Palladium‐ and Ruthenium‐Catalyzed Intramolecular Carbene CAr−H Functionalization of γ‐Amino‐α‐diazoesters for the Synthesis of Tetrahydroquinolines
A synthetic method to prepare tetrahydroquinoline‐4‐carboxylic acid esters has been developed through the transition‐metal‐catalyzed intramolecular aromatic C−H functionalization of α‐diazoesters. Both [{Pd(IMes)(NQ)}2] (IMes=1,3‐dimesitylimidazol‐2‐ylidene, NQ=1,4‐naphthoquinone) and the first‐gene...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/157660 |
| Acceso en línea: | https://hdl.handle.net/2445/157660 |
| Access Level: | acceso abierto |
| Palabra clave: | Catalitzadors metàl·lics Èsters Metal catalysts Esters |
| Sumario: | A synthetic method to prepare tetrahydroquinoline‐4‐carboxylic acid esters has been developed through the transition‐metal‐catalyzed intramolecular aromatic C−H functionalization of α‐diazoesters. Both [{Pd(IMes)(NQ)}2] (IMes=1,3‐dimesitylimidazol‐2‐ylidene, NQ=1,4‐naphthoquinone) and the first‐generation Grubbs catalyst proved effective for this purpose. The ruthenium catalyst was found to be the most versatile, although in a few cases the palladium complex afforded better yields or selectivities. According to DFT calculations, Pd0‐ and RuII‐catalyzed sp2‐CAr−H functionalization proceeds through different reaction mechanisms. Thus, the Pd0‐catalyzed reaction involves a Pd‐mediated 1,6‐H migration from the sp2‐CAr−H bond to the carbene carbon atom, followed by a reductive elimination process. In contrast, electrophilic addition of the ruthenacarbene intermediate to the aromatic ring and subsequent 1,2‐proton migration are operative in the Grubbs catalyst promoted reaction. |
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