Palladium-catalyzed carbene migratory insertion using conjugated ene-yne-ketones as carbene precursors

Ying Xia, Shuanglin Qu, Qing Xiao, Zhi Xiang Wang, Peiyuan Qu, Li Chen, Zhen Liu, Leiming Tian, Zhongxing Huang, Yan Zhang, Jianbo Wang

Research output: Contribution to journalArticlepeer-review

113 Scopus citations

Abstract

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).

Original languageEnglish (US)
Pages (from-to)13502-13511
Number of pages10
JournalJournal of the American Chemical Society
Volume135
Issue number36
DOIs
StatePublished - Sep 11 2013

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