Visible-Light-Driven, Palladium-Catalyzed Heck Reaction of Internal Vinyl Bromides with Styrenes

Article abstract of DOI:10.1021/acs.joc.1c00838

Functionalized 1,3-dienes were efficiently accessed from visible-light-driven, palladium-catalyzed Heck reaction of S,S-functionalized internal vinyl bromides with styrenes under mild conditions. This Heck reaction showcased tolerance of a wide array of f

Full text of DOI:10.1021/acs.joc.1c00838

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Article
Visible-Light-Driven, Palladium-Catalyzed Heck Reaction of Internal
Vinyl Bromides with Styrenes
Yunlong Li,# Haibo Liu,# Zilong Huang, Yuan He, Bao-Hua Xu, Hongmei Wang,* and Zhengkun Yu*
Cite This: J. Org. Chem. 2021, 86, 8402−8413
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ABSTRACT: Functionalized 1,3-dienes were efficiently accessed
from visible-light-driven, palladium-catalyzed Heck reaction of S,S-
functionalized internal vinyl bromides with styrenes under mild
conditions. This Heck reaction showcased tolerance of a wide array
of functional groups, afforded the target products in moderate to
excellent yields through a radical reaction pathway. The resultant
diene products could be further transformed to highly functionalized trisubstituted furan derivatives.
photoredox radical mechanism.14 Weiss and co-workers
recently reported that energy transfer from CdS QDs to a
photogenerated palladium complex could increase the rate and
selectivity of a Pd-photocatalyzed Heck reaction for the
synthesis of 2-cyclohexylstyrenes under mild conditions
(Scheme 1b).15
INTRODUCTION
■
Transition-metal-catalyzed Heck coupling1,2 between active
olefins and aryl or vinyl halides under basic conditions has
become one of the most powerful methods for C−C bond
formation.3 For Heck-type alkenylation, much attention has
been paid to the development of coupling partners including
alkyl,4 aryl,5 and vinyl6 halides as well as arylboronic acids,7
and in some cases aryl radical can be generated with the aid of
a transition-metal catalyst and oxidant. However, in most of
the cases, terminal alkenes were applied in the Heck-type
cross-coupling reaction, and internal vinyl halides have seldom
been applied as the coupling partners.8
Although photocatalytic Heck reactions have recently been
paid much attention,16 the cross-coupling of internal vinyl
halides with terminal alkenes has rarely been reported.8 To
realize such a cross-coupling reaction, the low reactivity of the
internal vinylic C-halide bonds should be overcome. We
previously introduced a structural element, that is, 1,2-dithiane
functionality, at one terminus of an olefinic CC bond, and
an electron-withdrawing group at its other end, to polarize the
vinyl CC backbone by an electronic push-pull effect,
activating the internal olefinic C−H bond.17 Featuring such
an activation mode, we found that the olefinic C−H bonds of
S,S-functionalized internal alkenes could undergo oxidative
Heck-type cross-coupling with activated terminal alkenes such
as acrylates and styrenes (2.5−3.0 equiv) in the presence of a
high loading of a catalyst (20 mol % Pd(OAc)2) to afford 1,3-
dienes (Scheme 1c).17b When the terminal alkenes were
styrenes, two isomeric diene products were usually produced.
Thus, we envisioned that S,S-functionalized internal vinyl
halides with reactivity enhanced by the push-pull effect might
be applied in transition-metal-catalyzed Heck cross-coupling
with alkenes. Herein, we disclose a visible-light-driven,
palladium-catalyzed Heck-type cross-coupling of S,S-function-
Visible-light-driven catalysis has emerged as a powerful tool
for the construction and functionalization of structurally
diverse compounds in organic synthesis.9 The combination
of photoredox and transition-metal catalysis expands the scope
of coupling partners by alternating the reaction pathways.10
The photocatalytic reaction always starts with excitation of the
photocatalyst by visible light, which usually gets one electron
from the reagents through a single electron transfer (SET)
process to initiate the reaction.11 C−H bonds can be used as
the nucleophile precursors for C−C bond formation through
triple catalysis of photocatalysis, hydrogen atom transfer, and
̈
transition-metal catalysis. Kohler and co-workers reported first
UV- and visible-light-induced Heck reaction of bromobenzene
with styrenes catalyzed by Pd(OAc)2 in 2010, indicating that
irradiation with UV and visible light could significantly
improve the rate of the Heck reaction (Scheme 1a).12 Shang
and Fu et al. documented the photo-induced palladium-
catalyzed Heck reaction of terminal alkenes with alkyl halides
at room temperature.13a13b The Gevorgyan group13c and
13d
Received: April 12, 2021
Published: May 27, 2021
́
Novak lab reported similar catalytic systems for the Heck
reaction of styrenes with tertiary alkyl halides and fluoroalkyl
iodides, respectively, in this area. Very recently, Gevorgyan et
al. realized light-induced Pd-catalyzed alkyl-Heck reaction of
oximes.13e Jui et al. developed a mild catalytic process enabling
the general hydro-heteroarylation of simple alkenes via a
https://doi.org/10.1021/acs.joc.1c00838
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Scheme 1. Visible-Light-Driven, Transition-Metal-Catalyzed Heck Cross-Couplings of Alkenes
a
alized internal vinyl bromides with styrenes to access 1,3-
dienes (Scheme 1d).
Table 1. Screening of Conditions
RESULTS AND DISCUSSION
■
Initially, the reaction of 2-bromo-3,3-bis(methylthio)-1-phe-
nylprop-2-en-1-one (1a) with 4-chlorostyrene (2a) was
conducted to optimize the reaction conditions (Table 1).
With 10 mol % Pd(OAc)2 as the catalyst, 20 mol % XantPhos
as the ligand, and 2 equiv of Cs2CO3 as the base, the reaction
of 1a and 2a in a 1.0:1.5 molar ratio underwent in benzene at
ambient temperature under visible-light irradiation of a 15 W
blue LED bulb. The target product, that is, (E)-2-(bis-
(methylthio)methylene)-4-(4-chlorophenyl)-1-phenylbut-3-
en-1-one (3a), was obtained in 65% isolated yield after the
reaction mixture was stirred under irradiation for 12 h (Table
1, entries 1−4). Use of benzene as the solvent is crucial for the
success of the reaction. Pd(OAc)2 acted as the most efficient
catalyst among the screened palladium sources Pd(OAc)2,
Pd(TFA)2, PdCl2(PPh3)2, PdCl2(MeCN)2, Pd2(dba)3, and
Pd(PPh3)4 (Table 1, entries 4−9). After further screening the
catalyst loadings and substrate ratios, the optimal conditions
were achieved to give 3a in 76% isolated yield (Table 1, entry
14). It is noteworthy that the reaction did not occur without
the light irradiation nor in the absence of either of the
palladium catalyst and Cs2CO3 base or under heating at 110
°C (see the Supporting Information for details).
b
entry
catalyst (mol %)
Cs2CO3 (equiv)
solvent
yield (%)
1
2
3
4
5
6
7
8
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(TFA)2 (10)
PdCl2(PPh3)2 (10)
PdCl2(MeCN)2 (10)
Pd2(dba)3 (10)
Pd(PPh3)4 (10)
Pd(OAc)2 (4)
Pd(OAc)2 (6)
Pd(OAc)2 (8)
Pd(OAc)2 (6)
Pd(OAc)2 (6)
Pd(OAc)2 (6)
Pd(OAc)2 (6)
2
2
2
2
2
2
2
2
2
2
2
2
1.8
2.2
2.2
2.2
2.2
DMF
0
0
10
c
dioxane
toluene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
benzene
71 (65)
26
0
34
7
9
56
49
76
74
68
10
11
12
13
14
c
80 (76)
d
15
de
0
0
0
0
,
16
17
18
Pd(OAc)2 (6)
a
Conditions: 1a (0.3 mmol), 2a (0.45 mmol), catalyst (4−12 mol %),
Under the optimal conditions, the scope of styrenes (2) was
explored (Scheme 2). The analogs of 2a, that is, 3- and 2-
chloro-substituted styrenes, exhibited a similar reactivity to
form the target 1,3-diene products 3b (71%) and 3c (70%),
respectively. p-F-Styrene efficiently reacted with 1a to give the
corresponding product 3d in 83% yield. 4-Trifluoromethyl and
XantPhos (20 mol %), solvent (3 mL), 15 W blue LED, 25 °C, 0.1
b
MPa N2, 12 h. The yields were determined by 1H NMR analysis with
c
1,3,5-trimethoxybenzene as an internal standard. Isolated yield given
d
e
in parentheses. Without LED irradiation. 110 °C.
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a
Scheme 2. Scope of Styrenes (2)
a
Conditions: 1a (0.3 mmol), 2 (0.45 mmol), Pd(OAc)2 (0.018 mmol), XantPhos (0.06 mmol), Cs2CO3 (0.66 mmol), benzene (3 mL), 25 °C, 15
W blue LED, 0.1 MPa N2, 12 h.
