Ethanol → 2-(2-(O-tolylamino)benzo[d]oxazol-6-yl)acetic acid

Participants

Reaction Steps

A mixture of (4-amino-3-hydroxy-phenyl)-acetic acid ethyl ester (3.3 g, Reference Example 3) and o-tolylisothiocyanate (2.5 mL) in ethanol (150 mL) was stirred at room temperature for about 2 hours. After standing at room temperature overnight the mixture was evaporated and the residue was subjected to flash chromatography on silica eluting with a mixture of pentane and ethyl acetate (7:3, v/v) to give a yellow foam. A solution of this material in ethanol (150 mL) was treated with dicyclohexylcarbodiimide (3.0 g) and the mixture was heated at reflux temperature for 2 hours. The mixture was evaporated and the residue subjected to short column chromatography (on silica eluting with a mixture of tert-butyl methyl ether and dichloromethane, 1:19 to 1:9 v/v). The resulting light yellow oil was dissolved in ethanol (100 mL) and the solution was treated with sodium hydroxide solution (15 mL, 1M) then heated at reflux temperature for 2 hours. The reaction mixture was evaporated and the residue was dissolved in water. The solution was washed with ethyl acetate and the aqueous layer was acidified to pH 1 by addition of concentrated hydrochloric acid. The resulting white precipitate was collected by filtration, then washed thoroughly with water, and then dried to give the title compound (1.8 g) as a white solid.

Provenance & Evidence