A new metabolite of phenacetin was identified as 4-hydroxy-3-methylthioacetanilide (11). The synthesis of 11 and the isomeric 4-hydroxy-2-methylthioacetanilide (4) as well as that of the previously reported phenacetin metabolite 3-[(5-acetamido-2-hydroxyphenyl) thio] alanine (18) is described.
