Ruthenium-Catalyzed Regioselective Direct Ortho-Acyloxylation of Azoarenes with Carboxylic Acids via C–H Bond Activation

Article abstract of DOI:10.1002/ejoc.201801545

A Ru^II-catalyzed highly regioselective C–H acyloxylation of azoarenes with inexpensive alkyl and aryl carboxylic acids as an acyloxylation agent is described. The reaction demonstrates a broad substrate scope and good functional group tolerance

Full text of DOI:10.1002/ejoc.201801545

DOI: 10.1002/ejoc.201801545
Full Paper
C–H Activation
Ruthenium-Catalyzed Regioselective Direct Ortho-Acyloxylation
of Azoarenes with Carboxylic Acids via C–H Bond Activation
Ebrahim Kianmehr*[a] and Sepideh Bahrami Nasab[a]
Abstract: A RuII-catalyzed highly regioselective C–H acyloxyl- onstrates a broad substrate scope and good functional group
ation of azoarenes with inexpensive alkyl and aryl carboxylic tolerance. This method provides a facile procedure to synthe-
acids as an acyloxylation agent is described. The reaction dem- size ortho-acyloxylated azoarene derivatives.
Introduction
ported ortho-phosphonation of aromatic azoarenes using di-
alkyl phosphites.[14] RhIII-catalyzed direct alkylation of azobenz-
enes with allyl acetate was reported by Wang in 2015.[15] Ru-
catalyzed arylation of azobenzene derivatives was reported by
Ackermann's group.[16] Despite the tremendous progress in the
field of transition metal catalyzed C–H functionalization reac-
tions in recent years few C-O bond-forming reactions have been
reported in literatures.[17] The palladium-catalyzed ortho-alk-
oxylation and hydroxylation of aromatic azo compounds were
described by Sun,[18] Chakraborti[19] and Joseph.[20]
In recent years a metal-catalyzed direct acyloxylation reac-
tion has attracted some interest.[21] Most recently Li[22] and co-
workers described the RhIII-catalyzed acyloxylation of various
sp2 C–H bonds with readily available carboxylic acids. In 2014
RhIII-catalyzed direct C–H acetoxylation of enamides with
Cu(OAc)2·H2O as the oxidant and acetate source was reported
by Zhang.[23] Pd-catalyzed chelation-assisted acyloxylation of
C–H bonds has also been investigated.[24] Pd-catalyzed acetox-
ylation of arenes by PhI(OAc)2 as the acetoxylation source was
reported by Sanford and Tato seperately.[25] Palladium-catalyzed
acetoxylation of azoarenes with aryl acylperoxides was de-
scribed by Zeng et al. in 2014[26] (Scheme 1, Equation 1) CuI-
catalyzed acetoxylation of aryl amids was demonstrated by
Zhang and co-workers in 2017.[27] CuII-catalyzed ortho-acyloxyl-
ation of the 2-arylpyridines with anhydride using O2 as the oxid-
ant was reported by Cheng′s group in 2010.[28] RuII-catlayzed
Aromatic azo compounds are highly significant scaffolds in
many functional materials such as dyes,[1] photochemical
switches,[2] protein probes,[3] nonlinear optics[4] and pharma-
ceuticals.[5] 2-acyloxy azoarenes are useful for preparation of
artificial antigens[6] (Figure 1, compound A), and are also used
as precursors for preparation ortho-hydroxy azoarene deriva-
tives which can be utilized in pharmaceuticals.[7] Two chromo-
genic dyes S1Bz and S1Boc can be converted into the chromo-
phore 1-phenylazo-2-naphthol which may be potentially useful
in lithographic procedures and for optical data storage and
sensing applications[8] (Figure1).
Figure 1. Examples of applications of azoarenes.
Synthesis of azobenzene derivatives has been investigated in
recent years.[9] Direct C–H functionalization of azobenzenes has
engrossed significant attention using the azo group as a direct-
ing group.[10] Palladium-catalyzed ortho-acylation of azobenz-
enes with α-oxocarboxylic acids,[11] aldehydes,[12] and toluene
derivatives[13] have been reported recently. Wang′s group re-
[a] School of Chemistry, College of Science, University of Tehran,
Tehran, Iran
E-mail: kianmehr@khayam.ut.ac.ir
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejoc.201801545.
Scheme 1. Direct 2-acyloxylation of azoarenes.
Eur. J. Org. Chem. 0000, 0–0
1
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
acetoxylation 2-pyridyloxyarenes and sulfoximine benzamides results showed that 5 mol-% of Ru-catalyst was the best choice
were reported by Ackermann's group in 2015 and 2017, respec- for completing the reaction (Table 1, entries 7 and 12). A variety
tively.[29] RuII-catlayzed acyloxylation of N-Aryl-2-pyrimidines of solvents were examined. As a result, DME, toluene, PhCl and
and indolines were also reported in 2018.[30] To address these DCE afforded moderate yields of the product (Table 1, entries
reports and in continuation of our interest in this area, we wish 13–16). No reaction occurred when MeOH or DMF applied as
to report a convenient and efficient chelation-assisted ruth- the solvent (Table 1, entries 17 and 18). A set of agent additives
enium-catalyzed ortho-benzoxylation of the sp2 C–H bond of was probed and revealed that KPF6 turned out to be the most
azoarenes with carboxylic acids in the presence of K2S2O8 as effective additive (Table 1, entry 7 and entries 19–22). The con-
oxidant (Scheme 1, Equation 2).
trol experiments demonstrated that no reaction occurred in the
absence of either [{RuCl2(p-cymene)}2], K2S2O8 or KPF6 (Table 1,
entries 23–25).
