Iodine-promoted 2-arylsulfanylphenol formation using cyclohexanones as phenol source

Article abstract of DOI:10.1039/c4ra08014a

A novel method for the formation of 2-arylsulfanylphenols using cyclohexanones as phenol source via dehydrogenation is described. Various aromatic sodium sulfinates and sulfonyl chlorides acted as efficient coupling partners to construct new C-S bonds in the presence of an iodine promoter.

Full text of DOI:10.1039/c4ra08014a

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Iodine-promoted 2-arylsulfanylphenol formation
using cyclohexanones as phenol source†
Cite this: RSC Adv., 2014, 4, 44621
a
a
a
a
ab
*
Ya Chen, Fuhong Xiao, Hui Chen, Saiwen Liu and Guo-Jun Deng
Received 2nd August 2014
Accepted 5th September 2014
A novel method for the formation of 2-arylsulfanylphenols using cyclohexanones as phenol source via
dehydrogenation is described. Various aromatic sodium sulfinates and sulfonyl chlorides acted as
efficient coupling partners to construct new C–S bonds in the presence of an iodine promoter.
DOI: 10.1039/c4ra08014a
www.rsc.org/advances
2-arylsulfanylphenols.13 In 2010, Pan and co-workers reported
an efficient protocol for the preparation of 2-arylsulfanylphe-
Introduction
nols from thiophenols and aromatic halides via a copper-cata-
lyzed tandem transformation of C–S coupling/C–H
hydroxylation (Scheme 1c).14 Although there are other few
methods available for 2-arylsulfanylphenol preparation,15 all of
the above-mentioned approaches require two aromatic
coupling partners. Aryl thioether preparation from non-
aromatic coupling partners is still rare.16
Recently, the Stahl group reported a palladium-catalyzed
procedure to convert non-aromatic cyclohexanones into
phenols or cyclohexenones via dehydrogenation strategy under
mild reaction conditions using oxygen as the sole oxidant.17 We
Aryl thioethers are important structural motifs which are widely
present in agrochemicals, functional materials, naturally
occurring compounds and pharmaceutical products.1 There-
fore, the development of efficient methods for the preparation
of aryl thioethers has stimulated considerable interest.2 Over
the past several decades, the transition-metal catalyzed cross-
coupling reaction of aryl halides with various sulfenylating
agents has proved to be powerful method for the construction of
new C–S bond. With the tremendous developments in the C–S
bond formation, thiols have been the most-popular sulfenylat-
ing reagents in the preparation of aryl thioethers.3 In recent
years, the direct sulfenylation of C–H bonds has attracted great
interest since this method can potentially lead to more efficient
synthesis with a reduced number of synthetic operations.
Various sulfenylating agents such as thiols,4 disuldes,5
sulfonyl chlorides,6 sulfenyl halides,7 sodium sulnates8 and
sulfonyl hydrazides9 were successfully employed to couple with
electron-rich (hetero)-arenes.
Among various thioether derivatives, 2-arylsulfanylphenols
play an important role in biologically and pharmaceutically
active molecules due to they also contain a phenol structural
motif.10 However, procedures for preparation of aryl thioethers
with a hydroxyl group at the ortho position are still rare, and
the majors are based on the metal-catalyzed cross-coupling
of thiols with 2-halophenols (Scheme 1a).11 Deprotection
of the corresponding methoxy aryl thioethers provided
an alternative procedure for 2-arylsulfanylphenols (Scheme
1b).12 Oxidation of the C–H or C–halogen bond ortho to aryl
thioethers afforded another efficient procedure for substituted
aKey Laboratory of Environmentally Friendly Chemistry and Application of Ministry of
Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China.
E-mail: gjdeng@xtu.edu.cn; Fax: +86-0731-5829-2251; Tel: +86-0731-5829-8601
bKey Laboratory of Molecular Recognition and Function, Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100080, China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c4ra08014a
Scheme 1 Various procedures for 2-arylsulfanylphenol preparation.
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and others successfully used cyclohexanones as aryl sources for (entries 2–4). When 20 mol% of iodine was used, the desired
C–C,18 C–N19 and C–O20 bond formation. We and Wei's group product was obtained in 88% yield (entry 4). Other organic
also found that 2-arylsulfanylphenols could be generated from solvents were also tested and all of them were less efficient for
cyclohexanones using thiophenols or disuldes as the sulfur this kind of transformation (entries 5–10). It's necessary to use
sources in the presence of iodine catalyst.21 Nevertheless, these 20 mol% of iodine to get satisfactory yield, and the reaction
sulfenylating agents possess unpleasant odors or are expensive. yield decreased to 53% when the catalyst loading was decreased
Moreover, they suffer from a narrow substrate scope. Cyclo- to 10 mol% (Table 1, entry 11). The reaction temperature also
hexanones are cheap, readily available, and able to convert into affected the reaction yield signicantly, and only 68% yield was
other important organic materials.22 Thus, cyclohexanones can observed when the reaction was carried out at 130 ꢀC (entry 12).
be used as an ideal aryl source for coupling reaction via dehy- Interestingly, slight lower yields were detected when the reac-
drogenation strategy. Due to the importance of 2-arylsulfanyl- tion were run under oxygen or argon atmosphere (Table 1,
phenols in pharmaceutical drugs and other biologically active entry 13–14).
