Center of Bio-Medical Research, Division of Molecular Synthesis & Drug Discovery, SGPGIMS Campus, Raebareli Road, Lucknow, 226014 Uttar Pradesh, India.
J Am Chem Soc. 2021 Apr 7;143(13):5022-5037. doi: 10.1021/jacs.0c13415. Epub 2021 Mar 30.
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and -selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp)-H and C(sp)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
在这里，我们描述了一类新的 C-H 硼化催化剂的发现及其在芳基、杂芳基和脂肪族体系的区域选择性 C-H 硼化中的应用。新的催化剂具有 Ir-C(噻吩基)或 Ir-C(呋喃基)阴离子配体，而不是标准 C-H 硼化条件中使用的二胺型中性螯合配体。据报道，这些新发现的催化剂在具有高分离产率的各种芳基底物的反应中表现出优异的反应性和区域选择性。此外，这些催化剂还被证明对大量脂肪族底物的选择性 C(sp)-H 键硼化具有高效性。杂环分子通过 C-H 键固有的高反应性选择性进行硼化。使用相同的催化剂描述了许多晚期 C-H 官能化反应。此外，我们表明，即使在开放空气中也可以使用其中一种催化剂进行 C(sp)-H 和 C(sp)-H 硼化，从而使该方法更加通用。初步的机理研究表明，活性催化中间体是 Ir(双)硼基配合物，而连接的配体充当双齿配体。总的来说，这项研究强调了一类新的 C-H 硼化催化剂的发现，它们应该在 C-H 官能化化学的背景下得到广泛应用。
