Phosphine catalyzed reduction of CO2 with boranes

Phosphine is shown to catalyse the reaction of CO2 with 9-BBN to give mixtures of HCO2(B(C8H14)) 3, H2C(OB(C8H14))(2) 4 and MeOB(C8H14) 5; at 0.02 mol% of tBu(3)P 5 is obtained in 98% yield at 60 degrees C with TON of almost 5500 and a TOF of 170. Under stoichiometric conditions the species (R3PCH2O)(HC(O)O)B(C8H14) (R = tBu 1,4-MeC6H4 2) were isolated and characterized.