tert-butyl 2-bromo-4-fluorobenzoate

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a solution of 2-bromo-4-fluoro-benzoic acid tert-butyl ester (10.0 g, 36 mmol) in THF (100 mL) at −78° C. under an atmosphere of nitrogen was added lithium diisopropylamide (1.8M solution, 20 mL, 36 mmol) dropwise. The reaction mixture was stirred for 1.25 hours before adding DMF (10 mL) then stirred for a further 10 minutes before quenching with acetic acid (3 mL). The products were partitioned between ethyl acetate and water, the organic layer was separated, washed with brine, dried (Na2SO4), filtered and concentrated in vacuo to give a yellow oil which crystallized on standing. The crude product was triturated in cyclohexane to give the title compound as a yellow solid (6.8 g, 62%). 1H NMR (CDCl3, 400 MHz) 10.38 (1H, s), 7.80-7.73 (1H, m), 7.17 (1H, t, J=9.09 Hz), 1.62 (9H, s). then stirred for a further 10 minutes before quenching with acetic acid (3 mL) The products were partitioned between ethyl acetate and water the organic layer was separated washed with brine dried (Na2SO4) filtered concentrated in vacuo to give a yellow oil which crystallized The crude product was triturated in cyclohexane

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a suspension of 2-bromo-4-fluoro-benzoic acid (28.5 g, 0.13 mol) in dichloromethane (500 mL) at room temperature was added oxalyl chloride (11.35 mL, 0.26 mmol) followed by DMF (0.05 mL, catalytic, CARE vigorous gas evolution) and the reaction mixture stirred for 3 hours. The reaction mixture was concentrated in vacuo and the residue dissolved in DCM (500 mL) before treatment with a solution of tert-butanol (28.5 g, 0.26 mol) and pyridine (20.5 g, 0.26 mol). The resultant mixture was stirred at room temperature for 3 days before it was diluted with DCM and washed (1M aqueous sodium hydroxide, water, 0.1M aqueous HCl, water) dried (Na2SO4) filtered and concentrated in vacuo to give a yellow oil. The crude oil was subjected to flash chromatography (Si—PPC, gradient 0 to 20% ethyl acetate in cyclohexane) to give the title compound as a colourless oil (15.2 g, 42%). 1H NMR (CDCl3, 400 MHz) 7.76-7.73 (1H, m), 7.37 (1H, dd, J=8.36, 2.53 Hz), 7.05 (1H, ddd, J=8.70, 7.73, 2.53 Hz), 1.60 (9 H, s). The reaction mixture was concentrated in vacuo washed (1M aqueous sodium hydroxide, water, 0.1M aqueous HCl, water) dried (Na2SO4) filtered concentrated in vacuo to give a yellow oil