One-pot synthesis of sulfonyl (E)-stilbenes by nitrobenzene-mediated dimerizative desulfonation of benzylic sulfones

Article abstract of DOI:10.1016/j.tet.2014.01.045

A facile one-pot synthetic route for preparing sulfonyl (E)-stilbenes 4 is developed. The efficient route is realized by a nitrobenzene (PhNO ₂)-mediated dimerizative desulfonation of benzylic sulfones 3 in the presence of sodium hydride (NaH) in good yields. Some synthetic investigations of sulfonyl stilbenes 4 are also examined.

Full text of DOI:10.1016/j.tet.2014.01.045

Tetrahedron 70 (2014) 1740e1747
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
One-pot synthesis of sulfonyl (E)-stilbenes by nitrobenzene-
mediated dimerizative desulfonation of benzylic sulfones
*
Meng-Yang Chang , Yi-Chia Chen, Shin-Ying Lin, Chieh-Kai Chan
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan
a r t i c l e i n f o
a b s t r a c t
Article history:
A facile one-pot synthetic route for preparing sulfonyl (E)-stilbenes 4 is developed. The efficient route is
realized by a nitrobenzene (PhNO2)-mediated dimerizative desulfonation of benzylic sulfones 3 in the
presence of sodium hydride (NaH) in good yields. Some synthetic investigations of sulfonyl stilbenes 4
are also examined.
Received 29 October 2013
Received in revised form 14 January 2014
Accepted 20 January 2014
Available online 27 January 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Sulfonyl stilbenes
Dimerizative desulfonation
Benzylic sulfones
1. Introduction
cyclopropanes 2C using one-pot domino base-mediated annulation
strategy (see Scheme 1),13 one-pot base-mediated dimerizative
The stilbene skeleton is a central pharmacophore for the con-
struction of multi-functionalized structures possessing diversified
potential biological activities1 including anticancer,2 antifungal,3
antioxidant,4 and anti-inflammatory;5 it has also been applied to
photo-responsive OLEDs or NLO materials6 and photo-chemical or
photo-physical cisetrans isomerization7 in different technological
fields. Accordingly, the well-designed synthetic pathway is an im-
portant tool to establish a stilbene skeleton. Some classical methods
have adapted Perkin aldol-type condensation,8 Wittig or Hor-
nereWadswortheEmmons (HWE) olefination9 and transition
metal-mediated cross-couplings (for Pd: Heck, NegishieStille,
SuzukieMiyaura; for Ru, Grubbs metathesis; for Ti: McMurry).10
Because the synthetic approaches for domino types are currently
in vogue, many reagents mediated one-pot oxidative, reductive or
eliminative dimerizations have been developed.11 Many known
drugs include the core structure of stilbene. Their biological activ-
ities and chemical properties have emerged as key targets due to the
sulfonyl group being used as the main constituent of selective COX-
2 inhibitors, such as DuP-697, HMN-214, rofecoxib, and etoricoxib.12
desulfonation of benzylic sulfones 3 (the removal of olefinic motif)
with PhNO2 was examined. To explore the feasible trans-
formation,14,15 benzyl phenyl sulfone 3a and different functional-
ized nitrobenzenes were chosen as the starting substrate under
various basic conditions, as shown in Table 1.
O
MeO
Ph
O
S
O
t-BuOK
MeO
Ph
Tol
1
Ph
CHO
Ph
NaH
O
O
MeO
2C
O
MeO
conjugated addition/
ring-closure (ref 13c)
NaH
CHO
Me
O
Tol
S
Ph
MeO
O
Ph
MeO
O
O
2B
O
S
aldol condensation/
electrocyclization/
Tol
O
2A
oxidative dehydrogenation (ref 13b)
2. Results and discussion
condensation/olefin migration/
electrocyclization (ref 13a)
In continuation of our recent investigation into the skeleton of
Scheme 1. Application of cinnamyl sulfones 1.
cinnamyl sulfone (styrylmethyl sulfone) 1 for preparing tetrahy-
First, when NaH-mediated treatment of benzyl phenyl sulfone
3a with 4-fluoronitrobenzene was screened in refluxing THF, 4a
with (E)-configuration was afforded in 78% yield. The 1H NMR
drocyclobuta[a]naphthalenes
2A,
p-terphenyls
2B,
and
* Corresponding author. Tel.: þ886
7 3121101x2220; e-mail addresses: my-
chang@kmu.edu.tw, mychang624@yahoo.com.tw (M.-Y. Chang).
spectrum of 4a exhibited one singlet at
d 7.97 for the proton of the
0040-4020/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2014.01.045

M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
1741
Table 2
One-pot synthesis of sulfonyl (E)-stilbenes 4a,b
Table 1
Reaction conditions of 3aa
R
R
1
1
O
NaH, PhNO
2
O
4-NO Ph
2
Ph
Ph
R
1
S
O
2
O
S
R
O
base, additives
refluxing THF
2
refluxing THF
R
2
O
Ph
S
O
Ph
S
O
2
Tol
S
Tol
O
3
(E)-4
Tol
S Ar product
O
N
3a
(E)-4a
(no detected)
Entry
3 (R1, R2)
4, yield (%)
1
2
3
4
5
6
7
8
3a, Ph, Tol
3b, 2-FPh, Tol
3c, 3-MeOPh, Tol
3d, 4-MeOPh, Tol
3e, 4-ClPh, Tol
3f, 4-FPh, Tol
3g, Ph, Me
3h, Ph, n-Bu
3i, 3,4-CH2O2Ph, Tol
3j, 3,5-(MeO)2Ph, Tol
3k, 4-PhPh, Tol
3l, 1-Naphthalene, Tol
3m, 2-Naphthalene, Tol
3n, 1-Thiophene, Tol
3o, 3-Pyridine, Tol
3p, Ph, Ph
4a, 86
4b, 70
4c, 70
4d, 72
4e, 70
4f, 73
4g, 85
4h, 80
4i, 72
4j, 70
4k, 78
4l, 81
4m, 78
4n, 62
4o, 57
4p, 82
4q, 88
4r, 83
4s, 80
4t, 86
4u, 82
4v, 80
4w, 82
4x, 62
4y, 60
dc
Entry
Additives (equiv), base (equiv), time (h)
4a, yieldb (%)
1
2
3
4
5
6
7
8
4-F-1-NO2Ph (1), NaH (5), 3
4-F-1-NO2Ph (1), DMAP (5), 3
4-F-1-NO2Ph (1), t-BuOK (5), 3
4-F-1-NO2Ph (1), DBU (5), 3
2-F-1-NO2Ph (1), DBU (5), 3
2,4-Cl2-1-NO2Ph (1), NaH (5), 3
PhNO2 (1), NaH (5), 3
PhNO2 (2), NaH (5), 3
PhNO2 (1), NaH (10), 3
PhNO2 (1), NaH (5), 10
PhNO2 (0.5), NaH (5), 10
PhNO2 (0), NaH (10), 10
MeNO2 (1), NaH (5), 3
EtNO2 (1), NaH (5), 3
PhNO2 (0.5), NaH (5), 10
TEMPO (1), NaH (5), 3
78
60c
34d
55e
60f
70g
82
9
86
82
86
80
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
9
10
11
12
13
14
15
16
17
dh
dh
dh
76i
dj
80
3q, Ph, 4-MeOPh
3r, Ph, 4-FPh
3s, Ph, 3-MePh
PhNO2 (2), TEMPO (1), NaH (5), 3
a
3t, Ph, 4-EtPh
The reactions were run on a 2.0 mmol scale with 3a in refluxing THF (10 mL).
The product was >95% pure as determined by 1H NMR analysis.
Compound 3a of 18% was recovered.
Compound 3a of 28% was obtained.
Compound 3a of 26% was recovered.
Compound 3a of 25% was recovered.
Unknown mixture of 16% was isolated.
No reaction and 3a was recovered.