4-acetoxy exhibited no obvious negative electronic impact on
the yields of 3e (74%) and 3f (71%). However, the strong
electron-withdrawing group 4-cyano led to formation of both
the corresponding product 3g and its inseparable isomer 3g′
(7:1) in 68% yield, which is similar to the palladium-catalyzed
oxidative Heck cross-coupling between styrenes and S,S-
functionalized internal alkenes17b or acrylates.18 Methyl-
substituted styrenes reacted well with 1a to afford products
3h and 3i in 73−75% yields, and in the case of using 2-
methylstyrene, a slightly negative steric effect was observed to
diminish the yield of 3j to 68%. Both 4-methoxy and 4-tert-
butyl facilitated the reaction to form 3k and 3l (79−81%),
respectively. Unsubstituted styrene (2m) also efficiently
reacted with 1a to generate the target product (3m, 71%).
Notably, a decreased yield (50%) for (E)-2-(bis(methylthio)-
methylene)-4-(naphthalen-2-yl)-1-phenylbut-3-en-1-one (3n)
was obtained due to the steric hindrance from the 2-naphthyl
group in the terminal alkene substrate.
efficiently reacted with styrene to yield the corresponding
product 4a (82%). Substituents 4-F, 4-CF3, 4-Me, and 3-Me
facilitated the reaction to form the target products 4b, 4c, 4e,
and 4f in 70−79% yields, while 3-CF3 and 2-Me exhibited a
negative electronic/steric effect on the formation of 4d (62%)
and 4g (51%), respectively. α-(4-Ethylbenzoyl)-functionalized
vinyl bromide (1i) showed a lower reactivity than its α-toloyl
analog (1f) to form 4h (65%), whereas 4e was accessed in 79%
yield. 4-Methoxy facilitated the reaction to give 4i (73%), but
2-MeO diminished the reaction efficiency to form 4j (43%).
Sterically hindered 2-naphthyl had an obvious negative steric
effect on the reaction. α-Thienoyl-based vinyl bromide also
reacted with styrene to afford the corresponding product 4l
(65%). It should be noted that α-pivaloyl-based vinyl bromide
(1n) effectively reacted with styrene to give 4m (59%) and its
α-acetyl analog (1o) exhibited no reactivity under the same
conditions. However, its cyclic α-acetyl analog (1p) reacted
well with styrene to produce 4o (63%), demonstrating a
remarkable steric/electronic effect from the α-oxo moiety in
substrates 1. In a similar fashion, the cyclic and diethylthio
analogs of 1a, that is, 1q and 1r, efficiently reacted with styrene
to give 4p (71%) and 4q (74%), respectively. α-Aroyl vinyl
bromides could also react with various substituted styrenes to
form the target 1,3-diene products 4r−4x (52−75%). In the
Next, the protocol generality was investigated by performing
the reaction of various vinyl halides 1 with styrene (2m) and
its analogs (Scheme 3). The substituents on the α-aroyl
moieties of compounds 1 exhibited obvious impacts on the
yields of the target products 4. Under the standard conditions,
α-(4-bromobenzoyl) S,S-functionalized vinyl bromide (1b)
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a
Scheme 3. Scope of Internal Vinyl Bromides (1)
a
Conditions: 1 (0.3 mmol), 2 (0.45 mmol), Pd(OAc)2 (0.018 mmol), XantPhos (0.06 mmol), Cs2CO3 (0.66 mmol), benzene (3 mL), 25 °C, 15
W blue LED, 0.1 MPa N2, 12 h.
cases of using di- and trisubstituted styrenes, the reaction
efficiency was very poor or no reaction occurred. Notably, the
present reaction regioselectively formed the conjugate dienes
of type 4 without generation of isomeric dienes of type 3g′ as
the coalesced side products, which were generally produced in
the thermal palladium-catalyzed reactions developed by Loh18
and Yu et al.17b
It should be noted that the corresponding internal vinyl
chloride and iodide of type 1, that is, 5a and 5b, were subjected
to the standard reaction conditions to react with styrene (2m),
affording the target product 3m in 20−24% yields (eq 1),
revealing that the chloride and iodide of type 1 are not the
suitable coupling partners under the stated conditions. The
control experiments of vinyl bromide 1a with styrenes 2e/2k
and vinyl bromides 1d/1f with styrene 2m by shortening the
reaction time to 4 h differentiate the substrate reactivity as
demonstrated in eqs 2 and 3, respectively. Electron-donating 4-
OMe-substituted styrene (2k) exhibited a higher reactivity
than electron-withdrawing 4-CF3-substituted styrene (2e) (eq
2), and 4-CF3-substituted vinyl bromide (1d) reacted more
efficiently than electron-donating 4-Me-substituted vinyl bro-
mide (1f) (eq 3).
Furan is a key structural unit in many natural products,
pharmaceuticals, and biologically relevant synthetic mole-
cules.19 In our case, the Heck-type 1,3-diene products of 3
and 4 could be efficiently transformed to the corresponding
2,3,5-trisubstituted furans 6 (Scheme 4). In the presence of
NBS as the promoter/reactant in the mixed solvent CH3CN/
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Scheme 4. Derivatization of 1,3-Dienes (3 and 4)
Figure 1. Profile for the formation of 3m from the reaction of 1a and
2m with light on/off over time.
Scheme 5. Proposed Mechanism
H2O (50:1, v/v), the target furan derivatives 6a−6h were
obtained in 63−71% yields under mild conditions, which has
demonstrated a potential application of the present synthetic
methods.
To gain insight into the reaction mechanism, radical
scavengers 2,2,6,6-tetramethyl-1-piperidyloxy (TEMPO) and
2,6-di-tert-butyl-4-methylphenol (BHT) and radical inhibitor
PhNO2 were introduced to the reaction system of internal
vinyl bromide 1a and styrene (2m) under the standard
conditions, respectively. All the three reagents completely
inhibited the Heck-type alkenylation reaction, and species 7
was detected in the reaction mixture by HRMS determination
(see the Supporting Information for details), but it was not
successfully isolated (eq 4), which suggests that a radical
pathway might be involved in the coupling reaction.20 The
formation of 3m from the reaction of 1a and 2m was also
monitored with light on/off over time21 (Figure 1). Smooth
transformation occurred under blue LED irradiation, and no
product increase was observed in the dark, revealing a
photoredox catalytic mechanism (see the Supporting Informa-
tion for details).
catalyst, the reaction did not occur (Table 1, entry 17). Species
A undergoes an SET process with internal vinyl bromide 1 to
form the putative LnPd(I)Br species and vinyl radical B under
LED irradiation. Interaction of B with styrene 2 produces
radicals C/C′. Subsequent β-H-elimination delivers the target
product 1,3-diene 3/4 and/or the side product 3′ with release
of the Pd(II) species LnHPd(II)Br. Reductive elimination
regenerates species A by removal of HBr from species
LnHPd(II)Br by the base, completing the catalytic cycle.
In summary, visible-light-driven, palladium-catalyzed Heck
cross-coupling of S,S-functionalized internal vinyl bromides
with styrenes has been efficiently realized under mild
A plausible mechanism is proposed in Scheme 5. Initially,
the active Pd(0) species A is generated by the in situ reduction
of Pd(OAc)2 with the ligand and absorbs light to promote the
reaction.22 It is noted that, in the absence of the palladium
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2.50 and 2.02 (s each, 3:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ
191.0, 140.4, 140.0, 135.5, 132.2, 132.0, 130.5, 125.4, 120.3, 21.4,
18.3, and 16.5. HRMS (EI) m/z calcd for C12H14OS2Br [M + H]+:
316.9669; Found: 316.9669.
2-Bromo-1-(4-ethylphenyl)-3,3-bis(methylthio)prop-2-en-1-one
(1i). 265 mg, 80% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 2:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.83 (d, J = 8.2 Hz, 2 H), 7.30 (d, J = 8.2 Hz, 2 H), 2.71 (q,
2 H), 2.46 and 2.15 (s each, 3:3 H), 1.26 (t, J = 7.6 Hz, 3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 189.0, 151.2, 137.8, 132.2,
conditions, providing an alternative route to highly function-
alized 1,3-dienes and exhibiting a potential to access 2,3,5-
trisubstituted furans. The present results have demonstrated a
strategy for internal vinyl C-halide bonds to undergo
regioselective radical Heck reactions.
EXPERIMENTAL SECTION
■
General Considerations. The solvents were dried and distilled
prior to use by the literature methods. 1H and 13C{1H} NMR spectra
were recorded on a 400 MHz spectrometer, and all chemical shift
values refer to CDCl3 (δ (1H), 7.26 ppm; δ (13C), 77.16 ppm). High-
resolution mass spectra were measured on a GC-TOF mass
spectrometer. All the melting points were measured and uncorrected.
Analytical TLC plates were viewed by UV light (254 nm). Column
chromatographic purifications were performed on SDZF silica gel
160. The starting chemical reagents were purchased from commercial
sources and used as received unless otherwise indicated. Compounds
internal vinyl bromides (1),23 internal vinyl chloride (5a),23 and
iodide (5b)24 were prepared by the reported procedures. Compounds
1a,23 1f,23 1j,23 1l,23 1n,23 1p,23 1q,23 1r,23 3m,19a 4a,19a 4e,19a 4i,19a
4o,17b 4p,25 6a,19a and 6e19a are known, and their NMR spectroscopic
features are consistent with those reported previously.
