Highly efficient AgNO3-catalyzed approach to 2-(benzo[d]azol-2-yl)phenols from salicylaldehydes with 2-aminothiophenol, 2-aminophenol and benzene-1,2-diamine

Article abstract of DOI:10.1002/aoc.4284

A new, convenient and efficient AgNO₃-catalyzed strategy for the preparation of 2-(benzo[d]azol-2-yl)phenol derivatives in good to excellent yields (63–98%) is described. The reaction proceeds via condensation/intramolecular nucleophilic addition/oxidation process between substituted salicylaldehydes and 2-aminothiophenol, 2-aminophenol or benzene-1,2-diamine under mild reaction conditions. Notably, this reaction utilizes cheap AgNO₃ as a readily available and low-cost benign oxidant at low catalyst loadings with excellent functional group tolerance.

Full text of DOI:10.1002/aoc.4284

Received: 1 October 2017
DOI: 10.1002/aoc.4284
Revised: 26 December 2017
Accepted: 26 December 2017
F U L L P A P E R
Highly efficient AgNO3‐catalyzed approach to
2‐(benzo[d]azol‐2‐yl)phenols from salicylaldehydes with
2‐aminothiophenol, 2‐aminophenol and benzene‐1,2‐diamine
Xinwei He
| Yuhao Wu | Wenjing Jin | Xiaoshun Wang | Cong Wu | Yongjia Shang
Key Laboratory of Functional Molecular
Solids, Ministry of Education, Anhui
Laboratory of Molecule‐Based Materials
(State Key Laboratory Cultivation Base),
College of Chemistry and Materials
Science, Anhui Normal University, Wuhu
241000, People's Republic of China
A new, convenient and efficient AgNO3‐catalyzed strategy for the preparation
of 2‐(benzo[d]azol‐2‐yl)phenol derivatives in good to excellent yields (63–98%)
is described. The reaction proceeds via condensation/intramolecular nucleo-
philic addition/oxidation process between substituted salicylaldehydes and
2‐aminothiophenol, 2‐aminophenol or benzene‐1,2‐diamine under mild reaction
conditions. Notably, this reaction utilizes cheap AgNO3 as a readily available and
low‐cost benign oxidant at low catalyst loadings with excellent functional group
tolerance.
Correspondence
Xinwei He, Key Laboratory of Functional
Molecular Solids, College of Chemistry
and Materials Science, Anhui Normal
University, Wuhu 241000, People's
Republic of China.
KEYWORDS
condensation, oxidation, phenols, salicylaldehydes, silver nitrate
Email: xinweihe@mail.ahnu.edu.cn
Funding information
Doctoral Scientific Research Foundation
of Anhui Normal University, Grant/
Award Number: 2016XJJ110; Natural
Science Foundation of Education
Administration of Anhui Province, Grant/
Award Number: KJ2016A267; National
Natural Science Foundation of China,
Grant/Award Number: 21372008,
21772001
1 | INTRODUCTION
2‐(benzo[d]azol‐2‐yl)phenols have been extensively
explored for various applications.[4] Therefore, the synthe-
Phenol and its derivatives are important compounds,
which not only are widely present in various bioactive
natural products, pharmaceuticals and many newly
developed functional materials[1] but also are used as
fundamental raw materials in Ullman coupling, Suzuki
coupling (aryl triflates, pivalates, carbamates, etc., instead
of aryl halides) and other organic reactions for the synthe-
sis of various functional molecules.[2] Phenols bearing
benzothiazole, benzoxazole and benzimidazole groups
are fluorescent compounds that are widely studied for
their fundamental photophysics and as optical probes
due to their dual emission via excited‐state intramolecular
proton transfer.[3] In particular, boron complexes of
sis of functionalized phenol derivatives has attracted
much attention in recent years.
Over the past decade, silver salt catalysts have signifi-
cantly emerged to promote a broad range of organic
transformations, such as cyclization,[5] cycloaddition,[6]
allylation,[7] tandem reactions,[8] decarboxylation[9] and
other reactions[10] owing to their efficiency, abundance,
affordability and simple operation. Very recently, silver
nitrate (AgNO3) has attracted much attention as a promis-
ing alternative to traditional transition metal catalysts and
has also been employed for organic reactions, such as
phosphorylation,[11] radical reactions,[12] addition,[13]
domino reactions[14] and others.[15]
Appl Organometal Chem. 2018;e4284.
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Copyright © 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4284

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HE ET AL.
As part of our program on the study of transition
ring of the salicylaldehyde were tolerated well, and all
para‐, meta‐ and ortho‐substituted salicylaldehydes were
easily converted into the desired products. It should be
noted that steric hindrance had an obvious effect on the
reaction. The substituted salicylaldehydes bearing bulky
tert‐butyl and bromo groups at the ortho and para posi-
tions (1 h) of the hydroxyl could give lower yields
(Table 2, entries 8 and 14). The structure of the product
5a was unambiguously confirmed by X‐ray crystallo-
graphic analysis (Figure 1).
metal‐catalyzed reactions for the synthesis of heterocyclic
compounds,[16] we herein report a convenient and
efficient method for the synthesis of 2‐(benzo[d]
azol‐2‐yl)phenol derivatives via a AgNO3‐catalyzed con-
densation/intramolecular nucleophilic addition/oxidation
process with salicylaldehydes and 2‐aminothiophenol,
2‐aminophenol or benzene‐1,2‐diamine (Scheme 1).
We next set out to explore the scope of
salicylaldehydes and 2‐aminophenols under the standard
conditions (Table 3). The results demonstrated that
the optimal conditions were compatible with various
salicylaldehydes having substituents, such as halogen
groups (fluoro, chloro, bromo), methyl, methoxyl, tert‐
butyl and diethylamino, on the aryl ring. Moreover,
tert‐butyl group at the 3,5‐position of salicylaldehydes par-
ticipated successfully in this reaction, and the correspond-
ing product 6 g was obtained in 68% yield (Table 3, entry
7). For 2‐aminophenols, substrates with a moderately
electron‐donating R5 group (e.g. CH3; Table 3, entries
11–15) or a moderately electron‐withdrawing R5 group
(e.g. Cl; Table 3, entries 17–21) gave the desired products
in good to excellent yields (83–90%). To our delight, prod-
uct 6p was obtained in 63% yield (Table 3, entry 16) with
2‐aminophenol bearing a bulky tert‐butyl group at the
para position of the hydroxyl (3c).
Furthermore, to expand the scope of the present
approach, we next subjected benzene‐1,2‐diamine (4a) to
the otherwise identical reaction conditions as described
above (Table 4). Pleasingly, the corresponding products
2‐(1H‐benzo[d]imidazol‐2‐yl)phenols were obtained in
65–92% yields, and the results are summarized in
Table 4. Likewise, various moderately electron‐withdrawing
or electron‐donating groups on the benzene ring of
salicylaldehydes, such as Cl, Br and CH3, are well tolerated
in the reaction to afford the desired products in high yields
(Table 4, entries 2, 6–8). Notably, as in the case of substrates
2‐aminobenzenethiol 2a and 2‐aminophenols 3, substrates
with a strongly electron‐donating group (e.g. OCH3, NEt2;
Table 4, entries 3 and 4) or a bulky tert‐butyl group
(Table 4, entry 5) were also tolerated in the reaction to give
the corresponding products in 90, 89 and 65% yields,
respectively.
