A solution of 2,2-dimethyl-1-propanol (9 mg, 0.10 mmol) in dry tetrahydrofuran (1 mL) is cooled at −78° C. and treated with sodium hydride (60% in mineral oil, 5 mg, 0.11 mmol). After 20 min, a solution of 4-nitrophenyl 4-(4-cyanophenyl)-2,5-dioxo-1-(3-(trifluoromethyl)phenyl)-1,2,5,6,7,8-hexahydroquinazoline-3(4H)-carboxylate (intermediate 37, 60 mg, 0.10 mmol) in tetrahydrofuran (1 mL) is added and the mixture is stirred for 5 h at room temperature. Another portion of 2,2-dimethyl-1-propanol (9 mg, 0.10 mmol) is added and the mixture is stirred over night. Another portion of 2,2-dimethyl-1-propanol (18 mg, 0.20 mmol) is added and the mixture is heated at 50° C. for 2 h. Water is added and the mixture is extracted with dichlormethane. The organic layer is concentrated under reduced it) pressure and the residue is purified by flash chromatography on silica (gradient cyclohexane to cyclohexane/ethyl acetate 1:1). Yield: 12 mg; ESI mass spectrum [M+H]+=526; Retention time HPLC: 0.76 min (X012_S01).
