- Palladium-Catalyzed Oxidative Cross-Coupling of Conjugated Enynones with Allylarenes: Synthesis of Furyl-Substituted 1,3-Dienes
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A new method for the synthesis of furyl-substituted 1,3-dienes via palladium-catalyzed oxidative cross-coupling of conjugated enynones with allylarenes is developed. This reaction shows broad substrate scope and good functional group tolerance. Palladium carbene migratory insertion is proposed as the key step for this transformation with conjugated enynones serving as the carbene precursors.
- Ping, Yifan,Zhang, Sudong,Chang, Taiwei,Wang, Jianbo
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p. 8275 - 8283
(2019/06/17)
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- Palladium-catalyzed carbene migratory insertion using conjugated ene-yne-ketones as carbene precursors
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Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratory insertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate, which is supported by DFT calculations. The palladium carbene character of the key intermediate is validated by three aspects, including bond lengths, Wiberg bond order indices, and molecular orbitals, by comparison to those reported for stable palladium carbene species. Computational studies also revealed that the rate-limiting step is ene-yne-ketone cyclization, which leads to the formation of the palladium (2-furyl)carbene, while the subsequent carbene migratory insertion is a facile process with a low energy barrier (5 kcal/mol).
- Xia, Ying,Qu, Shuanglin,Xiao, Qing,Wang, Zhi-Xiang,Qu, Peiyuan,Chen, Li,Liu, Zhen,Tian, Leiming,Huang, Zhongxing,Zhang, Yan,Wang, Jianbo
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p. 13502 - 13511
(2013/09/24)
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