Palladium-Catalyzed Intramolecular Allylic Amidation via Decarboxylative Aromatization: Synthesis of N-Allyl-N-aryl Sulfonamides

Article abstract of DOI:10.1021/acs.joc.1c01065

A protocol in the preparation of functionalizedN-allyl-N-aryl sulfonamides via palladium-catalyzed intramolecular decarboxylative N-allylation reaction is presented. The alkylated 2,5-cyclohexadienyl ketoesters reacted with arylsulfonamides in the presence of titanium tetrachloride and pyridine, which allows the formation of alkylated 2,5-cyclohexadienyl sulfonyl iminoesters which then undergo a palladium-catalyzed intramolecular allylic amidation through decarboxylative aromatization to provide functionalizedN-allyl-N-aryl sulfonamides. This allylation protocol proceeds with good regioselectivity. Moreover, we have also shown thatN-allyl-N-aryl sulfonamide can be transformed into 4-aryl-1,2,3,4-tetrahydroquinoline and nitrogen-containing β-hydroxysulfide bioactives.

Full text of DOI:10.1021/acs.joc.1c01065

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Article
Palladium-Catalyzed Intramolecular Allylic Amidation via
Decarboxylative Aromatization: Synthesis of N‑Allyl‑N‑aryl
Sulfonamides
Tzu-Lun Liu, Meng-Li Jhou, Cheng-En Hsieh, Chia-Jung Lin, Hsiu-Hui Su, and Chih-Ming Chou*
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ABSTRACT: A protocol in the preparation of functionalized N-
allyl-N-aryl sulfonamides via palladium-catalyzed intramolecular
decarboxylative N-allylation reaction is presented. The alkylated
2,5-cyclohexadienyl ketoesters reacted with arylsulfonamides in the
presence of titanium tetrachloride and pyridine, which allows the
formation of alkylated 2,5-cyclohexadienyl sulfonyl iminoesters
which then undergo a palladium-catalyzed intramolecular allylic
amidation through decarboxylative aromatization to provide
functionalized N-allyl-N-aryl sulfonamides. This allylation protocol
proceeds with good regioselectivity. Moreover, we have also shown
that N-allyl-N-aryl sulfonamide can be transformed into 4-aryl-
1,2,3,4-tetrahydroquinoline and nitrogen-containing β-hydroxysul-
fide bioactives.
of allylic N-tosylcarbamates via base-induced aza-Claisen
rearrangement14 or allylic substitution15 has been developed.
Furthermore, intermolecular allylic amidation of β,γ-unsatu-
rated carboxylic acids or α,α-disubstituted alkenes mediated by
metal catalysis,16 hypervalent iodine(III) reagents,17 or NBS-
(P)/DBU combination strategy18 have also been reported
(Scheme 2b).
Transition metal-catalyzed intramolecular decarboxylative
allylations are represented as a powerful strategy for the
formation of carbon−carbon and carbon−heteroatom bonds.19
Recently, we reported a palladium-catalyzed decarboxylative
allylic etherification of cross-conjugated ketoesters in prepara-
tion of functionalized allyl aryl ethers via a resonance-stabilized
aryl oxide intermediate.20 Along this line, we envision that the
strategy of C−O bond formation can be extended to C−N
bond formation using cross-conjugated sulfonyl iminoesters.
We assume that intramolecular decarboxylative N-allylation
will also proceed via a stable amide anion intermediate. This
amide anion can further undergo nucleophilic addition to the
Pd-π-allyl electrophile to eventually realize C−N bond
formation. As a result, various functionalized N-allyl-N-aryl
sulfonamides can be readily synthesized (Scheme 2c). Herein,
INTRODUCTION
■
Sulfonamides, since they were discovered as an antibacterial in
1932, have found widespread indications such as Alzheimer’s
disease and other central nervous system disorders, diabetes,
and various cancers.1 Bioisosteric replacement of the keto
group in benzophenone by sulfonamide leads to development
of a new series of N-phenylbenzenesulfonamide.2 Sulfonamide
analogues designed as anticancer agents were able to enhance
sensitivity to radiation therapy.3 N-Substituted biphenyl bis-
sulfonamides have been shown to elicit anti Alzheimer activity
by inhibiting acetyl- and butyrylcholinesterase.4 Very recently,
N-substituted sulfonamides were effective against dengue and
Ebola virus infection (Scheme 1).5
Over the past decades, great efforts have been made in
preparation of N-functionalized sulfonamides.6 Among them,
one of the most common methods to achieve N-aryl
sulfonamides is the palladium- or copper-catalyzed cross-
coupling reaction of primary sulfonamides with aryl halides,7
pseudohalides,8 arylboronic acids,9 or sodium arylsulfinates.10
Rhodium-catalyzed N-chelator-directed ortho C−H bond
amidation of arenes with sulfonamides has recently been
developed.11 Moreover, a transition-metal-free procedure for
N-arylation of sulfonamides by reaction with o-silylaryl triflates
in the presence of cesium fluoride has also been reported
(Scheme 2a).12 For the synthesis of N-allyl sulfonamides, Cui
and Yomamoto have reported the gold- or palladium-catalyzed
intermolecular hydroamination of allenes with sulfonamides in
high regio- and stereoselectivity.13 Additionally, a gold- or
palladium-catalyzed intramolecular decarboxylative amination
Received: May 6, 2021
Published: June 11, 2021
https://doi.org/10.1021/acs.joc.1c01065
© 2021 American Chemical Society
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Scheme 1. Selected Examples of Biologically Active Sulfonamides
Scheme 2. Synthetic Methods for N-Functionalized Sulfonamides
we reported an intramolecular allylic amidation of cross-
conjugated sulfonyl iminoesters in preparation of function-
alized N-allyl-N-aryl sulfonamides via decarboxylative aroma-
tization and its potential synthetic application.
successful, it yielded only 22% product (entry 1). Next, yield
was increased to 62% on elevating temperature to 80 °C (entry
2). We sought to evaluate the solvent effect. While replacing
with dichloromethane yielded lower yield (52%, entry 3), the
use of toluene had a detrimental effect on the reaction (entry
4). To our delight, the reaction yield was improved
significantly in dioxane (92%, entry 5). Reducing the quantity
of titanium tetrachloride on a 0.5 decremental basis marginally
reduced the yield (entries 6−8). Control experiments
indicated that titanium tetrachloride and pyridine were
necessary ingredients (entries 9 and 10). Therefore, we used
3 equiv of titanium tetrachloride in dioxane at 80 °C as the
RESULTS AND DISCUSSION
■
At the outset of our studies, we examined conditions for cross-
conjugated sulfonyl iminoester formation (Table 1). The
starting material cross-conjugated ketonester 1a can be
prepared according to our previous report.20 Although the
reaction conducted with 1a and benzenesulfonamide 2a in the
presence of 3 equiv of titanium tetrachloride and 8 equiv of
pyridine using tetrahydrofuran (THF) as a solvent at 0 °C was
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a
Table 1. Optimization of the Cross-Conjugated Sulfonyl Iminoester Formation
b
entry
TiCl4 (equiv)
solvent
T (°C)
yield (%)
1
2
3
4
5
6
7
8
9
3
3
3
3
3
2.5
2
THF
THF
0
22
62
51
0
95
85
80
76
0
80
reflux
80
80
80
80
80
80
80
CH2Cl2
toluene
dioxane
dioxane
dioxane
dioxane
dioxane
dioxane
1.5
c
10
3
0
a
b
Reaction conditions: 1a (0.1 mmol), 2a (0.1 mmol), and pyridine (0.8 mmol) in a 1.0 mL solvent under an argon atmosphere for 24 h. Yield.
c
Without pyridine.
a
Scheme 3. Substrate Scope for N-Sulfonyl Imines
a
Reaction was performed with 1 (0.2−0.5 mmol) and 5 mol % of Pd(PPh3)4 in 1 mL of acetonitrile.
standard conditions in the following experiments for cross-
conjugated sulfonyl iminoesters formation.
(3b) and methylene methyl ester (3d) gave satisfactory yield.
However, C-1 isopropyl-substituted derivatives gave no desired
product, and the starting material was decomposed under these
conditions. To document the scope and versatility with respect
to the sulfonamide substituent, we used a variety of substrates
by keeping n-hexyl as the cross-conjugated ketoester’s
substituent. Sulfonamides with electron-donating substituents
Having optimized the conditions for cross-conjugated
sulfonyl iminoester formation, we looked to study the substrate
scope by varying cross-conjugated ketoester’s substituents
(Scheme 3). Replacing the n-hexyl substituent with methyl
(3c)- or C-2 methyl-substituted derivatives with C-1 n-hexyl
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a
Scheme 4. Substrate Scope of Allylic Amidation
a
Reaction was performed with 3 (0.09−0.2 mmol) and 5 mol % Pd(PPh3)4 in CH2Cl2.
in ortho and para positions gave 3e, 3f, and 3i in 85−90%
yields. The presence of the electron-withdrawing group
provided varying results, while 3h with nitro at the para
position was obtained in 82% yield. Halogenated sulfonamides
produced varying results; their yield reduced with decreased
electronegativity. Compound 3g, with high electronegativity of
the fluorine atom, was obtained in 85%, and those of meta- and
para-chloroulfonamides were 75% (3j) and 78% (3k),
respectively. The presence of ortho-ester and bromo-
substituted sulfonamide was futile (3m and 3l, 0%).