2 | RESULTS AND DISCUSSION
As
a
model system, salicylaldehyde 1a and 2‐
aminobenzenethiol 2a were chosen as substrates for an
initial study, as summarized in Table 1. First, several tran-
sition metal catalysts, namely FeCl3, Sc(OTf)3, Cu(OAc)2,
NiCl2⋅6H2O, Hg(OAc)2, Zn(OTf)2 and AgNO3, were inves-
tigated (Table 1, entries 1–7). Of these, AgNO3 was found
to be the best catalyst, giving the desired product 5a in
78% yield (Table 1, entry 7). Other silver salts, namely
AgOAc, AgSbF6, AgOTf and AgBF4, were also screened,
identifying all of these silver salts as being effective for
this transformation (Table 1, entries 8–11). Then, screen-
ing the reaction solvent revealed that dimethylsulfoxide
(DMSO) was the solvent of choice and that the yield of
5a could be improved to 87% (Table 1, entry 15). Various
reaction temperatures and reaction times were attempted
(Table 1, entries 21–26). It was found that the highest
yield (91%) of the desired product 5a was obtained at
room temperature in a time of 1 h (Table 1, entry 25).
Additionally, altering the amount of AgNO3 gave no
significant difference in reaction yield (Table 1, entries
27–30). However, the product yield dropped to 62% in
the absence of the catalyst after a prolonged reaction time
of 5 h (Table 1, entry 31). Therefore, this reaction could be
best performed with 1 mol% of AgNO3 as catalyst in
DMSO at room temperature for 1 h (Table 1, entry 30).
With the optimum reaction conditions in hand, we
first investigated the scope of substrates for the synthesis
of 2‐(benzo[d]thiazol‐2‐yl)phenol derivatives (5). As
evident from Table 2, the tested substrates afforded good
to excellent yields (72–97%). Functional groups such
as halogen (fluoro, chloro, bromo), methyl, methoxyl,
hydroxyl, nitro, tert‐butyl and diethylamino on the phenyl
Additionally, we carried out a gram‐scale reaction
of 2‐aminobenzenethiol (2a; 10 mmol) with 2‐hydroxy‐5‐
methylbenzaldehyde (1b; 10 mmol) or 2‐hydroxy‐5‐
nitrobenzaldehyde (1 l; 10 mmol) under the standard
conditions, and the products 5b and 5 l were isolated in
94% (2.26 g) and 86% (2.34 g) yield, respectively
(Scheme 2), which showed promise for this synthetic
method as a useful tool in practical synthetic contexts.
SCHEME 1 AgNO3‐catalyzed condensation/oxidation for the
synthesis of 2‐(benzo[d]azol‐2‐yl)phenol derivatives

HE ET AL.
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TABLE 1 Optimization of reaction conditionsa
Entry
Catalyst
Solvent
Temp. (°C)
Time (h)
Yield (%)b
1
FeCl3
EtOH
70
7
54
2
Sc(OTf)3
Cu(OAc)2
NiCl2·6H2O
Hg(OAc)2
Zn(OTf)2
AgNO3
AgOAc
AgSbF6
AgOTf
EtOH
70
70
70
70
70
70
70
70
70
70
70
70
70
70
70
70
70
70
70
50
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
5
2
1
0.5
1
1
1
1
5
42
33
50
57
48
78
76
72
74
75
71
15
Trace
87
20
70
62
58
35
87
89
91
91
91
79
91
91
92
90
62
3
EtOH
4
EtOH
5
EtOH
6
EtOH
7
EtOH
8
EtOH
9
EtOH
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27c
28d
29e
30f
31
EtOH
AgBF4
EtOH
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
AgNO3
—
DMF
THF
Toluene
DMSO
CH3CN
H2O
1,4‐Dioxane
Acetone
Cyclohexane
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
aReaction conditions: salicylaldehyde 1a (1 mmol), 2‐aminobenzenethiol 2a (1 mmol), solvent (3 ml), catalyst (10 mol%).
bIsolated yield.
c15 mol% of catalyst was used.
d10 mol% of catalyst was used.
e3 mol% of catalyst was used.
f1 mol% of catalyst was used.
To gain insight into the possible mechanism of
this reaction, a few control experiments were carried
out (Scheme 3). When salicylaldehyde 1a reacted with
2‐aminobenzenethiol 2a under optimized reaction
conditions, in the absence of catalyst, the corresponding
product 5a was obtained in 56% yield. We next treated this

4 of 11
HE ET AL.
TABLE 2 AgNO3‐catalyzed synthesis of 2‐(benzo[d]thiazol‐2‐yl)phenolsa
Entry
R1, R2, R3, R4
Product 5
Yield (%)b
1
1a (H, H, H, H)
5a
90
2
1b (H, CH3, H, H)
1c (H, H, CH3, H)
1d (H, H, CH3O, H)
1e (H, H, NEt2, H)
1f (H, H, H, CH3)
5b
5c
98
92
93
93
88
89
75
91
95
97
92
88
72
87
85
90
3
4
5d
5e
5
6
5f
7
1 g (H, H, H, OCH3)
1 h (C(CH3)3, H, C(CH3)3, H)
1i (H, F, H, H)
5 g
5 h
5i
8
9
10
11
12
13
14
15
16
17
1j (H, Cl, H, H)
5j
1 k (H, Br, H, H)
5 k
5 l
5 m
5n
5o
5p
5q
1 l (H, NO2, H, H)
1 m (H, Cl, H, Cl)
1n (H, Br, H, Br)
1o (H, OH, H, H)
1p (H, H, OH, H)
1q (─CH═CHCH═CH─, H, H, H)
aReaction conditions: salicylaldehydes 1 (1 mmol), 2‐aminobenzenethiol 2a (1 mmol), DMSO (3 ml), AgNO3 (1 mol%) at room temperature.
bIsolated yield.
presence of AgNO3 as oxidant. The Ag(I) species is regen-
erated by oxidation of Ag(0) via the second oxidative pro-
cess with the assistance of DMSO/air.
3 | CONCLUSIONS
FIGURE 1 X‐ray crystal structure of compound 5a
We have described
a successful strategy for the
efficient and convenient preparation of functionalized
2‐(benzo[d]azol‐2‐yl)phenol derivatives in good to excel-
lent yields under mild conditions. The reaction proceeds
via condensation/intramolecular nucleophilic addition/
oxidation process between substituted salicylaldehydes
and 2‐aminothiophenol, 2‐aminophenol or benzene‐1,
2‐diamine in the presence of AgNO3, which could be
employed as low‐cost and moderate inorganic oxidant in
this reaction. The current strategy offers several advan-
tages such as excellent yields of products, simple starting
materials, low catalyst loadings, excellent functional
group tolerance and mild reaction conditions, hence
opening new avenues for its application in medicinal
and dye chemistry.
reaction with AgNO3 (1 equiv.) as catalyst under nitrogen
atmosphere, and the desired product 5a was obtained in
88% yield. These results indicated that the oxidation
process possibly proceeded with AgNO3 as oxidant.
