反应详情

温度

0 °C

A solution of 2-(3-chloro-4-methylsulfonyl-phenyl)-3-(4-oxo-cyclohexyl)-propionic acid (prepared as in Example 58, 267 mg, 0.75 mmol) in methylene chloride (10 mL) was treated with N,N-dimethylformamide (3 drops) and then cooled to 0° C. The reaction mixture was then treated with a 2.0M solution of oxalyl chloride in methylene chloride (0.45 mL, 0.90 mmol). The reaction mixture was stirred at 25° C. for 30 min and then concentrated in vacuo to remove solvents and excess oxalyl chloride. The resulting residue was re-dissolved in dry tetrahydrofuran (10 mL) and was treated dropwise with a solution of 2-amino-5-bromopyrazine (261 mg, 1.50 mmol, prepared according to Tetrahedron 1988, 44, 2977–2983) in tetrahydrofuran (10 mL) and pyridine (0.30 mL, 3.75 mmol). The resulting reaction mixture was stirred at 25° C. for 2 h. The reaction mixture was then diluted with a 1N aqueous citric acid solution (25 mL) and then concentrated to remove tetrahydrofuran. The remaining aqueous residue was then extracted with a 3/2 solution of chloroform/methanol (2×25 mL). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated in vacuo. Biotage chromatography (FLASH 40M, Silica, 35/65 hexanes/ethyl acetate) afforded N-(5-bromo-pyrazin-2-yl)-2-(3-chloro-4-methanesulfonyl-phenyl)-3-(4-oxo-cyclohexyl)-propionamide (193 mg, 50%) as a yellow foam: EI-HRMS m/e calcd for C20H21BrClN3O4S (M+H)+ 514.0198, found 514.0200.

1. concentrationconcentrated in vacuo
2. customto remove solvents and excess oxalyl chloride
3. dissolutionThe resulting residue was re-dissolved in dry tetrahydrofuran (10 mL)
4. customThe resulting reaction mixture
5. stirringwas stirred at 25° C. for 2 h
6. concentrationconcentrated
7. customto remove tetrahydrofuran
8. extractionThe remaining aqueous residue was then extracted with a 3/2 solution of chloroform/methanol (2×25 mL)
9. dry with materialThe combined organic extracts were dried over sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated in vacuo