Facile synthesis of 1-(arylimino)naphthalen-2(1H)-ones from anilines and 2-naphthols promoted by NaBr/K2S2O8/CAN

Article abstract of DOI:10.1080/00397911.2019.1568496

An efficient method has been developed for the synthesis of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-naphthols promoted by NaBr/K₂S₂O₈/Ce(NH₄)₂(NO₃)₆. Using this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields (17 examples, 70–92% yields). The reactions may proceed through the following steps: bromination of 2-naphthols by in-situ-generated bromine from NaBr and K₂S₂O₈ to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-2-ols with anilines to afford the corresponding amines, and subsequent oxidation of the amines into the products by Ce(NH₄)₂(NO₃)_6. These newly obtained α-imine ketones have great potentials for synthesis of special optical materials bearing naphthalene moiety.

Full text of DOI:10.1080/00397911.2019.1568496

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
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Facile synthesis of 1-(arylimino)naphthalen-2(1H)-
ones from anilines and 2-naphthols promoted by
NaBr/K S O /CAN
2
2 8
Fei Yu, Hui Xu, Abdullah M. Asiri, Hadi M. Marwani & Ze Zhang
To cite this article: Fei Yu, Hui Xu, Abdullah M. Asiri, Hadi M. Marwani & Ze Zhang (2019): Facile
synthesis of 1-(arylimino)naphthalen-2(1H)-ones from anilines and 2-naphthols promoted by NaBr/
K S O /CAN, Synthetic Communications, DOI: 10.1080/00397911.2019.1568496
2
2
8
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https://doi.org/10.1080/00397911.2019.1568496
Facile synthesis of 1-(arylimino)naphthalen-2(1H)-ones from
anilines and 2-naphthols promoted by NaBr/K S O /CAN
2
2 8
a
a
b
b
a
Fei Yu , Hui Xu , Abdullah M. Asiri , Hadi M. Marwani , and Ze Zhang
a
School of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu, P. R. China;
Chemistry Department Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
b
ABSTRACT
ARTICLE HISTORY
An efficient method has been developed for the synthesis of 1-(aryli-
mino)naphthalen-2(1H)-ones through the cascade reaction of anilines
Received 28 September 2018
2 2 8 4 2 3 6
and 2-naphthols promoted by NaBr/K S O /Ce(NH ) (NO ) . Using
KEYWORDS
this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was
obtained in good to excellent yields (17 examples, 70–92% yields).
The reactions may proceed through the following steps: bromination
Anilines; cerium(IV)
diammonium nitrate;
potassium persulfate; 1-
(arylimino)naphthalen-
2(1H)-ones; 2-naphthols
of 2-naphthols by in-situ-generated bromine from NaBr and K S O
2
2 8
to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-
-ols with anilines to afford the corresponding amines, and subse-
3 6.
quent oxidation of the amines into the products by Ce(NH (NO )
2
4
)
2
These newly obtained a-imine ketones have great potentials for syn-
thesis of special optical materials bearing naphthalene moiety.
GRAPHICAL ABSTRACT
R
1
R
1
Facile synthesis of
NH
2
N
NaBr, K
toluene, 80 oC, 1 h
2 2 8
S O , CAN
1
-(arylimino)naphthalen-2(1H)-ones
+
O
from anilines and 2-naphthols
R
2
OH
2 2 8
promoted by NaBr/K S O /CAN
R
2
1
6 examples
7
0-92% isolated yields
Introduction
It is well known that the a-H of naphthalen-2-ols is highly reactive for electrophilic sub-
stitution and many organic reactions can be easily accomplished in this position.
Therefore, naphthalen-2-ols are widely employed for the synthesis of organic com-
[
1–4]
pounds containing a naphthalene moiety.
It is also an important synthetic strategy
[
5]
toward organic materials bearing special optical properties.
Among the various
organic transformations from the a-H of naphthalen-2-ols, bromination reactions have
been most commonly investigated, as the formed bromides can be further used to form
[
6,7]
a large variety of C–C, C–N, and C–X bonds.
Particularly, the coupling of these bro-
mides with suitable amines is a powerful method for the synthesis of nitrogen-contain-
ing compounds bearing the naphthalene moiety, which are promising molecules for the
[
8,9]
development of functional luminescent materials.
Currently, bromination reactions
CONTACT Ze Zhang
zzhang@ahpu.edu.cn
School of Biological and Chemical Engineering, Anhui Polytechnic
University, Wuhu 241000, P. R. China.
Supplemental data for this article is available online at on the publisher’s website.
