From Furan-Yne Systems to para -Benzoquinone Derivatives: Gold-Catalyzed Cyclization and Oxidation, and Further Reduction by Sodium Dithionate

Article abstract of DOI:10.1055/s-0040-1707371

A series of furan-yne systems were transformed into the corresponding para -benzoquinone derivatives by gold(ΙΙΙ) catalyst. The two-step procedure consisted of a phenol synthesis and subsequent oxidation with iodobenzene diacetate. The reactions can be carried out in a one-pot procedure with the same precatalyst. The para -benzoquinone could simply be converted into the corresponding hydroquinones by reduction with sodium dithionate. This protocol features high efficiency, mild conditions, and wide substrate scopes.

Full text of DOI:10.1055/s-0040-1707371

SYNTHESIS
0
0
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9
-
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8
1
1
4
3
7
-
2
1
0
X
Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart
2020, 52, A–J
paper
A
en
S. Ahmadi, M. Ghanbari
Paper
Synthesis
From Furan–Yne Systems to para-Benzoquinone Derivatives:
Gold-Catalyzed Cyclization and Oxidation, and Further Reduction
by Sodium Dithionate
Saman Ahmadi
Mohammad Ghanbari*
R2
R2
O
R2
G
O
S
O
S
O
S
R1
G
R1
PhI(OAc)2
AuCl3
G
R1
O
O
O
O
Department of Organic Chemistry, Faculty of Chemistry,
University of Kashan, Kashan, Iran
ghanbari-m@kashanu.ac.ir
OH
10 examples
O
Yield: 62–89%
G = N, O
R1 = Ph, 4-MeC6H4, 4-NO2C6H4, 4-MeOC6H4
R2 = H, Ph, 4-MeC6H4, 4-MeOC6H4, Et
Corresponding Author
MDeMeopahaialrmtgmhmaeandbtaoGrfhi-Oamnrg@baaknraicshCahneum.aics.tiry, Faculty of Chemistry, University of Kashan, Kashan, Iran
Received: 19.01.2020
Accepted after revision: 01.08.2020
Published online: 23.09.2020
Since other known para-benzoquinone derivatives pos-
sess outstanding pharmaceutical applications such as, anti-
biotics,6 anticoagulants,7 antineoplastics,8 synthetic studies
of para-benzoquinones skeleton have been actively carried
out.
DOI: 10.1055/s-0040-1707371; Art ID: ss-2020-n0456-op
Abstract A series of furan–yne systems were transformed into the
corresponding para-benzoquinone derivatives by gold(ΙΙΙ) catalyst. The
two-step procedure consisted of a phenol synthesis and subsequent ox-
idation with iodobenzene diacetate. The reactions can be carried out in
a one-pot procedure with the same precatalyst. The para-benzoqui-
none could simply be converted into the corresponding hydroquinones
by reduction with sodium dithionate. This protocol features high effi-
ciency, mild conditions, and wide substrate scopes.
Gold has emerged in the field of organic chemistry as a
powerful tool and, due to the high selectivity as well as mild
reaction conditions, has become one of the major topics in
catalysis research.9 The extraordinary ability of gold to acti-
vate multiple bonds has led to a large number of new ap-
proaches for the construction of various heterocyclic struc-
tures.10,11 Most of these reactions are atom-economical and
in comparison to classical routes, the reaction conditions
are dramatically mild in most cases.12 In 2000, the Hashmi
group published the gold-catalyzed transformation of alle-
nyl ketones to furans by a 5-endo-trig cyclization.13 Based
on these findings, a large family of gold-catalyzed heterocy-
cle syntheses was developed by different groups. Inspired
by the recent reports on gold-catalyzed cyclization reac-
tions,11,14,15 and as part of our ongoing research program on
the development of efficient methods for the preparation of
heterocyclic compounds,16 herein, we report a one-pot re-
action that includes gold-catalyzed phenol synthesis and
subsequently, gold-assisted oxidation reaction as a promis-
ing strategy for synthesis of novel para-benzoquinone
structures (Scheme 1).
Key words gold catalyst, furfural, alkyne, benzoquinone, one-pot re-
action
para-Benzoquinone is the fundamental structure of qui-
nonoid compounds. They are broadly scattered in the natu-
ral world, being found in plants, bacteria, and arthropods
and, hence, quinones are ubiquitous in living systems.1 Qui-
nones play a vital role in biological functions, including
electron transfer and oxidative phosphorylation.2 Their role
as electron transfer agents in primary metabolic processes
like respiration and photosynthesis is pivotal to human life.
para-Benzoquinone derivatives such as Streptonigrin
(STN),3 Mitomycin C,4 and Xylariaquinone A5 are examples
of the most well-known antitumor, anticancer, and antima-
larial structures, respectively (Figure 1).
G = N,O
O
O
R2
G
R2
G
MeO
H2N
O
NH2
O
S
O
S
sequential reaction
(two-steps, one-pot)
O
O
R1
R1
N
COOH
Me
O
O
O
N
Me
H
O
H
Me
O
O
H2N
O
1
O
R2
O
3
O
H2N
HO
OH
OMe
N
NH
G
S
R1
Aucl3 (5 mol%)
MeCN
PhI(OAc)2
H2O
O
O
MeO
Xylariaquinone
Mitomycin C
STN
OH
OMe
2
Figure 1 Number of well-known para-benzoquinone structures
Scheme 1 Gold-catalyzed synthesis of parabenzoquinones 3
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
S. Ahmadi, M. Ghanbari
Paper
Synthesis
A possible one-pot procedure would be attractive, as
purification of the intermediates could be circumvented,
which saves time and reduces the waste of production. In
2011, Wang and co-workers reported gold-catalyzed direct
acetoxylation of arenes with PhI(OAc)2 (Scheme 2).17
15 mol% aqueous HCl in the absence of gold catalyst was
performed and we observed that no reaction occurred (en-
try 7). The best conditions for the formation of 3a from 2a
involved the use of 5-methyl-2-tosylisoindolin-4-ol (2a; 1.0
equiv), PhI(OAc)2 (2.0 equiv), and AuCl3 (5 mol%) in MeCN
(2 mL) and H2O (1 mL) at room temperature for 1 hour un-
der an air atmosphere (entry 5).
X
X
AuCl3 (2–5 mol%)
OAc
PhI(OAc)2 DCE, 110 °C
Table 1 Optimization of Reaction Conditionsa
Scheme 2 Direct acetoxylation of arenes
Inspired by Wang et al.’s report on gold-catalyzed direct
acetoxylation of arenes with iodobenzene diacetate, we
considered a one-pot reaction including gold-catalyzed
Hashmi phenol synthesis13 and a subsequent gold-assisted
acetoxylation reaction, as a promising strategy towards ace-
toxylating the phenol systems.
Entry
solvent
Temp Reaction Yield of Yield of
(°C)
time (h) 2a (%)b 3a (%)c
1
2
DCE
80
rt
2
15
15
1
–
–
–
–
–
–
–
5
0
–
47
39
59
56
87
43
0
DCE
3
CHCl3
rt
4
MeCN
rt
In the Hashmi phenol synthesis reaction, AuCl3 in aceto-
nitrile cleanly transformed 1a to 2a within just a few min-
utes. The reactions proceeded at room temperature, neither
air nor water needed to be excluded (Scheme 3).13 Our ini-
tial studies concentrated on the acetoxylation reaction of
the products of the phenol synthesis. These screenings
were performed with test substrate 2a, in the presence of
PhI(OAc)2 and AuCl3 (5 mol%) in dichloroethane (DCE) at 80
°C for 2 hours under air atmosphere (Table 1, entry 1).
During monitoring of the reaction mixture by TLC, we ob-
served that all the substrates of 2a were turned into the
product. After isolation and characterization of the product
by spectroscopic analysis, we found that an unexpected
product 3a was obtained (yield 47%). The structure of the
product 3a was confirmed by spectral and analytical data.