On the basis of the results discussed above and
previous reports,[17] a tentative mechanism to account
for this transformation is illustrated in Scheme 4. Firstly,
intermediate A is generated from the condensation of
salicylaldehydes with 2‐substituted anilines (2a, 3a or
4a), which rapidly reaches equilibrium with another
cyclic intermediate dihydrobenzoazole B via intramolecu-
lar nucleophilic addition. Finally, the oxidation of inter-
mediate B affords the desired products and Ag(0) in the

HE ET AL.
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TABLE 3 AgNO3‐catalyzed synthesis of 2‐(benzo[d]oxazol‐2‐yl)phenolsa
Entry
R1, R2, R3, R4
R5
Product 6
Yield (%)b
1
1a (H, H, H, H)
H (3a)
6a
91
2
1b (H, CH3, H, H)
1c (H, H, CH3, H)
1d (H, H, CH3O, H)
1e (H, H, NEt2, H)
1 g (H, H, H, CH3O)
1 h (C(CH3)3, H, C(CH3)3, H)
1j (H, Cl, H, H)
H (3a)
6b
6c
92
89
87
82
73
68
92
91
89
83
90
89
88
85
63
89
88
89
89
87
3
H (3a)
4
H (3a)
6d
6e
5
H (3a)
6
H (3a)
6f
7
H (3a)
6 g
6 h
6i
8
H (3a)
9
1 k (H, Br, H, H)
1q (─CH═CHCH═CH─, H, H, H)
1a (H, H, H, H)
H (3a)
10
11
12
13
14
15
16
17
18
19
20
21
H (3a)
6j
CH3 (3b)
CH3 (3b)
CH3 (3b)
CH3 (3b)
CH3 (3b)
tBu (3c)
Cl (3d)
Cl (3d)
Cl (3d)
Cl (3d)
Cl (3d)
6 k
6 l
6 m
6n
6o
6p
6q
6r
1b (H, CH3, H, H)
1i (H, F, H, H)
1j (H, Cl, H, H)
1 k (H, Br, H, H)
1j (H, Cl, H, H)
1a (H, H, H, H)
1i (H, F, H, H)
1j (H, Cl, H, H)
6 s
6 t
6u
1 k (H, Br, H, H)
1 l (H, NO2, H, H)
aReaction conditions: salicylaldehydes 1 (1 mmol), 2‐aminophenols 3 (1 mmol), DMSO (3 ml), AgNO3 (1 mol%) at room temperature.
bIsolated yield.
are described as s (singlet), d (doublet), t (triplet), q
(quartet) or m (multiplet), and the coupling constants (J)
are reported in hertz. The HRMS analyses with a quadru-
pole time‐of‐flight mass spectrometer yielded ion mass/
charge (m/z) ratios in atomic mass units.
4 | EXPERIMENTAL
4.1 | General
Unless otherwise specified, all reagents and starting mate-
rials were purchased from commercial sources and used
as received, and the solvents were purified and dried
using standard procedures. The chromatography solvents
were of technical grade and distilled prior to use. Flash
chromatography was performed using 200–300 mesh
silica gel with the indicated solvent system according to
4.2 | General Procedure for Synthesis of
2‐(Benzo[d]thiazol‐2‐yl)phenols (3)
To a solution of salicylaldehydes (1; 1 mmol), 2‐
aminobenzenethiol (2a; 1 mmol) and AgNO3 (0.01 mmol)
in DMSO (3 ml) were added and the resulting mixture was
stirred at room temperature. Upon the completion of this
reaction (monitored by TLC), the mixture was diluted with
CH2Cl2 (3 × 10 ml), and washed with brine. Organic layers
were combined, dried over Na2SO4, filtered and evapo-
rated in a vacuum. The residue was further purified by
1
standard techniques. The H NMR and 13C NMR spectra
were recorded using 300 MHz spectrometers unless other-
wise specified. The chemical shifts (δ) in parts per million
are reported relative to the residual signals of chloroform
(7.26 ppm for 1H and 77.16 ppm for 13C), and all 13C NMR
spectra that were recorded with broadband proton
decoupling are denoted 13C{1H}NMR. The multiplicities

6 of 11
HE ET AL.
TABLE 4 AgNO3‐catalyzed synthesis of 2‐(1H‐benzo[d]imidazol‐2‐yl)phenolsa
Entry
R1, R2, R3, R4
Product 7
Yield (%)b
1
1a (H, H, H, H)
7a
90
2
3
4
5
6
7
8
9
1b (H, CH3, H, H)
7b
7c
7d
7e
7f
82
90
89
65
88
87
88
92
1d (H, H, CH3O, H)
1e (H, H, NEt2, H)
1 h (C(CH3)3, H, C(CH3)3, H)
1i (H, F, H, H)
1j (H, Cl, H, H)
7 g
7 h
7i
1 k (H, Br, H, H)
1q (─CH═CHCH═CH─, H, H, H)
aReaction conditions: salicylaldehydes 1 (1 mmol), benzene‐1,2‐diamine 4a (1 mmol), DMSO (3 ml), AgNO3 (1 mol%) at room temperature.
bIsolated yield.
flash column chromatography on silica gel (200–300
mesh) with petroleum ether and ethyl acetate (6:1–8:1,
v/v) as eluting solvent to give the desired products (5).
2‐(Benzo[d]thiazol‐2‐yl)phenol (5a). 1H NMR
(300 MHz, CDCl3, δ, ppm): 12.55 (s, 1H), 8.00 (d, J = 8.1 Hz,
1H), 7.91 (d, J = 7.8 Hz, 1H), 7.70 (d, J = 7.5 Hz, 1H),
7.51 (t, J = 7.5 Hz, 1H), 7.36–7.43 (m, 2H), 7.13
(d, J = 8.1 Hz, 1H), 6.96 (t, J = 7.5 Hz, 1H). 13C NMR
(125 MHz, CDCl3, δ, ppm): 169.7, 158.3, 152.2, 133.1,
133.0, 128.8, 127.1, 125.9, 122.5, 121.9, 119.9, 118.2,
117.1. HRMS (APCI) calcd for [C13H9NOS + H]+
228.0483, found 228.0483.