ß 2019 Taylor & Francis Group, LLC

2
F. YU ET AL.
are often accomplished from in-situ-generated bromine instead of traditional Br and
2
N-bromosuccinimide (NBS), among which NaBr/K S O is frequently employed owing
2
10–13]
2
8
[
to its low toxicity, low cost, and easy operation.
Therefore, we explored the reac-
tion of anilines and 2-naphthols in the presence of NaBr/K S O , and investigated the
2
2 8
subsequent cascade organic transformation by employing Ce(NH ) (NO ) , which is a
4
14–19]
2
3 6
[
widely used oxidant and a radical promoter in organic synthesis.
Herein, we wish to report research findings on the reactions of anilines with 2-naph-
thols promoted by NaBr/K S O /Ce(NH ) (NO ) . We developed a facile method for
2
2
8
4 2
3 6
the efficient synthesis of various 1-(arylimino)naphthalen-2(1H)-ones – a novel kind of
a-imine ketones which have great application potential in organic synthesis and materi-
[
20–25]
als science.
Results and discussion
Before the formal synthesis of 1-(phenylimino)naphthalen-2(1H)-one (3a), we first
chose the reaction of 4-methylaniline (1a) with 2-naphthol (2a) as the model reaction
to optimize the reaction conditions, the results of which are summarized in Table 1.
As shown in Table 1, we employed typical bromination reagents and oxidants in
ꢀ
fixed amounts (1.0 equiv.) by stirring in toluene at 80 C for 1 h (Entries 1–10). The
results indicate that individually employed NBS (Entry 1) or CAN (Entry 2) cannot
afford 1-(phenylimino)naphthalen-2(1H)-one (3a) at all, and NBS provides 1-bromo-
naphthalen-2-ol as the main product. When NBS and CAN are used together to pro-
mote this reaction, the desired product 3a is generated in 87% yield (Entry 3). This
remarkable result prompted us to explore greener and more efficient conditions to
accomplish this transformation. We first employed K S O in place of CAN; however,
2
2 8
only traces of 3a were generated (Entry 4). Next, we used NaBr/K S O ; however, again,
2
2 8
only a trace amount of 3a was obtained (Entry 5). Hence, NaBr/CAN cannot promote
the formation of 3a (Entry 6). Finally, when NaBr, K S O , and CAN were combined to
2
2 8
promote this reaction, the desired product 3a was generated in a nearly quantitatively
yield as high as 95% (Entry 7). Attempts to reduce the usage of CAN to 0.5 equiv.
ꢀ
(
Entry 9) and reaction temperature to 60 C (Entries 10 and 11) resulted in significantly
decreased yields. Other solvents were also investigated, including THF, EtOH, DMF,
and DMSO; however, these afforded rather poor results (Entries 11–14). The strong
polarity of these solvents may have hindered bromination. Overall, when equal amounts
of NaBr, K S O , and CAN were used in combination to promote this reaction in tolu-
2
2 8
ꢀ
ene at 80 C, the desired product 3a was obtained with the highest efficiency.
Theoretically, compound 3a can exist by adopting a Z or E configuration; however,
1
H NMR analysis shows that it exists almost exclusively in one configuration. Further
NOESY analysis demonstrates that it exists in the Z configuration, as there is no inter-
action between the two phenyl rings.
Under the optimized reaction condition, various anilines and several substituted 2-
naphthols were employed, and a series of structurally diverse 1-(arylimino)naphthalen-
2
(1H)-ones was obtained in moderate to good yields. All products were ambiguously
1
13
characterized by H NMR, C NMR, and HRMS analyses. The results are summarized
in Table 2.

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3
Table 1. Optimization of the reaction condition for synthesis of 1-(phenylimino)naphthalen-2(1H)-
a
one (3a) .
NH2
OH
N
Conditions
N
+
O
not
O
1a
2a
Temperature
Time
(h)
ꢀ
b
Entry
Catalyst (equiv.)
Solvent
( C)
Yield (%)
1
2
3
4
5
6
7
8
9
NBS (1.0)
CAN (1.0)
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
THF
80
80
80
80
80
80
80
80
60
1
1
1
1
1
1
1
1
1
4
1
1
1
1
0
0
NBS (1.0) þ CAN (1.0)
87
trace
trace
0
95
45
32
72
41
38
71
65
NBS (1.0) þ K
NaBr (1.0) þ K
2
S
2
O
8
(1.0)
(1.0)
2
S
2
O
8
NaBr (1.0) þ CAN (1.0)
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
NaBr (1.0) þ K
2
S
2
S
2
S
2
S
2
S
2
S
2
S
2
S
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
8
8
8
8
8
8
8
8
(1.0) þ CAN (1.0)
(1.0) þ CAN (0.5)
(1.0) þ CAN (1.0)
(1.0) þ CAN (1.0)
(1.0) þ CAN (1.0)
(1.0) þ CAN (1.0)
(1.0) þ CAN (1.0)
(1.0) þ CAN (1.0)
1
1
1
1
1
a
0
1
2
3
4
60
reflux
reflux
80
EtOH
DMF
DMSO
80
Reactions were carried out with 4-methylaniline (1.0 mmol), 2-naphthol (1.0 mmol) and designated promoter.
b
Rapidly determined by GC-MS analysis on the sample solution from prompt extraction of the reaction mixture.
