Catalyst-free C-S/C-O bond formation: Synthesis of novel 4-thio-substituted 2-aryl-4H-chromenes from easily available 2-hydroxychalcones

Article abstract of DOI:10.1016/j.tet.2013.01.047

An efficient catalyst-free synthesis of novel functionalized 4-thio-substituted 2-aryl-4H-chromenes from easily available 2-hydroxychalcone derivatives is described. This domino reaction enables successful assembly of two new C-S and C-O sigma bonds in a one-pot operation.

Full text of DOI:10.1016/j.tet.2013.01.047

Tetrahedron 69 (2013) 2430e2435
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Catalyst-free CeS/CeO bond formation: synthesis of novel
4-thio-substituted 2-aryl-4H-chromenes from easily available
2-hydroxychalcones
*
Guo-Dong Yin , Ting-Ting Lai, Zhi-Si Yan, Han Chen, Jing Zheng, Qing Tao
Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, College of Chemistry and Environmental Engineering, Hubei Normal University,
Huangshi 435002, China
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient catalyst-free synthesis of novel functionalized 4-thio-substituted 2-aryl-4H-chromenes from
easily available 2-hydroxychalcone derivatives is described. This domino reaction enables successful
assembly of two new CeS and CeO sigma bonds in a one-pot operation.
Ó 2013 Elsevier Ltd. All rights reserved.
Received 1 November 2012
Received in revised form 12 January 2013
Accepted 15 January 2013
Available online 26 January 2013
Keywords:
Domino reaction
2-Hydroxychalcones
Thio-substituted
4H-Chromenes
Catalyst-free
1. Introduction
of 2-amino-4-(phenylthio)-4H-chromene-3-carbonitriles by a Mi-
chael addition reaction of iminochromene with thiophenols
Chromenes and chromans are important classes of heterocyclic
compounds, which constitute the key cores of various natural
(Scheme 1a).9 Singh found that this transformation could be ach-
ieved by a one-pot three-component reaction of salicylaldehyde,
malononitrile, and thiophenols in ionic liquid.10 Recently, Zhu also
developed a route for the synthesis of thio-substituted chromenes
by the reaction of 2-(trifluoromethyl)-2-hydroxy-2H-chromenes
with thiophenols promoted by Lewis acid (Scheme 1b).11 However,
thio-substituted chromenes with an aryl group at C-2 position are
not easily accessible by currently existing routes. Consequently, in
order to expand the chromene library, the development of new and
more general methods for their preparation is of significant in-
terest. In addition, catalyst-free synthetic methods have attracted
much interest owing to reduced pollution, mild conditions, ease of
purification, and lower costs. Encouraged by the synthesis of fla-
vones involving the intramolecular cyclization of 2-hydroxyphenyl-
3-phenylpropane-1,3-dione intermediate12 and as a continuation
of our efforts toward the development of new synthetic protocols
for the construction of heterocyclic frameworks,13 we herein report
an efficient strategy for the preparation of novel 4-thio-substituted
2-aryl-4H-chromenes from easily available starting materials 2-
hydroxychalcones without any catalyst (Scheme 1c).
products. For example, 4-thio-substituted chromans 4
ioether-epicatechin (1), 4 -2-aminoethylthiolepicatechin (2), and
-2-hydroxyethylthioepicatechin (3) are widely present in plants,
b-benzylth-
b
4b
including edible vegetables and fruits (Fig. 1).1 They also exhibit
a wide of range of biological activities.2 In recent years, function-
alized chromenes and chromans have played an ever-increasing
role in the synthetic approaches toward promising compounds in
the field of medicinal chemistry.3e7 To data, only few examples for
the synthesis of 4-thio-substituted chromenes have been re-
ported.8 Magedov described an efficient method for the synthesis
Fig. 1. Examples of natural products.
2. Results and discussion
Initially, 2-hydroxychalcone derivatives (4) were synthesized
* Corresponding author. Tel./fax: þ86 714 6515602; e-mail address: gdyin@
hbnu.edu.cn (G.-D. Yin).
according to the known methods.14 Next, an attempted reaction of
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.01.047

G.-D. Yin et al. / Tetrahedron 69 (2013) 2430e2435
2431
Table 2
Synthesis of 4-(4-chlorophenylthio)-substituted 4H-chromenes
Scheme 1. Strategies for the synthesis of thio-substituted chromenes.
2-hydroxychalcone (4a) with 4-chlorobenzenethiol (5a) was carried
out to gain the desired product 4-(4-chlorophenylthio)-2-phenyl-4H-
chromene (6a) in various solvents under catalyst-free conditions.
Preliminary experiment indicated that in refluxing THF, MeCN, and
MeOH, product 6a was not observed (Table 1, entries 1e3). No re-
Table 1
Optimization of the reaction conditions for the synthesis of 6a
a All reactions were performed using 4 (0.5 mmol), 5a (0.55 mmol) in toluene (3.0 mL).
b Isolated yield.
6d was further confirmed by X-ray diffraction analysis (Fig. 2).15 This
transformation was also suitable for heterocyclic substrates (furan
and thiophene), furnishing 6e and 6f in 72% and 75% yields, re-
spectively. However, the alkyl group (eCH3) substrate resulted in
a complex reaction mixture and a trace amount of product 6g was
not isolated. Moreover, the reaction of (E)-3-(5-chloro-2-hydroxy-
phenyl)-1-phenylprop-2-en-1-one (R1¼Cl) with 5a also gave rise to
6h in 75% yield.
