To a flask fitted with overhead stirrer, condenser, thermometer and nitrogen line was added 3-{[5-(azetidin-1-ylcarbonyl)pyrazin-2-yl]oxy}-5-[(1S)-2-methoxy-1-methylethoxy]benzoic acid (1.0 eq), and acetonitrile (10 vols) followed by pyridine (3 eq) under a nitrogen atmosphere. Thionyl chloride (1.2 eq) as a solution in acetonitrile (0.225 vols) was added slowly, drop-wise via syringe pump over at least 2 hours. 5-Methylpyrazin-2-amine (1.2 eq) was added to the mixture as a solid. After 2.5 hours the reaction was quenched by adding toluene (10 vols) and 1.0M sodium carbonate solution (2.5 eq). The layers were separated. The organic layer was retained in the flask, then 1.0M hydrochloric acid (1.94 eq) was added. The mixture was agitated for 15 minutes then separated. The organic layer was washed with two aliquots of water (5 vols) then the solvent was removed on the rotary evaporator. Toluene (5 vols) was added to the residue, and warmed to 45° C. Isohexane (1.7 vols) was added, the mixture was seeded, and allowed to cool to ambient temperature overnight. The mixture was cooled to 0° C. for 4 hours, and then cooled to −10° C. for 3 hours. The solid was isolated by filtration then washed with iso-hexane (2.5 vols). After drying in the vacuum oven at 40° C. overnight, the desired product was obtained as a solid (corrected yield 85%).
