A metal-free catalyst born of frustration: Boron (a Lewis acid) and nitrogen or phosphorus fragments (both Lewis bases) tend to pair up. Keeping them separated on opposite ends of the same molecule creates a “frustrated” Lewis pair. Such molecules can manifest powerful reactivity, such as scission of the hydrogen-hydrogen bond in H ₂ . Légaré et al. now extend this reactivity to the cleavage of carbon-hydrogen bonds in heteroaromatic compounds such as furans and pyrroles (see the Perspective by Bose and Marder). Their frustrated Lewis pair complex catalyzed borylation of these compounds. The selectivity pattern of the reaction complemented that seen with the metal catalysts conventionally used. Science , this issue p. 513 ; see also p. 473

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.

The FLP species 1-BR₂-2-NMe₂-C₆H₄ (R = 2,4,6-Me₃C₆H₂1, 2,4,5-Me₃C₆H₂2) reacts H₂/CO₂ to give formyl, acetal and methoxy-derivatives.