The condensation of 5,7-dimethylbenzofuran (I) with dimethyl glutaconate (II) by means of Pd(OAc)2 in hot acetic acid gives the adduct (III), which is hydrogenated with H2 over Pd in ethyl acetate to yield the corresponding glutarate (IV). The hydrolysis of (IV) with KOH in methanol affords the expected glutaric acid (V), which is treated with hot acetic anhydride to provide the glutaric anhydride (VI). The reaction of (VI) with ammonia furnishes the corresponding glutarimide (VII), which is finally hydroxylated by means of OsO4 and pyridine in ethyl ether.