| Summary: | The aim of the research is the development of a one-pot method for the synthesis of lignans, natural compounds that show a wide spectrum of biological activities. For this purpose, the <i>ansa</i>-zirconocenes of various structures were tested as catalysts of allylbenzene cyclometalation with ethylaluminum dichloride (EtAlCl<sub>2</sub>) and Mg. The effects of the organophosphorus compounds, hexamethylphosphoramide (HMPA) and triphenylphosphine (PPh<sub>3</sub>), on the chemo- and regioselectivity of the reaction were studied. The use of <i>η</i><sup>5</sup>-indenyl or fluorenyl <i>ansa</i>-complexes with ethanediyl or dimethylsilylene bridges, as well as a biscyclopentadienyl complex with Si-bound ligands as catalysts in the presence of HMPA, yields the formation of cyclometalation products in a total yield of 70%. Cyclometalation product composition is represented by two regioisomers, 3,4-dibenzyl- and 2,4-dibenzyl-substituted alumolanes, with a ratio of (1-2):1, in which hydrolysis provides corresponding dibenzylbutane lignan and 9,8′-neo-lignan.
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