Pd-Catalyzed Carbonylation of Diazo Compounds at Atmospheric Pressure: A Catalytic Approach to Ketenes

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• 作者：Zhenhua Zhang ; Yiyang Liu ; Lin Ling ; Yuxue Li ; Yian Dong ; Mingxing Gong ; Xiaokun Zhao ; Yan Zhang ; Jianbo Wang
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：March 30, 2011
• 年：2011
• 卷：133
• 期：12
• 页码：4330-4341
• 全文大小：1256K
• 年卷期：v.133,no.12(March 30, 2011)
• ISSN：1520-5126

文摘

The carbonylation of carbenes through catalytic cycles is highly desirable due to the importance of ketene-mediated reactions in organic synthesis. In this investigation, a highly efficient and mild catalytic approach toward ketene intermediates has been developed based on Pd-catalyzed carbonylation of diazo compounds with CO. When 伪-diazocarbonyl compounds or N-tosylhydrazone salts are heated in the presence of a palladium catalyst under atmospheric pressure of CO, ketene intermediates are formed in situ, where they undergo further reactions with various nucleophiles such as alcohols, amines, or imines. The Pd-catalyzed tandem carbonylation鈭扴taudinger cycloaddition gives 尾-lactam derivatives in good yields with excellent trans diastereoselectivity. The results from DFT calculation on the reaction mechanism suggest that Pd is involved in the [2 + 2] cycloaddition process and affects the diastereoselectivity of the 尾-lactam products by assisting isomerization of the addition intermediate. On the other hand, the acylketenes generated from the Pd-catalyzed carbonylation of 伪-diazoketones react with imines in a formal [4 + 2] cycloaddition manner to afford 1,3-dioxin-4-one derivatives. This straightforward carbonylation provides a new approach toward highly efficient catalytic generation of ketene species under mild conditions.