With the cross-conjugated sulfonyl iminoesters in hand, we
next investigated feasibility of performing intramolecular
decarboxylative N-allylation under Pd(PPh3)4 using dichloro-
methane as a solvent at room temperature and the resulting
decarboxylative N-allylation products of 4 are shown in
Scheme 4. Both electron-donating and -withdrawing sulfona-
mides were tolerated and provided 4a−k in excellent yields
(82−99% yields). Overall, neither cross-conjugated ketoester’s
substituents nor those of sulfonamides have detrimental
ramification on decarboxylative N-allylation. Subsequently,
the scope of allyl substituents and regioselectivity of N-
allylation was also investigated. As shown in Scheme 5, the
product obtained, 6a, using the 1-methylallyl substrate was
compatible with these conditions and resulted in 85% yield
with moderate regioselectivity (linear/branched = 1.95:1, entry
1). Exclusively linear products (6b−6d) with excellent yields
were obtained on employing prenyl, 3-alkyl substituted allyl,
cinnamyl, and 1-phenylallyl substrates (entries 2−5). It is
interesting to note that opposite regioselectivity was observed
in the prenyl-substituted substrate of decarboxylative O-
allylation. These results suggest that product formation is
kinetically driven, which is consistent with our previous
report.20
Based on our experiment results, we propose a plausible
mechanism for this intramolecular decarboxylative allylic
amidation reaction (Scheme 6). The substrate 5 is first ionized
by the Pd(0) which leads to the formation of Pd-π-allyl species
and carboxylate ion pair A followed by decarboxylation to give
the sulfonyliminocyclohexadienyl anion and Pd-π-allyl species
ion pair B which then rearomatized to generate a stable N-aryl
sulfonamide anion intermediate C. Finally, the N-allylation of
the N-aryl sulfonamide anion occurred with Pd-π-allyl species
to afford N-allyl-N-aryl sulfonamides 6 as a kinetic product,
and the Pd(0) was regenerated to complete the catalytic cycle.
To further demonstrate the synthetic utility of N-allyl-N-aryl
sulfonamide products, two follow-up transformations were
performed, as shown in Scheme 7. We first submitted N-allyl-
N-aryl sulfonamide 4a under the conditions of PdCl2, Li2CO3,
and CuBr, leading to the formation of 4-aryl-1,2,3,4-
tetrahydroquinoline 7 which can be transformed into
bioactives.21,22 In addition, a bioactive nitrogen-containing β-
hydroxysulfide 8 can also be readily obtained using 4a and
heating it with sulfonyl hydrazides in the presence of FeBr3-bpy
and Na2S2O8.23,24
CONCLUSIONS
■
In summary, we have carried out the cross-conjugated sulfonyl
iminoester formation and their synthesis for N-allyl-N-aryl
sulfonamides through palladium-catalyzed decarboxylative N-
allylation. This reaction proceeds well with good regioselec-
tivity and gives diverse N-allyl-N-aryl sulfonamides, which are
particularly important features of natural products and
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a
,b
Scheme 5. Substrate Scope of Allyl Electrophiles
a
Reaction was performed with 1e−i (1 equiv), sulfonamide (1 equiv), and pyridine (8 equiv) in dioxane. bReaction was performed with 5 (0.1−0.2
c
1
mmol) and 5 mol % Pd(PPh3)4 in CH2Cl2. Ratio was determined by H NMR, l: linear and b: branched.
spectra were recorded on a Varian-Mercury-300 (300 MHz)
pharmaceuticals. Moreover, we have also shown that N-allyl-N-
aryl sulfonamide can be transformed into 4-aryl-1,2,3,4-
tetrahydroquinoline and nitrogen-containing β-hydroxysulfide
bioactive compounds.
spectrometer. Chemical shifts for protons are reported in parts per
million (ppm) downfield from TMS and are referenced to the residual
proton in the NMR solvent (CDCl3 δ = 7.26 ppm and DMSO-d6 δ =
2.49 ppm). 13C{1H} chemical shifts are reported in ppm downfield
from TMS and were referenced to the carbon resonances of the
solvent (CDCl3 δ = 77.0 ppm and DMSO-d6 δ = 39.50 ppm). NMR
data are indicated as follows: chemical shift, multiplicity (br = broad, s
= singlet, d = doublet, t = triplet, q = quartet, and m = multiplet), and
coupling constants in Hertz (Hz). Thin-layer chromatography (TLC)
EXPERIMENTAL SECTION
General Information. All other solvents and reagents were
purified according to standard procedures or were used as received
■
1
from Aldrich, Fluka, Acros, or Lancaster. H, 19F, and 13C{1H} NMR
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Scheme 6. Proposed Mechanism for the Intramolecular Allylic Amidation
Scheme 7. Product Derivatizations to Bioactive Compounds
was performed using Merck silica gel 60 F-254 plates, and detection of
compounds with UV light or dipping into a solution of KMnO4
followed by heating was carried out. Flash column chromatography
was performed using Merck silica gel 60 (40−63 μm) applying a
pressure of about 0.4 bar. The melting point apparatus was obtained
using a Fargo MP-2D. The electron impact (EI) mass spectral data
were obtained using a SHIMADZU QP2020 and JEOL AccuTOF
GCx-plus. Compounds 1a−1d and 1e−1i were prepared according to
the literature procedure.20 Compound 2 was commercially available
(see chemical structures in the Supporting Information).
General Procedure of N-Sulfonyl Imines Synthesis. Com-
pounds 1a−1i (1 equiv) were added into sulfonamide (1 equiv) and
pyridine (8 equiv) in dioxane. Titanium tetrachloride (TiCl4) (3
equiv) was added into the solution under Ar. The reaction mixture
was refluxed for 24 h. The solution was extracted with diethyl ether.
The organic phase was washed with 10% NaHCO3(aq) and saturated
NaCl(aq) and then dried over MgSO4. The solvent was removed using
a rotary evaporator to give the crude mixture. The crude product was
purified by column chromatography to afford the N-sulfonyl imines
3a−3k or 5a−5e.
by column chromatography to afford the N-allyl-N-aryl sulfonamides
4a−4k or 6a−6d.
But-3-en-2-yl 1-Hexyl-4-oxocyclohexa-2,5-diene-1-carboxylate
(1e). According to the general procedure,20 oxalyl chloride (0.6 mL,
7.2 mmol), 1-hexylcyclohexa-2,5-diene-1-carboxylic acid (1.0 g, 4.8
mmol) in dry DCM (20.0 mL), N,N-dimethylformamide (DMF) (0.1
mL), 2-methyl-2-propen-1-ol (0.5 mL, 5.28 mmol), pyridine (0.5 mL,
5.76 mmol), and DMAP (catalytic amount) in DCM (20.0 mL) were
added. The crude product was purified by flash column chromatog-
raphy (EA/hexane) to give but-3-en-2-yl 1-hexylcyclohexa-2,5-diene-
1-carboxylate as a yellow liquid (1.07 g, 85%). Copper iodide (13 mg,
0.69 mmol) and but-3-en-2-yl 1-hexylcyclohexa-2,5-diene-1-carbox-
ylate (600 mg, 2.29 mmol) in acetonitrile (9.5 mL) were added. tert-
Butyl hydroperoxide (TBHP) (70%, 1.5 mL, 16 mmol) was added
into the solution. The crude product was purified by flash column
chromatography (EA/hexane) to give 1e as a yellow liquid (556 mg,
88%). 1H NMR (300 MHz, CDCl3): δ 7.05 (d, J = 12 Hz, 2H), 6.34
(d, J = 9 Hz, 2H), 5.86−5.75 (m, 1H), 5.38−5.34 (m, 1H), 5.26−5.14
(m, 2H), 1.96−1.90 (m, 2H), 1.33−1.23 (m, 11H), 0.84 (t, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 185.3, 169.6, 148.4, 136.7, 123.0,
General Procedure of the Pd-Catalyzed Allylic Amidation
for N-Allyl-N-Aryl Sulfonamide Synthesis. Compounds 3a−3k or
5a−5e and Pd(PPh3)4 (5 mol %) were added into the reaction
container. Dichloromethane (DCM) was added into the container
under Ar gas. The reaction was traced by TLC, and after 1 h at room
temperature, it showed full conversion of the reactant. The mixture
was filtered with Celite, and the solvent was removed using a rotary
evaporator to give the crude mixture. The crude product was purified
116.7, 72.9, 52.6, 38.5, 31.4, 29.2, 24.2, 22.5, 19.8, 14.0. HRMS (EI)
m/z: [M]+ calcd for C17H24O3, 276.1725; found, 276.1718.
