N-Tosyl-D-phenylalanine → N-((4-Methylphenyl)sulfonyl)-L-phenylalanine

Participants

Reaction Steps

In a mixture of 50 ml of ethyl acetate and 50 ml of diethylether were dissolved under heating 7.4 g of 2,4-cis-4-ethoxycarbonyl-2-(4-fluoro-2-methylphenyl)piperidine and 4.0 g of N-p-toluenesulfonyl-D-phenylalanine. The solvent was concentrated by heating, 30 ml of diisopropyl ether was added thereto and the mixture was stirred. Precipitated crystals were removed and mother liquor was washed with a concentrated aqueous ammonia solution, dried and concentrated under reduced pressure. To the residue was added 4.0 g of N-p-toluenesulfonyl-L-phenylalanine, and 50 ml of ethyl acetate and 30 ml of diisopropyl ether were added thereto and dissolved by heating, the mixture was stirred at room temperature for 16 hours. Precipitated crystals were collected by filtration, washed with diisopropyl ether, and dried, to give 4.0 g of N-p-toluenesulfonyl-L-phenylalanine salt of (2R,4S)-4-ethoxycarbonyl-2-(4-fluoro-2-methylphenyl)-4-piperidine.

Provenance & Evidence