A solution of tert-butyl N-(4-[[(12R)-12-(carbamoylmethyl)-8-thia-4,6-diazatricyclo[7.4.0.0[2,7]]trideca-1(9),2(7),3,5-tetraen-3-yl]oxy]cyclohexyl)carbamate (72 mg, 0.16 mmol, 1.00 equiv) in 5 mL of dichloromethane (5 mL) was added 6 M aqueous hydrochloric acid (0.5 mL) at 0° C. and the resulting solution was stirred overnight at room temperature. The resulting mixture was concentrated under vacuum to give 62 mg (crude) of 2-[(12R)-3-[(4-aminocyclohexyl)oxy]-8-thia-4,6-diazatricyclo[7.4.0.0[2,7]]trideca-1(9),2(7),3,5-tetraen-12-yl]acetamide hydrochloride as a yellow solid. The crude hydrochloride in 4 mL of MeOH was added HCHO (37%, 1 mL) and 0.5 mL of HOAc at room temperature. Then NaCNBH3 (31 mg, 0.49 mmol, 2.54 equiv) was added and the resulting solution was stirred for 4 h at ambient temperature. The resulting mixture was filtered through a thin silica column and further purified by preparative HPLC under the following conditions (Waters): column: Xbridge Prep C18 5 um, 19*150 mm; mobile phase: water with 0.05% NH4HCO3 and CH3CN (5.0% CH3CN up to 41.0% in 9 min, up to 95.0% in 2 min, down to 5.0% in 2 min); flow rate: 20 mL/min; UV detection at 220/254 nm. The product-containing fractions were collected and evaporated under reduced pressure to give the desired 2-[(12R)-3-[[4-(dimethylamino)cyclohexyl]oxy]-8-thia-4,6-diazatricyclo[7.4.0.0[2,7]]trideca-1(9),2(7),3,5-tetraen-12-yl]acetamide (13.8 mg) as a white solid. MS: 389 (M+H)+. 1H NMR (300 MHz, CDCl3): δ 8.51 (s, 1H), 5.46-5.40 (m, 1H), 5.24-5.21 (m, 1H), 3.30-3.24 (m, 1H), 2.91 (m, 2H), 2.62-2.59 (m, 1H), 2.56-2.32 (m, 11H), 2.15-2.11 (m, 1H), 2.02-2.00 (m, 3H), 1.74-1.49 (m, 6H).
