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Asymmetric Induction via a Helically Chiral Anion: Enantioselective Pentacarboxycyclopentadiene Brønsted Acid-Catalyzed Inverse-Electron-Demand Diels–Alder Cycloaddition of Oxocarbenium Ions

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journal contribution
posted on 27.02.2018, 00:00 by Chirag D. Gheewala, Jennifer S. Hirschi, Wai-Hang Lee, Daniel W. Paley, Mathew J. Vetticatt, Tristan H. Lambert
An enantioselective catalytic inverse-electron-demand Diels–Alder reaction of salicylaldehyde acetal-derived oxocarbenium ions and vinyl ethers to generate 2,4-dioxychromanes is described. Chiral pentacarboxycyclopentadiene (PCCP) acids are found to be effective for a variety of substrates. Computational and X-ray crystallographic analyses support the unique hypothesis that an anion with point-chirality-induced helical chirality dictates the absolute sense of stereochemistry in this reaction.