Amine-effected cyclization of chalcone dihalides to aurones

Article abstract of DOI:10.1016/S0040-4020(01)87903-5

The possibility of employing the amine-catalysed cyclization of αβ-dibromodihydrochalcones and α-bromochalcones as a general synthesis of aurones was studied using cyclohexylamine and the most representative member of each class of these αβ-disubstituted ketones and α-halogeno chalcones. Overall yields of heterocyclic products were generally poor except from 4′6′-dimethoxy- and 3-nitro-substituted chalcone systems; aurones were obtained in fair yield from the former and in excellent yield from the latter. 22′-Diacetoxychalcone dibromide and 22′-diacetoxy-α-bromochalcone cyclised to a 2-benzoylbenzofuran to the exclusion of the corresponding aurone and flavone.