Yu Isaac F, D'Angelo Kyan A, Hernandez-Mejías Ángel D, Cheng Nanrun, Hartwig John F
Department of Chemistry, University of California, Berkeley, California 94720, United States.
J Am Chem Soc. 2024 Mar 20;146(11):7124-7129. doi: 10.1021/jacs.3c12981. Epub 2024 Mar 8.
The catalytic, undirected borylation of alkyl C-H bonds typically occurs at high reaction temperatures or with excess substrate, or both, because of the low reactivity of alkyl C-H bonds. Here we report a new iridium system comprising 2-anilino-1,10-phenanthroline as the ligand that catalyzes the borylation of alkyl C-H bonds with little to no induction period and with high reaction rates. This superior activation and reactivity profile of 2-aminophenanthroline-ligated catalysts leads to broader reaction scope, including reactions of sensitive substrates, such as epoxides and glycosidic acetals, enhanced diastereoselectivity, and higher yields of borylated products. These catalysts also enable the borylation of alkanes, amines, and ethers at room temperature for the first time. Mechanistic studies imply that facile -borylation occurs under the reaction conditions and that iridium complexes containing -boryl aminophenanthrolines are competent precatalysts for the reaction.
由于烷基C-H键的低反应活性，烷基C-H键的催化、无导向硼化反应通常在高反应温度下或使用过量底物或两者兼而有之的情况下发生。在此，我们报道了一种以2-苯胺基-1,10-菲咯啉为配体的新型铱体系，该体系能催化烷基C-H键的硼化反应，几乎没有诱导期且反应速率很高。2-氨基菲咯啉配位催化剂这种卓越的活化和反应活性特征导致了更广泛的反应范围，包括敏感底物（如环氧化物和糖苷缩醛）的反应、增强的非对映选择性以及硼化产物的更高产率。这些催化剂还首次实现了在室温下对烷烃、胺和醚的硼化反应。机理研究表明，在反应条件下容易发生β-硼化反应，并且含有β-硼基氨基菲咯啉的铱配合物是该反应的有效预催化剂。
