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a 4-Bromo-2,5-difluorobenzaldehyde n-Butyllithium (1.95M in hexanes, 10.2 ml)) was added dropwise to a stirred solution of 1,4-dibromo-2,5-difluorobenzene (5 g, 18.4 mmol) in diethyl ether (60 ml) at -70° C. After 1 h, the solution was warmed to 0° C. over 1 h, diluted with water, the layers separated and the ether layer dried over sodium sulphate and evaporated. Purification by column chromatography (Biotage), eluding with 5percent ethyl acetate/hexane, gave a yellow oil (1.82 g). 1H NMR 300 MHz (CDCl3) 10.28 (1H, s), 7.61 (1H, dd), 7.48 (1H, dd).
With ammonium chloride; In tetrahydrofuran; N,N-dimethyl-formamide;
Method 6 4-Bromo-2,5-difluorobenzaldehyde To 1,4-dibromo-2,5-difluorobenzene (10.28 g, 37.81 mmol) in tetrahydrofuran (80 mL) at -40° C. was isopropylmagnesium chloride lithium chloride complex (29.1 mL, 37.81 mmol) added dropwise. After 1 h at -40° C. was N,N-dimethylformamide (58 mL, 756 mmol) added and the mixture was stirred for 30 minutes at -40° C. NH4Cl (2M, aq, 100 mL) was added and the mixture was extracted with ethyl acetate. The organic phase was dried with MgSO4 and concentrated to give 4-bromo-2,5-difluorobenzaldehyde (6.20 g, 74percent) as a solid. 1H NMR (500 MHz, CHLOROFORM-d) delta ppm 10.28 (d, 1H) 7.61 (dd, 1H) 7.48 (dd, 1 H).
Example 31 Preparation of 4-bromo-2,5-difluorobenzaldehyde [0289] 2,5-dibromo-1,4-difluorobenzene (10.0 g, 36.77 mmol) in diethyl ether (150 mL) at -78 C. was added n-butyl lithium (2.5 M in Hexanes, 14.86 mL, 37.15 mmol) dropwise under nitrogen. The reaction mixture was stirred at -78 C. for 30 min. Dry DMF (3.13 mL, 40.46 mmol) in diethyl ether (10 mL) was added dropwise and reaction was slowly warmed to room temperature over 2 h. The reaction was quenched with aqueous saturated ammonium chloride solution (25 mL) and extracted with diethyl ether. The organic phase was washed with saturated brine solution, dried (Na2SO4), filtered, and concentrated under reduced pressure (Note: Product is highly volatile). The crude product was purified by flash chromatography (SiO2, eluting with 2-20% ethyl acetate in hexanes) to provide the title compound as a pale yellow solid (7.0 g, 86%): 1H NMR (400 MHz, CDCl3): delta 7.50 (dd, J=5.08, 8.92 Hz, 1H), 7.62 (dd, J=5.80, 7.68 Hz, 1H), 10.30 (d, J=2.76 Hz, 1H).
66.7%
To a stirred solution of XXXII-1 (12 g, 44.1 mmol) in THF (150 mL) was added dropwise of XXXII-1A (44.1 mmol, 34 mL, 1.3 M) at -40 C. After stirred 1 h at -40 C., DMF (64 g, 882 mmol) was added and the mixture was stirred overnight. NH4Cl (aq., 2M) was added and the mixture was extracted with EtOAc. The organic phase was dried with Na2SO4. The solvent was removed in vacuo and the residue was purified by column chromatography (PE/EA=10/1) to afford XXXII-2 (6.5 g, yield: 66.7%).
55.8%
To a solution of l,4-dibromo-2,5-difluorobenzene (15 g, 55 mmol) in toluene (600 mL) cooled to -78 C was added butyllithium (22 mL, 55 mmol) and the reaction was kept at -78 C for 30 minutes. N,N-dimethylformamide (4.4 g, 61 mmol) was added and the reaction was stirred for 2 hours while warming to ambient temperature. To the reaction was added water (200 mL) and EtOAc (400 mL) and the organic layers were separated. The organic layer was washed with brine (200 mL), dried over MgS04, filtered and concentrated in vacuo. The crude material was chromatographed eluting with 5% EtOAc/Hexane to yield 4-bromo-2,5-difluorobenzaldehyde (6.7 g, 55.8%).
37%
n-Butyl lithium (3.6 ml,7.7 mmol) was added drop wise to a solution of 1,4- dibromo-2,5-difluoro-benzene (2g, 7.35mmol) in dry ether at -78C under nitrogen atmosphere and the resulting mixture was stirred at -78C for 30 minutes. This was followed by the addition of DMF (0.85ml, 11.03mmol) in dry THF. The resultant was stirred at room temperature for 1 hour. The reaction was monitored by TLC (5% ethyl acetate in hexane). The reaction mixture was partitioned between ethyl acetate and saturated ammonium chloride. The organic layer was concentrated and purified by column chromatography on silica gel (2% ethyl acetate in hexane) to afford 600mg of the product (37% yield).1H NM (CDC13, 300 MHZ): delta 10.27-10.26 (d, 1H), 7.61-7.57 (t, 1H), 7.49- 7.44 (q, 1H)
To a Et2O solution (200 mL) containing 1,4-dibromo-2,5-difluorobenzene (19.72 g, 72.5 mmol) cooled to -78 degrees C. was added 30.5 mL of a 2.5 M hexanes solution of n-BuLi (76.2 mmol). The resulting green solution was stirred for 20 min at -78 degrees C. when DMF (7.95 g, 10.8 mmol) was added. The reaction was stirred for 30 min and then quenched with H2O. The organics were taken up in EtOAc and washed with sat. NaHSO4 followed by drying over MgSO4. The solvent was removed in vacuo and the residual oil purified on the Biotage (2-5% EtOAc/hexanes) yielding 11.4 g (51.7 mmol) of 4-bromo-2,5-difluorobenzaldehyde. 1H NMR (400 MHz, CDCl3) delta 10.2 (s, 1H), 7.57 (m, 1H), 7.45 (m, 1H) ppm.
tert-butyl (R)-(1-(4-bromo-2,5-difluorophenyl)pyrrolidin-3-yl)(methyl)carbamate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
46%
With tris-(dibenzylideneacetone)dipalladium(0); caesium carbonate; 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl; In toluene; at 80℃; for 4h;Inert atmosphere;
(1019) (1020) intermediate 31-1 (1021) [00354] Into a 100-mL round-bottom flask that purged and maintained under an inert atmosphere of nitrogen was added 4-bromo-2-chloro-l-iodobenzene (1.20 g, 3.78 mmol), benzyl piperazine-l -carboxylate (0.924 g, 4, 19 mmol), NaOtBu (1.10 g, 1 1.4 mmol), XantPhos (0.695 g, 1.20 mmol), Pd2(dba)3 (0.393 g, 0.430 mmol), and toluene (10 mL). The reaction mixture was stirred for 4 h at 60 C and then concentrated in vacuo to provide a crude product that was purified by FCC eluting with ethyl acetate/petroleum ether (1 : 10) to afford benzyl 4-(4-bromo-2- chlorophenyl)piperazine-l -carboxylate as a colorless oil (713 mg, 46%). LCMS (ESI, m/z) 409, 41 1 [ M 1 [ j .
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