Pyridine → N-(5-bromo-pyrazin-2-yl)-2-(3-chloro-4-methanesulfonyl-phenyl)-3-(3-oxo-cyclopentyl)-propionamide

Participants

Reaction Conditions

Reaction Steps

A solution of 2-(3-chloro-4-methanesulfonyl-phenyl)-3-(3-oxo-cyclopentyl)-propionic acid (prepared as in Example 45, 1.05 g, 3.04 mmol) and N,N-dimethylformamide (5 drops) in methylene chloride (10 mL) cooled to 0° C. was treated with oxalyl chloride (0.39 mL, 4.57 mmol). The reaction mixture was stirred at 0° C. for 1 h and then at 25° C. for 1 h. The solution was then concentrated in vacuo, and the orange-brown gel was dissolved in methylene chloride (5 mL). The resulting solution was added dropwise via an addition funnel at 0° C. to a solution of 2-amino-5-bromopyrazine (0.79 g, 4.57 mmol, prepared according to Tetrahedron 1988, 44, 2977–2983) in methylene chloride (5 mL) and pyridine (0.37 mL, 4.57 mmol). The reaction mixture was stirred at 0° C. for 30 min and then at 25° C. for 3 h. The reaction mixture was quenched with a 1N aqueous citric acid solution (10 mL) and stirred for 15 min. The reaction was then diluted with a 1N aqueous citric acid solution (50 mL) and ethyl acetate (75 mL). The organic layer was washed with a saturated aqueous sodium bicarbonate solution (50 mL), water (50 mL), and a saturated aqueous sodium chloride solution (50 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo. Biotage chromatography (FLASH 40M, Silica, 50% ethyl acetate/hexanes) afforded N-(5-bromo-pyrazin-2-yl)-2-(3-chloro-4-methanesulfonyl-phenyl)-3-(3-oxo-cyclopentyl)-propionamide (0.622 g, 41%) as a yellow-orange foam: mp 97–103° C. (foam to gel); (ES)+-HRMS m/e calcd for C19H19BrClN3O4S (M+H)+ 500.0041 found 500.0048.

Provenance & Evidence