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Anion-π Catalysis of Diels-Alder Reactions |
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Published in | Angewandte Chemie: International Edition. 2017, vol. 56, no. 42, p. 13066-13069 | |
Abstract | Among concerted cycloadditions, the Diels–Alder reaction is the grand old classic, which is usually achieved with acid catalysis. In this report, hydroxypyrones, oxa-, and thiazolones are explored because they provide access to anionic dienes. Their [4+2] cycloaddition with cyclic and acyclic dienophiles, such as maleimides and fumarates, affords bicyclic products with four new stereogenic centers. Bifunctional anion–π catalysts composed of amine bases next to the π surface of naphthalenediimides (NDIs) are shown to selectively stabilize the “open”, fully accessible anionic exo transition state on the π-acidic aromatic surface. Our results also include reactivities that are hard to access with conventional organocatalysts, such as the exo-specific and highly enantioselective Diels–Alder reaction of thiazolones and maleimides with complete suppression of the otherwise dominant Michael addition. With increasing π acidity of the anion–π catalysts, the rates, chemo-, diastereo-, and enantioselectivities increase consistently. | |
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Research group | Groupe Matile | |
Citation (ISO format) | LIU, Le et al. Anion-π Catalysis of Diels-Alder Reactions. In: Angewandte Chemie: International Edition, 2017, vol. 56, n° 42, p. 13066-13069. doi: 10.1002/anie.201707730 https://archive-ouverte.unige.ch/unige:97331 |