tert-Butyl 4-[4-[5-[bis(tert-butoxycarbonyl)amino]-6-[5-(3-methyl-2-thienyl)-1,3,4-oxadiazol-2-yl]pyrazin-2-yl]-3-cyano-benzoyl]-1,4-diazepane-1-carboxylate (9.9 g, 11.32 mmol) was dissolved in anhydrous CH2Cl2 (100 mL) at room temperature and TFA (10 mL, 129.8 mmol) added. Additional TFA (10 mL, 129.8 mmol) was added and the reaction mixture stirred at room temperature for 3.5 h and then concentrated in vacuo. The material was dissolved in a mixture of acetonitrile and methanol (10; 1 mixture) and PS—HCO3 (5 eq) added. The mixture was stirred for 1 h at room temperature and then the resin removed by filtration and washed with acetonitrile and methanol. The filtrate was concentrated in vacuo and the residue recrystallised from acetonitrile. The isolated solid was washed with ether and dried to give the product as a yellow solid (2.41 g, 35% yield); 1H NMR (400 MHz, DMSO) d 1.76-1.84 (m, 2H), 2.67 (s, 3H), 2.88-2.93 (m, 4H), 3.42-3.44 (m, 2H), 3.67-3.74 (m, 2H), 7.2 (d, 1H), 7.84-7.87 (m, 1H), 7.89-7.99 (m, 1H), 8.04-8.09 (m, 2H) and 8.85 (s, 1H) ppm; MS (ES+) 487.26