Table 2 shows that all anilines bearing either electron-donating or electron-withdraw-
ing groups can efficiently afford the corresponding products, regardless of whether the
substituents are in the 2-, 3-, or 4-position. Anilines with electron-donating groups
exhibit slightly higher efficiency. For 2-naphthols, substituents such as Br and CN have
no obvious effect on the reactions. In addition, we also explored some aliphatic amines
including hexylamine and benzylamine; however, the corresponding product was hardly
obtained. Note that the obtained 1-(arylimino)naphthalen-2(1H)-ones existed as a mix-
ture of Z/E imines in most cases, wherein the Z isomer is dominant. The ratio of the
1
two isomers was determined through the integration of H NMR spectra. In contrast,
products 3a, 3 g, and 3o exist almost exclusively in the Z configuration. Hence, it is
apparent that the Z isomer is more favorable due to steric effects.
To explore the reaction mechanism for the formation of 1-(arylimino)naphthalen-
2(1H)-ones 3, we performed some controlled experiments as shown in Scheme 1.
First, 2-naphthol 2a was reacted with an equal equivalent of NaBr and K S O under
2
2 8
the standard reaction condition as discussed above. As expected, the corresponding bro-
minating product 4a was obtained in 93% yield. Subsequently, the isolated 1-bromo-
naphthalen-2-ol 4a was reacted with p-toluidine 1a in the presence of an equal
equivalent of CAN under the standard reaction condition, affording the expected prod-
uct 3a in 90% yield. Based on these results, we propose the following reaction mechan-
ism (Scheme 2), which may involve the following steps: (a) bromination of 2-naphthols
2
by in-situ-generated Br from NaBr and K S O to afford 1-bromonaphthalen-2-ols 4,
2 2 2 8
which may tautomerize into A; (b) coupling of A with anilines 1 promoted by CAN to
afford the corresponding amines B; (c) dehydrogenative oxidation of the amines by
CAN into the final products 3.

4
F. YU ET AL.
Table 2. Synthesis of 1-(arylimino)naphthalen-2(1H)-ones 3 from anilines 1 and 2-naphthols 2 pro-
a,b
moted by NaBr/K S O /CAN
.
2
2 8
R1
NH2
OH
N
NaBr, K S O , CAN
2
2
8
R1
+
R2
°
O
toluene, 80 C, 1 h
R2
1
2
3
Me
Me
OMe
Me
N
N
N
O
N
O
O
O
3
a: 92%
Z)
3b: 90%
(Z/E=85:15)
3c: 86%
(Z/E=85:15)
3d: 88%
(Z/E=76:24)
(
Cl
Br
Cl
Cl
N
N
N
N
O
O
O
O
3
e: 80%
3f: 84%
(Z/E=90:10)
3g: 79%
(Z)
3h: 77%
(Z/E=60:40)
(
Z/E=83:17)
Me
O
Cl
Me
Cl
N
N
N
N
O
O
O
Br
Br
Br
Br
3
i: 81%
3j: 78%
(Z/E=83:17)
3k: 76%
(Z/E=82:18)
3l: 77%
(Z/E=80:20)
(
Z/E=77:23)
Me
O
Me
Me
N
N
N
O
N
O
O
NC
NC
NC
NC
3
m: 85%
3n: 80%
(Z/E=91:9)
3o: 76%
(Z)
3p: 74%
(Z/E=70:30)
(
Z/E=69:31)
a
Reactions were carried out with anilines 1 (1.0 mmol), 2-naphthols 2 (1.0 mmol), NaBr (1.0 mmol), K
2
S
2
O
8
(1.0 mmol)
ꢀ
and CAN (1.0 mmol) in a sealed tube by stirring in toluene (8 mL) at 80 C for 1 h.
b
Isolated yields.

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SYNTHETIC COMMUNICATIONS
5
Br
N
NH2
OH
OH
NaBr, K S O
1a
O
2
2
8
toluene, 80
°
C, 1 h
CAN
°
toluene, 80 C, 1 h
4a
2
a
3
a
93%
9
0%
Scheme 1. Controlled experiments.
