Studies on the Synthesis Process of Plant-Derived Ursodeoxycholic Acid Intermediates.

Ursodeoxycholic acid (UDCA), a critical secondary bile acid in human physiology, demonstrates significant industrial potential through synthetic routes from bisnoralcohol (BA). Current synthetic routes rely on hydroxyl oxidation and Horner-Wadsworth-Emmons reactions as critical initial steps, facing unresolved challenges in reaction scale-up dynamics and impurity evolution. In this work, we systematically investigated the scale-up effects and innovatively addressed the impurity control problem. In the OH-C(22) selective oxidation of BA, the impurity C(22) carboxylic acid was synthesized, the emulsification was eliminated by process optimization, and the yield was increased from 89.0% to 95.2%. In the Horner-Wadsworth-Emmons reaction, the C(20)-methyl racemate and the C(22)-Z-ene isomer were synthesized, followed by the validation of the remaining byproducts. Based on impurity profile analysis, we innovatively modified the reaction feeding protocol, increased the yield from 79.1% to 90.8%, and significantly improved reaction selectivity. This optimized process demonstrates superior scalability and provides valuable insights for the industrial production of plant-derived UDCA.