Induction of planar chirality in formation of (?(5):?(1)-1-(1-cyclohexyl-2-(diphenylphosphino)ethyl)indenyl)-carbonylrhodium and (?(5):?(1)-1-(2-phenyl-2-(diphenylphosphino)ethyl)indenyl)carbonylrhodium

Brookings, Daniel C., Harrison, Stephen A., Whitby, Richard J., Crombie, Barry and Jones, Ray V.H. (2001) Induction of planar chirality in formation of (?(5):?(1)-1-(1-cyclohexyl-2-(diphenylphosphino)ethyl)indenyl)-carbonylrhodium and (?(5):?(1)-1-(2-phenyl-2-(diphenylphosphino)ethyl)indenyl)carbonylrhodium. Organometallics, 20 (22), 4574-4583. (doi:10.1021/om010367s).

Abstract

The enantiopure bidentate indenyl-phosphine ligands (1S)-[2-(3H-inden-1-yl)-1-phenylethyl] diphenylphosphine (9) and [(2R)-2-cyclohexyl-2-(3H-inden-1-yl)ethyl]diphenylphosphine (18) were synthesized in 20% yield and three steps from (R)-styrene oxide and in 61% yield and four steps from vinylcyclohexane, respectively. In both cases ring opening of a spirocyclopropane-1,1'-indene with potassium diphenylphosphide was a key step. Addition of the lithium salts of 9 and 18 to [Rh(? -Cl)(CO)(2)](2) gave (?(5):?(1)-indenyl-CH2CH(Ph)PPh2)RhCO and (?(5):?(1)-indenyl-CH(Cy)CH2PPh2)RhCO as 75:25 and 78:22 mixtures of diastereoisomers, from which the major complexes were readily obtained by crystallization. The chiral centers in the linking chain ? and ? to the indenyl ring had thus induced good planar chirality of the complexed indenyl moiety. Both complexes were characterized by X-ray crystallography.

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Contributors

Author: Richard J. Whitby

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