Cesium carbonate → tert-Butyl 4-(1-ethyl-2-oxo-7-phenyl-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazin-6-yl)benzylcarbamate

Participants

Reaction Conditions

Reaction Steps

In a 15 mL reaction tube was added 6-bromo-1-ethyl-7-phenyl-1H-pyrido[2,3-b][1,4]oxazin-2(3H)-one (50 mg, 0.150 mmol), tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzylcarbamate (60.0 mg, 0.180 mmol), and CESIUM CARBONATE (244 mg, 0.750 mmol) in a mixture of 1,4-Dioxane (2814 μl) and water (938 μl) to give a colourless solution. This was degassed by bubbling nitrogen for 15 minutes, followed by the addition of PdCl2(dppf)-CH2Cl2Adduct (24.51 mg, 0.030 mmol) and degassing for a further 5 minutes. The reaction mixture was heated to 50° C. under a nitrogen atmosphere for one hour. LC-MS analysis showed reaction completion. The reaction mixture was allowed to cool to room temperature, diluted with water (5 mL) and extracted into ethyl acetate (3×5 mL). The combined organic phases were dried over Na2SO4, filtered and concentrated to dryness under reduced pressure to give an off-white solid. The resulting residue was purified via Biotage (15-85% cyclohexane:EtOAc; 10 g column) to give the title compound (45 mg, 65.3%) as off-white solid. 1H NMR (500 MHz, CDCl3): 7.31-7.27 (6H, m), 7.19-7.18 (2H, d), 7.11-7.10 (2H, d), 4.87 (2H, s), 4.84 (1H, br), 4.27 (2H, s), 4.03-3.98 (2H, q), 1.45 (9H, br), 1.32-1.30 (3H, t).

Provenance & Evidence