RDEA 594

Approved by the FDA late in 2015, lesinurad is an urate anion exchange transporter 1 (URAT1) inhibitor for use in the treatment of gout. Ardea Biosciences, which is a subsidiary of AstraZeneca, developed lesinurad to be used in a combination therapy with xanthine oxidase inhibitors for the treatment of hyperuricaemia associated with gout. The approval process is ongoing in several other countries across the globe, with the EMA Committee for Medicinal Products for Human Use giving lesinurad a positive opinion for use as an adjunctive therapy in combination with xanthine oxidase inhibitors to treat hyperuricaemia.

Lesinurad is used to synthesize febuxostat which is a non-purine analog inhibitor of xanthine oxidase. Febuxostat is approved by the European Medicines Agency and the US Food and Drug Administration for treating gout.

ChEBI: A member of the class of triazoles that is [(3-bromo-1,2,4-triazol-5-yl)sulfanyl]acetic acid substituted at position 1 of the triazole ring by a 4-cyclopropylnaphthalen-1-yl group. Used for treatment of gout.

The synthesis of lesinurad began with commercial 1- bromonaphthalene (138). A Kumada coupling between this bromide and cyclopropyl Grignard delivered 139, which after selective nitration to give 140, delivered the oxylate salt 141 (which now is commercially available). Treatment of 141 with KOH followed by thiophosgene at 5 ??C delivered isothiocyanate 142 in 63% yield. Reaction of 142 with formyl hydrazine followed by addition of potassium bicarbonate and mild heating resulted in thio-1,2,4-triazole 144 by the intermediacy of 143. Quantitative alkylation of triazolothiol 144 resulted in |á-mercaptan 145, and this was followed by NBS bromination to afford bromotriazole 146. Ester saponification followed by acidification secured lesinurad (XVII) in a good yield over the final three steps.