To achieve suitable conditions for synthesis of 3a from 2a,
we tested the reaction under various conditions; the results
are shown in Table 1. As shown in Table 1, the solvents were
found to significantly affect the reaction (entries 1–5).
Whereas the reactivity in dichloroethane as well as in chlo-
roform was in moderate yield after 15 hours at room tem-
perature, we were pleased to find that the use of acetoni-
trile led to 56% of the desired product 3a after 1 hour at
room temperature (entries 2–4).
5
MeCN:H2O (2:1)
MeCN:H2O (2:1)
rt
rt
1
6d
7
1
MeCN:15 mol% aq HCl (2:1) rt
24
1
8e
9e,f
10g
MeCN
rt
rt
rt
12
15
81
MeCN
1
MeCN:H2O (2:1)
1
a Reaction conditions: 2a (1.0 equiv), PhI(OAc)2 (2.0 equiv), AuCl3 (5 mol%),
solvent (6 mL) for 1 mmol of 2a (0.16 M), air.
b Isolated yield based on 1a.
c Isolated yield based on 2a.
d The reaction was carried out in the absence of AuCl3.
e Reaction conditions: 1a (1.0 equiv), PhI(OAc)2 (2.0 equiv), AuCl3 (5 mol%),
MeCN (2 mL).
f PhI(OAc)2: 3.0 equiv.
g Sequential one-pot procedure.
With these promising results in hand, we turned our fo-
cus to the investigation of a one-pot reaction that started
from the corresponding furan–yne system 1a. For this pro-
cedure, 2.0 equivalents of iodobenzene diacetate and 1.0
equivalent of the starting material 1a were mixed in MeCN,
and 5 mol% of AuCl3 was added at room temperature. Un-
fortunately, after 1 hour, the reaction turned out to be unse-
lective, and only a poor yield of the desired product 3a be-
sides minor amounts of intermediate phenol 2a were ob-
tained (Table 1, entry 8), although a complete conversion of
the starting material 1a was monitored.
Besides, an excess amount of iodobenzene diacetate (3.0
equiv) suppressed the formation of the phenol intermediate
2a, but the yield of the desired product 3a did not signifi-
cantly improve (Table 1, entry 9). To circumvent decompo-
sition of the furan–yne substrate 1a, we changed the proto-
col to a sequential one-pot procedure (entry 10). With the
furan–yne substrate 1a, a clean and fast formation of phe-
nol 2a took place within just a few minutes in the presence
of AuCl3. After the complete conversion of the starting ma-
terial was detected by means of thin-layer chromatography,
iodobenzene diacetate and water were added. This proce-
O
AuCl3
PhI(OAc)2
N
Ts
AuCl3
N
Ts
N
Ts
O
Solvent
MeCN
rt
3a
1a
2a
OH
O
Scheme 3 Model reaction
It was also observed that the addition of water to aceto-
nitrile led to an increase in the yield of the product 3a to
87% (Table 1, entry 5). To investigate the effect of gold(III)
catalyst, the reaction was performed in the absence of gold
catalysts and we observed that the yield of the product
dropped conspicuously, indicating tangible role of gold in
this reaction (entry 6). An additional experiment including
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

C
S. Ahmadi, M. Ghanbari
Paper
Synthesis
Table 2 (continued)
Entry Compound
dure led to a highly selective formation of 5-methyl-2-to-
syl-2,3-dihydro-1H-isoindole-4,7-dione (3a) in an excellent
overall yield of 81% (Scheme 4).
Product
Yield (%)
84
O
R2
O
R2
1) AuCl3 (5 mol%), MeCN,
rt, 10 min
O
O
S
O
O
6b
N
S
R1
R1
N
N
S
O
N
S
O
2) PhI(OAc)2 (2.0 equiv), H2O, 1 h
O
O
O
O
1
O
3a: 81%
O
1f
3f
Scheme 4 Cyclization-oxidation sequence for furan–ynes 1
O
O
S
O
S
After optimization of the reaction conditions, to evalu-
ate the general applicability of this sequential one-pot pro-
cedure, a series of furan–yne derivatives 1 were converted
to the corresponding para-benzoquinone derivatives 3un-
der the same reaction conditions. The results are summa-
rized in Table 2. As can be seen from Table 2, the substrates
with additional aromatic substituents 1c–f, showed no loss
of selectivity (Table 2, entries 3–6).
N
N
N
O
N
O
7
8
9
73
O
O
O
1g
1h
3g
O
O
S
O
S
NO2
N
NO2
O
79
86
62
O
O
O
3h
O
Table 2 Scope of the Reactiona
O
S
O
S
OMe
N
OMe
O
O
O
Entry Compound
Product
Yield (%)
81
O
1i
1j
3i
O
O
O
S
O
S
N
N
O
1
O
O
O
O
10
1a
O
3a
O
3j
O
a Reaction conditions: 1a (1.0 equiv), PhI(OAc)2 (2.0 equiv), AuCl3 (5 mol%),
MeCN (2 mL) and H2O (1 mL) (0.16 M), rt, 1 h, air atmosphere.
b Product 3f was obtained at 40 °C.
O
S
O
S
N
N
O
2
3
85
89
O
O
O
1b
1c
3b
Despite the additional aromatic moieties, no trace of
side product was observed even with 2.0 equivalents of io-
dobenzene diacetate. The reaction occurred selectively at
the electron-rich phenol ring. The substrate 1g with ethyl
substituent could also be converted in good overall efficien-
cy (Table 2, entry 7). Switching the substituent at the phe-
nyl ring of furan–yne 1 to an electron-withdrawing nitro
(1h) and electron-donating methoxy groups (1i) delivered a
remarkably overall yield of products (entries 8 and 9).
Changing the heteroatom in the starting material 1 from ni-
trogen to oxygen slightly reduced the yield (entry 10), but
the overall yield of this one-pot protocol was still satisfacto-
ry. All products were characterized by spectral and analyti-
cal data. Unfortunately, all the attempts to obtain single
crystals of these products were unsuccessful.
O
O
S
O
S
N
N
O
O
O
O
3c
O
O
S
4
80
O
S
N
N
O
O
O
O
1d
3d
OMe
OMe
O
O
S
5
86
To evaluate the possibility of further derivatization of
the para-benzoquinone 3, based on Morey’s report,18 the
substrate 3c (1.0 mmol) and sodium dithionate (20.0
mmol) were grounded together at room temperature. Un-
der this condition, the substrate 3c was reduced to the cor-
responding hydroquinone compound 4c in an excellent
O
S
N
N
O
O
O
O
1e
3e
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

D
S. Ahmadi, M. Ghanbari
Paper
Synthesis
OH
R2
R2
O
O
R2
O
O
S
Na2S2O4, rt, 5 h
GP2 or GP3
N-SO2-R1
N
S
R1
NH-SO2-R1
Br
O
N
R1
O
O
GP1
GP2
5
6
O
OH
3
4
GP4
K2CO3
4c
4f R1 = Ph, R2 = Ph, 75%
R
1 = 4-MeC6H4, R2 = Ph, 78%
O
O
acetone
R2
G
Br
Scheme 5 Reduction of benzoquinone to hydroquinone
O
OH
O
NAH, DMF
6j
1
G = N,O
yield. Also, the substrate 3f was converted to hydroquinone
4f under the same reaction condition (Scheme 5).