compounds, it's highly desirable to develop reliable and general
With the optimized reaction conditions in hand, we rst
procedures for preparation of them using readily available investigated the substrate scope with respect to cyclohexanones
starting materials. As our continuing efforts using cyclohexa- as shown in Table 2. Cyclohexanones bearing an alkyl group at
nones as aryl source for coupling reactions, herein, we describe the para position were able to smoothly react with 2a to give the
the iodine-promoted 2-arylsulfanylphenol formation from desired products (3aa–3fa) in good yields. Besides alkyl
cyclohexanones using aryl sulfonyl chlorides and sodium sul- substituted cyclohexanones, aryl substituted cyclohexanones
nates as the sulfur sources (Scheme 1d).
such as 4-phenylcyclohexanone (1g) and 4-(4-hydroxyphenyl)-
Results and discussion
Table 2 Reaction of p-toluenesulfonyl chloride (2a) with various
Firstly, we started our study by using cyclohexanone (1a) and
p-toluenesulfonyl chloride (2a) as the model substrates to get
the optimized reaction conditions. The desired product 3aa was
detected only in trace amount when the reaction was carried out
in 1,4-dioxane at 150 ꢀC under air atmosphere in the absence of
catalyst (Table 1, entry 1). Subsequently, several iodide-con-
taining catalysts were investigated under similar reaction
conditions, and among them iodine showed the best efficiency
cyclohexanonesa
Table 1 Optimization of the reaction conditionsa
Entry
Catalyst
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
NMP
DMA
Diglyme
Toluene
Trace
18
37
88
50
26
14
6
Kl
NIS
l2
l2
l2
l2
l2
9
l2
l2
l2
l2
l2
l2
Dibutyl ether
Anisole
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
20
8
53
68
76
70
10
11c
12d
13e
14f
a
Conditions: 1a (0.2 mmol), 2a (0.24 mmol), catalyst (20 mol%), solvent
b
c
a
(0.5 mL), 150 ꢀC, 18 h, under air. GC yield. Catalyst (10 mol%).
Conditions: 1 (0.5 mmol), 2a (0.6 mmol), I2 (0.1 mmol), 1,4-dioxane
d
130 ꢀC. e Under argon. f Under oxygen.
(1.0 mL), 150 ꢀC, 18 h, air; isolated yield.
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cyclohexanone (1h) also participated well in this process, and proceeded to give the desired products (3ab–3ae) in good to
gave the corresponding products 3ga and 3ha in 87% and 84% excellent yields. In general, introduction of strong electron-
yields, respectively. To our delight, the ester functional group withdrawing substituents into the arylsulfonyl chlorides
was well tolerated in this reaction, and the corresponding signicantly decreased reaction yields, partially due to more
product 3ia was obtained in 75% yield. When 3-methyl- side reactions occurred (3ai–3ak). It was noteworthy that
cyclohexanone was used, two isomers were obtained in a halogen substituents such as uoro (2f) and bromo (2g) were
combination yield of 76% (3ja : 3ja' ¼ 3 : 1). The substituent well tolerated in this kind of transformation, and the corre-
position in cyclohexanone profoundly affected the reaction sponding functionalized products (3af and 3ag) could be used
yield, and only a trace amount of product could be detected as substrates for further functionalization. More bulky
when 2-methylcyclohexanone was used.
substrates such as naphthalene-1-sulfonyl chloride (2m) and
To further explore the scope and the limitation of the reac- naphthalene-2-sulfonyl chloride (2n) gave the corresponding
tion, various aromatic sulfonyl chlorides (2) were treated with products (3am and 3an) in 73% and 79% yields, respectively.
cyclohexanone (1a) under the optimized conditions (Table 3). Congested 2,4,6-trimethylbenzene-1-sulfonyl chloride (2l) also
The reaction with arylsulfonyl chlorides bearing electron- could smoothly react with 1a to give the product (3al) in 75%
donating groups at the aromatic ring (2b–2e) smoothly yield. To our delight, aliphatic sulfonyl chloride (2q) and
heterocyclic sulfonyl chloride (2p) also could react with cyclo-
hexanone to give the products (3aq and 3ap) in moderate yields.
Aer screening various sulfonyl chlorides, we next sought to
Table 3 Reaction of cyclohexanone (1a) with various sulfonyl
chloridesa
expand the scope of sulfenylation of cyclohexanones with
sulfonyl chlorides to sodium sulnates. These compounds are
more stable and moisture-insensitive compared to sulfonyl
chlorides. Unfortunately, only trace amount of the desired
product (5aa) was observed when p-toluenesulnic acid sodium
reacted with cyclohexanone (1a) under the previously optimized
reaction conditions for sulfonyl chlorides. To get the best
reaction conditions for sodium sulnate substrates, we rein-
vestigated the reaction conditions for this kind of trans-
formation. Aer systematic investigation, we found that diethyl
phosphite and iodine both were necessary. When p-toluene-
sulnic acid sodium (4a) reacted with cyclohexanone at 130 ꢀC
under an argon atmosphere, the desired product 5aa was
obtained in 71% yield (Table 4). Various substituted cyclohex-
anones and arylsulnic acid sodium salts were used under the
optimized conditions, and the corresponding 2-arylsulfonyl-
phenols were obtained in good to high yields. Cyclohexanones
bearing alkyl or aryl substituents were smoothly transformed
into the corresponding products (5ba–5ha). To our delight,
functional groups such as acetamido, uoro, chloro, and bromo
were well tolerated to give the corresponding products (5ia, 5ac–
5ae) in good yields. However, much lower yields were obtained
when sodium 4-(triuoromethyl)benzenesulnate (4f) and
sodium 2-methylbenzenesulnate (4g) were employed for this
kind of reaction. Unfortunately, aliphatic sodium sulnates
such as sodium methanesulnate and sodium ethanesulnate
were not suitable for this kind of transformation under the
current reaction conditions.
