Pd, Rh-Catalyzed Regioselective Hydroformylation of Olefins with Formic Acid and Its Salts

Efficient Pd- or Rh-catalyzed regioselective hydroformylation processes with HCO₂Na/Ac₂O or HCO₂H/Ac₂O are described. The linear aldehydes can be obtained in good yields with high l/b ratios. These two systems (HCO₂Na/Ac₂O vs HCO₂H/Ac₂O) give generally comparable results with their own advantages for certain substrates. In general, the Pd-catalyzed formylation reaction gives higher regioselectivities for vinyl arenes, while the Rh-catalyzed process gives higher regioselectivities for certain alkyl terminal olefins. All of these formylation processes are simple to operate and provide complementary methods for the synthesis of aldehydes from olefins.