Results and Discussion
Once the optimized conditions for the desired acyloxylation
reaction were established, the scope of the reaction with regard
to different carboxylic acids and azobenzenes was investigated
(Table 2). A broad range of aromatic acids with electron-donat-
ing and electron-withdrawing groups were all well tolerated
and gave the desired products in good yields. Aryl carboxylic
acids with electron-donating groups on the aryl ring resulted
in better yields of the desired products (3ad–3af unto 3ag–
Our initial goal was to determine the most suitable reaction
conditions for the coupling of azobenzene (1a) with benzoic
acid (2a) as model substrates (Table 1). The activities of different
oxidants in combination with [{RuCl2(p-cymene)}2] and KPF6
were first tested in CH3CN at 110 °C for 24 h. Screening a range
of oxidants showed that K2S2O8 performed the best among
other oxidants, including Ag2CO3, AgNO3, Cu(OAc)2·H2O and
TBHP (Table 1, entries 1–7). Different catalysts were also consid-
ered and the results showed that [{RuCl2(p-cymene)}2] was more
effective than the others (Table 1, entries 8–11). The reaction
was also monitored with different catalyst loadings, and the
Table 2. Scope of carboxylic acids for Ru-catalyzed C–H acyloxylation.[a]
Table 1. Optimization of the reaction conditions.[a]
Yield[b]
[%]
entry Catalyst
Oxidant
Solvent addidive
1
2
3
4
5
6
[{RuCl2(p-cymene)}2] Ag2CO3
[{RuCl2(p-cymene)}2] AgNO3
[{RuCl2(p-cymene)}2] Cu(OAc)2·H2O CH3CN
[{RuCl2(p-cymene)}2] TBHP
[{RuCl2(p-cymene)}2] (NH4)2S2O8
[{RuCl2(p-cymene)}2] Na2S2O8
CH3CN
CH3CN
KPF6
KPF6
KPF6
KPF6
KPF6
KPF6
0
0
0
0
11
31
CH3CN
CH3CN
CH3CN
[{RuCl2(p-
cymene)}2]
7
K2S2O8
CH3CN
KPF6
78
8
9
RuCl2(PPh3)2
RuCl3·H2O
Pd(OAC)2
PdCl2
K2S2O8
K2S2O8
K2S2O8
K2S2O8
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
DME
Toluene KPF6
PhCl
DCE
MeOH
DMF
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
KPF6
KPF6
–
–
KPF6
KPF6
19
11
27
0
76
27
17
23
48
0
0
37
0
0
0
10
11
12[c]
13
14
15
16
17
18
19
20
21
22
23
24
25
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
[{RuCl2(p-cymene)}2] K2S2O8
KPF6
KPF6
KPF6
KPF6
AgSbF6
K2CO3
PPh3
KOAc
–
0
0
0
–
K2S2O8
–
KPF6
KPF6
[{RuCl2(p-cymene)}2]
[a] 1a (0.3 mmol), 2a (0.6 mmol), catalyst (5 mol-%), oxidant (0.6 mmol),
solvent (1.5 mL) were stirred at 110 °C for 24 h. [b] Isolated yields of 3a.
[c] 7 mol-% of catalyst was used.
[a] 1a (0.3 mmol), 2 (0.6 mmol), Ru catalyst (5 mol-%), KPF6 (30 mol-%), K2S2O8
(2.0 equiv.), in acetonitrile (1.5 mL) at 110 °C for 24 h.
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
2
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
3ai). The yield of the acyloxyation product with this procedure
To gain accurate insight into the mechanism of the C–H
dropped when 4-nitro benzoic acid was used. Moreover, the acyloxylation reactions, a series of controlled experiments was
reaction was successful with 2-naphthoic acid affording the fa- performed. We ran the Ru-catalyzed C–H acyloxyation of azo-
vored product in moderate yield (3al). Fortunately 2-chloro- benzene with benzoic acid in the presence of BHT (2,6-di-tert-
nicotinic acid provided the desired product in moderate yield butyl-4-methylphenol) as a radical quencher, the reaction effi-
(3ao). Surprisingly, aliphatic carboxylic acids also gave the de- ciency did not change significantly (Scheme 2, Equation 1). Also,
sired products in good yields (3aa–3ac). After investigation of the reaction proceeded well when sodium benzoate was used
different carboxylic acids, the scope of substituted azobenzenes rather than benzoic acid (Scheme 2, Equation 2). These probes
was probed with benzoic acid (2a). As can be seen from Table 3, suggested that the reaction does not involve a radical pathway.
the azobenzenes with electron-rich para-substituents on aryl Based on the previous reports,[16, 29b] a possible mechanism for
ring represented better reactivity (3ba and 3bb unto 3bc and the Ru-catalyzed ortho-acyloxylation of azobenzens with
3bd). Moderate yields of the products were obtained when azo- benzoic acids is suggested in Scheme 3. Initially, azobenzene-
benzene derivatives with an alkyl or halogen group at the meta- induced C–H ruthenation from a ruthenium(II) biscarboxylate
position of the phenyl ring was used as the substrate (3be– 4[31] occurs preferentially at the ortho position of the aryl ring,
3bg). When the reaction was performed with unsymmetrical which leads to the formation of a five-membered metallacycle
azobenzene 4-(phenyldiazenyl)phenol, acyloxylation was oc- 5. Intermediate 5 could be oxidized into ruthenium(IV) species
curred at the less substituted aryl ring and to our surprise 3bj in the presence of K2S2O8. Finally, a reductive elimination yields
was obtained with high regioselectivity and any other isomer the desired product 3 and regenerates the catalytically active
was observed under the reaction conditions.[26]
ruthenium(II) species.
Table 3. Scope of azoarenes for Ru-catalyzed C–H acyloxylation.[a]
Scheme 2. Control reactions.
[a] 1 (0.3 mmol), 2a (0.6 mmol), Ru catalyst (5 mol-%), KPF6 (30 mol-%), K2S2O8
(2.0 equiv.), in acetonitrile (1.5 mL) at 110 °C for 24 h.
Scheme 3. Possible mechanism.
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
3
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
119 (28), 105 (100), 91 (58), 77 (37). C23H22N2O2 (358.43): calcd. C
77.07, H 6.19, N 7.82; found C 77.30, H 6.14, N 7.87.
Conclusion
In conclusion, we have illustrated and developed a highly regio-
and chemo-selective ortho-acyloxylation of azoarenes with aryl
and alkyl carboxylic acids in the presence of a ruthenium cata-
lyst in moderate to good yields. The catalytic reaction func-
tioned very impressively with disparate functional group-substi-
tuted carboxylic acids and azoarenes.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Methylbenzoate (3ad):
Orange solid, m.p: 99–101 °C. Yield: 85 % (87 mg). 1H NMR
(500 MHz, CDCl3): δ = 8.15 (d, J = 7.9 Hz, 2H), 7.78 (dd, J = 8.8, 1 Hz,
1H), 7.60 (d, J = 8.1 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 7.17 (d, J =
8.3 Hz, 3H), 7.15 (s, 1H), 2.48 (s, 3H), 2.46 (s, 3H), 2.36 (s, 3H); 13C
NMR (125 MHz, CDCl3): δ = 165.7, 150.9, 149.1, 144.3, 142.8, 141.9,
141.46, 130.4, 129.6, 129.3, 127.3, 123.9, 122.9, 117.5, 21.9, 21.6, 21.5;
MS (EI): m/z (%) = 344 (38) [M+], 225 (22), 167 (10), 149 (17), 119
(100), 91 (39), 65 (21). C22H20N2O2 (344.41): calcd. C 76.72, H 5.85,
N 8.13; found C 76.67, H 5.79, N 8.08.