NaBr + K S O
2
2
8
Br
Br
OH
OH
O
Br2
R2
R2
R2
4
A
2
NH2
R1
CAN
NH
1
R1
R2
R1
N
CAN
O
O
R2
3
B
Scheme 2. Proposed mechanism for formation of 1-(arylimino)naphthalen-2(1H)-ones 3.
In summary, we have successfully developed a facile method for the efficient synthesis
of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-
naphthols promoted by NaBr/K S O /Ce(NH ) (NO ) . Using this protocol, a series of
2
2
8
4 2
3 6
1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields. This
protocol possesses the advantages of short reaction time, low cost, employment of inex-
pensive, easily available, and nontoxic catalysts, and simple methodology. These merits
make this method a new and green alternative for the synthesis of a-imine ketones
which have potential applications in organic synthesis and materials science.
Experimental
Instruments and reagents
NMR spectra were recorded on Bruker AV400 NMR spectrometer in CDCl . TMS was
3
used as an internal standard. Chemical shifts (d) and J values are reported in ppm and
Hz, respectively. GC-MS was conducted on a GC-MS-QP 2010 instrument (Shimadzu,

6
F. YU ET AL.
Kyoto, Japan) (Rtx-17, 30 m ꢁ 25 mm ID, film thickness 0.25 lm df) with column flow
ꢀ
ꢀ
ꢀ
rate of 2 mL/min and heating rate of 10 C/min rising from 70 C to 250 C.All melting
points were determined on a XT-4 binocular microscope (Beijing Tech Instrument Co.,
China) and are not corrected. Analytical TLC and column chromatography were per-
formed on silica gel GF254, and silica gel H60, respectively. All liquid anilines were fur-
ther purified in standard manners before use. All solid anilines and 2-naphthols were
purchased from Acros or Aldrich Chemical Co. and used without further purification.
All solvents were obtained from SCRC (Sinopharm Chemical Reagent Co., Ltd. China)
in AR grade and used without further purification.
General procedure for synthesis of 1-(arylimino)naphthalen-2(1H)-ones 3a–3q (3a
as an example)
A mixture of toluidine (1a, 1.0 mmol), 2-naphthol (2a, 1.0 mmol), NaBr (1.0 mmol),
K S O (1.0 mmol), CAN (1.0 mmol), and toluene (8 mL) in a 25 mL of sealed tube was
2
2 8
ꢀ
stirred at 80 C for 1 h. After completion of the reaction, the mixture was diluted with
water (30 mL) and extracted with ethyl acetate (3 ꢁ 30 mL). The combined organic
layers were washed with water and brine, dried over anhydrous Na SO and filtered.
2
4
Then the solvent was removed under reduced pressure to obtain crude product. Further
purification by flash column chromatography on silica gel with EtOAc/petroleum as the
eluent gave 3a in 92% yield.
(Z)-1-[(4-methylphenyl)imino]naphthalen-2(1H)-one(3a)
ꢀ
1
Yield: 92%; red solid, mp 130–132 C; H NMR (400 MHz, CDCl ) d (ppm) 8.63 (d,
3
J ¼ 8.4 Hz, 1 H, ArH), 7.75 (d, J ¼ 9.2 Hz, 1 H, ArH), 7.70 (d, J ¼ 8.4 Hz, 2 H, ArH), 7.65
(
7
d, J ¼ 8.0 Hz, 1 H, ArH), 7.58 (t, J ¼ 7.6 Hz, 1 H, ArH), 7.41 (t, J ¼ 7.6 Hz, 1 H, ArH),
13
.31 (d, J ¼ 8.4 Hz, 2 H, ArH), 6.95 (d, J ¼ 9.6 Hz, 1 H, ArH), 2.44 (s, 3 H, CH ). C
3
NMR (100 MHz, CDCl ) d (ppm) 168.7, 143.5, 139.0, 138.3, 133.5, 130.2, 129.8, 128.6,
3
1
28.5, 128.0, 125.3, 124.1, 121.6, 119.1, 21.3; HRMS (ESI) m/z calcd for C H NO
17 14
þ
(M þ H) : 248.1075, found: 248.1092.