The reaction was treated with N2 system.
b
c
d
e
f
3u, Ph, 4-i-PrPh
3v, Ph, 4-n-BuPh
3w, Ph, 4-t-BuPh
3x, (E)-CH]CHPh, Tol
3y, (E)-CH]CH-4-MeOPh, Tol
3z, t-BuCH2, Tol
3aa, n-C8H17, Tol
3ab, n-C12H25, Tol
3ac, 2,6-F2Ph, Tol
3ad, 9-Anthracene, Tol
3ae, 4-NO2Ph, Tol
g
h
i
dc
dc
dd
j
Compound of 3a of 68% was recovered and 21% of unknown mixture was
dd
isolated.
de
a
The one-pot reaction was run on a 2.0 mmol scale with starting materials 3aey
and PhNO2 (4.0 mmol) in THF(10 mL).
b
-vinylic position. The structure of 4a was determined by single-
b
The isolated products 4aey was >95% pure as determined by 1H NMR analysis.
crystal X-ray crystallography.16 The resulting adduct replaced the
expected SNAr product. Experimental results are different from the
literature reports.17,18 Based on the results, various bases and ad-
ditives of PhNO2 derivatives were screened. Changing the base to
NaH, t-BuOK or DBU in boiling THF solution for the one-pot re-
action, we found that NaH was the optimal base to increase the
yield of 4a without the recovery of the starting material 3a (entries
1e4). Next, when PhNO2 was chosen as the promoter in the pres-
ence of NaH, the combination of NaH/PhNO2 provided a better yield
(entries 7e11). Interestingly, no reaction occurred even with
a 5 equiv of NaH in the absence of PhNO2 (entry 12). By changing
from PhNO2 to MeNO2 or EtNO2, no 4a was observed under the
same conditions (entries 13 and 14). Without the involvement of
air, 4a was still isolated in 76% yield in the presence of PhNO2 (entry
15). It showed that the reaction procedure does not need oxygen
(from air) as the oxidants. Furthermore, when PhNO2 was changed
to TEMPO (entry 16), 3a was recovered (68%). To combine PhNO2
and TEMPO (entry 17), 4a was isolated in 80% yield. The reaction
may not undergo a radical process. According to the above phe-
nomenon, we envisioned that PhNO2 is a key factor controlling high
(E)-selectivity of 4a during the dimerizative desulfonation.
c
No reaction and 3z, 3aa or 3ab was recovered.
Trace unknown mixture was obtained and major 3ac or 3ad was recovered.
Unknown mixture was obtained.
d
e
were also shown in the 2,6-difluorophenyl or 9-anthracenyl group
(entries 29e30). These experimental results clearly show that the
R1 group of skeleton 3 must be an aromatic group with less steric
hindrance due to (1) the benzylic
sulfone 3 being more easily deprotonated than the aliphatic group
(for 3aa or 3ab) by NaH and (2) the resulting delocalized -carb-
anion with a bulky group (for 3ac or 3ad) being a stable nucleophile
during the reversible equilibrium process. For 4-nitrobenzyl sul-
fone 3ae, an unknown mixture was yielded (entry 31).
For the possible reaction mechanism, carbanion A was first
proposed via NaH-mediated deprotonation of 3a (see Scheme 2).
After the representative SNAr process of A and PhNO2, self-
dimerative cross-couplings of B1 and B2 were initiated. Sub-
sequently, new single bond of C1 was formed via the removal of
PhNO2 and the dianion species. To achieve E2 process with stable
conformation, the single bond of C1 was rotated. By the trans-
configuration between proton and TolSO2 group, deprotonation of
C2 with NaH or dianion of PhNO2 provided sole (E)-4a and Tol-
SO2Na. After work-up, the anion species of PhNO2 could convert to
PhNO2 or other analogues.
Under the same conditions, trimer 5 was observed by the
treatment of 4af with PhNO2 via intermediates D and E (see Scheme
3).16 Therefore, benzylic sulfone played a key role to initiate the
formation of (E)-stilbene 4. To extend this one-pot domino protocol
for the cross-coupling, 3e and 3k were chosen as two starting
materials (Scheme 4). Four sulfonyl stilbenes 4e, 4k, 4z, and 4aa
a-position on the skeleton of
a
As shown in Table 2, some compounds 4aey were efficiently
constructed in good yields (57e88%) by the above one-pot cascade
reaction of compounds 3aey (entries 1e25). Different substituents
(R1 and R2), with diversified electron-withdrawing groups or
electron-donating groups, were well-performed. Compounds 4a,b,
4def, and 4l were determined by single-crystal X-ray crystallog-
raphy.16 But, when the R1 group was a neopentyl, n-octyl or n-
dodecyl aliphatic substituent, the starting material 3z, 3aa or 3ab
was recovered as a major product (entries 26e28). Similar results

1742
M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
TolSO Na
Tol
O S O
2
Ph
Ph
hv, I , EtOAc
2
(E)-4a
O
O
O
S
O
O
O
2
H
Ph
S
photolytic
ring-closure
S
S
Ph
S
Ph
O
R
R
2
Tol
2
Tol
Tol
O
O
O
C2
H
3a
NaH
NO
+
NO
2
2
bond
4a, 4p
6a, R = Tol (72%)
2
2
NaH
6b, R = Ph (70%)
rotation
R
1
t-BuOK, THF
elimination
NO
2
H
O
O
O
R
1
R
1
2
Tol
O
S
O
R
1
S
O
Ph
S
Ph
S
R
2
Tol
O
A
Ph
O
7a, X = H (75%)
Tol
Tol
O N
7b, X = 4-MeOPh (66%)
7c, X = 4-ClPh (70%)
2
Tol
or
O
S
O
B2
O
S
O
B1
C1
H
4a, 4d-e
O
S
O
O
Ph
Ph
Ph
Ph
S
O
Scheme 5. Reactions of skeleton 4.
Tol
2
Tol
NO
B2
B1
X
O
NaH, PhNO
2
NO
2
N.R.
Ph
S
2
Tol
refluxing THF
O
Scheme 2. Possible mechanism.
8a, X = Me
8b, X = Ph
Scheme 6. Reaction of skeleton 8 with PhNO2.
O
N
NaH, PhNO
N
N
2
S
Tol
O
3
N
After the examination for the proposed mechanism, we found
that the formation of intermediates B1/B2 and C1/C2 should be the
reasonable intermediates in the formation of skeleton 4 by PhNO2-
mediated dimerizative desulfonation of skeleton 3. There are three
points to support the possible mechanism: (1) only (E)-con-
figurated 4a is generated via the E2 process, (2) four sulfonyl (E)-
stilbenes 4e, 4k, 4z, 4aa with the similar distribution of yields are
observed by the intermolecular cross-couplings of intermediates
B1 and B2 (in situ from 3e and 3k), and (3) no 4a is isolated by only
addition of TEMPO via a radical process.
refluxing THF
- 3 TolSO Na
2
4af
5 (60%)
O
S
O
Tol
H
N
N
N
N
N
O
N
O
S
Tol
S
Tol
E
O
O
D
Scheme 3. Reaction of compound 4af with PhNO2.
3. Conclusion
In summary, we have successfully described the one-pot PhNO2-
mediated E-selective dimerizative desulfonation of benzylic sul-
fones 3 in the presence of NaH under boiling THF conditions. The
structures of the key products 4 were confirmed by X-ray crystal
analysis. This method represents good reactivity and tolerates an
array of functionality. Two products, 6a,b and 7aec, were obtained
by photo-induced annulation or base-promoted dehydrosulfona-
tion of skeleton 4. The one-pot facile synthetic route begins with
simple starting materials and reagents, and provides a potential
methodology for synthetic research.
Cl
Ph
O
O
S
S
O
Tol
Tol
S
O
O
Tol
Ph
Cl
Cl
O
Cl
4z (22%)
4aa (21%)
NaH
3e
+
Ph
PhNO
O
2
S
Tol
O
Ph
O
S
O
S
3k
Tol
Tol
4. Experimental section
4.1. General
O
O
Cl
Ph
4e (25%)
4k (20%)
Scheme 4. Cross-coupling of compounds 3e and 3k.
All other reagents and solvents were obtained from commercial
sources and used without further purification. Reactions were
routinely carried out under an atmosphere of dry air with magnetic
stirring. Products in organic solvents were dried with anhydrous
MgSO4 before concentration in vacuo. Melting points were de-
termined with an SMP3 melting apparatus. 1H and 13C NMR spectra
were recorded on a Varian INOVA-400 spectrometer operating at
were isolated in similar yields. From the observation of cross
dimerizative desulfonation, we believe that PhNO2 is the key factor
affecting intermolecular aryl group exchanges. For exploring the
synthetic application of skeleton 4, photolytic ring-closure or re-
ductive elimination was studied (Scheme 5). Two useful skeletons,
sulfonyl phenanthrenes 6a,b and diaryl alkynes 7aec, gave modest
yields via photo-induced annulation19 or base-promoted dehy-
drosulfonation. A two-step novel access to prepare 6 and 7 was
described from skeleton 4. The structures of 6a and 7c were de-
termined by single-crystal X-ray crystallography.16 By the above
protocol, 8 (X¼Me or Ph) was treated with PhNO2,15g no reaction
was observed (Scheme 6).
400 and at 100 MHz, respectively. Chemical shifts (d) are reported
in parts per million (ppm) and the coupling constants (J) are given
in hertz (Hz). High resolution mass spectra (HRMS) were measured
with a mass spectrometer Finnigan/Thermo Quest MAT 95XL. X-ray
crystal structures were obtained with an Enraf-Nonius FR-590
diffractometer (CAD4, Kappa CCD). Elemental analyses were carried

M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
1743
out with Heraeus Vario III-NCSH, Heraeus CHN-OS-Rapid Analyzer
or Elementar Vario EL III.
