Visible-Light-Mediated Enantioselective Photoreactions of 3‑Alkylquinolones with 4‑O‑Tethered Alkenes and Allenes
journal contributionposted on 22.04.2020 by Xinyao Li, Christian Jandl, Thorsten Bach
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The title compounds undergo intramolecular [2 + 2] photocycloaddition reactions when irradiated with visible light in the presence of a chiral sensitizer. Up to four defined stereogenic centers are formed in a single step (14 examples with a tethered alkene, 6 examples with an allene, 72–99% yield, 81–99% ee) at catalyst loadings as low as 0.5 mol %. The alkyl group in the 3-position is crucial for the success of the reaction as it leads to a significant decrease of the triplet energy.