A Dramatic Switch of Enantioselectivity in Asymmetric Heck Reaction by Benzylic Substituents of Ligands

A series of benzylic substituted P,N-ligands 1 and 2 have been synthesized. The Pd-complexes of these ligands show high catalytic activity and enantioselectivity in catalyzing the asymmetric Heck reaction. A dramatic switch in enantioselectivity is realized using ligands with and without substituent...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2008-07, Vol.130 (30), p.9717-9725
Main Authors: Wu, Wen-Qiong, Peng, Qian, Dong, Da-Xuan, Hou, Xue-Long, Wu, Yun-Dong
Format: Article
Language:English
Subjects:
Benzyl Compounds - chemistry
Catalysis
Crystallography, X-Ray
Furans - chemistry
Ligands
Models, Molecular
Palladium - chemistry
Pyrroles - chemistry
Rhenium - chemistry
Silicon - chemistry
Stereoisomerism
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Summary:A series of benzylic substituted P,N-ligands 1 and 2 have been synthesized. The Pd-complexes of these ligands show high catalytic activity and enantioselectivity in catalyzing the asymmetric Heck reaction. A dramatic switch in enantioselectivity is realized using ligands with and without substituents at the benzylic position of the ligand. Ligands 1 with H as the substituents offer products in (R)-configuration while ligands 2 with the methyl as substituents result in (S)-configuration products. In most cases high enantioselectivities are achieved. Density functional theory calculations on the reaction mechanism as well as X-ray analysis of 1a-PdCl2 and 2a-PdCl2 complexes provide a rational explanation for the above observations.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja7104174