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Organic & Biomolecular Chemistry
Page 4 of 5
DOI: 10.1039/C8OB01837E
ARTICLE
Journal Name
2
3
For 5,10ꢀdihydroindolo[3,2ꢀ
of ortho
H. E. Ho, K. Oniwa, Y. Yamamoto and T. Jin, Org. Lett.
2016, 18, 2487–2490; ( ) J. Yu, D. ZhangꢀNegrerie and Y.
Du, Org. Lett., 2016, 18, 3322–3325.
For other heteroacenes with 6ꢀ5ꢀ5ꢀ6 ring systems via cascade
cyclizations of ortho orthoꢀdifunctionalised
diphenylacetylenes, see: ( ) S. Yamaguchi, C. Xu and K.
Tamao, J. Am. Chem. Soc., 2003, 125, 13662–13663; ( ) K.
Takimiya, Y. Kunugi, Y. Konda, H. Ebata, Y. Toyoshima and
T. Otsubo, J. Am. Chem. Soc., 2006, 128, 3044–3050; ( ) A.
Fukazawa, M. Hara, T. Okamoto, E.ꢀC. Son, C. Xu, K.
Tamao and S. Yamaguchi, Org. Lett., 2008, 10, 913–916; (
A. Fukazawa, H. Yamada and S. Yamaguchi, Angew. Chem.,
Int. Ed., 2008, 47, 5582–5585; ( ) J. F. Araneda, B. Neue, W.
E. Piers and M. Parvez, Angew. Chem., Int. Ed., 2012, 51,
8546–8550; ( ) Q.ꢀW. Zhang, K. An and W. He, Angew.
Chem., Int. Ed., 2014, 53, 5667–5671; ( ) Y. Xu, Z. Wang, Z.
b
]indoles via cascade cyclisations
General procedure for the gold(I)/rhodium(II)-catalysed
cascade cyclisation of 2-[(2-azidophenyl)ethynyl]anilines 1.
A Schlenk tube containing a magnetic stirring bar was charged
,
orthoꢀdifunctionalised diphenylacetylenes, see: (a)
,
b
with 2ꢀ[(2ꢀAzidophenyl)ethynyl]aniline
(SPhos)AuNTf2 (1.8 mg, 2.0 mol, 2.0 mol%) and Rh2(esp)2
(2.3 mg, 3.0 mol, 3.0 mol%) under nitrogen atmosphere.
1
(0.100 mmol),
µ
,
µ
a
Toluene (1.0 mL) was added via a syringe through the septum,
and the mixture was stirred at 80 °C or 100 °C for 12–18 h.
After completion, the reaction mixture was filtered through a
plug of Florisil® eluting with hexane–AcOEt (1:1~3:1). The
filtrate was concentrated, and the residue was purified by
preparative thinꢀlayer chromatography (hexane–AcOEt) to give
b
c
d)
e
5,10ꢀdihydroindolo[3,2ꢀ
General procedure for the base-promoted rhodium(II)-
catalysed cascade cyclisation of 2-[(2-
azidophenyl)ethynyl]phenols 4. A Schlenk tube containing a
magnetic stirring bar was charged with 2ꢀ[(2ꢀ
azidophenyl)ethynyl]phenol (0.100 mmol), Rh2(esp)2 (3.8
mg, 50 mol, 5.0 mol%) and K2CO3 (27.6 mg, 0.200 mmol, 2.0
b]indole 2.
f
g
Gan, Q. Xi, Z. Duan and F. Mathey, Org. Lett., 2015, 17,
1732–1734.
For other synthetic studies on 5,10ꢀdihydroindolo[3,2ꢀ
4
4
b
]indoles, see: (
X. Wan, R. Yang and Y. Liu, Chem. Commun., 2012, 48,
12225–12227; ( ) N. Jana, Q. Nguyen and T. G. Driver, J.
Org. Chem., 2014, 79, 2781–2791; ( ) T. Q. Hung, S.
a) L. Qiu, C. Yu, N. Zhao, W. Chen, Y. Guo,
µ
equiv) under nitrogen atmosphere. Toluene (1.0 mL) was added
via a syringe through the septum, and the mixture was stirred at
80 °C for 12–18 h. After completion, the reaction mixture was
filtered through a plug of Florisil® eluting with hexane–AcOEt
(2:1~3:1). The filtrate was concentrated, and the residue was
purified by preparative thinꢀlayer chromatography (hexane–
b
c
Hancker, A. Villinger, S. Lochbrunner, T. T. Dang, A.
