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COMMUNICATION
Journal Name
(
1
a
O
and S. Angerer, J. Med. Chem., 1990, 33, 153; (b) T. Polossek,
DOI: 10.1039/C9CC02388G
N
N
R. Ambros, S. Angerer, G. Brandi, A. Mannschreck and E.
Angerer, J. Med. Chem., 1992, 35, 3537; (c) R. Faust, P. J.
Garratt, R. Jones and L.-K. Yeh, J. Med. Chem., 2000, 43, 1050;
(d) G. A. Kraus, V. Gupta, M. Kohut and N. Sing, Bioorg. Med.
Chem. Lett., 2009, 19, 5539; (e) R. Ambros, S. Angerer and W.
Wiegrebe, Arch. Pharm. (Weinheim), 1988, 321, 743.
O
O
V
Bz
VI
O
IV
fac-IVIr(ppy)3
Bz
-
Cl-
SET
III
IV
SET
Cl-
-
2
a
2a
fac-*IIIIr(pp y* )3
SET
II
(4)(a) S. J. Mahoney and E. Fillion, Chem. Eur. J., 2012, 18, 68; (b)
K. Morimoto, K. Hirano, T. Satoh and M. Miura, Org. Lett.,
2010, 12, 2068; (c) Y.-J. Li, J.-T. Zhu, H.-B. Xie, S. Li, D.-J. Peng,
Z.-K. Li, Y.-M. Wu and Y.-F Gong, Chem. Commun., 2012, 48,
H+
-
N
N
hv
fac-IIIIr(ppy)3
O
O
I
Bz
Bz
VII
3aa
3
136; (d) M.-H. Shen, Y.-P. Pan, Z.-H. Jia, X.-T. Ren, P. Zhang
and H.-D. Xu, Org. Biomol. Chem., 2015, 13, 4851.
Figure 3. The proposed reaction mechanism.
(
5) (a) C. Bressy, D. Alberico and M. Lautens, J. Am. Chem. Soc.,
2
005, 127, 13148; (b) F. Jafarpour and M. Lautens, Org.
III
with visible light to provide a photoexcited state,* fac- Ir(ppy)
II), which readily reduces benzoyl chloride 2a via single-
electron transfer (SET) to deliver the corresponding radical
anion followed by the expulsion of the chloride ion to generate
the acyl radical (IV), along with the oxidized photocatalyst fac-
Ir(ppy) (III). The acyl radical (IV) then undergoes the addition
3
reaction with 1a to deliver the new α-acyl radical (V). Species V
undergoes the cyclization reaction to produce radical VI, and
the oxidation of species VI occurs via SET with the oxidized
photocatalyst fac- Ir(ppy)
3
Lett., 2013, 15, 6018.
1
8
(
(
(
(
6)W.-T. Wei, X.-J. Dong, S.-Z. Nie, Y.-Y Chen, X.-J. Zhang and M.
Yan, Org. Lett., 2013, 15, 6018.
7)N. Fuentes, W.-Q. Kong, L. Fernández-Sánchez, E. Merino and
C. Nevado, J. Am. Chem. Soc., 2015, 137, 964.
8)For selected reviews, see: (a) C. K. Prier, D. A. Rankic and D.
W. C. MacMillan, Chem. Rev. , 2013, 113, 5322; (b) M. H.
Shaw, J. Twilton and D. W. C. MacMillan, J. Org. Chem., 2016,
81, 6898; (c) J. Xuan and W.-J. Xiao, Angew. Chem. Int. Ed.,
IV
2
012, 51, 6828; (d) M. D. Märkäus, J. A. Porco and C. R. J.
IV
Stephenson, Chem. Rev., 2016, 116, 9683; (e) N. A. Romero
and D. A. Nicewicz, Chem. Rev., 2016, 116, 10075.
3
(III) to form corresponding cation
(I)
VII, regenerating the ground state photocatalyst fac-Ir(ppy)
3
(
9)For selected examples: (a) P. Kohls, D. Jadhav, G. Pandey and
O. Reiser, Org. Lett., 2012, 14, 672; (b) F. Rusch, L.-N.Unkel, D.
Alpers, F. Hoffmann and M. Brasholz, Chem. Eur. J., 2015, 21,
to complete the photocatalysis cycle. Alternatively, the species
VI can be oxidize by benzoyl chloride to provide the cation VII,
along with the generated acyl radical IV. Quantum yield
measurements (Φ = 1.73) suggest a chain mechamism is
possible (see the ESI†). Finally, rapid deprotonation of cation
VII occurs to regain its aromaticity and deliver the desired
product 3aa.
