Optically active rhodium complexes with indenyl-linked phosphane ligands

The optically active indenyl-linked phosphane ligands (S)-[2-(3H-inden-1-yl)-1-phenylethyl]diphenylphosphane (L-1) and (S)-[2-(4,7-dimethyl-3H-inden-1-yl)-1-phenyl-ethyl]diphenylphosphane (L-2) were synthesized in three steps from (R)-1-phenylethane-1,2-diol in excellent yields. Their lithium salts reacted with [Rh(mu-Cl)(eta(2)-CH2CH2)(2)](2) at -78 degrees C in THF affording the planar chiral complexes (S,R-Pt+S-pt)-[Rh(eta(5)-indenyl-CH2CH(Ph)PPh2-kP)(eta(2)-CH2CH2)] and (S,R-Pt+S-pt)-[Rh(eta(5)-4,7-dimethylindenyl-CH2CH(Ph)PPh2-kP)(eta(2)-CH2CH2)] as 61:39 and 15:85 mixtures of diastereomers. The complexes were isolated in optically pure form by column chromatography. The stereochemical configuration of one of the diastereomers was determined by X-ray crystallography. The complexation of L-2 was studied in different solvents and with several Rh precursors and diastereomeric excesses up to 76% were achieved. The ability of the chiral ligands to control the stereochemistry at the metal center was tested by oxidative addition of methyl iodide. Diastereomeric excesses greater than 98% were observed. (C) 2007 Elsevier B.V. All rights reserved.