Sodium Hydroxide → 3-(5-{3-Methoxy-4-[3-(2-methylphenyl)ureido]-phenylacetylamino}pyrid-2-yl)-propanoic acid

A stirred mixture of 3-(5-{3-methoxy-4-[3-(2-methylphenyl)ureido]-phenylacetylamino}pyrid-2-yl)-propanoic acid ethyl ester [0.62 g, Reference Example 3(a)] and ethanol (40 ml) was treated with 4% aqueous sodium hydroxide solution (3.2 ml) and then heated to 50° C. After stirring at 50° C. for 7 hours, the reaction mixture was cooled and then left to stand at room temperature over night. The reaction mixture was partially concentrated in vacuo, washed with diethyl ether and then acidified to pH 1.0 by addition of hydrochloric acid (1M). The resultant white solid was collected, washed with water and then dried in vacuo. Recrystallisation from aqueous acetonitrile gave the title compound (0.32 g) as a white crystalline solid, m.p. 191-192° C. (with decomposition). MS: MH+ 463.