Auto-Tandem Catalysis in the Synthesis of Substituted Quinolines from Aldimines and Electron-Rich Olefins: Cascade Povarov−Hydrogen-Transfer Reaction
journal contributionposted on 03.10.2008 by Naoya Shindoh, Hidetoshi Tokuyama, Yoshiji Takemoto, Kiyosei Takasu
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We demonstrated a catalytic cascade inverse electron demand hetero-Diels−Alder reaction (Povarov reaction) and hydrogen-transfer process. The reaction of electron-rich olefins and excess amount of imines in the presence of acid catalysts under appropriate conditions affords substituted quinolines in a single operation. In the cascade process, the catalysts, such as Tf2NH, TfOH, and Lewis acids, catalyze two mechanistically distinct reactions (auto-tandem catalysis). We also describe the synthetic utility of the prepared quinolines.