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Organic & Biomolecular Chemistry
Page 4 of 5
COMMUNICATION
Journal Name
would for cyclic voltammetry measurements. FuDnOdiI:n1g0.f1o0r39th/Dis0rOeBs0e1a15rc1Gh
was provided by Yokohama National University (kyodo kenkyu
suishin program B).
photocatalytic pathways. Thus, single electron transfer from the
superoxide radical (O2 ¯) to radical cation intermediate
occur to afford the cycloadduct 3a
·
B
.
Conflicts of interest
There are no conflicts to declare.
Notes and references
1
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Scheme 2 Proposed reaction mechanism. PMP: p-methoxyphenyl
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(a) K. Tanaka, M. Kishimoto, Y. Asada, Y. Tanaka, Y. Hoshino
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Figure 1 Stern–Volmer plots for ortho-quinone methide 1a (red line) and pentafulvene
2a (blue line).
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In conclusion, we have developed organic photoredox
catalyzed [4+2] cycloaddition of pentafulvenes under visible
light irradiation. The various pentafulvenes reacted with ortho-
quinone methides in the presence of thioxanthylium organic
photoredox catalyst (TXT) under green light irradiation
furnished the corresponding [4+2] cycloadducts in good yields.
Pentafulvenes bearing aromatic and aliphatic groups could be
successfully applied to the reaction. Based on the quantum yield
of the reaction (Φ = 0.15), the reaction mainly proceeds via
photocatalytic pathways. We hope that the reaction system
provides an efficient and sustainable method for cycloaddition
reaction of fulvenes.
Hoshino and K. Honda, Tetrahedron Lett., 2016, 57
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5914−5918; (h) K. Tanaka, Y. Hoshino and K. Honda,
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,
4
10 For some recent examples of organo photoredox catalysis
under visible light irradiation, see: (a) L. Mei, J. M. Veleta and
T. L. Gianetti, J. Am. Chem. Soc., 2020, 142, 12056; (b) I. A.
MacKenzie, L. Wang, N. P. R. Onuska, O. F. Williams, K. Begam,
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580, 76; (c) W. Chen, Z. Huang, N. E. S. Tay, B. Giglio, M. Wang,
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Acknowledgements
1170; (d) J. B. McManus, J. D. Griffin, A. R. White and D. A.
Nicewicz, J. Am. Chem. Soc., 2020, 142, 10325; (e) N. J.
4 | J. Name., 2012, 00, 1-3
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