A Concise semisynthesis of hederagonic acid: c–h activation in natural product synthesis

Christian Knittl-Frank reports on the development of a novel synthetic route to the naturally occurring polyhydroxylated oleanane, hederagonic acid. Polyhydroxylated oleananes are a vast family of naturally occurring triterpenoids with versatile biological activities. A low commercial availability combined with high prices make these molecules interesting targets in natural product synthesis. The developed synthetic approach starts from oleanolic acid, a cheap material that is commercially available in bulk quantities. It features several multi-step one-pot reactions, allowing a minimization of the number of steps and reducing the preparative effort. Importantly, catalytic C–H functionalization was achieved at unusually low temperatures. Hederagonic acid was thus prepared in as little as four steps, resulting in the shortest semisynthesis of this oleanane to date. Contents Hederagonic Acid and C−H Activation; Optimization of the Synthetic Sequence Final Synthetic Route to Hederagonic Acid Experimental Section Target Groups Scientists and students in the field of organic chemistry, especially natural product synthesis The Author Christian Knittl-Frank is currently pursuing his PhD studies, focusing on natural product synthesis and synthetic methodology, at the Department of Organic Chemistry, University of Vienna, Austria. He is part of the MolTag doctoral program that aims to development new molecular drugs targeting ion channels. .