Entrya
Solvent
Temp (ꢀC)
4a/5ab
Yieldc (%)
1
2
3
4
5
6
7
8
THF
Reflux
Reflux
Reflux
100
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1.1
1:1.5
1:1
d
d
d
d
d
40
8
12
10
20
76
80
80
20
MeCN
MeOH
DMSO
DMF
100
EtOH
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
80
n-PrOH
t-BuOH
DCE
Benzene
Toluene
Toluene
Toluene
Toluene
9
10
11
12
13
14
a
All reactions were performed using 4a (0.5 mmol) in solvent (3.0 mL) for 6 h.
Molar ratio of 4a/5a.
Isolated yield.
b
c
actions occurred in DMSO and DMF at 100 ꢀC (Table 1, entries 4, 5).
The reaction gave 6a in 40% yield using EtOH as the solvent (Table 1,
entry 6). When n-PrOH, t-BuOH, benzene, and 1,2-dichloroethane
(DCE) were employed, the reactions delivered the product in a low
yield (Table 1, entries 7e10). We were pleased to find that the re-
action proceeded smoothly in refluxing toluene for 6 h to provide
product 6a in 76% yield (Table 1, entry 11). The yield increased to 80%
when 1.1 equiv of 5a was used (Table 1, entry 12), but it could not be
further improved as increasing the ratio of 4a/5a to 1.5 (Table 1, entry
13). While the temperature decreased to 80 ꢀC, the similar result was
obtained as in refluxing benzene (Table 1, entry 14).
Fig. 2. X-ray crystal structure of compound 6d.
With the optimal reaction conditions (1.1 equiv of thiol, toluene,
at reflux) in hand, the reactions of 5a with various 2-hyroxychalcone
derivatives were explored to gauge the generality of this process
(Table 2). For the substrates bearing electron-donating (eOMe) and
electron-withdrawing groups (eCl, eF) on the phenyl ring (R2), the
reactions proceeded smoothly to give the corresponding 4-thio-
substituted 4H-chromenes 6bed in 68e78% yields. The structure of
Then, we further extended the substrates to a variety of thiols
for the preparation of structurally diverse and functionalized 4-
thio-substituted 4H-chromenes (Table 3). The experimental re-
sults indicated that the treatments of 4a with aryl thiols including
electron-deficient 3-fluorobenzenethiol and electron-rich 4-tert-
butylbenzenethiol could give the corresponding products 6i and 6j
in 75% and 70% yields, respectively. In addition, heteroaryl thiols,

2432
G.-D. Yin et al. / Tetrahedron 69 (2013) 2430e2435
Table 3
Synthesis of various 4-thio-substituted 2-aryl-4H-chromenes 6a,b
Fig. 3. Possible reaction pathway for the present reaction.
(see Supplementary data). Subsequently, the expected thio-
substituted 4H-chromene 6a was obtained after loss of water of 6ab.
3. Conclusion
In summary, we have developed an efficient, catalyst-free syn-
thesis of novel 4-thio-substituted-2-aryl-4H-chromenes by the
reactions of 2-hydroxychalcone derivatives with various thiols. This
domino reaction enables successful assembly of two new CeS and
CeO sigma bonds in a one-pot operation. Moreover, due to easily
accessible starting materials, wide scope of substrates, and good
yields, we believe that this new synthetic approach has potential in
the synthesis of various functionalized 4H-chromenes, which are of
considerable interest as potential biologically active compounds or
pharmaceuticals.
4. Experimental
4.1. General method
All chemicals were commercial and used without further puri-
fication. All organic solvents were dried and freshly distilled before
use. 1H and 13C NMR spectra were recorded on Bruker AV 300 MHz
spectrometers using CDCl3 as the solvent. Chemical shifts are re-
ported relative to TMS (internal standard). IR spectra were obtained
as KBr, cmꢁ1 pellet samples on a Nicolet 5700 FTIR spectrometer.
The X-ray crystal structure determinations of compounds were
obtained on a Bruker SMART APEX CCD system. Flash column
chromatography was performed on silica gel (200e300 mesh).
High-resolution mass spectra were recorded on Bruker micrOTOF-
QII (ESI) and Waters GCT Premier (EI and CI). After careful attempt
of different ion sources, such as ESI, EI, CI and APCI (Thermo LCQ TM
Deca XP plus), the CeS bond (chromenes-C4) cleavages were still
observed for some compounds. HRMS (CI) data of two fragments
for those CeS bond cleavage compounds were given.
a All reactions were performed using 4 (0.5 mmol), 5 (0.55 mmol) in toluene (3.0 mL).
b Isolated yields. c n-Dodecane-1-thiol (1.0 mmol) was employed for 10 h.
such as 5-(4-tert-butylphenyl)-1,3,4-oxadiazole-2-thiol and 5-(2-
chlorophenyl)-1,3,4-oxadiazole-2-thiol also afforded 6k and 6l in
good yields. Nevertheless, the reaction of 4a with aliphatic thiol (n-
dodecane-1-thiol) was slower than those aromatic substrates.
When 2.0 equiv of n-dodecane-1-thiol was used and the reaction
time was prolonged to 10 h, 6m was isolated in 73% yield. This
probably reflected the lower nucleophilicity of the aliphatic thiol. In
addition, other 2-hyroxychalcone derivatives (4) could also react
with various thiols, furnishing the desired products 6nex in
70e85% yields.
