Vermeeren, PascalHamlin, TrevorFernández López, IsraelBickelhaupt, Matthias2024-02-212024-02-212020Vermeeren, Pascal, et al. «How Lewis Acids Catalyze Diels–Alder Reactions». Angewandte Chemie International Edition, vol. 59, n.o 15, abril de 2020, pp. 6201-06. https://doi.org/10.1002/anie.201914582.1433-785110.1002/anie.201914582https://hdl.handle.net/20.500.14352/101614The Lewis acid(LA)-catalyzed Diels–Alder reaction between isoprene and methyl acrylate was investigated quantum chemically using a combined density functional theory and coupled-cluster theory approach. Computed activation energies systematically decrease as the strength of the LA increases along the series I2 < SnCl4 < TiCl4 < ZnCl2 < BF3 < AlCl3. Emerging from our activation strain and Kohn–Sham molecular orbital bonding analysis was an unprecedented finding, namely that the LAs accelerate the Diels–Alder reaction by a diminished Pauli repulsion between the p-electron systems of the diene and dienophile. Our results oppose the widely accepted view that LAs catalyze the Diels–Alder reaction by enhancing the donor–acceptor [HOMOdiene–LUMOdienophile] interaction and constitute a novel physical mechanism for this indispensable textbook organic reaction.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/journal articlehttps://doi.org/10.1002/anie.201914582open access547Química orgánica (Química)2306 Química Orgánica