Reaction mechanisms involved in cross coupling processes catalysed by copper and nickel
Organometallic aryl-CuIII species have been proposed as key intermediates in Ullmann-type reactions. However, such species have long remained elusive and mechanistic investigations of a plausible catalytic cycle remained ambiguous and speculative. The first part of this thesis deals with the reactiv...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/403434 |
| Acceso en línea: | http://hdl.handle.net/10803/403434 |
| Access Level: | acceso abierto |
| Palabra clave: | Copper catalysis Catàlisi de coure Catálisis de cobre Nickel catalysis Catàlisi de níquel Catálisis de níquel Cross coupling chemistry Acoblament creuat Acoplamiento cruzado Ullmann chemistry Química d'Ullmann Química de Ullmann Chemoselectivity Quimioselectivitat Quimioselectividad C-C bond formation Formació d'enllaços C-C Formación de enlaces C-C 54 |
| Sumario: | Organometallic aryl-CuIII species have been proposed as key intermediates in Ullmann-type reactions. However, such species have long remained elusive and mechanistic investigations of a plausible catalytic cycle remained ambiguous and speculative. The first part of this thesis deals with the reactivity of well-defined aryl-CuIII macrocyclic complex in presence of activated methylenes (Hurtley-type coupling) and terminal acetylenes (Stephens-Castro-type coupling). The subsequent part deals with the synthesis and fully characterization of well-defined aryl-NiII complex, which is analogous to aryl-CuIII complex. The strength of the Ni-C bond precludes their direct reactivity with nucleophiles via reductive elimination. Nevertheless, we have proved their reactivity in the presence of a 2 e- redox oxidant as an electrophilic CF3+ source. In the last part, we turned our attention to the standard Cu-catalyzed Ullmann-type reactions by studying the effect of the ligand choice on the chemoselectivity of a multiple combinations of amides, amines and phenols in competitive reactions |
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