The possible reaction mechanism was proposed using 4a as an
example, as shown in Fig. 3. First, under catalyst-free reaction con-
ditions, 4a reacted with 4-chlorobenzenethiol (5a) via a Michael
addition reaction to form the saturated intermediate thio-
substituted ketone (6aa),16 which was successfully isolated from
the reaction mixture in refluxing toluene for 15 min. Then isomeri-
zation of 6aa gave rise to the formation of the chroman ring (hem-
iketal) 6ab. It was notably that 1H NMR spectroscopy showed up as
a mixture of ketone and hemiketal with an approximate molar ratio
4.2. General experimental procedure for the synthesis of
4-thio-substituted-4H-chromenes (6)
A mixture of 4 (0.5 mmol) and thiols (5) (0.55 mmol) was heated at
reflux in anhydrous toluene (3.0 mL). After the reactant disappeared
(6e10 h, monitored by thin layer chromatography), the mixture was
cooled to room temperature. The reaction mixture was directly added
to the column chromatography using petroleum ether as the eluent to
remove toluene, then eluting with petroleum ether or petroleum
ether/ethyl acetate to give the expected compounds 6.
17
of 20:1 in CDCl3 and only ketone form was observed in DMSO-d6

G.-D. Yin et al. / Tetrahedron 69 (2013) 2430e2435
2433
4.3. Characterization data
C
15H11ClOþC6H4ClS, 242.0498þ142.9722, found: 242.0513þ142.
9725.
4.3.1. 4-(4-Chlorophenylthio)-2-phenyl-4H-chromene
(6a). Mp
87e88 ꢀC; IR (KBr, cmꢁ1) 2358, 1230, 1086, 816, 679; 1H NMR
4.3.8. 4-(3-Fluorophenylthio)-2-phenyl-4H-chromene (6i). Yellow
(300 MHz, CDCl3)
d
(ppm) 7.58e7.54 (m, 2H), 7.41e7.36 (m, 4H),
oil; IR (KBr, cmꢁ1) 2354, 1641, 1226, 1003, 876, 686; 1H NMR
7.19e6.99 (m, 6H), 6.87 (d, J¼8.1 Hz, 1H), 5.62 (d, J¼5.0 Hz, 1H), 5.15
(300 MHz, CDCl3) d (ppm) 7.57e7.53 (m, 2H), 7.38e7.32 (m, 4H),
(d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d
(ppm) 152.1, 150.9,
7.19e7.06 (m, 3H), 6.92e6.81 (m, 4H), 5.61 (d, J¼5.0 Hz, 1H), 5.17 (d,
137.5, 135.1, 133.6, 129.7, 129.5, 128.9, 128.41, 128.40, 128.3, 124.8,
123.8, 119.9, 116.4, 97.1, 45.9; HRMS-EI: m/z calcd for C21H15ClOS:
350.0532, found: 350.0528.
J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d (ppm) 162.0 (d,
1JCeF¼247.2 Hz), 152.0, 150.9, 133.7 (d, 3JCeF¼7.7 Hz), 133.6, 131.4 (d,
3
4JCeF¼3.0 Hz), 129.4, 129.3 (d, JCeF¼8.3Hz), 128.9, 128.5, 128.3,
2
124.8, 123.8, 122.3 (d, JCeF¼21.2 Hz), 119.8, 116.4, 115.4 (d,
4.3.2. 4-(4-Chlorophenylthio)-2-(4-methoxyphenyl)-4H-chromene
2JCeF¼20.9 Hz), 97.1, 45.8; HRMS-EI: m/z calcd for C21H15FOS:
(6b). Mp 63e64 ꢀC; IR (KBr, cmꢁ1) 2358, 1647, 1610, 1244, 1026,
334.0828, found: 334.0811.
817, 649; 1H NMR (300 MHz, CDCl3)
d
(ppm) 7.50 (d, J¼6.9 Hz, 2H),
7.37 (d, J¼7.5 Hz, 1H), 7.18e7.00 (m, 6H), 6.91e6.85 (m, 3H), 5.51
4.3.9. 4-(4-tert-Butylphenylthio)-2-phenyl-4H-chromene
(d, J¼5.0 Hz, 1H), 5.14 (d, J¼5.0 Hz, 1H), 3.84 (s, 3H); 13C NMR
(6j). Yellow oil; IR (KBr, cmꢁ1) 2959, 1638, 1231, 1013, 825, 691; 1H
(75 MHz, CDCl3)
d
(ppm) 160.2, 152.1, 150.9, 137.4, 135.0, 129.9,
NMR (300 MHz, CDCl3) d (ppm) 7.81e7.74 (m, 4H), 7.50e7.35 (m,
129.5, 128.4, 128.3, 126.3, 126.2, 123.7, 120.0, 116.4, 113.7, 95.5, 55.3,
46.1; HRMS-EI: m/z calcd for C22H17ClO2S: 380.0638, found:
380.0632.
7H), 7.26e7.24 (m, 1H), 7.13 (t, J¼7.5 Hz, 1H), 6.95 (d, J¼4.7 Hz, 1H),
5.71 (d, J¼4.7 Hz, 1H), 1.29 (s, 9H); 13C NMR (75 MHz, CDCl3)
d
(ppm) 175.6, 159.7, 156.0, 153.1, 151.7, 133.3, 130.0, 129.6, 128.8,
128.5, 126.5, 125.9, 125.3, 124.3, 119.6, 117.2, 116.8, 93.0, 53.0, 35.1,
4.3.3. 2-(4-Chlorophenyl)-4-(4-chlorophenylthio)-4H-chromene
31.0; HRMS-EI: m/z calcd for C25H24OS: 372.1548, found: 372.1555.