SCHEME 2 Gram‐scale synthesis
2‐(Benzo[d]thiazol‐2‐yl)‐4‐methylphenol (5b). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.32 (s, 1H), 8.00
(d, J = 8.1 Hz, 1H), 7.92 (d, J = 7.5 Hz, 1H), 7.51
(t, J = 7.5 Hz, 2H), 7.43 (t, J = 7.2 Hz, 1H), 7.21
(d, J = 7.2 Hz, 1H), 7.03 (d, J = 8.4 Hz, 1H), 2.36 (s, 3H,
CH3). 13C NMR (125 MHz, CDCl3, δ, ppm): 169.8, 156.2,
152.3, 134.1, 133.0, 129.0, 128.7, 127.0, 125.8, 122.5,
121.8, 118.0, 116.7, 20.8. HRMS (APCI) calcd for
[C14H11NOS + H]+ 242.0639, found 242.0640.
SCHEME 3 Control experiments
2‐(Benzo[d]thiazol‐2‐yl)‐5‐methylphenol (5c). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.03 (s, 1H, OH), 8.62
(s, 1H, C6H4), 7.67 (d, J = 7.2 Hz, 1H, C6H4), 7.14–7.29
(m, 4H, C6H4), 6.87 (t, J = 7.5 Hz, 1H, C6H4),
2.34(s, 3H). 13C NMR (125 MHz, CDCl3, δ, ppm): 163.4,
159.8, 146.8, 135.0, 132.0, 130.7, 127.9, 127.4, 126.9,
119.1, 118.8, 118.0, 16.0. HRMS (APCI) calcd for
[C14H11NOS + H]+ 242.0639, found 242.0640.
2‐(Benzo[d]thiazol‐2‐yl)‐5‐methoxyphenol (5d). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.77 (s, 1H), 7.94
SCHEME 4 Proposed reaction mechanism

HE ET AL.
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(d, J = 8.1 Hz, 1H), 7.87 (d, J = 7.8 Hz, 1H), 7.58
(d, J = 8.4 Hz, 1H), 7.47 (t, J = 7.2 Hz, 1H), 7.37
(t, J = 7.5 Hz, 1H), 6.60 (s, 1H), 6.55 (d, J = 8.7 Hz, 1H),
3.86 (s, 3H). 13C NMR (125 MHz, CDCl3, δ, ppm): 169.6,
163.8, 160.3, 152.2, 132.5, 130.0, 126.9, 125.3, 122.0,
121.7, 110.7, 108.0, 101.7, 55.8. HRMS (APCI) calcd for
[C14H11NO2S + H]+ 258.0589, found 258.0589.
2‐(Benzo[d]thiazol‐2‐yl)‐5‐(diethylamino)phenol (5e).
1H NMR (300 MHz, CDCl3, δ, ppm): 12.58 (s, 1H), 7.87
(d, J = 8.1 Hz, 1H), 7.82 (d, J = 7.2 Hz, 1H), 7.40–7.48
(m, 2H), 7.30 (t, J = 7.5 Hz, 1H), 6.29 (d, J = 6.0 Hz,
2H), 3.42 (q, J = 6.9 Hz, 4H), 1.22 (t, J = 6.9 Hz, 6H).
13C NMR (125 MHz, CDCl3, δ, ppm): 170.0, 160.2, 152.6,
151.7, 132.3, 130.2, 126.6, 124.5, 121.6, 121.4, 106.2,
104.5, 104.5, 98.2, 44.9, 13.1. HRMS (APCI) calcd for
[C17H18N2OS + H]+ 299.1218, found 299.1219.
2‐(Benzo[d]thiazol‐2‐yl)‐4‐chlorophenol (5j). 1H NMR
(500 MHz, CDCl3, δ, ppm): 12.53 (s, 1H), 8.00 (d, J =
7.5 Hz, 1H), 7.92 (d, J = 8.5 Hz, 1H), 7.64 (s, 1H), 7.52
(t, J = 7.5 Hz, 1H), 7.43 (t, J = 7.5 Hz, 1H), 7.32 (d, J =
7.5 Hz, 1H), 7.05 (d, J = 9.0 Hz, 1H). 13C NMR
(125 MHz, CDCl3, δ, ppm): 168.2, 156.9, 152.0, 133.0,
132.9, 127.9, 127.3, 126.3, 124.5, 122.7, 122.0, 119.8,
118.0. HRMS (APCI) calcd for [C13H8ClNOS + H]+
262.0093, found 262.0093.
2‐(Benzo[d]thiazol‐2‐yl)‐4‐bromophenol (5 k). 1H
NMR (500 MHz, CDCl3, δ, ppm): 12.57 (s, 1H), 8.01
(d, J = 8.5 Hz, 1H), 7.93 (d, J = 8.0 Hz, 1H), 7.79 (d, J =
6.5 Hz, 1H), 7.53 (t, J = 7.5 Hz, 1H), 7.43–7.46 (m, 2H),
7.01 (d, J = 8.5 Hz, 1H). 13C NMR (125 MHz, CDCl3, δ,
ppm): 168.1, 157.4, 152.0, 135.7, 133.0, 130.8, 127.3,
126.3, 122.7, 122.0, 120.2, 118.7, 111.4. HRMS (APCI)
calcd for [C13H8BrNOS + H]+ 305.9588, found 305.9588.
2‐(Benzo[d]thiazol‐2‐yl)‐6‐methylphenol (5f). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.77 (s, 1H, OH), 7.98
(d, J = 7.8 Hz, 1H), 7.91 (d, J = 7.5 Hz, 1H), 7.47–7.57
(m, 2H), 7.39 (t, J = 7.5 Hz, 1H), 6.86 (t, J = 7.8 Hz,
1H), 2.35 (s, 3H). 13C NMR (125 MHz, CDCl3, δ, ppm):
170.2, 156.6, 152.2, 134.0, 133.1, 127.3, 127.0, 126.4,
125.8, 122.4, 121.8, 119.3, 116.4, 16.4. HRMS (APCI) calcd
for [C14H11NOS + H]+ 242.0639, found 242.0640.
1
2‐(Benzo[d]thiazol‐2‐yl)‐4‐nitrophenol (5 l). H NMR
(300 MHz, CDCl3, δ, ppm): 13.53 (s, 1H), 8.64 (s, 1H),
8.28 (d, J = 9.3 Hz, 1H), 8.05 (d, J = 7.8 Hz, 1H), 7.99
(d, J = 8.1 Hz, 1H), 7.48–7.60 (m, 2H), 7.21 (d, J =
9.0 Hz, 1H). 13C NMR (125 MHz, CDCl3, δ, ppm): 167.6,
163.5, 151.5, 140.6, 133.0, 128.1, 127.6, 126.9, 124.9,
122.9, 119.0, 116.8. HRMS (APCI) calcd for [C13H8N2O3S
+ H]+ 273.0334, found 273.0334.
2‐(Benzo[d]thiazol‐2‐yl)‐6‐methoxyphenol (5 g). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.74 (s, 1H), 7.98
(d, J = 8.1 Hz, 1H), 7.87 (d, J = 7.8 Hz, 1H), 7.47
(t, J = 7.5 Hz, 1H), 7.37 (t, J = 7.5 Hz, 1H), 7.29
(d, J = 7.5 Hz, 1H), 6.97 (d, J = 7.5 Hz, 1H), 6.87
(d, J = 8.1 Hz, 1H), 3.94 (s, 3H). 13C NMR (75 MHz,
CDCl3, δ, ppm): 169.3, 151.7, 148.9, 148.2, 132.6, 126.6,
125.5, 122.2, 121.4, 119.9, 119.1, 116.7, 114.0, 56.2.
