Reductive Cleavage of the CO Molecule by a Reactive Vicinal Frustrated PH/BH Lewis Pair.

A dimeric ethylene-bridged PH/BH system reduced carbon monoxide to the -CH2-O- state. In the presence of B(C6F5)3, the frustrated PH/BH Lewis pair reacted with carbon monoxide by reductive coupling of two CO molecules at the template. Removal of the B(C6F5)3 borane with pyridine liberated one equiv of carbon monoxide to give a cyclic five-membered P(═O)-CH2-B compound, the product of reductive cleavage of carbon monoxide. It reacted as a borylated Horner P(═O)CH2B carbon nucleophile with carbon dioxide to give a bicyclic product by P-CH2 attack on CO2 combined with internal P═O to boron coordination.