Although the exact mechanism for 2-arylsulfanylphenol
formation from cyclohexanones and sulfonyl chlorides was not
well understood at this stage, we proposed a plausible mecha-
nism for this transformation on the basis of our previous
observations and literature6 (Fig. 1). Reduction of sulfonyl
chloride (2a) with iodine generates intermediate A and IOꢁ.
Electrophilic attack of A on the cyclohexanone ring yields
intermediate 2-(phenylthio)cyclohexanone (B) with the release
of the acidic HCl. Finally, dehydrogenation–tautomerization of
B affords the nal product 3ab and regenerates the iodine
catalyst.
a
Conditions: 1a (0.5 mmol), 2 (0.6 mmol), I2 (0.1 mmol), 1,4-dioxane
(1.0 mL), 150 ꢀC, 18 h, air; isolated yield.
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Table 4 Reaction of various sodium sulfinates with cyclohexanonesa
Fig. 2 Plausible mechanism for sodium sulfinate substrate.
of intermediate 1 with the aid of I2 gives the desired product 5ab
(3ab) and HI.16,21a Then part of HI reacts with the S]O bond of
DMSO to give intermediate 2, which is followed by protonation
of the oxygen atom to give intermediate 3. Another portion of
the HI nucleophilically attacks on the iodide atom of 3 to
regenerate I2 with the formation of dimethylsulfane and
water.5e,27 A control experiment was carried out using phenyl
sulfoxide as the oxidant, and diphenylsulfane was observed by
GC-MS.8a This means DMSO was possibly reduced to dime-
thylsulfane during the reaction process.
a
Conditions: 1 (0.2 mmol), 4 (0.6 mmol), I2 (0.06 mmol), diether
phosphite (2 equiv.), DMSO (0.1 mL), toluene (0.5 mL), 130 ꢀC, 24 h,
under argon; isolated yield.
Conclusions
In summary, we have developed an iodine-promoted approach
for the synthesis of 2-arylsulfanylphenols using cyclohexanones
as a reliable phenol source under transition-metal-free condi-
tions. Iodine was used as an effective catalyst in this trans-
formation. Various sulfonyl chlorides and sodium sulnates
were used as the sulfur source to smoothly couple with cyclo-
hexanones. The C–S bond formation, dehydrogenation and
tautomerization were realized in one-pot in the absence of
transition-metals. Since sulfonyl chlorides and sulnic acid
sodium salts are readily available starting materials, this
method affords an efficient approach for 2-arylsulfanylphenols
with a broad range of functional groups. The scope, mechanism
and synthetic applications of this reaction are under
investigation.
Fig. 1 Plausible mechanism for sulfonyl chloride substrate.
Experimental section
General methods
A plausible mechanism for sodium sulnate substrates was
also proposed (Fig. 2). Reaction of 4b with diethyl phosphite
and I2 generates an electrophilic species PhSI,8 which can attack
1a to give an intermediate 1. Dehydrogenation–tautomerization
Flash column chromatography was performed over silica gel
48–75 mm. Unless otherwise noted, 1H NMR and 13C NMR
spectra were recorded on Bruker-AV (400 and 100 MHz,
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respectively) instrument internally referenced to SiMe4 or 130.1, 127.3, 116.5, 115.3, 33.3, 24.2, 21.0; MS (EI) m/z (%) 258,
chloroform signals. MS analyses were performed on Agilent 243 (100), 151, 123, 91, 79; HRMS calcd for: C16H17OS [M ꢁ H]ꢁ:
5975 GC-MS instrument (EI). The new compounds were char- 257.0995, found 257.0999.
acterized by 1H NMR, 13C NMR, MS and HRMS. The structure of
4-Pentyl-2-(p-tolylthio)phenol (3ea):.21a Pale yellow liquid;
known compounds were further corroborated by comparing yield 78%; 1H NMR (400 MHz, CDCl3, ppm) d 7.32 (s, 1H), 7.16
their 1H NMR, 13C NMR data and MS data with those of litera- (d, J ¼ 8.0 Hz, 1H), 7.06–6.96 (m, 5H), 6.36 (s, 1H), 2.53 (t, J ¼ 8.0
ture. Reagents were used as received or prepared by our Hz, 2H), 2.28 (s, 3H), 1.61–1.57 (m, 2H), 1.33–1.27 (m, 4H), 0.88
laboratory.
