To a solution of (1S,2R)-5′-(4-chlorophenyl)-2-(methoxymethyl)-6′,7′-dimethylspiro-[cyclopropane-1,3′-thieno[2,3-e][1,4]diazepin]-2′(1′H)-one (3.7, 9.87 mmol) in anhydrous THF (200 mL) at −78° C. was slowly added a solution of potassium tert-butoxide (12.34 mL, 12.34 mmol). The resulting dark brown solution was warmed to rt and stirred for 30 min. The reaction was cooled to −78° C. before diethyl phosphorochloridate (2.85 mL, 19.74 mmol) was slowly added. Once the addition was completed, the reaction was warmed to rt for 60 to 90 min before acetohydrazide (2.193 mg, 29.6 mmol) was added. The reaction was then heated to 60° C. for 2 h before MeOH (5 mL) and silica gel were sequentially added. The solvent was removed under vacuum, the dry silica gel was packed, and the product was purified by flash chromatography (EtOAc/hexane 3:7 to 100:0) to give (1S,2R)-4′-(4-chlorophenyl)-2-(methoxymethyl)-2′,3′,9′-trimethylspiro[cyclopropane-1,6′-thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine] as a solid (3.54 g). LRMS (M+H)+: 413 m/z. 1H NMR (two conformers detected in ˜1:1 ratio) (400 MHz, DMSO-d6) δ 7.42-7.55 (m, 4H), 3.82 (dd, J=7.32, 10.99 Hz, 0.5H), 3.71 (dd, J=6.41, 11.22 Hz, 0.5H), 3.39 (s, 1.5H), 3.21 (dd, J=6.29, 10.87 Hz, 0.5H), 3.04 (dd, J=7.67, 10.87 Hz, 0.5H), 2.97 (s, 1.5H), 2.60 (s, 3H), 2.39 (s, 1.5H), 2.38 (s, 1.5H), 2.16-2.27 (m, 0.5H), 2.05 (dd, J=5.26, 9.38 Hz, 0.5H), 1.58 (s, 1.5H), 1.54 (s, 1.5H), 1.43-1.51 (m, 0.5H), 1.33-1.40 (m, 0.5H), 1.03 (dd, J=5.38, 9.27 Hz, 0.5H), 0.61 (t, J=6.07 Hz, 0.5H).