(6c). Mp 72e73 ꢀC; IR (KBr, cmꢁ1) 2358, 1646, 1231, 1006, 825, 665;
1H NMR (300 MHz, CDCl3)
d
(ppm) 7.49 (d, J¼8.6 Hz, 2H), 7.41e7.33
4.3.10. 2-(4-tert-Butylphenyl)-5-(2-phenyl-4H-chromen-4-yl-thio)-
(m, 3H), 7.22e7.05 (m, 4H), 6.98 (d, J¼8.3 Hz, 2H), 6.86 (d, J¼8.1 Hz,
1,3,4-oxadiazole (6k). Mp 75e76 ꢀC; IR (KBr, cmꢁ1) 2960, 1626,
1H), 5.60 (d, J¼5.0 Hz, 1H), 5.12 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz,
1456, 1241, 1014, 835, 692; 1H NMR (300 MHz, CDCl3)
d (ppm)
CDCl3)
d
(ppm) 151.9, 149.9, 137.5, 135.2, 134.8, 132.0, 129.5, 128.6,
7.54e7.51 (m, 2H), 7.38e7.35 (m, 4H), 7.19e7.06 (m, 6H), 6.86 (d,
J¼7.3 Hz, 1H), 5.61 (d, J¼5.0 Hz, 1H), 5.12 (d, J¼5.0 Hz, 1H), 1.25 (s,
128.5,128.4,126.0,124.0,119.7,116.4, 97.5, 45.7; HRMS-EI: m/z calcd
for C21H14Cl2OS: 384.0142, found: 384.0146.
9H); 13C NMR (75 MHz, CDCl3)
d (ppm) 152.0, 151.8, 150.5, 135.7,
133.9, 129.6, 128.7, 128.2, 128.1, 125.4, 124.8, 123.6, 120.5, 116.3, 97.5,
4.3.4. 4-(4-Chlorophenylthio)-2-(4-fluorophenyl)-4H-chromene
(6d). Mp 85e87 ꢀC; IR (KBr, cmꢁ1) 2358,1651, 1224,1005, 812, 655;
45.7, 34.5, 31.2; HRMS-CI: m/z [MþH]þ, calcd for C15H11OþC12H14
N2OS, 207.0810þ234.0827, found: 207.0817þ234.0843.
-
1H NMR (300 MHz, CDCl3)
d (ppm) 7.55e7.50 (m, 2H), 7.38 (d,
J¼8.8 Hz, 1H), 7.24e6.98 (m, 8H), 6.86 (d, J¼8.1 Hz, 1H), 5.54 (d,
4.3.11. 2-(2-Chlorophenyl)-5-(2-phenyl-4H-chromen-4-yl-thio)-
J¼5.0 Hz, 1H), 5.11 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
1,3,4-oxadiazole (6l). Mp 179e181 ꢀC; IR (KBr, cmꢁ1) 1634, 1486,
d
(ppm) 163.1 (d, 1JCeF¼247.1 Hz), 152.0, 150.1, 137.4, 135.1, 129.7 (d,
1243, 1031, 752, 684; 1H NMR (300 MHz, CDCl3)
d (ppm) 7.79e7.75
3
4JCeF¼3.3 Hz), 129.6, 129.5, 128.4, 126.6 (d, JCeF¼8.3 Hz), 123.9,
(m, 3H), 7.52 (d, J¼7.8Hz, 1H), 7.42e7.24 (m, 8H), 7.15 (t, J¼7.5 Hz,
2
5
119.8, 116.4, 115.3 (d, JCeF¼21.7 Hz), 96.8 (d, JCeF¼1.6 Hz), 45.8;
HRMS-EI: m/z calcd for C21H14ClFOS: 368.0438, found: 368.0450.
1H), 6.93 (d, J¼4.8 Hz, 1H), 5.73 (d, J¼4.8 Hz, 1H); 13C NMR (75 MHz,
CDCl3)
d (ppm) 175.4, 157.5, 153.4, 151.8, 133.2, 132.7, 131.3, 130.5,
130.0, 129.6, 128.8, 128.5, 126.9, 125.4, 124.3, 121.5, 117.2, 116.7, 92.8,
53.2; HRMS-CI: m/z [MþH]þ, calcd for C15H11OþC8H5N2OSCl,
207.0810þ211.9811, found: 207.0811þ211.9808.
4.3.5. 4-(4-Chlorophenylthio)-2-(furan-2-yl)-4H-chromene
(6e). Yellow oil; IR (KBr, cmꢁ1) 2359, 1635, 1230, 1011, 815, 694; 1H
NMR (300 MHz, CDCl3)
d (ppm) 7.40e7.34 (m, 2H), 7.23e7.01 (m,
6H), 6.82 (d, J¼8.1 Hz, 1H), 6.50 (d, J¼3.4 Hz, 1H), 6.41 (dd,
4.3.12. 4-(Dodecylthio)-2-phenyl-4H-chromene (6m). Yellow oil; IR
J1¼3.4 Hz, J2¼1.8 Hz, 1H), 5.65 (d, J¼5.0 Hz, 1H), 5.09 (d, J¼5.0 Hz,
(KBr, cmꢁ1) 2924, 1642, 1458, 1231, 1062, 911, 689; 1H NMR
1H); 13C NMR (75 MHz, CDCl3)
d
(ppm) 151.6, 147.9, 143.6, 142.7,
(300 MHz, CDCl3)
d
(ppm) 7.75 (d, J¼8.1 Hz, 2H), 7.45e7.35 (m, 4H),
137.2, 135.0, 129.8, 129.6, 128.42, 128.39, 123.8, 119.9, 116.3, 111.3,
107.3, 95.9, 45.2; HRMS-EI: m/z calcd for C19H13ClO2S: 340.0325,
found: 340.0333.