CDCl3): d 159.69, 159.14, 144.06, 141.33, 137.05, 135.60, 133.86,
132.56, 129.76, 129.35, 129.27 (2ꢁ), 128.60 (2ꢁ), 123.57, 122.98,
116.78, 115.38, 115.30, 114.10, 55.12, 54.71, 21.47. Anal. Calcd for
4.2. A representative synthetic procedure of compounds
C23H22O4S: C, 70.03; H, 5.62. Found: C, 70.30; H, 5.86.
4aeaa and 5
4.2.4. Compound (4d).15f Yield¼72% (284 mg); colorless solid;
mp¼125e126 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3055, 2948, 1602, 1377, 1141, 901; HRMS (ESI, Mþþ1) calcd
for C23H23O4S 395.1317, found 395.1320; 1H NMR (400 MHz, CDCl3):
A representative synthetic procedure of compounds 4aeaa and
5 is as follows: sodium hydride (NaH, 60% in oil, 400 mg,10.0 mmol)
was added to a stirred solution of skeleton 3 (2.0 mmol) in THF
(8 mL) at 0 ꢀC. The resulting solution was stirred at 0 ꢀC for 5 min
and warmed to rt for 5 min. A solution of nitrobenzene (490 mg,
4.0 mmol) in THF (2 mL) was slowly added to the reaction mixture
at rt for 1 min. The reaction mixture was stirred at reflux for 3 h and
cooled to rt. Water (1 mL) was added to the reaction mixture at 0 ꢀC.
The solvent was concentrated under reduced pressure. The
resulting residue was diluted with water (10 mL) and the product
mixture was extracted with CH2Cl2 (3ꢁ20 mL). The combined or-
ganic layers were washed with brine, dried, filtered, and evapo-
rated to afford crude product. Purification on silica gel (hexanes/
EtOAc¼15:1 to 4:1) afforded compounds 4aeaa and 5.
d
7.86 (s, 1H), 7.50 (d, J¼8.4 Hz, 2H), 7.18 (d, J¼8.4 Hz, 2H), 7.04 (d,
J¼9.2 Hz, 2H), 6.95 (d, J¼8.8 Hz, 2H), 6.82 (d, J¼8.8 Hz, 2H), 6.70 (d,
J¼9.2 Hz, 2H), 3.82 (s, 3H), 3.75 (s, 3H), 2.38 (s, 3H); 13C NMR
(100 MHz, CDCl3):
d 160.89, 160.07, 143.71, 138.49, 137.04, 136.27,
132.22 (2ꢁ), 132.19 (2ꢁ), 129.26 (2ꢁ), 128.48 (2ꢁ), 125.64, 123.51,
114.36 (2ꢁ), 113.92 (2ꢁ), 55.23, 55.19, 21.55. Anal. Calcd for
C23H22O4S: C, 70.03; H, 5.62. Found: C, 70.25; H, 5.81. Single-crystal
X-ray diagram: crystal of 4d was grown by slow diffusion of EtOAc
into a solution of 4d in CH2Cl2 to yield colorless prisms. The com-
pound crystallizes in the monoclinic crystal system, space group
ꢀ
ꢀ
ꢀ
P121/c1, a¼14.6251(10) A, b¼5.8398(4) A, c¼24.7403(17) A,
V¼2026.9(2) A , Z¼4, dcalcd¼1.293 g/cm3, F(000)¼832, 2
q
range
3
ꢀ
4.2.1. Compound (4a).20 Yield¼86% (287 mg); colorless solid;
mp¼173e175 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3014, 2935, 1602, 1418, 1321, 1148, 913; HRMS (ESI, Mþþ1)
calcd for C21H19O2S 335.1106, found 335.1112; 1H NMR (400 MHz,
1.72e26.38ꢀ, R indices (all data) R1¼0.0948, wR2¼0.2201.
4.2.5. Compound (4e). Yield¼70% (281 mg); colorless solid; mp
>250 ꢀC (recrystallized from hexanes and EtOAc); IR (CHCl3): 3051,
2955, 1607, 1362, 1142, 909; HRMS (ESI, Mþþ1) calcd for
CDCl3):
d
7.94 (s, 1H), 7.50 (d, J¼8.4 Hz, 2H), 7.38e7.12 (m, 8H),
7.07e7.02 (m, 4H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3):
C
21H17Cl2O2S 403.0326, found 403.0325; 1H NMR (400 MHz,
d
144.09, 141.52, 137.26, 135.73, 132.86, 131.37, 130.74 (2ꢁ), 130.50
CDCl3):
7.21 (d, J¼8.0 Hz, 2H), 7.17 (d, J¼8.4 Hz, 2H), 7.01e6.96 (m, 4H), 2.40
(s, 3H); 13C NMR (100 MHz, CDCl3):
144.47, 141.08, 136.38, 136.23,
d
7.90 (s, 1H), 7.49 (d, J¼8.4 Hz, 2H), 7.28 (d, J¼8.4 Hz, 2H),
(2ꢁ), 129.94, 129.33 (2ꢁ), 129.08, 128.80 (2ꢁ), 128.64 (2ꢁ), 128.45
(2ꢁ), 21.59. Anal. Calcd for C21H18O2S: C, 75.42; H, 5.42. Found: C,
75.63; H, 5.57. Single-crystal X-ray diagram: crystal of 4a was
grown by slow diffusion of EtOAc into a solution of 4a in CH2Cl2 to
yield colorless prisms. The compound crystallizes in the monoclinic
d
135.30, 132.00 (2ꢁ), 131.56 (2ꢁ), 131.03, 129.55 (2ꢁ), 129.31 (2ꢁ),
128.90 (2ꢁ), 128.60 (2ꢁ), 128.52, 128.31, 21.61. Anal. Calcd for
C21H16Cl2O2S: C, 62.54; H, 4.00. Found: C, 62.30; H, 4.29. Single-
ꢀ
crystal system, space group P121/n1, a¼12.3185(4) A,
crystal X-ray diagram: crystal of 4e was grown by slow diffusion
of EtOAc into a solution of 4e in CH2Cl2 to yield colorless prisms. The
compound crystallizes in the monoclinic crystal system, space
3
ꢀ
ꢀ
ꢀ
b¼5.8327(2) A, c¼24.3654(8) A, V¼1722.11(10) A , Z¼4,
dcalcd¼1.290 g/cm3, F(000)¼704, 2
q
range 1.70e26.36ꢀ, R indices
ꢀ
ꢀ
ꢀ
(all data) R1¼0.0738, wR2¼0.1668.
group P121/c1, a¼13.599(6) A, b¼5.740(3) A, c¼25.291(14) A,
V¼1902.3(17) A , Z¼4, dcalcd¼1.408 g/cm3, F(000)¼832, 2
q
range
3
ꢀ
4.2.2. Compound (4b). Yield¼70% (259 mg); colorless solid;
mp¼135e137 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3045, 2953, 1621, 1425, 1334, 1156, 921; HRMS (ESI, Mþþ1)
calcd for C21H17F2O2S 371.0917, found 371.0922; 1H NMR (400 MHz,
CDCl3):
7.28e7.15 (m, 4H), 7.05 (dt, J¼0.8, 10.0 Hz, 1H), 6.90e6.75 (m, 3H),
2.38 (s, 3H); 13C NMR (100 MHz, CDCl3):
161.29 (d, J¼252.3 Hz),
1.55e26.49ꢀ, R indices (all data) R1¼0.0898, wR2¼0.2142.
