2-Methylphenyl isothiocyanate → 2-(4-Methoxy-2-o-tolylaminobenzoxazol-6-yl)acetic acid

A mixture of methyl 4-amino-3-hydroxy-5-methoxy-phenylacetate [0.295 g, Reference Example 10(a)] and o-tolylisothiocyanate (2.14 g) in ethanol (25 mL) was left at room temperature for 3 days. The mixture was evaporated and a solution of the residue in ethanol (20 mL) was treated with dicyclohexylcarbodiimide (0.308 g). The mixture was heated at reflux temperature for 2.5 hours and then evaporated. The resulting brown oil was dissolved in methanol (30 mL) and the solution was treated with sodium hydroxide solution (10 mL, 1M) and then heated at 45° C. for one hour. The mixtures was diluted with water and then partially evaporated. The residue was washed twice with diethyl ether and the pH of the aqueous phase was adjusted to 1-2 by addition of dilute hydrochloric acid. The mixture was then extracted with ethyl acetate and the organic phase was washed with water, then with brine, then dried and then evaporated to give the title compound (0.42 g) as a golden solid.