Unified Enantioselective, Convergent Synthetic Approach Toward the Furanobutenolide-Derived Polycyclic Norcembranoid Diterpenes: Synthesis of a Series of Ineleganoloids by Oxidation State Manipulation of the Carbocyclic Core
Late-stage synthetic efforts to advance the enatio- and diastereoselectively constructed [6,7,5,5]-fused tetracyclic scaffold toward the polycyclic norditerpenoid ineleganolide are disclosed. The described investigations focus on oxidation-state manipulation around the central cycloheptane ring. Computational evaluation of ground-state energies of dihydroineleganolide is used to rationalize empirical observations and provide insight for further synthetic development, enhancing the understanding of the conformational constraints of these compact polycyclic structures. Advanced synthetic manipulations generated a series of natural product-like compounds termed the ineleganoloids.
Additional Information© 2019 American Chemical Society. Received: March 4, 2019; Published: May 8, 2019. The authors wish to thank the NIH-NIGMS (R01GM080269), Amgen, the Gordon and Betty Moore Foundation, and Caltech for financial support and Eli Lilly & Co. for assistance with biological activity screening. Additionally, the authors gratefully acknowledge Larry Henling and Dr. Michael Takase (Caltech) for X-ray crystallographic structural determination, Dr. Mona Shahgholi and Naseem Torian (Caltech) for mass spectrometry assistance, and Dr. David VanderVelde (Caltech) for NMR experimental assistance and helpful discussion. Additionally, Dr. Jeffrey C. Holder, Dr. Corey M. Reeves, Prof. Hosea M. Nelson, Dr. Jonny R. Gordon, Dr. Pamela M. Tadross, and Beau P. Pritchett (Caltech) are thanked helpful discussion. R.A.C. gratefully acknowledges the support of this work provided by a fellowship from the National Cancer Institute of the National Institutes of Health (NIH) under Award Number F31A17435. J.L.R. thanks the California Tobacco-Related Disease Research Program of the University of California, Grant Number 14DT-0004 for a predoctoral fellowship. A.C.J. thanks the NIH for the support of this work provided by a postdoctoral fellowship (award number F32GM082000). The authors declare no competing financial interest.
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