Cesium carbonate → Methyl 4-methyl-4'-nitrobiphenyl-3-carboxylate

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The compound of example 2 (0.592 g, 0.0026 mol, 1.0 eq), bis(pinacolato)diboron (0.711 g, 0.0028 mol, 1.05 eq), palladium acetate (17.4 mg, 0.0007 mol, 3 mol % eq) and potassium acetate (0.765 g, 0.0078 mol, 3 eq) were taken in 10 mL of dry DMF. The mixture was degassed by gently bubbling argon through it for 30 min at room temperature. The mixture was then heated at 80° C. under argon atmosphere until completion of reaction (3 h). After completion of reaction, the reaction mixture was cooled to room temperature, followed by addition of 1-bromo-4-nitrobenzene (0.52 g, 0.0026 mol, 1.0 eq), cesium carbonate (1.27 g, 0.00039 mol, 1.5 eq) and Pd(PPh3)4 (0.090 g, 0.078 mol, 3 mol %). The reaction mixture was then heated at 80° C. for about 16 h under argon, then cooled to room temperature and diluted with water (20 mL) and ethyl acetate (20 mL). Black particles were removed by passing through a pad of celite. The organic layer was separated and washed twice with 15 mL of brine solution. After drying over anhydrous sodium sulfate, the solvent was removed to give crude 2-(4′-nitro-biphenyl-4-methyl)methyl benzoate, which was purified by column chromatography (silicagel, 1-5% ethyl acetate in petroleum ether) to obtain the title compound.

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