A Highly Active Phosphine–Borane Organocatalyst for the Reduction of CO2 to Methanol Using Hydroboranes

• Published in: Journal of the American Chemical Society Vol. 135; no. 25; pp. 9326 - 9329
• Main Authors: Courtemanche, Marc-André, Légaré, Marc-André, Maron, Laurent, Fontaine, Frédéric-Georges
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 26.06.2013; Amer Chemical Soc
• Subjects: Boranes - chemistry; Carbon Dioxide - chemistry; Catalysis; Chemistry; Chemistry, Multidisciplinary; Methanol - chemical synthesis; Methanol - chemistry; Molecular Structure; Oxidation-Reduction; Phosphines - chemistry; Physical Sciences; Science & Technology; HOMOGENEOUS HYDROGENATION; CONVERSION; HYDROSILYLATION; FRUSTRATED LEWIS PAIRS; CATALYST; CARBON-DIOXIDE; FIXATION
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja404585p

In this work, we report that organocatalyst 1-Bcat-2-PPh2–C6H4 ((1); cat = catechol) acts as an ambiphilic metal-free system for the reduction of carbon dioxide in presence of hydroboranes (HBR2 = HBcat (catecholborane), HBpin (pinacolborane), 9-BBN (9-borabicyclo[3.3.1]­nonane), BH3·SMe2 and BH3·THF) to generate CH3OBR2 or (CH3OBO)3, products that can be readily hydrolyzed to methanol. The yields can be as high as 99% with exclusive formation of CH3OBR2 or (CH3OBO)3 with TON (turnover numbers) and TOF (turnover frequencies) reaching >2950 and 853 h–1, respectively. Furthermore, the catalyst exhibits “living” behavior: once the first loading is consumed, it resumes its activity on adding another loading of reagents.