Phosphine-Borane Complexes: in situ Deprotection and Application as Ligands in the Rh- or Pd-Catalysed Hydroformylation Reaction

Triarylphosphine-borane complexes are directly useful in the Rh-catalysed hydroformylation reaction of 1-octene (or Pd-catalysed hydroformylation of 1-pentene). Mild reaction conditions provide similar yields and selectivities of the anticipated aldehyde products to reactions making use of the corresponding free phosphines as ligands. The mono- or bidentate P-B adducts undergo in situ CO-mediated deprotection the produce the free phosphine ligands. The results demonstrate that phosphine-borane complexes may be directly applied to carbonylation reactions without a prior deprotection step, with little to no change in the reaction outcome.