Dimethylformamide dimethyl acetal → methyl 2-(1-isopropyl-1H-1,2,4-triazol-5-yl)-5,6-dihydrobenzo[f]imidazo[1,2-d][1,4]oxazepine-9-carboxylate

Alternatively, methyl 2-carbamoyl-5,6-dihydrobenzo[f]imidazo[1,2-d][1,4]oxazepine-9-carboxylate (370 mg, 1.3 mmol) in dimethoxyethane (3 mL) was treated with 1,1-dimethoxy-N,N-dimethylmethanamine (1 mL, 7.5 mmol) and heated to 90° C. for 0.5 h. LC/MS indicated major desired product. After cooling, the reaction was concentrated to give the crude acylamidine and then suspended in acetic acid (2.3 mL), treated with isopropylhydrazine hydrochloride (0.29 g, 2.5 mmol). The mixture was heated at 75° C. for 30 min., cooled to room temperature and concentrated. Purification by ISCO using 100% EtOAc gave 184 (0.32 g, 70% yield). 1H NMR (400 MHz, DMSO) δ 8.54 (d, J=8.4, 1H), 8.02 (s, 1H), 7.93 (s, 1H), 7.70 (dd, J=8.4, 1.7, 1H), 7.57 (d, J=1.7, 1H), 5.85 (dq, J=13.3, 6.6, 1H), 4.57 (q, J=6.0, 4H), 3.87 (s, 3H), 1.49 (d, J=6.6, 6H).