(t, J ¼ 6.0 Hz, 3H); 13C NMR (100 MHz, CDCl3, ppm) d 155.2,
136.2, 136.1, 135.8, 132.6, 132.1, 130.0, 127.4, 116.6, 115.3, 34.9,
31.4, 31.3, 22.6, 21.0, 14.0; MS (EI) m/z (%) 286, 229 (100), 137,
91, 77, 65.
General procedure (3aa)
The reaction mixture of cyclohexanone (1a, 52 mL, 0.5 mmol),
p-toluenesulfonyl chloride (2a, 114 mg, 0.6 mmol), iodine
(25.4 mg, 0.1 mmol) and 1,4-dioxane (1 mL) in a 10 mL oven-
dried reaction vessel was stirred at 150 ꢀC for 18 h under an air
atmosphere. Aer cooling to room temperature, the volatiles
were removed under reduced pressure. The residue was puried
by column chromatography on silica gel (petroleum ether/
EtOAc ¼ 95 : 5) to yield the desired product 3aa as pale yellow
liquid (88.6 mg, 82% yield).
4-(tert-Pentyl)-2-(p-tolylthio)phenol (3fa):.21a Pale yellow
liquid; yield 78%; 1H NMR (400 MHz, CDCl3, ppm) d 7.46
(s, 1H), 7.33 (d, J ¼ 8.0 Hz, 1H), 7.05 (d, J ¼ 8.0 Hz, 2H), 6.98 (t, J
¼ 8.0 Hz, 3H), 6.34 (s, 1H), 2.28 (s, 3H), 1.63–1.59 (m, 2H), 1.25
(s, 6H), 0.67 (t, J ¼ 6.0 Hz, 3H); 13C NMR (100 MHz, CDCl3, ppm)
d 154.8, 142.4, 136.0, 134.3, 132.6, 130.0, 129.9, 126.9, 115.9,
114.9, 37.5, 37.0, 28.6, 20.9, 9.2; MS (EI) m/z (%) 286, 257 (100),
134, 91, 77, 65.
3-(p-Tolylthio)-[1,10-biphenyl]-4-ol (3ga):.21a Pale yellow solid;
yield 87%; mp 56–58 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 7.78
(s, 1H), 7.61–7.53 (m, 3H), 7.41 (d, J ¼ 8.0 Hz, 2H), 7.31 (t, J ¼ 8.0
General procedure (5aa)
Iodine (15.3 mg, 0.06 mmol) and p-toluenesulnic acid sodium Hz, 1H), 7.14–7.06 (m, 5H), 6.55 (s, 1H), 2.28 (s, 3H); 13C NMR
(4a, 107 mg, 0.6 mmol) were added to a 10 mL oven-dried (100 MHz, CDCl3, ppm) d 156.7, 140.0, 136.5, 135.1, 134.6,
reaction vessel. The reaction vessel was purged with argon for 132.2, 130.8, 130.2, 129.0, 127.8, 127.2, 126.8, 118.0, 116.0, 21.1;
three times and was added diether phosphite (50 mL, 0.4 mmol), MS (EI) m/z (%) 292 (100), 172, 139, 91, 77, 65.
cyclohexanone (1a, 21 mL, 0.2 mmol), DMSO (0.1 mL) and
3-(p-Tolylthio)-[1,10-biphenyl]-4,40-diol (3ha). White solid;
toluene (0.5 mL) by syringe. The reaction mixture was stirred at yield 84%; mp 119–121 ꢀC; 1H NMR (400 MHz, CDCl3, ppm)
130 ꢀC for 24 h. Aer cooling to room temperature, the volatiles d 7.71–7.70 (m, 1H), 7.54–7.52 (m, 1H), 7.41 (d, J ¼ 8.0 Hz, 2H),
were removed under reduced pressure. The residue was puried 7.11–7.06 (m, 5H), 6.87 (d, J ¼ 8.0 Hz, 2H), 6.50 (s, 1H), 4.81
by column chromatography on silica gel (petroleum ether/ (s, 1H), 2.28 (s, 3H); 13C NMR (100 MHz, DMSO-d6, ppm) d 157.0,
EtOAc ¼ 98 : 2) to yield the desired product 5aa as pale yellow 155.5, 136.8, 132.8, 132.0, 131.0, 130.8, 130.4, 130.2, 127.5,
liquid (30.6 mg, 71% yield). The product is same as 3aa.
127.1, 121.5, 116.5, 116.2, 21.1; MS (EI) m/z (%) 308 (100), 281,
2-(p-Tolylthio)phenol (3aa, CAS: 59010-83-2):.21a 1H NMR 207, 188, 91, 28; HRMS calcd for: C19H15O2S [M ꢁ H]ꢁ:
(400 MHz, CDCl3, ppm) d 7.52 (d, J ¼ 8.0 Hz, 1H), 7.35 (t, J ¼ 8.0 307.0787, found 307.0791.
Hz, 1H), 7.06–7.00 (m, 5H), 6.93 (t, J ¼ 6.0 Hz, 1H), 6.53 (s, 1H),
Ethyl 4-hydroxy-3-(p-tolylthio)benzoate (3ia):.21a Pale yellow
2.28 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm) d 157.1, 136.7, solid; yield 75%; mp 72–74 ꢀC; 1H NMR (400 MHz, CDCl3, ppm)
136.3, 132.2, 132.1, 130.0, 127.5, 121.2, 117.2, 115.5, 21.0; MS d 8.27 (s, 1H), 8.05 (d, J ¼ 8.0 Hz, 1H), 7.09–7.03 (m, 5H), 6.95
(EI) m/z (%) 216 (100), 201, 183, 96, 91.
