DUGi

Aryl-copper(III)-acetylides as key intermediates in Csp2-C sp model couplings under mild conditions

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@10204

The mechanism of copper-mediated Sonogashira couplings (so-called Stephens-Castro and Miura couplings) is not well understood and lacks clear comprehension. In this work, the reactivity of a well-defined aryl-Cu III species (1 ClO 4) with p-R-phenylacetylenes (R=NO2, CF3, H) is reported and it is found that facile reductive elimination from a putative aryl-CuIII-acetylide species occurs at room temperature to afford the Caryl - Csp coupling species (IR), which in turn undergo an intramolecular reorganisation to afford final heterocyclic products containing 2H-isoindole (PNO2, PCF3, PHa) or 1,2-dihydroisoquinoline (PHb) substructures. Density Functional Theory (DFT) studies support the postulated reductive elimination pathway that leads to the formation of C sp2-Csp bonds and provide the clue to understand the divergent intramolecular reorganisation when p-H-phenylacetylene is used. Mechanistic insights and the very mild experimental conditions to effect C aryl-Csp coupling in these model systems provide important insights for developing milder copper-catalysed Caryl - C sp coupling reactions with standard substrates in the future

We acknowledge financial support from European Research Council for Starting Grant Project ERC-2011-StG-277801 to X. R., MICINN of Spain (INNPLANTA project INP-2011-0059-PCT-420000-ACT1 to X. R., CTQ2012-32436 to T. P., CTQ2012-37420-C02-01/BQU to Dr. M. Costas, RyC contract to J.Ll.-F. and PhD FPI grant to M. F.), Consolider-Ingenio CSD2010-00065, and the Catalan DIUE of the Generalitat de Catalunya (2009SGR637). X. R. thanks an ICREA-Academia award

info:eu-repo/grantAgreement/MINECO//CTQ2012-37420-C02-01/ES/DISEÑO BIOINSPIRADO DE CATALIZADORES PARA LA OXIDACION DE ENLACES C-H, C=C Y AGUA/

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