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Synthesis of Dibenzylbutane and 9,8$\prime$-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl2 and Mg in the Presence of Zr ansa-Complexesстатья
- Авторы: Kovyazin Pavel V., Ivchenko Pavel V., Nifant’ev Ilya E., Parfenova Lyudmila V.
- Сборник: ECSOC-25
- Год издания: 2021
- Место издания: MDPI
- DOI: 10.3390/ecsoc-25-11776
- Аннотация: 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 ansa-zirconocenes of various structures were tested as catalysts of allylbenzene cyclometalation with ethylaluminum dichloride (EtAlCl2) and Mg. The effects of the organophosphorus compounds, hexamethylphosphoramide (HMPA) and triphenylphosphine (PPh3), on the chemo- and regioselectivity of the reaction were studied. The use of η5-indenyl or fluorenyl ansa-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.
- Добавил в систему: Нифантьев Илья Эдуардович