Tandem Carbonylation Reactions:  Hydroformylation and Hydroaminomethylation of Alkenes Catalyzed by Cationic [(H₂C(3,5-Me₂pz)₂)Rh(CO)L]⁺Complexes

Addition of H 2 C(3,5-Me 2 pz) 2 (Bpm*) to [(η 4 -1,5-COD)Rh(acetone) 2 ]BF 4 affords the complex [Bpm*Rh(COD)]BF 4, which is carbonylated under mild conditions into [Bpm*Rh(CO) 2 ]BF 4 . One of the CO ligands can be easily displaced by PPh 3, PMePh 2, or P(OMe) 3 . The X-ray structures of [Bpm*Rh(CO) 2 ]BF 4 and [Bpm*Rh(CO)(PPh 3 )]BF 4 have been determined and show a rhodium center in a square-planar environment. These complexes have been fully characterized by infrared and 1 H, 13 C, and 31 P 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/NHEt 2 building blocks. The reaction rate can be significantly increased on addition of [RuH 2 (PPh 3 ) 4 ], which acts presumably as a hydride-donating species.