1
-[(3-methylphenyl)imino]naphthalen-2(1H)-one(3b)
1
Yield: 90%; red solid; Z/E ¼ 85: 15; H NMR (400 MHz, CDCl ) d (ppm) 8.57 (d,
3
J ¼ 8.0 Hz, 1 H, ArH), 7.72 (d, J ¼ 9.6 Hz, 1 H, ArH), 7.59 (t, J ¼ 8.4Hz, 2 H, ArH), 7.55
(
(
(
d, J ¼ 8.0 Hz, 2 H, ArH), 7.42 (d, J ¼ 7.8 Hz, 1 H, ArH), 7.40 (q, J ¼ 8.2, 1 H, ArH), 7.13
13
d, J ¼ 7.6 Hz, 1 H, ArH), 6.88 (d, J ¼ 9.6 Hz, 1 H, ArH), 2.47 (s, 3 H, CH ). C NMR
3
100 MHz, CDCl ) d (ppm) 172.1, 144.6, 140.0, 139.6, 133.6, 130.0, 129.4, 128.8, 128.6,
3
1
28.3, 128.0, 125.7, 124.9, 121.7, 119.0, 115.9, 21.6; HRMS (ESI) m/z calcd for
þ
C H NO (M þ H) : 248.1075, found: 248.1079.
1
7
14

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7
1
-[(2-methylphenyl)imino]naphthalen-2(1H)-one(3c)
1
Yield: 86%; red solid; Z/E ¼ 85: 15; H NMR (400 MHz, CDCl ) d (ppm) 8.55 (d,
3
J ¼ 8.0 Hz, 1 H, ArH), 7.94 (d, J ¼ 8.4 Hz, 1 H, ArH), 7.75 (d, J ¼ 9.6 Hz, 1 H, ArH), 7.62
(
d, J ¼ 8.0 Hz, 1 H, ArH), 7.58 (t, J ¼ 7.6 Hz, 1 H, ArH), 7.48 (d, J ¼ 8.8 Hz, 1 H, ArH),
7
.44 (t, J ¼ 6.6 Hz, 2 H, ArH), 6.88 (d, J ¼ 9.6 Hz, 1 H, ArH), 2.52 (s, 3 H, CH ). 13C
3
NMR (100 MHz, CDCl ) d (ppm) 173.4, 141.7, 140.7, 133.8, 133.4, 130.9, 130.5, 130.4,
3
1
29.1, 128.8, 128.1, 126.1, 125.0, 121.7, 120.2, 117.2, 17.4; HRMS (ESI) m/z calcd for
þ
C H NO (M þ H) : 248.1075, found: 248.1091.
1
7
14
1
-[(2-methoxyphenyl)imino]naphthalen-2(1H)-one(3d)
1
Yield: 80%; red solid; Z/E ¼ 76: 24; H NMR (400 MHz, CDCl ) d (ppm) 8.49 (dd,
3
J ¼ 20.8, 8.0 Hz, 1 H, ArH), 8.09–7.87 (m, 1 H, ArH), 7.67 (d, J ¼ 9.6 Hz, 1 H, ArH),
7
.58–7.50 (m, 2 H, ArH), 7.38 (t, J ¼ 7.4 Hz, 1 H, ArH), 7.22 (t, J ¼ 4.0 Hz, 1 H, ArH),
.14–7.08 (m, 1 H, ArH), 7.01 (d, J ¼ 8.0 Hz, 1 H, ArH), 6.83–6.76 (m, 1 H, ArH), 4.03
7
(
1
3 3
3
s, 3 H, OCH ) C NMR (100 MHz, CDCl ) d (ppm) 177.0, 149.7, 140.9, 133.8, 132.2,
1
28.9, 128.7, 127.9, 127.0, 126.5, 125.8, 124.6, 121.7, 121.6, 115.9, 111.2, 56.0; HRMS
þ
(ESI) m/z calcd for C H NO (M þ H) : 264.1025, found: 264.1026.
1
7
14
2
1
-[(4-brominephenyl)imino]naphthalen-2(1H)-one(3e)
1
Yield: 80%; red solid; Z/E ¼ 83: 17; H NMR (400 MHz, CDCl ) d (ppm) 8.52 (d,
3
J ¼ 8.0 Hz, 1 H, ArH), 7.99 (d, J ¼ 8.8 Hz, 1 H, ArH), 7.83 (d, J ¼ 2.0 Hz, 1 H, ArH), 7.75
(
7
d, J ¼ 9.6 Hz, 1 H, ArH), 7.61 (d, J ¼ 7.6Hz, 2 H, ArH), 7.58 (d, J ¼ 8.6 Hz, 2 H, ArH),
.45 (t, J ¼ 7.2 Hz, 1 H, ArH), 6.86 (d, J ¼ 9.2 Hz, 1 H, ArH) 13C NMR (100 MHz,
CDCl ) d (ppm) 174.5, 141.6, 135.4, 133.2, 131.8, 129.3, 128.9, 128.4, 126.6, 125.3, 122.0,
3
þ
1
19.6, 118.7, 114.9; HRMS (ESI) m/z calcd for C H BrNO (M þ H) : 312.0024,
16
11
found: 312.0018.