3-Methylbut-2-en-1-yl 1-Hexyl-4-oxocyclohexa-2,5-diene-1-car-
boxylate (1f). According to the general procedure,20 oxalyl chloride
(0.6 mL, 7.2 mmol), 1-hexylcyclohexa-2,5-diene-1-carboxylic acid (1
g, 4.8 mmol) in dry DCM (17.8 mL), DMF (0.1 mL), substituted 3-
methyl-2-buten-1-ol (0.5 mL, 5.28 mmol), pyridine (0.5 mL, 5.76
mmol), and DMAP (catalytic amount) in DCM (18.0 mL) were
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added. The crude product was purified by flash column chromatog-
raphy (EA/hexane) to give 3-methylbut-2-en-1-yl 1-hexylcyclohexa-
2,5-diene-1-carboxylate as a yellow liquid (1.034 g, 78%). Copper
iodide (20 mg, 0.11 mmol) and 3-methylbut-2-en-1-yl 1-hexylcyclo-
hexa-2,5-diene-1-carboxylate (970 mg, 3.5 mmol) in acetonitrile (14.6
mL) were added. TBHP (70%, 2.4 mL, 24.5 mmol) was added into
the solution. The crude product was purified by flash column
chromatography (EA/hexane) to give 1f as a yellow liquid (823 mg,
added into the solution. The crude product was purified by flash
column chromatography (EA/hexane) to give 1i as a yellow liquid
(911 mg, 48%). 1H NMR (300 MHz, CDCl3): δ 7.39−7.29 (m, 5H),
7.06 (d, J = 9 Hz, 2H), 6.36 (d, J = 12 Hz, 2H), 6.26 (d, J = 6.0 Hz,
1H), 6.03−5.92 (m, 1H), 5.31−5.24 (m, 2H), 1.95−1.90 (m, 2H),
1.25−1.14 (m, 8H), 0.84 (t, J = 6.8 Hz, 3H). 13C{1H} NMR (75
MHz, CDCl3): δ 185.2, 169.2, 148.0, 148.0, 137.9, 135.34, 130.1,
130.0, 128.6, 128.5, 128.4, 126.9, 77.7, 77.4, 76.9, 76.5, 52.5, 38.5,
31.3, 29.1, 24.1, 22.4, 13.9. HRMS (EI) m/z: [M]+ calcd for
C22H26O3, 338.1882; found, 338.1876.
1
81%). H NMR (300 MHz, CDCl3): δ 7.04 (d, J = 9 Hz, 2H), 6.31
(d, J = 9 Hz, 2H), 5.31−5.28 (m, 1H), 4.60 (d, J = 9 Hz, 2H), 1.93−
1.90 (m, 2H), 1.71 (d, J = 3 Hz, 6H), 1.21−1.20 (m, 8H), 0.83 (t,
3H). 13C{1H} NMR (75 MHz, CDCl3): δ 185.2, 170.3, 148.4, 140.1,
129.8, 117.7, 62.8, 52.5, 38.6, 31.4, 29.1, 25.7, 24.2, 22.4, 18.0, 13.9.
HRMS (EI) m/z: [M]+ calcd for C18H26O3, 290.1882; found,
290.1873.
Allyl-1-hexyl-4-((phenylsulfonyl)imino)cyclohexa-2,5-diene-1-
carboxylate (3a). According to the general procedure, 1a (150 mg,
0.57 mmol), titanium tetrachloride (1 M in toluene, 1.72 mL, 1.72
mmol), benzenesulfonamide (109 mg, 0.57 mmol), and pyridine (0.5
mL, 4.57 mmol) in dioxane (2.4 mL) were added. The crude product
was purified by flash column chromatography (EA/hexane) to give 3a
(E)-Hex-2-en-1-yl 1-Hexyl-4-oxocyclohexa-2,5-diene-1-carboxy-
late (1g). According to the general procedure,20 oxalyl chloride (0.6
mL, 7.2 mmol), 1-hexylcyclohexa-2,5-diene-1-carboxylic acid (1 g, 4.8
mmol), in dry DCM (20.0 mL), DMF (0.1 mL), (E)-hex-2-en-1-ol
(0.5 mL, 5.28 mmol), pyridine (0.5 mL, 5.76 mmol), and DMAP
(catalytic amount) in dry DCM (20.0 mL) were added. The crude
product was purified by flash column chromatography (EA/hexane)
to give (E)-hex-2-en-1-yl 1-hexyl-4-oxocyclohexa-2,5-diene-1-carbox-
ylate as a yellow liquid (1.198 g, 86%). Copper iodide (21 mg, 0.11
mmol) was added into the solution containing (E)-hex-2-en-1-yl 1-
hexyl-4-oxocyclohexa-2,5-diene-1-carboxylate (2 mg, 3.72 mmol) in
acetonitrile (15.5 mL). TBHP (70%, 2.5 mL, 26.0 mmol) was added
into the solution. The crude product was purified by flash column
chromatography (EA/hexane) to give 1g as a yellow liquid (939 mg,
1
as a yellow liquid (211 mg, 92%). H NMR (300 MHz, CDCl3): δ
7.99 (d, J = 6 Hz, 2H), 7.76−7.50 (m, 4H), 7.10−6.97 (m, 2H), 6.44
(d, J = 12 Hz, 1H), 5.95−5.82 (m, 1H), 5.35−5.26 (m, 2H), 4.62 (d,
J = 9 Hz, 2H), 1.98−1.93 (m, 2H), 1.40−1.23 (m, 8H), 0.86 (t, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 169.5, 164.5, 149.2, 147.5, 141.2,
132.7, 131.1, 129.4, 128.8, 127.0, 123.3, 119.3, 66.6, 53.1, 38.9, 31.3,
29.1, 24.3, 22.4, 13.9. HRMS (EI) m/z: [M]+ calcd for C22H27NO4S,
401.1661; found, 401.1653.
Allyl(Z)-1-hexyl-2-methyl-4-((phenylsulfonyl)imino)cyclohexa-
2,5-diene-1-carboxylate (3b). According to the general procedure,
1b (150 mg, 0.54 mmol), titanium tetrachloride (1 M in toluene, 2.2
mL, 2.168 mmol), benzenesulfonamide (85 mg, 0.54 mmol), and
pyridine (0.4 mL, 4.34 mmol) in dioxane (2.2 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
83%). H NMR (300 MHz, CDCl3): δ 7.03 (d, J = 9 Hz, 2H), 6.32
1
(d, J = 12 Hz, 2H), 5.81−5.71 (m, 1H), 5.56−5.46 (m, 1H), 4.55 (d,
J = 6 Hz, 2H), 2.05−2.00 (m, 2H), 1.97−1.89 (m, 2H), 1.42−1.35
(m, 2H), 1.27−1.17 (m, 8H), 0.90−0.81 (m, 6H). 13C{1H} NMR (75
MHz, CDCl3): δ 185.2, 170.1, 148.3, 137.5, 129.9, 123.0, 66.7, 52.5,
38.6, 34.2, 31.4, 29.1, 24.2, 22.4, 21.9, 13.9, 13.5. HRMS (EI) m/z:
[M]+ calcd for C19H28O3, 304.2038; found, 304.2045.
hexane) to give 3b as a yellow liquid (196 mg, 87%). H NMR (300
MHz, CDCl3): δ 7.99 (d, J = 9 Hz, 2H), 7.69−7.47 (m, 4H), 6.79−
6.66 (m, 1H), 6.44−6.26 (m, 1H), 5.86−5.77 (m, 1H), 5.28−5.20
(m, 2H), 4.61−4.48 (m, 2H), 2.16−2.01 (m, 3H), 1.96 (s, 2H),
1.32−1.21 (m, 8H), 0.84 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3):
δ 169.1, 168.9, 165.6, 165.4, 158.6, 156.4, 149.1, 147.3, 141.4, 132.4,
130.8, 129.7, 128.9, 128.6, 126.7, 123.5, 123.2, 119.1, 66.4, 56.4, 35.1,
31.1, 28.9, 23.1, 23.1, 22.3, 21.1, 20.2, 13.7. HRMS (EI) m/z: [M]+
calcd for C23H29NO4S, 415.1817; found, 415.1810.
Cinnamyl 1-Hexyl-4-oxocyclohexa-2,5-dienecarboxylate (1h).
According to the general procedure,20 oxalyl chloride (1.2 mL, 14.4
mmol) was added to a solution of 1-hexylcyclohexa-2,5-diene-1-
carboxylic acid (2 g, 9.6 mmol) in DCM (40.0 mL), DMF (0.2 mL),
(E)-3-phenylprop-2-en-1-ol (1.4 g, 10.56 mmol), pyridine (0.9 mL,
11.52 mmol), and DMAP (catalytic amount) in dry DCM (40.0 mL)
The crude product was purified by flash column chromatography
(EA/hexane) to give cinnamyl 1-hexylcyclohexa-2,5-diene-1-carbox-
ylate as a yellow liquid (2.49 g, 80%). Copper iodide (32 mg, 0.17
mmol) was added into the solution containing cinnamyl 1-
hexylcyclohexa-2,5-diene-1-carboxylate (1.82 g, 5.61 mmol) in
acetonitrile (18.7 mL). TBHP (70%, 5.4 mL, 26.03 mmol) was
added into the solution. The crude product was purified by flash
column chromatography (EA/hexane) to give 1h as a yellow liquid
Allyl-1-methyl-4-((phenylsulfonyl)imino)cyclohexa-2,5-diene-1-
carboxylate (3c). According to the general procedure, 1c (200 mg,
1.04 mmol), titanium tetrachloride (1 M in toluene, 3.1 mL, 3.12
mmol), benzenesulfonamide (163 mg, 1.04 mmol), and pyridine (0.7
mL, 8.32 mmol) in dioxane (4.2 mL) were added. The crude product
was purified by flash column chromatography (EA/hexane) to give 3c
1
as a yellow liquid (276 mg, 80%). H NMR (300 MHz, CDCl3): δ
8.02−7.98 (m, 2H), 7.64−7.50 (m, 4H), 7.09−7.67 (m, 2H), 6.38 (d,
J = 12 Hz, 1H), 5.95−5.82 (m, 1H), 5.34−5.26 (m, 2H), 4.64−4.62
(m, 2H), 1.57 (s, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 169.8,
164.3, 149.6, 148.1, 141.2, 132.8, 131.0, 128.9, 128.5, 127.1, 122.3,
119.3, 66.8, 48.7, 24.7. HRMS (EI) m/z: [M]+ calcd for C17H17NO4S,
331.0878; found, 331.0876.
