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DOI: 10.1039/C7CC09140K
COMMUNICATION
Journal Name
*
2
For the use of aryl halides as a reactant, see: (a) D. P. Curran,
D. Kim, H. T. Liu, W. Shen, J. Am. Chem. Soc. 1988, 110
5900−5902. (b) S. Yanagisawa, K. Ueda, T. Taniguchi, K. Itami,
Org. Lett., 2008, 10, 4673−4676. (c) E. Shirakawa, K. Itoh, T.
Higashino, T. Hayashi, J. Am. Chem. Soc. 2010, 132,
15537−15539. (d) C. L. Sun, H. Li, D. G. Yu, M. Yu, X. Zhou, X.
Phen
DCB
ν
h
Phen;
DCB;
,
Phen
NC
CN
Phen
Ar
DCB
+ OH-
4
+
X
+ H+
X
5
Y. Lu, K. Huang, S. F. Zheng, B. J. Li, Z. J. Shi, Nat. Chem. 2010,
, 1044−1049.
ArB(OH)3 ArB(OH)3
Ar
3
Ar
12
2
+ H+
DCB
CH CN
+
2
Ar H
10
CH2CN
CH3CN
3
4
For the use of aryl carboxylic acids as a reactant, see: (a) J.
Kan, S. Huang, J. Lin, M. Zhang, W. Su, Angew. Chem., Int. Ed.
2015, 54, 2199−2203. (b) S. Seo, M.; Slater, M. F. Greaney,
Org. Lett. 2012, 14, 2650−2653. (c) G. J. P. Perry, J. M.
+ CH3CN
13
Scheme 5. A plausible mechanism in the photoreaction of
and
3
4
.
Quibell, A. Panigrahi, I. Larrosa, J. Am. Chem. Soc. 2017, 139
,
this photoinduced radical addition of 3a to 4a is about 0.2. In
contrast to the analogous photoreaction of alkyl carboxylic
acids that take place via decarboxylation to produce alkyl
radicals, reactions of the arylborates require the use of 5
rather 1 equiv. of an alkene. The difference is a likely
consequence of the higher reactivity of aryl radicals, which can
abstract a hydrogen atom from CH3CN to produce a reduced
product 10. The back transfer from the radical anion of DCB to
the resulting cyanomethyl radical 13 generates cyanomethyl
anion followed by the protonation to reproduce CH3CN as
reported by us.17 Thus, the competitive radical reduction and
addition processes are existed in the photoreaction, and the
high rate of the radical addition to alkene requires the high
concentration (100 mM) of alkene. Unfortunately, the use of a
high alkene concentration (> 100 mM) makes oligomerization
more efficient, and requires the high concentrations of
photocatalyst for preventing oligomerization.18
11527
−11536.
For the use of aryl boronic acids as a reactant, see: (a) A. S.
Demir, H. Findik, Tetrahedron 2008, 64, 6196−6201. (b) Y.
Fujiwara, V. Domingo, I. B. Seiple, R. Gianatassio, M. Del Bel,
P. S. Baran, J. Am. Chem. Soc. 2011, 133, 3292−3295. (c) A.
Dickschat A. Studer, Org. Lett. 2010, 12, 3972–3974. (d) G.
Yan, M. Yang, X. Wu, Org. Biomol. Chem., 2013, 11, 7999–
8008.
For the use of aryl triflates as a reactant, see: W. Liu, X. Yang,
Y. Gao, C.-J. Li, J. Am. Chem. Soc. 2017, 139, 8621−8627.
For the use of aryl diazonium salts as a reactant, see: (a) C.
Galli, Chem. Rev. 1988, 88, 765−792. (b) D. P. Hari, P. Schroll,
B. König, J. Am. Chem. Soc. 2012, 134, 2958−2961.
For review of the use of aryl diazonium salts with
photoredox catalyst such as Ir, Ru, and eosin Y, see: (a) I.
