Conversion of alpha-benzoyl-homoveratronitrile (I) into benzopyrylium perchlorate derivative (II) is performed by reaction with perchloric acid in acetic anhydride. The desired compound is then obtained by treatment of (II) with hydrazine hydrate in refluxing acetonitrile. Alternatively, the target product can be obtained as follows: Treatment of homoveratronitrile derivative (I) with hydrazine hydrate in refluxing acetic acid yields pyrazole (III), which is then acylated with acetyl chloride (IV) by means of Et3N in refluxing benzene to furnish acetylamino derivative (V). Finally, cyclization is induced by treatment of (V) with perchloric acid in refluxing acetic anhydride/nitromethane.