1
(1.89 g, 85%). H NMR (300 MHz, CDCl3): δ 7.41−7.25 (m, 4H),
7.14−6.99 (m, 3H), 6.78−6.64 (m, 2H), 6.37 (d, J = 12.0 Hz, 1H),
6.32−6.19 (m, 1H), 4.90−4.77 (m, 2H), 2.56 (t, 2H), 199−1.94 (m,
2H), 1.30−1.23 (m, 6H), 0.87 (t, J = 9 Hz, 3H). 13C{1H} NMR (75
MHz, CDCl3): δ 185.3, 170.1, 148.5, 135.8, 135.3, 129.9, 129.2,
128.6, 128.3, 126.6, 121.9, 115.1, 77.6, 77.2, 76.8, 66.6, 52.6, 38.6,
31.4, 29.1, 24.2, 22.4, 14.0. HRMS (EI) m/z: [M]+ calcd for
C22H26O3, 338.1876; found, 338.1878.
Allyl-(Z)-1-(2-methoxy-2-oxoethyl)-2-methyl-4-((phenylsulfonyl)-
imino)cyclohexa-2,5-diene-1-carboxylate (3d). According to the
general procedure, 1d (200 mg, 0.8 mmol), titanium tetrachloride (1
M in toluene, 2.5 mL, 2.5 mmol), benzenesulfonamide (126 mg, 0.8
mmol), and pyridine (0.5 mL, 6.4 mmol) in dioxane (3.2 mL) were
added. The crude product was purified by flash column chromatog-
raphy (EA/hexane) to give 3d as a colorless liquid (265 mg, 82%). 1H
NMR (300 MHz, CDCl3): δ 7.97 (d, J = 9 Hz, 2H), 7.68−7.48 (m,
4H), 7.17−7.07 (m, 1H), 6.44−6.31 (m, 1H), 5.88−5.75 (m, 1H),
5.29−5.21 (m, J = 9 Hz, 2H), 4.59 (d, J = 9 Hz, 2H), 3.63 (s, 3H),
3.27 (d, J = 15 Hz, 1H), 2.66 (d, J = 15 Hz, 1H), 2.05 (d, J = 45 Hz,
3H). 13C{1H} NMR (75 MHz, CDCl3): δ 169.4, 168.1, 164.7, 156.1,
154.1, 147.5, 145.8, 141.3, 132.6, 130.7, 129.3, 129.1, 128.8, 126.9,
123.3, 123.1, 119.4, 67.1, 53.3, 52.1, 39.9, 39.8, 20.9, 20.2. HRMS
(EI) m/z: [M]+ calcd for C20H21NO6S, 403.1090; found, 403.1085.
Allyl-1-hexyl-4-((o-tolylsulfonyl)imino)cyclohexa-2,5-diene-1-
carboxylate (3e). According to the general procedure, 1a (150 mg,
0.57 mmol), 2-methylbenzenesulfonamide (77 mg, 0.57 mmol),
1-Phenylallyl 1-Hexyl-4-oxocyclohexa-2,5-diene-1-carboxylate
(1i). According to the general procedure,20 oxalyl chloride (1.2 mL,
14.4 mmol) was added to a solution of 1-hexylcyclohexa-2,5-diene-1-
carboxylic acid (2 g, 9.6 mmol) in DCM (40.0 mL), DMF (0.2 mL),
1-phenylprop-2-en-1-ol (1.4 g, 10.56 mmol), pyridine (0.9 mL, 11.52
mmol), and DMAP (catalytic amount) in dry DCM (40.0 mL) The
crude product was purified by flash column chromatography (EA/
hexane) to give 1-phenylallyl 1-hexylcyclohexa-2,5-diene-1-carbox-
ylate as a yellow liquid (1.38 g, 34%). Copper iodide (32 mg, 0.17
mmol) was added into the solution containing 1-phenylallyl 1-
hexylcyclohexa-2,5-diene-1-carboxylate (1.82 g, 5.61 mmol) in
acetonitrile (18.7 mL). TBHP (70%, 5.4 mL, 26.03 mmol) was
9090
https://doi.org/10.1021/acs.joc.1c01065
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Article
titanium tetrachloride (1 M in toluene, 1.7 mL, 1.72 mmol), and
pyridine (0.4 mL, 4.57 mmol) in dioxane (2.3 mL) were added. The
crude product was purified by flash column chromatography (EA/
Allyl-4-(((3-chlorophenyl)sulfonyl)imino)-1-hexylcyclohexa-2,5-
diene-1-carboxylate (3j). According to the general procedure,
compound 1a (150 mg, 0.57 mmol), 3-chlorobenzenesulfonamide
(109 mg, 0.57 mmol), titanium tetrachloride (1 M in toluene, 1.7 mL,
1.72 mmol), and pyridine (0.4 mL, 4.57 mmol) in dioxane (2.4 mL)
were added. The crude product was purified by flash column
chromatography (EA/hexane) to give 3j as a yellow liquid (195 mg,
1
hexane) to give 3e as a yellow liquid (202 mg, 85%). H NMR (300
MHz, CDCl3): δ 8.07 (d, J = 9 Hz, 1H), 7.64−7.60 (m, 1H), 7.49−
7.43 (m, 1H), 7.35−7.30 (m, 2H), 7.08−6.96 (m, 2H), 6.43−6.39
(m, 1H), 5.95−5.82 (m, 1H), 5.35−5.25 (m, 2H), 4.63−4.60 (m,
2H), 2.66 (s, 3H).1.98−1.92 (m, 2H), 1.33−1.23 (m, 8H), 0.86 (t,
3H). 13C{1H} NMR (75 MHz, CDCl3): δ 169.5, 164.7, 148.8, 147.4,
139.3, 137.8, 132.8, 132.1, 131.0, 129.4, 127.9, 125.9, 123.5, 119.3,
66.6, 53.1, 38.9, 31.2, 29.1, 24.2, 22.4, 20.5, 13.9. HRMS (EI) m/z:
[M]+ calcd for C23H29NO4S, 415.1817; found, 415.1810.
1
78%). H NMR (300 MHz, CDCl3): δ 7.99−7.98 (m, 1H), 7.90−
7.86 (m, 1H), 7.66−7.44 (m, 3H), 7.12−7.01 (m, 2H), 6.44−6.34
(m, 1H), 5.96−5.83 (m, 1H), 5.36−5.26 (m, 2H), 4.64−4.61 (m,
2H), 2.00−1.94 (m, 2H), 1.33−1.18 (m, 8H), 0.86 (t, 3H). 13C{1H}
NMR (75 MHz, CDCl3): δ 169.4, 165.0, 149.8, 148.1, 143.0, 135.0,
132.8, 131.1, 130.1, 129.3, 127.3, 125.2, 123.4, 119.5, 66.7, 53.3, 39.0,
31.3, 29.2, 24.3, 22.5, 14.0. HRMS (EI) m/z: [M]+ calcd for
C22H26ClNO4S, 435.1271; found, 435.1263.
Allyl-1-hexyl-4-(tosylimino)cyclohexa-2,5-diene-1-carboxylate
(3f). According to the general procedure, 1a (200 mg, 0.76 mmol), 4-
methylbenzenesulfonamide (130 mg, 0.76 mmol), titanium tetra-
chloride (1 M in toluene, 2.3 mL, 2.29 mmol), and pyridine (0.5 mL,
6.1 mmol) in dioxane (3 mL) were added. The crude product was
purified by flash column chromatography (EA/hexane) to give 3f as a
Allyl-4-(((4-chlorophenyl)sulfonyl)imino)-1-hexylcyclohexa-2,5-
diene-1-carboxylate (3k). According to the general procedure, 1a
(200 mg, 0.76 mmol), 4-chlorobenzenesulfonamide (146 mg, 0.76
mmol), titanium tetrachloride (1 M in toluene, 2.3 mL, 2.29 mmol),
and pyridine (0.5 mL, 6.10 mmol) in dioxane (3.0 mL) were added.
The crude product was purified by flash column chromatography
1
yellow liquid (279 mg, 88%). H NMR (300 MHz, CDCl3): δ 7.86
(d, J = 9 Hz, 2H), 7.66−7.62 (m, 1H), 7.30 (d, J = 9 Hz, 2H), 7.07−
6.94 (m, 2H), 6.41−6.37 (m, 1H), 5.94−5.81 (m, 1H), 5.33−5.24
(m, 2H), 4.60 (d, J = 6 Hz, 2H), 2.41 (s, 3H), 1.96−1.91 (m, 2H),
1.24−1.22 (m, 8H), 0.85 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3):
δ 169.5, 164.3, 148.9, 147.3, 143.5, 138.3, 131.0, 129.4, 129.4, 127.0,
123.2, 119.3, 66.6, 53.0, 38.8, 31.3, 29.1, 24.1, 22.4, 21.5, 13.9. HRMS
(EI) m/z: [M]+ calcd for C23H29NO4S, 415.1817; found, 415.1812.
