Ir-catalyzed arylation, alkylation of quinones with boronic acids through C-C coupling

Article abstract of DOI:10.1016/j.jorganchem.2014.12.036

Ir-catalyzed arylation, alkylation of quinones with boronic acids was developed under room temperature. Both aryl and alkyl boronic acids are suitable for this transformation. This expands the application scope of the iridium catalyst. This is also an excellent proof that iridium catalysts can be used in the C-C coupling of quinones and naphthoquinones with alkyl boronic acids.

Full text of DOI:10.1016/j.jorganchem.2014.12.036

Journal of Organometallic Chemistry 780 (2015) 30e33
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Ir-catalyzed arylation, alkylation of quinones with boronic acids
through CeC coupling
,
Dawei Wang a *, Bingyang Ge a, Anqi Ju b, Yucheng Zhou a, Chongying Xu a,
,
*
Yuqiang Ding a
a The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University,
Wuxi 214122, China
b Key Laboratory of Eco-textiles, Ministry of Education, College of Textile & Clothing, Jiangnan University, Wuxi 214122, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Ir-catalyzed arylation, alkylation of quinones with boronic acids was developed under room temperature.
Both aryl and alkyl boronic acids are suitable for this transformation. This expands the application scope
of the iridium catalyst. This is also an excellent proof that iridium catalysts can be used in the CeC
coupling of quinones and naphthoquinones with alkyl boronic acids.
Received 20 September 2014
Received in revised form
23 December 2014
Accepted 30 December 2014
Available online 9 January 2015
© 2015 Elsevier B.V. All rights reserved.
Keywords:
Iridium
Alkylation
Quinones
Boronic acids
Coupling
Introduction
CeC bond forming reaction with moderate yields by use of an
iridium catalyst [9a]. Later, Hayashi et al. reported the iridium-
The CeX (X ¼ C, O, N, S) coupling has, in recent decades, become
a commonplace tool for the development of synthetic trans-
formations [1], given that such methodology can provide efficient
and easy routes to the pharmaceuticals and natural compounds
from relatively simple starting materials [2]. One point should be
noted that transition metals play a crucial role in this process.
Palladium, rhodium, copper and ruthenium, which are the most
commonly used, are beneficial for the efficient catalytic conversion
of coupling reactions. Compared to palladium [3], rhodium [4],
copper [5] and ruthenium [6], iridium-catalyzed coupling reactions
are more difficult and less well studied [7]. Actually, iridium com-
pound is much more stable than ruthenium and rhodium com-
pounds under the severe thermal condition or basic condition [8],
this unique character gives an alternative way to explore iridium-
catalyzed CeX couplings under harsh conditions [8]. In 2003,
Mori and co-workers developed a new class of Mizoroki-Heck-type
catalyzed 1,6-addition of arylboronic acids to electron-deficient
dienes with high yields [9b]. In 2014, Lam et al. realized iridium-
catalyzed arylative cyclization of alkynones with arylboronic acids
by 1,4-iridium migration as a key step [10a]. Very recently, Lewis
reported Ir-promoted and Pd-catalyzed direct arylation of arenes
using aryl iodides as coupling reagents [10b]. At the same time,
iridium-catalyzed N-alkylation and C-alkylation using borrowed
hydrogen strategy also achieved some results [11]. For example,
Fujita and Yamaguchi showed iridium-catalyzed synthesis of in-
doles and 1,2,3,4-tetrahydroquinolines using borrow hydrogen
strategy [12]. Kempe, Matute, Peris, Crabtree, Ishii, Madsen et al.
also have reported their results in this area [13].
Quinone derivatives, which are widely distributed in natural
products, have demonstrated important biological and pharma-
ceutical activities [14]. Some quinone and naphthoquinone de-
rivatives are practical intermediates for many drugs, including
antibiotic, antiviral, antitumor, antimalarial and antidiabetic drugs
[15], and they can be synthesized by transition metal catalyzed
couplings of quinones with boron reagents [16], indoles [17], ani-
lines [18] and others [19]. However, the development in CeH
functionalization of quinones and naphthoquinones to synthesize
* Corresponding authors. Tel./fax: þ86 510 85917763.
E-mail addresses: wangdw@jiangnan.edu.cn (D. Wang), yding@jiangnan.edu.cn
(Y. Ding).
http://dx.doi.org/10.1016/j.jorganchem.2014.12.036
0022-328X/© 2015 Elsevier B.V. All rights reserved.

