Reaction Steps
To a mixture of 3-(5-(tert-butyl)-1,3,4-oxadiazol-2-yl)-5-(1-ethyl-3-(piperidin-4-yl)-1H-1,2,4-triazol-5-yl)pyrazin-2-amine (257 mg, 0.50 mmol, TFA salt), potassium (S)-2,2-dimethyl-1,3-dioxolane-4-carboxylate (101 mg, 0.55 mmol) and EDCI (105 mg, 0.55 mmol) in DCM (5 mL) were added 1-hydroxy-1H-benzotriazol hydrate (85 mg, 0.56 mmol) and DIPEA (194 mg, 1.50 mmol). The mixture was stirred for 16 hours at room temperature. Water was added to the mixture and the mixture was extracted with DCM. The organic layers were washed with brine and dried over Na2SO4, filtered and concentrated to give (S)-(4-(5-(5-amino-6-(5-(tert-butyl)-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)-1-ethyl-1H-1,2,4-triazol-3-yl)piperidin-1-yl)(2,2-dimethyl-1,3-dioxolan-4-yl)methanone (320 mg). Mass Spectrum [M+H]+=526. To a mixture of (S)-(4-(5-(5-amino-6-(5-(tert-butyl)-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)-1-ethyl-1H-1,2,4-triazol-3-yl)piperidin-1-yl)(2,2-dimethyl-1,3-dioxolan-4-yl)methanone (320 mg) in DCM (10 mL) at r.t was added dropwise TFA (1.6 ml, 20.77 mmol). The mixture was stirred for 16 h at r.t, concentrated and purified by preparative HPLC (Waters XBridge Prep C18 OBD column, 5μ silica, 19 mm diameter, 100 mm length) using decreasingly polar mixtures of water (containing 0.1% NH3) and MeCN as the eluant. The fractions containing the desired compound were evaporated to dryness to afford the title compound (142 mg, 48%) as a white solid. 1H NMR Spectrum (400 Hz, DMSO-d6, 30° C.): 1.45 (12H, m), 1.56 (1H, m), 1.70 (1H, m), 1.98 (2H, m), 2.85 (1H, m), 3.00 (1H, m), 3.20 (1H, m), 3.45 (1H, s), 3.55 (1H, s), 4.05 (1H, m), 4.35 (2H, m), 4.60 (2H, m), 4.70 (1H, m), 4.85 (1H, m), 7.90 (2H, m), 8.85 (1H, s); Mass Spectrum [M+H]+=486.