4.2.6. Compound (4f). Yield¼73% (270 mg); colorless solid;
mp¼226e228 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3044, 2958, 1618, 1426, 1338,1160, 922; HRMS (ESI, Mþþ1)
calcd for C21H17F2O2S 371.0917, found 371.0923; 1H NMR (400 MHz,
d
8.32 (s, 1H), 7.53 (d, J¼8.4 Hz, 2H), 7.39e7.33 (m, 2H),
d
CDCl3):
7.07e7.00 (m, 6H), 6.90e6.56 (m, 2H), 2.39 (s, 3H); 13C NMR
(100 MHz, CDCl3):
164.46 (d, J¼250.9 Hz), 163.23 (d, J¼247.9 Hz),
d
7.91 (s, 1H), 7.49 (d, J¼8.0 Hz, 2H), 7.20 (d, J¼8.0 Hz, 2H),
159.71 (d, J¼249.3 Hz), 144.37, 136.42, 136.81, 135.40, 132.69 (d,
J¼2.2 Hz), 131.93 (d, J¼9.1 Hz), 131.75 (d, J¼6.8 Hz), 131.63 (d,
J¼8.3 Hz), 129.42 (2ꢁ), 128.57 (2ꢁ), 124.42 (d, J¼3.8 Hz), 123.96 (d,
J¼3.8 Hz), 121.08 (d, J¼11.4 Hz), 118.77 (d, J¼15.9 Hz), 115.80 (d,
J¼21.9 Hz), 115.76 (d, J¼21.2 Hz), 21.61. Anal. Calcd for C21H16F2O2S:
C, 68.09; H, 4.35. Found: C, 68.40; H, 4.68. Single-crystal X-ray di-
agram: crystal of 4b was grown by slow diffusion of EtOAc into
a solution of 4b in CH2Cl2 to yield colorless prisms. The compound
crystallizes in the orthorhombic crystal system, space group Pca21,
d
144.33, 136.42, 132.71 (d, J¼8.3 Hz, 2ꢁ), 132.43 (d, J¼8.4 Hz, 2ꢁ),
128.87 (d, J¼3.0 Hz), 127.03 (d, J¼3.8 Hz), 123.53, 123.37, 129.47
(2ꢁ), 128.58 (2ꢁ), 116.23 (d, J¼21.2 Hz, 2ꢁ), 115.77 (d, J¼21.2 Hz,
2ꢁ), 21.60. Anal. Calcd for C21H16F2O2S: C, 68.09; H, 4.35. Found: C,
68.20; H, 4.13. Single-crystal X-ray diagram: crystal of 4f was grown
by slow diffusion of EtOAc into a solution of 4f in CH2Cl2 to yield
colorless prisms. The compound crystallizes in the monoclinic
3
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
a¼12.984(2) A, b¼8.6056(13) A, c¼15.989(3) A, V¼1786.5(5) A ,
crystal system, space group P121/n1, a¼12.3430(9) A,
Z¼4, dcalcd¼1.377 g/cm3, F(000)¼768, 2
q
range 2.55e26.39ꢀ, R in-
b¼5.7877(4) A, c¼25.3347(17) A, V¼1767.4(2) A , Z¼4,
3
ꢀ
ꢀ
ꢀ
dices (all data) R1¼0.0577, wR2¼0.1303.
dcalcd¼1.392 g/cm3, F(000)¼768, 2
q
range 1.65e26.50ꢀ, R indices
(all data) R1¼0.0765, wR2¼0.1066.
4.2.3. Compound (4c). Yield¼70% (276 mg); colorless solid;
mp¼73e75 ꢀC (recrystallized from hexanes and EtOAc); IR (CHCl3):
3034, 2953, 1611, 1388, 1139, 891; HRMS (ESI, Mþþ1) calcd for
4.2.7. Compound (4g). Yield¼85% (219 mg); colorless solid;
mp¼117e119 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3018, 2943, 1608, 1422, 1319, 1144, 917; HRMS (ESI, Mþþ1)
calcd for C15H15O2S 259.0793, found 259.0780; 1H NMR (400 MHz,
C
d
23H23O4S 395.1317, found 395.1322; 1H NMR (400 MHz, CDCl3):
7.89 (s, 1H), 7.54 (d, J¼8.4 Hz, 2H), 7.20 (d, J¼8.4 Hz, 2H), 7.17 (d,
J¼8.0 Hz,1H), 7.11 (d, J¼8.0 Hz,1H), 6.89 (ddd, J¼1.2, 2.4, 8.4 Hz,1H),
6.90 (ddd, J¼1.2, 2.4, 8.4 Hz, 1H), 6.78e6.76 (m, 1H), 6.59e6.56 (m,
3H), 3.65 (s, 3H), 3.47 (s, 3H), 2.37 (s, 3H); 13C NMR (100 MHz,
CDCl3):
7.20e7.16 (m, 2H), 7.09e7.07 (m, 2H), 2.79 (s, 3H); 13C NMR
(100 MHz, CDCl3):
140.30, 137.82, 132.40, 131.37, 130.47 (2ꢁ),
d 7.81 (s, 1H), 7.50e7.46 (m, 5H), 7.28e7.24 (m, 1H),
d

1744
M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
130.34 (2ꢁ), 129.98, 129.55, 129.37 (2ꢁ), 128.41 (2ꢁ), 39.78. Anal.
a solution of 4l in CH2Cl2 to yield colorless prisms. The compound
crystallizes in the monoclinic crystal system, space group P121/n1,
Calcd for C15H14O2S: C, 69.74; H, 5.46. Found: C, 69.98; H, 5.38.
3
ꢀ
ꢀ
ꢀ
ꢀ
a¼13.4592(15) A, b¼8.2686(9) A, c¼19.771(2) A, V¼2172.3(4) A ,
4.2.8. Compound (4h). Yield¼80% (240 mg); colorless gum; IR
(CHCl3): 3019, 2932, 1611, 1429, 1320, 1149, 918; HRMS (ESI, Mþþ1)
calcd for C18H21O2S 301.1262, found 301.1266; 1H NMR (400 MHz,
Z¼4, dcalcd¼1.329 g/cm3, F(000)¼912, 2
q
range 1.71e26.66ꢀ, R in-
dices (all data) R1¼0.1137, wR2¼0.2331.
CDCl3):
d
7.78 (s, 1H), 7.47e7.43 (m, 5H), 7.27e7.24 (m, 1H),
4.2.13. Compound (4m). Yield¼78% (339 mg); colorless solid;
mp¼212e214 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3023, 2937, 1617, 1422, 1330, 1149, 916; HRMS (ESI, Mþþ1)
calcd for C29H23O2S 435.1419, found 435.1422; 1H NMR (400 MHz,
7.20e7.16 (m, 2H), 7.09e7.07 (m, 2H), 2.84e2.80 (m, 2H), 1.79e1.71
(m, 2H), 1.42e1.32 (m, 2H), 0.88 (t, J¼7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3):
d
138.90, 138.85, 132.59, 131.46, 130.48 (2ꢁ),
130.27 (2ꢁ), 129.92, 129.49, 129.30 (2ꢁ), 128.40 (2ꢁ), 50.66, 24.18,
CDCl3):
d
8.23 (s, 1H), 7.86 (d, J¼8.0 Hz, 1H), 7.78e7.73 (m, 4H),
21.41, 13.43.
7.67e7.63 (m, 2H), 7.57e7.49 (m, 4H), 7.45e7.39 (m, 3H), 7.16 (d,
J¼8.0 Hz, 2H), 7.11 (dd, J¼1.6, 8.8 Hz,1H), 6.96 (dd, J¼1.6, 8.8 Hz,1H),
4.2.9. Compound (4i). Yield¼72% (304 mg); colorless solid;
mp¼195e197 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3049, 2952, 1610, 1360, 1148, 909; HRMS (ESI, Mþþ1) calcd
for C23H19O6S 423.0902, found 423.0912; 1H NMR (400 MHz,
2.36 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 144.05, 141.46, 137.69,
135.88, 133.63, 133.20, 132.84, 132.24, 130.64, 130.46, 129.36 (2ꢁ),
128.80, 128.59 (2ꢁ), 128.51 (2ꢁ), 128.40, 127.99, 127.97 (2ꢁ), 127.72,
127.48, 127.39, 126.95, 126.46, 126.34, 125.94, 21.52. Anal. Calcd for
CDCl3):
d
7.81 (s, 1H), 7.52 (d, J¼8.8 Hz, 2H), 7.20 (d, J¼8.4 Hz, 2H),
C29H22O2S: C, 80.15; H, 5.10. Found: C, 80.37; H, 5.23.
6.83 (dd, J¼1.6, 8.4 Hz, 1H), 6.72 (s, 1H), 6.70 (s, 1H), 6.57 (d,
J¼1.6 Hz,1H), 6.44 (d, J¼1.6 Hz,1H), 6.41 (dd, J¼1.6, 8.0 Hz,1H), 6.00
(s, 2H), 5.91 (s, 2H), 2.39 (s, 3H); 13C NMR (100 MHz, CDCl3):
4.2.14. Compound (4n). Yield¼62% (215 mg); brown viscous gum;
IR (CHCl3): 3034, 2942, 1617, 1433, 1342, 1161, 950; HRMS (ESI,
Mþþ1) calcd for C17H15O2S3 347.0234, found 347.0233; 1H NMR
d
149.23, 148.39, 148.05, 147.68, 143.96, 138.81, 137.33, 136.01,
129.36 (2ꢁ), 128.52 (2ꢁ), 127.23, 127.04, 124.80, 124.45, 111.00,
(400 MHz, CDCl3):
d
8.24 (s,1H), 7.58 (d, J¼8.4 Hz, 2H), 7.51 (dd, J¼1.2,
109.03, 108.85, 108.38, 101.42, 101.36, 21.60. Anal. Calcd for
4.8 Hz,1H), 7.33 (dt, J¼1.2, 5.2 Hz,1H), 7.30 (dt, J¼1.2, 5.2 Hz,1H), 7.23
(d, J¼8.4 Hz, 2H), 7.06 (dd, J¼3.2, 4.8 Hz, 1H), 7.00 (dd, J¼3.6, 4.8 Hz,
1H), 6.80 (dd, J¼1.2, 3.6 Hz, 1H), 2.40 (s, 3H); 13C NMR (100 MHz,
C
23H18O6S: C, 65.39; H, 4.29. Found: C, 65.58; H, 4.41.
