Total Synthesis of Platycaryanin A

Platycaryanin A, a structurally complex ellagitannin bearing a rare tergalloyl moiety, has eluded chemical synthesis to date. Herein, we report the first total synthesis of platycaryanin A, addressing key challenges in the regio- and stereoselective construction of its trimeric gallic acid framework. Direct oxidative coupling of galloyl and isodehydrodigalloyl units proved unsuccessful, highlighting the inherent difficulty of regio- and stereoselective assembly. A bioinspired oxa-Michael addition of an isodehydrodigallic acid derivative enabled the efficient formation of the tergalloyl group, followed by strategic functional-group manipulations to deliver platycaryanin A in its natural form. This work establishes a general approach to the synthesis of complex polyphenolic natural products.