Design principles in frustrated Lewis pair catalysis for the functionalization of carbon dioxide and heterocycles

This account describes our work on the use of ambiphilic molecules as catalysts for the reduction of carbon dioxide. Starting with the discovery that aluminum ambiphilic species (Me2PCH2AlMe2)2 (1) and AI (C6H4-PPh2)(3) (5) could coordinate CO2 but showed significant instability, we found that phosphinoborane Ph2P-2-Bcat-C6H4 (7) was an exceptional catalyst for the hydroboration-of CO2 to methoxyboranes, molecules that can be readily hydrolyzed to methanol. A mechanistic investigation allowed us to outline the similarities between the catalytic activity of frustrated Lewis pairs (FLPs) and that of transition metal complexes. We were able to extrapolate four important guidelines, described in this account, for the conception of efficient metal-free catalysts. We demonstrate that using these concepts, it was possible to rationally design FLP catalysts for the C-H borylation of heteroarenes. (C) 2016 Elsevier B.V. All rights reserved.