(s, 1H), 4.34 (q, J ¼ 6.7 Hz, 2H), 2.29 (s, 3H), 1.38 (t, J ¼ 6.0 Hz,
4-Methyl-2-(p-tolylthio)phenol (3ba):.21a Pale yellow liquid; 3H); 13C NMR (100 MHz, CDCl3, ppm) d 165.7, 160.8, 138.4,
yield 80%; 1H NMR (400 MHz, CDCl3, ppm) d 7.33 (s, 1H), 7.16 136.8, 133.5, 131.3, 130.2, 128.1, 123.7, 118.2, 115.4, 61.0, 21.0,
(d, J ¼ 8.0 Hz, 1H), 7.06–7.01 (m, 4H), 6.95 (d, J ¼ 8.0 Hz, 1H), 14.4; MS (EI) m/z (%) 288 (100), 260, 243, 171, 91, 63.
6.36 (s, 1H), 2.28 (s, 6H); 13C NMR (100 MHz, CDCl3, ppm)
2-(Phenylthio)phenol (3ab, CAS: 55214-86-3):.13 Pale yellow
d 155.0, 136.7, 136.2, 132.8, 132.5, 130.5, 130.1, 127.6, 116.8, liquid; yield 65%; 1H NMR (400 MHz, CDCl3, ppm) d 7.54 (d, J ¼
115.3, 21.0, 20.4; MS (EI) m/z (%) 230 (100), 197, 110, 91, 77, 65. 8.0 Hz, 1H), 7.38 (t, J ¼ 8.0 Hz, 1H), 7.24–7.22 (m, 2H), 7.17–7.13
4-Ethyl-2-(p-tolylthio)phenol (3ca):.21a Pale yellow liquid; (m, 1H), 7.09–7.07 (m, 3H), 6.96 (t, J ¼ 8.0 Hz, 1H), 6.52 (s, 1H);
yield 70%; 1H NMR (400 MHz, CDCl3, ppm) d 7.35 (s, 1H), 7.19 13C NMR (100 MHz, CDCl3, ppm) d 157.3, 136.9, 135.9, 132.3,
(d, J ¼ 8.0 Hz, 1H), 7.06–6.97 (m, 5H), 6.36 (s, 1H), 2.58 (q, J ¼ 8.0 129.2, 127.0, 126.2, 121.3, 116.5, 115.6; MS (EI) m/z (%) 202
Hz, 2H), 2.28 (s, 3H), 1.21 (t, J ¼ 8.0 Hz, 3H); 13C NMR (100 MHz, (100), 169, 141, 96, 77, 51.
CDCl3, ppm) d 155.2, 137.1, 136.2, 135.6, 132.5, 131.6, 130.0,
2-((4-Ethylphenyl)thio)phenol (3ac). Pale yellow liquid; yield
127.5, 116.8, 115.4, 27.9, 21.0, 15.8; MS (EI) m/z (%) 244 (100), 83%; 1H NMR (400 MHz, CDCl3, ppm) d 7.52 (d, J ¼ 8.0 Hz, 1H),
229, 211, 124, 91, 77.
7.36 (t, J ¼ 8.0 Hz, 1H), 7.08–7.02 (m, 5H), 6.94 (t, J ¼ 8.0 Hz, 1H),
4-(Iso-propyl)-2-(p-tolylthio)phenol (3da). Pale yellow liquid; 6.55 (s, 1H), 2.61–2.55 (m, 2H), 1.18 (d, J ¼ 8.0 Hz, 3H); 13C NMR
yield 72%; 1H NMR (400 MHz, CDCl3, ppm) d 7.37 (s, 1H), 7.22 (100 MHz, CDCl3, ppm) d 157.2, 142.7, 136.7, 132.4, 132.0,
(d, J ¼ 8.0 Hz, 1H), 7.06–6.97 (m, 5H), 6.35 (s, 1H), 2.88–2.82 128.8, 127.6, 121.1, 117.3, 115.5, 28.3, 15.4; MS (EI) m/z (%) 230
(m, 1H), 2.28 (s, 3H), 1.22 (d, J ¼ 8.0 Hz, 6H); 13C NMR (100 (100), 215, 105, 91, 77, 63; HRMS calcd for: C14H13OS [M ꢁ H]ꢁ:
MHz, CDCl3, ppm) d 155.2, 141.8, 136.1, 134.4, 132.5, 130.3, 229.0682, found 229.0686.
