تفاعل #10791

معادلة التفاعل

2,4-dimethoxy-5-bromo-benzaldehye

4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyrazole-1-carboxylic acid tert-butyl ester

potassium fluoride

potassium fluoride

→

4-(5-formyl-2,4-dimethoxy-phenyl)-pyrazole-1-carboxylic acid tert-butyl ester

المردود 40.0%

المذيبات

water

ظروف التفاعل

المعالجة

1. 1
   workup.ADDITIONwas added
2. 2
   أخرىdegassed tetrahydrofuran (15 mL)
3. 3
   أخرىThe reaction was then quenched by water
4. 4
   استخلاصThe aqueous solution was extracted with ethyl acetate
5. 5
   غسيلThe solution of ethyl acetate was washed with saturated solution of sodium bicarbonate, brine
6. 6
   تجفيفdried over sodium sulfate
7. 7
   تركيزconcentrated
8. 8
   أخرىThe crude product was purified by flash chromatography
9. 9
   غسيلElution with ethyl acetate (50%, v/v, in hexane)

الإجراء التجريبي

Ex-74B: To a mixture of 2,4-dimethoxy-5-bromo-benzaldehye (0.28 g, 1.13 mmol), 4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyrazole-1-carboxylic acid tert-butyl ester (Ex-76A, 0.61 g, 1.70 mmol), bis(tri-tert-butylphosphine)palladium (43 mg, 0.085 mmol) and potassium fluoride (0.24 g, 4.08 mmol) was added degassed tetrahydrofuran (15 mL). The reaction mixture was heated at 60° C. for one day. Additional potassium fluoride (0.24 g, 4.08 mmol) and water (20 μL) were added. The reaction mixture continued to stir at 60° C. for another 8 hours. The reaction was then quenched by water. The aqueous solution was extracted with ethyl acetate. The solution of ethyl acetate was washed with saturated solution of sodium bicarbonate, brine, dried over sodium sulfate and concentrated. The crude product was purified by flash chromatography. Elution with ethyl acetate (50%, v/v, in hexane) afforded 4-(5-formyl-2,4-dimethoxy-phenyl)-pyrazole-1-carboxylic acid tert-butyl ester (0.15 g, 40%) as white solid. 1H NMR (CDCl3) δ 10.35 (s, 1H), 8.43 (s, 1H), 8.09 (s, 1H), 8.02 (s, 1H), 6.52 (s, 1H), 4.02 (s, 3H), 3.99 (s, 3H), 1.68 (s, 9H). MS m/z=333 ([M+H]+, 100%).

المصدر