Scheme 7 Generic routes of preparing the substrate 1
Although the mechanism of this reaction has not been
established experimentally, however, a possible mechanism
for the syntheses of the para-benzoquinones 3 according to
previous chemistry, is proposed in Scheme 6. The first step
of the mechanism involves the formation of phenol deriva-
tives 2 by AuCl3.14 Then oxidation of phenol 2 in the pres-
ence of gold and PhI(OAc)2 leads to the formation of the
para-benzoquinone derivatives 3.19
Iminosulfones 5; General Procedure 1 (GP1)20
Iminosulfones 5 were prepared according to the literature. 5-Methyl-
furfural (1.0 equiv), sulfonamide (1.5 equiv), and Et3N (5.0 equiv)
were dissolved in CH2Cl2 and cooled to 0 °C. Afterwards, TiCl4 (0.5
equiv) in CH2Cl2 was added at that temperature, and allowed to warm
up to r.t with continuous stirring for 30 min (monitoring by TLC). The
mixture was hydrolyzed with sat. aq NaHCO3. The mixture was ex-
tracted with CH2Cl2 (2 ×) and the combined organic layers were
washed with H2O, dried (Na2SO4), and filtered. The solvent was re-
moved under vacuum and the residue was recrystallized.
R2
N
O
R2
N
R2
N
AuCl3
AuCl3
R1
O
Aminosulfones 6; General Procedure 2 (GP2)20
R1
R1
PhI(OAc)2
Aminosulfones 6 were prepared according to the literature. In a
Schlenk flask, the substrate 5 (1.0 equiv) was dissolved in MeOH un-
der N2. Then NaBH4 (1.0 equiv) was added slowly and stirred over-
night. After the slow addition of H2O, the aqueous layer was extracted
with CH2Cl2. The combined organic layers were dried (Na2SO4) and fil-
tered. The solvent was removed under vacuum and the residue was
washed with Et2O.
3
OH
2
O
Scheme 6 Proposed mechanistic pathway
In summary, by using the same gold catalyst for two
subsequent reaction steps, which consist of a furan–yne cy-
clization followed by a gold-assisted oxidation, new para-
benzoquinones are feasible under exceptionally mild reac-
tion conditions and in a one-pot process. Furthermore, the
resulting para-benzoquinones can be readily transformed
into the corresponding hydroquinones through reaction
with sodium dithionate. This reaction may serve as a pow-
erful procedure for the synthesis of other quinone systems.
Addition of Grignard Reagents to Iminosulfones 5; General Proce-
dure 3 (GP 3)14
In a Schlenk flask, the iminosulfone 5 (1.0 equiv) was dissolved in THF
under N2 and cooled to –47 °C. Afterwards, the Grignard reagent (2.0
equiv) was added dropwise and the reaction mixture was stirred for 6
h at –47 °C, allowing to warm up to rt and then stirred overnight. The
reaction was quenched by adding sat. aq NH4Cl. The mixture was ex-
tracted with CH2Cl2 and the combined organic phases were dried
(Na2SO4), filtered, and concentrated under reduced pressure. The
crude product was purified by column chromatography on silica gel
(n-hexane/EtOAc).
All Chemicals were purchased from a commercial supplier (Aldrich,
Merck, Alfa Aesar, and Wako) and were used without further purifica-
tion. TLC analysis was performed using Silicycle precoated TLC plates
(silica gel 60 F254). The products were purified by preparative column
chromatography on silica gel (0.063–0.200 mm; Merck). NMR spectra
were recorded at rt in CDCl3 on 500, 400, and 300 MHz spectrometers.
The chemical shifts for 1H NMR were recorded in ppm downfield from
TMS with CDCl3 (7.26 ppm) as the internal standard. The chemical
shifts for 13C NMR were recorded in ppm downfield using the central
peak of CDCl3 (77.16 ppm) as the internal standard. Coupling con-
stants (J) are reported in hertz (Hz) and refer to apparent peak multi-
plications. IR spectra were recorded on a Magna 550 spectrometer.
EI-MS (70 eV): HP 5973 GC-MS instrument; in m/z. Melting points:
Electrothermal 9200 apparatus. Elemental analyses were performed
with a Thermo Finnigan Flash-1112EA microanalyzer.
Propargylation of Aminosulfones 6; General Procedure 4 (GP 4)14
The aminosulfone 6 was dissolved in acetone, K2CO3 (3.0 equiv) and
propargyl bromide (3.0 equiv., 80% solution in toluene) were added
and the mixture was stirred at rt for 24 h. Then the solvent was re-
moved under vacuum, the residue was partitioned between H2O and
CH2Cl2 and the aqueous phase was extracted with CH2Cl2 (2 ×). The
combined organic phases were dried (Na2SO4), filtered, and concen-
trated under reduced pressure. The crude product was purified by
column chromatography on silica gel (n-hexane/EtOAc).
Gold-Catalyzed Synthesis of para-Benzoquinones 3; General Pro-
cedure 5 (GP 5)
The generic route of preparing the substrate 1 is shown in Scheme 7.
In a dry Schlenk flask, propargylic aminosulfone 1 (1.0 equiv) was
dissolved in anhyd MeCN. The gold catalyst (5 mol%) was added and
the reaction mixture was stirred at rt for 10 min. The progress of the
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

E
S. Ahmadi, M. Ghanbari
Paper
Synthesis
reaction was monitored by TLC and after completion of the first step
of the reaction flask was opened and PhI(OAc)2 (2.0 equiv) and H2O
were added to this mixture. The mixture was stirred for 3 h at rt in air.
After the completion of the reaction, the solvent was removed under
vacuum then the residue extracted with CH2Cl2. The combined organ-
ic layers were dried (Na2SO4), and the solvent was removed in vacu-
um. The product was purified by column chromatography on silica
gel (n-hexane/EtOAc).
N-(5-Methylfuran-2-ylmethyl)benzenesulfonamide (6b)
According to GP 2, 5b (2.50 g, 10.0 mmol) and NaBH4 (0.35 g, 10.0
mmol) in MeOH (12 mL) furnished 6b as a pure pale white solid;
yield: 1.80 g (73%, 7.3 mmol); mp 84–85 °C.
IR (KBr): 3313, 3065, 2922, 1614, 1564, 1441, 1318, 1221, 1156 cm–1
1H NMR (400 MHz, CDCl3):  = 7.82 (d, J = 7.2 Hz, 2 H), 7.56 (t, J = 7.2
Hz, 1 H), 7.48 (t, J = 7.2 Hz, 2 H), 5.94 (s, 1 H), 5.75 (s, 1 H), 4.86 (s, 1
H), 4.15 (d, J = 6.0 Hz, 2 H), 2.11 (s, 3 H).
.
13C NMR (100 MHz, CDCl3):  = 152.2, 147.4, 140.0, 132.5, 128.9,
Reduction of para-Benzoquinones 3; General Procedure 6 (GP 6)18
127.0, 109.1, 106.1, 40.2, 13.3.
MS (EI, 70 eV): m/z (%) = 251 [M+, 100], 174 (80), 156 (55), 141 (40),
110 (35), 95 (65), 77 (75).
para-Benzoquinone 3 (1.0 mmol) and sodium dithionite (20.0 mmol)
were grounded together with the aid of a pestle and mortar. Drastic
color changes were immediately observed. After several hours in an
open vessel, the color completely disappeared. The standard workup
yielded corresponding hydroquinone 4.
Anal. Calcd for C12H13NO3S: C, 57.35; H, 5.21; N, 5.57. Found: C, 57.30;
H, 5.28; N, 5.54.
4-Methyl-N-(5-methylfuran-2-ylmethylene)benzenesulfonamide
4-Methyl-N-[(5-methylfuran-2-yl)(phenyl)methyl]benzenesul-
(5a)20
fonamide (6c)14
According to GP 1, 5-methylfurfural (5.50 g, 50.0 mmol), p-toluene-
sulfonamide (12.84 g, 75.0 mmol), and Et3N (25.30 g, 250.0 mmol) in
CH2Cl2 (165 mL) and TiCl4 (4.74 g, 25.0 mmol) in CH2Cl2 (16.5 mL) fur-
nished 5a as a light orange solid after recrystallization; yield: 11.84 g
(90%, 45.0 mmol); mp 116–117 °C (Lit.20 mp 118–119 °C).