7.22 (t, J¼8.1 Hz, 1H), 7.13e7.04 (m, 2H), 5.62 (d, J¼4.8 Hz, 1H), 4.83
(d, J¼4.8 Hz, 1H), 2.50e2.24 (m, 2H), 1.42e1.15 (m, 20H), 0.88 (t,
J¼6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d (ppm) 152.1, 150.2, 133.7,
129.7, 128.8, 128.4, 128.1, 124.7, 123.9, 120.9, 116.3, 98.1, 39.9, 31.9,
29.6, 29.5, 29.44, 29.39, 29.3, 29.1, 29.0, 27.9, 22.7,14.1; HRMS-EI: m/
z calcd for C27H36OS: 408.2487, found: 408.2490.
4.3.6. 4-(4-Chlorophenylthio)-2-(thiophen-2-yl)-4H-chromene
(6f). Yellow oil; IR (KBr, cmꢁ1) 2357, 1631, 1234, 1008, 817, 685; 1H
NMR (300 MHz, CDCl3)
d
(ppm) 7.36 (d, J¼8.8 Hz,1H), 7.28e7.24 (m,
2H), 7.20e7.00 (m, 7H), 6.85 (d, J¼8.1 Hz, 1H), 5.55 (d, J¼5.0 Hz, 1H),
4.3.13. 2-(4-tert-Butylphenyl)-5-(2-(4-methoxyphenyl)-4H-chro-
5.09 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d
(ppm) 151.8,
men-4-ylthio)-1,3,4-oxadiazole (6n). Mp 96e97 ꢀC; IR (KBr, cmꢁ1
)
146.7, 137.5, 137.1, 135.2, 129.5, 128.44, 128.42, 127.9, 125.5, 124.1,
123.9, 119.8, 116.4, 96.5, 45.7; HRMS-EI: m/z calcd for C19H13ClO2S:
356.0096, found: 356.0101.
2959, 2357, 1622, 1456, 1247, 1027, 829, 611; 1H NMR (300 MHz,
CDCl3) (ppm) 7.77e7.71 (m, 4H), 7.49e7.35 (m, 4H), 7.24 (d,
d
J¼8.1 Hz, 1H), 7.12 (t, J¼7.5 Hz, 1H), 6.97e6.92 (m, 3H), 5.60 (d,
J¼4.6 Hz, 1H), 3.85 (s, 3H), 1.29 (s, 9H); 13C NMR (75 MHz, CDCl3)
4.3.7. 6-Chloro-4-(4-chlorophenylthio)-2-phenyl-4H-chromene
d (ppm) 175.6, 160.7, 159.7, 156.0, 153.0, 151.7, 129.9, 128.8, 126.8,
(6h). Mp 105e106 ꢀC; IR (KBr, cmꢁ1) 1647, 1228, 1006, 876, 692; 1H
126.4, 125.9, 125.8, 124.2, 119.6, 117.1, 116.9, 113.9, 91.3, 55.4, 53.1,
35.1, 31.0; HRMS-CI: m/z [MþH]þ, calcd for C16H13O2þC12H14N2OS,
237.0916þ234.0827, found: 237.0918þ234.0836.
NMR (300 MHz, CDCl3)
d (ppm) 7.55e7.52 (m, 2H), 7.39e7.37 (m,
4H), 7.16e7.02 (m, 5H), 6.80 (d, J¼8.7 Hz, 1H), 5.61 (d, J¼5.0 Hz, 1H),
5.05 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d (ppm) 150.9,
150.6, 137.6, 135.4, 133.2, 129.1, 129.0, 128.54, 128.51, 128.43, 128.40,
4.3.14. 2-(2-Chlorophenyl)-5-(2-(4-methoxyphenyl)-4H-chromen-4-
124.7, 121.5, 117.9, 96.8, 45.5; HRMS-CI: m/z [MþH]þ, calcd for
ylthio)-1,3,4-oxadiazole (6o). Mp 167e168 ꢀC; IR (KBr, cmꢁ1) 1634,

2434
G.-D. Yin et al. / Tetrahedron 69 (2013) 2430e2435
1465, 1248, 1030, 828, 614; 1H NMR (300 MHz, CDCl3)
d
(ppm)
C
13H9O2þC12H14N2OS, 197.0603þ234.0827, found: 197.0609þ
7.78e7.70 (m, 3H), 7.52 (d, J¼7.8 Hz, 1H), 7.44e7.22 (m, 5H), 7.14 (t,
234.0841.
