Highly Regioselective Isomerization-Hydroformylation of Internal Olefins Catalyzed by Rhodium/Tetraphosphine Complexes

A new class of substituted tetraphosphine ligands has been applied in the rhodium-catalyzed regioselective isomerization-hydroformylation of internal olefins. The rhodium/tetraphosphine ligand system is highly effective for the isomerization and hydroformylation of 2-alkenes to form linear aldehydes. Greater than 95% linear selectivity and up to 94% yield of the total aldehydes were obtained for 2-pentene, 2-hexene and 2-octene. The catalyst system also showed high to moderate linear selectivity for the isomerization and hydroformylation of 3-hexene, 3-octene and 4-octene but with slow reaction rates.