Experimental Section
General Information: Solvents, Ruthenium catalyst, K2S2O8 and
aniline derivatives were purchased from Merck and Sigma. Other
reagents were purchased from commercial distributors and were
used without further purification. Azoarenes were synthesized ac-
cording to the literature.[32] Analytical thin layer chromatography
(TLC) was performed on precoated silica gel60 F254 plates. The
products were purified by preparative column chromatography on
silica gel (0.063–0.200 mm, Merck). 1H NMR and 13C NMR spectra
were recorded with a Bruker DRX 400 and 500 Advance instrument
in CDCl3 δ in ppm, J in Hz. Mass spectrometry was performed with
an Agilent 5975C VL MSD (ion source: EI+, 70 eV, 230 °C).
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl
4-Methoxybenzoate
1
(3ae): Orange solid, m.p: 103–106 °C. Yield: 87 % (93 mg). H NMR
(500 MHz, CDCl3): δ = 7.68 (d, J = 8.2 Hz, 1H), 7.40 (d, J = 0.9 Hz,
1H), 7.35 (d, J = 8.2 Hz, 2H), 7.31–7.28 (m, 1H), 7.07 (d, J = 7.9 Hz,
1H), 3.47 (s, 3 H ), 2.48 (s, 3H), 2.31 (s, 3H); 13C NMR (125 MHz,
CDCl3): δ = 165.3, 151.0, 149.1, 142.7, 142.0, 141.4, 132.5, 129.6,
127.2, 124.0, 122.9, 121.9, 117.5, 113.84, 55.5, 21.5, 21.4; MS (EI): m/z
(%) = 360 (12) [M+], 167 (21), 149 (31), 135 (100), 107 (21), 91 (27),
57 (28). C22H20N2O3 (360.41): calcd. C 73.32, H 5.59, N 7.77; found C
73.55, H 5.56, N 7.73.
General Procedure for the Synthesis of (E)-2-(Phenyldiazen-
yl)phenyl Benzoate: 10 mL microwave vial was charged with azo-
benzene derivatives (1 equiv., 0.3 mmol), carboxylic acid (2 equiv.,
0.6 mmol), Ru catalyst (5 mol-%), KPF6 (30 mol-%), K2S2O8
(2.0 equiv.), in acetonitrile (1.5 mL) at 110 °C for 24. The vial was
then sealed and immersed in an oil bath at 110 °C, for 24 h. After
this time, the mixture was cooled to room temperature and then
diluted with CH2Cl2 and filtered. The residue was purified by column
chromatography (n-hexane/EtOAc, 8:1) to yield the desired product.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Ethylbenzoate (3af):
Orange solid, m.p: 81–82 °C. Yield: 89 % (95 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.00 (d, J = 8.2 Hz, 2H), 7.93 (d, J = 8.2 Hz, 1H), 7.79 (dd,
J = 11.7, 7.8 Hz, 2H), 7.32 (d, J = 8.2 Hz, 2H), 7.26 (s, 1H), 7.14 (d,
J = 8.2 Hz, 1H), 7.05–7.01 (m, 2H), 2.66 (q, J = 7.2 Hz, 2H), 2.44 (s,
3H), 2.24 (s, 3H), 1.54 (s, t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3):
δ = 165.7, 150.8, 149.1, 141.4, 130.5, 130.4, 129.6, 128.1, 128.0, 127.3,
126.8, 123.9, 122.9, 29.1, 21.5, 21.4, 15.2; MS (EI): m/z (%) = 358 (43)
[M+], 239 (21), 133 (100), 105 (28), 91 (21), 79 (20). C23H22N2O2
(358.43): calcd. C 77.07, H 6.19, N 7.82; found C 77.34, H 6.23, N
7.87.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl
Isobutyrate
(3aa):
Orange solid, m.p: 71–73 °C. Yield: 78 % (69 mg). 1H NMR (500 MHz,
CDCl3): δ = 7.76 (d, J = 8.2 Hz, 2H), 7.67 (d, J = 8.3 Hz, 1H), 7.30 (d,
J = 8.1 Hz, 2H), 7.15 (dd, J = 8.2, 1.8 Hz, 1H), 7.05 (d, J = 1.4 Hz, 1H),
2.96 (H, J = 5 Hz,1H), 2.45 (s, 6H), 1.41 (d, J = 7.1 Hz, 3H), 1.40 (d,
J = 6.9 Hz, 3H). 13C NMR (125 MHz, CDCl3): δ = 165.5, 154.0, 141.5,
132.4, 129.9, 129.6, 127.2, 122.9, 122.1, 34.2, 21.5, 21.5, 16.1; MS (EI):
m/z (%) = 296 (49) [M+], 249 (57), 226 (81), 151 (51), 135 (73), 119
(38), 107 (53), 91 (100), 77 (31). C18H20N2O2 (296.36): calcd. C 72.95,
H 6.80, N 9.45; found C 72.71, H 6.84, N 9.51.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Chlorobenzoate (3ag):
Orange solid, m.p: 89–90 °C. Yield: 79 % (86 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.12 (d, J = 8.3 Hz, 1H), 7.92 (d, J = 8.3 Hz, 1H), 7.49–
7.43 (m, 3H), 7.10 (s, 1H), 6.98–6.94 (m, 4H), 2.48 (s, 3H), 2.26 (s, 3H);
13C NMR (125 MHz, CDCl3): δ = 164.4, 150.9, 145.1, 142.1, 140.1,
131.8, 129.5, 129.1, 129.0, 128.9, 127.9, 122.5, 122.3, 121.6, 121.4,
21.6, 21.4; MS (EI): m/z (%) = 367 (11) [M + 2], 365 (5) [M+], 261 (14),
139 (100), 119 (21), 111 (37), 91 (28). C21H17ClN2O2 (364.83): calcd.
