Han Hyun Ji, Park Suh Youn, Jeon So Eun, Kwak Jae Seok, Lee Ji Hye, Jaladi Ashok Kumar, Hwang Hyonseok, An Duk Keun
Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Republic of Korea.
Molecules. 2023 Oct 14;28(20):7090. doi: 10.3390/molecules28207090.
The reduction in esters, nitriles, and imines requires harsh conditions (highly reactive reagents, high temperatures, and pressures) or complex metal-ligand catalytic systems. Catalysts comprising earth-abundant and less toxic elements are desirable from the perspective of green chemistry. In this study, we developed a green hydroboration protocol for the reduction in esters, nitriles, and imines at room temperature (25 °C) using pinacolborane as the reducing agent and a commercially available Grignard reagent as the catalyst. Screening of various alkyl magnesium halides revealed MeMgCl as the optimal catalyst for the reduction. The hydroboration and subsequent hydrolysis of various esters yielded corresponding alcohols over a short reaction time (~0.5 h). The hydroboration of nitriles and imines produced various primary and secondary amines in excellent yields. Chemoselective reduction and density functional theory calculations are also performed. The proposed green hydroboration protocol eliminates the requirements for complex ligand systems and elevated temperatures, providing an effective method for the reduction in esters, nitriles, and imines at room temperature.
酯、腈和亚胺的还原需要苛刻的条件（高活性试剂、高温和高压）或复杂的金属-配体催化体系。从绿色化学的角度来看，含有储量丰富且毒性较小元素的催化剂是理想的。在本研究中，我们开发了一种绿色硼氢化方法，在室温（25℃）下使用频哪醇硼烷作为还原剂，市售格氏试剂作为催化剂，用于酯、腈和亚胺的还原。对各种烷基卤化镁的筛选表明，MeMgCl是还原反应的最佳催化剂。各种酯的硼氢化反应及随后的水解反应在较短的反应时间（约0.5小时）内生成了相应的醇。腈和亚胺的硼氢化反应以优异的产率生成了各种伯胺和仲胺。还进行了化学选择性还原和密度泛函理论计算。所提出的绿色硼氢化方法消除了对复杂配体体系和高温的需求，为室温下酯、腈和亚胺的还原提供了一种有效方法。
