Enantioselective [2 + 2] Photocycloaddition via Iminium Ions: Catalysis by a Sensitizing Chiral Brønsted Acid
Franziska Pecho, Yeshua Sempere, Johannes Gramüller, Fabian M. Hörmann, Ruth M. Gschwind and Thorsten Bach*
*Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany,
Email: thorsten.bach
ch.tum.de
F. Pecho, Y. Sempere, J. Gramüller, F. M. Hörmann, R. M. Gschwind, T. Bach, J. Am. Chem. Soc., 2021, 143, 9350-9354.
DOI: 10.1021/jacs.1c05240
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Abstract
N,O-Acetals derived from α,β-unsaturated β-aryl substituted aldehydes and (1-aminocyclohexyl)methanol undergo a catalytic enantioselective [2 + 2] cycloaddition to a variety of olefins under visible light irradiation (λ = 459 nm). The photocycloaddition is catalyzed by a chiral phosphoric acid with thioxanthone moieties for a facile triplet energy transfer.
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Key Words
cyclobutanes, photochemistry, organocatalysis
ID: J48-Y2021
