Synthesis of the Pentacyclic Core of Sanguinone B Enabled by Alkyne Functionalization
Jonathan Farhi1, Samir P Rezgui1, Hao Yu1
1The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Abstract:
Sanguinones A and B are recently isolated pyrroloiminoquinone alkaloids possessing a rare C4 carboxylic acid. We report a synthetic approach toward the full carbon and nitrogen pentacyclic core of sanguinone B, with the correct oxidation at C4. Highlights of this approach include the application of a Larock/Buchwald-Hartwig annulation cascade to access a key tricyclic intermediate and alkyne functionalization using Rh(I) or Cu(I) catalysis to access hindered benzylic ketones.
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