1
-[(4-chlorinephenyl)imino]naphthalen-2(1H)-one(3f)
1
Yield: 84%; red solid; Z/E ¼ 90: 10; H NMR (400 MHz, CDCl ) d (ppm) 8.50 (d,
3
J ¼ 7.6 Hz, 1 H, ArH), 8.02 (d, J ¼ 8.8 Hz, 1 H, ArH), 7.73 (d, J ¼ 9.2 Hz, 1 H, ArH), 7.66
(
d, J ¼ 2.0 Hz, 1 H, ArH), 7.62–7.54 (m, 2 H, ArH), 7.47–7.40 (m, 2 H, ArH), 6.85 (d,
J ¼ 9.6 Hz, 1 H, ArH). 13C NMR (100 MHz, CDCl ) d (ppm) 173.81, 141.39, 133.19,
3
1
32.65, 132.14, 131.19, 129.22, 128.91, 128.38, 126.53, 125.12, 121.98, 118.00, 114.88;
þ
HRMS (ESI) m/z calcd for C H ClNO (M þ H) : 268.0529, found: 268.0540.
1
6
11
(Z)-1-[(3-chlorinephenyl)imino]naphthalen-2(1H)-one(3g)
ꢀ
1
Yield: 79%; red solid, mp 154–156 C; H NMR (400 MHz, CDCl ) d (ppm) 8.53 (d,
3
J ¼ 8.4 Hz, 1 H, ArH), 7.78 (t, J ¼ 2.0 Hz, 1 H, ArH), 7.74 (d, J ¼ 9.2 Hz, 1 H, ArH),
7
7
.66–7.56 (m, 2 H, ArH), 7.53 (d, J ¼ 7.2 Hz, 1 H, ArH), 7.44 (d, J ¼ 9.2 Hz, 1 H, ArH),
.40 (d, J ¼ 8.0 Hz, 1 H, ArH), 7.26 (d, J ¼ 8.8 Hz, 1 H, ArH), 6.85 (d, J ¼ 9.6 Hz, 1 H,
ArH). 13C NMR (100 MHz, CDCl ) d (ppm) 173.4, 145.7, 141.0, 135.7, 133.4, 130.6,
3

8
F. YU ET AL.
1
30.5, 129.2, 128.8, 128.2, 126.9, 126.2, 125.0, 121.9, 117.8, 116.9; HRMS (ESI) m/z calcd
þ
for C H ClNO (M þ H) : 268.0529, found: 268.0531.
1
6
11
1
-[(2-chlorinephenyl)imino]naphthalen-2(1H)-one(3h)
1
Yield: 77%; red solid; Z/E ¼ 60: 40; H NMR (400 MHz, CDCl ) d (ppm) 8.51 (dd,
3
J ¼ 15.3, 8.1 Hz, 1 H, ArH), 8.06 (dd, J ¼ 59.8, 9.2 Hz, 1 H, ArH), 7.73 (dd, J ¼ 9.6,
2
.0 Hz, 1 H, ArH), 7.62 (dd, J ¼ 19.9, 2.7 Hz, 1 H, ArH), 7.58 (d, J ¼ 3.0 Hz, 1 H, ArH),
.56–7.49 (m, 1 H, ArH), 7.49–7.43 (m, 1 H, ArH), 7.42 (d, J ¼ 7.6 Hz, 1 H, ArH), 7.21
7
(
13
td, J ¼ 7.9, 1.5 Hz, 1 H, ArH), 6.83 (dd, J ¼ 9.5, 5.6 Hz, 1 H, ArH). C NMR (100 MHz,
CDCl ) d (ppm) 175.8, 141.8, 141.5, 132.5, 131.3, 130.0, 129.2, 128.9, 128.0, 126.8, 126.5,
3
þ
1
2
25.8, 125.6, 122.1, 122.0, 117.0; HRMS (ESI) m/z calcd for C H ClNO (M þ H) :
16
11
68.0529, found: 268.0537.
