Five-Coordinate [RuCl(P−P*)2]+ Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins
| Autor: | Antonio Mezzetti, Patrick D. Setz, and Terrance Y. H. Wong, Christian Bauer, Robert M. Stoop, Michael Wörle |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Organometallics. 18:5691-5700 |
| ISSN: | 1520-6041 0276-7333 |
| DOI: | 10.1021/om990657x |
| Popis: | The six-coordinate complexes trans-[RuCl2(P−P*)2] (P−P* = (S,S)-1,2-bis(1-naphthylphenylphosphino)ethane (bnpe), 2a; (S,S)-2,3-bis(diphenylphosphino)butane (chiraphos), 2b) have been prepared and structurally characterized. The X-ray studies of 2a,b show non-C2-symmetric conformations of the substituents at the PPh2 groups in a highly crowded octahedral environment. Complexes 2a,b react with Tl[PF6] in CH2Cl2 to give the corresponding monochloro, cationic derivatives [RuCl(P−P*)2]PF6 (P−P* = bnpe, 3a; chiraphos, 3b). The bnpe derivative 3a is five-coordinate both in the solid state (by X-ray investigation) and in solution (by 31P NMR spectroscopy). The chiraphos analogue 3b apparently dimerizes in solution, depending on the solvent (CDCl3 or CD2Cl2) and on the concentration. Complexes 3a,b catalyze the decomposition of ethyl diazoacetate to give, in the presence of styrene, the corresponding cyclopropanation products with enantioselectivity up to 35% ee and E/Z ratios of about 55:45. Complexes 3a,b also c... |
| Databáze: | OpenAIRE |
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