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With bromine; potassium carbonate; In dichloromethane; acetonitrile; at 20℃; for 12.0h;
a) dimethyl 2-bromo-1H-imidazole-4,5-dicarboxylate 9.50 g bromine in 100 ml dichloromethane are added dropwise to a mixture of 9.90 g methyl 1H-imidazole-4,5-dicarboxylate and 7.46 g potassium carbonate in 200 ml dichloromethane and 80 ml acetonitrile. The mixture is stirred for 12 h at ambient temperature in the dark and then added to a saturated aqueous solution of sodium thiosulphate and sodium chloride. The organic phase is separated off and the aqueous phase is extracted several times with ethyl acetate. The combined organic phases are dried over sodium sulphate and the solvent is removed. Yield: 12.31 g (87% of theory) Mass spectrum (ESI+): m/z=263/265 (Br) [M+H]+
87%
With bromine; potassium carbonate; In dichloromethane; acetonitrile; at 20℃; for 2.0h;
At ambient temperature 9.50 g (59.45 mmol) bromine were added dropwise to a solution of 9.90 g (53.76 mmol) dimethyl imidazole-4,5-dicarboxylate in 300 ml dichloromethane and 80 ml acetonitrile. 7.46 g (54.00 mmol) potassium carbonate was added, and the reaction mixture was stirred for 2 hours at ambient temperature. Then the dichloromethane was eliminated using the rotary evaporator and the residue was combined with a saturated solution of sodium chloride and sodium thiosulphate. It was extracted ten times with ethyl acetate, the organic extracts were dried over sodium sulphate and then the solvent was eliminated. Yield: 12.31 g (87% of theory) C7H7BrN2O4 (263.05) Mass spectrum: (M+H)+=263/265 (bromine)
46%
With bromine; potassium carbonate; In dichloromethane; at 20℃; for 1.0h;
EXAMPLE VI Dimethyl 2-bromo-1H-imidazole-4.5-dicarboxylate 6.11 ml bromine are added to 19.80 g dimethyl 1H-imidazole4,5-dicarboxylate and 14.92 g potassium carbonate in 600 ml methylene chloride. The reaction mixture is stirred for one hour at ambient temperature, then a mixture of saturated sodium sulphite solution and saturated sodium chloride solution (1:1) is added. The organic phase is largely separated off and the aqueous phase is extracted with ethyl acetate several times. The combined organic phases are dried over magnesium sulphate and evaporated down, leaving about 7.40 g crude product. The aqueous phase is combined with ethyl acetate and extracted overnight in an extraction apparatus. The ethyl acetate extract is evaporated down and the flask residue is combined with the crude product already obtained. Yield: 13.10 g (46% of theory) Mass spectrum (ESI+): m/z=263, 265 [M+H]+
With bromine; potassium carbonate; In dichloromethane; acetonitrile; at 20℃; for 2.0h;
To a solution of dibutyl 1H-imidazole-4,5-dicarboxylate (Step 36.1) (20 g, 74.5 mmol) in CH2CI2 (250 mL) and ACN (83 mL) were added successively K2003 (11.33 g, 82 mmol) then dropwise bromine (4.22 mL, 82 mmol). The resulting mixture was stirred 1 hr at RT. The reaction mixture was poured onto aq. Na25203 solution and extracted with CH2CI2. Combined extracts were washed with brine, dried over Mg504, filtered and concentrated under reduced pressure to afford the title product (27.1 g, 74.1 mmol, 99 % yield) as a yellow oil. tR: 1.09 mm (LC-MS 2); ESl-MS: 347/349 [M+H] ESl-MS: 345/347 [M-H] (LC-MS 2); TLC (EtOAc/heptane 1:1) Rf =0.39.The title compound was prepared in analogy to the procedure described in Step 36.2 using methyl 1 H-imidazole-4,5-dicarboxylate at RT for 2 hr. The reaction mixture was quenched with a minimum volume of aq. Na25203 solution and the yellow suspension was filtered and the filtrate was concentrated under reduced pressure. About 30-40 % of the total amount of product was obtained. Most of the product had crystallized and required repeated dissolution with hot THFMeOH 4:1 mixture (500 mL). The extraction from a saturated aq. phase was producing even less product. The individual extracted batches, probably containing some KBr salt, were combined and dried under reduced pressure. The residual salt was always checked after each treatment with THF-MeOH if still some product was present. It required 4 extraction cycles to remove the polar and poorly soluble product from the inorganic salts. TLC (CH2CI2/MeOH 10:1) Rf= 0.42.
8.3 g
With N-Bromosuccinimide; In acetonitrile; at 50℃; for 4.0h;
(1) Dimethyl 1H-imidazole-4,5-dicarboxylate (9.6 g, 52 mmol) was dissolved in acetonitrile (200 mE), and N-bromosuccinimide (13.92 g, 78 mmol) was added thereto, and then the mixture was stirred at 50 C. for 4 hours. After the reaction, water was added and the mixture was extracted twice with ethyl acetate. After being washed with saturated aqueous sodium thiosulfate and saturated aqueous sodium chloride, the organic layer was dried over anhydrous sodium sulfate. The organic layer was concentrated to obtain dimethyl 2-bromo-1H-imidazole-4,5-dicarboxylate (8.3 g). This material was used as is in the next reaction without further purification:10217] ‘H-NMR (CDC13) ?: 10.56 (1H, s), 3.96 (6H, s);10218] ESI-MS mlz=263 (M+H).
With bromine; In water; at 60℃; for 1.0h;
To a solution of dimethyl 1H-imidazole-4,5-dicarboxylate (1.58g) in water (15mL), was added bromine (4.11g). The mixture was stirred at 60C for Ihr.The solvent was evaporated in vacuo and the residue was triturated with ether to give the target compound (2.35g) as a solid.NMR (DMSO-d6) : d 3.81(6H, s).MASS m/z : 286 (M-l).
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