J¼7.5 Hz,1H), 6.96e6.90 (m, 3H), 5.62 (d, J¼4.6 Hz,1H); 3.84 (s, 3H);
13C NMR (75 MHz, CDCl3)
d
(ppm) 175.4, 160.7, 157.5, 153.3, 151.8,
4.3.20. 4-(Dodecylthio)-2-(furan-2-yl)-4H-chromene (6u). Yellow
133.2, 132.6, 131.3, 130.5, 130.0, 128.8, 126.9, 126.8, 125.8, 124.2,
121.6, 117.2, 116.8, 113.8, 91.2, 55.3, 53.4; HRMS-CI: m/z [MþH]þ,
calcd for C16H13O2þC8H5ClN2OS, 237.0916þ211.9811, found:
237.0918þ211.9815.
oil; IR (KBr, cmꢁ1) 2924, 2352, 1633, 1233, 1008, 893, 673; 1H NMR
(300 MHz, CDCl3)
d
(ppm) 7.43e7.41 (m, 2H), 7.18 (t, J¼7.5 Hz, 1H),
7.09 (t, J¼7.5 Hz, 1H), 7.00 (d, J¼8.1 Hz, 1H), 6.64 (d, J¼3.3 Hz, 1H),
6.46 (dd, J1¼3.3 Hz, J2¼1.8 Hz, 1H), 5.63 (d, J¼4.8 Hz, 1H), 4.80 (d,
J¼4.8 Hz, 1H), 2.54e2.26 (m, 2H), 1.40e1.16 (m, 20H), 0.88 (t,
J¼6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d (ppm) 151.6, 148.1, 143.2,
4.3.15. 2-(4-Chlorophenyl)-4-(3-fluorophenylthio)-4H-chromene
(6p). Yellow oil; IR (KBr, cmꢁ1) 3071, 2923, 1638, 1223, 1006, 874,
142.7, 129.8, 128.2, 124.0, 120.9, 116.2, 111.3, 107.1, 97.0, 39.1, 31.9,
29.6, 29.5, 29.39, 29.37, 29.3, 29.1, 29.0, 28.0, 22.7, 14.1; HRMS-ESI:
m/z [MþNa]þ calcd for C25H34O2SNa: 421.2172, found: 421.2176.
677; 1H NMR (300 MHz, CDCl3)
d (ppm) 7.50e7.48 (m, 2H),
7.40e7.35 (m, 3H), 7.32e7.04 (m, 3H), 6.97e6.78 (m, 4H), 5.61 (d,
J¼5.0 Hz, 1H), 5.17 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
1
4.3.21. 4-(3-Fluorophenylthio)-2-(thiophen-2-yl)-4H-chromene
d
(ppm) 162.0 (d, JCeF¼247.1 Hz), 151.9, 149.9, 134.7, 133.4 (d,
(6v). Yellow oil; IR (KBr, cmꢁ1) 2924, 2352, 1632, 1227, 1052, 870,
3JCeF¼7.7 Hz), 132.0, 131.4 (d, JCeF¼2.9 Hz), 129.5, 129.3 (d,
4
711; 1H NMR (300 MHz, CDCl3)
d
(ppm) 7.36 (dd, J1¼7.5 Hz,
3JCeF¼8.3 Hz), 128.6, 126.0, 124.0, 122.3 (d, JCeF¼21.2 Hz), 119.7,
2
2
J2¼1.8 Hz, 1H), 7.28e7.16 (m, 2H), 7.13e6.82 (m, 7H), 5.56 (d,
116.4, 115.6 (d, JCeF¼20.9 Hz), 97.5, 45.7; HRMS-EI: m/z calcd for
J¼5.0 Hz, 1H), 5.15 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
C21H14ClFOS: 368.0438, found: 368.0437.
1
d
(ppm) 162.0 (d, JCeF¼247.1 Hz), 151.7, 146.7, 137.1, 133.4 (d,
3JCeF¼7.6 Hz), 131.5 (d, 4JCeF¼3.0 Hz), 129.5,129.4 (d, 3JCeF¼7.6 Hz),
4.3.16. 2-(4-tert-Butylphenyl)-5-(2-(4-chlorophenyl)-4H-chromen-
2
128.5, 127.4, 125.6, 124.2, 124.0, 122.4 (d, JCeF¼21.2 Hz), 119.8,
4-ylthio)-1,3,4-oxadiazole (6q). Mp 84e85 ꢀC; IR (KBr, cmꢁ1) 2962,
116.4, 96.4, 45.7; HRMS-CI: m/z, calcd for C13H9OSþC6H4FS,
213.0374þ127.0018, found: 213.0393þ127.0008.
1626, 1492, 1242, 1011, 829, 629; 1H NMR (300 MHz, CDCl3)
d (ppm)
7.77e7.70 (m, 4H), 7.48 (d, J¼7.5 Hz, 1H), 7.42e7.35 (m, 5H), 7.24 (d,
J¼7.5 Hz, 1H), 7.14 (t, J¼7.5 Hz, 1H), 6.93 (d, J¼4.6 Hz, 1H), 5.70 (d,
4.3.22. 2-(4-tert-Butylphenyl)-5-(2-(thiophen-2-yl)-4H-chromen-4-
ylthio)-1,3,4-oxadiazole (6w). Mp 139e140 ꢀC; IR (KBr, cmꢁ1) 2962,
2352, 1661, 1620, 1245, 1022, 832, 710; 1H NMR (300 MHz, CDCl3)
J¼4.6 Hz, 1H), 1.29 (s, 9H); 13C NMR (75 MHz, CDCl3)
d (ppm) 175.7,
159.8, 156.1, 152.2, 151.5, 135.4, 131.7, 130.1, 128.8, 128.7, 126.6, 126.5,
125.9, 124.5, 119.5, 117.2, 116.7, 93.4, 52.8, 35.1, 31.0; HRMS-CI: m/z
[MþH]þ, calcd for C15H10ClOþC12H14N2OS, 241.0420þ234.0827,
found: 241.0430þ234.0829.
