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At 0 °C, thionyl chloride (3.57 g, 30 mmol) was added dropwise into a solution of 2,4-dibromobenzoicacid (5.60 g, 20 mmol) in methanol (100 mL) slowly. The ice-salt bath used was removed after that dropping and then the reaction mixture was heated to reflux for 3 hours. TLC and LCMS indicated that starting materials reacted completely. The solvent and excess thionyl chloride were removed by rotary evaporation to give a crude product. Then the crude product was dissolved in dichloromethane (100 mL), washed successively with saturated sodium bicarbonate solution (100 mLx2) and saturated brine (100 mL), dried with anhydrous sodium sulfate and filtered. A yellow solid product (5.92 g, 100percent yield) was obtained by rotary evaporation. The molecular ion peak shown by liquid chromatography-mass spectrometry was: MS (ESI): m/z 292.8/294.7/269.9 [M+H]+.
96%
With sulfuric acid; at 0℃;Reflux;
General procedure: The corresponding acid (5 mmol) was dissolved in CH3OH (20 mL), and then H2SO4 (8 equiv) was added at 0 °C, the reaction mixture was then refluxed for 24?48 h. After cooling, the solvent was evaporated. To the resulting mixture was slowly added a solution of 10percent Na2CO3 (200 mL), and then the aqueous solution was extracted with ethyl acetate. The organic layers were combined, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The crude product was purified by column chromatography to obtain compound 3 or compound 4a and 4b.
213.6 g
With sulfuric acid;Reflux;
Step 1: To a 2 L round-bottom flask, 2,4-dibromobenzoicacid (250 g, 0.90 mol) in MeOH (2 L) and concentrated H2SO4 (18.4 g, 0.19 mol) were added. The mixture was refluxed overnight before cooled to room temperature. The resulting precipitate was then filtered, washed with cold methanol and dried under vacuum. It yielded 213.6 g methyl 2,4-dibromobenzoate as a yellow solid. To a 2 L round-bottom flask was added 2,4-dibromobenzoate (200.7 g, 0.69 mol) in 1 L dry DMF. CuCN (123.8 g, 1.38 mol) and NaI (22.8 g, 0.15 mol) were introduced next. The mixture was stirred overnight at 160 °C under nitrogen atmosphere. After the reaction was complete, it was extracted with ethyl acetate (500 mL × 3),washed with water (500 mL) and purified over silica gel (PE/EtOAc = 5/1) to give 93.5 g methyl 2,4-dicyanobenzoate as a brown solid (yield: 72.8 percent).
With lithium aluminium tetrahydride; In tetrahydrofuran; at 0 - 20℃; for 1.0h;
At 0 °C, lithium aluminum hydride (1.14 g, 30 mmol) was dropped into a solution of <strong>[54335-33-0]methyl 2,4-dibromobenzoate</strong> (5.90 g, 20 mmol) in tetrahydrofuran (120 mL) slowly. The ice-salt bath used was removed after that dropping. The reaction was complete (detected with LCMS and TLC) after stirred for 1 hour at room temperature. The mixture was cooled to 0 °C again and the reaction was quenched with water (1.14 mL) and 10percent NaOH solution (11.4 mL) respectively. After stirred for 15 min at room temperature, the mixture was filtered and then the filter cake was washed with tetrahydrofuran (60 mL*2) and ethyl acetate EA (60 mL*2). The filtrate was dried with anhydrous sodium sulfate, filtered, concentrated, and then purified by column chromatography (elution system: petroleum ether: ethyl acetate = 10/1-4/1) to obtain a colorless oil product (2.3 g, 43percent yield). The molecular ion peak shown by liquid chromatography-mass spectrometry was: MS (ESI): m/z 246.9/248.9/250.9 [M-OH]+.
With palladium diacetate; caesium carbonate; 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl; In 1,4-dioxane; at 100℃;Inert atmosphere;
General procedure: To a solution of benzoic acid methyl ester (3, 4a,b) (500 mg), the respective arylamine compounds (2.4 equiv for 3, 1.2 equiv for 4a,b), Cs2CO3 (2.8 equiv for 3, 1.4 equiv for 4a,b), BINAP (0.08 equiv) in 1,4-dioxane (5 mL) was added Pd(OAc)2 (5 mol percent) under nitrogen. And the reaction mixture was stirred at 100 °C for 10?24 h. The reaction mixture was cooled to room temperature, and then H2O was added. The mixture was extracted with ethyl acetate, and then the organic layers were combined, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The crude product was purified by column chromatography.
With palladium diacetate; caesium carbonate; 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl; In 1,4-dioxane; at 100℃;Inert atmosphere;
General procedure: To a solution of benzoic acid methyl ester (3, 4a,b) (500 mg), the respective arylamine compounds (2.4 equiv for 3, 1.2 equiv for 4a,b), Cs2CO3 (2.8 equiv for 3, 1.4 equiv for 4a,b), BINAP (0.08 equiv) in 1,4-dioxane (5 mL) was added Pd(OAc)2 (5 mol percent) under nitrogen. And the reaction mixture was stirred at 100 °C for 10?24 h. The reaction mixture was cooled to room temperature, and then H2O was added. The mixture was extracted with ethyl acetate, and then the organic layers were combined, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The crude product was purified by column chromatography.
With palladium diacetate; caesium carbonate; 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl; In 1,4-dioxane; at 100℃;Inert atmosphere;
General procedure: To a solution of benzoic acid methyl ester (3, 4a,b) (500 mg), the respective arylamine compounds (2.4 equiv for 3, 1.2 equiv for 4a,b), Cs2CO3 (2.8 equiv for 3, 1.4 equiv for 4a,b), BINAP (0.08 equiv) in 1,4-dioxane (5 mL) was added Pd(OAc)2 (5 mol percent) under nitrogen. And the reaction mixture was stirred at 100 °C for 10?24 h. The reaction mixture was cooled to room temperature, and then H2O was added. The mixture was extracted with ethyl acetate, and then the organic layers were combined, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The crude product was purified by column chromatography.
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