4.2.10. Compound (4j). Yield¼70% (318 mg); colorless solid;
mp¼144e146 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3052, 2958, 1610, 1365, 1145, 910; HRMS (ESI, Mþþ1) calcd
for C25H27O6S 455.1528, found 455.1533; 1H NMR (400 MHz,
CDCl3): d 144.20, 136.31, 135.45, 134.87, 134.19, 131.95, 131.54, 131.35,
130.09, 129.57, 129.40 (2ꢁ), 128.55 (2ꢁ), 127.71, 126.98, 21.60.
4.2.15. Compound (4o). Yield¼57% (192 mg); colorless solid;
mp¼138e140 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3044, 2937, 1635, 1439, 1342, 1152, 941; HRMS (ESI, Mþþ1)
calcd for C19H17N2O2S 337.1011, found 337.1018; 1H NMR (400 MHz,
CDCl3):
d
7.81 (s, 1H), 7.56 (d, J¼8.0 Hz, 2H), 7.20 (d, J¼8.0 Hz, 2H),
6.42 (t, J¼2.0 Hz, 1H), 6.35 (t, J¼2.0 Hz, 1H), 6.31 (d, J¼2.0 Hz, 2H),
6.14 (d, J¼2.0 Hz, 2H), 3.60 (s, 6H), 3.52 (s, 6H), 2.37 (s, 3H); 13C NMR
(100 MHz, CDCl3):
d
160.81 (2ꢁ), 160.27 (2ꢁ), 144.07, 141.52, 137.04,
CDCl3):
d
8.60 (dd, J¼1.6, 5.2 Hz, 1H), 8.46 (dd, J¼1.6, 4.8 Hz, 1H), 8.41
135.58, 134.19, 133.08, 129.21 (2ꢁ), 128.66 (2ꢁ), 108.22 (2ꢁ), 108.06
(d, J¼2.0 Hz, 1H), 8.02 (s, 2H), 7.61 (dt, J¼2.0, 8.0 Hz, 1H), 7.47 (d,
J¼8.4 Hz, 2H), 7.32 (ddd, J¼0.8, 4.8, 8.0 Hz, 1H), 7.21e7.18 (m, 3H),
7.07 (dd, J¼4.8, 8.4 Hz, 1H), 2.37 (s, 3H); 13C NMR (100 MHz, CDCl3):
(2ꢁ), 102.99, 101.66, 55.23 (2ꢁ), 55.93 (2ꢁ), 21.42. Anal. Calcd for
C
25H26O6S: C, 66.06; H, 5.77. Found: C, 66.19; H, 6.02.
d
151.51, 150.80, 150.49, 150.44, 144.97, 140.88, 138.27, 136.22, 135.14,
4.2.11. Compound (4k). Yield¼78% (379 mg); colorless solid;
mp¼172e173 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3013, 2934, 1605, 1420, 1325, 1150, 913; HRMS (ESI, Mþþ1)
calcd for C33H27O2S 487.1732, found 487.1733; 1H NMR (400 MHz,
134.54, 129.74 (2ꢁ), 128.52 (2ꢁ), 128.35, 127.27, 123.67, 123.30, 21.57.
4.2.16. Compound (4p). Yield¼82% (262 mg); colorless solid;
mp¼176e178 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3015, 2938, 1606, 1418, 1322, 1149, 913; HRMS (ESI, Mþþ1)
calcd for C20H17O2S 321.0949, found 321.0952; 1H NMR (400 MHz,
CDCl3):
d
8.04 (s, 1H), 7.65 (d, J¼8.0 Hz, 2H), 7.59 (d, J¼8.0 Hz, 2H),
7.58 (d, J¼8.0 Hz, 2H), 7.54e7.32 (m, 9H), 7.22 (d, J¼8.4 Hz, 4H), 7.17
(d, J¼8.0 Hz, 2H), 2.40 (s, 3H); 13C NMR (100 MHz, CDCl3):
d
144.08,
CDCl3): d 7.98 (s, 1H), 7.64e7.62 (m, 2H), 7.55e7.51 (m, 1H), 7.40 (d,
142.59, 141.64, 141.03, 139.94, 139.77, 137.01, 135.83, 131.77, 131.15
(2ꢁ), 131.00 (2ꢁ), 130.36, 129.38 (2ꢁ), 128.84 (2ꢁ), 128.79 (2ꢁ),
128.61 (2ꢁ), 127.82, 127.76, 127.37 (2ꢁ), 127.03 (2ꢁ), 126.96 (2ꢁ),
126.89 (2ꢁ), 21.57. Anal. Calcd for C33H26O2S: C, 81.45; H, 5.39.
Found: C, 81.60; H, 5.37.
J¼8.0 Hz, 2H), 7.38e7.34 (m, 1H), 7.30e7.23 (m, 3H), 7.18e7.15 (m,
2H), 7.09e7.06 (m, 2H), 7.04e7.02 (m, 2H); 13C NMR (100 MHz,
CDCl3): d 141.28, 138.64, 137.57, 133.13, 132.72, 131.21, 130.70, 130.49
(2ꢁ), 130.02, 130.02, 129.13, 128.79 (2ꢁ), 128.64 (2ꢁ), 128.58 (2ꢁ),
128.44 (2ꢁ). Anal. Calcd for C20H16O2S: C, 74.97; H, 5.03. Found: C,
75.30; H, 5.27.
4.2.12. Compound (4l). Yield¼81% (352 mg); colorless solid;
mp¼211e213 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3022, 2937, 1617, 1424, 1330, 1149, 917; HRMS (ESI, Mþþ1)
calcd for C29H23O2S 435.1419, found 435.1422; 1H NMR (400 MHz,
4.2.17. Compound (4q). Yield¼88% (308 mg); colorless solid;
mp¼157e159 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3038, 2958, 1619, 1384, 1142, 902; HRMS (ESI, Mþþ1) calcd
for C21H19O3S 351.1055, found 351.1062; 1H NMR (400 MHz, CDCl3):
CDCl3):
d
9.04 (s, 1H), 8.32 (d, J¼8.4 Hz, 1H), 7.81 (d, J¼8.4 Hz, 1H),
7.78 (d, J¼8.0 Hz, 1H), 7.73 (d, J¼8.0 Hz, 1H), 7.66 (d, J¼8.0 Hz, 1H),
7.61 (d, J¼8.4 Hz, 1H), 7.55e7.52 (m, 2H), 7.50 (d, J¼8.4 Hz, 2H),
7.35e7.29 (m, 2H), 7.19 (d, J¼7.6 Hz, 1H), 7.13 (d, J¼7.6 Hz, 1H), 7.09
(d, J¼8.0 Hz, 2H), 6.95e6.87 (m, 2H), 2.32 (s, 3H); 13C NMR
d
7.93 (s, 1H), 7.53 (d, J¼9.2 Hz, 2H), 7.37e7.33 (m, 1H), 7.30e7.26 (m,
2H), 7.23e7.19 (m, 1H), 7.15e7.11 (m, 2H), 7.06e7.03 (m, 4H), 6.84 (d,
J¼9.2 Hz, 2H), 3.78 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 163.19,
141.63, 136.55, 132.65, 131.27, 130.55 (2ꢁ), 130.51 (2ꢁ), 130.24 (2ꢁ),
129.87, 129.72, 128.93, 128.62 (2ꢁ), 128.26 (2ꢁ), 113.76 (2ꢁ), 55.40.
Anal. Calcd for C21H18O3S: C, 71.98; H, 5.18. Found: C, 72.20; H, 5.33.
