Rhodium-catalyzed linear selective hydroformylation of trisubstitued alkenes

Abstract

Rh-catalyzed hydroformylation of trisubstituted alkenes was investigated with bicyclic bridgehead phosphoramidite (briphos) ligands. Because trisubstituted alkenes are one of challenging substrates for hydro-formylation reaction. The efficient catalysts or conditions have not been reported. When the reaction was performed with various ligands including triphenylphosphine, tri-phenylphosphite, and briphos ligands derived from 2,2’-dihydroxybenzophenone, the reaction conversion was low. In order to improve the catalytic activity, we synthesized new briphos ligands with bulky tert-butyl groups on the backbone. With the new bulky briphos ligand, we could achieve high reactivity and selectivity for the hydroformylation of tri-substituted alkenes including 1-methyl-1-cyclohexene, 1-phenyl-1-cyclohexne and prenyl acetate.