Ghosh, L. Marzo, A. Das, R. Shaikh, B. König, Acc. Chem. Res.
2016, 49, 1566−1577. (b) M. Majek, A. J. Wangelin, Acc.
Chem. Res. 2016, 49, 2316−2327.
(a) H. Meerwein, E. Buchner, K. van Emsterk, J. Prakt. Chem.
1939, 152, 237−266. (b) C. S. Rondestvedt, Org. React. 1976,
225−259. (c) C. Molinaro, J. Mowat, F. Gosselin, P. D. O’Shea,
J.-F. Marcoux, R. Angelaud, I. W. Davies, J. Org. Chem. 2007,
72, 1856−1858.
5
6
7
8
9
In conclusion, the results of this effort show that aryl-boronic
acids and -borates undergo photoredox catalyzed addition
reactions with electron deficient alkenes via a pathway
involving the intermediacy of aryl radicals. The process
represents a new type of Meerwein arylation, in which stable
arylboronic acids serve as substrates. Also, the process takes
place using alkyl- and alkenyl-boronic acids. A variety of aryl-
boronic acids and borates, and alkenes are acceptable
substrates for this photoreaction. The process represents a
new synthetic method for introducing aryl groups. Further
investigations of the applicability of this methodology in
synthetic organic chemistry are underway.
For the use of aryl diazonium salts without Cu(I) in Meerwein
arylation, see: (a) D. P. Hari, B. König, Angew. Chem., Int. Ed.
2013, 52, 4734−4743. (b) M. Hartmann, Y. Li, A. Studer, J.
Am. Chem. Soc. 2012, 134, 16516−16519.
10 For review, see; Y. Yoshimi, J. Photochem. Photobiol. A 2017,
342, 116–130.
11 (a) Y. Yoshimi,T. Itou, M. Hatanaka, Chem. Commun. 2007,
5244–5246. (b) T. Itou, Y. Yoshimi, T. Morita, Y. Tokunaga, M.
Hatanaka, Tetrahedron 2009, 65, 263–269. (c) Y. Yoshimi, M.
Masuda, T. Mizunashi, K. Nishikawa, K. Maeda, N. Koshida, T.
Itou, T. Morita, M. Hatanaka, Org. Lett. 2009, 11, 4652–4655.
(d) K. Nishikawa, Y. Yoshimi, K. Maeda, T. Morita, I.
Takahashi, T. Itou, S. Inagaki, M. Hatanaka, J. Org. Chem.
2013, 78, 582–589.
This work was supported by the Japan Society for the
Promotion of Science (JSPS), Grant-in-Aid no. 17K05779, for
scientific research.
12 N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457−2483.
13 H. M. Tuononen, M. Parvez, R. Roesler, Chem. Commun.
2007, 4522−4524.
14 Y. Yoshimi, S. Hayashi, K. Nishikawa, Y. Haga, K. Maeda, T.
Morita, T. Itou, Y. Okada, M. Hatanaka, Molecules 2010, 15
Conflicts of interest
There are no conflicts to declare.
,
2623–2630.
15 Triphenylborane reacts with t-butoxy radical to form t-
BuOBPh3 radical followed by the homolysis of B-Ph bond to
provide phenyl radical, see: D. Grilier, K. U. Ingold, L. K.
Patterson, J. C. Scaiano, R. D. Small Jr, J. Am. Chem. Soc.
1979, 101, 3780−3785.
Notes and references
1
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,
16 Photoreaction of alkyltriphenylborate with dicyanoarene
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Chem. Soc. 1985, 107, 6710−6711.
17 Y. Kumagai, T. Naoe, K. Nishikawa, K. Osaka, T. Morita, Y.
Yoshimi, Aust. J. Chem. 2015, 68, 1668–1671.
18 M. Yamawaki, A. Ukai, Y. Kamiya, S. Sugihara, M. Sakai, Y.
4
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4 | J. Name., 2012, 00, 1-3
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