Coordination of Lewis Acid to 2-Enonepalladium(0) Leading to Continuous Structure Variation from 
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- 作者：Sensuke Ogoshi ; Tomohiro Yoshida ; Takuma Nishida ; Masaki Morita ; and Hideo Kurosawa
- 刊名：Journal of the American Chemical Society
- 出版年：2001
- 出版时间：March 7, 2001
- 年：2001
- 卷：123
- 期：9
- 页码：1944 - 1950
- 全文大小：114K
- 年卷期：v.123,no.9(March 7, 2001)
- ISSN：1520-5126
文摘
The reaction of 
,
-unsaturated carbonyl compounds, a palladium(0) complex, and Lewis acids ledto the formation of a new class of complexes showing a wide variety of structures with 
2-type and 3-typecoordination of the carbonyl compounds. The reaction of Pd(PhCH=CHCOCH3)(PPh3)2 with BF3·OEt2 orB(C6F5)3 quantitatively gave palladium complexes 1a,b having BX3-coordinated 2-enonepalladium structure,as revealed by X-ray structure analysis of the B(C6F5)3 adduct 1b. On the other hand, the reaction of Pd(PhCH=CHCHO)(PPh3)2 with BF3·OEt2 or B(C6F5)3 gave distorted zwitterionic 3-allylpalladium complexes3a,b, where the Pd-carbonyl carbon distance in 3a (2.413(4) Å) is much shorter than that (2.96(1) Å) in 1b.The values of the P-P coupling constant and 13C chemical shift for carbonyl carbon are useful criteria forpredicting how the 3-coordination mode contributes to the structure of the enone-palladium-Lewis acidsystem. Molecular orbital calculations on the series of model complexes suggest that orbital overlap in thehighest occupied molecular orbital between the palladium and carbonyl carbon is enlarged by coordination ofthe Lewis acid to the carbonyl group. Palladium-catalyzed conjugate addition of R-M (R-M = AlMe3, AlEt3,ZnEt2) and its plausible reaction path are also reported.
,-unsaturated carbonyl compounds, a palladium(0) complex, and Lewis acids ledto the formation of a new class of complexes showing a wide variety of structures with 2-type and 3-typecoordination of the carbonyl compounds. The reaction of Pd(PhCH=CHCOCH3)(PPh3)2 with BF3·OEt2 orB(C6F5)3 quantitatively gave palladium complexes 1a,b having BX3-coordinated 2-enonepalladium structure,as revealed by X-ray structure analysis of the B(C6F5)3 adduct 1b. On the other hand, the reaction of Pd(PhCH=CHCHO)(PPh3)2 with BF3·OEt2 or B(C6F5)3 gave distorted zwitterionic 3-allylpalladium complexes3a,b, where the Pd-carbonyl carbon distance in 3a (2.413(4) Å) is much shorter than that (2.96(1) Å) in 1b.The values of the P-P coupling constant and 13C chemical shift for carbonyl carbon are useful criteria forpredicting how the 3-coordination mode contributes to the structure of the enone-palladium-Lewis acidsystem. Molecular orbital calculations on the series of model complexes suggest that orbital overlap in thehighest occupied molecular orbital between the palladium and carbonyl carbon is enlarged by coordination ofthe Lewis acid to the carbonyl group. Palladium-catalyzed conjugate addition of R-M (R-M = AlMe3, AlEt3,ZnEt2) and its plausible reaction path are also reported.