According to GP 3, 5a (1.05 g, 4.0 mmol) and phenylmagnesium bro-
mide (8.0 mL, 8.0 mmol, 1.0 M solution in THF) in THF (15 mL) fur-
nished 6c as a yellow solid after purification by column chromatogra-
phy (eluent: PE/EtOAc 4:1); yield: 1.22 g (90%, 3.6 mmol); mp 109–
110 °C (Lit.14 mp 109 °C).
IR (KBr): 3088, 2923, 1608, 1554, 1450, 1288, 1151 cm–1
.
IR (KBr): 3316, 2920, 1599, 1417, 1327, 1157 cm–1
.
1H NMR (400 MHz, CDCl3):  = 8.69 (s, 1 H), 7.86 (d, J = 8.2 Hz, 2 H),
7.82 (d, J = 3.2 Hz, 1 H), 7.32 (d, J = 8.0 Hz, 2 H), 6.29 (d, J = 3.2 Hz, 1 H),
2.43 (s, 6 H).
1H NMR (400 MHz, CDCl3):  = 7.58 (d, J = 8.0 Hz, 2 H), 7.20–7.24 (m, 5
H), 7.16 (d, J = 8.0 Hz, 2 H), 5.83 (d, J = 2.8 Hz, 1 H), 5.74 (d, J = 1.6 Hz,
1 H), 5.56 (d, J = 7.2 Hz, 1 H), 5.14 (d, J = 7.2 Hz, 1 H), 2.38 (s, 3 H), 2.10
(s, 3 H).
All spectral data are in accordance with previous reports.20
All spectral data are in accordance with previous reports.14
N-(5-Methylfuran-2-ylmethylene)benzenesulfonamide (5b)
According to GP 1, 5-methylfurfural (3.85 g, 35.0 mmol), benzenesul-
fonamide (8.98 g, 52.5 mmol), and Et3N (17.70 g, 175.0 mmol) in
CH2Cl2 (115 mL) and TiCl4 (3.31 g, 17.5 mmol) in CH2Cl2 (11.5 mL) fur-
nished 5b as a bright yellow solid after recrystallization; yield: 4.90 g
(57%, 20.0 mmol); mp 125–126 °C.
4-Methyl-N-[(5-methylfuran-2-yl)(4-methylphenyl)methyl]ben-
zenesulfonamide (6d)14
According to GP 3, 5a (1.57 g, 6.0 mmol) and p-tolylmagnesium bro-
mide (12.0 mL, 12.0 mmol, 1.0 M solution in THF) in THF (20 mL) fur-
nished 6d as a pale yellow solid after purification by column chroma-
tography (eluent: PE/EtOAc 9:1); yield: 1.95 g (92%, 5.5 mmol); mp
109–110 °C (Lit.14 mp 111 °C).
IR (KBr): 3120, 1781, 1604, 1549, 1446, 1322, 1288, 1154 cm–1
.
1H NMR (400 MHz, CDCl3):  = 8.72 (s, 1 H), 7.97–7.99 (m, 2 H), 7.59–
7.62 (m, 1 H), 7.53 (t, J = 8.0 Hz, 2 H), 7.28 (d, J = 3.6 Hz, 1 H), 6.30 (d,
J = 3.6 Hz, 1 H), 2.43 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 162.3, 155.1, 147.6, 138.7, 129.0,
127.8, 111.1, 14.3.
IR (KBr): 3287, 2920, 1916, 1599, 1433, 1329, 1157 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.58 (d, J = 8.0 Hz, 2 H), 7.16 (d, J = 8.0
Hz, 2 H), 7.09 (d, J = 8.0 Hz, 2 H), 7.05 (d, J = 8.0 Hz, 2 H), 5.85 (d, J = 2.8
Hz, 2 H), 5.74 (s, 1 H), 5.52 (d, J = 7.2 Hz, 1 H), 5.20 (d, J = 7.6 Hz, 1 H),
2.38 (s, 3 H), 2.30 (s, 3 H), 2.09 (s, 3 H).
MS (EI, 70 eV): m/z (%) = 249 [M+, 100], 172 (44), 168 (35), 81 (60), 77
(85).
All spectral data are in accordance with previous reports.14
Anal. Calcd for C12H11NO3S: C, 57.82; H, 4.45; N, 5.62. Found: C, 57.78;
H, 4.43; N, 5.60.
N-[(4-Methoxyphenyl)(5-methylfuran-2-yl)methyl]-4-methylben-
zenesulfonamide (6e)21
According to GP 3, 5a (1.31 g, 5.0 mmol) and 4-methoxymagnesium
bromide (10.0 mL, 10.0 mmol, 1.0 M solution in THF) in THF (20 mL)
furnished 6e as a white solid after purification by column chromatog-
raphy (eluent: PE/EtOAc 4:1); yield: 1.67 g (89%, 4.5 mmol); mp 98–
99 °C (Lit.21 mp 101–102 °C).
4-Methyl-N-(5-methylfuran-2-ylmethyl)benzenesulfonamide
(6a)20
According to GP 2, 5a (2.08 g, 8.0 mmol) and NaBH4 (0.28 g, 8.0 mmol)
in MeOH (12 mL) furnished 6a as a pure pale white solid; yield: 1.51 g
(71%, 5.7 mmol); mp 79–80 °C (Lit.20 mp 82–83 °C).
IR (KBr): 3284, 2921, 1612, 1514, 1444, 1324, 1155 cm–1
.
IR (KBr): 3256, 2923, 1590, 1570, 1434, 1321, 1219, 1159 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.57 (d, J = 7.6 Hz, 2 H), 7.16 (d, J = 8.0
Hz, 2 H), 7.11 (d, J = 8.4 Hz, 2 H), 6.76 (d, J = 8.0 Hz, 2 H), 5.83 (s, 1 H),
5.73 (s, 1 H), 5.50 (d, J = 7.2 Hz, 1 H), 5.17 (d, J = 7.2 Hz, 1 H), 3.77 (s, 3
H), 2.38 (s, 3 H), 2.09 (s, 3 H).
1H NMR (400 MHz, CDCl3):  = 7.71 (d, J = 6.0 Hz, 2 H), 7.27 (d, J = 8.4
Hz, 2 H), 5.96 (d, J = 2.8 Hz, 1 H), 5.77 (s, 1 H), 4.72 (s, 1 H), 4.11 (s, 2
H), 2.42 (s, 3 H), 2.13 (s, 3 H).
All spectral data are in accordance with previous reports.20
All spectral data are in accordance with previous reports.21
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

F
S. Ahmadi, M. Ghanbari
Paper
Synthesis
N-[(5-Methylfuran-2-yl)(phenyl)methyl]benzenesulfonamide (6f)
4-Methoxy-N-[(5-methylfuran-2-yl)methyl]benzenesulfonamide
(6i)22
According to GP 3, 5b (2.00 g, 8.0 mmol) and phenylmagnesium bro-
mide (16.0 mL, 16.0 mmol, 1.0 M solution in THF) in THF (25 mL) fur-
nished 6f as a bright yellow solid after purification by column chro-
matography (eluent: PE/EtOAc 4:1); yield: 2.29 g (88%, 7.0 mmol); mp
119–120 °C.
To 5-methylfurfurylamine (2.50 g, 22.5 mmol) and Et3N (2.28 g, 22.5
mmol) in CH2Cl2 (35 mL) at rt was added 4-methoxybenzenesulfonyl
chloride (4.65 g, 22.5 mmol) in small portions and then stirred over-
night. After the slow addition of H2O (30 mL), separation of the organ-
ic layer, extractions of the aqueous layer with CH2Cl2 (2 × 15 mL), the
combined organic layers were dried (Na2SO4) and filtered. The solvent
was removed under vacuum and the residue was purified by column
chromatography on silica gel ( eluent: PE/EtOAc 8:2) to afford 6i as a
white solid; yield: 5.51 g (87%, 19.6 mmol); mp 76–78 °C.