d
(ppm) 7.75 (d, J¼8.5 Hz, 2H), 7.49e7.34 (m, 6H), 7.25e7.07 (m, 3H),
6.90 (d, J¼4.7 Hz, 1H), 5.62 (d, J¼4.7 Hz, 1H), 1.29 (s, 9H); 13C NMR
(75 MHz, CDCl3) d (ppm) 175.7,159.7,156.0,151.2,147.6,145.8,143.3,
130.0, 128.9, 126.4, 125.9, 124.4, 119.5, 117.1, 117.0, 111.5, 108.6, 91.7,
4.3.17. 2-(4-Fluorophenyl)-4-(3-fluorophenylthio)-4H-chromene
(6r). Yellow oil; IR (KBr, cmꢁ1) 2915, 2351, 1634, 1228, 1010, 759,
52.3, 35.1, 31.0; HRMS-CI: m/z [MþH]þ, calcd for C13H9OSþC12H14
N2OS, 213.0374þ234.0827, found: 213.0372þ234.0834.
-
675; 1H NMR (300 MHz, CDCl3)
d (ppm) 7.56e7.51 (m, 2H), 7.38 (dd,
J1¼7.8 Hz, J2¼1.8 Hz,1H), 7.24e7.02 (m, 5H), 6.96e6.79 (m, 4H), 5.56
4.3.23. 6-Chloro-4-(dodecylthio)-2-phenyl-4H-chromene
(d, J¼5.0 Hz, 1H), 5.18 (d, J¼5.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
(6x). Yellow oil; IR (KBr, cmꢁ1) 2940, 1652, 1235, 1007, 877, 692; 1H
1
d
(ppm) 163.0 (d, 1JCeF¼247.1 Hz), 161.9 (d, JCeF¼247.1 Hz), 151.8,
NMR (300 MHz, CDCl3)
d (ppm) 7.72e7.68 (m, 2H), 7.43e7.39 (m,
3
4
150.0, 133.5 (d, JCeF¼7.7 Hz), 131.3 (d, JCeF¼2.9 Hz), 129.7 (d,
4H), 7.17 (dd, J1¼8.8 Hz, J2¼2.5 Hz, 1H), 7.00 (d, J¼8.8 Hz, 2H), 5.60 (d,
4JCeF¼3.2 Hz), 129.4, 129.2 (d, JCeF¼8.3 Hz), 128.5, 126.5 (d,
3
J¼4.8 Hz,1H), 4.77 (d, J¼4.8 Hz,1H), 2.47e2.24 (m, 2H),1.42e1.16 (m,
3JCeF¼8.2 Hz), 123.9, 122.2 (d, JCeF¼21.2 Hz), 119.7, 116.3, 115.4 (d,
2
20H), 0.88 (t, J¼6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d (ppm) 150.6,
2JCeF¼20.9 Hz), 115.3 (d, JCeF¼21.6 Hz), 96.7, 45.6; HRMS-CI: m/z
2
150.2, 133.3, 129.3, 129.0, 128.6, 128.4, 128.3, 124.7, 122.6, 117.7, 97.7,
39.5, 31.9, 29.6, 29.5, 29.4, 29.3, 29.1, 29.0, 27.9, 22.7, 14.1; HRMS-EI:
m/z calcd for C27H35ClOS: 442.2097, found: 442.2099.
[MþH]þ, calcd for C15H11FOþC6H4FS, 225.0716þ127.0018, found:
225.0708þ127.0017.
4.3.18. 4-(Dodecylthio)-2-(4-fluorophenyl)-4H-chromene
(6s). Yellow oil; IR (KBr, cmꢁ1) 2924, 1649, 1230, 1063, 811, 616; 1H
4.3.24. 3-(4-Chlorophenylthio)-3-(2-hydroxyphenyl)-1-
phenylpropan-1-one (6aa). Mp 127e128 ꢀC; IR (KBr, cmꢁ1) 3416,
2355, 1662, 1602, 1229, 1084, 975, 672; 1H NMR (300 MHz, CDCl3)
NMR (300 MHz, CDCl3)
d
(ppm) 7.72e7.67 (m, 2H), 7.43 (d, J¼7.8 Hz,
1H), 7.21 (d, J¼7.5 Hz, 1H), 7.13e7.02 (m, 4H), 5.55 (d, J¼4.8 Hz, 1H),
d
(ppm) 7.90 (d, J¼8.8 Hz, 2H), 7.58e7.54 (m,1H), 7.45e7.06 (m, 9H),
4.82 (d, J¼4.8 Hz, 1H), 2.51e2.24 (m, 2H), 1.42e1.15 (m, 20H), 0.88
6.90e6.82 (m, 2H), 5.20 (dd, J1¼9.3 Hz, J2¼4.5 Hz, 1H), 3.76 (dd,
(t, J¼6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d (ppm) 163.1 (d,
J1¼18.0 Hz, J2¼9.3 Hz, 1H), 3.62 (dd, J1¼18.0 Hz, J2¼4.5 Hz, 1H); 13
C
1JCeF¼246.9 Hz), 151.9, 149.4, 129.8 (d, JCeF¼3.2 Hz), 129.7, 128.2,
126.6 (d, 3JCeF¼8.2 Hz), 124.0, 120.8, 116.2, 115.3 (d, 2JCeF¼21.6 Hz),
97.9 (d, 5JCeF¼1.6 Hz), 39.8, 31.9, 29.6, 29.5, 29.44, 29.40, 29.3, 29.1,
29.0, 28.0, 22.7, 14.1; HRMS-ESI: m/z [MþNa]þ calcd for
C27H35FOSNa: 449.2285, found: 449.2288.
