Evolution of a Green and Sustainable Manufacturing Process for Belzutifan: Part 3─Development of a Scalable Enzymatic Oxidation Process

Belzutifan (MK-6482) is an FDA-approved hypoxia inducible factor 2α inhibitor for the treatment of Von Hippel–Lindau disease-associated renal cell carcinoma. One of the key synthetic steps is an enzymatic benzylic hydroxylation of an indanone. Prior to optimization, hydroxylation reactions required dilute conditions (100 volumes of water) and high enzyme loading (50 wt %) to achieve the target conversion, which was unsuitable for a long-term manufacturing process. Reduction of reaction volumes introduced additional complexity for large-scale operations due to the low solubility of the reaction components. In addition to reaction development, it was also necessary to find an optimal method of protein residue removal from the reaction mixture to isolate a high-quality product. We present here our efforts to overcome these challenges and ultimately successfully developed, optimized, and demonstrated at a multikilogram scale a process with improved process mass intensity using only a 7.5 wt % enzyme, 25 volumes of water, and 1-octanol as a unique additive.