Allyl-4-(((4-fluorophenyl)sulfonyl)imino)-1-hexylcyclohexa-2,5-
diene-1-carboxylate (3g). According to the general procedure, 1a
(150 mg, 0.57 mmol), 4-fluorobenzenesulfonamide (100 mg, 0.57
mmol), titanium tetrachloride (1 M in toluene, 1.7 mL, 1.72 mmol),
and pyridine (0.4 mL, 4.57 mmol) in dioxane (2.28 mL) were added.
The crude product was purified by flash column chromatography
1
(EA/hexane) to give 3k as a yellow liquid (249 mg, 75%). H NMR
(300 MHz, CDCl3): δ 7.91−7.86 (m, 2H), 7.59−7.42 (m, 3H),
7.09−6.96 (m, 2H), 6.38−6.29 (m, 1H), 5.90−5.77 (m, 1H), 5.30−
5.19 (m, 2H), 4.60−4.56 (m, 2H), 1.95−1.90 (m, 2H), 1.23−1.18
(m, 8H), 0.81 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 169.2,
164.6, 149.5, 148.0, 147.9, 130.9, 129.9, 129.1, 128.9, 128.4, 123.1,
119.2, 66.5, 53.1, 38.7, 31.1, 28.9, 24.1, 22.3, 13.8. HRMS (EI) m/z:
[M]+ calcd for C22H26ClNO4S, 435.1271; found, 435.1263.
N-Allyl-N-(4-hexylphenyl)benzenesulfonamide (4a). According
to the general procedure, 3a (40 mg, 0.1 mmol) and Pd(PPh3)4 (6
mg, 0.005 mmol) in DCM (1.0 mL) were added. The crude product
was purified by flash column chromatography (EA/hexane) to give 4a
1
(EA/hexane) to give 3g as a yellow liquid (204 mg, 85%). H NMR
1
as a yellow liquid (35 mg, 99%). H NMR (300 MHz, CDCl3): δ
(300 MHz, CDCl3): δ 8.04−7.98 (m, 2H), 7.63−7.59 (m, 1H),
7.23−7.16 (m, 2H), 7.11−6.88 (m, 2H), 6.42−6.43 (m, 1H), 5.95−
5.82 (m, 1H), 5.35−5.25 (m, 2H), 4.63−4.60 (m, 2H), 1.98−1.93
(m, 2H), 1.33−1.23 (m, 8H), 0.86 (t, 3H). 13C{1H} NMR (75 MHz,
CDCl3): δ 169.4, 166.8, 164.6, 163.4, 149.5, 147.8, 137.4, 131.0,
129.9, 129.3, 123.2, 119.4, 116.2, 115.9, 66.7, 53.2, 38.9, 31.3, 29.1,
24.3, 22.4, 13.9. 19F NMR (282 MHz, CDCl3): δ −105.3. HRMS (EI)
m/z: [M]+ calcd for C22H26FNO4S, 419.1567; found, 419.1558.
Allyl-1-hexyl-4-(((4-nitrophenyl)sulfonyl)imino)cyclohexa-2,5-
diene-1-carboxylate (3h). According to the general procedure, 1a
(100 mg, 0.38 mmol), 4-nitrobenzenesulfonamide (77 mg, 0.38
mmol), titanium tetrachloride (1 M in toluene, 1.0 mL, 0.95 mmol),
and pyridine (0.2 mL, 3.05 mmol) in dioxane (1.5 mL) were added.
The crude product was purified by flash column chromatography
7.63−7.43 (m, 5H), 7.08 (d, J = 6 Hz, 2H), 6.92 (d, J = 9 Hz, 2H),
5.12−5.68 (m, 1H), 5.15−5.05 (m, 2H), 4.18−4.15 (m, 2H), 2.60−
2.54 (m, 2H), 1.61−1.59 (m, 2H), 1.34−1.26 (m, 6H), 0.88 (t, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 142.8, 138.5, 136.4, 132.8, 132.5,
128.8, 128.7, 128.6, 127.6, 118.3, 53.7, 35.5, 31.6, 31.1, 28.9, 22.3,
14.0. HRMS (EI) m/z: [M]+ calcd for C21H27NO2S, 357.1762; found,
357.1757.
N-Allyl-N-(4-hexyl-3-methylphenyl)benzenesulfonamide (4b).
According to the general procedure, 3b (60 mg, 0.14 mmol) and
Pd(PPh3)4 (8 mg, 0.007 mmol) in DCM (1.5 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
hexane) to give 4b as a yellow liquid (52 mg, 97%). H NMR (300
MHz, CDCl3): δ 7.65−7.54 (m, 3H), 7.48−7.42 (m, 2H), 7.01 (d, J =
9 Hz, 1H), 6.83 (s, 1H), 6.70 (d, J = 6 Hz, 1H), 5.81−5.67 (m, 1H),
5.12−5.02 (m, 2H), 4.16−4.13 (m, 2H), 2.56−2.51 (m, 2H), 1.56−
1.51 (s, 3H), 1.37−1.26 (m, 2H), 1.38−1.23 (m, 6H), 0.91−0.87 (m,
3H). 13C{1H} NMR (75 MHz, CDCl3): δ 140.9, 138.6, 136.6, 136.3,
132.9, 132.4, 130.5, 128.9, 128.6, 127.6, 125.6, 118.4, 53.7, 32.8, 31.6,
29.8, 29.2, 22.2, 19.2, 14.0. HRMS (EI) m/z: [M]+ calcd for
C22H29NO2S, 371.1919; found, 371.1910.
1
(EA/hexane) to give 3h as a yellow liquid (140 mg, 82%). H NMR
(300 MHz, CDCl3): δ 8.34 (d, J = 9 Hz, 2H), 8.15 (d, J = 9 Hz, 2H),
7.54 (d, J = 9 Hz, 1H), 7.16−7.05 (m, 2H), 6.39 (d, J = 12 Hz, 1H),
5.93−5.80 (m, 1H), 5.32−5.23 (m, 2H), 4.61 (d, J = 6 Hz, 2H),
1.99−1.94 (m, 2H), 1.28−1.21 (m, 8H), 0.82 (t, 3H). 13C{1H} NMR
(75 MHz, CDCl3): δ 169.0, 165.3, 150.5, 149.9, 148.9, 148.1, 146.7,
130.9, 129.9, 128.9, 128.3, 124.0, 123.2, 119.3, 66.7, 53.4, 38.8, 31.2,
29.0, 24.2, 22.3, 13.8. HRMS (EI) m/z: [M]+ calcd for C22H26N2O6S,
446.1512; found, 446.1505.
N-Allyl-N-(p-tolyl)benzenesulfonamide (4c). According to the
general procedure, 3c (40 mg, 0.12 mmol) and Pd(PPh3)4 (7 mg,
0.006 mmol) in DCM (1.2 mL) were added. The crude product was
purified by column chromatography (EA/hexane) to give 4c as a
Allyl-1-hexyl-4-(((4-methoxyphenyl)sulfonyl)imino)cyclohexa-
2,5-diene-1-carboxylate (3i). According to the general procedure, 1a
(200 mg, 0.76 mmol), 4-methoxybenzenesulfonamide (143 mg, 0.76
mmol), titanium tetrachloride (1 M in toluene, 2.3 mL, 2.29 mmol),
and pyridine (0.5 mL, 6.1 mmol) in dioxane (3 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
yellow liquid (32 mg, 92%). H NMR (300 MHz, CDCl3): δ 7.64−
7.43 (m, 5H), 7.10−7.07 (m, 2H), 6.93−6.88 (m, 2H), 5.80−5.67
(m, 1H), 5.11−5.02 (m, 2H), 4.18−4.15 (m, 2H), 2.32 (s, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 138.4, 137.8, 136.2, 132.8, 132.5,
129.5, 128.7, 128.6, 127.6, 118.7, 53.6, 21.0. HRMS (EI) m/z: [M]+
calcd for C16H17NO2S, 287.0980; found, 287.0972.
1
hexane) to give 3i as a yellow liquid (296 mg, 90%). H NMR (300
MHz, CDCl3): δ 7.91 (d, J = 6 Hz, 2H), 7.66−7.62 (m, 1H), 7.06−
6.93 (m, 4H), 6.41−6.37 (m, 1H), 5.94−5.81 (m, 1H), 5.33−5.24
(m, 2H), 4.60 (d, J = 6 Hz, 2H), 3.85 (s, 3H), 1.96−1.91 (m, 2H),
1.27−1.21 (m, 8H), 0.85 (m, 3H). 13C{1H} NMR (75 MHz, CDCl3):
δ 169.5, 164.0, 162.9, 148.8, 147.2, 133.0, 131.0, 129.5, 129.2, 123.1,
119.3, 114.0, 66.6, 55.5, 53.0, 39.0, 31.3, 29.1, 24.2, 22.4, 13.9. HRMS
(EI) m/z: [M]+ calcd for C23H29NO5S, 431.1766; found, 431.1758.
Methyl-2-(4-(N-allylphenylsulfonamido)phenyl)acetate (4d). Ac-
cording to the general procedure, 3d (60 mg, 0.15 mmol) and
Pd(PPh3)4 (7 mg, 0.007 mmol) in DCM (1.5 mL) were added. The
crude product was purified by flash column chromatography (EA/
hexane) to give 4d as a colorless liquid (44 mg, 82%). 1H NMR (300
MHz, CDCl3): δ 7.64−7.55 (m, 3H), 7.49−7.44 (m, 2H), 7.09 (d, J =
9091
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9 Hz, 1H), 6.91 (s, 1H), 6.75 (d, J = 6 Hz, 1H), 5.80−5.66 (m, 1H),
5.12−5.03 (m, 2H), 4.16−4.13 (m, 2H), 3.69 (s, 3H), 3.60 (s, 2H),
2.24 (s, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 171.6, 138.5,
138.0, 137.8, 132.8, 132.6, 132.5, 131.0, 130.5, 128.8, 127.7, 125.9,
118.8, 53.7, 52.1, 38.6, 19.7. HRMS (EI) m/z: [M]+ calcd for
C19H21NO4S, 359.1191; found, 359.1184.
