Experimental and Computational Evidence for Gold Vinylidenes: Generation from Terminal Alkynes via a Bifurcation Pathway and Facile C鈥揌 Insertions
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- 作者：Longwu Ye ; Yanzhao Wang ; Donald H. Aue ; Liming Zhang
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：January 11, 2012
- 年：2012
- 卷：134
- 期：1
- 页码：31-34
- 全文大小：405K
- 年卷期：v.134,no.1(January 11, 2012)
- ISSN：1520-5126
文摘
Facile cycloisomerization of (2-ethynylphenyl)alkynes is proposed to be promoted synergistically by two molecules of BrettPhosAuNTf2, affording tricyclic indenes in mostly good yields. A gold vinylidene is most likely generated as one of the reaction intermediates on the basis of both mechanistic studies and theoretical calculations. Different from the well-known Rh, Ru, and W counterparts, this novel gold species is highly reactive and undergoes facile intramolecular C(sp3)鈥揌 insertions as well as O鈥揌 and N鈥揌 insertions. The formation step for the gold vinylidene is predicted theoretically to be complex with a bifurcated reaction pathway. A pyridine N-oxide acts as a weak base to facilitate the formation of an alkynylgold intermediate, and the bulky BrettPhos ligand in the gold catalyst likely plays a role in sterically steering the reaction toward formation of the gold vinylidene.