130.1, 128.4, 118.2, 29.1, 19.0, 16.3, and 15.2. HRMS (EI) m/z calcd
for C13H16OS2Br [M + H]+: 330.9825; Found: 330.9826.
2-Bromo-1-(2-methoxyphenyl)-3,3-bis(methylthio)prop-2-en-1-
one (1k). 240 mg, 72% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.74 (m, 1 H), 7.47 (m, 1 H), 6.99 (t, J = 7.5 Hz, 1 H),
6.94 (d, J = 8.4 Hz, 1 H), 3.84, 2.42 and 2.04 (s each, 3:3:3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 188.3, 159.1, 137.5, 134.6,
131.9, 125.7, 121.9, 120.6, 112.0, 55.9, 18.4, and 16.5. HRMS (EI) m/
z calcd for C12H14O2S2Br [M + H]+: 332.9618; Found: 332.9619.
2-Bromo-3,3-bis(methylthio)-1-(thiophen-2-yl)prop-2-en-1-one
(1m). 220 mg, 71% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.71 (m, 1 H), 7.62 (m, 1 H), 7.12 (m, 1 H), 2.44 and 2.17
(s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 181.8, 141.6,
139.0, 135.6, 134.7, 128.4, 116.8, 19.2, and 16.4. HRMS (EI) m/z
calcd for C9H10OS3Br [M + H]+: 308.9077; Found: 308.9077.
3-Bromo-4,4-bis(methylthio)but-3-en-2-one (1o). 176 mg, 73%
yield (eluent: petroleum ether (60−90 °C)/dichloromethane, 3:1, v/
v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 2.46, 2.44 and 2.33
(s each, 3:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 195.0, 142.4,
120.4, 29.4, 19.7, and 17.1. HRMS (EI) m/z calcd for C6H10OS2Br
[M + H]+: 240.9356; Found: 240.9356.
2-Bromo-1-(4-bromophenyl)-3,3-bis(methylthio)prop-2-en-1-
one (1b). 336 mg (eluent: petroleum ether (60−90 °C)/ethyl acetate,
1
10:1, v/v), 88% yield, yellow liquid. H NMR (400 MHz, CDCl3) δ
7.76 (m, 2 H), 7.63 (m, 2 H), 2.48 and 2.15 (s each, 3:3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 188.3, 139.2, 133.7, 132.3, 131.2, 129.3,
117.1, 19.1, and 16.4. HRMS (EI) m/z calcd for C11H11OS2Br2 [M +
H]+: 380.8618; Found: 380.8618.
2-Bromo-1-(4-fluorophenyl)-3,3-bis(methylthio)prop-2-en-1-one
(1c). 289 mg, 90% yield (eluent: petroleum ether (60−90 °C)/ethyl
acetate, 10:1, v/v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.91
(m, 2 H), 7.14 (m, 2 H), 2.45 and 2.13 (s each, 3:3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 187.7, 166.2 (d, J = 254.9 Hz), 138.7,
132.4 (d, J = 9.5 Hz), 131.0 (d, J = 2.8 Hz), 117.2, 116.1 (d, J = 21.9
Hz), 18.9, and 16.3. 19F NMR (400 MHz, CDCl3) δ −103.4. HRMS
(EI) m/z calcd for C11H11OS2FBr [M + H]+: 320.9418; Found:
320.9419.
General Procedure for the Synthesis of 1,3-Dienes 3 and 4.
A Typical Procedure for the Synthesis of (E)-2-(Bis(methylthio)-
methylene)-4-(4-chlorophenyl)-1-phenylbut-3-en-1-one (3a). A
mixture of 2-bromo-3,3-bis(methylthio)-1-phenylprop-2-en-1-one
(1a) (91 mg, 0.3 mmol), 4-chlorostyrene (2a) (62 mg, 0.45
mmol), Pd(OAc)2 (4 mg, 0.018 mmol), XantPhos (35 mg, 0.06
mmol), and Cs2CO3 (215 mg, 0.66 mmol) in 3 mL of benzene was
stirred at ambient temperature under visible-light irradiation of a 15
W blue LED bulb (450−460 nm) for 12 h. After complete
consumption of 1a by TLC monitoring, EtOAc (10 mL) and
saturated aqueous NaCl (10 mL) were successively added. The
organic phase was separated, and the aqueous phase was extracted
with EtOAc (3 × 10 mL). The combined organic phase was washed
with water (3 × 10 mL), dried over anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The resultant mixture was
subjected to purification by column chromatography on silica gel
(eluent: petroleum ether (60−90 °C)/dichloromethane = 20:1, v/v)
2-Bromo-3,3bis(methylthio)-1-(4-(trifluoromethyl)phenyl)prop-
2-en-1-one (1d). 316 mg, 85% yield (eluent: petroleum ether (60−90
1
°C)/dichloromethane, 3:1, v/v), yellow liquid. H NMR (400 MHz,
CDCl3) δ 7.99 (d, J = 8.1 Hz, 2 H), 7.73 (d, J = 8.2 Hz, 2 H), 2.46
and 2.11 (s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 188.0,
140.2, 137.9, 134.8 (q, J = 32.6 Hz), 129.9, 125.8 (q, J = 3.7 Hz),
123.5 (q, J = 271.3 Hz), 116.5, 18.9, and 16.3. 19F NMR (400 MHz,
CDCl3) δ −63.1. HRMS (EI) m/z calcd for C12H11OS2F3Br [M +
H]+: 370.9386; Found: 370.9383.
2-Bromo-3,3-bis(methylthio)-1-(3-(trifluoromethyl)phenyl)prop-
2-en-1-one (1e). 290 mg, 78% yield (eluent: petroleum ether (60−90
1
1
°C)/ethyl acetate, 10:1, v/v), yellow liquid. H NMR (400 MHz,
to afford 3a as a yellow liquid (82 mg, 76%). H NMR (400 MHz,
CDCl3) δ 8.14 (s, 1 H), 8.04 (d, J = 7.8 Hz, 1 H), 7.83 (d, J = 7.7 Hz,
1 H), 7.62 (t, J = 7.8 Hz, 1 H), 2.47 and 2.12 (s each, 3:3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 187.8, 140.4, 135.6, 132.8, 131.5
(q, J = 32.8 Hz), 130.1 (q, J = 3.5 Hz), 129.5, 126.2 (q, J = 3.8 Hz),
123.6 (q, J = 271.1 Hz), 116.4, 18.8, and 16.4. 19F NMR (400 MHz,
CDCl3) δ −62.8. HRMS (EI) m/z calcd for C12H11OS2F3Br [M +
H]+: 370.9386; Found: 370.9387.
2-Bromo-3,3-bis(methylthio)-1-(m-tolyl)prop-2-en-1-one (1g).
206 mg, 65% yield (eluent: petroleum ether (60−90 °C)/dichloro-
methane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.72
(s, 1 H), 7.66 (d, J = 7.4 Hz, 1 H), 7.36 (m, 2 H), 2.45, 2.39 and 2.11
(s each, 3:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 189.3, 138.7,
138.1, 134.7, 134.6, 129.9, 128.6, 127.1, 117.9, 21.3, 18.8, and 16.3.
HRMS (EI) m/z calcd for C12H14OS2Br [M + H]+: 316.9669; Found:
316.9670.
CDCl3) δ 7.95 (m, 2 H), 7.58 (m, 2 H), 7.48 (t, J = 7.6 Hz, 2 H),
7.30 (m, 2 H), 7.25 (m each, 1:1 H), 6.29 (d, J = 16.5 Hz, 1 H), 2.43
and 2.14 (s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.2,
145.1, 136.8, 136.6, 135.4, 133.9, 133.7, 132.0, 129.4, 128.9, 128.0,
125.3, 17.5, and 16.8. HRMS (EI) m/z calcd for C19H18OS2Cl [M +
H]+: 361.0487; Found: 361.0488.
(E)-2-(Bis(methylthio)methylene)-4-(3-chlorophenyl)-1-phenyl-
but-3-en-1-one (3b). 77 mg, 71% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.95 (m, 2 H), 7.60 (m, 2 H), 7.48 (t, J = 7.6
Hz, 2 H), 7.38 (s, 1 H), 7.20 (m each, 2:1 H), 6.27 (d, J = 16.5 Hz, 1
H), 2.44 and 2.15 (s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3)
δ 196.1, 144.9, 138.8, 137.4, 136.8, 134.7, 133.7, 131.8, 129.9, 129.4,
128.9, 128.2, 126.5, 126.1, 125.2, 17.6, and 16.9. HRMS (EI) m/z
calcd for C19H18OS2Cl [M + H]+: 361.0487; Found: 361.0489.
(E)-2-(Bis(methylthio)methylene)-4-(2-chlorophenyl)-1-henyl-
but-3-en-1-one (3c). 76 mg, 70% yield (eluent: petroleum ether (60−
90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400
MHz, CDCl3) δ 7.96 (d, J = 7.4 Hz, 2 H), 7.64 (d, J = 7.0 Hz, 1 H),
2-Bromo-3,3-bis(methylthio)-1-(o-tolyl)prop-2-en-1-one (1h).
