| Publication Type |
Journal Article |
| Title |
Cu(I) catalysed cyclopropanation of olefins: Stereoselectivity studies with arylid-box and isbut-box ligands |
| Authors |
Anthony J. Burke Elisabete da Palma Carreiro Serghei Chercheja Nuno M. M. Moura J. P. Prates Ramalho Ana Isabel Rodrigues Carla. I. M. Santos |
| Groups |
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| Journal |
JOURNAL OF ORGANOMETALLIC CHEMISTRY |
| Year |
2007 |
| Month |
October |
| Volume |
692 |
| Number |
22 |
| Pages |
4863-4874 |
| Abstract |
In our quest to find new ligands for highly stereoselective reactions, we tested a variety of chiral non-racemic pseudo-C-2 symmetric bis-oxazolines derived from malonic acid containing an arylidene bridge unit (and appropriately termed Arylid-Box) in the catalytic asymmetric cyclopropanation (CAP) reaction of styrene and ethyl diazoacetate using between only 1-2 mol\% of a Cu(I) pre-catalyst. Some very good e.e.s (up to 86\%), were obtained. It was possible to isolate 10a -[Cu(CH3CN)(4)]PF6 which existed as a bench stable solid that proved to be more efficient than the catalyst prepared in situ. Cu(I) pre-catalysts were used for the first time in the CAP reaction with the Isbut-Box ligands 13a and 13b and, although, the e.e.s were better for ligand 13a using these pre-catalysts, in the case of ligand 11b this was not the case. Spectroscopic studies (UV-Vis and H-1 NMR) were carried out to gain an insight into the nature of the catalytic species at work so that the conditions could be optimised giving better results. Some theoretical studies were conducted to try to explain the better enantioselectivities obtained using Evans tert-Box-Cu(I) complex over our complex. (C) 2007 Elsevier B.V. All rights reserved. |
| DOI |
http://dx.doi.org/10.1016/j.jorganchem.2007.06.068 |
| ISBN |
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| Publisher |
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| Book Title |
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| ISSN |
0022-328X |
| EISSN |
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| Conference Name |
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| Bibtex ID |
ISI:000250741200008 |
| Observations |
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