Mechanism of the Selective Fe-Catalyzed Arene Carbon-Hydrogen Bond Functionalization
The complete chemoselective functionalization of aromatic C(sp(2))-H bonds of benzene and alkyl benzenes by carbene insertion from ethyl diazoacetate was unknown until the recent discovery of an iron-based catalytic system toward such transformation. A Fe(II) complex bearing the pytacn ligand (pytac...
| Autores: | , , , , , , , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2018 |
| País: | España |
| Recursos: | Universidad de Huelva (UHU) |
| Repositório: | Arias Montano. Repositorio Institucional de la Universidad de Huelva |
| Idioma: | inglês |
| OAI Identifier: | oai:ariasmontano.uhu.es:10272/15970 |
| Acesso em linha: | http://hdl.handle.net/10272/15970 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Carbene transfer Iron catalysis C-H activation C(sp(2))-H functionalization DFT calculations |
| Resumo: | The complete chemoselective functionalization of aromatic C(sp(2))-H bonds of benzene and alkyl benzenes by carbene insertion from ethyl diazoacetate was unknown until the recent discovery of an iron-based catalytic system toward such transformation. A Fe(II) complex bearing the pytacn ligand (pytacn = L1 = 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane) transferred the CHCO2Et unit exclusively to the C(sp(2))-H bond. The cycloheptatriene compound commonly observed through Buchner reaction or, when employing alkyl benzenes, the corresponding derivatives from C(sp(3))-H functionalization are not formed. We herein present a combined experimental and computational mechanistic study to explain this exceptional selectivity. Our computational study reveals that the key step is the formation of an enol-like substrate, which is the precursor of the final insertion products. Experimental evidences based on substrate probes and isotopic labeling experiments in favor of this mechanistic interpretation are provided. |
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