Friedrich, W. Breitsprecher and P. Langer, Org. Biomol.
Chem., 2015, 13, 583–591; (
Kanai and Y. Kuninobu, Chem. Eur. J., 2015, 21, 8365–8368;
) M. A. Truong and K. Nakano, J. Org. Chem., 2015, 80,
11566–11572. ( ) P. V. Santhini, A. Krishnan R, S. A. Babu,
d) K. Saito, P. K. Chikkade, M.
(
e
f
AcOEt or toluene–hexane) to give 10Hꢀbenzofuro[3,2ꢀb]indole
B. S. Simethy, G. Das, V. K. Praveen, S. Varughese and J.
John, J. Org. Chem., 2017, 82, 10537–10548.
5.
5
For other synthetic studies on heteroacenes with 6ꢀ5ꢀ5ꢀ6 ring
systems, see: (
Phys. Chem. C, 2011, 115, 11265–11274; (
a
) M. Shimizu, K. Mochida and T. Hiyama, J.
) T. Mori, T.
Conflicts of interest
b
Nishimura, T. Yamamoto, I. Doi, E. Miyazaki, I. Osaka and
K. Takimiya, J. Am. Chem. Soc., 2013, 135, 13900–13913;
There are no conflicts to declare.
(
c
) L. Qiu, X. Wang, N. Zhao, S. Xu, Z. An, X. Zhuang, Z.
Lan, L. Wen and X. Wan, J. Org. Chem., 2014, 79, 11339–
11348; ( ) M. Takahashi, K. Nakano and K. Nozaki, J. Org.
Chem. 2015, 80, 3790–3797; N. Kamimoto, D.
Schollmeyer, K. Mitsudo, S. Suga and S. R. Waldvogel,
Chem. Eur. J., 2015, 21, 8257–8261; ( ) K. Saito, P. K.
Chikkade, M. Kanai and Y. Kuninobu, Chem. Eur. J., 2015,
21, 8365–8368; ( ) X.ꢀY. Wang, A. Narita, X. Feng and K.
Müllen, J. Am. Chem. Soc., 2015, 137, 7668–7671; ( ) H.
Huang, P. Dang, L. Wu, Y. Liang and J. Liu, Tetrahedron
Lett., 2016, 57, 574–577; ( ) D. Luo, G. Wu, H. Yang, M.
Liu, W. Gao, X. Huang, J. Chen and H. Wu, J. Org. Chem.
2016, 81, 4485–4493; ( ) M. Matsumura, A. Muranaka, R.
Kurihara, M. Kanai, K. Yoshida, N. Kakusawa, D.
Hashizume, M. Uchiyama and S. Yasuike, Tetrahedron
2016, 72, 8085–8090; ( ) P. V. Santhini, S. A. Babu, A.
Krishnan R, E. Suresh and J. John, Org. Lett., 2017, 19,
2458–2461; ( ) K. Mitsudo, S. Tanaka, R. Isobuchi, T. Inada,
H. Mandai, T. Korenaga, A. Wakamiya, Y. Murata and S.
Suga, Org. Lett., 2017, 19, 2564–2567; ( ) D. Chen, D.
Yuan, C. Zhang, H. Wu, J. Zhang, B. Li and X. Zhu, J. Org.
Chem., 2017, 82, 10920–10927; ( ) M. Shimizu, D. Ryuse
and T. Kinoshita, Chem. Eur. J., 2017, 23, 14623–14630.
For a review on 1,4ꢀdihydropyrrolo[3,2ꢀ ]pyrrole derivatives,
Acknowledgements
d
,
(e)
This work was supported by JSPS, Japan (GrantꢀinꢀAid for
Scientific Research (C) No. 16K05783). We thank S. Oyama
for collecting NMR data of 5c
f
.
g
h
Notes and references
i
1
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f
) C.
l
,
g
m
h
n
i
j
6
7
b
k
see: A. Janiga and D. T. Gryko, Chem. Asian J., 2014, 9,
3036–3045.
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(l
m
b
]indole derivatives in organic electronics, see: (
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b
4 | J. Name., 2012, 00, 1-3
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