Sil Swagata, Santha Bhaskaran Athul, Chakraborty Soumi, Singh Bhagat, Kuniyil Rositha, Mandal Swadhin K
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India.
Department of Chemistry, Indian Institute of Technology, Palakkad 678557, Kerala, India.
J Am Chem Soc. 2022 Dec 14;144(49):22611-22621. doi: 10.1021/jacs.2c09225. Epub 2022 Nov 30.
We demonstrate that an in situ generated di-reduced phenalenyl (PLY) species accumulates sufficiently high energy and acts as a super electron donor to generate aryl radicals from aryl halides to accomplish Buchwald-Hartwig-type C-N cross-coupling reactions at room temperature. This catalytic protocol does not require any external stimuli such as heat, light, or cathodic current. This protocol shows a wide variety of substrate scope covering different genres of aryl and heteroaryl halides with various aromatic as well as aliphatic amines and late-stage functionalization of the well-known natural products. The control experiments, along with extensive density functional theory (DFT) calculations, unveil that the aryl radical is generated by a single electron transfer from the di-reduced PLY to the aryl halide substrate. The aryl radical acts as an electrophile and binds with amine, leading to the chemically driven radical-mediated C-N cross-coupling under transition-metal-free conditions.
我们证明,原位生成的二氢苊烯基(PLY)物种积累了足够高的能量,并作为超电子供体从芳基卤化物中生成芳基自由基,从而在室温下完成布赫瓦尔德-哈特维希型C-N交叉偶联反应。该催化方案不需要任何外部刺激,如热、光或阴极电流。该方案显示了广泛的底物范围,涵盖了不同类型的芳基和杂芳基卤化物以及各种芳香族和脂肪族胺,以及著名天然产物的后期官能团化。对照实验以及广泛的密度泛函理论(DFT)计算表明,芳基自由基是通过二氢PLY向芳基卤化物底物的单电子转移生成的。芳基自由基作为亲电试剂与胺结合,从而在无过渡金属条件下实现化学驱动的自由基介导的C-N交叉偶联。