HRMS (APCI) calcd for [C14H11NO2S + H]+ 258.0589,
found 258.0589.
1
2‐(Benzo[d]thiazol‐2‐yl)‐4,6‐dichlorophenol (5 m). H
NMR (300 MHz, CDCl3, δ, ppm): 13.30 (s, 1H), 7.98 (d, J
= 8.1 Hz, 1H), 7.92 (d, J = 7.5 Hz, 1H), 7.42–7.53
(m, 4H). 13C NMR (75 MHz, CDCl3, δ, ppm): 167.2,
152.7, 151.2, 132.7, 132.2, 127.2, 126.3, 125.9, 123.8,
123.6, 122.5, 121.7, 118.2. HRMS (APCI) calcd for
[C13H7Cl2NOS + H]+ 295.9704, found 295.9704.
2‐(Benzo[d]thiazol‐2‐yl)‐4,6‐dibromophenol (5n). 1H
NMR (300 MHz, CDCl3, δ, ppm): 13.53 (s, 1H), 8.02
(d, J = 8.1 Hz, 1H), 7.97 (d, J = 7.5 Hz, 1H), 7.78 (s, 1H),
7.49–7.59 (m, 3H). 13C NMR (125 MHz, CDCl3, δ, ppm):
167.3, 154.4, 151.5, 138.1, 133.1, 130.0, 127.6, 126.7,
122.9, 122.1, 119.1, 113.2, 111.2. HRMS (APCI) calcd for
[C13H7Br2NOS + H]+ 385.8673, found 385.8673.
2‐(Benzo[d]thiazol‐2‐yl)‐4,6‐di‐tert‐butylphenol (5 h).
1H NMR (300 MHz, CDCl3, δ, ppm): 13.22 (s, 1H), 8.67
(s, 1H), 7.69 (d, J = 7.5 Hz, 1H), 7.51 (s, 1H), 7.16–7.26
(m, 3H), 1.51 (s, 9H), 1.36 (s, 9H). 13C NMR (125 MHz,
CDCl3, δ, ppm): 164.4, 158.8, 147.0, 141.1, 137.6, 132.0,
129.0, 127.8, 127.5, 127.2, 118.7, 118.1, 35.5, 34.6, 31.8,
29.8. HRMS (APCI) calcd for [C21H25NOS + H]+
340.1735, found 340.1733.
2‐(Benzo[d]thiazol‐2‐yl)benzene‐1,4‐diol (5o). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.09 (s, 1H), 8.00
(d, J = 7.8 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.50 (t, J =
7.5 Hz, 1H), 7.41 (t, J = 7.2 Hz, 1H), 7.17 (s, 1H), 7.01
(d, J = 8.7 Hz, 1H), 6.92 (d, J = 9.0 Hz, 1H), 4.72 (s, 1H).
13C NMR (125 MHz, CDCl3, δ, ppm): 164.0, 152.3, 148.0,
126.7, 125.6, 122.2, 121.5, 120.8, 118.7, 113.7. HRMS
(APCI) calcd for [C13H9NO2S + H]+ 244.0432, found
244.0433.
1
2‐(Benzo[d]thiazol‐2‐yl)‐4‐fluorophenol (5i). H NMR
(300 MHz, CDCl3, δ, ppm): 12.31 (s, 1H), 8.00
(d, J = 8.1 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.51
(t, J = 7.5 Hz, 1H), 7.42 (d, J = 7.5 Hz, 1H), 7.36
(t, J = 8.7 Hz, 1H), 7.02–7.13 (m, 2H). 13C NMR
(75 MHz, CDCl3, δ, ppm): 167.1, 156.1, 153.1(1JCF
=
9.3 Hz), 150.6, 131.6, 125.8 (1JCF = 75.8 Hz), 121.3,
120.5, 118.9 (1JCF = 23.1 Hz), 118.0 (1JCF = 7.7 Hz),
115.5 (1JCF = 7.7 Hz), 112.7 (1JCF = 24.5 Hz). HRMS
(APCI) calcd for [C13H8FNOS + H]+ 246.0389, found
246.0391.
4‐(Benzo[d]thiazol‐2‐yl)benzene‐1,3‐diol (5p). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.10 (s, 1H), 8.00
(d, J = 8.1 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.51 (t, J =
7.5 Hz, 1H), 7.41 (d, J = 7.2 Hz, 1H), 7.17 (s, 1H), 7.01
(d, J = 9.0 Hz, 1H), 6.92 (d, J = 7.2 Hz, 1H), 4.73 (s, 1H).

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HE ET AL.
13C NMR (125 MHz, CDCl3, δ, ppm): 169.2, 152.6, 148.5,
133.1, 127.1, 126.0, 122.6, 121.9, 121.2, 119.1, 117.0,
114.1. HRMS (APCI) calcd for [C13H9NO2S + H]+
244.0432, found 244.0433.
2‐(Benzo[d]oxazol‐2‐yl)‐6‐methoxyphenol (6f). 1H
NMR (300 MHz, DMSO‐d6, δ, ppm): 12.51 (s, 1H), 8.69
(s, 1H), 7.15–7.21 (m, 2H), 6.88–7.07 (m, 5H), 3.92 (s,
3H). 13C NMR (75 MHz, CDCl3, δ, ppm): 163.2, 150.8,
150.2, 148.4, 135.4, 128.8, 123.9, 120.9, 119.3, 119.1,
118.1, 116.0, 115.2, 56.2. HRMS (APCI) calcd for
[C14H11NO3 + H]+ 242.0817, found 242.0815.
2‐(Benzo[d]oxazol‐2‐yl)‐4,6‐di‐tert‐butylphenol (6 g).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 8.70 (s, 1H),
7.49 (s, 1H), 7.14–7.20 (m, 2H), 6.93–7.04 (m, 2H), 5.89
(s, 1H), 1.47 (s, 9H), 1.33 (s, 9H). 13C NMR (75 MHz,
CDCl3, δ, ppm): 165.2, 157.7, 149.8, 141.2, 137.1, 135.9,
128.7, 128.4, 127.2, 120.9, 118.4, 118.2, 115.6, 35.1, 34.2,
31.4, 29.4. HRMS (APCI) calcd for [C21H25NO2 + H]+
324.1964, found 324.1964.