HRMS (EI) m/z: [M]+ calcd for C22H29NO3S, 387.1868; found,
387.1861.
N-Allyl-3-chloro-N-(4-hexylphenyl)benzenesulfonamide (4j). Ac-
cording to the general procedure, 3j (40 mg, 0.09 mmol) and
Pd(PPh3)4 (5 mg, 0.005 mmol) in DCM (0.9 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
N-Allyl-N-(4-hexylphenyl)-2-methylbenzenesulfonamide (4e).
According to the general procedure, 3e (85 mg, 0.2 mmol) and
Pd(PPh3)4 (12 mg, 0.01 mmol) in DCM (2 mL) were added. The
crude product was purified by flash column chromatography (EA/
hexane) to give 4j as a yellow liquid (30 mg, 85%). H NMR (300
MHz, CDCl3): δ 7.61−7.36 (m, 4H), 7.10 (d, J = 12 Hz, 2H), 6.92
(d, J = 12 Hz, 2H), 5.81−5.68 (m, 1H), 5.13−5.05 (m, 2H), 4.16 (d,
J = 6 Hz, 2H), 2.61−2.55 (m, 2H), 1.59−1.54 (m, 2H), 1.33−1.26
(m, 6H), 0.88 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 143.1,
140.3, 136.0, 135.0, 132.6, 132.5, 130.0, 129.0, 128.6, 127.7, 125.7,
119.0, 53.9, 35.5, 31.6, 31.1, 28.9, 22.6, 14.1. HRMS (EI) m/z: [M]+
calcd for C21H26ClNO2S, 391.1373; found, 391.1364.
1
hexane) to give 4e as a yellow liquid (71 mg, 95%). H NMR (300
MHz, CDCl3): δ 7.82−7.79 (m, 1H), 7.44−7.39 (m, 1H), 7.27−7.23
(m, 2H), 7.0.8−6.98 (m, 4H), 5.82−5.73 (m, 1H), 5.10−5.04 (m,
2H), 4.24−4.21 (m, 2H), 2.58−2.53 (m, 2H), 2.35 (s, 3H), 1.63−
1.54 (m, 2H), 1.28 (m, 6H), 0.87 (t, 3H). 13C{1H} NMR (75 MHz,
CDCl3): δ 142.7, 138.1, 136.9, 136.2, 133.0, 132.6, 132.5, 130.2,
128.9, 128.7, 126.0, 118.7, 53.8, 35.4, 31.6, 31.1, 28.8, 22.6, 20.7, 14.0.
HRMS (EI) m/z: [M]+ calcd for C22H29NO2S, 371.1919; found,
371.1916.
N-Allyl-4-chloro-N-(4-hexylphenyl)benzenesulfonamide (4k). Ac-
cording to the general procedure, 3k (60 mg, 0.14 mmol) and
Pd(PPh3)4 (8 mg, 0.007 mmol) in DCM (1.4 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
hexane) to give 4k as a yellow liquid (49 mg, 91%). H NMR (300
N-Allyl-N-(4-hexylphenyl)-4-methylbenzenesulfonamide (4f).
According to the general procedure, 3f (140 mg, 0.34 mmol) and
Pd(PPh3)4 (19 mg, 0.02 mmol) in DCM (3.3 mL) were added. The
crude product was purified by flash column chromatography (EA/
MHz, CDCl3): δ 7.56−7.52 (m, 2H), 7.44−7.41 (m, 2H), 7.10 (d, J =
9 Hz, 2H), 6.93−6.91 (m, 2H), 5.78−5.67 (m, 1H), 5.13−5.04 (m,
2H), 4.17−4.14 (m, 2H), 2.60−2.55 (m, 2H), 1.62−1.54 (m, 2H),
1.34−1.26 (m, 6H), 0.88 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3):
δ 169.2, 164.6, 149.5, 148.0, 147.9, 130.9, 129.9, 129.1, 128.9, 128.4,
123.7, 119.2, 66.5, 53.1, 38.7, 31.1, 28.9, 24.1, 22.3, 13.8. HRMS (EI)
m/z: [M]+ calcd for C21H26ClNO2S, 391.1373; found, 391.1367.
But-3-en-2-yl-1-hexyl-4-((phenylsulfonyl)imino)cyclohexa-2,5-
diene-1-carboxylate (5a). According to the general procedure, 1e
(100 mg, 0.36 mmol) was added into 2a (57 mg, 0.36 mmol) and
pyridine (0.3 mL, 2.88 mmol) in dioxane (1.4 mL). Titanium
tetrachloride (1 M in toluene, 0.9 mL, 0.9 mmol) was added into the
solution under Ar. The crude product was purified by flash column
chromatography (EA/hexane) to give 5a as a yellow liquid (104 mg,
1
hexane) to give 4f as a yellow liquid (119 mg, 95%). H NMR (300
MHz, CDCl3): δ 7.52 (d, J = 9 Hz, 2H), 7.29−7.26 (m, 2H), 7.11 (d,
J = 6 Hz, 2H), 6.95 (d, J = 12 Hz, 2H), 5.83−5.70 (m, 1H), 5.14−
5.04 (m, 2H), 4.19−4.16 (m, 2H), 2.62−2.57 (m, 2H), 2.45 (s, 3H),
1.67−1.59 (m, 2H), 1.37−1.29 (m, 6H), 0.91 (t, 3H). 13C{1H} NMR
(75 MHz, CDCl3): δ 143.2, 142.6, 136.4, 135.4, 132.8, 129.3, 128.7,
128.5, 127.6, 118.5, 53.5, 35.4, 31.6, 31.0, 28.9, 22.5, 21.5, 14.0
HRMS (EI) m/z: [M]+ calcd for C22H29NO2S, 371.1919; found,
371.1914.
N-Allyl-4-fluoro-N-(4-hexylphenyl)benzenesulfonamide (4g). Ac-
cording to the general procedure, 3g (55 mg, 0.13 mmol) and
Pd(PPh3)4 (7.6 mg, 0.007 mmol) in DCM (1.3 mL) were added. The
crude product was purified by flash column chromatography (EA/
1
70%). H NMR (300 MHz, CDCl3): δ 8.02−7.98 (m, 2H), 7.58−
7.51 (m, 4H), 7.10−6.97 (m, 2H), 6.40 (d, 1H) 5.85−5.74 (m, 1H),
5.38−5.33 (m, 1H), 5.26−5.15 (m, 2H), 1.95−1.90 (m, 2H), 1.33−
1.22 (m, 11H), 0.85 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ
169.0, 164.6, 149.5, 147.8, 141.2, 136.5, 132.7, 129.3, 128.8, 127.0,
123.2, 116.9, 73.2, 53.2, 39.0, 31.3, 29.1, 24.3, 22.4, 19.7, 13.9. HRMS
(EI) m/z: [M]+ calcd for C23H29NO4S, 415.1817; found, 415.1814.
3-Methylbut-2-en-1-yl-1-hexyl-4-((phenylsulfonyl)imino)-
cyclohexa-2,5-diene-1-carboxylate (5b). According to the general
procedure, 1f (200 mg, 0.69 mmol) was added into 2a (108 mg, 0.69
mmol) and pyridine (0.5 mL, 5.51 mmol) in dioxane (2.8 mL).
Titanium tetrachloride (1 M in toluene, 2.1 mL, 2.07 mmol) was
added into the solution under Ar. The crude product was purified by
flash column chromatography (EA/hexane) to give 5b as a yellow
liquid (213 mg, 72%). 1H NMR (300 MHz, DMSO-d6): δ 7.93−7.89
(m, 2H), 7.71−7.60 (m, 3H), 7.45 (d, J = 9 Hz, 1H), 7.28 (d, J = 9
Hz, 1H), 7.13 (d, J = 9 Hz, 1H), 6.45 (d, J = 9 Hz, 1H), 5.31−5.25
(m, 1H), 4.61 (d, J = 6 Hz, 2H), 1.99−1.91 (m, 2H), 1.69 (d, J = 15
Hz, 6H), 1.23−1.17 (m, 8H), 0.83 (t, 3H). 13C{1H} NMR (75 MHz,
DMSO-d6): δ 169.5, 165.2, 151.8, 149.9, 141.4, 134.0, 133.6, 129.8,
129.1, 127.0, 122.8, 118.4, 63.1, 53.7, 37.9, 31.3, 29.0, 25.9, 24.2, 22.4,
18.3, 14.3. HRMS (EI) m/z: [M]+ calcd for C24H31NO4S, 429.1974;
found, 429.1967.
