI: 10.1021/jacs.9b08920
Raphael J Oeschger ₁ , Matthew A Larsen ₁ , Alessandro Bismuto ₁ , John F Hartwig ₁

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A mechanistic study on the origin of the difference in reactivity between Ir catalysts for C-H borylation reactions is reported. Catalytic reactions of B2pin2 with a series of substrates that require high temperatures and long reaction times were conduct-ed. Reactions catalyzed by the combination of [Ir(COD)(OMe)]2 and 3,4,7,8-tetramethylphenanthroline (tmphen) occur in yields that are substantially higher yields than those of reactions catalyzed by [Ir(COD)(OMe)]2 and 4,4'-di-tert-butylbipyridine (dtbpy). The electronic properties of Ir catalysts ligated by dtbpy or tmphen and their stoichiometric reactivi-ty were investigated. It was found that the longer lifetime, rather than higher reactivity of the catalyst, leads to higher yields of reactions catalyzed by Ir-tmphen. The catalyst ligated by dtbpy decomposes principally by dissociation of the ligand and rapid borylation at the positions alpha to nitrogen. Thus, the greater stability of the catalyst containing tmphen results from its greater binding constant.

中文翻译：

Ir 催化剂对 CH 键的硼化反应活性差异的原因

报道了 Ir 催化剂在 CH 硼化反应中反应性差异的机理研究。进行了B2pin2与一系列需要高温和长反应时间的底物的催化反应。由 [Ir(COD)(OMe)]2 和 3,4,7,8-四甲基菲咯啉 (tmphen) 组合催化的反应的产率明显高于由 [Ir(COD)(OMe) 催化的反应的产率)]2 和 4,4'-二叔丁基联吡啶 (dtbpy)。研究了 dtbpy 或 tmphen 连接的 Ir 催化剂的电子性质及其化学计量反应性。发现更长的寿命，而不是更高的催化剂反应性，导致由 Ir-tmphen 催化的反应产率更高。由 dtbpy 连接的催化剂主要通过配体的解离和在氮的 α 位上的快速硼化来分解。因此，含有tmphen的催化剂的更大稳定性是由于其更大的结合常数。

更新日期：2019-09-20

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