1‐(Benzo[d]thiazol‐2‐yl)naphthalen‐2‐ol (5q). 1H
NMR (300 MHz, CDCl3, δ, ppm): 14.24 (s, 1H), 8.82
(d, J = 8.7 Hz, 1H), 8.08 (d, J = 8.1 Hz, 1H), 7.98 (d, J =
7.2 Hz, 1H), 7.84–7.88 (m, 2H), 7.65 (t, J = 7.2 Hz, 1H),
7.56 (t, J = 7.2 Hz, 1H), 7.41‐7.47 (m, 2H), 7.35 (d, J =
9.0 Hz, 1H). 13C NMR (125 MHz, CDCl3, δ, ppm): 167.0,
159.4, 149.9, 134.2, 133.2, 131.5, 129.9, 128.9, 128.5,
127.1, 125.7, 124.0, 122.9, 122.0, 121.5, 121.4, 120.2,
109.9. HRMS (APCI) calcd for [C17H11NOS + H]+
278.0640, found 278.0640.
2‐(Benzo[d]oxazol‐2‐yl)phenol
(6a).
1H
NMR
(300 MHz, CDCl3, δ, ppm): 12.28 (s, 1H), 8.67 (s, 1H),
7.41 (t, J = 7.5 Hz, 2H), 7.21 (d, J = 7.8 Hz, 1H), 7.15 (d,
J = 7.5 Hz, 1H), 6.94–7.05 (m, 4H). 13C NMR (125 MHz,
CDCl3, δ, ppm): 164.3, 160.9, 150.2, 136.2, 134.1, 133.1,
129.1, 121.4, 119.9, 118.7, 117.6, 116.2. HRMS (APCI)
calcd for [C13H9NO2 + H]+ 212.0712, found 212.0712.
2‐(Benzo[d]oxazol‐2‐yl)‐4‐methylphenol (6b). 1H
NMR (300 MHz, DMSO‐d6, δ, ppm): 12.07 (s, 1H), 8.62
(s, 1H), 7.18–7.23 (m, 2H), 7.13 (d, J = 7.8 Hz, 1H),
6.92–7.03 (m, 3H), 2.32 (s, 3H). 13C NMR (75 MHz, CDCl3,
δ, ppm): 164.0, 158.3, 149.9, 136.0, 134.7, 132.7, 128.7,
121.0, 118.9, 118.3, 117.0, 115.8, 20.3. HRMS (APCI) calcd
for [C14H11NO2 + H]+ 226.0868, found 226.0867.
2‐(Benzo[d]oxazol‐2‐yl)‐4‐chlorophenol (6 h). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.34 (s, 1H), 8.61
(s, 1H), 7.32–7.39 (m, 1H), 7.23 (d, J = 8.1 Hz, 1H), 7.15
(d, J = 7.8 Hz, 1H), 6.97–7.03 (m, 3H). 13C NMR
(125 MHz, CDCl3, δ, ppm): 162.7, 159.5, 150.3, 135.6,
133.8, 131.9, 129.6, 124.6, 121.6, 120.4, 119.2, 118.7,
117.6, 116.5. HRMS (APCI) calcd for [C13H8ClNO2 + H]
+
246.0322, found 246.0324.
2‐(Benzo[d]oxazol‐2‐yl)‐4‐bromophenol (6i). H NMR
1
(300 MHz, CDCl3, δ, ppm): 12.37 (s, 1H), 8.60 (s, 1H),
7.54 (s, 1H), 7.49 (d, J = 8.7 Hz, 1H), 7.20–7.23 (m, 1H),
7.14 (d, J = 7.8 Hz, 1H), 6.99–7.03 (m, 1H), 6.97 (d, J =
6.3 Hz, 1H). 13C NMR (125 MHz, CDCl3, δ, ppm): 162.6,
159.9, 150.3, 136.6, 135.6, 135.0, 129.6, 121.6, 121.0,
119.6, 118.8, 116.5, 111.4. HRMS (APCI) calcd for
[C13H8BrNO2 + H]+ 289.9817, found 289.9817.
2‐(Benzo[d]oxazol‐2‐yl)‐5‐methylphenol (6c). 1H
NMR (300 MHz, DMSO‐d6, δ, ppm): 12.17 (s, 1H), 8.63
(s, 1H), 7.31 (d, J = 7.8 Hz, 1H), 7.19 (t, J = 7.5 Hz, 1H),
7.13 (d, J = 7.8 Hz, 1H), 6.92–7.02 (m, 1H), 6.85 (s, 1H),
6.80 (d, J = 8.1 Hz, 1H), 2.38 (s, 3H). 13C NMR (75 MHz,
CDCl3, δ, ppm): 164.0, 158.3, 149.9, 136.0, 134.7, 132.7,
128.7, 121.0, 118.9, 118.3, 117.0, 115.8, 20.3. HRMS (APCI)
calcd for [C14H11NO2 + H]+ 226.0868, found 226.0867.
2‐(Benzo[d]oxazol‐2‐yl)‐5‐methoxyphenol (6d). 1H
NMR (300 MHz, DMSO‐d6, δ, ppm): 12.66 (s, 1H), 8.56
(s, 1H), 7.31 (d, J = 8.7 Hz, 1H), 7.17 (t, J = 7.2 Hz, 1H),
7.02 (d, J = 8.4 Hz, 1H), 6.94 (t, J = 7.2 Hz, 1H), 6.51–
6.54 (m, 2H), 3.84 (s, 3H). 13C NMR (75 MHz, CDCl3, δ,
ppm): 163.0, 149.6, 134.0, 128.1, 121.5, 120.9, 119.5,
118.2, 115.6, 115.1, 107.6, 101.0, 55.5. HRMS (APCI) calcd
for [C14H11NO3 + H]+ 242.0817, found 242.0817.
2‐(Benzo[d]oxazol‐2‐yl)‐5‐(diethylamino)phenol (6e).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 8.41 (s, 1H),
7.19 (d, J = 8.4 Hz, 1H), 7.09 (t, J = 6.9 Hz, 2H), 7.00
(d, J = 8.1 Hz, 1H), 6.91 (t, J = 7.2 Hz, 1H), 6.28 (d, J =
8.7 Hz, 1H), 6.18 (s, 1H), 3.41 (q, J = 6.9 Hz, 4H), 1.20
(t, J = 6.9 Hz, 6H). 13C NMR (75 MHz, CDCl3, δ, ppm):
161.7, 152.2, 149.6, 134.4, 127.0, 120.7, 117.8, 115.3,
104.1, 97.5, 44.6, 12.6. HRMS (APCI) calcd for
[C17H18N2O2 + H]+ 283.1447, found 283.1447.
1
1‐(Benzo[d]oxazol‐2‐yl)naphthalen‐2‐ol (6j). H NMR
(500 MHz, DMSO‐d6, δ, ppm): 10.31 (s, 1H), 9.48 (d, J =
10.0 Hz, 1H), 8.36 (d, J = 8.5 Hz, 1H), 7.91 (d, J =
8.0 Hz, 1H), 7.77 (d, J = 9.5 Hz, 1H), 7.64 (d, J = 7.5 Hz,
1H), 7.44 (t, J = 7.5 Hz, 1H), 7.22 (t, J = 8.0 Hz, 1H),
7.05 (t, J = 7.5 Hz, 1H), 6.98 (d, J = 8.0 Hz, 1H), 6.91
(t, J = 8.0 Hz, 1H), 6.76 (d, J = 9.5 Hz, 1H). 13C NMR
(125 MHz, DMSO‐d6, δ, ppm): 178.5, 150.1, 149.2, 138.7,
134.7, 129.8, 129.3, 128.9, 127.5, 126.6, 125.9, 123.8,
120.6,120.5, 118.4, 116.7, 108.5. HRMS (APCI) calcd for
[C17H11NO2 + H]+ 262.0868, found 262.0868.
