Potassium Hydroxide → L-Phenylalanine

The methyl ester from Example 9 (i) (0.58 g, 1.2 mmol) was dissolved in ethanol (10 mL) and a solution of potassium hydroxide (0.223 g, 4 mmol) in water (4 mL) was added. This solution was stirred at room temperature for 1.5 hours. The ethanol was evaporated, the residue was diluted with water (10 mL) and the basic solution was extracted with ether. The aqueous layer was acidified to pH 3.5 with 10% hydrochloric acid solution, and the cooled suspension was then filtered, washed with water and dried in vacuum to provide 0.46 g (82%) of N-[1-(2-chlorophenyl)methyl-2-propylthio-1H-imidazol-5-yl}methylcarbonyl]-L-phenylalanine; mp 120°-121° C.