Early Process Development of an LPAR1 Antagonist, GS-2278

(R)-1-(2,5-Difluoropyridin-3-yl)ethyl(1-methyl-4-(5-(2-(trifluoromethyl)pyrimidine-5-carboxamido)pyridin-2-yl)-1H-1,2,3-triazol-5-yl)carbamate (GS-2278) is a lysophosphatidic acid receptor 1 antagonist under development for the treatment of idiopathic pulmonary fibrosis. GS-2278 is assembled in a 9-step sequence. Initially, 2-bromo-5-fluoropyridine is metalated and trapped with ethyl difluoroacetate. Then, after condensation with tosyl hydrazide, Sakai cyclization with methylamine, and carboxylation with carbon dioxide, the triazole carboxylic acid core is generated. For the final assembly, the core is elaborated through a two-step hydroxamic acid formation and Lossen rearrangement to form an isocyanate which is trapped in situ by a chiral alcohol. The resulting carbamate is Boc-deprotected and subjected to amide coupling with a pyrimidine carboxylic acid to yield the active pharmaceutical ingredient. Process development was conducted to determine reaction and isolation conditions to enable scale-ups to support preclinical and early clinical studies. This paper focuses on the development of conditions from the medicinal chemistry route to the Ph 1 manufacturing route.