A Bimetallic Palladium Catalyst for Asymmetric Allylic Substitution Reactions
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- 作者：Urs Burckhardt ; Markus Baumann ; Gerald Trabesinger ; Volker Gramlich ; and Antonio Togni
- 刊名：Organometallics
- 出版年：1997
- 出版时间：November 25, 1997
- 年：1997
- 卷：16
- 期：24
- 页码：5252 - 5259
- 全文大小：244K
- 年卷期：v.16,no.24(November 25, 1997)
- ISSN：1520-6041
文摘
With 1,1'-diacetylruthenocene (9) as starting material,the preparation of 1,1'-bis[1-(1-{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl})-1H-pyrazol-3-yl]ruthenocene((R,R)-(S,S)-12) is attained in three steps. 12coordinates to two independent Pd(II)-
-allyl unitstoform the dicationic complex 15, isolated as abis(hexafluorophosphate) salt. This has beencharacterized by X-ray and 2D NMR methods in solution, along with theanalogous derivative14, which contains1-{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}-3-ruthenocenyl-1H-pyrazole ((R)-(S)-8b). The threePd(II)-allyl fragments in these two complexes showverysimilar conformational features. In the Pd-catalyzed substitutionreaction of ethyl (1,3-diphenylallyl)carbonate (1) with benzylamine, thebimetallic catalyst containing ligand 12and the mononuclear catalyst formed by 8b afford the samehigh enantioselectivity (99.3%).
-allyl unitstoform the dicationic complex 15, isolated as abis(hexafluorophosphate) salt. This has beencharacterized by X-ray and 2D NMR methods in solution, along with theanalogous derivative14, which contains1-{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}-3-ruthenocenyl-1H-pyrazole ((R)-(S)-8b). The threePd(II)-allyl fragments in these two complexes showverysimilar conformational features. In the Pd-catalyzed substitutionreaction of ethyl (1,3-diphenylallyl)carbonate (1) with benzylamine, thebimetallic catalyst containing ligand 12and the mononuclear catalyst formed by 8b afford the samehigh enantioselectivity (99.3%).