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2-((4-(tert-Butyl)phenyl)thio)phenol (3ad, CAS: 2976-28-5):.23
2-(Mesitylthio)phenol (3al). Pale yellow solid; yield 75%; mp
1
Pale yellow liquid; yield 85%; H NMR (400 MHz, CDCl3, ppm) 61–63 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 7.08 (t, J ¼ 8.0 Hz,
d 7.53 (d, J ¼ 8.0 Hz, 1H), 7.37 (t, J ¼ 8.0 Hz, 1H), 7.28–7.26 1H), 6.96 (s, 2H), 6.90 (d, J ¼ 8.0 Hz, 1H), 6.84 (d, J ¼ 8.0 Hz, 1H),
(m, 2H), 7.08–7.03 (m, 3H), 6.95 (t, J ¼ 8.0 Hz, 1H), 6.55 (s, 1H), 6.74 (t, J ¼ 6.0 Hz, 1H), 5.84 (s, 1H), 2.39 (s, 6H), 2.29 (s, 3H); 13
C
1.27 (s, 9H); 13C NMR (100 MHz, CDCl3, ppm) d 157.3, 149.5, NMR (100 MHz, CDCl3, ppm) d 154.1, 142.9, 139.1, 129.9, 129.7,
136.9, 132.3, 132.2, 127.0, 126.4, 121.3, 116.9, 115.6, 34.5, 31.3; 127.9, 122.2, 121.4, 115.4, 110.0, 21.9, 21.1; MS (EI) m/z (%) 244,
MS (EI) m/z (%) 258, 243 (100), 125, 108, 97, 77.
150, 120 (100), 105, 91, 77; HRMS calcd for: C15H15OS [M ꢁ H]ꢁ:
2-((4-Methoxyphenyl)thio)phenol (3ae):.21a Pale yellow solid; 243.0838, found 243.0842.
yield 64%; mp 62–64 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 7.50
2-(Naphthalen-1-ylthio)phenol (3am). Pale yellow solid; yield
(d, J ¼ 8.0 Hz, 1H), 7.32 (t, J ¼ 8.0 Hz, 1H), 7.13 (d, J ¼ 8.0 Hz, 73%; mp 87–89 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 8.35 (d, J
2H), 7.03 (d, J ¼ 8.0 Hz, 1H), 6.91 (t, J ¼ 8.0 Hz, 1H), 6.80 (d, J ¼ ¼ 8.0 Hz, 1H), 7.87 (d, J ¼ 8.0 Hz, 1H), 7.67 (d, J ¼ 8.0 Hz, 1H),
8.0 Hz, 2H), 6.57 (s, 1H), 3.76 (s, 3H); 13C NMR (100 MHz, CDCl3, 7.63–7.54 (m, 3H), 7.41 (t, J ¼ 6.0 Hz, 1H), 7.30–7.28 (m, 1H),
ppm) d 159.0, 156.8, 136.1, 131.6, 130.3, 126.2, 121.2, 118.8, 7.11 (d, J ¼ 8.0 Hz, 1H), 6.99 (t, J ¼ 8.0 Hz, 1H), 6.90 (d, J ¼ 8.0
115.5, 115.1, 55.4; MS (EI) m/z (%) 232 (100), 217, 171, 108, 96. Hz, 1H), 6.46 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) d 157.4,
2-((4-Fluorophenyl)thio)phenol (3af):.21a Pale yellow liquid; 136.9, 134.1, 133.0, 132.2, 131.4, 128.8, 126.9, 126.7, 126.5,
yield 80%; 1H NMR (400 MHz, CDCl3, ppm) d 7.51 (d, J ¼ 8.0 Hz, 126.0, 124.6, 124.0, 121.6, 116.3, 115.9; MS (EI) m/z (%) 252, 189,
1H), 7.37 (t, J ¼ 8.0 Hz, 1H), 7.11–7.06 (m, 3H), 6.97–6.93 128 (100), 115, 77; HRMS calcd for: C16H11OS [M ꢁ H]ꢁ:
(m, 3H), 6.49 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) d 161.7 251.0525, found 251.0530.
(d, J ¼ 243.0 Hz), 157.1, 136.6, 132.3, 130.9 (d, J ¼ 3.0 Hz), 129.3
2-(Naphthalen-2-ylthio)phenol (3an):.21a Pale yellow liquid;
(d, J ¼ 8.0 Hz), 121.4, 117.1, 116.4 (d, J ¼ 22.0 Hz), 115.7; MS (EI) yield 79%; 1H NMR (400 MHz, CDCl3, ppm) d 7.77–7.58 (m, 4H),
m/z (%) 220, 128, 96 (100), 75, 61.
7.48–7.40 (m, 4H), 7.24–7.21 (m, 1H), 7.11 (d, J ¼ 8.0 Hz, 1H),
2-((4-Bromophenyl)thio)phenol (3ag, CAS: 1254831-59-8):.21a 6.99 (t, J ¼ 8.0 Hz, 1H), 6.54 (s, 1H); 13C NMR (100 MHz, CDCl3,
1
Pale yellow liquid; yield 70%; H NMR (400 MHz, CDCl3, ppm) ppm) d 157.4, 136.9, 133.8, 133.2, 132.3, 131.9, 129.0, 127.8,
d 7.51 (d, J ¼ 8.0 Hz, 1H), 7.42–7.34 (m, 3H), 7.08 (d, J ¼ 8.0 Hz, 127.2, 126.8, 125.9, 125.4, 125.3, 121.4, 116.6, 115.8; MS (EI) m/z
1H), 6.99–6.92 (m, 3H), 6.42 (s, 1H); 13C NMR (100 MHz, CDCl3, (%) 252, 219, 128 (100), 115, 77.
ppm) d 157.3, 136.9, 135.2, 132.7, 132.3, 128.4, 121.6, 120.0,
115.8, 115.8; MS (EI) m/z (%) 282, 280, 201, 168, 96 (100).