C 69.14, H 4.7, N 7.68; found C 69.41, H 4.90, N 7.61.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 2-Phenylacetate (3ab):
Orange oil. Yield: 71 % (73 mg). 1H NMR (500 MHz, CDCl3): δ = 7.72
(d, J = 8.2 Hz, 1H), 7.58 (d, J = 8.3 Hz, 2H), 7.47–7.45 (m, 2H), 7.39–
7.34 (m, 3H), 7.25 (d, J = 8.2 Hz, 2H), 7.14 (dd, J = 8.3, 1.8 Hz, 1H),
7.04 (d, J = 1.7 Hz, 1H), 3.99 (s, 2H), 2.45 (s, 3H), 2.43 (s, 3H). 13C
NMR (125 MHz, CDCl3): δ = 168.0, 154.0, 148.8, 137.1, 132.2, 130.5,
130.4, 130.4, 129.9, 129.6, 127.5, 127.3, 126.2, 123.6, 122.9, 122.2,
117.1, 116.5, 114.4, 40.4, 21.5, 21.4; MS (EI): m/z (%) = 342 (21) [M+],
265 (15), 225 (31), 117 (41), 105 (100), 91 (64), 77 (47). C22H20N2O2
(344.41): calcd. C 76.72, H 5.85, N 8.13; found C 76.89, H 5.89, N
8.17.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Bromobenzoate (3ah):
Orange solid, m.p: 95–96 °C. Yield: 72 % (87 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.12 (d, J = 8.6 Hz, 2H), 7.78 (d, J = 8.2 Hz, 1H), 7.69–
7.67 (m, 2H), 7.58–7.54 (m, 2H), 7.20–7.16 (m, 4H), 2.46 (s, 3H), 2.37
(s, 3H). 13C NMR (125 MHz, CDCl3): δ = 165.8, 150.9, 149.1, 142.8,
141.9, 141.5, 138.4, 134.3, 130.9, 129.6, 129.5, 128.5, 127.5, 127.4,
123.9, 122.9, 117.5, 21.5, 21.4; MS (EI): m/z (%) = 409 (67) [M + 1],
408 (67) [M+], 317 (15), 289 (51), 183 (100), 149 (31), 119 (28), 91
(57). C21H17BrN2O2 (409.28): calcd. C 61.63, H 4.19, N 6.84; found C
61.38, H 4.14, N 6.87.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 2-(o-Tolyl)acetate (3ac):
Yellow solid, m.p: 99–100 °C. Yield: 73 % (77 mg). 1H NMR (500 MHz,
CDCl3): δ = 7.71 (d, J = 8.2 Hz, 1H), 7.63 (d, J = 8.2 Hz, 2H), 7.50 (d,
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Fluorobenzoate (3ai):
Orange solid, m.p: 91–93 °C. Yield: 69 % (71 mg). 1H NMR (500 MHz,
J = 8.2 Hz, 1H), 7.38 (d, J = 7.3 Hz, 1H), 7.28–7.24 (m, 4H), 7.13 (d, CDCl3): δ = 8.28 (dd, J = 8.5, 5.4 Hz, 2H), 7.78 (d, J = 8.1 Hz, 1H),
J = 8.3 Hz, 1H), 7.04 (s, 1H), 3.73 (s, 2H), 2.46 (s, 3H), 2.43(s, 3H), 2.42
7.57 (d, J = 8.0 Hz, 2H), 7.24–7.08 (m, 6H), 2.46 (s, 3H), 2.36 (s, 3H);
(s, 3H); 13C NMR (125 MHz, CDCl3): δ = 169.8, 151.0, 148.8, 142.6, 13C NMR (125 MHz, CDCl3): δ = 164.7, 150.9, 148.9, 142.9, 141.7 (d,
142.1, 137.1, 132.2, 130.5, 130.4, 130.4, 129.9, 129.6, 127.5, 127.3, J = 13.5 Hz), 133.0 (d, J = 9.3 Hz), 129.6, 127.5, 125.8, 123.8, 122.9,
126.2, 123.6, 122.9, 122.2, 117.1, 39.0, 21.5, 21.4, 19.8; MS (EI): m/z 117.7, 115.8 (d, J = 21.8 Hz, 1H), 21.6, 21.5; MS (EI): m/z (%) = 348
(%) = 356 (7) [M+], 242 (73), 226 (98), 198 (21), 151 (38), 135 (61),
(62) [M+], 229 (57), 167 (21), 149 (38), 123 (100), 91 (43), 57 (18).
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
4 © 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
C21H17FN2O2 (348.37): calcd. C 72.40, H 4.92, N 8.04; found C 72.14,
H 4.86, N 8.11.
(100). C20H16ClN3O2 (365.81): calcd. C 65.67, H 4.41, N 11.49; found
C 65.76, H 4.40, N 11.46.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl Benzoate (3ba):[26]
Orange solid, m.p: 91–93 °C. Yield: 78 % (77 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.29 (dd, J = 8.3, 1.4 Hz, 2H), 7.82 (d, J = 8.7 Hz, 1H),
7.70 (t, J = 7.4 Hz, 1H), 7.61 (d, J = 8.2 Hz, 2H), 7.59–7.54 (m, 2H),
7.23–7.17 (m, 4H), 2.50 (s, 3H), 2.39 (s, 3H); 13C NMR (125 MHz,
CDCl3): δ = 165.7, 150.9,149.0, 142.8, 141.5, 133.5, 130.4, 129.6,
129.5, 129.3, 128.6, 127.4, 123.9, 122.9, 117.6, 21.6, 21.5; MS (EI): m/z
(%) = 330 (60) [M+], 211 (51), 119 (24), 105 (100), 91 (39), 77 (45).
C21H18N2O2 (330.38): calcd. C 76.34, H 5.49, N 8.48; found C 76.57,
H 4.46, N 8.53.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl[1,1′-biphenyl]-4-carb-
oxylate (3aj): Brown oil. Yield: 77 % (93 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.35 (d, J = 8.3 Hz, 1H), 7.83–7.77 (m, 3H), 7.72 (d, J =
7.9 Hz, 2H), 7.64 (d, J = 8.2 Hz, 2H), 7.54 (t, J = 7.6 Hz, 2H), 7.46 (t,
J = 7.4 Hz, 1H), 7.22–7.10 (m, 3H), 2.49 (s, 3H), 2.37 (s, 3H); 13C NMR
(125 MHz, CDCl3): δ = 165.4, 151.0, 149.0, 146.2, 142.7, 141.4, 140.0,
130.9, 129.6, 129.0, 128.3, 127.3, 127.2, 123.9, 122.9, 117.6, 21.5, 21.4;
MS (EI): m/z (%) = 406 (8) [M+], 348 (21), 330 (35), 225 (33), 211 (47),
149 (31), 105 (100), 91 (49), 77 (53). C27H22N2O2 (406.48): calcd. C
79.78, H 5.46, N 6.89; found C 79.98, H 5.49, N 6.91.
(E)-5-Ethyl-2-[(4-ethylphenyl)diazenyl]phenyl Benzoate (3bb):
Brown solid, m.p: 87–88 °C. Yield: 81 % (86 mg). H NMR (500 MHz,
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 4-Nitrobenzoate (3ak):
Orange solid, m.p: 109–110 °C. Yield: 67 % (75 mg). 1H NMR
(400 MHz, CDCl3): δ = 8.47–8.40 (m, 4H), 7.84 (d, J = 8.2 Hz, 1H),
7.58 (d, J = 8.0 Hz, 2H), 7.26–7.18 (m, 4H), 2.51 (s, 3H), 2.39 (s, 3H);
13C NMR (125 MHz, CDCl3): δ = 163.8, 150.8, 148.4, 143.0, 141.9,
141.5, 135.0, 131.5, 129.7, 127.9, 123.8, 123.5, 122.8, 118.0, 21.6, 21.5;
MS (EI): m/z (%) = 357 (100) [M+], 284 (19), 256 (43), 210 (41), 150
(38), 119 (31), 104 (28), 91 (78). C21H17N3O4 (375.38): calcd. C 67.19,
H 4.56, N 11.19; found C 67.36, H 4.59, N 11.12.