2‐(5‐Methylbenzo[d]oxazol‐2‐yl)phenol (6 k). 1H
NMR (300 MHz, CDCl3, δ, ppm): 12.29 (s, 1H), 8.66
(s, 1H), 7.40 (d, J = 7.8 Hz, 1H), 6.94–7.07 (m, 3H), 6.84
(s, 1H), 6.78 (d, J = 7.8 Hz, 1H), 2.34 (s, 3H). 13C NMR
(75 MHz, CDCl3, δ, ppm): 163.2, 160.8, 150.1, 139.7,
133.9, 133.5, 132.9, 122.1, 119.9, 119.7, 118.1, 117.5,
116.8, 21.6. HRMS (APCI) calcd for [C14H11NO2 + H]+
226.0868, found 226.0868.
4‐Methyl‐2‐(5‐methylbenzo[d]oxazol‐2‐yl)phenol (6 l).
1H NMR (300 MHz, CDCl3, δ, ppm): 12.14 (s, 1H), 8.60
(s, 1H), 7.21 (d, J = 6.9 Hz, 1H), 7.04 (d, J = 8.4 Hz, 1H),

HE ET AL.
9 of 11
6.94 (d, J = 8.7 Hz, 1H), 6.84 (s, 1H), 6.78 (d, J = 7.8 Hz,
1H), 2.34 (s, 3H). 13C NMR (75 MHz, CDCl3, δ, ppm):
162.8, 158.2, 149.7, 139.1, 134.3, 133.3, 132.5, 128.6,
121.7, 119.0, 117.7, 116.9, 116.4, 21.2, 20.3. HRMS (APCI)
calcd for [C15H13NO2 + H]+ 240.1025, found 240.1025.
4‐Fluoro‐2‐(5‐methylbenzo[d]oxazol‐2‐yl)phenol (6 m).
1H NMR (300 MHz, CDCl3, δ, ppm): 12.41 (s, 1H), 8.60
(s, 1H), 7.54 (s, 1H), 7.48 (d, J = 7.8 Hz, 1H), 7.06
(d, J = 8.1 Hz, 1H), 6.95 (d, J = 8.7 Hz, 1H), 6.85 (s, 1H),
6.79 (d, J = 8.1 Hz, 1H), 2.34 (s, 3H). 13C NMR (75 MHz,
CDCl3, δ, ppm): 161.0, 159.5, 149.7, 139.8, 135.9, 134.4,
132.6, 121.9, 120.8, 119.2, 117.8, 116.6, 111.0, 21.3. HRMS
(APCI) calcd for [C14H10FNO2 + H]+ 244.0774, found
244.0774.
4‐Chloro‐2‐(5‐methylbenzo[d]oxazol‐2‐yl)phenol (6n).
1H NMR (300 MHz, CDCl3, δ, ppm): 12.36 (s, 1H), 8.60
(s, 1H), 7.39 (s, 1H), 7.34 (d, J = 8.7 Hz, 1H), 7.06
(d, J = 8.1 Hz, 1H), 6.99 (d, J = 8.7 Hz, 1H), 6.84
(s, 1H), 6.79 (d, J = 8.1 Hz, 1H), 2.34 (s, 3H). 13C NMR
(75 MHz, CDCl3, δ, ppm): 161.5, 159.4, 150.1, 140.2,
133.5, 133.0, 131.8, 124.6, 122.3, 119.1, 118.2, 117.0,
21.6. HRMS (APCI) calcd for [C14H10ClNO2 + H]+
260.0478, found 260.0475.
(m, 1H). 13C NMR (75 MHz, DMSO‐d6, δ, ppm): 161.2,
157.1, 153.8, 152.6, 134.6, 132.2, 121.3, 120.5 (1JCF
91.8 Hz), 119.9, 118.5 (1JCF = 29.7 Hz), 117.4 (1JCF
=
=
92.4 Hz), 116.6. HRMS (APCI) calcd for [C13H7ClFNO2
+ H]+ 264.0228, found 264.0228.
4‐Chloro‐2‐(5‐chlorobenzo[d]oxazol‐2‐yl)phenol (6 s).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 13.46 (s, 1H),
10.29 (s, 1H), 8.93 (s, 1H), 7.71 (s, 1H), 7.34–7.41 (m,
1H), 6.91‐6.98 (m, 2H). 13C NMR (75 MHz, DMSO‐d6, δ,
ppm): 161.0, 159.7, 152.6, 133.0, 131.3, 121.2, 121.1,
119.9, 119.1, 116.6. HRMS (APCI) calcd for [C13H7Cl2NO2
+ H]+ 279.9932, found 279.9931.
4‐Bromo‐2‐(5‐chlorobenzo[d]oxazol‐2‐yl)phenol (6 t).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 13.47 (s, 1H),
10.27 (s, 1H), 8.93 (s, 1H), 7.84 (s, 1H), 7.33–7.52
(m, 1H), 6.88–6.96 (m, 2H). 13C NMR (75 MHz, DMSO‐
d6, δ, ppm): 160.9, 160.1, 152.6, 135.7, 134.4, 132.3, 121.8,
121.2, 119.9, 119.6, 116.6, 110.0. HRMS (APCI) calcd for
[C13H7BrClNO2 + H]+ 323.9427, found 323.9427.
2‐(5‐Chlorobenzo[d]oxazol‐2‐yl)‐4‐nitrophenol (6u).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 15.26 (s, 1H),
10.70 (s, 1H), 9.23 (s, 1H), 8.61 (s, 1H), 8.21 (d, J = 9.0 Hz,
1H), 7.54 (d, J = 9.0 Hz, 1H), 6.99 (d, J = 9.0 Hz, 1H). 13C
NMR (75 MHz, DMSO‐d6, δ, ppm): 170.3, 160.4, 152.2,
138.3, 133.0, 131.2, 129.9, 129.0, 120.9, 120.1, 119.9,
117.9, 116.7. HRMS (APCI) calcd for [C13H7ClN2O4 + H]+
291.0173, found 291.0173.
4‐Bromo‐2‐(5‐methylbenzo[d]oxazol‐2‐yl)phenol (6o).
1H NMR (300 MHz, CDCl3, δ, ppm): 12.45 (s, 1H), 8.60
(s, 1H), 7.53 (s, 1H), 7.47 (d, J = 7.8 Hz, 1H), 7.06 (d, J =
8.1 Hz, 1H), 6.94 (d, J = 8.4 Hz, 1H), 6.84 (s, 1H), 6.79
(d, J = 7.8 Hz, 1H), 2.34 (s, 3H). 13C NMR (75 MHz,
CDCl3, δ, ppm): 160.4, 159.0, 151.7, 138.8, 135.2, 134.1,
132.1, 132.0, 129.1, 121.8, 120.8, 119.6, 119.4, 117.5, 21.3.