(100 MHz, CDCl3):
d 144.17, 141.80, 136.74, 135.38, 133.32, 133.29,
131.91, 131.86, 130.00, 129.92, 129.65, 129.34, 129.30 (2ꢁ), 128.87
(2ꢁ), 128.79, 128.33, 128.08, 126.98, 126.73, 126.42, 126.11, 125.88,
125.14, 124.92, 124.86, 123.35, 21.49. Anal. Calcd for C29H22O2S: C,
80.15; H, 5.10. Found: C, 80.29; H, 5.31. Single-crystal X-ray dia-
gram: crystal of 4l was grown by slow diffusion of EtOAc into
4.2.18. Compound (4r). Yield¼83% (281 mg); colorless solid;
mp¼162e164 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3034, 2959, 1620, 1431, 1325, 1150, 911; HRMS (ESI, Mþþ1)

M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
1745
calcd for C20H16FO2S 339.0855, found 339.0853; 1H NMR (400 MHz,
CDCl3): 7.97 (s,1H), 7.65e7.60 (m, 2H), 7.40e7.36 (m,1H), 7.33e7.22
(m, 3H), 7.17e7.14 (m, 2H), 7.09e7.02 (m, 6H); 13C NMR (100 MHz,
CDCl3):
132.48, 131.28 (d, J¼9.8 Hz, 2ꢁ), 130.99, 130.62 (2ꢁ), 130.44 (2ꢁ),
130.08, 129.21, 128.84 (2ꢁ), 128.41 (2ꢁ), 115.88 (d, J¼22.7 Hz, 2ꢁ).
Anal. Calcd for C20H15FO2S: C, 70.99; H, 4.47. Found: C, 71.18; H, 4.63.
Mþþ1) calcd for C25H23O2S 387.1419, found 387.1423; 1H NMR
d
(400 MHz, CDCl3):
d
7.80 (d, J¼8.0 Hz, 2H), 7.58 (d, J¼6.8 Hz, 1H),
7.50e7.28 (m, 12H), 7.16 (d, J¼6.8 Hz, 1H), 7.10 (d, J¼15.6 Hz, 1H),
d
165.34 (d, J¼254.7 Hz), 140.97, 137.56, 134.58 (d, J¼3.0 Hz),
7.06 (d, J¼16.4 Hz, 1H), 6.89 (d, J¼16.4 Hz, 1H), 2.40 (s, 3H); 13C NMR
(100 MHz, CDCl3): d 143.98, 142.78, 137.93, 137.52, 137.47, 137.11,
136.34, 135.88, 129.68 (2ꢁ), 129.44, 128.87 (2ꢁ), 128.73 (3ꢁ), 127.74
(2ꢁ), 127.42 (2ꢁ), 126.86 (2ꢁ), 122.18, 117.37, 21.53.
4.2.19. Compound (4s). Yield¼80% (267 mg); colorless solid;
mp¼130e132 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3013, 2935, 1602, 1416, 1320, 1148, 912; HRMS (ESI, Mþþ1)
calcd for C21H19O2S 335.1106, found 335.1110; 1H NMR (400 MHz,
4.2.25. Compound (4y). Yield¼60% (268 mg); yellowish viscous
gum; IR (CHCl3): 3586, 2942,1602, 1401, 1312,1147, 928; HRMS (ESI,
Mþþ1) calcd for C27H27O4S 447.1630, found 447.1633; 1H NMR
(400 MHz, CDCl3):
d
7.77 (d, J¼8.4 Hz, 2H), 7.50 (dd, J¼4.4, 6.8 Hz,
CDCl3):
7.10e7.07 (m, 2H), 7.05e7.02 (m, 2H), 2.31 (s, 3H); 13C NMR
(100 MHz, CDCl3): 141.31, 138.80, 138.33, 137.32, 133.90, 132.71,
d
7.96 (s, 1H), 7.43e7.22 (m, 8H), 7.18e7.14 (m, 2H),
1H), 7.43 (d, J¼8.8 Hz, 2H), 7.36 (d, J¼8.4 Hz, 2H), 7.27 (d, J¼8.0 Hz,
2H), 7.03e7.00 (m, 3H), 6.89 (d, J¼8.8 Hz, 2H), 6.88 (d, J¼9.2 Hz, 2H),
6.73 (d, J¼16.4 Hz, 1H), 3.83 (s, 3H), 3.82 (s, 3H), 2.38 (s, 3H); 13C
d
131.23, 130.66 (2ꢁ), 130.43 (2ꢁ), 129.94, 129.06, 128.82, 128.70
(2ꢁ), 128.45, 128.39 (2ꢁ), 125.70, 21.07. Anal. Calcd for C21H18O2S:
C, 75.42; H, 5.42. Found: C, 75.71; H, 5.71.
NMR (100 MHz, CDCl3): d 160.69, 160.08, 143.77, 142.15, 137.86,
137.33, 136.76, 136.16, 129.62 (2ꢁ), 128.94 (2ꢁ), 128.86, 128.18 (2ꢁ),
127.67 (2ꢁ), 127.03, 120.24, 115.33, 114.35 (2ꢁ), 114.17 (2ꢁ), 55.35
(2ꢁ), 21.54.
4.2.20. Compound (4t). Yield¼86% (299 mg); colorless solid;
mp¼131e133 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3013, 2935, 1604, 1417, 1320, 1148, 912; HRMS (ESI, Mþþ1)
calcd for C22H21O2S 349.1262, found 349.1267; 1H NMR (400 MHz,
4.2.26. Compound (4z). Colorless solid; mp¼112e114 ꢀC (recrys-
tallized from hexanes and EtOAc); IR (CHCl3): 3048, 2959, 1611,
1365, 1142, 915; HRMS (ESI, Mþþ1) calcd for C27H22ClO2S 445.1029,
CDCl3):
d
7.95 (s, 1H), 7.52 (d, J¼8.4 Hz, 2H), 7.39e7.14 (m, 8H),
found 445.1033; 1H NMR (400 MHz, CDCl3):
d 8.01 (s,1H), 7.65e7.30
7.08e7.09 (m, 4H), 2.68 (q, J¼7.6 Hz, 2H), 1.22 (t, J¼7.6 Hz, 3H); 13
C
(m, 11H), 7.21 (d, J¼8.4 Hz, 2H), 7.20 (d, J¼8.4 Hz, 2H), 7.14 (d,
NMR (100 MHz, CDCl3):
d
150.22, 141.58, 137.23, 135.88, 132.86,
J¼8.4 Hz, 2H), 2.39 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 144.12,
131.40, 130.74 (2ꢁ), 130.48 (2ꢁ), 129.92, 129.07, 128.77 (2ꢁ), 128.74
142.65, 141.68, 141.05, 140.02, 139.85, 137.06, 135.87, 131.20, 131.04,
129.42 (2ꢁ), 128.89 (2ꢁ), 128.83 (2ꢁ), 128.67 (2ꢁ), 127.42 (2ꢁ),
127.09 (2ꢁ), 127.02 (2ꢁ), 126.95 (2ꢁ), 21.61.
(2ꢁ), 128.43 (2ꢁ), 128.15 (2ꢁ), 28.80, 15.05. Anal. Calcd for
C
22H20O2S: C, 75.83; H, 5.79. Found: C, 76.08; H, 5.88.
4.2.21. Compound (4u). Yield¼82% (297 mg); colorless solid;
mp¼120e122 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3013, 2934, 1602, 1416, 1321, 1149, 912; HRMS (ESI, Mþþ1)
calcd for C23H23O2S 363.1419, found 363.1425; 1H NMR (400 MHz,
4.2.27. Compound (4aa). Colorless solid; mp¼130e132 ꢀC
(recrystallized from hexanes and EtOAc); IR (CHCl3): 3048, 2959,
1611, 1365, 1142, 915; HRMS (ESI, Mþþ1) calcd for C27H22ClO2S
445.1029, found 445.1032; 1H NMR (400 MHz, CDCl3):
d 7.98 (s, 1H),
CDCl3):
d
7.95 (s, 1H), 7.54 (d, J¼8.4 Hz, 2H), 7.38e7.34 (m, 1H),
7.52e7.50 (m, 4H), 7.44e7.27 (m, 9H), 7.20 (d, J¼8.4 Hz, 2H), 7.01 (d,
7.30e7.21 (m, 5H), 7.17e7.13 (m, 2H), 7.08e7.02 (m, 4H), 2.96e2.89
J¼8.4 Hz, 2H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 144.31,
(m, 1H), 1.22 (d, J¼6.8 Hz, 6H); 13C NMR (100 MHz, CDCl3):
d
154.73,
142.82, 140.11, 139.70, 137.42, 135.57, 135.44, 132.17 (2ꢁ), 131.43,
130.96 (2ꢁ), 129.99, 129.49 (2ꢁ), 129.24 (2ꢁ), 128.85 (2ꢁ), 128.55
(2ꢁ), 127.93, 127.13 (2ꢁ), 126.92 (2ꢁ), 21.60.
141.55,137.12,135.88,132.75,131.31,130.62 (2ꢁ),130.37 (2ꢁ),129.84,
129.00, 128.67 (4ꢁ), 128.35 (2ꢁ), 126.69 (2ꢁ), 34.03, 23.50 (2ꢁ).
Anal. Calcd for C23H22O2S: C, 76.21; H, 6.12. Found: C, 76.40; H, 6.27.
