Efficient synthesis of clascoterone via lipase-catalyzed solvent-free alcoholysis.

Clascoterone (cortexolone 17α-propionate), a novel therapeutic agent for acne, provides enhanced safety and efficacy over conventional therapies. However, the traditional synthesis of clascoterone, especially the final step, suffers from the use of hazardous and excessive organic solvents, along with suboptimal yields due to side reactions and incomplete conversion, which poses environmental and economic challenges. In this study, we developed a regioselective solvent-free alcoholysis method with the commercially available immobilized lipase Novozyme 435 as a catalyst and isopropanol (IPA) as an alcohol donor, achieving a conversion rate of over 98.0 ​% with 20 ​g/L substrate. Furthermore, we implemented a continuous flow microreactor process that increased the conversion rate to 100 ​% with 4 ​g/L substrate, demonstrating scalability for industrial manufacturing.