301 mg, 95% yield (eluent: petroleum ether (60−90 °C)/dichloro-
methane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.62
(d, J = 7.7 Hz, 1 H), 7.44 (t, J = 7.4 Hz, 1 H), 7.29 (m, 2 H), 2.64,
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7.58 (m, 2 H), 7.49 (t, J = 7.6 Hz, 2 H), 7.28 (d, J = 8.3 Hz, 1 H),
7.22 (d, J = 7.6 Hz, 1 H), 7.15 (m, 1 H), 6.74 (d, J = 16.5 Hz, 1 H),
2.43 and 2.16 (s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ
196.2, 145.3, 137.5, 136.9, 135.1, 133.8, 133.6, 129.9, 129.5, 129.4,
129.1, 128.9, 127.2, 126.9, 126.7, 17.6, and 16.9. HRMS (EI) m/z
calcd for C19H18OS2Cl [M + H]+: 361.0487; Found: 361.0488.
(E)-2-(Bis(methylthio)methylene)-4-(4-fluorophenyl)-1-phenyl-
but-3-en-1-one (3d). 86 mg, 83% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.97 (m, 2 H), 7.52 (m, 4 H), 7.35 (m, 2 H),
6.97 (m each, 1:1 H), 6.31 (d, J = 16.5 Hz, 1H), 2.43 and 2.13 (s
each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.2, 162.7 (d, J
= 247.0 Hz), 145.3, 136.8, 135.8, 133.6, 133.1 (d, J = 3.4 Hz), 132.2,
129.3, 128.8, 128.4 (d, J = 8.0 Hz), 124.6 (d, J = 2.4 Hz), 115.7 (d, J =
21.7 Hz), 17.5, and 16.7. 19F NMR (400 MHz, CDCl3) δ −113.0.
HRMS (EI) m/z calcd for C19H18OS2F [M + H]+: 345.0783; Found:
345.0785.
CDCl3) δ 7.97 (m, 2 H), 7.57 (m, 2 H), 7.49 (m, 3 H), 7.15 (m, 2
H), 7.07 (d, J = 7.1 Hz, 1 H), 6.58 (d, J = 16.4 Hz, 1 H), 2.43 and
2.11 (s each, 3:3 H), 2.16 (s, 3 H). 13C{1H} NMR (100 MHz,
CDCl3) δ 196.5, 145.9, 136.9, 136.3, 135.9, 135.7, 133.6, 131.5, 130.5,
129.4, 128.8, 128.2, 126.2, 126.0, 125.4, 19.7, 17.5, and 16.8. HRMS
(EI) m/z calcd for C20H21OS2 [M + H]+: 341.1033; Found:
341.1034.
(E)-2-(Bis(methylthio)methylene)-4-(4-methoxyphenyl)-1-phe-
nylbut-3-en-1-one (3k). 87 mg, 81% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.97 (d, J = 7.5 Hz, 2 H), 7.57 (t, J = 7.3 Hz, 1
H), 7.48 (m, 3 H), 7.32 (d, J = 8.7 Hz, 2 H), 6.82 (m each, 1:1 H),
6.30 (d, J = 16.5 Hz, 1 H), 3.79 (s, 3 H), 2.42 and 2.12 (s each, 3:3
H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.5, 160.0, 146.1, 137.0,
133.9, 133.5, 133.3, 129.7, 129.4, 128.8, 128.3, 122.9, 114.2, 55.4,
17.5, and 16.8. HRMS (EI) m/z calcd for C20H21O2S2 [M + H]+:
357.0983; Found: 357.0983.
(E)-2-(Bis(methylthio)methylene)-4-(4-(tert-butyl)phenyl)-1-phe-
nylbut-3-en-1-one (3l). 91 mg, 79% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.96 (m, 2 H), 7.57 (m, 2 H), 7.47 (t, J = 7.6
Hz, 2 H), 7.32 (m each, 2:1 H), 6.33 (d, J = 16.5 Hz, 1 H), 2.43 and
2.13 (s each, 3:3 H) 1.29 (s each, 3:3:3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 196.4, 151.7, 145.9, 136.9, 134.9, 134.1, 133.6, 133.5,
129.4, 128.8, 126.7, 125.7, 124.2, 34.8, 31.3, 17.5, and 16.8. HRMS
(EI) m/z calcd for C23H27OS2 [M + H]+: 383.1503; Found:
383.1504.
(E)-2-(Bis(methylthio)methylene)-1,4-diphenylbut-3-en-1-one
(3m).19a 70 mg, 71% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 8.02 (m, 2 H), 7.64 (m, 2 H), 7.54 (m, 2 H), 7.45 (m, 2
H), 7.32 (m each, 2:1 H), 6.41 (d, J = 16.5 Hz, 1 H), 2.49 and 2.20 (s
each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.3, 145.6,
136.9, 135.7, 133.6, 129.4, 128.9, 128.7, 128.4, 126.9, 124.8, 17.5, and
16.8.
(E)-2-(Bis(methylthio)methylene)-4-(naphthalen-2-yl)-1-phenyl-
but-3-en-1-one (3n). 56 mg, 50% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.98 (m, 2 H), 7.71 (m, 4 H), 7.62 (d, J = 6.9
Hz, 2 H), 7.53 (d, J = 7.4 Hz, 1 H), 7.45 (t, J = 7.5 Hz, 2 H), 7.38 (m
each, 1:1 H), 6.50 (d, J = 16.5 Hz, 1 H), 2.41, and 2.11 (s each, 3:3
H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.3, 145.5, 134.3, 133.6,
133.3, 129.4, 128.8, 128.3, 128.2, 127.7, 127.5, 126.4, 126.3, 125.1,
123.3, 17.5, and 16.8. HRMS (EI) m/z calcd for C23H21OS2 [M +
H]+: 377.1034; Found: 377.1033.
(E)-2-(Bis(methylthio)methylene)-1-(4-bromophenyl)-4-phenyl-
but-3-en-1-one (4a).19a 99 mg, 82% yield (eluent: petroleum ether
(60-90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400
MHz, CDCl3) δ 7.86 (d, J = 8.3 Hz, 2 H), 7.64 (m, 3 H), 7.41 (d, J =
7.3 Hz, 2 H), 7.31 (m, 3 H), 6.35 (d, J = 16.5 Hz, 1 H), 2.46 and 2.18
(s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 195.2, 144.8,
136.7, 136.2, 135.7, 133.6, 132.2, 130.8, 128.8, 128.5, 126.9, 124.6,
17.6, and 16.8.
(E)-2-(Bis(methylthio)methylene)-1-(4-fluorophenyl)-4-phenyl-
but-3-en-1-one (4b). 79 mg, 76% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 8.02 (m, 2 H), 7.64 (d, J = 16.5 Hz, 1 H), 7.41
(d, J = 7.3 Hz, 2 H), 7.31 (m, 3 H), 7.18 (m, 2 H), 6.35 (d, J = 16.6
Hz, 1 H), 2.46 and 2.19 (s each, 3:3 H). 13C{1H} NMR (100 MHz,
CDCl3) δ 194.8, 166.1 (d, J = 254.1 Hz), 145.1, 136.8, 135.9, 133.6,
133.3 (d, J = 2.7 Hz), 132.0 (d, J = 9.4 Hz), 128.8, 128.5, 126.9,
124.7, 116.1 (d, J = 21.8 Hz), 17.6, and 16.8. 19F NMR (400 MHz,
CDCl3) δ −104.2. HRMS (EI) m/z calcd for C19H18OS2F [M + H]+:
345.0783; Found: 345.0783.
(E)-2-(Bis(methylthio)methylene)-1-phenyl-4-(4-
(trifluoromethyl)phenyl)but-3-en-1-one (3e). 88 mg, 74% yield
(eluent: petroleum ether (60−90 °C)/dichloromethane, 3:1, v/v),
1
yellow liquid. H NMR (400 MHz, CDCl3) δ 7.96 (d, J = 7.5 Hz, 2
H), 7.69 (d, J = 16.5 Hz, 1 H), 7.59 (m, 1 H), 7.52 (m, 3 H), 7.47 (m
each, 2:1 H), 6.35 (d, J = 16.5 Hz, 1H), 2.45, and 2.16 (s each, 3:3
H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.0, 144.6, 140.4, 138.4,
136.8, 133.8, 131.6, 129.4, 129.0, 127.0, 126.9, 125.7 (q, J = 3.8 Hz),
17.6, and 16.9. 19F NMR (400 MHz, CDCl3) δ −62.6. HRMS (EI)
m/z calcd for C20H18OS2F3 [M + H]+: 395.0751; Found: 395.0751.