4.2.28. Compound (5). Brown solid; mp¼192e194 ꢀC (recrystal-
lized from hexanes and EtOAc); IR (CHCl3): 3547, 3052, 2946, 2847,
1624, 1435, 1366, 1169, 915, 875; HRMS (ESI, Mþþ1) calcd for
4.2.22. Compound (4v). Yield¼80% (301 mg); colorless solid;
mp¼99e100 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3015, 2935, 1602, 1417, 1320, 1150, 913; HRMS (ESI, Mþþ1)
calcd for C24H25O2S 377.1575, found 377.1576; 1H NMR (400 MHz,
C
30H20N3 422.1657, found 422.1658; 1H NMR (400 MHz, CDCl3):
d
8.21 (d, J¼8.4 Hz, 1H), 8.16 (dd, J¼0.4, 8.4 Hz, 1H), 7.94 (dd, J¼1.2,
CDCl3):
d
7.94 (s, 1H), 7.51 (d, J¼8.4 Hz, 2H), 7.38e7.34 (m, 1H),
8.4 Hz, 1H), 7.83 (d, J¼8.4 Hz, 1H), 7.80e7.76 (m, 2H), 7.67e7.55 (m,
5H), 7.44 (d, J¼9.2 Hz, 1H), 7.40 (dt, J¼0.8, 6.8 Hz, 1H), 7.28 (d,
J¼8.4 Hz, 1H), 7.25 (br s, 1H), 7.19 (dt, J¼1.6, 6.8 Hz, 1H), 7.09 (d,
J¼9.2 Hz, 1H), 6.97e6.90 (m, 2H); 13C NMR (100 MHz, CDCl3):
7.29e7.14 (m, 7H), 7.08e7.05 (m, 2H), 7.03e7.01 (m, 2H), 2.63 (t,
J¼7.2 Hz, 2H),1.61e1.53 (m, 2H),1.39e1.26 (m, 2H), 0.91 (t, J¼7.2 Hz,
3H); 13C NMR (100 MHz, CDCl3):
d 148.96, 141.60, 137.12, 135.77,
132.85,131.40,130.73 (2ꢁ),130.48 (2ꢁ),129.92,129.05,128.74 (2ꢁ),
d 154.75, 154.51, 148.21, 148.07, 136.38, 135.39, 134.29, 132.76,
128.70 (2ꢁ), 128.67 (2ꢁ), 128.43 (2ꢁ), 35.50, 33.05, 22.10, 13.82.
129.82, 129.78, 129.58, 129.26, 129.12, 128.63, 127.68, 127.33,
127.23, 127.07, 127.00, 126.79, 126.49, 125.69 (2ꢁ), 125.29, 123.63,
121.54, 120.69, 119.15, 117.48, 104.26. Anal. Calcd for C30H19N3: C,
85.49; H, 4.54. Found: C, 85.65; H, 4.73. Single-crystal X-ray dia-
gram: crystal of compound 5 was grown by slow diffusion of
EtOAc into a solution of compound 5 in CH2Cl2 to yield colorless
prisms. The compound crystallizes in the monoclinic crystal sys-
4.2.23. Compound (4w). Yield¼82% (308 mg); colorless solid;
mp¼117e119 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3015, 2935, 1605, 1416, 1320, 1150, 912; HRMS (ESI, Mþþ1)
calcd for C24H25O2S 377.1575, found 377.1581; 1H NMR (400 MHz,
CDCl3):
7.37e7.34 (m, 1H), 7.31e7.22 (m, 3H), 7.18e7.14 (m, 2H), 7.08e7.02
(m, 4H), 1.30 (s, 9H); 13C NMR (100 MHz, CDCl3):
157.08, 141.58,
137.24, 135.59, 132.83, 131.37, 130.70 (2ꢁ), 130.45 (2ꢁ), 129.90,
129.05, 128.72 (2ꢁ), 128.45 (2ꢁ), 128.41 (2ꢁ), 125.64 (2ꢁ), 35.11,
31.00 (3ꢁ). Anal. Calcd for C24H24O2S: C, 76.56; H, 6.42. Found: C,
76.80; H, 6.53.
d
7.95 (s, 1H), 7.54 (d, J¼8.4 Hz, 2H), 7.40 (d, J¼8.8 Hz, 2H),
ꢀ
ꢀ
tem, space group P121/c1, a¼15.0399(13) A, b¼6.2472(6) A,
3
ꢀ
c¼22.3520(19) A, V¼2097.3(3) A , Z¼4, dcalcd¼1.335 g/cm3,
ꢀ
d
F(000)¼880, 2
wR2¼0.1350.
q
range 1.82e26.51ꢀ, R indices (all data) R1¼0.1152,
4.3. A representative synthetic procedure of compounds 6a,b
4.2.24. Compound (4x). Yield¼62% (239 mg); yellow viscous gum;
A representative synthetic procedure of compounds 6a,b is as
follows: compound 4a or 4p (0.2 mmol) and I2 (100 mg, 0.4 mmol)
IR (CHCl3): 3582, 2938, 1598, 1401, 1302, 1144, 931; HRMS (ESI,

1746
M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
were dissolved in EtOAc (15 mL) at rt. Then, 1,2-epoxybutane
(440 mg, 6.0 mmol) was added to the reaction mixture and irra-
252,
wR2¼0.1089.
2
q
range 2.06e26.28ꢀ,
R
indices (all data) R1¼0.0429,
ꢀ
diated under a nitrogen atmosphere with a lamp (
l
¼2540 A), using
a Pyrex glass filter at rt for 80 h. The solvent was evaporated to
afford crude product. Purification on silica gel (hexanes/EtOAc¼8:1
to 2:1) afforded compounds 6a,b.
Acknowledgements
The authors would like to thank the National Science Council of
the Republic of China for its financial support (NSC 102-2113-M-
037-005-MY2).
4.3.1. Compound (6a). Yield¼72% (48 mg); colorless solid;
mp¼170e171 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3533, 3023, 2946, 1614, 1427, 1320, 1142, 923; HRMS (ESI,
Mþþ1) calcd for C21H17O2S 333.0949, found 333.0952; 1H NMR
Supplementary data
(400 MHz, CDCl3):
d
8.90 (s, 1H), 8.71e8.64 (m, 3H), 8.09 (dd, J¼2.4,
Scanned photocopies of 1H and 13C NMR spectral data were
supported. Supplementary data associated with this article can be
found in the online version, at http://dx.doi.org/10.1016/
j.tet.2014.01.045.
8.0 Hz, 1H), 7.88 (d, J¼8.4 Hz, 2H), 7.83 (dt, J¼1.6, 8.4 Hz, 1H), 7.71
(dt, J¼0.8, 8.0 Hz, 1H), 7.66 (dt, J¼1.6, 8.0 Hz, 1H), 7.60 (dt, J¼1.6,
8.4 Hz, 1H), 7.25 (d, J¼8.4 Hz, 2H), 2.35 (s, 3H); 13C NMR (100 MHz,
CDCl3):
d 144.02, 138.62, 134.57, 132.70, 131.25, 130.74, 129.99,
129.75 (3ꢁ), 129.35,127.62 (2ꢁ), 127.46 (3ꢁ),126.00,125.45,123.27,
122.74, 21.51. Anal. Calcd for C21H16O2S: C, 75.88; H, 4.85. Found: C,
76.03; H, 4.98. Single-crystal X-ray diagram: crystal of 6a was
grown by slow diffusion of EtOAc into a solution of 6a in CH2Cl2 to
yield colorless prisms. The compound crystallizes in the triclinic
References and notes
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Y. J. J. Med. Chem. 2012, 55, 5720.
ꢀ
ꢀ
crystal system, space group P-1, a¼8.9084(9) A, b¼9.2635(9) A,
3
c¼10.4687(9) A, V¼783.84(13) A , Z¼2, dcalcd¼1.408 g/cm3, F(000)¼
ꢀ
ꢀ
348,
2q
range 2.07e26.39ꢀ,
R
indices (all data) R1¼0.0533,
wR2¼0.1554.
2. (a) Walter, G.; Liebl, R.; Von Angerer, E. Bioorg. Med. Chem. 2004, 14, 4659; (b)
Chavez, D.; Chai, H. B.; Chagwedera, T. E.; Gao, Q.; Farnsworth, N. R.; Cordell, G.
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H.; Farnsworth, N. R.; Kinghorn, A. D.; Mehta, R. G.; Moon, R. C.; Pezzuto, J. M.
Science 1997, 275, 218.