6
-bromine-1-[(4-methylphenyl)imino]naphthalen-2(1H)-one(3i)
1
Yield: 81%; red solid; Z/E ¼ 77: 23; H NMR (400 MHz, CDCl ) d (ppm) 8.44 (d,
3
J ¼ 8.8 Hz, 1 H, ArH), 7.95 (d, J ¼ 8.4 Hz, 1 H, ArH), 7.77 (s, 1 H, ArH), 7.67 (d,
J ¼ 8.4 Hz, 1 H, ArH), 7.65–7.61 (m, 2 H, ArH), 7.51 (s, 1 H, ArH), 7.26 (d, J ¼ 8.4 Hz,
13
1
H, ArH), 6.97 (d, J ¼ 9.2 Hz, 1 H, ArH), 2.41 (s, 3 H, CH ). C NMR (100 MHz,
3
CDCl ) d (ppm) 168.6, 141.1, 139.6, 138.1, 133.6, 132.0, 131.6, 129.5, 125.4, 123.5, 119.6,
3
þ
1
19.4, 117.4, 117.0, 21.0; HRMS (ESI) m/z calcd for C H BrNO (M þ H) : 326.0181,
17
13
found: 326.0178.
6
-bromine-1-[(3-methylphenyl)imino]naphthalen-2(1H)-one(3j)
1
Yield: 78%; red solid; Z/E ¼ 83: 17; H NMR (400 MHz, CDCl ) d (ppm) 8.43 (d,
3
J ¼ 8.8 Hz, 1 H, ArH), 7.75 (s, 1 H, ArH), 7.66–7.61 (m, 2 H, ArH), 7.54 (d, J ¼ 7.6 Hz,
2
H, ArH), 7.38 (t, J ¼ 8.0 Hz, 1 H, ArH), 7.17 (d, J ¼ 7.6 Hz, 1 H, ArH), 6.92 (d,
13
J ¼ 9.6 Hz, 1 H, ArH), 2.48 (s, 3 H, CH ). C NMR (100 MHz, CDCl ) d (ppm) 170.0,
3
3
1
1
44.9, 139.7, 138.1, 132.2, 131.6, 130.6, 129.6, 129.5, 129.3, 129.0, 125.8, 123.5, 119.4,
þ
19.1, 116.3, 21.6; HRMS (ESI) m/z calcd for C H BrNO (M þ H) : 326.0181,
17
13
found: 326.0183.
6
-bromine-1-[(3-chlorinephenyl)imino]naphthalen-2(1H)-one(3k)
1
Yield: 76%; red solid; Z/E ¼ 82: 18; H NMR (400 MHz, CDCl ) d (ppm) 8.35 (t,
3
J ¼ 9.8 Hz, 1 H, ArH), 7.72 (dd, J ¼ 16.9, 3.8 Hz, 2 H, ArH), 7.63 (d, J ¼ 10.4 Hz, 2 H,
ArH), 7.53 (d, J ¼ 8.0 Hz, 1 H, ArH), 7.41 (t, J ¼ 8.0 Hz, 1 H, ArH), 7.30 (d, J ¼ 4.0 Hz,
13
1
H, ArH), 6.89 (dd, J ¼ 9.5, 2.6 Hz, 1 H, ArH). C NMR (100 MHz, CDCl ) d (ppm)
3
1
1
71.1, 145.9, 139.0, 135.7, 134.5, 131.9, 130.8, 130.6, 130.0, 129.5, 127.6, 125.8, 123.6,
þ
19.7, 118.2, 117.5; HRMS (ESI) m/z calcd for C H BrClNO (M þ H) : 345.9634,
16
10
found: 345.9645.

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R
SYNTHETIC COMMUNICATIONS
9
6
-bromine-1-[(2-chlorinephenyl)imino]naphthalen-2(1H)-one(3l)
1
Yield: 77%; red solid; Z/E ¼ 80: 20; H NMR (400 MHz, CDCl ) d (ppm) 8.30 (dd,
3
J ¼ 21.5, 8.7 Hz, 1 H, ArH), 8.04 (d, J ¼ 8.8 Hz, 1 H, ArH), 7.69 (s, 1 H, ArH), 7.59 (dd,
J ¼ 9.3, 3.2 Hz, 2 H, ArH), 7.47 (d, J ¼ 8.0 Hz, 1 H, ArH), 7.41 (t, J ¼ 7.6 Hz, 1 H, ArH),
13
7
.22 (t, J ¼ 8.2 Hz, 1 H, ArH), 6.84 (t, J ¼ 8.8 Hz, 1 H, ArH). C NMR (100 MHz,
CDCl ) d (ppm) 173.7, 140.7, 139.5, 132.0, 131.9, 130.9, 130.7, 130.1, 129.5, 128.0, 127.5,
3
þ
1
3
26.6, 125.2, 123.6, 120.0, 117.0; HRMS (ESI) m/z calcd for C H BrClNO (M þ H) :
16
10
45.9634, found: 345.9637.
