Rhodium complexes with a new chiral amino-phosphinite ligand and their behavior as pre-catalysts in the hydroformylation of styrene

摘要

The new amino-phosphinite chiral ligand (S_a)-4-((S)-1-(diphenylphosphinooxy)-3-methylbutan-2-yl)-4,5-dihydro-3H-dinaphtho[2,1-c:1',2'-e]azepine (1) has been synthesized and the corresponding more stable oxide has been characterized by X-ray analysis. The ligand behavior in styrene hydroformylation using [Rh(acac)(CO)2] and [Rh(COD)2]BF4 as precursors has been studied. With both pre-catalysts, branched aldehyde 2-phenylpropanal was obtained in mild catalysis conditions with high yield and reg-ioselectivity but as racemic mixture, indicating the loss of the ligand (1) during catalytic run. To support these results, the reactions of [Rh(acac)(CO)2] and [Rh(COD)2]BF4 with the ligand 1 have been performed and the pre-catalysts behavior under CO/H2 has been investigated.