R. V. Duren, Leandra L. J. M. Cornelissen, J. I. V. D. Vlugt
Aug 1, 2006
Citations
0
Influential Citations
30
Citations
Journal
Helvetica Chimica Acta
Abstract
The chiral diphosphonite ligand (11bR,11′bR)-4,4′-(9,9-dimethyl-9H-xanthene-4,5-diyl)bis[dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin] ((R,R)-XantBino; (R)-1), based on a rigid xanthene backbone, was applied in the Pt/Sn-catalyzed hydroformylation of styrene (4a), 4-methylstyrene (4b), vinyl acetate (4c), and allyl acetate (4d), by using a Pt/Sn ratio of 1 : 1. High ee of up to 80% were observed, along with good regioselectivities towards the desired branched aldehydes. For styrene, an interesting inversion in the stereoselection process was observed at elevated temperatures, and a mechanism is proposed considering the temperature dependence of the regioselectivity. The complex [PtCl2{(S,S)-XantBino}] ((S)-2) was characterized by X-ray crystal-structure analysis, revealing an unusual out-of-plane ligand coordination of the metal fragment. The complex [PtCl(SnCl3){(R,R)-XantBino}] ((R)-3) was characterized by means of 31P-NMR spectroscopy.