IR (KBr): 3259, 2922, 1562, 1449, 1319, 1161 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.70 (d, J = 7.2 Hz, 2 H), 7.47 (t, J = 7.6
Hz, 2 H), 7.36 (t, J = 7.6 Hz, 2 H), 7.20–7.24 (m, 5 H), 5.83 (d, J = 2.8 Hz,
1 H), 5.73 (d, J = 1.6 Hz, 1 H), 5.59 (d, J = 7.6 Hz, 1 H), 5.30 (d, J = 7.6 Hz,
1 H), 2.09 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 152.3, 150.1, 140.4, 138.3, 132.2,
128.6, 128.4, 127.9, 127.2, 127.0, 109.3, 106.0, 55.6, 13.3.
IR (KBr): 3323, 3055, 2921, 1611, 1560, 1441, 1318, 1222 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.73 (d, J = 8.1 Hz, 2 H), 7.30 (d, J = 8.1
Hz, 2 H), 5.97 (s, 1 H), 5.79 (s, 1 H), 4.70 (s, 1 H), 4.13 (d, J = 5.0 Hz, 2
H), 3.91 (s, 3 H), 2.15 (s, 3 H).
13C NMR (75 MHz, CDCl3):  = 161.8, 152.3, 147.6, 137.0, 124.8, 115.0,
109.1, 106.2, 53.8, 40.3, 13.3.
MS (EI, 70 eV): m/z (%) = 327 [M+, 100], 250 (60), 186 (75), 171 (40),
141 (55), 77 (70).
Anal. Calcd for C18H17NO3S: C, 66.04; H, 5.23; N, 4.28. Found: C, 66.06;
H, 5.26; N, 4.27.
MS (EI, 70 eV): m/z (%) = 281 [M+, 100], 186 (85), 174 (55), 171(55),
107 (70), 95 (60), 81 (55).
4-Methyl-N-[1-(5-methylfuran-2-yl)propyl]benzenesulfonamide
(6g)14
Anal. Calcd for C13H15NO4S: C, 55.50; H, 5.37; N, 4.98. Found: C, 55.48;
H, 5.35; N, 4.95.
According to GP 3, 5a (1.31 g, 5.0 mmol) and ethylmagnesium bro-
mide (10.0 mL, 10.0 mmol, 1.0 M solution in THF) in THF (20 mL) fur-
nished 6g as a white solid after purification by column chromatogra-
phy (eluent: PE/EtOAc 9:1); yield: 1.20 g (82%, 4.1 mmol); mp 77–78
°C (Lit.14 mp 77 °C).
(5-Methylfuran-2-yl)methanol (6j)23
In a flame-dried Schlenk tube under an atmosphere of N2, 5-methyl-
furfural (1.25 g, 11.3 mmol) was dissolved in anhyd MeOH (15 mL).
NaBH4 (0.85 g, 22.7 mmol) was added, and the mixture was stirred for
16 h at rt. H2O was added, and the aqueous phase was extracted with
CH2Cl2. The combined organic layers were dried (Na2SO4) and filtered.
Evaporation of the solvent afforded 6j as an orange oil. The crude
product was used in the next step without further purification; yield:
1.18 g (94%, 10.6 mmol).
IR (KBr): 3256, 3111, 2921, 2855, 1598, 1434, 1321, 1160, 1094, 1042
cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.62 (t, J = 8.4 Hz, 2 H), 7.20 (t, J = 8.0
Hz, 2 H), 5.80 (d, J = 6.8 Hz, 1 H), 5.67 (d, J = 6.8 Hz, 1 H), 4.76 (t, J = 8.4
Hz, 1 H), 4.25 (t, J = 8.0 Hz, 1 H), 2.39 (d, J = 9.2 Hz, 3 H), 2.05 (d, J = 9.2
Hz, 3 H), 1.78 (q, J = 8.0 Hz, 2 H), 0.86 (q, J = 8.0 Hz, 3 H).
IR (KBr): 3406, 2960, 2940, 2880, 1556, 1442, 1085, 1020 cm–1
1H NMR (400 MHz, CDCl3):  = 6.14 (d, J = 3.0 Hz, 1 H), 5.90 (d, J = 3.0
.
All spectral data are in accordance with previous reports.14
Hz, 1 H), 4.51 (s, 2 H), 2.33 (s, 1 H), 2.26 (s, 3 H).
All spectral data are in accordance with previous reports.23
N-[(5-Methylfuran-2-yl)methyl]-4-nitrobenzenesulfonamide
(6h)22
To 5-methylfurfurylamine (2.50 g, 22.5 mmol) and Et3N (2.28 g, 22.5
mmol) in CH2Cl2 (35 mL) at rt was added nosyl chloride (4.98 g, 22.5
mmol) in small portions and then stirred overnight. After the slow
addition of H2O (30 mL), separation of the organic layer, extractions of
the aqueous layer with CH2Cl2 (2 × 15 mL), the combined organic lay-
ers were dried (Na2SO4) and filtered. The solvent was removed under
vacuum and the residue was purified by column chromatography on
silica gel (eluent: PE/EtOAc, 8:2) to afford 6h as a yellow solid; yield:
5.54 g (83%, 18.7 mmol); mp 93–95 °C.
4-Methyl-N-[(5-methylfuran-2-yl)methyl]-N-(prop-2-yne-1-
yl)benzenesulfonamide (1a)20
According to GP 4, 6a (2.60 g, 10.0 mmol), K2CO3 (2.70 g, 20.0 mmol),
and propargyl bromide (2.38 g, 20.0 mmol, 80% solution in toluene)
in acetone (18 mL) furnished 1a as a pale white solid after purifica-
tion by column chromatography (eluent: PE/EtOAc 9:1); yield: 2.88 g
(95%, 9.5 mmol); mp 69–70 °C (Lit.20 mp 68–71 °C).
IR (KBr): 3277, 2923, 2118, 1596, 1430, 1159 cm–1
.
IR (KBr): 3311, 3059, 2920, 1617, 1562, 1444, 1321, 1220 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.74 (d, J = 8.4 Hz, 2 H), 7.29 (d, J = 8.0
Hz, 2 H), 6.16 (s, 1 H), 5.87 (s, 1 H), 4.38 (s, 2 H), 4.02 (s, 2 H), 2.43 (s, 3
H), 2.21 (s, 3 H), 2.06 (s, 1 H).
1H NMR (400 MHz, CDCl3):  = 8.38 (d, J = 8.2 Hz, 2 H), 7.95 (d, J = 8.2
Hz, 2 H), 5.98 (d, J = 3.0 Hz, 1 H), 5.86 (d, J = 3.0 Hz, 1 H), 4.73 (m, 1 H),
4.16 (d, J = 6.0 Hz, 2 H), 2.12 (s, 3 H).
All spectral data are in accordance with previous reports.20
13C NMR (75 MHz, CDCl3):  = 152.2, 150.3, 146.6, 137.7, 129.2, 124.7,
109.2, 106.0, 44.3, 13.3.
MS (EI, 70 eV): m/z (%) = 296 [M+, 100], 185 (75), 174 (65), 122(40),
N-[(5-Methylfuran-2-yl)methyl]-N-(prop-2-yne-1-yl)benzenesul-
fonamide (1b)
110 (45), 95 (50), 81 (65).
