Synthesis of tetraalkoxyaryldihydrobenzo[g]indazoles from metabolites of dill and parsley seeds essential oil

An efficient method for the conversion of available plant allylpolyalkoxybenzenes into unsubstituted and arylsubstituted polymethoxylated aryldihydrobenzo[g]indazoles, analogues of combretastatin A4, has been developed. The selective demethylation of target compounds resulted in indazoles with different position of OH-group. Their structure was confirmed by X-ray analysis. A sea urchin embryo assay revealed the lack of tubulin-related antimitotic activity of aryldihydrobenzo[g]indazoles with systemic toxicity of a compound featuring OH group and 1-unsubstituted pyrazole ring. [Display omitted] •Synthesis of polyalkoxyaryldihydrobenzoindazoles, cis-analogues of combretastatin.•Efficient cyclization method for synthesis of polyalkoxytetralones.•Plant allylpolyalkoxybenzenes apiol and dillapiol were used as starting material.•X-ray diffraction study of selected compounds.•Evaluation of biological activity on the sea urchin embryo model.