Synthesis of enantioenriched γ-quaternary cycloheptenones using a combined allylic alkylation/Stork–Danheiser approach: preparation of mono-, bi-, and tricyclic systems
A general method for the synthesis of β-substituted and unsubstituted cycloheptenones bearing enantioenriched all-carbon γ-quaternary stereocenters is reported. Hydride or organometallic addition to a seven-membered ring vinylogous ester followed by finely tuned quenching parameters achieves elimination to the corresponding cycloheptenone. The resulting enones are elaborated to bi- and tricyclic compounds with potential for the preparation of non-natural analogs and whose structures are embedded in a number of cycloheptanoid natural products.
Additional Information© 2011 The Royal Society of Chemistry. Received 17 Jul 2011, Accepted 27 Aug 2011. First published on the web 01 Sep 2011. This publication is based on work supported by Award No. KUS-11-006-02, made by King Abdullah University of Science and Technology (KAUST). The authors wish to thank NIH-NIGMS (R01GM080269-01), Amgen, Abbott, Boehringer Ingelheim, and Caltech for financial support. AMH thanks the NIH for a postdoctoral fellowship. Materia, Inc. is gratefully acknowledged for the donation of catalysts. Michael Krout, Thomas Jensen, Christopher Henry, Scott Virgil, and Sarah Reisman are acknowledged for helpful discussions. David VanderVelde is acknowledged for critical NMR support.
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