1
hexane) to give 4g as a yellow liquid (40 mg, 82%). H NMR (300
MHz, CDCl3): δ 7.64−7.58 (m, 2H), 7.15−7.07 (m, 4H), 6.93−6.90
(m, 2H), 5.78−5.37 (m, 1H), 5.12−5.04 (m, 2H), 4.16−4.14 (m,
2H), 2.60−2.54 (m, 2H), 1.61−1.56 (m, 2H), 1.30−1.29 (m, 6H),
0.88 (t, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 166.7, 163.3, 143.0,
136.2, 134.7, 132.7, 130.4, 130.3, 128.9, 128.6, 118.8, 116.1, 115.8,
53.7, 35.5, 31.6, 31.1, 28.9, 22.6, 14.0. 19F NMR (282 MHz, CDCl3):
δ −105.4. HRMS (EI) m/z: [M]+ calcd for C21H26FNO2S, 375.1668;
found, 375.1666.
N-Allyl-N-(4-hexylphenyl)-4-nitrobenzenesulfonamide (4h). Ac-
cording to the general procedure, 3h (75 mg, 0.17 mmol) and
Pd(PPh3)4 (10 mg, 0.008 mmol) in DCM (1.7 mL) were added. The
crude product was purified by flash column chromatography (EA/
hexane) to give 4h as a white solid (57 mg, 85%). Melting point: 83−
1
84 °C. H NMR (300 MHz, CDCl3): δ 8.30 (d, J = 9 Hz, 2H), 7.78
(d, J = 9 Hz, 2H), 7.11 (d, J = 9.0 Hz, 2H), 6.91 (d, J = 6 Hz, 2H),
5.81−5.68 (m, 1H), 5.15−5.08 (m, 2H), 4.20 (d, J = 6 Hz, 2H), 2.58
(t, 2H), 1.61−1.59 (m, 2H), 1.30−1.25 (m, 6H), 0.87 (t, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 149.9, 144.4, 143.5, 135.6, 132.2,
129.2, 128.8, 128.5, 124.0, 119.4, 54.1, 35.5, 31.6, 31.1, 28.9, 22.6,
14.1. HRMS (EI) m/z: [M]+ calcd for C21H26N2O4S, 402.1613;
found, 402.1606.
(E)-Hex-2-en-1-yl-1-hexyl-4-((phenylsulfonyl)imino)cyclohexa-
2,5-diene-1-carboxylate (5c). According to the general procedure, 1g
(100 mg, 0.33 mmol) was added into 2a (52 mg, 0.33 mmol) and
pyridine (0.2 mL, 2.63 mmol) in dioxane (1.3 mL). Titanium
tetrachloride (1 M in toluene, 1.0 mL, 0.99 mmol) was added into the
solution under Ar. The crude product was purified by flash column
chromatography (EA/hexane) to give 5c as a yellow liquid (110 mg,
N-Allyl-N-(4-hexylphenyl)-4-methoxybenzenesulfonamide (4i).
According to the general procedure, 3i (90 mg, 0.2 mmol) and
Pd(PPh3)4 (12 mg, 0.01 mmol) in DCM (2.0 mL) were added. The
crude product was purified by flash column chromatography (EA/
hexane) to give 4i as a white solid (74 mg, 95%). Melting point: 48−
1
1
76%). H NMR (300 MHz, CDCl3): δ 8.02−7.98 (m, 2H), 7.65−
49 °C. H NMR (300 MHz, CDCl3): δ 7.56−7.51 (m, 2H), 7.09−
7.49 (m, 4H), 7.10−6.98 (m, 2H), 6.41 (d, J = 6 Hz, 1H), 5.83−5.74
(m, 1H), 5.57−5.48 (m, 1H), 4.57 (d, J = 6 Hz, 2H), 2.08−2.00 (m,
2H), 1.95 (d, J = 9 Hz, 2H), 1.45−1.35 (m, 2H), 1.23 (s, 8H), 0.93−
0.84 (m, 6H). 13C{1H} NMR (75 MHz, CDCl3): δ 169.7, 164.7,
149.5, 147.9, 141.4, 137.8, 132.7, 129.4, 128.8, 127.1, 123.2, 122.9,
7.07 (m, 2H), 6.95−6.89 (m, 4H) 5.80−5.67 (m, 1H), 5.10−5.02 (m,
2H), 4.15−4.12 (m, 2H), 3.86 (s, 3H), 2.59−2.54 (m, 2H), 1.62−
1.56 (m, 2H), 1.33−1.25 (m, 6H), 0.88 (t, 3H). 13C{1H} NMR (75
MHz, CDCl3): δ 162.7, 142.5, 136.5, 132.8, 129.9, 129.6, 128.6,
128.5, 118.4, 113.7, 55.4, 53.4, 35.4, 31.6, 30.9, 28.8, 22.5, 14.0.
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67.0, 53.2, 39.0, 34.2, 31.4, 29.2, 24.4, 22.5, 21.9, 14.0, 13.6. HRMS
(EI) m/z: [M]+ calcd for C25H33NO4S, 443.2130; found, 443.2123.
Cinnamyl-1-hexyl-4-((phenylsulfonyl)imino)cyclohexa-2,5-
diene-1-carboxylate (5d). According to the general procedure, 1h
(400 mg, 1.18 mmol) was added into 2a (183 mg, 1.18 mmol) and
pyridine (0.8 mL, 9.45 mmol) in dioxane (4.7 mL). Titanium
tetrachloride (1 M in toluene, 3.5 mL, 3.55 mmol) was added into the
solution under Ar. The crude product was purified by flash column
chromatography (EA/hexane) to give 5d as a yellow liquid (423 mg,
(m, 2H), 1.29−1.26 (m, 6H), 1.24−1.16 (m, 2H), 0.9−0.86 (m, 3H),
0.75−0.67 (m, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 142.5,
138.7, 136.3, 135.6, 132.3, 128.7, 128.6, 128.6, 127.6, 124.2, 53.1,
35.4, 34.0, 31.6, 31.1, 28.8, 22.5, 21.9, 14.0, 13.2. HRMS (EI) m/z:
[M]+ calcd for C24H33NO2S, 399.2232; found, 399.2223.
N-Cinnamyl-N-(4-hexylphenyl)benzenesulfonamide (6d). Ac-
cording to the general procedure, 5d or 5e (35 mg, 0.07 mmol)
and Pd(PPh3)4 (4 mg, 0.004 mmol) were added into the reaction
container. DCM (0.7 mL) was added into the container under Ar gas.
The crude product was purified by flash column chromatography
(EA/hexane) to give 6d as a yellow liquid (26 mg, 83% from 5d; 27
1
75%). H NMR (300 MHz, CDCl3): δ 8.02−7.99 (m, 2H), 7.68−
7.49 (m, 5H), 7.42−7.28 (m, 6H), 7.11−6.99 (m, 3H), 6.66 (d, J =
15 Hz, 1H), 6.43 (d, J = 9 Hz, 1H), 6.30−6.20 (m, 1H), 4.78 (d, J = 6
Hz, 2H), 1.98 (d, J = 9 Hz, 2H), 1.23 (s, 8H), 0.85 (t, J = 12 Hz, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 169.7, 164.6, 149.3, 147.7, 141.3,
1
mg, 85% from 5e). H NMR (300 MHz, CDCl3): δ 7.66−7.64 (m,
2H), 7.61−7.55 (m, 1H), 7.49−7.44 (m, 2H), 7.29−7.18 (m, 5H),
7.08 (d, J = 9 Hz, 2H), 6.96 (d, J = 9 Hz, 2H), 6.39 (d, J = 15 Hz,
1H), 6.16−6.06 (m, 1H), 4.33 (d, J = 3 Hz, 2H), 2.59−2.54 (m, 2H),
1.60−1.55 (m, 2H), 1.29 (s, 6H), 0.9−0.85 (m, 3H). 13C{1H} NMR
(75 MHz, CDCl3): δ 142.7, 138.6, 136.4, 136.2, 133.5, 132.5, 132.4,
128.8, 128.7, 128.5, 128.4, 127.6, 127.5, 126.3, 124.1, 124.0, 53.4,
35.4, 31.5, 31.0, 28.8, 22.4, 13.9. HRMS (EI) m/z: [M]+ calcd for
C27H31NO2S, 433.2075; found, 433.2069.
135.8, 135.6, 132.7, 129.4, 128.8, 127.0, 126.6, 123.4, 123.3, 121.9,
121.8, 66.8, 53.2, 39.0, 31.4, 29.2, 24.4, 22.5, 14.0. HRMS (EI) m/z:
[M]+ calcd for C28H31NO4S, 477.1974; found, 477.1966.
1-Phenylallyl 1-Hexyl-4-((phenylsulfonyl)imino)cyclohexa-2,5-
diene-1-carboxylate (5e). According to the general procedure, 1i
(230 mg, 0.68 mmol) was added into 2a (160 mg, 1.02 mmol) and
pyridine (0.5 mL, 9.45 mmol) in dioxane (2.04 mL). Titanium
tetrachloride (1 M in toluene, 2.0 mL, 2.04 mmol) was added into the
solution under Ar. The crude product was purified by flash column
chromatography (EA/hexane) to give 5e as a yellow liquid (181 mg,
56%). 1H NMR (300 MHz, CDCl3): δ 8.01 (d, J = 9.0 Hz, 2H), 7.65
(d, J = 11.8 Hz, 1H), 7.58−7.51 (m, 2H), 7.33−7.26 (m, 5H), 7.12−
7.0 (m, 2H), 6.34 (dd, J = 6, 9 Hz, 2H), 6.04−5.93 (m, 1H), 5.40−
5.25 (m, 2H), 1.90−1.94 (m, 2H), 1.25−1.18 (m, 8H), 0.85 (t, J =
7.5 Hz, 3H). 13C{1H} NMR (75 MHz, CDCl3): δ 168.6, 164.5, 149.1,
147.5, 141.2, 137.8, 135.2, 132.7, 129.4, 128.8, 127.0 126.9, 123.3,
117.9, 78.0, 77.4, 76.9, 76.5, 53.2, 39.0, 31.3, 29.1, 24.3, 22.4, 13.9.