1
CDCl3): δ = 8.27 (d, J = 7.7 Hz, 1H), 7.81 (d, J = 8.2 Hz, 1H), 7.67 (t,
J = 7.5 Hz, 1H), 7.54 (t, J = 7.7 Hz, 2H), 7.21 (d, J = 7.8 Hz, 2H), 7.18
(d, J = 8.0 Hz, 2H), 2.76 (q, J = 7.6 Hz, 2H), 2.65 (q, J = 7.6 Hz, 2H),
1.31 (t, J = 7.6 Hz, 3H), 1.22 (t, J = 7.6 Hz, 3H); 13C NMR (125 MHz,
CDCl3): δ = 165.9, 151.1, 149.1, 147.7, 135.4, 133.4, 130.3, 129.6,
128.5, 128.3, 126.1, 123.0, 122.5, 117.7, 28.8, 28.7, 15.0, 14.95; MS
(EI): m/z (%) = 358 (37) [M+], 253 (31), 225 (68), 210 (27), 105 (100),
77 (33). C23H22N2O2 (358.43): calcd. C 77.07, H 6.19, N 7.82; found C
77.29, H 6.17, N 7.86.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 2-Naphthoate (3al):
Brown solid, m.p: 101–103 °C. Yield: 65 % (74 mg). 1H NMR
(500 MHz, CDCl3): δ = 8.89 (d, J = 1.6 Hz, 1H), 8.28 (dd, J = 8.5,
1.7 Hz, 1H), 8.05 (d, J = 8.2 Hz, 1H), 8.01–7.97 (m, 2H ),7.84 (d, J =
8.2 Hz, 1H), 7.68–7.61 (m, 4H), 7.29–7.23 (m, 3H), 7.13 (d, J = 8.1 Hz,
2H), 2.51 (s, 3H), 2.34 (s, 3H); 13C NMR (125 MHz, CDCl3): δ = 165.7,
151.0, 149.1, 141.5, 135.9, 132.6, 132.1, 129.6, 129.2, 128.5, 128.4,
127.9, 127.4, 126.8, 126.8, 125.7, 123.9, 122.9, 122.7, 117.6, 21.5, 21.4;
MS (EI): m/z (%) = 380 (61) [M+], 261 (23), 105 (100), 127 (41), 91
(18). C25H20N2O2 (380.44): calcd. C 78.93, H 5.30, N 7.36; found C
78.82, H 5.36, N 7.30.
(E)-5-Chloro-2-[(4-chlorophenyl)diazenyl]phenyl Benzoate
(3bc):[26] Orange solid, m.p: 138–139 °C. Yield: 71 % (78 mg). 1H
NMR (500 MHz, CDCl3): δ = 8.24 (d, J = 7.9 Hz, 2H), 7.87 (d, J =
8.8 Hz, 2H), 7.69 (t, J = 7.6 Hz, 1H), 7.61 (d, J = 8.5 Hz, 2H), 7.55 (t,
J = 7.7 Hz, 1H), 7.49 (d, J = 8.4 Hz, 2H), 7.43 (s, 1H), 7.33 (d, J =
8.5 Hz, 2H); 13C NMR (125 MHz, CDCl3): δ = 165.1, 151.0, 149.7,
142.5, 137.5, 137.2, 133.9, 130.4, 129.4, 128.7, 127.0, 124.2, 124.1,
118.8; MS (EI): m/z (%) = 371 (6) [M + 1], 370 (11) [M +], 250 (41),
152 (18), 139 (37), 111 (100), 75 (46). C19H12Cl2N2O2 (371.22): calcd.
C 61.47, H 3.26, N 7.55; found C 61.32, H 3.38, N 7.58.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 3-Methoxybenzoate
(3am): Orange solid, m.p: 74–75 °C. Yield: 71 % (76 mg). 1H NMR
(500 MHz, CDCl3): δ = 7.87 (d, J = 7.6 Hz, 1H), 7.79 (d, J = 8.5 Hz,
1H), 7.75 (s, 1H), 7.60 (d, J = 8.0 Hz, 2H), 7.44 (t, J = 8.0 Hz, 1H),
7.20–7.15 (m, 5H), 3.88 (s, 3H), 2.46 (s, 3H), 2.36 (s, 3H); 13C NMR
(125 MHz, CDCl3): δ = 159.7, 150.9, 142.8, 141.8, 141.6, 130.8, 129.6,
127.4, 123.8, 122.9, 121.1, 120.4, 117.6, 114.4, 55.6, 29.7, 21.6; MS
(EI): m/z (%) = 360 (51) [M+], 241 (32), 135 (100), 107 (27), 91 (26),
77 (21). C22H20N2O3 (360.41): calcd. C 73.32, H 5.59, N 7.77; found C
73.47, H 5.61, N 7.72.
(E)-5-Bromo-2-[(4-bromophenyl)diazenyl]phenyl Benzoate
(3bd):[26] Orange solid, m.p: 145–146 °C. Yield: 69 % (94 mg). 1H
NMR (500 MHz, CDCl3): δ = 8.23 (d, J = 7.7 Hz, 2H), 7.76 (d, J =
8.6 Hz, 1H), 7.69 (t, J = 7.5 Hz, 1H), 7.57 (d, J = 8.8 Hz, 2H), 7.55–
7.52 (m, 4H), 7.49 (d, J = 8.6 Hz, 2H); 13C NMR (125 MHz, CDCl3): δ =
165.1, 151.3, 149.7, 142.8, 134.0, 132.3, 130.4, 130.0, 128.8, 128.8,
127.0, 126.1, 125.9, 124.5, 118.9; MS (EI): m/z (%) = 462 (5) [M +
2],461 (4) [M + 1], 460 (10) [M+], 305 (11), 303 (15), 105 (100), 77
(47). C19H12Br2N2O2 (460.12): calcd. C 49.60, H 2.63, N 6.09; found C
49.84, H 2.66, N 6.13.
(E)-4-Methyl-2-(m-tolyldiazenyl)phenyl Benzoate (3be):[26] Dark
orange solid, m.p: 80–83 °C. Yield: 68 % (67 mg). 1H NMR (500 MHz,
CDCl3): δ = 8.27 (d, J = 7.2 Hz, 2H), 7.67–7.64 (m, 2H), 7.54 (t, J =
7.7 Hz, 3H), 7.45 (s, 1H), 7.35 (d, J = 2.1 Hz, 1H), 7.28–7.24 (m, 2H),
7.20 (d, J = 7.5 Hz, 1H), 2.45 (s, 3H), 2.25 (s, 3H); 13C NMR (125 MHz,
CDCl3): δ = 165.8, 152.8, 147.3, 143.3, 138.8, 136.5, 133.5, 132.7,
131.9, 130.4, 128.8, 128.6, 123.1, 123.0, 120.9, 117.8, 21.2, 21.1; MS
(EI): m/z (%) = 330 (51) [M+],239 (11), 211 (43), 105 (100), 91 (32),
77 (41). C21H18N2O2 (330.38): calcd. C 76.34, H 5.49, N 8.48; found C
76.61, H 5.54, N 8.44.
