3-[(3-Amino-4-methylamino-benzoyl)-pyridin-2-yl-amino]-propionic acid ethyl ester

429659-01-8

212322-56-0

(D) Preparation of Intermediate VI: In a hydrogenation reactor, 43 g of ethyl 3-(4-(methylamino)-3-nitro-N-(pyridin-2-yl)benzoylamino)propionate and 4.7 g of nickel Nguyenne catalyst were added. 4 mL of tetrahydrofuran was added as solvent and three nitrogen substitutions were performed to remove air. The reaction mixture was then stirred under hydrogen atmosphere and heated to 60°C. The reaction process was monitored by thin layer chromatography (TLC). After completion of the reaction, a filtration operation was carried out and the filter cake was washed with a small amount of tetrahydrofuran. The filter cake was recovered and disposed properly. The filtrate was dried over anhydrous sodium sulfate, diafiltrated again and finally concentrated to dryness under reduced pressure to give 38.3 g of intermediate VI (6) in 96% yield.