Aldehyde decarbonylation catalysis under mild conditions

Reaction of [RhCl(NBD)](2) with 2.0 equiv of triphos (triphos = bis(2-diphe nylphosphinoethyl)phenylphosphine; NBD = bicyclo[2.2.1]hepta-2,5-diene) in THF solution at room temperature affords [Rh(NBD)(triphos)][Cl] (4a), which was isolated as [Rh(NBD)(triphos)][SbF6] (4b) in 67% yield. Treatment of 4 b with aqueous formaldehyde in THF solution; at 80 degrees C forms [Rh(CO)( triphos)][SbF6] (2a), which reversibly binds a second equivalent of CO(g) t o give [Rh(CO)(2)(triphos)][SbF6] (2b). The complex [Rh(CO)(triphos)][SbF6] has been found to be an effective aldehyde decarbonylation catalyst for pr imary and aryl aldehydes at temperatures as low as that of refluxing dioxan e, with little or no undesirable side products resulting from beta eliminat ion or radical rearrangement.