4
NMR (75 MHz, CDCl3) d (ppm) 198.7,153.8,135.8,133.9,133.5,132.8,
132.4, 129.1, 128.9, 128.7, 128.4, 128.3, 127.5, 121.4, 118.1, 45.0, 41.8;
1H NMR (300 MHz, DMSO-d6)
d
(ppm) 9.75 (s, 1H), 7.96 (d, J¼7.5 Hz,
2H), 7.62 (t, J¼7.5 Hz, 1H), 7.49e7.46 (m, 2H), 7.34e7.26 (m, 5H),
7.06e7.00 (m, 1H), 6.80 (d, J¼7.7 Hz, 1H), 6.71 (d, J¼7.5 Hz, 1H), 5.29
(d, J¼7.2 Hz, 1H), 3.78e3.59 (m, 2H); 13C NMR (75 MHz, DMSO-d6)
4.3.19. 2-(4-tert-Butylphenyl)-5-(2-(furan-2-yl)-4H-chromen-4-
ylthio)-1,3,4-oxadiazole (6t). Mp 75e76 ꢀC; IR (KBr, cmꢁ1) 2960,
2354, 1624, 1491, 1244, 1007, 831, 685; 1H NMR (300 MHz, CDCl3)
d
(ppm) 197.1, 154.5, 136.4, 134.4, 133.3, 132.2, 131.4, 128.8, 128.7,
128.2, 128.0, 126.9, 119.0, 115.2, 43.3, 41.4; HRMS-ESI: m/z [MþNa]þ
calcd for C21H17ClO2SNa: 391.0530, found: 391.0537.
d
(ppm) 7.76 (d, J¼8.4 Hz, 2H), 7.49e7.33 (m, 5H), 7.20 (d, J¼8.0 Hz,1H),
7.12 (t, J¼7.5 Hz, 1H), 6.91 (d, J¼4.7 Hz,1H), 6.81 (d, J¼3.4 Hz, 1H), 6.50
(dd, J1¼3.4 Hz, J2¼1.8 Hz, 1H), 5.72 (d, J¼4.7 Hz, 1H), 1.29 (s, 9H); 13
C
Acknowledgements
NMR (75 MHz, CDCl3)
d (ppm) 175.7, 159.7, 156.0, 151.2, 147.6, 145.8,
143.3, 130.0, 128.9, 126.4, 125.9, 124.4, 119.5, 117.1, 117.0, 111.5, 108.6,
We gratefully acknowledge support from the National Natural
Science Foundation of China (Grant 21102042) and the Science and
91.7, 52.3, 35.1, 31.0; HRMS-CI: m/z [MþH]þ, calcd for

G.-D. Yin et al. / Tetrahedron 69 (2013) 2430e2435
2435
9453e9456; (d) Liu, Y.-K.; Qian, J.-Q.; Lou, S.-J.; Zhu, J.; Xu, Z.-Y. J. Org. Chem.
2010, 75, 1309e1312; (e) Malakar, C. C.; Schmidt, D.; Conrad, J.; Beifuss, U. Org.
Lett. 2011, 13, 1972e1975.
Technology Foundation for Creative Research Group of HBDE
(2013).
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Supplementary data
1H NMR and 13C NMR spectra for all new compounds. Supple-
mentary data associated with this article can be found in the online
version, at http://dx.doi.org/10.1016/j.tet.2013.01.047. These data
include MOL files and InChiKeys of the most important compounds
described in this article.
10. Gupta, A. K.; Kumari, K.; Singh, N.; Raghuvanshi, D. S.; Singh, K. N. Tetrahedron
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References and notes
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15. Crystal data for 6d: CCDC number 898680, C21H14ClFOS, triclinic, space group
ꢁ
ꢀ
Pꢁ1, a¼6.317(3), b¼10.243(4), c¼13.759(6) A,
a
¼85.000(5)ꢀ,
b
¼88.210(5)ꢀ,
Rasolofonjatovo, E.; Treguier, B.; Provot, O.; Hamze, A.; Brion, J. D.; Alami, M.
3
ꢁ
g
¼79.592(5)ꢀ, U¼872.2(6) A , Z¼2, specimen: 0.21ꢂ0.20ꢂ0.16 mm3,
Eur. J. Org. Chem. 2012, 1603e1615; (j) Majumdar, N.; Korthals, K. A.; Wulff, W.
D. J. Am. Chem. Soc. 2012, 134, 1357e1362.
T¼296(2) K, absorption coefficient 0.354 mmꢁ1, reflections collected 4994,
independent reflections 3051 [R(int)¼0.0158], refinement by full-matrix least-
squares on F2, data/restraints/parameters 3051/0/226, goodness-of-fit on F2¼1.
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Commun. 2012, 3712e3714.
019, final R indices [I>2s(I)] R1¼0.0396, wR2¼0.0866, R indices (all data) R1¼0.
ꢁꢁ3
0641, wR2¼0.0985, largest diff. peak and hole 0.177 and ꢁ0.204 e A
.
16. (a) Khatik, G. L.; Kumar, R.; Chakraborti, A. K. Org. Lett. 2006, 8, 2433e2436; (b)
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ꢀ
ꢀ~
kishin, G. I. Adv. Synth. Catal. 2008, 350, 591e601; (c) Aleman, J.; Nunez, A.;
Marzo, L.; Marcos, V.; Alvarado, C.; García Ruano, J. L. Chem.dEur. J. 2010, 16,