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A flask containing 6-bromo-2,3-pyridinediamine (2.14 g, 11.4 mmol) in 30 mL of formic acid was heated to reflux for 4.5 hr. Upon cooling the solution was made basic with 5.0 M NaOH. The organics were extracted with EtOAc (4×) and dried over MgSO4. The solvent was removed in vacuo yielding 1.84 g (9.29 mmol) of 5-bromo-1H-imidazo[4,5-b]pyridine which was taken on crude. 1H NMR (400 MHz, d6-DMSO) delta 8.44 (s, 1H), 7.94 (d, 1H, J=8.2 Hz), 7.37 (d, 1H, J=8.5 Hz) ppm.
To a THF solution (80 mL) containing <strong>[28279-52-9]5-bromo-1H-imidazo[4,5-b]pyridine</strong> (1.81 g, 9.14 mmol) cooled to 0 degrees C. was added NaH (439 mg, 10.9 mmol, 60% dispersion in mineral oil). The solution was stirred for 30 min and then trityl chloride (3.31 g, 11.9 mmol) and nBu4NI (34 mg, 0.09 mmol, 1 mole %) were added. The solution was heated to reflux for 4 hr and upon cooling was diluted with H2O. The organics were extracted with EtOAc (3×), dried over MgSO4 and the solvent removed in vacuo. The residual oil was purified on the Biotage (30-70%EtOAc/hexanes) yielding 3.57 g (8.10 mmol) of 5-bromo-1-(triphenylmethyl)-1H-imidazo[4,5-b]pyridine as a mixture of regioisomers.
benzyl (2R,3S)-2-(3-bromo-2-oxopropyl)-3-((tert-butyldimethylsilyl)oxy)piperidine-1-carboxylate[ No CAS ]
benzyl (2R,3S)-2-(3-(5-bromo-1H-imidazo[4,5-b]pyridin-1-yl)-2-oxopropyl)-3-((tert-butyldimethylsilyl)oxy)piperidine-1-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
40%
With potassium carbonate; In N,N-dimethyl-formamide; at 20.0℃; for 3h;
5-Bromo-lH-imidazo[4,5-b]pyridine (245 mg, 1.24 mmol) was dissolved in N,N- dimethylformamide (5 mL, 0.25 M) to which potassium carbonate (324 mg, 2.48 mmol) was added and then stirred at room temperature for 10 minutes. Then, benzyl (2R,3S)-2-(3-bromo-2- oxopropyl)-3-((tert-bu1yldimethylsilyl)oxy)piperidine-l-carboxylate (600 mg, 1.24 mmol) was added thereto and stirred at room temperature for 3 hours. When the reaction was completed, the solvent was removed and the resulting mixture was diluted with ethyl acetate and washed with saturated sodium chloride solution. The organic layer was collected, dried over magnesium sulfate, filtered and concentrated under reduced pressure, and then purified by column chromatography (dichloromethane:methanol = 10:1) to give the title compound (300 mg, yield: 40%).
benzyl (2R,3S)-2-(3-bromo-2-oxopropyl)-3-((tert-butyldimethylsilyl)oxy)piperidine-1-carboxylate[ No CAS ]
benzyl (2R,3S)-2-(3-(5-bromo-3H-imidazo[4,5-b]pyridin-3-yl)-2-oxopropyl)-3-((tert-butyldimethylsilyl)oxy)piperidine-1-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
40%
With potassium carbonate; In N,N-dimethyl-formamide; at 20.0℃; for 3h;
Step 43-1: Preparation of benzyl (2RT3S)-2-(3-(5-bromo-3H-imidazo[4,5- b]pvridm-3-yI)-2-oxopropyl)-3-((tert-butyldm 5-Bromo-lH-imidazo[4,5-b]pyridine (245 mg, 1.24 mmol) was dissolved in N,N- dimethylformamide (5 mL, 0.25 M) to which potassium carbonate (324 mg, 2.48 mmol) was added and then stirred at room temperature for 10 minutes. Then, benzyl (2R,3S)-2-(3-bromo-2- oxopropyl)-3-((tert-butyldimemylsilyl)oxy)piperidine-l-carboxylate (600 mg, 1.24 mmol) was added thereto and stirred at room temperature for 3 hours. When the reaction was completed, the solvent was removed and the resulting mixture was diluted with ethyl acetate and washed with saturated sodium chloride solution. The organic layer was collected, dried over magnesium sulfate, filtered and concentrated under reduced pressure, and then purified by column chromatography (dichloromethane:methanol = 10:1) to give the title compound (300 mg, yield: 40%).
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