(E)-4-(3-Benzoyl-4,4-bis(methylthio)buta-1,3-dien-1-yl)phenyl
acetate (3f). 82 mg, 71% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.95 (d, J = 7.7 Hz, 2 H), 7.57 (m, 2 H), 7.48 (t, J = 7.5 Hz,
2 H), 7.38 (d, J = 8.4 Hz, 2 H), 7.02 (m each, 1:1 H), 6.32 (d, J =
16.5 Hz, 1 H), 2.42 and 2.13 (s each, 3:3 H), 2.27 (s, 3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 196.2, 169.3, 150.5, 145.2, 136.7, 136.0,
134.6, 133.6, 132.3, 129.3, 128.8, 127.7, 125.0, 121.8, 21.2, 17.4, and
16.7. HRMS (EI) m/z calcd for C21H21O3S2 [M + H]+: 385.0932;
Found: 385.0930.
(E)-4-(3-Benzoyl-4,4-bis(methylthio)buta-1,3-dien-1-yl)-
benzonitrile (3g) and 4-(3-Benzoyl-4,4-bis(methylthio)buta-1,3-
dien-2-yl)benzonitrile (3g′). 72 mg, 68% (3g:3g′ = 7:1) yield
(eluent: petroleum ether (60−90 °C)/dichloromethane, 3:1, v/v),
yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.93 (m, 2 H), 7.90 (m,
0.2 H), 7.71 and 6.30 (d, J = 16.5 Hz, 2 H), 7.57 (m, 3 H), 7.46 (m,
4.6 H), 7.26 and 6.77 (s each, 0.1:0.1 H), 2.46, 2.52, 2.44 and 2.15 (s
each, 0.4:0.4:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 195.8,
144.1, 141.4, 139.8, 136.7, 133.8, 132.4, 131.8, 130.8, 129.3, 128.9,
128.5, 128.0, 127.8, 127.1, 119.0, 111.1, 109.6, 17.6, 17.4, 16.9, and
15.2. HRMS (EI) m/z calcd for C20H18ONS2 [M + H]+: 352.0829;
Found: 352.0831.
(E)-2-(Bis(methylthio)methylene)-1-phenyl-4-(p-tolyl)but-3-en-1-
one (3h). 75 mg, 73% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.96 (m, 2 H), 7.57 (m, 2 H), 7.47 (m, 2 H), 7.28 (d, J =
8.1 Hz, 2 H), 7.09 (m each, 1:1 H), 6.32 (d, J = 16.5 Hz, 1 H), 2.43
and 2.13 (s each, 3:3 H), 2.31 (s, 3 H). 13C{1H} NMR (100 MHz,
CDCl3) δ 196.5, 145.9, 138.5, 136.9, 134.8, 134.1, 133.7, 133.6, 129.5,
129.4, 128.8, 126.8, 123.9, 21.4, 17.5, and 16.8. HRMS (EI) m/z calcd
for C20H21OS2 [M + H]+: 341.1033; Found: 341.1034.
(E)-2-(Bis(methylthio)methylene)-1-phenyl-4-(m-tolyl)but-3-en-
1-one (3i). 77 mg, 75% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.97 (m, 2 H), 7.59 (m, 2 H), 7.48 (t, J = 7.6 Hz, 2 H),
7.19 (m, 3 H), 7.05 (d, J = 6.7 Hz, 1 H), 6.34 (d, J = 16.5 Hz, 1 H),
2.44 and 2.15 (s each, 3:3 H), 2.32 (s, 3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 196.3, 145.7, 138.3, 136.9, 136.8, 135.4, 133.8, 133.5,
129.4, 129.2, 128.8, 128.6, 127.6, 124.6, 124.0, 21.4, 17.5, and 16.8.
HRMS (EI) m/z calcd for C20H21OS2 [M + H]+: 341.1033; Found:
341.1034.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(4-
(trifluoromethyl)phenyl)but-3-en-1-one (4c). 93 mg, 79% yield
(eluent: petroleum ether (60−90 °C)/dichloromethane, 3:1, v/v),
1
yellow liquid. H NMR (400 MHz, CDCl3) δ 8.09 (d, J = 8.0 Hz, 2
(E)-2-(Bis(methylthio)methylene)-1-phenyl-4-(o-tolyl)but-3-en-1-
one (3j). 69 mg, 68% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
H), 7.77 (d, J = 8.1 Hz, 2 H), 7.63 and 6.34 (d, J = 16.5 Hz, 2 H),
7.41 (d, J = 7.3 Hz, 2 H), 7.31 (m, 3 H), 2.46 and 2.16 (s each, 3:3
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H). 13C{1H} NMR (100 MHz, CDCl3) δ 195.1, 144.6, 139.7, 136.6
(d, J = 4.3 Hz), 134.7 (d, J = 32.2 Hz), 133.7, 129.6, 128.8, 128.6,
126.9, 126.0 (q, J = 3.3 Hz), 124.5, 17.6, and 16.8. 19F NMR (400
MHz, CDCl3) δ −63.1. HRMS (EI) m/z calcd for C20H18OS2F3 [M +
H]+: 395.0751; Found: 395.0752.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(3-
(trifluoromethyl)phenyl)but-3-en-1-one (4d). 73 mg, 62% yield
(eluent: petroleum ether (60−90 °C)/dichloromethane, 3:1, v/v),
yellow liquid. 1H NMR (400 MHz, CDCl3) δ 8.27 (s, 1 H), 8.13 (d, J
= 7.8 Hz, 1 H), 7.85 (d, J = 7.6 Hz, 1 H), 7.64 (m 2 H), 7.42 (d, J =
7.3 Hz, 2 H), 7.31 (m, 3 H), 6.35 (d, J = 16.5 Hz, 1 H), 2.46 and 2.15
(s each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 194.8, 144.4,
137.1 (d, J = 88.9 Hz), 136.8, 133.7, 132.5, 131.6 (d, J = 32.8 Hz),
129.9 (q, J = 3.6 Hz), 129.6, 128.8, 128.7, 128.6, 127.9, 126.9, 125.9
(q, J = 4.0 Hz), 124.5, 17.5, and 16.8. 19F NMR (400 MHz, CDCl3) δ
−62.7. HRMS (EI) m/z calcd for C20H18OS2F3 [M + H]+: 395.0751;
Found: 395.0751.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(p-tolyl)but-3-en-1-
one (4e).19a 81 mg, 79% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.94 (d, J = 8.0 Hz, 2 H), 7.69 and 6.41 (d, J = 16.5 Hz, 2
H), 7.44 (d, J = 7.4 Hz, 2 H), 7.34 (m, 4 H), 7.29 (d, J = 7.1 Hz, 1
H), 2.49 (s each, 3:3 H), and 2.22 (s, 3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 196.0, 145.7, 144.6, 136.9, 135.4, 134.3, 133.4, 129.6,
128.7, 128.3, 126.8, 124.9, 21.9, 17.5, and 16.8.
(E)-2-(Bis(methylthio)methylene)-1-(naphthalen-2-yl)-4-phenyl-
but-3-en-1-one (4k). 54 mg, 48% yield (eluent: petroleum ether (60-
90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400
MHz, CDCl3) δ 8.52 (s, 1 H), 8.19 (dd, J = 8.6, 1.5 Hz, 1 H), 8.02 (t,
J = 6.9 Hz, 2 H), 7.95 (d, J = 8.1 Hz, 1 H), 7.79 and 6.49 (d, J = 16.5
Hz, 2 H), 7.66 (m, 1 H), 7.60 (m, 1 H), 7.46 (d, J = 7.4 Hz, 2 H),
7.32 (m, 3 H), 2.53 and 2.19 (s each, 3:3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 196.3, 145.6, 136.8, 136.0, 135.9, 134.3, 133.6, 132.7,
131.4, 129.8, 128.8, 128.7, 128.3, 127.9, 126.9, 126.8, 124.9, 124.6,
17.5, and 16.8. HRMS (EI) m/z calcd for C23H21OS2 [M + H]+:
377.1033; Found: 377.1034.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(thiophen-2-yl)but-
3-en-1-on (4l). 65 mg, 65% yield (eluent: petroleum ether (60−90
1
°C)/dichloromethane, 3:1, v/v), yellow liquid. H NMR (400 MHz,
CDCl3) δ 7.69 (dd, J = 4.9, 1.2 Hz, 1 H), 7.62 (dd, J = 3.8, 1.1 Hz, 1
H), 7.57 and 6.45 (d, J = 16.5 Hz, 2 H), 7.40 (m, 2 H), 7.29 (m, 2 H),
7.23 (m, 1 H), 7.12 (m, 1 H), 2.43 and 2.22 (s each, 3:3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 188.6, 145.2, 144.4, 136.8, 136.7, 134.7,
134.1, 133.5, 128.7, 128.4, 126.9, 124.5, 17.8, and 16.9. HRMS (EI)
m/z calcd for C17H17OS3 [M + H]+: 333.0441; Found: 333.0442.
(E)-4-(Bis(methylthio)methylene)-2,2-dimethyl-6-phenylhex-5-
en-3-one (4m). 54 mg, 59% yield (eluent: petroleum ether (60−90
1
°C)/dichloromethane, 3:1, v/v), yellow liquid. H NMR (400 MHz,
CDCl3) δ 7.43 (m each, 2:1 H), 7.33 (m, 2 H), 7.26 (m, 1 H), 6.33
(d, J = 16.6 Hz, 1 H), 2.36 and 2.32 (s each, 3:3 H), and 1.29 (s each,
3:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 213.9, 147.8, 136.8,
133.4, 133.0, 128.8, 128.4, 126.9, 124.1, 44.3, 28.5, 17.6, and 16.9.