4.3.2. Compound (6b). Yield¼70% (45 mg); colorless solid;
mp¼159e161 ꢀC (recrystallized from hexanes and EtOAc); IR
(CHCl3): 3533, 3023, 2946, 1615, 1427, 1323, 1142, 922; HRMS (ESI,
Mþþ1) calcd for C20H15O2S 319.0793, found 319.0785; 1H NMR
ꢁ
3. Ducrot, P.-H.; Kollmann, A.; Bala, A. E.; Majira, A.; Kerhoas, L.; Delorme, R.;
Einhorn, J. Tetrahedron Lett. 1998, 39, 9655.
(400 MHz, CDCl3):
d
8.92 (s, 1H), 8.71 (dd, J¼0.8, 8.8 Hz, 1H), 8.69
(d, J¼8.4 Hz, 1H), 8.63 (dd, J¼0.8, 8.4 Hz, 1H), 8.11 (dd, J¼0.8,
8.4 Hz, 1H), 8.02e7.99 (m, 2H), 7.83 (dt, J¼1.6, 8.4 Hz, 1H),
7.74e7.58 (m, 3H), 7.55e7.44 (m, 3H); 13C NMR (100 MHz, CDCl3):
4. Iliya, I.; Ali, Z.; Tanaka, T.; Iinuma, M.; Furusawa, M.; Nakaya, K.-i.; Murata, J.;
Darnaedi, D.; Matsuura, N.; Ubukata, M. Phytochemistry 2003, 62, 601.
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G. J.; Jefferies, G.; Hamilton, D. G.; Lynch, D. E.; Roberts, M. P. S.; Bahra, G. S.;
Brown, C. R. Nature 1995, 375, 385; (d) Chen, C.-T.; Marder, S. R.; Cheng, L.-T. J.
Chem. Soc., Chem. Commun. 1994, 259.
7. (a) Imai, M.; Arai, T. Tetrahedron Lett. 2002, 43, 5265; (b) Meier, H. Angew. Chem.,
Int. Ed. Engl. 1992, 31, 1399; (c) Waldeck, D. H. Chem. Rev. 1991, 91, 415.
8. (a) Perkin, W. H. J. Chem. Soc. 1868, 181; (b) Sinha, A. K.; Kumar, V.; Sharma, A.;
Sharma, A.; Kumar, R. Tetrahedron 2007, 63, 11070; (c) Solladie, G.; Pasturel-
Jacope, Y.; Maignan, J. Tetrahedron 2003, 59, 3315.
d
141.62, 134.21, 133.67, 133.09, 132.79, 131.28, 130.80, 130.12,
129.14 (2ꢁ), 128.63, 127.69 (2ꢁ), 127.54, 127.37 (2ꢁ), 125.99,
125.42, 123.32, 122.78. Anal. Calcd for C20H14O2S: C, 75.45; H, 4.43.
Found: C, 75.62; H, 4.70.
4.4. A representative synthetic procedure of compounds 7aec
9. (a) Eichen, Y.; Nakhmanovich, G.; Gorelik, V.; Epshtein, O.; Poplawski, J. M.;
Ehrenfreund, E. J. Am. Chem. Soc. 1998, 120, 10463; (b) Rao, V. P.; Jen, A. K.-Y.;
Wong, K. Y.; Drost, K. J. Tetrahedron Lett. 1993, 34, 1747; (c) Diez-Barra, E.;
Garcia-Martinez, J. C.; Rodriguez-Lopez, J. Tetrahedron Lett. 1999, 40, 8181; (d)
Wang, M.; Jin, Y.; Ho, C.-T. J. Agric. Food Chem. 1999, 47, 3974; (e) Meier, H.;
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2007, 72, 7337.
10. (a) Chalal, M.; Vervandier-Fasseur, D.; Meunier, P.; Cattey, H.; Hierso, J.-C. Tet-
rahedron 2012, 68, 3899; (b) Salabert, J.; Sebastian, R. M.; Vallribera, A.; Cívicos,
J. F.; Najera, C. Tetrahedron 2013, 69, 2655; (c) Reeves, D. C.; Rodriguez, S.; Lee,
H.; Haddad, N.; Krishnamurthy, D.; Senanayake, C. H. Tetrahedron Lett. 2009, 50,
2870; (d) Belfield, K. D.; Chinna, C.; Schafer, K. J. Tetrahedron Lett. 1997, 38, 6131;
(e) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457; (f) Herrmann, W. A. Angew.
Chem., Int. Ed. 2002, 41, 1290; (g) Chatterjee, A. K.; Grubbs, R. H. Org. Lett. 2000,
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McMurry, J. E.; Fleming, M. P. J. Am. Chem. Soc. 1974, 96, 4708.
A representative synthetic procedure of compounds 7aec is as
follows: t-BuOK (224 mg, 2.0 mmol) was added to a stirred solution
of compounds 4a, 4d,e (0.5 mmol) in THF (15 mL) at rt. The reaction
mixture was stirred at reflux for 1 h. The reaction mixture was
cooled to rt, concentrated, and extracted with CH2Cl2 (3ꢁ30 mL).
The combined organic layers were washed with brine, dried, fil-
tered, and evaporated to afford crude products under reduced
pressure. Purification on silica gel (hexanes/EtOAc¼100:1 to 50:1)
afforded compounds 7aec.
4.4.1. Compound (7a).21 Yield¼75% (67 mg); 1H NMR (400 MHz,
CDCl3):
d 7.54e7.50 (m, 4H), 7.32e7.28 (m, 6H).
11. (a) Liu, K. H.; Masuda, A.; Yamazaki, Y. Tetrahedron Lett. 1975, 3007; (b) Savo-
lainen, M. A.; Wu, J. Org. Lett. 2013, 15, 3802; (c) Hauser, C. R.; Brasen, W. R.;
Skell, P. S.; Kantor, S. W.; Brodhag, A. E. J. Am. Chem. Soc. 1956, 78, 1653.
12. (a) Gans, K.-R.; Galbraith, W.; Roman, R.-J.; Haber, S.-B.; Kerr, J.-S.; Schmidt, W.-
K.; Smith, C.; Hewes, W.-E.; Ackerman, N.-R. J. Pharmacol. Exp. Ther. 1990, 254,
180; (b) Garland, L. L.; Taylor, C.; Pilkington, D. L.; Cohen, J. L.; von Hoff, D. D.
Clin. Cancer Res. 2006, 12, 5182; (c) Khanapure, S.-P.; Garvey, D.-S.; Young, D.-V.;
Ezawa, M.; Earl, R.-A.; Gaston, R.-D.; Fang, X.; Murty, M.; Martino, A.; Shumway,
M.; Trocha, M.; Marek, P.; Tam, S.-W.; Janero, D.-R.; Letts, L.-G. J. Med. Chem.
2003, 46, 5484; (d) Friesen, R.-W.; Brideau, C.; Chan, C.-C.; Charleson, S.; De-
schenes, D.; Dube, D.; Ethier, D.; Fortin, R.; Gauthier, J.-Y.; Firard, Y.; Gordon, R.;
Freig, G.-M.; Riendeau, D.; Savoie, C.; Wang, Z.; Wong, E.; Visco, D.; Xu, J.-L.;
Young, R.-N. Bioorg. Med. Chem. Lett. 1998, 8, 2777.
4.4.2. Compound (7b).22 Yield¼66% (79 mg); 1H NMR (400 MHz,
CDCl3):
d
7.44 (d, J¼8.8 Hz, 4H), 6.85 (d, J¼8.8 Hz, 4H), 3.78 (s, 6H).
4.4.3. Compound (7c).23 Yield¼70% (86 mg); colorless solid;
mp¼175e177 ꢀC (recrystallized from hexanes and EtOAc); 1H NMR
(400 MHz, CDCl3):
d
7.45 (d, J¼8.4 Hz, 4H), 7.33 (d, J¼8.4 Hz, 4H).
Single-crystal X-ray diagram: crystal of 7c was grown by slow dif-
fusion of EtOAc into a solution of 7c in CH2Cl2 to yield colorless
prisms. The compound crystallizes in the monoclinic crystal sys-
13. (a) Chang, M.-Y.; Wu, M.-H.; Chen, Y.-L. Org. Lett. 2013, 15, 2822; (b) Chang, M.-
Y.; Chan, C.-K.; Wu, M.-H. Tetrahedron 2013, 69, 7916; (c) Chang, M.-Y.; Chan, C.-
K.; Lin, S.-Y.; Wu, M.-H. Tetrahedron 2013, 69, 10036.
ꢀ
ꢀ
tem, space group P121/c1, a¼9.9057(9) A, b¼4.8954(5) A,
c¼11.1324(11) A, V¼538.53(9) A , Z¼2, dcalcd¼1.524 g/cm3, F(000)¼
3
ꢀ
ꢀ

M.-Y. Chang et al. / Tetrahedron 70 (2014) 1740e1747
1747
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(4l), 960187(5), 957797 (6a) and 958040 (7c) contain the supplementary
crystallographic data for this paper. This data can be obtained free of charge via
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