HRMS (APCI) calcd for [C14H10BrNO2 + H]+ 303.9973,
found 303.9975.
2‐(1H‐Benzo[d]imidazol‐2‐yl)phenol (7a). 1H NMR
(300 MHz, DMSO‐d6, δ, ppm): 13.16 (s, 1H), 8.06
(d, J = 7.8 Hz, 1H), 7.72 (d, J = 7.8 Hz, 2H), 7.27–7.39
(m, 3H), 7.01 (t, J = 9.0 Hz, 2H). 13C NMR (125 MHz,
DMSO‐d6, δ, ppm): 158.8, 152.5, 141.5, 134.0, 132.5,
127.0, 124.1, 123.3, 119.9, 118.9, 118.0, 113.4, 112.3. HRMS
(APCI) calcd for [C13H10N2O + H]+ 211.0871, found
211.0871.
2‐(1H‐Benzo[d]imidazol‐2‐yl)‐4‐methylphenol (7b).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 12.90 (s, 1H),
7.85 (s, 1H), 7.62 (s, 2H), 7.13–7.24 (m, 2H), 6.92
(t, J = 8.1 Hz, 1H). 13C NMR (75 MHz, DMSO‐d6, δ,
ppm): 156.3, 152.2, 141.4, 132.8, 128.1, 126.6, 123.5,
122.8, 118.3, 117.4, 112.6, 111.9, 20.6. HRMS (APCI) calcd
for [C14H12N2O + H]+ 225.1028, found 225.1026.
2‐(1H‐Benzo[d]imidazol‐2‐yl)‐5‐methoxyphenol (7c).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 13.36 (s, 1H),
7.95 (d, J = 8.7 Hz, 1H), 7.63 (s, 1H), 7.54 (s, 1H), 7.22
(s, 2H), 6.59 (t, J = 8.7 Hz, 2H), 3.78 (s, 3H). 13C NMR
(75 MHz, DMSO‐d6, δ, ppm): 162.6, 160.4, 152.5, 141.2,
133.4, 127.7, 123.2, 122.6, 117.9, 111.6, 107.0, 106.1,
101.9, 55.7. HRMS (APCI) calcd for [C14H12N2O2 + H]+
241.0977, found 241.0978.
2‐(5‐(tert‐Butyl)benzo[d]oxazol‐2‐yl)‐4‐chlorophenol
(6p). 1H NMR (300 MHz, DMSO‐d6, δ, ppm): 13.90
(s, 1H), 9.57 (s, 1H), 8.98 (s, 1H), 7.73 (s, 1H), 7.39
(d, J = 9.0 Hz, 1H), 7.33 (s, 1H), 7.17 (s, J = 8.4 Hz, 1H),
6.95 (d, J = 9.3 Hz, 1H), 6.88 (d, J = 8.7 Hz, 1H), 1.21
(s, 9H). 13C NMR (75 MHz, DMSO‐d6, δ, ppm): 160.3,
149.3, 142.5, 135.4, 134.4, 130.1, 125.7, 121.7, 119.6,
116.5, 31.7, 29.4. HRMS (APCI) calcd for [C17H16ClNO2
+ H]+ 302.0948, found 302.0946.
1
2‐(5‐Chlorobenzo[d]oxazol‐2‐yl)phenol (6q). H NMR
(300 MHz, DMSO‐d6, δ, ppm): 13.50 (s, 1H), 10.24
(s, 1H), 8.94 (s, 1H), 7.60 (d, J = 7.2 Hz, 1H), 7.38 (t, J =
7.8 Hz, 1H), 6.91–6.97 (m, 3H). 13C NMR (75 MHz,
DMSO‐d6, δ, ppm): 162.8, 161.0, 152.5, 134.8, 133.5,
132.8, 131.8, 121.3, 119.9, 119.3, 117.1, 116.5. HRMS
(APCI) calcd for [C13H8ClNO2 + H]+ 246.0322, found
246.0324.
2‐(5‐Chlorobenzo[d]oxazol‐2‐yl)‐4‐fluorophenol (6r).
1H NMR (300 MHz, DMSO‐d6, δ, ppm): 13.09 (s, 1H),
10.24 (s, 1H), 8.92 (s, 1H), 7.51 (d, J = 8.7 Hz, 1H), 7.36
(d, J = 8.1 Hz, 1H), 7.24 (t, J = 8.7 Hz, 1H), 6.90–6.97
2‐(1H‐Benzo[d]imidazol‐2‐yl)‐5‐(diethylamino)phenol
(7d). 1H NMR (300 MHz, DMSO‐d6, δ, ppm): 7.53 (s, 2H),
7.40 (d, J = 9.0 Hz, 1H), 7.20–7.23 (m, 2H), 6.30 (s, 1H),

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HE ET AL.
6.25 (d, J = 7.5 Hz, 1H), 3.36 (q, J = 6.9 Hz, 4H), 1.16
(t, J = 6.9 Hz, 6H). 13C NMR (125 MHz, DMSO‐d6, δ,
ppm): 160.7, 153.8, 151.1, 128.0, 122.8, 104.4, 101.1, 98.6,
44.5, 13.4. HRMS (APCI) calcd for [C17H19N3O + H]+
282.1606, found 282.1606.
University, and the Doctoral Scientific Research Founda-
tion of Anhui Normal University (no. 2016XJJ110).
ORCID
2‐(1H‐Benzo[d]imidazol‐2‐yl)‐4,6‐di‐tert‐butylphenol (7e).
1H NMR (300 MHz, CDCl3, δ, ppm): 9.49 (s, 2H), 7.73 (s, 1H),
7.41–7.47 (m, 3H), 7.27–7.30 (m, 2H), 1.50 (s, 9H), 1.37
(s, 9H). 13C NMR (75 MHz, CDCl3, δ, ppm): 156.0, 152.5,
140.5, 137.8, 126.9, 124.5, 123.4, 122.8, 118.6, 111.1, 110.4,
35.3, 34.4, 31.6, 29.5. HRMS (APCI) calcd for [C21H26N2O
+ H]+ 323.2123, found 323.2124.
Xinwei He http://orcid.org/0000-0002-1974-2464
Yongjia Shang http://orcid.org/0000-0001-9873-9150
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This work was partially supported by the National
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21772001), the Natural Science Foundation of Education
Administration of Anhui Province (no. KJ2016A267), the
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SUPPORTING INFORMATION
Additional Supporting Information may be found online
in the supporting information tab for this article.
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How to cite this article: He X, Wu Y, Jin W,
Wang X, Wu C, Shang Y. Highly efficient AgNO3‐
catalyzed approach to 2‐(benzo[d]azol‐2‐yl)phenols
from salicylaldehydes with 2‐aminothiophenol,
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