Asymmetric Cascade Annulation Based on Enantioselective Oxa-Diels鈥揂lder Cycloaddition of in Situ Generated Isochromenyliums by Cooperative Binary Catalysis of Pd(OAc)2 and (S)-Trip
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- 作者：Shu-Yan Yu ; Hao Zhang ; Yang Gao ; Lei Mo ; Shaozhong Wang ; Zhu-Jun Yao
- 刊名：The Journal of the American Chemical Society
- 出版年：2013
- 出版时间：July 31, 2013
- 年：2013
- 卷：135
- 期：30
- 页码：11402-11407
- 全文大小：484K
- 年卷期：v.135,no.30(July 31, 2013)
- ISSN：1520-5126
文摘
An asymmetric cascade annulation between 2-hydroxystyrenes and 2-alkynylbenaldehyes or 1-(2-alkynylphenyl)ketones has been established with good to excellent enantioselectivities (up to >99.5% ee), on the basis of an enantioselective oxa-Diels鈥揂lder cycloaddition of in situ generated metallo-isochromenylium intermediates, by cooperative binary catalysis of Pd(OAc)2 and (S)-Trip. The developed methodology is workable for a broad spectrum of substrates and shows great efficiency in establishing dense multiple chiral centers including quaternary carbons of variable bridged ring systems. The mechanism study suggests that (S)-Trip plays multiple roles in assembling the reactants and controlling the stereoselectivity.