According to GP 4, 6b (3.00 g, 12.0 mmol), K2CO3 (3.30 g, 24.0 mmol),
and propargyl bromide (2.85 g, 24.0 mmol, 80% solution in toluene)
in acetone (20 mL) furnished 1b as a pale-yellow solid after purifica-
tion by column chromatography (eluent: PE/EtOAc 9:1); yield: 3.29 g
(95%, 11.4 mmol); mp 69–70 °C.
Anal. Calcd for C12H12N2O5S: C, 48.64; H, 4.08; N, 9.45. Found: C,
48.66; H, 4.09; N, 9.43.
IR (KBr): 3288, 3065, 2922, 2120, 1478, 1350, 1163 cm–1
.
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

G
S. Ahmadi, M. Ghanbari
Paper
Synthesis
1H NMR (500 MHz, CDCl3):  = 7.85 (d, J = 7.0 Hz, 2 H), 7.57 (t, J = 7.5
Hz, 1 H), 7.49 (t, J = 8.0 Hz, 2 H), 6.15 (s, 1 H), 5.85 (s, 1 H), 4.39 (s, 2
H), 4.03 (s, 2 H), 2.19 (s, 3 H), 2.04 (s, 1 H).
Anal. Calcd for C23H23NO4S: C, 67.46; H, 5.66; N, 3.42. Found: C, 67.43;
H, 5.64; N, 3.40.
13C NMR (100 MHz, CDCl3):  = 152.8, 146.3, 139.0, 132.7, 128.8,
N-[(5-Methylfuran-2-yl)(phenyl)methyl]-N-(prop-2-yne-1-yl)ben-
zenesulfonamide (1f)
127.7, 111.1, 106.3, 76.4, 73.8, 42.9, 36.0, 13.5.
MS (EI, 70 eV): m/z (%) = 289 [M+, 100], 212 (40), 194 (45), 148 (60),
141 (75), 77 (80).
According to GP 4, 6f (1.30 g, 4.0 mmol), K2CO3 (1.65 g, 12.0 mmol),
and propargyl bromide (1.08 g, 10.0 mmol, 80% solution in toluene)
in acetone (10 mL) furnished 1f as a yellow oil after purification by
column chromatography (eluent: PE/EtOAc 9:1); yield: 1.24 g (85%,
3.4 mmol).
Anal. Calcd for C15H15NO3S: C, 62.27; H, 5.23; N, 4.84. Found: C, 62.30;
H, 5.21; N, 4.80.
IR (KBr): 3290, 3063, 2922, 2122, 1605, 1447, 1346, 1219, 1162 cm–1
.
4-Methyl-N-[(5-methylfuran-2-yl)(phenyl)methyl]-N-(prop-2-
1H NMR (400 MHz, CDCl3):  = 7.91 (d, J = 7.2 Hz, 2 H), 7.54 (d, J = 7.2
Hz, 2 H), 7.45 (t, J = 8.0 Hz, 2 H), 7.32 (m, 5 H), 6.31 (s, 1 H), 5.96 (d, J =
2.8 Hz, 1 H), 5.83 (d, J = 2.0 Hz, 2 H), 5.30 (s, 1 H), 4.20 (dd, J = 18.4, 2.4
Hz, 1 H), 3.95 (dd, J = 18.4, 2.4 Hz, 1 H), 2.11 (s, 3 H), 1.87 (t, J = 2.4 Hz,
1 H).
13C NMR (100 MHz, CDCl3):  = 152.3, 148.9, 140.1, 136.6, 132.4,
128.4, 128.4, 128.0, 127.9, 127.9, 111.7, 106.1, 78.5, 71.6, 58.8, 34.6,
13.4.
yne-1-yl)benzenesulfonamide (1c)14
According to GP 4, 6c (1.70 g, 5.0 mmol), K2CO3 (1.38 g, 10.0 mmol),
and propargyl bromide (1.08 g, 10.0 mmol, 80% solution in toluene)
in acetone (10 mL) furnished 1c as a bright yellow oil after purifica-
tion by column chromatography (eluent: PE/EtOAc 9:1); yield: 1.78 g
(94%, 4.7 mmol).
IR (KBr): 3292, 3030, 2923, 2122, 1599, 1449, 1345, 1218, 1160 cm–1
.
1H NMR (500 MHz, CDCl3):  = 7.79 (d, J = 8.4 Hz, 2 H), 7.32 (m, 6 H),
7.25 (d, J = 8.0 Hz, 2 H), 6.30 (s, 1 H), 5.97 (d, J = 2.8 Hz, 2 H), 5.84 (s, 1
H), 4.18 (dd, J = 18.4, 2 Hz, 1 H), 3.94 (dd, J = 18.4, 2 Hz, 1 H), 2.42(s, 3
H), 2.12 (s, 3 H), 1.90 (s, 1 H).
MS (EI, 70 eV): m/z (%) = 365 [M+, 90], 288 (65), 224 (55), 194 (35),
141 (60), 77 (100).
Anal. Calcd for C21H19NO3S: C, 69.02; H, 5.24; N, 3.83. Found: C, 68.98;
H, 5.22; N, 3.82.
All spectral data are in accordance with previous reports.14
4-Methyl-N-[1-(5-methylfuran-2-yl)propyl]-N-(prop-2-yne-1-
4-Methyl-N-[(5-methylfuran-2-yl)(4-methylphenyl)methyl]-N-
yl)benzenesulfonamide (1g)14
(prop-2-yne-1-yl)benzenesulfonamide (1d)14
According to GP 4, 6g (1.46 g, 5.0 mmol), K2CO3 (2.07 g, 15.0 mmol),
and propargyl bromide (1.08 g, 10.0 mmol, 80% solution in toluene)
in acetone (10 mL) furnished 1g as a pale red oil after purification by
column chromatography (eluent: PE/EtOAc 9:1); yield: 1.42 g (85%,
4.3 mmol).
According to GP 4, 6d (1.42 g, 4.0 mmol), K2CO3 (1.65 g, 12.0 mmol),
and propargyl bromide (1.08 g, 10.0 mmol, 80% solution in toluene)
in acetone (10 mL) furnished 1d as a white solid after purification by
column chromatography (eluent: PE/EtOAc 9:1); yield: 1.41 g (91%,
3.6 mmol); mp 99–100 °C (Lit.14 mp 101 °C).
IR (KBr): 3275, 2924, 2119, 1597, 1431, 1158, 1115, 1094 cm–1
.
IR (KBr): 3296, 2922, 2120, 1597, 1413, 1329, 1157 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.81 (d, J = 7.2 Hz, 2 H), 7.27 (d, J = 7.2
Hz, 2 H), 6.00 (s, 1 H), 5.79 (s, 1 H), 4.89 (t, J = 7.2 Hz, 1 H), 3.95 (d, J =
18.4 Hz, 1 H), 3.76 (d, J = 18.4 Hz, 1 H), 2.42 (s, 3 H), 2.04 (s, 3 H), 2.01
(s, 1 H), 1.96–2.02 (q, J = 7.2 Hz, 2 H), 1.01 (t, J = 7.2 Hz, 3 H).
1H NMR (400 MHz, CDCl3):  = 7.79 (d, J = 8.0 Hz, 2 H), 7.24 (d, J = 8.0
Hz, 2 H), 7.21 (d, J = 8.0 Hz, 2 H), 7.13 (d, J = 8.0 Hz, 2 H), 6.25 (s, 1 H),
5.97 (d, J = 2.8 Hz, 1 H), 5.84 (s, 1 H), 4.18 (dd, J = 18.4, 2.4 Hz, 1 H),
3.93 (dd, J = 18.4, 2.4 Hz, 1 H), 2.42 (s, 3 H), 2.34 (s, 3 H), 2.12 (s, 3 H),
1.90 (s, 1 H).
