American Chemical Society
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Sc3+-Catalyzed Aldol-Type Additions of N-Benzoylcyclopropanecarboxamides via Iodide-Mediated Ring-Opening:  Stereoselective Synthesis of γ-Lactams

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posted on 2020-04-02, 13:42 authored by Sean H. Wiedemann, Hidetoshi Noda, Shinji Harada, Shigeki Matsunaga, Masakatsu Shibasaki
A new catalytic aldol-type addition of cyclopropanecarboximides to aldehydes via iodide-mediated ring-opening is presented. The reaction was found to be catalyzed at 0 °C using either a Sc(OTf)3/NaI system or ScI3. Stereoselective formation of α,α-disubstituted enolates occurred in situ. γ-Lactams bearing α-carbonyl quaternary stereocenters were obtained in 97−57% yield and dr = 90:10−80:20 after ring closure.