Oxalyl chloride → 4-[[(2,4-Dimethylpyridin-3-yl)Carbonyl]Amino]-N-[[1-[4-(methylsulfonyl)Butyl]Cyclopentyl]Carbonyl]-L-Phenylalanine

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Reaction Steps

To a solution of 2,4-dimethylpyridinecarboxylic acid (0.6 mmol, 102 mg) in dichloromethane (3 mL) was added a drop of DMF and oxalyl chloride (0.78 mmol, 99 mg) at 0° C. (ice bath). The solution was stirred at this temperature for 30 min, warmed to room temperature and stirred for an additional 1 h. Then, the solvent and excess oxalyl chloride was removed under vacuum and the residue was dried under high vacuum. To this 4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]carbonyl]-L-phenylalanine methyl ester (0.5 mmol, 212 mg) was added and the mixture was dissolved in dichloromethane (5 mL). To this clear solution was added DIPEA (2.0 mmol, 0.258 g) at room temperature. The mixture was stirred for 15 h at which time TLC analysis of the mixture indicated the absence of starting material. Then, the mixture was diluted with dichloromethane (20 mL) and water (100 mL). The two layers were separated and the organic layer was washed with saturated sodium bicarbonate solution (20 mL), brine solution (30 mL) and dried over anhydrous magnesium sulfate. Filtration of the drying agent and removal of the solvent gave a crude product which was purified by silica gel column chromatography to afford 0.232 g (80%) of a white solid. HR MS (C29H39N3O6S): Obs. mass, 558.2629. Calcd. mass, 558.2638, M+H).

Provenance & Evidence