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Ligand-Enabled γ-C(sp3)–H Olefination of Free Carboxylic Acids
preprintsubmitted on 14.02.2020, 21:24 and posted on 18.02.2020, 11:43 by Kiron Kumar Ghosh, Alexander Uttry, Francesca Ghiringhelli, Arup Mondal, Manuel van Gemmeren
We report the ligand enabled C(sp3)–H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael-addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.