HRMS (EI) m/z calcd for C17H23OS2 [M + H]+: 307.1190; Found:
307.1190.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(m-tolyl)but-3-en-
1
1-one (4f). 72 mg, 70% yield, yellow liquid. H NMR (400 MHz,
CDCl3) δ 7.88 (s, 1 H), 7.78 (d, J = 7.2 Hz, 1 H), 7.68 and 6.41 (d, J
= 16.5 Hz, 2 H), 7.45 (d, J = 7.2 Hz, 3 H), 7.31 (m, 4 H), 2.49 (s
each, 3:3 H), and 2.20 (s, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ
196.5, 145.7, 138.7, 136.9, 136.8, 135.5, 134.5, 133.5, 129.6, 128.7,
128.3, 126.9, 124.8, 21.5, 17.5, and 16.8. HRMS (EI) m/z calcd for
C20H21OS2 [M + H]+: 341.1033; Found: 341.1034.
(E)-2-(Bis(methylthio)methylene)-4-phenyl-1-(o-tolyl)but-3-en-1-
one (4g). 52 mg, 51% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.69 (m, 2 H), 7.47 (m, 3 H), 7.38 (m, 3 H), 7.30 (m each,
1:1 H), 6.57 (d, J = 16.5 Hz, 1 H), 2.80 (s, 3 H), 2.47 and 2.03 (s
each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 198.0, 147.6,
140.6, 137.1, 137.0, 136.2, 133.6, 132.1, 131.1, 128.7, 128.3, 126.9,
125.6, 125.4, 21.9, 17.1, and 16.8. HRMS (EI) m/z calcd for
C20H21OS2 [M + H]+: 341.1033; Found: 341.1034.
(E)-3-(1,3-Dithiolan-2-ylidene)-5-phenylpent-4-en-2-one (4o).17b
50 mg, 63% yield (eluent: petroleum ether (60−90 °C)/dichloro-
methane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.47
(m, 2 H), 7.36 (m, 2 H), 7.29 (m, 1 H), 6.99 (d, J = 16.2 Hz, 1 H),
6.69 (d, J = 16.2 Hz, 1 H), 3.43 and 3.29 (m each, 2:2 H), and 2.33
(s, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 194.0, 162.9, 137.0,
134.3, 128.8, 128.1, 126.5, 124.2, 39.4, 35.6, and 28.6.
(E)-2-(1,3-Dithiolan-2-ylidene)-1,4-diphenylbut-3-en-1-one
(4p).25 69 mg, 71% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.82 (m, 2 H), 7.48 (m, 1 H), 7.39 (m, 2 H), 7.26 (m, 4
H), 7.18 (m, 1 H), 7.03 and 6.26 (d, J = 16.2 Hz, 2 H), and 3.41 (m
each, 2:2 H). 13C{1H} NMR (100 MHz, CDCl3) δ 194.0, 154.8,
137.9, 137.3, 132.4, 131.2, 129.8, 128.7, 128.4, 127.6, 126.7, 126.3,
125.1, 38.7, and 37.0.
(E)-2-(Bis(ethylthio)methylene)-1,4-diphenylbut-3-en-1-one (4q).
79 mg, 74% yield (eluent: petroleum ether (60−90 °C)/dichloro-
methane, 3:1, v/v), yellow liquid. 1H NMR (400 MHz, CDCl3) δ 7.96
(m, 2 H), 7.71 and 6.35 (d, J = 16.5 Hz, 2 H), 7.56 (m, 1 H), 7.45 (m,
2 H), 7.38 (m, 2 H), 7.29 (m, 2 H), 7.22 (m, 1 H), 2.90 and 2.69 (m
each, 2:2 H), 1.35 and 1.02 (s each, 3:3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 196.7, 148.0, 136.9, 133.5, 133.4, 133.1, 129.5, 128.8,
128.7, 128.3, 126.9, 125.1, 28.5, 28.0, 15.4, and 14.6. HRMS (EI) m/z
calcd for C21H23OS2 [M + H]+: 355.1190; Found: 355.1190.
(E)-2-(Bis(methylthio)methylene)-4-(m-tolyl)-1-(p-tolyl)but-3-en-
1-one (4r). 73 mg, 69% yield (eluent: petroleum ether (60−90 °C)/
dichloromethane, 1:1, v/v), yellow liquid. 1H NMR (400 MHz,
CDCl3) δ 7.98 (d, J = 8.0 Hz, 2 H), 7.71 and 6.42 (d, J = 16.5 Hz, 2
H), 7.38 (d, J = 7.9 Hz, 2 H), 7.28 (m, 3 H), 7.15 (d, J = 6.2 Hz, 1
H), 2.53 (s each, 3:3 H), 2.42 (s, 3 H), and 2.27 (s, 3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 196.1, 145.9, 144.5, 138.2, 136.8, 135.0,
134.4, 133.7, 129.6, 129.2, 128.6, 127.6, 124.7, 124.0, 21.9, 21.4, 17.6,
and 16.8. HRMS (EI) m/z calcd for C21H23OS2 [M + H]+: 355.1190;
Found: 355.1190.
(E)-2-(Bis(methylthio)methylene)-1-(4-ethylphenyl)-4-phenylbut-
3-en-1-one (4h). 69 mg, 65% yield (eluent: petroleum ether (60−90
1
°C)/dichloromethane, 3:1, v/v), yellow liquid. H NMR (400 MHz,
CDCl3) δ 7.95 (d, J = 7.9 Hz, 2 H), 7.68 and 6.40 (d, J = 16.5 Hz, 2
H), 7.44 (d, J = 7.3 Hz, 2 H), 7.35 (m, 4 H), 7.29 (d, J = 7.1 Hz, 1
H), 2.78 (m, 2 H), 2.49 and 2.23 (s each, 3:3 H), 1.33 (t, J = 7.4 Hz,
3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.0, 150.6, 145.7, 136.8,
135.3, 134.5, 133.4, 129.6, 128.6, 128.4, 128.2, 126.8, 124.8, 29.1,
17.5, 16.8, and 15.1. HRMS (EI) m/z calcd for C21H23OS2 [M + H]+:
355.1190; Found: 355.1190.
(E)-2-(Bis(methylthio)methylene)-1-(4-methoxyphenyl)-4-phe-
nylbut-3-en-1-one (4i).19a 78 mg, 73% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 8.01 (d, J = 8.4 Hz, 2 H), 7.69 and 6.41 (d, J =
16.5 Hz, 2 H), 7.45 (d, J = 7.6 Hz, 2 H), 7.32 (m, 3 H), 7.02 (d, J =
8.4 Hz, 2 H), 3.93 (s, 3 H), 2.49 and 2.25 (s each, 3:3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 195.1, 164.0, 145.7, 136.9, 135.2, 133.4,
131.8, 129.8, 128.7, 128.3, 126.8, 124.9, 114.1, 55.6, 17.6, and 16.8.
(E)-2-(Bis(methylthio)methylene)-1-(2-methoxyphenyl)-4-phe-
nylbut-3-en-1-one (4j). 46 mg, 43% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 3:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.95 (d, J = 7.6 Hz, 1 H), 7.63 and 6.49 (d, J =
16.5 Hz, 2 H), 7.56 (m, 1 H), 7.47 (d, J = 7.4 Hz, 2 H), 7.35 (m, 2
H), 7.28 (m, 1 H), 7.07 (m, 2 H), 3.92 (s, 3 H), 2.46 and 2.14 (s
each, 3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 194.8, 159.8,
148.5, 137.2, 134.6, 134.0, 132.7, 132.3, 128.6, 128.1, 126.8, 125.0,
120.5, 112.3, 55.9, 17.2, and 16.8. HRMS (EI) m/z calcd for
C20H21O2S2 [M + H]+: 357.0983; Found: 357.0983.
(E)-2-(Bis(methylthio)methylene)-4-(4-chlorophenyl)-1-(p-tolyl)-
but-3-en-1-one (4s). 80 mg, 71% yield (eluent: petroleum ether (60−
90 °C)/dichloromethane, 1:1, v/v), yellow liquid. 1H NMR (400
MHz, CDCl3) δ 7.88 (d, J = 7.7 Hz, 2 H), 7.60 and 6.30 (d, J = 16.5
Hz, 2 H), 7.27 (m, 6 H), 2.44 (s each, 3:3 H), and 2.17 (s, 3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 195.8, 145.2, 144.7, 136.3,
135.4, 134.2, 133.8, 131.9, 129.6, 129.5, 128.8, 128.0, 125.4, 21.9,
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17.5, and 16.8. HRMS (EI) m/z calcd for C20H20OS2Cl [M + H]+:
375.0644; Found: 375.0644.
mmol), 1-methoxy-4-vinylbenzene (2k) (27 mg, 0.2 mmol), Pd-
(OAc)2 (5 mg, 0.024 mmol), XantPhos (46 mg, 0.08 mmol), and
Cs2CO3 (287 mg, 0.88 mmol) in 4 mL of benzene was stirred at
ambient temperature under visible-light irradiation of a 15 W blue
LED bulb for 4 h. The corresponding products of 3e (11 mg, 14%)
and 3k (22 mg, 31%) were isolated by column chromatography on
silica gel (60−120 mesh) using petroleum ether (60-90 °C)/
dichloromethane (1:1, v/v) as the eluent. In a similar fashion,
products of 4c (28 mg, 35%) and 4e (18 mg, 27%) were generated
from the competition reaction of 1d, 1f, and 2m in a molar ratio of
1:1:3 under visible-light irradiation of a 15 W blue LED bulb for 4 h.