All spectral data are in accordance with previous reports.14
All spectral data are in accordance with previous reports.14
N-[(5-Methylfuran-2-yl)methyl]-4-nitro-N-(prop-2-yn-1-yl)ben-
zenesulfonamide (1h)
N-[(4-Methoxyphenyl)(5-methylfuran-2-yl)methyl]-4-methyl-N-
According to GP 4, 6h (3.55 g, 12.0 mmol), K2CO3 (3.30 g, 24.0 mmol),
and propargyl bromide (2.85 g, 24.0 mmol, 80% solution in toluene)
in acetone (20 mL) furnished 1h as a yellow solid after purification by
column chromatography (eluent: PE/EtOAc 8:2); yield: 3.64 g (91%,
10.9 mmol); mp 81–83 °C.
(prop-2-yne-1-yl)benzenesulfonamide (1e)
According to GP 4, 6e (1.85 g, 5.0 mmol), K2CO3 (2.07 g, 15.0 mmol),
and propargyl bromide (1.08 g, 10.0 mmol, 80% solution in toluene)
in acetone (10 mL) furnished 1e as a yellow oil after purification by
column chromatography (eluent: PE/EtOAc 9:1); yield: 1.92 g (93%,
4.7 mmol).
IR (KBr): 3293, 2921, 2120, 1595, 1414, 1338, 1156 cm–1
.
IR (KBr): 3288, 2923, 2121, 1609, 1457, 1250, 1160 cm–1
.
1H NMR (400 MHz, CDCl3):  = 8.36 (d, J = 8.2 Hz, 2 H), 7.90 (d, J = 8.2
Hz, 2 H), 6.15 (s, 1 H), 5.86 (s, 1 H), 4.38 (s, 2 H), 4.02 (d, J = 3.0 Hz, 2
H), 2.20 (s, 3 H), 2.06 (t, J = 3.0 Hz, 1 H).
13C NMR (75 MHz, CDCl3):  = 151.7, 150.1, 142.9, 137.8, 129.1, 127.8,
112.0, 107.9, 79.6, 71.5, 46.5, 33.5, 13.3.
1H NMR (400 MHz, CDCl3):  = 7.77 (d, J = 8.0 Hz, 2 H), 7.24 (d, J = 8.4
Hz, 4 H), 6.84 (d, J = 8.4 Hz, 2 H), 6.23 (s, 1 H), 5.97 (d, J = 3.2 Hz, 1 H),
5.83 (d, J = 3.2 Hz, 1 H), 4.19 (dd, J = 18.4, 2.4 Hz, 1 H), 3.97 (dd, J =
18.4, 2.4 Hz, 1 H), 3.80 (s, 3 H), 2.42 (s, 3 H), 2.12 (s, 3 H),1.91 (s, 1 H).
13C NMR (100 MHz, CDCl3):  = 159.3, 152.1, 149.2, 143.2, 137.1,
129.6, 129.4, 129.1, 128.6, 127.8, 127.3, 111.4, 106.5, 78.9, 71.7, 55.2,
34.4, 21.5, 13.4.
MS (EI, 70 eV): m/z (%) = 334 [M+, 100], 295 (70), 239 (65), 212 (40),
194 (35), 122 (75), 116 (60), 95 (80).
Anal. Calcd for C15H14N2O5S: C, 53.89; H, 4.22; N, 8.38. Found: C,
53.85; H, 4.20; N, 8.37.
MS (EI, 70 eV): m/z (%) = 409 [M+, 90], 328 (75), 318 (45), 254 (80),
208 (75), 155 (55), 91 (100).
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

H
S. Ahmadi, M. Ghanbari
Paper
Synthesis
4-Methoxy-N-[(5-methylfuran-2-yl)methyl]-N-(prop-2-yn-1-
5-Methyl-2-(phenylsulfonyl)-2,3-dihydro-1H-isoindole-4,7-dione
yl)benzenesulfonamide (1i)
(3b)
According to GP 4, 6i (3.37 g, 12.0 mmol), K2CO3 (3.30 g, 24.0 mmol),
and propargyl bromide (2.85 g, 24.0 mmol, 80% solution in toluene)
in acetone (20 mL) furnished 1i as a white solid after purification by
column chromatography (eluent: PE/EtOAc 8:2); yield: 3.60 g (94%,
11.3 mmol); mp 72–74 °C.
The reaction was carried out according to GP 5: 1b (0.14 g, 0.50
mmol, 1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4
mL) and PhI(OAc)2 (0.32 g, 1.0 mmol, 2.0 equiv) in H2O (2 mL). Com-
pound 3b was obtained as a pale yellow solid after column chroma-
tography (eluent: n-hexane/EtOAc 8:2); yield: 0.12 g (85%, 0.42
mmol); Rf = 0.55 (n-hexane/EtOAc 8:2); mp 150–151 °C.
IR (KBr): 3285, 2921, 2120, 1611, 1456, 1248, 1161 cm–1
.
IR (KBr): 2924, 1658, 1610, 1445, 1351, 1164 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.78 (d, J = 6.9 Hz, 2 H), 7.25 (d, J = 6.9
Hz, 2 H), 6.17 (s, 1 H), 5.81 (s, 1 H), 4.35 (s, 2 H), 3.98 (s, 2 H), 3.90 (s, 3
H), 2.19 (s, 3 H), 1.97 (t, J = 3.0 Hz, 1 H).
1H NMR (500 MHz, CDCl3):  = 7.86 (d, J = 7.5 Hz, 2 H), 7.62 (t, J = 7.0
Hz, 1 H), 7.55 (t, J = 7.0 Hz, 2 H), 6.51 (s, 1 H), 4.51 (s, 4 H), 2.02 (s, 3
H).
13C NMR (75 MHz, CDCl3):  = 160.0, 152.2, 143.2, 137.7, 125.1, 116.2,
111.5, 106.1, 78.8, 73.5, 52.7, 42.8, 34.5, 13.5.
13C NMR (100 MHz, CDCl3):  = 183.6, 183.2, 146.4, 142.0, 141.8,
136.5, 133.2, 129.5, 127.4, 53.1, 52.9, 15.4.
MS (EI, 70 eV): m/z (%) = 303 [M+, 100], 226 (65), 162 (40), 141 (45),
MS (EI, 70 eV): m/z (%) = 319 [M+, 100], 280 (70), 224 (45), 212 (55),
107 (65), 95 (85).
77 (80).
Anal. Calcd for C16H17NO4S: C, 60.17; H, 5.37; N, 4.39. Found: C, 60.20;
H, 5.38; N, 4.41.
Anal. Calcd for C15H13NO4S: C, 59.40; H, 4.32; N, 4.62. Found: C, 59.51;
H, 4.28; N, 4.66.
(Methylfuran-2-yl)methanol (1j)23
5-Methyl-1-phenyl-2,3-dihydro-1H-isoindole-4,7-dione (3c)
In a three-necked flask under an atmosphere of N2, alcohol 6j (5.0
mmol, 1.0 equiv) was dissolved in anhyd DMF (20 mL) and cooled to 0
°C. NaH (2.0 equiv, 60% dispersion in mineral oil) was added slowly.
After stirring for 15 min at 0 °C, propargyl bromide (2.0 equiv, 80% in
toluene) was added. The mixture was stirred for 16 h at rt. H2O was
added, and the product was extracted with CH2Cl2. The combined or-
ganic layers were dried (Na2SO4) and the solvent was evaporated. The
crude product was purified by column chromatography on silica gel
(eluent: PE/EtOAc 9:1) to yield 1j as a yellow oil; yield: 0.69 g (92%, 4.6
mmol).
The reaction was carried out according to GP 5: 1c (0.22 g, 0.60 mmol,
1.0 equiv), AuCl3 (9 mg, 0.03 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.38 g, 1.2 mmol, 2.0 equiv) in H2O (2 mL). Compound
3c was obtained as a light green solid after column chromatography
(eluent: n-hexane/EtOAc 8:2); yield: 0.20 g (89%, 0.53 mmol); Rf =
0.60 (n-hexane/EtOAc 8:2); mp 130–131 °C.
