Solvent-Free Asymmetric Olefin Hydroformylation Catalyzed by Highly Cross-Linked Polystyrene-Supported (R,S)-BINAPHOS−Rh(I) Complex

Using an (R,S)-BINAPHOS−Rh(I) catalyst that is covalently anchored to a highly cross-linked polystyrene support, asymmetric hydroformylation of olefins was performed in the absence of organic solvents. The reaction of cis-2-butene, a gaseous substrate, provided (S)-2-methylbutanal with 100% regioselectivity and 82% ee upon treatment with H₂ (12 atm) and CO (12 atm) in a batchwise reactor equipped with a fixed bed. The polymer-supported catalyst was applicable to a continuous vapor-flow column reactor, and thus, 3,3,3-trifluoropropene was converted into (S)-2-trifluoromethylpropanal with an iso/normal ratio of 95/5 and 90% ee. Less volatile olefins, such as styrene, vinyl acetate, 1-alkenes, and fluorinated alkenes, were successfully converted into the corresponding isoaldehydes with high ee values, when they were injected through a supercritical CO₂-flow column reactor. Successive injection of a series of olefins realized the conversion of an olefin library into an optically active aldehyde library.