6
-cyano-1-[(4-methylphenyl)imino]naphthalen-2(1H)-one(3m)
1
Yield: 85%; red solid; Z/E ¼ 69: 31; H NMR (400 MHz, CDCl ) d (ppm) 8.70 (dd,
3
J ¼ 18.7, 8.6 Hz, 1 H, ArH), 8.38–8.31 (m, 1 H, ArH), 7.92–7.76 (m, 2 H, ArH), 7.73 (d,
J ¼ 8.2 Hz, 2 H, ArH), 7.62–7.56 (m, 1 H, ArH), 7.34 (d, J ¼ 8.2 Hz, 1 H, ArH), 7.11 (d,
1
3
J ¼ 9.2 Hz, 1 H, ArH), 2.46 (s, 3 H, CH ). C NMR (100 MHz, CDCl ) d (ppm) 166.3,
3
3
1
1
44.0, 140.2, 136.9, 135.9, 134.6, 133.5, 131.7, 130.4, 129.6, 125.3, 123.7, 122.6, 120.1,
þ
12.9, 21.5; HRMS (ESI) m/z calcd for C H N O (M þ H) : 273.1028,
18
13 2
found: 273.1019.
6
-cyano-1-[(3-methylphenyl)imino]naphthalen-2(1H)-one(3n)
1
Yield: 80%; red solid; Z/E ¼ 91: 9; H NMR (400 MHz, CDCl ) d (ppm) 8.66 (d,
3
J ¼ 8.8 Hz, 1 H, ArH), 7.97 (s, 1 H, ArH), 7.76–7.70 (m, 2 H, ArH), 7.58 (d, J ¼ 6.4 Hz,
2
1
H, ArH), 7.41 (t, J ¼ 8.2 Hz, 1 H, ArH), 7.24–7.16 (m, 1 H, ArH), 7.04 (d, J ¼ 9.6 Hz,
13
H, ArH), 2.49 (s, 3 H, CH ). C NMR (100 MHz, CDCl ) d (ppm) 169.4, 145.0, 139.9,
3 3
1
37.7, 136.1, 133.4, 130.0, 130.0, 129.6, 129.1, 127.3, 126.1, 122.6, 120.0, 119.1, 116.9,
þ
108.5, 21.5; HRMS (ESI) m/z calcd for C H N O (M þ H) : 273.1028,
18
13 2
found: 273.1039.
(Z)-6-cyano-1-[(2-methylphenyl)imino]naphthalen-2(1H)-one(3o)
ꢀ
1
Yield: 76%; red solid, mp 156–158 C; H NMR (400 MHz, CDCl ) d (ppm) 8.67 (d,
3
J ¼ 10.0 Hz, 1 H, ArH), 8.38–8.31 (m, 1 H, ArH), 8.05–7.80 (m, 4 H, ArH), 7.77–7.54 (m,
13
3
H, ArH), 7.35–7.01 (m, 1 H, ArH), 2.59 (s, 3 H, CH ). C NMR (100 MHz, CDCl ) d
3 3
(
1
2
ppm) 171.2, 163.3, 149.7, 142.7, 138.1, 134.6, 133.4, 131.7, 131.4, 129.1, 127.7, 127.5,
þ
26.2, 123.7, 122.5, 116.1, 112.8, 17.6; HRMS (ESI) m/z calcd for C H N O (M þ H) :
18
13 2
73.1028, found: 273.1032.
6
-cyano-1-(phenyl)iminonaphthalen-2(1H)-one(3p)
1
Yield: 74%; red solid; Z/E ¼ 70: 30; H NMR (400 MHz, CDCl ) d (ppm) 8.69 (dd,
3
J ¼ 8.6, 5.2 Hz, 1 H, ArH), 8.39–8.32 (m, 1 H, ArH), 7.87 (d, J ¼ 17.8 Hz, 1 H, ArH),
7
(
.83–7.77 (m, 2 H, ArH), 7.75 (d, J ¼ 8.4 Hz, 1 H, ArH), 7.60–7.52 (m, 2 H, ArH), 7.42
13
t, J ¼ 8.4 Hz, 1 H, ArH), 7.09 (dd, J ¼ 17.2, 8.2 Hz, 1 H, ArH). C NMR (100 MHz,
CDCl ) d (ppm) 169.2, 145.2, 137.8, 136.1, 134.6, 133.4, 131.7, 130.1, 129.8, 129.1, 127.5,
3

1
0
F. YU ET AL.
1
27.3, 126.0, 122.6, 119.6, 112.8, 108.6; HRMS (ESI) m/z calcd for C H N O
17
11 2
þ
(M þ H) : 259.0871, found: 259.0860.
Funding
We gratefully acknowledge the National Natural Science Foundation of China [No. 21242013] for
financial support.
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