xyphenyl)-5-propenylbenzofuran.According to the invention, the benzofuran compounds have the following formula where R may be hydrogen or a linear or branched alkyl chain with 2 to 6 carbon atoms, or an alkyl chain substituted by amino, nitro groups; R is preferably hydrogen or C1-C3 alkyl.Said benzofuran compounds are known and can be prepared by conventional methods, for example by reaction of a