Methyl 4-[5-[3-amino-6-[4-(dimethylcarbamoyl)phenyl]pyrazin-2-yl]-1,3,4-oxadiazol-2-yl]benzoate (154 mg, 0.3465 mmol) in dry THF (1.5 mL) was cooled in ice-bath then treated dropwise with DIBAL (346.5 μL of 1 M solution in hexanes, 0.3465 mmol). The resulting mixture was stirred 0-20° C. over 90 min and then at room temperature overnight. Additional DIBAL (1.732 mL of 1 M solution in hexanes, 1.732 mmol) was added at room temperature. The reaction mixture was poured onto water (10 mL) and acidified with 2M HCl, adjusted to pH 10 with aq NaOH solution and extracted EtOAc (6×10 mL) to give an orange solid. This was purified by reverse phase preparative HPLC [Waters Sunfire C18, 10 μM, 100 Å column, gradient 10%-95% B (solvent A: 0.05% TFA in water; solvent B: CH3CN) over 16 minutes at 25 mL/min]. Product fractions were combined and passed through a bicarbonate cartridge. The eluent was concentrated in vacuo and taken up in acetonitrile and water and lypholised to leave the product as a yellow powder (13.1 mg, 33% yield); 1H NMR (400 MHz, DMSO) d 2.18 (s, 6H), 4.64 (s, 2H), 5.43 (br s, 1H), 4.43-4.45 (m, 2H), 7.65-7.63 (m, 2H), 7.69 (br s, 2H), 8.05-8.30 (m, 4H) and 8.92 (s, 1H) ppm; MS (ES+) 403.18
