Hydroformylation of functional alkenes with heterodonor phosphine rhodium catalysts: substrate or ligand directed regioselectivity?

The catalytic activity and selectivity of heterodonor phosphine rhodium cat alysts prepared in situ were tested in the hydroformylation of functional a lkenes (ethyl acrylate, methyl methacrylate, styrene, 4-vinyl-1-cyclohexene , dicyclopentadiene and cis-1.2,3.6-tetrahydrophthalic anhydride). Systemat ic variation of the heterodonor atom in the ortho position of the ligand sh owed that the heterodonor atom has a significant influence on the activitie s and selectivities of the reaction. However, the activity seems to depend mainly on the modifying ligand, and the regioselectivity mainly on the subs trate (i.e., the structure and functionality of the alkene). Nevertheless. regioselective control is only obtained through synergy between the substra te and the catalyst. Clear regiocontrol was observed in the hydroformylatio n of alpha, beta -unsaturated esters and styrene with an in situ formed o-( thiomethylphenyl)diphenylphosphine rhodium catalyst.