Derivatization of 1,3-Dienes 3 and 4. A Typical Procedure for
the Derivatization of 3 or 4 to Furans: Synthesis of (2-(Methylthio)-
5-phenylfuran-3-yl)(p-tolyl)methanone (6a).19a A mixture of 4e (68
mg, 0.2 mmol) and NBS (53 mg, 0.3 mmol) in 1 mL of CH3CN/H2O
(50:1, v/v) was stirred at 25 °C for 24 h. The reaction mixture was
poured into ice-cold water (100 g) and extracted with dichloro-
methane (20 mL). The organic layer was separated and dried over
anhydrous sodium sulfate. All the volatiles were removed under
reduced pressure, and the residue was purified by column
chromatography on silica gel (60−120 mesh) using petroleum ether
(60−90 °C)/dichloromethane (1:1, v/v) as the eluent to give 6a as a
(E)-2-(Bis(methylthio)methylene)-4-(4-(tert-butyl)phenyl)-1-(p-
tolyl)but-3-en-1-one (4t). 89 mg, 75% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 1:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.92 (d, J = 7.8 Hz, 2 H), 7.64 and 6.39 (d, J =
16.5 Hz, 2 H), 7.33 (m, 6 H), 2.46 (s each, 3:3 H), 2.20 (s, 3 H), and
1.34 (s each, 3:3:3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.0,
151.5, 146.0, 144.4, 134.5, 134.3, 134.1, 133.4, 129.5, 126.6, 125.6,
124.1, 34.7, 31.3, 21.8, 17.5, and 16.7. HRMS (EI) m/z calcd for
C24H29OS2 [M + H]+: 397.1659; Found: 397.1660.
(E)-2-(Bis(methylthio)methylene)-4-(4-chlorophenyl)-1-(4-
ethylphenyl)but-3-en-1-one (4u). 79 mg, 68% yield (eluent:
petroleum ether (60−90 °C)/dichloromethane, 1:1, v/v), yellow
liquid. 1H NMR (400 MHz, CDCl3) δ 7.90 (d, J = 8.0 Hz, 2 H), 7.61
and 6.30 (d, J = 16.5 Hz, 2 H), 7.31 (m, 4 H), 7.25 (d, J = 8.4 Hz, 2
H), 2.73 (m, 2 H), 2.44 and 2.17 (s each, 3:3 H), and 1.28 (t, J = 7.6
Hz, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 195.9, 150.7, 145.2,
136.2, 135.4, 134.4, 133.8, 131.9, 129.6, 128.8, 128.4, 128.0, 125.3,
29.1, 17.5, 16.8, and 15.1. HRMS (EI) m/z calcd for C21H22OS2Cl
[M + H]+: 389.0800; Found: 389.0801.
(E)-2-(Bis(methylthio)methylene)-4-(4-(tert-butyl)phenyl)-1-(4-
ethylphenyl)but-3-en-1-one (4v). 86 mg, 70% yield (eluent:
petroleum ether (60−90 °C)/dichloromethane, 1:1, v/v), yellow
liquid. 1H NMR (400 MHz, CDCl3) δ 7.88 (d, J = 8.2 Hz, 2 H), 7.58
and 6.33 (d, J = 16.5 Hz, 2 H), 7.30 (m, 6 H), 2.72 (m, 2 H), 2.43
and 2.16 (s each, 3:3 H), 1.29 (s each, 3:3:3 H), 1.27 (t, J = 7.6 Hz, 3
H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.0, 151.5, 150.5, 146.0,
134.5, 134.1, 133.4, 129.6, 129.5, 128.3, 126.6, 125.6, 124.1, 34.7,
31.3, 29.1, 17.5, 16.8, and 15.1. HRMS (EI) m/z calcd for C25H31OS2
[M + H]+: 411.1816; Found: 411.1816.
(E)-2-(Bis(methylthio)methylene)-4-(naphthalen-2-yl)-1-(p-tolyl)-
but-3-en-1-one (4w). 61 mg, 52% yield (eluent: petroleum ether
(60−90 °C)/dichloromethane, 1:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.93 (d, J = 8.0 Hz, 2 H), 7.76 (m each, 3:1 H),
7.67 (m, 2 H), 7.43 (m, 2 H), 7.30 (d, J = 7.9 Hz, 2 H), 6.53 (d, J =
16.5 Hz, 1 H), 2.45 (s each, 3:3 H), and 2.19 (s, 3 H). 13C{1H} NMR
(100 MHz, CDCl3) δ 196.1, 145.8, 144.6, 135.5, 134.4, 134.3, 133.6,
133.5, 133.3, 129.6, 128.3, 128.2, 127.7, 127.5, 126.4, 126.3, 125.1,
123.3, 21.9, 17.6, and 16.8. HRMS (EI) m/z calcd for C24H23OS2 [M
+ H]+: 391.1190; Found: 391.1190.
(E)-2-(Bis(methylthio)methylene)-1-(4-ethylphenyl)-4-(naphtha-
len-2-yl)but-3-en-1-one (4x). 75 mg, 62% yield (eluent: petroleum
ether (60-90 °C)/dichloromethane, 1:1, v/v), yellow liquid. 1H NMR
(400 MHz, CDCl3) δ 7.95 (d, J = 8.1 Hz, 2 H), 7.76 (m each, 3:1 H),
7.67 (m, 2 H), 7.42 (m, 2 H), 7.33 (d, J = 8.1 Hz, 2 H), 6.53 (d, J =
16.5 Hz, 1 H), 2.73 (m, 2 H), 2.46 and 2.19 (s each, 3:3 H), and 1.28
(t, J = 7.6 Hz, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 196.1,
150.7, 145.7, 135.4, 134.5, 134.4, 133.5, 133.5, 133.3, 129.6, 128.4,
128.3, 128.1, 127.7, 127.5, 126.4, 126.2, 125.1, 123.3, 29.1, 17.6, 16.8,
and 15.1. HRMS (EI) m/z calcd for C25H25OS2 [M + H]+: 405.1346;
Found: 405.1347.
A Procedure for Gram-Scale Preparation of 3a. A mixture of
2-bromo-3,3-bis(methylthio)-1-phenylprop-2-en-1-one (1a) (1.52 g,
5 mmol), 4-chlorostyrene (2a) (1.04 g, 7.5 mmol), Pd(OAc)2 (67
mg, 0.3 mmol), XantPhos (579 mg, 1 mmol), and Cs2CO3 (3.6 g, 11
mmol) in 50 mL of benzene was stirred at ambient temperature under
visible-light irradiation of a 15 W blue LED bulb (450−460 nm) for
24 h. After complete consumption of 1a by TLC monitoring on silica
gel, EtOAc (50 mL) and brine (50 mL) were successively added. The
organic phase was separated, and the aqueous phase was extracted
with EtOAc (3 × 15 mL). The combined organic phase was washed
with water (3 × 15 mL), dried over anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The resultant residue was
subjected to purification by column chromatography on silica gel
(eluent: petroleum ether (60−90 °C)/dichloromethane = 20:1, v/v)
to afford 3a as a yellow liquid (1.17 g, 65%).
1
white solid (43 mg, 70%), mp: 64−65 °C. H NMR (400 MHz,
CDCl3) δ 7.73 (d, J = 8.0 Hz, 2 H), 7.52 (d, J = 7.3 Hz, 2 H), 7.45 (s,
1 H), 7.37 (t, J = 7.5 Hz, 2 H), 7.29 (m each, 2:1 H), 2.65 (s, 3 H),
and 2.44 (s, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 190.0, 152.0,
142.8, 140.4, 136.6, 135.9, 133.5, 129.5, 129.2, 127.9, 125.9, 125.5,
21.8, and 19.2.
(5-(4-Chlorophenyl)-2-(methylthio)furan-3-yl)(p-tolyl)-
methanone (6b). 43 mg, 63% yield (eluent: petroleum ether (60−90
°C)/dichloromethane, 1:1, v/v), white solid, mp: 89−90 °C. 1H
NMR (400 MHz, CDCl3) δ 7.69 (d, J = 7.5 Hz, 2 H), 7.41 (d, J = 8.2
Hz, 3 H), 7.29 (m each, 3:1 H), 2.62 (s, 3 H), and 2.42 (s, 3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 189.8, 152.5, 142.9, 138.9,
136.5, 135.8, 133.6, 132.0, 129.4, 129.3, 129.2, 126.6, 126.2, 21.8, and
19.2. HRMS (EI) m/z calcd for C19H16O2SCl [M + H]+: 343.0560;
Found: 343.0559.
