Synthesis and recyclization of 4-chloromethylflavylium and 4-chloromethylbenzothiapyrilium salts

Condensation of -chloro-o-hydroxyacetophenones in the presence of perchloric acid yields 4-chloromethylflavylium perchlorates. 4-Chloromethylbenzothiapyrilium perchlorates were obtained by intramolecular cyclization of 2-arylmercapto-5-chloropentanones-4. In the reaction of 4-chloromethylflavylium salts with aqueous alkali, chloromethyleneflavenes (the anhydro bases of the starting salts) and 3-phenacylbenzob]furanes were separated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 766–769, June, 1987.