Under cooling with ice, aluminum chloride (4.08 parts) was added in small portions to a mixed solution of ethyl 9-chloroformylnonanoate (3.52 parts) and 3,4,5-trimethoxytoluene (formula VII wherein R=H3CO, X=H, Y=H3CO) (2.21 parts) in nitrobenzene (20 volume parts). The mixture was stirred at 0° C. for 16 hours and, then, at room temperature for 1.5 hours. The reaction mixture was rendered acidic with dilute hydrochloric acid and extracted with diethyl ether. By a procedure similar to that described in Example 1 (2), the extract was hydrolyzed and subjected to column chromatography on silicic acid. The fraction eluted by benzenediethyl ether (9:1) yielded 9-(2',3',4'-trimethoxy-6'-methylbenzoyl)nonanoic acid (formula II-1 wherein R=H3CO, X=H, Y=OCH3, n=8, in the free form) (1.82 part). From the fraction eluted by benzene-diethyl ether (5.7:1), there was obtained 9-(2'-hydroxy-3',4'-dimethoxy-6' -methylbenzoyl)nonanoic acid (formula II-1, R=H3CO, X=H, Y=OH, n=8 in the free form) (0.67 part) as colorless needles melting at 75°-76.5° C.
