Chemical Synthesis of Polygalacic Acid from Oleanolic Acid Enabled by Three Site-Selective C-H Oxidations.

Abstract

The first chemical synthesis of polygalacic acid was accomplished from readily available oleanolic acid through three complementary site-selective C-H oxidation reactions. Key transformations include palladium-catalyzed directed C-23 oxidation, base-promoted C-2 α-oxidation, and copper-mediated directed C-16 hydroxylation, enabling selective installation of three oxygen functionalities onto the pentacyclic triterpenoid scaffold. This work demonstrates an oxidation-based strategy for converting an abundant triterpenoid into a more highly oxygenated natural product.

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