A strategy for the preparation of cyclic polyarenes based on single electron transfer-promoted photocyclization reactions
Single electron transfer (SET)-promoted photocyclization reactions of substrates comprised of benzylsilane tethered to phthalimides were subjected to an exploratory study in order to probe a new approach for the preparation of cyclic polyarenes. The results show that UV irradiation of the substrates leads to efficient photochemical reactions that are initiated by SET from benzylsilane moieties to the excited phthalimide acceptor. Ensuing desilylation reactions of the benzylsilane cation radical moieties in the intermediate zwitterionic biradicals and proton transfer gives biradical precursors of the cyclic polyarene products. The observations made in this effort suggests that SET photochemical methods, which have been employed earlier to generate cyclic poly-ethers, -thioethers and -amides, serve as a useful method to access potentially interesting macrocyclic targets.
KeywordsSET photochemistry Cyclic polyarenes Benzylsilanes Phthalimides
This investigation was supported financially by the National Research Foundation of Korea Grant to U.C.Y. supported by the Korean Government (KRF-2008-521-C00156). In addition, we offer our congratulation to Professor Kazuhiko Mizuno on the excellent career he has had in the academic profession and for the important scientific contributions he has made to the fields of organic chemistry and organic photochemistry.
- 2.D. Rehm, A. Weller, Kinetics of fluorescence quenching by electron transfer and H-atom transfer. Isr. J. Chem. 8, 259–269 (1970)Google Scholar
- 10.A.J.Y. Lan, R.O. Heuckeroth, P.S. Mariano, Electron transfer induced photocyclization reactions of arene-iminium salt systems. Effects of cation radical deprotonation and desilylation on the nature and efficiencies of reaction pathways followed. J. Am. Chem. Soc. 109, 2738–2745 (1987)CrossRefGoogle Scholar
- 16.D.W. Cho, U.C. Yoon, P.S. Mariano, Studies leading to the development of a single electron transfer photochemical strategy for the synthesis of macrocyclic polyethers, polythioethers and polyamides. Acc. Chem. Res. 44, 204–215 (2011)Google Scholar
- 18.D.W. Cho, J.H. Choi, S.W. Oh, C. Quan, U.C. Yoon, R. Wang, S. Yang, P.S. Mariano, Single electron transfer promoted photocyclization reactions of linked acceptor-polydonor systems: effects of chain length and type on the efficiencies of macrocyclic ring forming photoreactions of tethered α-silyl ether phthalimide substrates. J. Am. Chem. Soc. 130, 2276–2284 (2008)CrossRefGoogle Scholar
- 19.D.W. Cho, C. Quan, H.J. Park, J.H. Choi, S.R. Kim, T.G. Hyung, U.C. Yoon, S.H. Kim, Y.X. Jin, P.S. Mariano, Studies aimed at elucidating factors involved in the control of chemoselectivity in single electron transfer promoted photoreactions of branched-polydonor substituted phthalimides. Tetrahedron 66, 3173–3186 (2010)CrossRefGoogle Scholar
- 24.M. Machida, M. Nakamura, K. Oda, H. Takechi, K. Ohno, H. Nakai, Y. Sato, Y. Kanaoka, Photochemistry of the phthalimide system. 40. Photoreaction of phthalimides possessing an ortho-methylphenyl group in their N-side chain. Synthesis of tetracyclic nitrogen heterocycles. Heterocycles 26, 2683–2690 (1987)CrossRefGoogle Scholar
- 25.J.O. Howell, J.M. Concalves, C. Amatore, L. Klasinc, R.M. Wightman, J.K. Kochi, Electron transfer from aromatic hydrocarbons and their π-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials. J. Am. Chem. Soc. 106, 3968–3976 (1984)CrossRefGoogle Scholar