D. Wang et al. / Journal of Organometallic Chemistry 780 (2015) 30e33
31
was separated with a 33% yield. Encouraged by this result, the ac-
tivity of various solvents was evaluated (Table 1, entries 1e5). The
results showed that DCM:H2O ¼ 1:1 was superior to the others. It
was found that the reaction could be finished with an 81% yield
(Table 1, entry 10). Blank testing showed that the reaction could not
occur without iridium catalyst (Table 1, entry 12).
Having established the optimal conditions ([Cp*IrCl2]2 as the
catalyst, and CH2Cl2:H2O ¼ 1:1 as the solvent), we explored the
scope of the arylation of quinones with arylboronic acids. The re-
sults are summarized in Table 2. Generally, all the quinones were
converted completely to produce the corresponding aryl-
substituted quinones. Substrates having various electron-
donating groups, such as Me-, MeO-, tBu-, iPr- and Et-moieties,
can be tolerated in order to obtain the corresponding products
with good yields. However, for the arylboronic with electron
withdrawing group, the desired product was separated at a low
yield (11,12). Moderate to good isolated yields were obtained
regardless of the steric hindrance of substituent groups (7,8,9 and
16,17,18).
Scheme 1. Synthesis of alkyl substituted quinones.
aryl- and alkyl-substituted quinones was comparatively slow.
Consequently, there are limited methods for the synthesis of
substituted quinones, and these methods are mainly focused on
synthesis of aryl-substituted quinones. Among them, the use of
arylboronic acids as starting materials is a typical example.
Recently, Molina and co-workers showed the coupling reaction of
quinones with arylboronic acids to obtain arylquinones [16a]. Baran
and co-workers contributed significantly to the development of
silver-catalyzed CeC bond-forming reactions by using quinones
with arylboronic and alkyl boronic acids [16b]. Zhang and Yu
demonstrated the iron-mediated direct arylation with arylboronic
acids through a radical transfer pathway [16c]. Very recently, we
reported palladium catalyzed CeS coupling and rhodium catalyzed
CeC coupling of quinones in moderate yields [20]. As a result of our
continuing efforts to search for an alternative method to synthesis
of arylquinone derivatives [20], herein we report a simple, conve-
nient method to achieve the Ir-catalyzed arylation, alkylation of
quinones with both aryl- and alkyl-boronic acids with moderate to
good yields (Scheme 1).
Next, a substrate scope study for the alkyl boronic acids was
carried out. As shown in Table 3, various alkyl boronic acids were
smoothly transformed into the corresponding products. Never-
theless, this methodology produced a low to moderate yield.
ꢀ
Recently, Bermejo-Bescos and co-workers reported that several
arylquinones and their derivatives are effective inhibitors of
b-
secretase [21]. For example, compound 24 was detested with
9.33 uM of Ic50 of BACE1 inhibitory activity (Scheme 2). Herein, a
direct reaction of 10.0 g of naphthoquinone with arylboronic acid
Results and discussion
Table 2
Substrate expansion of quinonesa.
We selected the typical phenylboronic acid as a coupling re-
agent, given the attention to recent achievements in organic syn-
thesis. Based on our continuing efforts and results in the
development of new methodology, we selected [Cp*IrCl2]2 as a
catalyst with which to catalyze the reaction between benzoquinone
and phenylboronic acid (Table 1). Interestingly, the desired product
Entry
Quinone
R
Yield [%]b
Table 1
1
2
3
4
5
6
7
8
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Benzoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
Naphthoquinone
H
p-iPr
p-OMe
p-Ph
p-tBu
p-OEt
o-Me
3,5-Dimethyl
p-Me
m-OMe
p-Br
81 (1)
83 (2)
86 (3)
77 (4)
90 (5)
66 (6)
74 (7)
76 (8)
Screening of reaction conditionsa.
9
75 (9)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
80 (10)
31 (11)
52 (12)
70 (13)
75 (14)
71 (15)
76 (16)
73 (17)
84 (18)
81 (19)
85 (20)
69 (21)
65 (22)
79 (23)
83 (24)
72 (25)
Entry
Catalyst
Solvent
Yield [%]b
1
2
3
4
5
6
7
8
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
[Cp*IrCl2]2
e
DCE
CH2Cl2
THF
Toluene
33
39
11
16
<5
67
74
58
53
81
78c
<5
18
26
p-I
2-Naphthylc
o-Me
p-Me
Dioxane
m-Me
3,5-Dimethyl
p-OMe
p-iPr
p-tBu
p-OEt
p-Et
H
p-Ph
m-OMe
CH2Cl2:H2O ¼ 3:1
CH2Cl2:H2O ¼ 2:1
CH2Cl2:H2O ¼ 1:2
CH2Cl2:H2O ¼ 1:3
CH2Cl2:H2O ¼ 1:1
CH2Cl2:H2O ¼ 1:1
CH2Cl2:H2O ¼ 1:1
CH2Cl2:H2O ¼ 1:1
CH2Cl2:H2O ¼ 1:1
9
10
11
12
13
14
IrCl3
[Ir(COD)Cl]2
a
a
Conditions: benzoquinone (0.5 mmol, 1.0 equiv.), phenylboronic acid
(1.5 equiv.), [Ir] (5%), 3 mL solvent, 12 h, rt.
Conditions: Quinone (0.5 mmol, 1.0 equiv.), arylboronic acid (1.5 equiv.),
[Cp*IrCl2]2 (5%), 12 h, rt.
b
b
Isolated yields based on benzoquinone.
40 ꢀC was used.
Isolated yields based on quinone.
2-Naphthylboronic acid was used.
c
c

32
D. Wang et al. / Journal of Organometallic Chemistry 780 (2015) 30e33
Table 3
ether ¼ 1:10) to provide the corresponding product. 2-Phenyl-[1,4]
benzoquinone (1). 1H NMR (400 MHz, CDCl3)
7.52e7.43 (m, 5H),
Alkylation of quinones with boronic acidsa.
d
6.84e6.91 (m, 3H).
Acknowledgments
We gratefully acknowledge financial support of this work by the
National Natural Science Foundation of China (21401080,
21371080), the Natural Science Foundation of Jiangsu Province of
China (BK20130125, BK20140159), China Postdoctoral Science
Foundation (2014M550262) and MOE & SAFEA for the 111 Project
(B13025).
Entry
Quinone
R
Yield [%]b
1
2
3
4
5
Benzoquinone
Benzoquinone
Benzoquinone
Naphthoquinone
Naphthoquinone
Cyclohexyl
Me
nPr
cyclohexyl
nPr
31 (26)
23 (27)
41 (28)
34 (29)
35 (30)
a
Appendix B. Supplementary data
Conditions: quinone (0.5 mmol, 1.0 equiv.), alkyl boronic acid (1.5 equiv.),
[Cp*IrCl2]2 (5%), 12 h, rt.
b
Isolated yields based on quinone.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2014.12.036.
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