Catalytic and Structural Studies on Complexes of a Binaphthyl-Phosphino-Oxazoline Auxiliary: The Meta Dialkyl Effect on Enantioselectivity

Kumaravel Selvakumar, Massimiliano Valentini, Paul S. Pregosin, Alberto Albinati, Frank Eisenträger

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The chiral phosphino-oxazoline ligand (S,R)-2-[4-(isopropyl)oxazol-2-yl]-2′-bis(3,5-dimethylphenylphosphino)-1, 1'-binaphthyl, 6b, its Pd-dichloro complex, 9, the p-cyanoaryl complex [PdBr(p-NC-C6H4](6b)], 10, a model for the Heck reaction, the cationic 1,3-diphenylallyl derivative [Pd(η3-PhCHCHCHPh)(6b)]OTf, 11, a model for the allylic allylation, and the Rh- and Ir-1,5-COD compounds [M(1,5-COD)(6b)]BF4, 12 and 13, respectively, have been prepared. In enantioselective catalytic experiments, the presence of the 3,5-dimethylphenyl groups generally increases the observed ee. The solid-state structure of PdCl2(6b), 9, has been determined. 2-D and variable-temperature NMR experiments suggest that one of the two 3,5-dimethyl P-aryl rings interacts selectively with the remaining ligands. Consequently, the entire chiral pocket becomes slightly more rigid and the correlation with substrate improves.

Original languageEnglish
Pages (from-to)1299-1307
Number of pages9
Issue number7
Publication statusPublished - Apr 3 2000


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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