* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
10.0 g (37.1 mmol) of 4,5-dibromofuran-2-carboxylic acid are provided in an aqueous ammonia solution (7.3percent) and cooled to 0° C. With vigorous stirring, 2.54 g (38.9 mmol) of zinc powder are added in portions such that the temperature does not exceed 7° C. The mixture is stirred at 0° C. for 10 minutes and an acidic pH is then established by the addition of an aqueous HCl solution. The suspension is extracted with ethyl acetate and the organic phase is dried over sodium sulfate, filtered and concentrated. 7.27 g (99percent of theory) of the title compound are obtained.1H-NMR (400 MHz, DMSO-d6): δ=13.5 (s, 1H), 8.17 (s, 1H), 7.40 (s, 1H).LC-MS (Method 1): Rt=1.52 min; MS (ESIpos): m/z=191 [M+H]+.
83.1%
Stage #1: With ammonium hydroxide; zinc In water at 20℃; for 6 h; Stage #2: With hydrogenchloride In water
Step 1 4-Bromo-furan-2-carboxylic acid A mixture of 4,5-dibromo-furan-2-carboxylic acid; 28a (5.5 g, 20.3 mmol) and 18 mL of ammonium hydroxide was added to 63 mL of water followed by addition of zinc powder (1.46 g, 22.33 mmol). Upon completion of the addition, the reaction mixture was stirred at room temperature for 6 hours. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was adjusted to pH 3 with hydrochloric acid (1 N) to form a copious amount of precipitates. The mixture was filtered and the filter cake was washed with n-hexane (15 mL.x.4) and dried to obtain the title compound 4-bromo-furan-2-carboxylic acid 28b (3.2 g, yield 83.1 percent) as a white solid. MS m/z (ESI): 188.7 [M-1]
83.1%
Stage #1: at 20℃; for 6 h; Stage #2: With hydrogenchloride In water
Example 22: (Z)-4-(2-Hydroxy-3-{N'-[3-methyl-5-oxo-1-(5,6,7,8-tetrahydro-naphthal-2-yl)-1,5-di-hydro- pyrazol-4-ylidene]-hydrazino}-phenyl)-furan-2-carboxylic acid bis-(ethanolamine); Step 1; 4-Bromo-furan-2-carboxylic acid; A mixture of 4,5-dibromo-furan-2-carboxylic acid 22a (5.5 g, 20.3 mmol) and 18 mL of ammonium hydroxide was added to 63 mL of water followed by addition of zinc powder (1.46 g, 22.33 mmol). Upon completion of the addition, the reaction mixture was stirred at room temperature for 6 hours. The mixture was adjusted to pH 3 with 1 M hydrochloric acid to form a great quantity of precipitates. The mixture was filtered and the filter cake was washed with n-hexane (15 mLx4) and dried to obtain the title compound 4-bromo-furan-2-carboxylic acid 22b (3.2 g, yield 83.1 percent) as a white solid. MS m/z (ESI): 188.7 [M-1]
83.1%
With ammonium hydroxide; zinc In water at 20℃; for 6 h;
At room temperature, 4,5-dibromofuran-2-carboxylic acid 22a (5.5g, 20.30 mmol), 18mL of aqueous ammonia in 63mL water, and zinc powder (1.46g, 22.33 mmol) were mixed. After addition was complete, it was stirred at room temperature for 6 hours. The reaction solution was adjusted pH = 3 with 1M hydrochloric acid. The solid precipitate was filtered. The filter cake was washed with n-hexane (15mL × 4) and dried to give the title product 4-bromofuran-2-carboxylic acid 22b (3.2g, white solid), yield: 83.1percent.
46%
Stage #1: at 0 - 7℃; for 1 h; Stage #2: at 20℃;
Step C: 4-Bromo-2-furoic acid. 4,5-Dibromo-2-furoic acid (24.51 g, 90.8 mmol) was dissolved in a mixture of water (280 mL) and aq. NH4OH (33percent NH3; 80 mL) and <n="20"/>cooled in an ice bath. The mixture was stirred rapidly as zinc dust (6.23 g, 95.3 mmol) was added in portions while keeping the internal temperature below 7 0C. The mixture was stirred at 0 0C for 30 min. An additional portion of zinc dust (0.5 g, 7.6 mmol) was added and the mixture was allowed to stir at 0 0C for 30 min. The reaction was acidified to pH 1 with cone. HCI causing precipitation of the product. The mixture was cooled to 10 0C, and the product was collected by suction filtration, washed with water, and air dried to provide 8.0 g (46percent) of the desired acid. Additional product could be obtained by extraction of the filtrate with DCM and recrystallization of the crude extract from water. 1H NMR (CDCI3): 7.76 (d, J = 0.8, 1 H), 7.14 (d, J = 0.8, 1 H).
46%
With ammonia; zinc In water at 0 - 7℃; for 1 h;
C. 4-Bromo-2-furoic acid. ; 4,5-Dibromo-2-furoic acid (24.51 g, 90.8 mmol) was dissolved in a mixture of water (280 mL) and aq. NH4OH (33percent NH3; 80 mL) and cooled in an ice bath. The mixture was stirred rapidly as zinc dust (6.23 g, 95.3 mmol) was added in portions while keeping the internal temperature below 7° C. The mixture was stirred at 0° C. for 30 min. HPLC analysis of an aliquot of the reaction mixture indicated some starting material remaining. An additional portion of zinc dust (0.5 g, 7.6 mmol) was added and the mixture was stirred at 0° C. for 30 min. HPLC analysis of an aliquot indicated only a trace of starting material as well as formation of a small amount of 2-furoic acid from over-reduction. The mixture was acidified to pH 1 with conc. HCl causing precipitation of the product. The mixture was cooled to 10° C., and the product was collected by suction filtration, washed with water, and air dried to provide 8.0 g (46percent) of the desired acid. Additional product could be obtained by extraction of the filtrate with DCM and recrystallization of the crude extract from water. 1H NMR (400 MHz, CDCl3): 7.76 (d, J=0.8, 1H), 7.14 (d, J=0.8, 1H).
665 mg
With ammonium hydroxide; zinc In water at 20℃; for 3 h;
4,5-Dibromofuran-2-carboxylic acid (9, 1.00 g, 3.7 mmol) was suspended in water (11 mL) and NH4OH (3.5 mL) with vigorous stirring at ambient temperature. Powdered zinc metal (1.30 g, 20.3 mmol) was added, and the mixture was allowed to stir at ambient temperature for 3 h. The reaction mixture was filtered through a pad of Celite and acidified (pH 2) with 2 N HCl. The filtrate was extracted with EtOAc (4 * 50 mL), dried (Na2SO4), and concentrated to dryness under reduced pressure to provide 665 mg of a white powder. To this crude intermediate dissolved in MeOH (12 mL) was added concentrated sulfuric acid (80 μL) while stirring. The resulting solution was heated to reflux and stirred overnight. The reaction mixture was allowed to cool to room temperature followed by concentration under vacuum. The resulting crude residue was then partitioned between saturated aqueous NaHCO3 and diethyl ether, and the aqueous layer was further extracted with diethyl ether (2 * 40 mL). The combined ether solutions were washed with brine (20 mL), dried (Na2SO4) and concentrated to dryness under reduced pressure to provide 652 mg (3.18 mmol, 86percent) of the desired product as a clear oil.
Chemistry
Pharmaceutical Intermediates
Inhibitors/Agonists
Material Science
For Research Only
120K+ Compounds
Competitive Price
1-2 Day Shipping