In summary, we have developed an efficient photocatalysis
transformation for the synthesis of the indolo[2,1-
a]isoquinoline core structure. A variety of designed and
synthesized substrates readily reacted with the acyl radical
generated from aroyl chlorides to furnish fused-indole
derivatives in good to excellent yields in the visible-light
promoted radical cascade cyclization process. This redox
neutral reaction features mild reaction conditions and
exceptional functional group tolerance.
8
5
336; (c) J. Cheng, J. Xie and C.-J. Zhu, Chem. Commun., 2018,
4, 1655.
(
10) (a) J. Liu, Q. Liu, H. Yi, C. Qin, R. Bai, X. Qi, Y. Lan, and A. Lei,
Angew. Chem. Int. Ed., 2014, 53, 502; (b) L. Chu, J. M.
Lipshultz, and D. W. C. MacMillan, Angew. Chem. Int. Ed.,
2015, 54, 7929; (c) H. Huang, G. Zhang and Y. Chen, Angew.
Chem. Int. Ed., 2015, 54, 7872; (d) H. Tan, H. Li, W. Ji and L.
Wang, Angew. Chem. Int. Ed., 2015, 54, 8374.
11) (a) G. Bergonzini, C. Cassani and C.-J. Wallentin, Angew.
Chem. Int. Ed., 2015, 54, 14066; (b) M. Zhang, R. Ruzi, J. Xi,
N. Li, Z. Wu, W. Li, S. Yu and C. Zhu, Org. Lett., 2017, 19,
3430; (c) M. Zhang, J. Xie and C. Zhu, Nat. Commun., 2018, 9,
(
3
517; (d) E. E. Stache, A. B. Ertel, T. Rovis and A.l G. Doyle,
ACS Catal., 2018, 8, 11134.
(
12) S. Mukherjee, R. A. Garza-Sanchez , A. Tlahuext-Aca and F.
Glorius, Angew. Chem. Int. Ed., 2017, 56, 14723; (b) X.
Zhang and D. W. C. MacMillan, J. Am. Chem. Soc., 2017, 139,
11353; (c) X.-Z Fan, J.-W. Rong, H.-L. Wu, Q. Zhou, H.-P.
Deng, J.-D. Tan, C.-W. Xue, L.-Z. Wu, H-R. Tao and Jie Wu,
Angew. Chem. Int. Ed., 2018, 57, 8514.
13) (a) C-G. Li, G-Q. Xu, P.-F. Xu, Org. Lett., 2017, 19, 512; (b) S.-
M. Xu, J.-Q. Chen, D. Liu, Y. Bao, Y.-M. Liang, P.-F. Xu, Org.
Chem. Front., 2017, 4, 1331.
We are grateful to the NSFC (21632003, 21871116 and
1572087), the key program of Gansu province (17ZD2GC011)
and the ‘‘111’’ program from the MOE of P. R. China for
financial support.
2
(
(
14) (a) J.-Q. Chen, Y.-L. Wei, G.-Q. Xu, Y.-M. Liang and P.-F. Xu,
Chem. Commun., 2016, 52, 6455; (b) G.-Q. Xu, J.-T. Xu, Z.-T.
Feng, H. Liang, Z.-Y. Wang, Y. Qin and P.-F. Xu, Angew.
Chem. Int. Ed., 2018, 57, 5110; (c) Y.-N, Zhao, Y-C. Luo, Z.-Y.
Wang, and P.-F. Xu, Chem. Commun., 2018, 54, 3993; (d)
W.-L. Yu, J.-Q. Chen, Y.-L. Wei, Z.-Y. Wang and P.-F. Xu,
Chem. Commun., 2018, 54, 1948.
Conflicts of interest
The authors declare no conflict of interest.
Notes and references
(
15) D. Liu, M.-J. Jiao, Z.-T. Feng, X.-Z. Wang, G.-Q. Xu and P.-F.
(
1)For selected reviews, see: (a) A. J. Kochanowska-Karamyan
and M. T. Hamann, Chem. Rev., 2010, 110, 4489; (b) M. Somei
and F. Yamada, Nat. Prod. Rep., 2004, 21, 278; (c) D. A.
Horton, G. T. Bourne and M. L. Smythe, Chem. Rev., 2003,
03, 893.
2)J. Ewing, G. Hughes, E. Ritchie and W. C. Taylor, Nature, 1952,
69, 618.
Xu, Org. Lett., 2018, 20, 5700.
(
(
(
16) D. P. Hari, B. König, Chem. Commun., 2014, 50, 6688.
17) K. Kalyanasundaram, Coord. Chem. Rev., 1982, 46, 159.
18) K. Dedeian, P. I. Djurovich, F. O. Garces, G. Carlson, and R. J.
Watts, Inorg. Chem., 1991, 30, 1685.
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| J. Name., 2012, 00, 1-3
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