(E)-5-Methyl-2-(p-tolyldiazenyl)phenyl 3-Methylbenzoate (3an):
Brown solid, m.p: 71–72 °C. Yield: 67 % (69 mg). H NMR (500 MHz,
1
CDCl3): δ = 8.08 (d, J = 4.4 Hz, 1H), 8.06 (s, 1H), 7.78 (d, J = 8.6 Hz,
1H), 7.60 (d, J = 8.0 Hz, 2H), 7.47 (d, J = 7.7 Hz, 1H), 7.42 (t, J =
7.7 Hz, 1H), 7.17–7.14 (m, 4H), 2.46 (s, 6H), 2.36 (s, 3H); 13C NMR
(125 MHz, CDCl3): δ = 164.9, 150.9, 148.8, 142.9, 141.7, 141.7, 132.0,
131.8, 129.7, 128.8, 128.5, 127.6, 123.7, 122.9, 117.7, 29.73, 21.6, 21.5;
MS (EI): m/z (%) = 344 (53) [M+], 255 (37), 149 (18), 119 (100), 91
(49), 65 (28). C22H20N2O2 (344.41): calcd. C 76.72, H 5.85, N 8.13;
found C 76.53, H 5.88, N 8.09.
(E)-2-(Phenyldiazenyl)phenyl 2-Chloronicotinate (3ao): Orange
(E)-4-Ethyl-2-[(3-ethylphenyl)diazenyl]phenyl Benzoate (3bf):
1
oil. Yield: 69 % (75 mg). H NMR (500 MHz, CDCl3): δ = 8.54 (d, J = Orange oil. Yield: 69 % (73 mg). 1H NMR (500 MHz, CDCl3): δ = 8.25
2.4 Hz, 1H), 8.19 (dd, J = 7.7, 2.0 Hz, 1H), 7.83–7.76 (m, 2H), 7.36–
7.28 (m, 4H), 7.19 (d, J = 8.0 Hz, 1H), 7.15 (d, J = 7.5 Hz, 1H), 2.40
(s, 3H), 2.37 (s, 3H); 13C NMR (125 MHz, CDCl3): δ = 162.9, 151.9,
(d, J = 7.7 Hz, 2H), 7.70 (s, 1H), 7.66 (t, J = 7.5 Hz, 1H), 7.56–7.51 (m,
3H), 7.48 (s, 1H), 7.39 (dd, J = 8.2, 2.1 Hz, 1H), 7.31–7.28 (m, 2H),
7.22 (d, J = 7.6 Hz, 1H), 2.76 (q, J = 7.8 Hz, 2H), 2.55 (q, J = 7.6 Hz,
140.2, 132.8, 130.7, 130.1, 130.0, 128.1, 127.6, 125.6, 122.4, 122.3, 2H), 1.32 (t, J = 7.6 Hz, 3H), 1.10 (t, J = 7.6 Hz, 3H); 13C NMR
122.0, 122.0, 121.1, 118.3, 117.4; MS (EI): m/z (%) = 365 (17) [M+],
(125 MHz, CDCl3): δ = 165.2, 152.9, 147.4, 142.6, 138.9, 138.6, 133.5,
242 (21), 191 (57), 151 (23), 123 (29), 107 (65), 91 (85), 71 (83), 57
131.5, 130.9, 130.4, 128.8, 128.6, 123.1, 121.5, 121.3, 116.7, 28.9, 28.5,
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
5
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
15.5, 15.30. MS (EI): m/z (%) = 358 (41) [M+], 253 (11), 225 (58), 210
(12), 105 (100), 77 (43). C23H22N2O2 (358.43): calcd. C 77.07, H 6.19,
N 7.82; found C 77.40, H 6.16, N 7.77.
[3]
[4]
[5]
a) M. R. Banghart, A. Mourot, D. L. Fortin, J. Z. Yao, R. H. Kramer, D.
Trauner, Angew. Chem. Int. Ed. 2009, 48, 9097; Angew. Chem. 2009, 121,
9261; b) Y. Kim, J. A. Phillips, H. Liu, H. Kang, W. Tan, Proc. Natl. Acad. Sci.
USA 2009, 106, 6489.
a) E. Ishow, C. Bellaïche, L. Bouteiller, K. Nakatani, J. A. Delaire, J. Am.
Chem. Soc. 2003, 125, 15744; b) I. Papagiannouli, K. Iliopoulos, D. Gindre,
B. Sahraoui, O. Krupka, V. Smokal, A. Kolendo, S. Couris, Chem. Phys. Lett.
2012, 554, 107.
a) J. L. Jenkins, R. Shapiro, Biochemistry 2003, 42, 6674; b) G. Latham,
M. M. Winkler, B. L. Pasloske, W. A. Kudlicki, U. S. Patent 20050014169 A1
20050120, 2005; c) S. C. Hopkins, R. D. Vale, I. D. Kuntz, Biochemistry
2000, 39, 2805; d) R. Shapiro, J. L. Jenkins, G. J. Latham, Patent WO 2004/
076640 A2 20040910, 2004.
(E)-4-Chloro-2-[(3-chlorophenyl)diazenyl]phenyl Benzoate
1
(3bg): Orange solid, m.p: 131–132 °C. Yield: 63 % (69 mg). H NMR
(500 MHz, CDCl3): δ = 8.25 (d, J = 7.7 Hz, 2H), 7.86 (d, J = 2.6 Hz,
1H), 7.69 (t, J = 7.5 Hz, 1H), 7.68–7.61 (m, 1H), 7.57–7.52 (m, 3H),
7.39–7.32 (m, 3H); 13C NMR (125 MHz, CDCl3): δ = 165.4, 153.2,
148.3, 143.9, 135.1, 134.0, 132.4, 132.2, 131.4, 130.4, 130.1, 128.8,
124.8, 122.7, 122.1, 117.7; MS (EI): m/z (%) = 372 (4) [M + 2], 370 (7)
[M+], 149 (11), 105 (100), 77 (31). C19H12Cl2N2O2 (371.22): calcd. C
61.47, H 3.26, N 7.55; found C 61.73, H 3.24, N 7.51.
[6]
[7]
W. Wenhu, L. Tingting, R. Xinxia, S. Yingjun, Z. Xiujie; CN-102424661-A,
2012.