(5-(4-(tert-Butyl)phenyl)-2-(methylthio)furan-3-yl)(p-tolyl)-
methanone (6c). 47 mg, 65% yield (eluent: petroleum ether (60−90
°C)/dichloromethane, 1:1, v/v), white solid, mp: 75−76 °C. 1H
NMR (400 MHz, CDCl3) δ 7.77 (d, J = 7.9 Hz, 2 H), 7.57 (d, J = 8.3
Hz, 2 H), 7.43 (d, J = 8.4 Hz, 2 H), 7.30 (d, J = 7.8 Hz, 2 H), 6.90 (s,
1 H), 2.68 (s, 3 H), 2.44 (s, 3 H), and 1.34 (s each, 3:3:3 H).
13C{1H} NMR (100 MHz, CDCl3) δ 189.2, 157.2, 154.4, 151.3,
142.9, 136.4, 129.2, 129.1, 127.2, 125.9, 123.5, 123.3, 106.7, 34.8,
31.4, 21.8, and 14.3. HRMS (EI) m/z calcd for C23H25O2S [M + H]+:
365.1575; Found: 365.1575.
(2-(Methylthio)-5-(m-tolyl)furan-3-yl)(p-tolyl)methanone (6d).
45 mg, 70% yield (eluent: petroleum ether (60−90 °C)/dichloro-
methane, 1:1, v/v), white solid, mp: 68−69 °C. 1H NMR (400 MHz,
CDCl3) δ 7.77 (d, J = 8.0 Hz, 2 H), 7.43 (s, 2 H), 7.29 (m, 3 H), 7.11
(d, J = 7.5 Hz, 1 H), 6.93 (s, 1 H), 2.69 (s, 3 H), 2.44 (s, 3 H), and
2.40 (s, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 189.1, 157.5,
154.3, 142.9, 138.7, 136.3, 129.8, 129.2, 129.1, 128.9, 124.2, 123.2,
120.8, 107.3, 21.8, 21.6, and 14.3. HRMS (EI) m/z calcd for
C20H19O2S [M + H]+: 323.1105; Found: 323.1106.
(4-Methoxyphenyl)(2-(methylthio)-5-phenylfuran-3-yl)-
methanone (6e).19a 46 mg, 71% yield (eluent: petroleum ether (60−
90 °C)/dichloromethane, 1:1, v/v), white solid, mp: 109−110 °C. 1H
NMR (400 MHz, CDCl3) δ 7.84 (d, J = 8.8 Hz, 2 H), 7.53 (d, J = 7.4
Hz, 2 H), 7.45 (s, 1 H), 7.38 (t, J = 7.5 Hz, 2 H), 7.30 (t, J = 7.4 Hz, 1
H), 6.98 (m each, 1:1 H), 3.89 (s, 3 H), and 2.64 (s, 3 H). 13C{1H}
NMR (100 MHz, CDCl3) δ 189.1, 163.0, 150.7, 140.8, 136.5, 133.5,
131.8, 131.7, 129.2, 128.0, 125.7, 125.5, 113.8, 55.6, and 19.4.
(5-(4-Chlorophenyl)-2-(methylthio)furan-3-yl)(4-ethylphenyl)-
methanone (6f). 47 mg, 66% yield (eluent: petroleum ether (60−90
°C)/dichloromethane, 1:1, v/v), white solid, mp: 83−84 °C. 1H
NMR (400 MHz, CDCl3) δ 7.74 (d, J = 8.1 Hz, 2 H), 7.44 (m each,
2:1 H), 7.32 (m, 4 H), 2.74 (m, 2 H), 2.64 (s, 3 H), and 1.30 (t, J =
7.6 Hz, 3 H). 13C{1H} NMR (100 MHz, CDCl3) δ 189.8, 152.6,
Control Experiments. Under an N2 atmosphere, a mixture of 2-
bromo-3,3-bis(methylthio)-1-phenylprop-2-en-1-one (1a) (182 mg,
0.6 mmol), 1-(trifluoromethyl)-4-vinylbenzene (2e) (34 mg, 0.2
8410
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149.1, 138.9, 136.7, 135.8, 133.7, 132.0, 129.5, 129.3, 128.0, 126.7,
126.3, 29.1, 19.2, and 15.4. HRMS (EI) m/z calcd for C20H18O2SCl
[M + H]+: 357.0716; Found: 357.0716.
of Chinese Academy of Sciences, Beijing 100049, P. R.
China; orcid.org/0000-0001-5350-8308
Yuan He − Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, P. R. China; University
of Chinese Academy of Sciences, Beijing 100049, P. R.
China; orcid.org/0000-0001-6600-8433
Bao-Hua Xu − Innovation Academy for Green Manufacture,
Chinese Academy of Sciences, Beijing 100190, P. R. China;
orcid.org/0000-0002-7222-4383
(5-(4-(tert-Butyl)phenyl)-2-(methylthio)furan-3-yl)(4-
ethylphenyl)methanone (6g). 54 mg, 71% yield (eluent: petroleum
ether (60−90 °C)/dichloromethane, 1:1, v/v), white solid, mp: 78−
79 °C. 1H NMR (400 MHz, CDCl3) δ 7.75 (d, J = 8.2 Hz, 2 H), 7.43
(m each, 4:1 H), 7.30 (d, J = 8.0 Hz, 2 H), 2.74 (m, 2 H), 2.65 (s, 3
H), 1.33 (s, 9 H), and 1.30 (t, J = 7.6 Hz, 3 H). 13C{1H} NMR (100
MHz, CDCl3) δ 190.0, 151.5, 151.2, 149.0, 140.5, 136.9, 135.8, 130.7,
129.6, 128.0, 126.1, 125.6, 125.3, 34.8, 31.4, 29.1, 19.2, and 15.4.
HRMS (EI) m/z calcd for C24H27O2S [M + H]+: 379.1731; Found:
379.1732.
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.1c00838
(4-Ethylphenyl)(2-(methylthio)-5-(naphthalen-2-yl)furan-3-yl)-
methanone (6h). 51 mg, 69% yield (eluent: petroleum ether (60−90
°C)/dichloromethane, 1:1, v/v), white solid, mp: 74−75 °C. 1H
NMR (400 MHz, CDCl3) δ 7.95 (s, 1 H), 7.80 (m, 5 H), 7.64 (m, 1
H), 7.59 (s, 1 H), 7.54 (m, 1 H), 7.48 (m, 1 H), 7.32 (m, 2 H), 2.75
(m, 2 H), 2.68 (s, 3 H), and 1.31 (t, J = 7.6 Hz, 3 H). 13C{1H} NMR
(100 MHz, CDCl3) δ 189.9, 152.5, 149.0, 140.4, 136.8, 133.7, 132.9,
131.6, 129.6, 129.5, 128.9, 128.0, 127.9, 126.9, 126.3, 123.9, 123.6,
29.1, 19.2, and 15.4. HRMS (EI) m/z calcd for C24H21O2S [M + H]+:
373.1262; Found: 373.1262.
Author Contributions
#Y.L.L. and H.B.L. contributed equally to this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We are grateful to the National Natural Science Foundation of
China (21871253 and 21672209).
■
Radical-Trapping Experiments. Under an N2 atmosphere, a
mixture of 2-bromo-3,3-bis(methylthio)-1-phenylprop-2-en-1-one
(1a) (91 mg, 0.3 mmol), styrene (2m) (47 mg, 0.45 mmol),
Pd(OAc)2 (4 mg, 0.018 mmol), XantPhos (35 mg, 0.06 mmol),
Cs2CO3 (215 mg, 0.66 mmol), and 2,2,6,6-tetramethyl-1-piperidyloxy
(TEMPO) (164 mg, 1.05 mmol) or 2,6-di-tert-butyl-4-methylphenol
(BHT) (231 mg, 1.05 mmol) or PhNO2 (129 mg, 1.05 mmol) in 3
mL of benzene was stirred at ambient temperature under visible-light
irradiation of a 15 W blue LED bulb for 12 h. No target product 3m
was detected by GC and proton NMR analyses of the resultant
reaction mixture. However, species 7 was detected in the reaction
mixture by HRMS determinations.
DEDICATION
Dedicated to Professor Christian Bruneau.
■
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.1c00838.
■
sı
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AUTHOR INFORMATION
Corresponding Authors
■
Zhengkun Yu − Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, P. R. China;
Innovation Academy for Green Manufacture, Chinese
Academy of Sciences, Beijing 100190, P. R. China; State Key
Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences,
Shanghai 200032, P. R. China; orcid.org/0000-0002-
9908-0017; Email: zkyu@dicp.ac.cn
Hongmei Wang − State Key Laboratory of NBC Protection
for Civilian, Beijing 102205, P. R. China; orcid.org/
0000-0003-1057-334X; Email: wanghongmei@dicp.ac.cn
Authors
Yunlong Li − Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, P. R. China; University
of Chinese Academy of Sciences, Beijing 100049, P. R.
China; orcid.org/0000-0003-1516-2806
Haibo Liu − State Key Laboratory of NBC Protection for
Civilian, Beijing 102205, P. R. China
Zilong Huang − Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, P. R. China; University
8411
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