2-((4-Bromo-3-uorophenyl)thio)phenol (3ao). Pale yellow
liquid; yield 56%; 1H NMR (400 MHz, CDCl3, ppm) d 7.51 (d, J ¼
2-((4-(Triuoromethoxy)phenyl)thio)phenol
(3ah).
Pale 8.0 Hz, 1H), 7.45–7.38 (m, 2H), 7.10 (d, J ¼ 8.0 Hz, 1H), 7.00 (t, J
yellow liquid; yield 66%; 1H NMR (400 MHz, CDCl3, ppm) d 7.53 ¼ 8.0 Hz, 1H), 6.77–6.74 (m, 2H), 6.35 (s, 1H); 13C NMR (100
(d, J ¼ 8.0 Hz, 1H), 7.41 (t, J ¼ 8.0 Hz, 1H), 7.10–7.08 (m, 5H), MHz, CDCl3, ppm) d 159.4 (d, J ¼ 248.0 Hz), 157.3, 138.0 (d, J ¼
6.98 (d, J ¼ 8.0 Hz, 1H), 6.45 (s, 1H); 13C NMR (125 MHz, CDCl3, 6.0 Hz), 136.9, 133.9, 133.0, 123.4 (d, J ¼ 4.0 Hz), 121.7, 116.1,
ppm) d 157.3, 147.6, 136.9, 134.7, 132.7, 128.0, 121.9, 121.6, 115.0, 114.7 (d, J ¼ 25.0 Hz), 106.4 (d, J ¼ 21.0 Hz); MS (EI) m/z
120.4 (q, J ¼ 256.0 Hz), 115.8, 115.7; MS (EI) m/z (%) 286 (100), (%) 300 (100), 218, 186, 109, 96, 63; HRMS calcd for: C12H7-
201, 171, 128, 96; HRMS calcd for: C13H8O2F3S [M ꢁ H]ꢁ: BrFOS [M ꢁ H]ꢁ: 296.9380, found 296.9382.
285.0192, found 285.0195.
2-(Thiophen-2-ylthio)phenol (3ap). Pale yellow solid; yield
2-((4-(Triuoromethyl)phenyl)thio)phenol (3ai). Pale yellow 43%; mp 39–41 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 7.52 (d, J
liquid; yield 46%; 1H NMR (400 MHz, CDCl3, ppm) d 7.53 (d, J ¼ ¼ 8.0 Hz, 1H), 7.30–7.29 (m, 2H), 7.15 (s, 1H), 7.00–6.87 (m, 3H),
8.0 Hz, 1H), 7.48–7.43 (m, 3H), 7.12 (d, J ¼ 8.0 Hz, 3H), 7.01 (t, J 6.48 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) d 156.0, 134.9,
¼ 8.0 Hz, 1H), 6.37 (s, 1H); 13C NMR (125 MHz, CDCl3, ppm) 133.6, 132.1, 131.5, 129.1, 127.6, 121.2, 120.4, 115.7; MS (EI) m/z
d 157.4, 141.2, 137.1, 133.0, 128.1 (q, J ¼ 32.0 Hz), 126.1, 126.0 (%) 208 (100), 175, 147, 96, 84, 71; HRMS calcd for: C10H7OS2 [M
(q, J ¼ 3.7 Hz), 124.0 (q, J ¼ 270.0 Hz), 121.7, 116.0, 114.5; MS ꢁ H]ꢁ: 206.9933, found 206.9935.
(EI) m/z (%) 270 (100), 251, 171, 96, 69; HRMS calcd for:
2-(Ethylthio)phenol (3aq, CAS: 29549-60-8):.26 Pale yellow
liquid; yield 43%; 1H NMR (400 MHz, CDCl3, ppm) d 7.47 (d, J ¼
C
13H8OF3S [M ꢁ H]ꢁ: 269.0243, found 269.0247.
2-((4-Nitrophenyl)thio)phenol (3aj):.24 Yellow solid; yield 8.0 Hz, 1H), 7.32–7.26 (m, 1H), 6.99 (d, J ¼ 8.0 Hz, 1H), 6.88 (t, J
36%; mp 99–101 ꢀC; 1H NMR (400 MHz, CDCl3, ppm) d 8.09 (d, J ¼ 6.0 Hz, 1H), 6.77 (s, 1H), 2.72 (q, J ¼ 8.0 Hz, 2H), 1.22 (t, J ¼ 6.0
¼ 8.0 Hz, 2H), 7.54–7.46 (m, 2H), 7.15–7.11 (m, 3H), 7.04 (t, J ¼ Hz, 3H); 13C NMR (100 MHz, CDCl3, ppm) d 157.1, 136.1, 131.1,
8.0 Hz, 1H), 6.25 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) 120.7, 118.8, 114.7, 30.8, 14.9; MS (EI) m/z (%) 154 (100), 139,
d 157.5, 145.9, 137.1, 133.4, 126.5, 126.0, 124.4, 124.2, 121.9, 126, 97, 53.
