Design of a highly active Pd catalyst with P,N hemilabile ligands for alkoxycarbonylation of alkynes and allenes : a density functional theory study
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In palladium-catalysed methoxycarbonylation of technical propyne, the presence of propadiene poisons the hemilabile Pd(P,N) catalyst. According to density functional theory calculations (B3PW91-D3/PCM level), a highly stable π-allyl intermediate is the reason for this catalyst poisoning. Predicted regioselectivities suggest that at least 11% of propadiene should yield this allyl intermediate, where the reaction gets stalled under the turnover conditions due to an insurmountable methanolysis barrier of 25.8 kcal mol-1. Results obtained for different ligands and substrates are consistent with the available experimental data. A new ligand, (6-Cl-3-Me-Py)PPh2, is proposed, which is predicted to efficiently control the branched/linear selectivity, avoiding rapid poisoning (with only 0.2% of propadiene being trapped as Pd allyl complex), and to tremendously increase the catalytic activity by decreasing the overall barrier to 9.1 kcal mol-1.
Ahmad , S & Buehl , M 2019 , ' Design of a highly active Pd catalyst with P,N hemilabile ligands for alkoxycarbonylation of alkynes and allenes : a density functional theory study ' , Chemistry - A European Journal , vol. 25 , no. 50 , pp. 11625-11629 . https://doi.org/10.1002/chem.201902402
Chemistry - A European Journal
Copyright © 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1002/chem.201902402
DescriptionAuthors thanks EaStCHEM and the School of Chemistry for support.
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