10.1002/adsc.201900699
Advanced Synthesis & Catalysis
Scheme 5. Postulated mechanism.
2014, 510, 485-496. i) J. Mahatthananchai, J. W. Bode,
Acc. Chem. Res. 2014, 47, 696-707. j) R. S. Menon, A.
T. Biju, V. Nair, Chem. Soc. Rev. 2015, 44, 5040-5052.
k) D. M. Flanigan, F. Romanov-Michailidis, N. A.
White, T. Rovis, Chem. Rev. 2015, 15, 9307-9387. l) R.
S. Menon, A. T. Biju, V. Nair, Beilstein J. Org. Chem.
2016, 12, 444-461. m) M. H. Wang, K. A. Scheidt,
Angew. Chem. Int. Ed. 2016, 55, 14912-14922.
[2] a) R. Breslow, J. Am. Chem. Soc. 1958, 80, 3719-3726.
b) D. Janssen-Muller, M. Schedler, M. Fleige, C. G.
Daniliuc, F. Glorius, Angew. Chem. Int. Ed. 2015, 54,
12492-12496.
[3] a) E. M. Phillips, J. M. Roberts, K. A. Scheidt, Org.
Lett. 2010, 12, 2830-2833. b) Y. R. Zhang, L. He, X.
Wu, P. L. Shao, S. Ye, Org. Lett. 2008, 10, 277-280. c)
T. Y. Jian, L. He, C. Tang, S. Ye, Angew. Chem. Int. Ed.
2011, 50, 9104-9107. d) J. Mo, R. Yang, X. Chen, B.
Tiwari, Y. R. Chi, Org. Lett. 2013, 15, 50-53. e) F. Li,
Z. Wu, J. Wang, Angew. Chem. Int. Ed. 2015, 54, 656-
659.
[4] a) C. Guo, B. Sahoo, C. G. Daniliuc, F. Glorius, J. Am.
Chem. Soc. 2014, 136, 17402-17405. b) C. Guo, M.
Schedler, C. G. Daniliuc, F. Glorius, Angew. Chem., Int.
Ed. 2014, 53, 10232-10236. c) N. A. White, D. A.
DiRocco, T. Rovis, J. Am. Chem. Soc. 2013, 135, 8504-
8507. d) X. Y. Chen, J. W. Xiong, Q. Liu, S. Li, H.
Sheng, C. von Essen, K. Rissanen, D. Enders, Angew.
Chem., Int. Ed. 2018, 57, 300-304.
[5] a) C. Zhang, J. F. Hooper, D. W. Lupton, ACS Catal.
2017, 7, 2583-2596. b) S. Mondal, S. R. Yetra, S.
Mukherjee, A. T. Biju, Acc. Chem. Res. 2019, 52, 425-
436. c) B. Liu, W. Wang, R. Huang, J. Yan, J. Wu, W.
Xue, S. Yang, Z. Jin, Y. R. Chi, Org. Lett. 2018, 20,
260-263. d) S. Mondal, A. Ghosh, S. Mukherjee, A. T.
Biju, Org. Lett. 2018, 20, 4499-4503. e) H. Lu, C. Y.
Tan, H. X. Zhang, J. L. Zhang, J. Y. Liu, H. Y. Li, P. F.
Xu, J. Org. Chem. 2018, 83, 15245-15255. f) Q. Liu, X.
Y. Chen, R. Puttreddy, K. Rissanen, D. Enders, Angew.
Chem., Int. Ed. 2018, 57, 17100-17103. g) J. Wang, Y.
Li, J. Sun, H. Wang, Z. Jin, Y. R. Chi, ACS Catal. 2018,
8, 9859-9864. h) S. Mukherjee, A. Ghosh, U. K. Marelli,
A. T. Biju, Org. Lett. 2018, 20, 2952-2955. i) K. Q.
Chen, Z. H. Gao, S. Ye, Angew. Chem., Int. Ed. 2019,
58, 1183-1187.
[6] For selected examples of NHC-catalyzed [3 + 2]
Annulation, see: a) X.-Y. Chen, Z.-H. Gao, C.-Y. Song,
C.-L. Zhang, Z.-X. Wang, S. Ye, Angew. Chem., Int. Ed.
2014, 53, 11611-11615. b) D. Jiang, S. Dong, W. Tang,
T. Lu, D. Du, J. Org. Chem. 2015, 80, 11593-11597. c)
Q. Zhao, B. Han, B. Wang, H.-J. Leng, C. Peng, W.
Huang, RSC Adv. 2015, 5, 26972-26976. d) K.-Q. Chen,
Y. Li, C.-L. Zhang, D.-Q. Sun, S. Ye, Org. Biomol.
Chem. 2016, 14, 2007-2014. e) X. Wu, B. Liu, Y.
Zhang, M. Jeret, H. Wang, P. Zheng, S. Yang, B.-A.
Song, Y. R. Chi, Angew. Chem., Int. Ed. 2016, 55,
12280-12284. f) X.-Y. Chen, K.-Q. Chen, D.-Q. Sun, S.
Ye, Chem. Sci. 2017, 8, 1936-1941.
In summary, an unprecedented NHC-catalyzed
β-indolylation of α-bromoenals with indoles has been
described. A number of biaryl methylene fragment-
based products was generated by using simple and
readily available starting materials. Good to high
yields and broad scope are generally observed.
Further investigations on asymmetric version are
currently underway in our laboratory.
Experimental Section
A mixture of 1 (0.4 mmol), 2 (0.6 mmol), 3 (0.44 mmol),
NHC cat. (0.04 mmol), LiOAc (0.6 mmol), and 4Å MS (50
mg) in anhydrous CHCl3 (2.0 mL) was stirred at room
temperature for 48 h. After completion, solvent was
removed under reduced pressure and purified by column
chromatography to give the product as white solid or
colorless oil.
Acknowledgements
Generous financial support for this work is provided by: the
National Natural Science Foundation of China (21672121,
21871160), Hubei Provincial Department of Education
(T201419), and Education Department of Hubei Province Science
and Technology Research Project (Nos. Q20162803).
References
[1] For selected recent reviews on NHC catalysis, see: a) D.
Enders, O. Niemeier, A. Henseler, Chem. Rev. 2007,
107, 5606-5655. b) A. T. Biju, N. Kuhl, F. Glorius, Acc.
Chem. Res. 2011, 44, 1182-1195. c) D. T. Cohen, K. A.
Scheidt, Chem. Sci. 2012, 3, 53-57. d) X. Bugaut, F.
Glorius, Chem. Soc. Rev. 2012, 41, 3511-3522. e) A.
Grossmann, D. Enders, Angew. Chem. Int. Ed. 2012, 51,
314-325. f) S. J. Ryan, L. Candish, D. W. Lupton,
Chem. Soc. Rev. 2013, 42, 4906-4917. g) S. J. Connon,
Angew. Chem. Int. Ed. 2014, 53, 1203-1205. h) M. N.
Hopkinson, C. Richter, M. Schedler, F. Glorius, Nature
[7] For selected examples of NHC-catalyzed [3 + 3]
Annulation, see: a) S. J. Ryan, L. Candish, D. W.
Lupton, J. Am. Chem. Soc. 2009, 131, 14176-14177. b)
S. D. Sarkar, A. Studer, Angew. Chem., Int. Ed. 2010,
49, 9266-9269. c) F.-G. Sun, L.-H. Sun, S. Ye, Adv.
4
This article is protected by copyright. All rights reserved.