116.3; MS (EI) m/z (%) 247 (100), 230, 200, 171, 97.
4-Methyl-2-(p-tolylthio)phenol (5ba):.21a Pale yellow liquid;
4-((2-Hydroxyphenyl)thio)benzonitrile (3ak):.25 Pale yellow yield 75%. The product is same as 3ba.
solid; yield 42%; mp 82–84 ꢀC; 1H NMR (400 MHz, CDCl3, ppm)
4-Ethyl-2-(p-tolylthio)phenol (5ca):.21a Pale yellow liquid;
d 7.52–7.44 (m, 4H), 7.13–7.07 (m, 3H), 7.02 (t, J ¼ 8.0 Hz, 1H), yield 83%. The product is same as 3ca.
6.29 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) d 157.5, 143.5,
4-(Iso-propyl)-2-(p-tolylthio)phenol (5da). Pale yellow liquid;
137.1, 133.3, 132.8, 132.6, 126.7, 126.3, 121.8, 118.5, 116.2; MS yield 81%. The product is same as 3da.
(EI) m/z (%) 227 (100), 198, 166, 96, 63.
4-Pentyl-2-(p-tolylthio)phenol (5ea):.21a Pale yellow liquid;
yield 83%. The product is same as 3ea.
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4-(tert-Pentyl)-2-(p-tolylthio)phenol (5fa):.21a Pale yellow
RSC Advances
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liquid; yield 85%. The product is same as 3fa.
3-(p-Tolylthio)-[1,10-biphenyl]-4-ol (5ga):.21a Pale yellow solid;
yield 80%. The product is same as 3ga.
3-(p-Tolylthio)-[1,10-biphenyl]-4,40-diol (5ha). White solid;
yield 68%. The product is same as 3ha.
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N-(4-Hydroxy-3-(p-tolylthio)phenyl)acetamide (5ia):.21a Pale
yellow liquid; yield 50%; 1H NMR (400 MHz, CDCl3, ppm) d 7.62
(s, 1H), 7.48 (d, J ¼ 8.0 Hz, 1H), 7.05–6.99 (m, 6H), 6.38 (s, 1H),
2.28 (s, 3H), 2.14 (s, 3H); 13C NMR (100 MHz, CDCl3, ppm)
d 168.5, 153.8, 136.6, 131.7, 131.2, 130.1, 128.1, 128.0, 124.5,
117.9, 115.6, 24.2, 21.0; MS (EI) m/z (%) 273 (100), 231, 207, 139,
111, 91.
2-(Phenylthio)phenol (5ab, CAS: 55214-86-3):.13 Pale yellow
liquid; yield 64%. The product is same as 3ab.
2-((4-Fluorophenyl)thio)phenol (5ac):.21a Pale yellow liquid;
yield 75%. The product is same as 3af.
2-((4-Chlorophenyl)thio)phenol (5ad, CAS: 59010-71-8):.21a
1
Pale yellow liquid; yield 70%; H NMR (400 MHz, CDCl3, ppm)
d 7.51 (d, J ¼ 8.0 Hz, 1H), 7.39 (t, J ¼ 8.0 Hz, 1H), 7.19 (t, J ¼ 8.0
Hz, 2H), 7.09–6.95 (m, 4H), 6.43 (s, 1H); 13C NMR (100 MHz,
CDCl3, ppm) d 157.2, 136.8, 134.5, 132.5, 132.3, 129.3, 128.3,
121.4, 116.2, 115.8; MS (EI) m/z (%) 236 (100), 220, 200, 168, 96.
2-((4-Bromophenyl)thio)phenol (5ae, CAS: 1254831-59-8):.21a
Pale yellow liquid; yield 68%. The product is same as 3ag.
2-((4-(Triuoromethyl)phenyl)thio)phenol (5af). Pale yellow
liquid; yield 42%. The product is same as 3ai.
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2-(o-Tolylthio)phenol (5ag):.21a Pale yellow liquid; yield 56%;
1H NMR (400 MHz, CDCl3, ppm) d 7.48 (d, J ¼ 8.0 Hz, 1H), 7.39
(t, J ¼ 8.0 Hz, 1H), 7.17 (d, J ¼ 8.0 Hz, 1H), 7.09–6.95 (m, 4H),
6.66 (d, J ¼ 8.0 Hz, 1H), 6.40 (s, 1H), 2.45 (s, 3H); 13C NMR (100
MHz, CDCl3, ppm) d 157.4, 136.8, 135.7, 134.9, 134.9, 132.0,
130.4, 126.8, 126.2, 126.0, 121.4, 115.6, 20.0; MS (EI) m/z (%) 216
(100), 201, 122, 96, 91.
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Acknowledgements
This work was supported by the National Natural Science
Foundation of China (21172185, 21372187), the Hunan
¨
H. Hatoum-Mokdad, G. Konig, R. Sibley, J. Witowsky and
Provincial
Innovative
Foundation
for
Postgraduate
S. Wong, Bioorg. Med. Chem. Lett., 1999, 9, 2531.
(CX2013B269), the New Century Excellent Talents in University
from Ministry of Education of China (NCET-11-0974) and the
Research Fund for the Doctoral Program of Higher Education of
China, Ministry of Education of China (20124301110005).
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