HRMS (EI) m/z: [M]+ calcd for C28H31NO4S, 477.1974; found,
477.1968.
6-Hexyl-1-(phenylsulfonyl)-4-(p-tolyl)-1,2,3,4-tetrahydroquino-
line (7). In an oven-dried 25 mL Schlenk tube under argon were
successively placed 4a (102 mg, 0.29 mmol), 4-methylbenzenesul-
fonyl chloride (109 mg, 0.59 mmol), PdCl2 (3 mg, 0.01 mmol), CuBr
(20 mg, 0.14 mmol), Li2CO3 (63 mg, 0.86 mmol), and 1,4-dioxane
(0.9 mL). Then, the reaction mixture was settled in a preheated (140
°C) oil bath for 20 h with stirring. The crude product was purified by
flash column chromatography (EA/hexane) to give 7 as a yellow
liquid (114 mg, 90%). 1H NMR (300 MHz, CDCl3): δ 7.84 (d, J = 9
Hz, 1H), 7.65 (d, J = 9 Hz, 2H), 7.60−7.55 (m, 1H), 7.42 (t, 2H),
7.06−7.03 (m, 1H), 6.96 (d, J = 6 Hz, 2H), 6.55−6.49 (m, 3H),
4.12−4.03 (m, 1H), 3.80−3.68 (m, 2H), 2.45−2.39 (m, 2H), 2.29 (s,
3H), 1.91−1.85 (m, 1H), 1.65−1.58 (m, 1H), 1.48 (d, J = 6 Hz, 2H),
1.25 (d, J = 12 Hz, 6H), 0.89−0.83 (m, 3H). 13C{1H} NMR (75
MHz, CDCl3): δ 142.1, 139.8, 139.7, 135.9, 134.5, 132.5, 130.0,
130.1, 129.0, 128.0, 127.3, 127.0, 124.6, 124.5, 45.4, 42.8, 35.1, 31.6,
31.2, 30.5, 28.7, 22.9, 21.0, 14.1. HRMS (EI) m/z: [M]+ calcd for
C28H33NO2S, 447.2232; found, 447.2224.
N-(4-Hexylphenyl)-N-(2-hydroxy-3-(phenylthio)propyl)-
benzenesulfonamide (8). A 35 mL Schlenk-type tube equipped with
a magnetic stir bar was charged with 4a (200 mg, 0.56 mmol) and
benzenesulfonyl hydrazide (191 mg, 1.12 mmol). Then, FeBr3(33 mg,
0.11 mmol), 2,2′-dipyridyl (18 mg, 0.11 mmol), Na2S2O8 (533 mg,
2.24 mmol), 1,4-dioxane (2.2 mL), and H2O (0.22 mL) were added
to this system. The tube was then sealed and placed in an oil bath at
120 °C. After the reaction mixture was stirred for 24 h, it was allowed
to cool to ambient temperature. The reaction mixture was filtered,
and the solvent was removed to give the crude product. The residue
was purified by column chromatography (EA/hexane) to afford 8 as a
brown liquid (151 mg, 56%). 1H NMR (300 MHz, CDCl3): δ 7.60−
7.56 (m, 3H), 7.45 (t, J = 9 Hz, 2H), 7.27−7.06 (m, 7H), 6.91−6.87
(m, 2H), 3.75−3.64 (m, 3H), 3.21 (dd, J = 14.0, 4.6 Hz, 1H), 2.97
(dd, J = 14.0, 7.0 Hz, 1H), 2.78 (s, 1H), 2.61−2.53 (m, 2H), 1.35−
1.24 (m, 8H), 0.89 (d, J = 6.2 Hz, 3H). 13C{1H} NMR (75 MHz,
CDCl3): δ 143.2, 137.6, 136.8, 134.9, 132.8, 130.0, 129.1, 128.9,
128.8, 128.2, 127.7, 126.6, 77.4, 76.9, 76.5, 67.8, 55.5, 38.9, 35.4, 31.6,
31.1, 28.9, 22.5, 14.0. HRMS (EI) m/z: [M]+ calcd for C27H33NO3S2,
483.1902; found, 483.1862.
(E)-N-(But-2-en-1-yl)-N-(4-hexylphenyl)benzenesulfonamide
(6a), N-(But-3-en-2-yl)-N-(4-hexylphenyl)benzenesulfonamide
(6a′) (6a:6a′ = 1.95:1). According to the general procedure, 5a
(100 mg, 0.24 mmol) and Pd(PPh3)4 (14 mg, 0.012 mmol) were
added into the reaction container. DCM (2.4 mL) was added into the
container under Ar gas. The crude product was purified by flash
column chromatography (EA/hexane) to give 6a and 6a′ (mixture) as
1
a yellow liquid (89 mg, 85%, 6a:6a′ = 1.95:1). H NMR (300 MHz,
CDCl3): δ 7.74−7.71 (m, 1H), 7.66−7.50 (m, 2H), 7.44 (m, 2H),
7.17−7.02 (m, 2H), 6.93−6.89 (m, 2H), 5.77−5.66 (m, 1H), 5.53−
5.33 (m, 1H), 5.08−4.96 (m, 1H), 4.40−4.48 (m, 6a′, 1H), 4.09 (d, J
= 6 Hz, 6a, 1H), 2.61−2.54 (m, 2H), 1.58 (m, 3H), 1.33−1.14 (m,
8H), 0.88 (m, 3H). HRMS (EI) m/z: [M]+ calcd for C22H29NO2S,
371.1913; found, 371.1911.
N - ( 4 - H e x y l p h e n y l ) - N - ( 3 - m e t h y l b u t - 2 - e n - 1 - y l ) -
benzenesulfonamide (6b). According to the general procedure, 5b
(72 mg, 0.18 mmol) and Pd(PPh3)4 (10 mg, 0.009 mmol) were
added into the reaction container. DCM (1.8 mL) was added into the
container under Ar gas. The crude product was purified by flash
column chromatography (EA/hexane) to give 6b as a yellow liquid
1
(55 mg, 80%). H NMR (300 MHz, CDCl3): δ 8.01−7.98 (m, 2H),
7.64−7.49 (m, 4H), 7.09−6.98 (m, 2H), 6.40 (d, J = 9 Hz, 1H),
5.33−5.28 (m, 1H), 4.62 (d, J = 9 Hz, 2H), 1.94 (d, J = 9 Hz, 2H),
1.74 (d, J = 15 Hz, 6H), 1.24 (d, J = 6 Hz, 8H), 0.88−0.84 (m, 3H).
13C{1H} NMR (75 MHz, CDCl3): δ 169.8, 164.8, 149.7, 148.0, 141.3,
140.4, 132.7, 129.3, 128.8, 127.0, 123.2, 117.6, 63.1, 53.2, 39.0, 31.4,
29.2, 25.8, 24.3, 22.5, 18.1, 14.0. HRMS (EI) m/z: [M]+ calcd for
C23H31NO2S, 385.2075; found, 385.2073.
(E)-N-(Hex-2-en-1-yl)-N-(4-hexylphenyl)benzenesulfonamide
(6c). According to the general procedure, 5c (72 mg, 0.16 mmol) and
Pd(PPh3)4 (9 mg, 0.008 mmol) were added into the reaction
container. DCM (1.6 mL) was added into the container under Ar gas.
The crude product was purified by flash column chromatography
ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.1c01065.
1
(EA/hexane) to give 6c as a yellow liquid (55 mg, 86%). H NMR
(300 MHz, CDCl3): δ 7.63−7.53 (m, 3H), 7.47−7.42 (m, 2H), 7.07
(d, J = 9 Hz, 2H), 6.89 (d, J = 6 Hz, 2H), 5.46−5.27 (m, 2H), 4.10
(d, J = 9 Hz, 2H), 2.59−2.54 (m, 2H), 1.89−1.82 (m, 2H), 1.64−1.53
Chemical structures of 1 and 2 and NMR spectra (PDF)
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AUTHOR INFORMATION
Corresponding Author
Chih-Ming Chou − Department of Applied Chemistry,
National University of Kaohsiung, 81148 Kaohsiung,
Taiwan; orcid.org/0000-0002-9894-5365;
Email: cmchou@nuk.edu.tw
■
Authors
Tzu-Lun Liu − Department of Applied Chemistry, National
University of Kaohsiung, 81148 Kaohsiung, Taiwan
Meng-Li Jhou − Department of Applied Chemistry, National
University of Kaohsiung, 81148 Kaohsiung, Taiwan
Cheng-En Hsieh − Department of Applied Chemistry,
National University of Kaohsiung, 81148 Kaohsiung,
Taiwan
Chia-Jung Lin − Department of Applied Chemistry, National
University of Kaohsiung, 81148 Kaohsiung, Taiwan
Hsiu-Hui Su − Department of Applied Chemistry, National
University of Kaohsiung, 81148 Kaohsiung, Taiwan
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.1c01065
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We gratefully thank the National University of Kaohsiung and
the Ministry of Science and Technology of Taiwan (MOST
108-2113-M-390-004-MY2) for their financial support. The
Core Facility Center at National Cheng Kung University
(HRMS) is acknowledged.
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