(E)-2-[(3,4-Dimethylphenyl)diazenyl]-4,5-dimethylphenyl
Benzoate (3bh): Yellow solid, m.p: 99–101 °C. Yield: 74 % (55 mg).
1H NMR (500 MHz, CDCl3): δ = 8.27 (d, J = 7.7 Hz, 2H), 7.67–7.64
(m, 1H), 7.53 (t, J = 7.8 Hz, 3H), 7.45 (dd, J = 8.0, 2.1 Hz, 1H), 7.41
(d, J = 2.0 Hz, 1H), 7.16 (s, 1H), 7.11 (d, J = 8.0 Hz, 1H), 2.36 (s, 3H),
2.34 (s, 3H), 2.25 (s, 3H), 2.14 (s, 3H); 13C NMR (125 MHz, CDCl3): δ =
165.8, 151.4, 147.1, 141.3, 140.0, 134.9, 133.3, 130.3, 130.0, 128.8,
128.5, 124.5, 124.1, 123.4, 121.0, 118.3, 20.0, 19.7, 19.6, 19.4; MS (EI):
m/z (%) = 358 (73) [M+], 253 (21), 225 (98), 210 (13), 105 (100), 77
(32). C23H22N2O2 (358.43): calcd. C 77.07, H 6.19, N 7.82; found C
77.36, H 6.23, N 7.87.
a) L. Górecki, W. Tomczak, CHEMIK 2012, 66, 1298; ##65## b) M. Ono, Y.
Wada, Y. Wu, R. Nemori, Y. Jinbo, H. Wang, K. M. Lo, N. Yamaguchi, B.
Brunkhorst, H. Otomo, J. Wesolowski, J. C. Way, I. Itoh, S. Gillies, L. B.
Chen, Nat. Biotechnol. 1997, 15, 343; c) H. Xu, X. Zeng, Bioorg. Med. Chem.
Lett. 2010, 20, 4193.
[8]
[9]
C. Kocher, C. Weder, P. Smith, Adv. Funct. Mater. 2003, 13, 427.
a) S. Miyamura, H. Tsurugi, T. Satoh, M. Miura, J. Organomet. Chem. 2008,
693, 2438; b) E. Drug, M. Gozin, J. Am. Chem. Soc. 2007, 129, 13784; c)
C. Zhang, N. Jiao, Angew. Chem. Int. Ed. 2010, 49, 6174; Angew. Chem.
2010, 122, 6310; d) Y. Takeda, S. Okumura, S. Minakata, Angew. Chem.
Int. Ed. 2012, 51, 7804; Angew. Chem. 2012, 124, 7924; e) S. Cai, H. Rong,
X. Yu, X. Liu, D. Wang, W. He, Y. Li, ACS Catal. 2013, 3, 478; f) Y. Zhu, Y.
Shi, Org. Lett. 2013, 15, 1942.
T. H. Long Nguyen, N. Gigant, D. Joseph, ACS Catal. 2018,, 1546.
a) Z. Y. Li, D. D. Li, G. W. Wang, J. Org. Chem. 2013, 78, 10414; b) H. J. Li,
P. H. Li, P. H. Tan, L. Wang, Chem. Eur. J. 2013, 19, 14432.
H. J. Li, P. H. Li, L. Wang, Org. Lett. 2013, 15, 620.
a) F. Xiong, C. Qian, D. E. Lin, W. Zeng, X. X. Lu, Org. Lett. 2013, 15, 5444;
b) H. Song, D. Chen, C. Pi, X. Cui, Y. Wu, J. Org. Chem. 2014, 79, 2955.
G. Hong, D. Mao, S. Wu, L. Wang, J. Org. Chem. 2014, 79, 10629.
H. Deng, H. Li, L. Wang, Org. Lett. 2015, 17, 2450.
J. Hubrich, T. Himmler, L. Rodefeld, L. Ackermann, ACS Catal. 2015, 5,
(E)-2-(Phenyldiazenyl)phenyl Benzoate (3bi):[26] Orange solid,
1
m.p: 94–95 °C. Yield: 71 % (63 mg). H NMR (500 MHz, CDCl3): δ =
[10]
[11]
8.27 (d, J = 7.2 Hz, 2H), 7.89 (dd, J = 8.4, 1.6 Hz, 1H), 7.71 (dd, J =
7.8, 1.9 Hz, 2H), 7.67 (d, J = 7.4 Hz, 1H), 7.57–7.52 (m, 3H), 7.41–7.37
(m, 5H); 13C NMR (125 MHz, CDCl3): δ = 165.3, 149.2, 138.1, 133.5,
132.0, 131.2, 130.3, 129.5, 128.9, 128.6, 126.5, 123.5, 123.0, 122.9,
117.9; MS (EI): m/z (%) = 302 (43) [M+], 224 (31), 182 (47), 121 (24),
105 (100), 77 (63). C19H14N2O2 (302.33): calcd. C 75.48, H 4.67, N
9.27; found C 75.59, H 4.65, N 9.30.
[12]
[13]
[14]
[15]
[16]
(E)-2-[(4-Hydroxyphenyl)diazenyl]phenyl Benzoate (3bj):
Orange solid, m.p: 112–113 °C. Yield: 53 % (50 mg). 1H NMR
(300 MHz, CDCl3): δ = 8.43 (s, 1H), 8.33–8.27 (m, 2H), 8.19 (d, J =
6.9 Hz, 1H), 7.90 (td, J = 7.4, 1.5 Hz, 1H), 7.84–7.74 (m, 3H), 7.72–
7.64 (m, 1H), 7.58 (d, J = 8.1 Hz, 2H), 7.46 (dd, J = 7.6, 1.5 Hz, 1H),
7.09 (d, J = 8.0 Hz, 2H); 13C NMR (125 MHz, CDCl3): δ = 165.6, 150.9,
149.0, 142.8, 133.5, 130.3, 129.5, 129.2, 128.5, 127.4, 123.8, 122.9,
117.5; MS (EI): m/z (%) = 318 (16) [M+], 243 (34), 225 (41), 182 (57),
105 (100), 77 (74). C19H14N2O3 (318.33): calcd. C 71.69, H 4.43, N
8.80; found C 71.83, H 4.40, N 8.85.
4089.
[17]
a) T. Wang, W. Zhou, H. Yin, J. A. Ma, N. Jiao, Angew. Chem. Int. Ed. 2012,
51, 10823; Angew. Chem. 2012, 124, 10981; b) L. Chen, E. Shi, Z. Liu, S.
Chen, W. Wei, H. Li, K. Xu, X. Wan, Chem. Eur. J. 2011, 17, 4085; c) X.
Wang, Y. Lu, H. X. Dai, J. Q. Yu, J. Am. Chem. Soc. 2010, 132, 12203; d) H.
