Enantioselective Synthesis of the 5–6–7 Carbocyclic Core of the Gagunin Diterpenoids
A catalytic enantioselective double allylic alkylation reaction has been employed in the synthesis of the core of the gagunin diterpenoids. Enantioenriched material was advanced in 11 steps to afford the core of the highly oxygenated target, which includes two all-carbon quaternary stereocenters.
Additional Information© 2013 American Chemical Society. Received May 29, 2013. Published on Web 06/26/2013. The authors wish to thank NIH-NIGMS (R01GM080269-01), Amgen, Abbott, Boehringer Ingelheim, and Caltech for financial support. Mr. Austin Moehle (Caltech) is thanked for the preparation of early compounds. Dr. David Vander Velde (Caltech) is gratefully acknowledged for assistance with the characterization of compounds by NMR spectroscopy. Mr. Lawrence Henling (Caltech) is gratefully acknowledged for X-ray crystallographic structural determination and Dr. Alexander Goldberg (Caltech) is acknowledged for assisting in the preparation of crystallographic images for publication. Ms. Kelly Kim (Caltech) is acknowledged for assistance with the IR data of a late-stage compound. Materia, Inc. and Dr. Keith Keitz (Caltech) are thanked for the generous donation of ruthenium catalysts. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology, CHE-0639094. We also wish to acknowledge helpful discussions with Christina White (UIUC), Huw Davies (Emory), and other members of the CCI Center for Selective C-H Functionalization supported by NSF (CHE-1205646).
Accepted Version - nihms499393.pdf
Supplemental Material - ol401514s_si_001.pdf
Supplemental Material - ol401514s_si_002.cif
Supplemental Material - ol401514s_si_003.cif