Tandem carbonylation reactions:: Hydroformylation and hydroaminomethylation of alkenes catalyzed by cationic [(H2C(3,5-Me2pz)2)Rh(CO)L]+ complexes

Addition of H2C(3,5-Me(2)pz)(2) (Bpm*) to [(eta(4)-1,5-COD)Rh(acetone)(2)]BF4 affords the complex [Bpm*Rh(COD)]BF4, which is carbonylated under mild conditions into [Bpm*Rh(CO)(2)]BF4. One of the CO ligands can be easily displaced by PPh3, PMePh2, or P(OMe)(3). The X-ray structures of [Bpm*Rh(CO)(2)]BF4 and [Bpm*Rh(CO)(PPh3)]BF4 have been determined and show a rhodium center in a square-planar environment. These complexes have been fully characterized by infrared and H-1, C-13, and P-31 NMR spectroscopy. They are rather active precursors for the hydroformylation of oct-1-ene. They also promote the hydroaminomethylation reaction of terminal alkenes: i.e., the direct production of alkylamines from successive hydroformylation, condensation of the resulting aldehydes with diethylamine, and hydrogenation of the enamines. (2-Methyloctyl)diethylamine and nonyldiethylamine are obtained from oct-1-ene/H-2/CO/NHEt2 building blocks. The reaction rate can be significantly increased on addition of [RuH2(PPh3)(4)], which acts presumably as a hydride-donating species.