Three ortho-palladated complexes were tested as chiral derivatizing agents for enantiomeric excess determination of monodentate P-*-chiral phosphines by P-31 NMR analysis. The complexes containing a bulky substituent at the alpha-C-* - 1e or an N-*-stereocentre 1d are shown to be more efficient as compared to known N-achiral alpha-methyl substituted analogues. The structure and stereochemistry of the new dimeric complex (S-c)-1e was established by X-ray analysis. (C) 1997 Published by Elsevier Science Ltd.
Synthesis of asymmetric secondary phosphines by the cross coupling of arylhalides with silylphosphines
作者:I. P. Beletskaya、Yu. A. Veits、V. A. Leksunkin、V. L. Foss
DOI:10.1007/bf00864195
日期:1992.7
The cross coupling of aryl halides with alkyl(trimethylsilyl)phosphines catalyzed by zero-valent palladium complexes yields secondary alkylarylphosphoranes containing both electron-donor and electron-withdrawing substituents in the aromatic ring. The reversible disproportionation of alkylsilylphosphines to give AlkPH2 and AlkP(SiMe3)2 was observed for the first time during this reaction. This disproportionation does not affect the yield of AlkArPH, which are formed in virtually quantitative yield, due to the high rate of cross coupling with AlkP(SiMe3)H2 and the reversibility of the disproportionation process.