Wanga, W. Wena, H. B. Zoub, F. Chenga, A. Alia, L. Shic, H. Y. L, C. K.
Changd, New J. Chem. 2017, 41, 3508; e) V. S. Thirunavukkarasu, S. I.
Kozhushkov, L. Ackermann, Chem. Commun. 2014, 50, 29; f) W. Liu, L.
Ackermann, Org. Lett. 2013, 15, 3484; g) F. Yang, K. Rauch, K. Kettelhoit,
L. Ackermann, Angew. Chem. Int. Ed. 2014, 53, 11285; Angew. Chem.
2014, 126, 11467; h) V. S. Thirunavukkarasu, L. Ackermann, Org. Lett.
2012, 14, 6206; i) V. S. Thirunavukkarasu, J. Hubrich, L. Ackermann, Org.
Lett. 2012, 14, 4210; j) Y. H. Sun, T. Y. Sun, Y. D. Wu, X. Zhang, Y. Rao,
Chem. Sci. 2016, 7, 2229.
Acknowledgments
We gratefully acknowledge the financial support from the Re-
search Council of the University of Tehran and the Iran National
Science Foundation (INSF, no. 96008622). We thank Dr Karol
Gajewski, Natural Resources Canada, for helpful comments on
this work.
[18]
[19]
Z. Yin, X. Jiang, p. Sun, J. Org. Chem. 2013, 78, 10002.
K. Seth, M. Nautiyal, P. Purohit, N. Parikh, A. K. Chakraborti, Chem. Com-
mun. 2015, 51, 191.
T. H. L. Nguyen, N. Gigant, S. D. Cochin, D. Joseph, J. Org. Chem. 2016,
81, 1850.
S. Moghimi, M. Mahdavi, A. Shafiee, A. Foroumadi, Eur. J. Org. Chem.
2016, 2016, 3282 and references cited therein.
C. Chen, Y. Pan, H. Zhao, X. Xu, J. Xu, Z. Zhang, S. Xi, L. Xua, H. Li, Org.
Chem. Front. 2018, 5, 415.
W. Yu, J. Chen, K. Gao, Z. Liu, Y. Zhang, Org. Lett. 2014, 16, 4870.
a) X. J. Zheng, B. R. Song, B. Xu, Eur. J. Org. Chem. 2010, 2010, 4376; b)
C. J. Hu, X. H. Zhang, Q. P. Ding, T. Lv, S. P. Ge, P. Zhong, Tetrahedron Lett.
2012, 53, 2465; c) S. R. Patpi, B. Sridhar, P. R. Tadikamalla, S. Kantevari,
RSC Adv. 2013, 3, 10251; d) Z. C. Wang, C. X. Kuang, Adv. Synth. Catal.
2014, 356, 1549; e) S. K. Santra, A. Banerjee, N. Khatun, B. K. Patel, Eur. J.
Org. Chem. 2015, 2015, 350; f) G. W. Wang, T. T. Yuan, X. L. Wu, J. Org.
Chem. 2008, 73, 4717.
[20]
[21]
[22]
Keywords: C–H activation · Acyloxylation · Azoarenes ·
Ruthenium · Homogeneous catalysis
[23]
[24]
[1] a) K. Hunger, Industrial Dyes: Chemistry, Properties, Applications; Wiley-
VCH, Weinheim, 2003; b) A. Bafana, S. S. Devi, T. Chakrabarti, Environ.
Rev. 2011, 19, 350; c) N. DiCesare, J. R. Lakowicz, Org. Lett. 2001, 3, 3891.
[2] a) G. S. Kumar, D. C. Neckers, Chem. Rev. 1989, 89, 1915; b) A. J. Harvey,
A. D. Abell, Tetrahedron 2000, 56, 9763; c) F. Puntoriero, P. Ceroni, V.
Balzani, G. Bergamini, F. Voegtle, J. Am. Chem. Soc. 2007, 129, 10714.
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
6
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
[25] a) A. R. Dick, K. L. Hull, M. S. Sanford, J. Am. Chem. Soc. 2004, 126, 2300;
b) F. Tato, A. G. Domínguez, D. J. Cardenas, Organometallics 2013, 32,
7487.
[30] a) T. Sarkar, S. Pradhan, T. Punniyamurthy, J. Org. Chem. 2018, 83, 6444;
b) P. B. De, S. Banerjee, S. Pradhan, T. Punniyamurthy, Org. Biomol. Chem.
2018, 16, 5889.
[26] C. Qian, D. Lin, Y. Deng, X. Q. Zhang, H. Jiang, G. Miao, X. Tanga, W. Zeng,
[31] L. Ackermann, P. Novák, R. Vicente, N. Hofmann, Angew. Chem. Int. Ed.
2009, 48, 6045; Angew. Chem. 2009, 121, 6161.
Org. Biomol. Chem. 2014, 12, 5866.
[27] F. Wang, Q. Hu, C. Shu, Z. Lin, D. Min, T. Shi, W. Zhang, Org. Lett. 2017,
19, 3636.
[32] M. Li, Y. Ye, ChemCatChem 2015, 7, 4137.
[28] W. Wang, F. Luo, S. Zhang, J. Cheng, J. Org. Chem. 2010, 75, 2415.
[29] a) K. Raghuvanshi, K. Rauch, L. Ackermann, Chem. Eur. J. 2015, 21, 1790;
b) K. Raghuvanshi, D. Zell, L. Ackermann, Org. Lett. 2017, 19, 1278.
Received: October 12, 2018
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
7
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
C–H Activation
E. Kianmehr,*
S. Bahrami Nasab .............................. 1–8
Ruthenium-Catalyzed Regioselec-
tive Direct Ortho-Acyloxylation of
Azoarenes with Carboxylic Acids via
C–H Bond Activation
A ruthenium-catalyzed cross-coupling ortho-acyloxylated azoarenes were ob-
reaction of azoarenes with carboxylic tained directly in moderate to good
acids has been developed. A series of yields.
Twiiter: Ebrahim Kianmehr and Sepideh Bahrami Nasab report on a ruthenium-catalyzed cross-coupling reaction of
azoarenes with carboxylic acids. Read more in their communication.
Share your work on social media! The European Journal of Organic Chemistry has added Twitter as a means to promote
your article. Twitter is an online microblogging service that enables its users to send and read text-based messages of up
to 140 characters, known as “tweets”. Please check the pre-written tweet in the galley proofs for accuracy. Should you or
your institute have a Twitter account, please let us know the appropriate username (i.e., @accountname), and we will do
our best to include this information in the tweet. This tweet will be posted to the journal’s Twitter account @EurJOC (follow
us!) upon online publication of your article, and we recommend you to repost (“retweet”) it to alert other researchers
about your publication.
DOI: 10.1002/ejoc.201801545
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
8
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim