ИСТИНА

Biphenyl is an important intermediate in organic chemistry and a structural fragment of a wide range of compounds with high pharmacological activity. [1] Currently, one of the most effective methods for obtaining biphenyls are cross-coupling reactions [2]. In turn, all these methods require the use of expensive palladium compounds as a catalyst. Fluorine-containing compounds are of an especial interest in organic and inorganic chemistry, chemistry of materials as well as in the production of drugs and agrochemicals. One of the key problems in the synthetic and medical chemistry is the design of structures with a strictly prescribed position of a fluorine atom. [3] This work is devoted to the development of an alternative selective method for obtaining fluorine-containing biphenyls. This approach is based on the Diels-Alder reaction of β-fluoro-β-nitrostyrenes with 2,3-dimethyl-1,3-butadiene (Scheme 1). The subsequent elimination of HNO2 from the resulting adducts with spontaneous oxidation of diene intermediate by air oxygen leads to the corresponding o-fluorinated biphenyl.The starting β-fluoro-β-nitrostyrenes were prepared according to the previously developed method (Scheme 2), based on the radical nitration of 2-bromo-2-fluorostyrenes. [4] 2-Bromo-2-fluorostyrenes, in turn, were obtained by the reaction of catalytic olefenation from the corresponding aromatic aldehydes. [5] This work was supported by the Russian Science Foundation (RSF) (Grant No. 17-73-10358). This work was partially supported by the Russian Federation President Grant for leading scientific schools № 4687.2018.3. References [1] Z. J. Jain, P. S. Gide, R. S. Kankate, Arabian Journal of Chemistry. 2017, 10, S2051–S2066 [2] D.R. Stuart, K. Fagnou, Science 2007, 316(5828), 1172-1175; [3] Chem. Rev. 2015, Special Issue Fluorine Chemistry, 2, 563-1296 [4] V. A. Motornov, V. M. Muzalevskiy, A. A. Tabolin, R. A. Novikov, Yu. V. Nelyubina, V.G. Nenajdenko, S. L. Ioffe, J. Org. Chem. 2017, 82, 5274–5284. [5] A. V. Shastin, V. M. Muzalevsky, E. S. Balenkova, V. G. Nenajdenko, Mendeleev Commun. 2006, 16, 178−180