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Title: Combined Experimental and Computational Investigations of Rhodium Catalysed C—H Functionalisation of Pyrazoles with Alkenes
Authors: Davies, David L.
Algarra, Andres G.
Khamker, Qudsia
Macgregor, Stuart A.
McMullin, Claire L
Villa-Marcos, Barbara
Singh, Kuldip
First Published: 17-Dec-2014
Publisher: Wiley-VCH Verlag GmbH & Co. KGaA. for ChemPubSoc Europe
Citation: Chemistry - A European Journal, 2015, 21 (7), pp 3087 - 3096
Abstract: Detailed experimental and computational studies have been carried out on the oxidative coupling of the alkenes C2H3Y (Y=CO2Me (a), Ph (b), C(O)Me (c)) with 3-aryl-5-R-pyrazoles (R=Me (1 a), Ph (1 b), CF3 (1 c)) using a [Rh(MeCN)3Cp*][PF6]2/Cu(OAc)2⋅H2O catalyst system. In the reaction of methyl acrylate with 1 a, up to five products (2 aa–6 aa) were formed, including the trans monovinyl product, either complexed within a novel CuI dimer (2 aa) or as the free species (3 aa), and a divinyl species (6 aa); both 3 aa and 6 aa underwent cyclisation by an aza-Michael reaction to give fused heterocycles 4 aa and 5 aa, respectively. With styrene, only trans mono- and divinylation products were observed, whereas with methyl vinyl ketone, a stronger Michael acceptor, only cyclised oxidative coupling products were formed. Density functional theory calculations were performed to characterise the different migratory insertion and β-H transfer steps implicated in the reactions of 1 a with methyl acrylate and styrene. The calculations showed a clear kinetic preference for 2,1-insertion and the formation of trans vinyl products, consistent with the experimental results.
DOI Link: 10.1002/chem.201405550
ISSN: 0947-6539
eISSN: 1521-3765
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons At- tribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Appears in Collections:Published Articles, Dept. of Chemistry

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