K. Nozaki, Nozomu Sakai, T. Nanno
May 14, 1997
Citations
0
Influential Citations
277
Citations
Quality indicators
Journal
Journal of the American Chemical Society
Abstract
A new chiral phosphine−phosphite ligand, (R)-2-(diphenylphosphino)-1,1‘-binaphthalen-2‘-yl (S)-1,1‘-binaphthalene-2,2‘-diyl phosphite [(R,S)-BINAPHOS, (R,S)-2a], was synthesized. Its Rh(I) complex was prepared, and its structure has been characterized by 1H and 31P NMR spectroscopy. Using Rh(I) complexes of (R,S)-2a and its enantiomer, highly enantioselective hydroformylation of styrene has been performed (94% ee, iso/normal = 88/12). The catalyst system was also effective for a variety of other olefins. Some other phosphine−phosphite ligands bearing 1,1‘-binaphthyl and biphenyl backbones, such as (S)-3,3‘-dichloro-6-(diphenylphosphino)-2,2‘,4,4‘-tetramethylbiphenyl-6‘-yl (R)-1,1‘-binaphthalene-2,2‘-diyl phosphite [(S,R)-BIPHEMPHOS, (S,R)-5a], (R,R)-2a, (R,S)-2b, (R)-2c, and (R)-5b, were tested for asymmetric hydroformylation. The results indicate that the sense of enantioface selection for the prochiral olefins is mainly determined by the absolute configuration of the phosphine site, for example, the (R)...