Enantioselective hydroformylation of styrene without phosphorus ligands: catalysis with rhodium complexes of chiral thiourea

If phosphorus ligands have found a tremendous development for homogeneous catalysis, they sometimes offer disadvantages, like tedious synthesis or sensitivity toward air and moisture. Chiral thioureas have been synthesized and used as ligands for the asymmetric hydroformylation of styrene catalysed by rhodium (I) complexes. The best results were obtained with N-phenyl-N'-(S)-(1-phenylethyl)-thiourea associated with a cationic rhodium (I) precursor, and asymmetric induction of 40 % was then achieved.