Pyridine → N-(Cyclohexanecarbonyl)-L-tyrosine

Participants

Reaction Conditions

Reaction Steps

Cyclohexanoyl chloride (7 mL, 47 mmole) was added dropwise to a stirred solution of dry pyridine (400 mL) and O-benzyltyrosine benzyl ester (25 g, 46.8 mmole). The reaction temperature was maintained at 0° C. throughout the addition. The reaction mixture was stirred for an additional 2 hours after the addition was complete. The reaction mixture was concentrated to dryness in vacuo to provide a solid material. The solid was washed with aqueous hydrochloric acid (1N, 4×400 mL). The residue was dissolved in ethyl acetate (300 mL), washed with aqueous hydrochloric acid (1N, 2×500 mL), aqueous sodium bicarbonate (2×300 mL), and dried over magnesium sulfate. Filtration, followed by concentration in vacuo, provided an oil which was dissolved in methanol/tetrahydrofuran (400 mL/70 mL) and was hydrogenated at atmospheric pressure and room temperature over 10% palladium on carbon (600 mg). The reaction mixture was filtered through Celite and concentrated in vacuo to provide a solid which was recrystallized from ethyl acetate/hexane. The crystals were collected to-provide the N-cyclohexanoyl-(L)-tyrosine (8.7 g, 64%) as a white solid.

Provenance & Evidence