4-(3´-Methoxyphenoxy)-phenylacetic Acidの合成

Abstract

4-(3′-Methoxyphenoxy)-phenylacetic acid (III) was prepared by the following two methods. The first method was the hydrolysis of ethyl 4-(3′-methoxyphenoxy)-phenylacetate (II), obtained by the Ullmann condensation of ethyl p-bromophenylacetate (I) and resorcinol monomethyl ether, the yield being 3.3-6.7% of the theoretical amount. The second method was the Willgerodt reaction of 3′-methoxy-4-acetyldiphenyl ether (V) obtained by the Ullmann condensation of p-bromoacetophenone (IV) and resorcinol mono-methyl ether. In this Willgerodt reaction, methods of reacting ammonia water and sulfur in pyridine base solvent, in a sealed tube or in the autoclave, or using ammonium polysulfide, were attempted but in all these cases, corresponding acid amide could not be obtained and only thioamide (VI) was obtained. Hydrolysis of the thioamide thus obtained yielded the objective acid (III), m.p. 81-82°, as crystallized from carbon tetrachloride. This acid was completely identical with the acid obtained by the Ullmann condensation but the yield was very poor in every case, being 3-10% of the theory when using a sealed tube, 3.9% in an autoclave, and 5.6% when using polysulfide.