Реакция #10791

Уравнение реакции

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

Выход 40.0%

Растворители

water

Условия реакции

Обработка

1. 1
   workup.ADDITIONwas added
2. 2
   Другоеdegassed tetrahydrofuran (15 mL)
3. 3
   ДругоеThe reaction was then quenched by water
4. 4
   ЭкстракцияThe aqueous solution was extracted with ethyl acetate
5. 5
   ПромывкаThe solution of ethyl acetate was washed with saturated solution of sodium bicarbonate, brine
6. 6
   Сушкаdried over sodium sulfate
7. 7
   Концентрированиеconcentrated
8. 8
   ДругоеThe crude product was purified by flash chromatography
9. 9
   ПромывкаElution with ethyl acetate (50%, v/v, in hexane)

Методика

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%).

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