IR (KBr): 3063, 2924, 1663, 1602, 1454, 1342, 1160 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.46 (d, J = 8.0 Hz, 2 H), 7.26–7.27 (m, 5
H), 7.17 (d, J = 8.0 Hz, 2 H), 6.42 (s, 1 H), 5.99 (dd, J = 5.6, 2.4 Hz, 1 H),
4.74 (dd, J = 17.2, 2.4 Hz, 1 H), 4.61 (dd, J = 17.2, 6.0 Hz, 1 H), 2.38 (s, 3
H), 2.02 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 184.3, 182.7, 145.9, 144.0, 143.7,
140.9, 138.0, 135.2, 133.7, 129.6, 128.5, 128.4, 127.5, 127.1, 68.9, 52.7,
21.4, 15.3.
IR (KBr): 3295, 2958, 2922, 2129, 1551, 1444, 1221, 1061, 927 cm–1
.
1H NMR (400 MHz, CDCl3):  = 6.24 (d, J = 3.0 Hz, 1 H), 5.92–5.95 (m, 1
H), 4.49 (s, 2 H), 4.15 (d, J = 2.4 Hz, 2 H), 2.46 (t, J = 2.4 Hz, 1 H), 2.29 (s,
3 H).
All spectral data are in accordance with previous reports.23
MS (EI, 70 eV): m/z (%) = 393 [M+, 100], 316 (75), 302 (50), 238 (45),
161 (60), 91 (80), 77 (75).
5-Methyl-2-tosyl-2,3-dihydro-1H-isoindole-4,7-dione (3a)
The reaction was carried out according to GP 5: 1a (0.15 g, 0.50 mmol,
1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.32 g 1.0 mmol, 2.0 equiv) in H2O (2 mL). Compound
3a was obtained as a green solid after column chromatography (elu-
ent: n-hexane/EtOAc 8:2); yield: 0.12 g (81%, 0.40 mmol); Rf = 0.66 (n-
hexane/EtOAc 8:2); mp 186–187 °C.
Anal. Calcd for C22H19NO4S: C, 67.16; H, 4.87; N, 3.56. Found: C, 67.10;
H, 4.84; N, 3.51.
5-Methyl-1-(p-tolyl)-2,3-dihydro-1H-isoindole-4,7-dione (3d)
The reaction was carried out according to GP 5: 1d (0.18 g, 0.47
mmol, 1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4
mL) and PhI(OAc)2 (0.30 g, 0.94 mmol, 2.0 equiv) in H2O (2 mL). Com-
pound 3d was obtained as a yellow solid after column chromatogra-
phy (eluent: n-hexane/EtOAc 8:2); yield: 0.15 g (80%, 0.37 mmol); Rf =
0.58 (n-hexane/EtOAc 8:2); mp 145–146 °C.
IR (KBr): 2924, 1658, 1608, 1457, 1348, 1162 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.73 (d, J = 10.8 Hz, 2 H), 7.33 (d, J =
10.8 Hz, 2 H), 6.50 (d, J = 2.4 Hz, 1 H), 4.48 (s, 4 H), 2.41 (s, 3 H), 2.01
(s, 3 H).
13C NMR (100 MHz, CDCl3):  = 183.6, 183.2, 146.4, 144.2, 142.0,
141.8, 133.4, 133.2, 130.0, 127.4, 53.0, 52.9, 21.5, 15.4. DEPT: 133.3,
130.1, 127.5, 53.0, 21.5, 15.4.
MS (EI, 70 eV): m/z (%) = 317 [M+, 100], 226 (70), 162 (55), 155 (65),
91 (90).
IR (KBr): 2922, 1660, 1601, 1454, 1343, 1161 cm–1
.
1H NMR (500 MHz, CDCl3):  = 7.47 (d, J = 8.0 Hz, 2 H), 7.16 (d, J = 8.0
Hz, 2 H), 7.13 (d, J = 7.5 Hz, 2 H), 7.05 (d, J = 7.5 Hz, 2 H), 6.40 (s, 1 H),
5.94 (d, J = 5.5 Hz, 1 H), 4.71 (dd, J = 17.0, 2.0 Hz, 1 H), 4.60 (dd, J =
17.5, 5.5 Hz, 1 H), 2.37 (s, 3 H), 2.30 (s, 3 H), 2.01 (s, 3 H).
Anal. Calcd for C16H15NO4S: C, 60.55; H, 4.76; N, 4.41. Found: C, 60.23;
H, 4.71; N, 4.35.
13C NMR (100 MHz, CDCl3):  = 184.4, 182.8, 167.7, 145.9, 143.6,
138.3, 135.1, 130.8, 129.5, 129.2, 128.7, 127.4, 127.2, 68.7, 52.6, 21.4,
21.1, 15.3.
MS (EI, 70 eV): m/z (%) = 407 [M+, 100], 316 (80), 168 (55), 252 (60),
91 (90).
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

I
S. Ahmadi, M. Ghanbari
Paper
Synthesis
Anal. Calcd for C23H21NO4S: C, 67.79; H, 5.19; N, 3.44. Found: C, 67.71;
H, 5.16; N, 3.40.
MS (EI, 70 eV): m/z (%) = 345 [M+, 100], 316 (60), 254 (65), 190 (55),
91 (75).
Anal. Calcd for C18H19NO4S: C, 62.59; H, 5.54; N, 4.06. Found: C, 62.53;
H, 5.51; N, 4.03.
1-(4-Methoxyphenyl)-5-methyl-2-tosyl-2,3-dihydro-1H-isoin-
dole-4,7-dione (3e)
The reaction was carried out according to GP 5: 1e (0.28 g, 0.70 mmol,
1.0 equiv), AuCl3 (9 mg, 0.03 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.45 g, 1.4 mmol, 2.0 equiv) in H2O (2 mL). Compound
3e was obtained as a light green solid after column chromatography
(eluent: n-hexane/EtOAc 8:2); yield: 0.25 g (86%, 0.60 mmol); Rf =
0.55 (n-hexane/EtOAc 8:2); mp 122–123 °C.
5-Methyl-2-[(4-nitrophenyl)sulfonyl]-2,3-dihydro-1H-isoindole-
4,7-dione (3h)
The reaction was carried out according to GP 5: 1h (0.17 g, 0.50
mmol, 1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4
mL), PhI(OAc)2 (0.32 g, 1.0 mmol, 2.0 equiv), and H2O (2 mL). Com-
pound 3h was obtained as a green solid after column chromatography
(eluent: n-hexane/EtOAc 8:2); yield: 0.13 g (79%, 0.39 mmol); Rf =
0.54 (n-hexane/EtOAc 8:2); mp 192–194 °C.
IR (KBr): 2925, 1661, 1607, 1439, 1343, 1160 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.46 (d, J = 7.6 Hz, 2 H), 7.15–7.19 (m, 4
H), 6.78 (d, J = 8.0 Hz, 2 H), 6.42 (s, 1 H), 5.96 (s, 1 H), 4.71 (d, J = 16.8
Hz, 1 H), 4.59 (dd, J = 16.8, 5.6 Hz, 1 H), 3.79 (s, 3 H), 2.38 (s, 3 H), 2.02
(s, 3 H).
13C NMR (100 MHz, CDCl3):  = 184.4, 182.8, 159.6, 145.9, 144.0,
143.6, 140.6, 135.3, 133.6, 130.1, 129.6, 128.7, 127.1, 113.9, 68.4, 55.2,
52.5, 21.4, 15.3.
IR (KBr): 2967, 2925, 1657, 1611, 1444, 1347, 1161 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.34 (d, J = 9.1 Hz, 2 H), 7.97 (d, J = 9.1
Hz, 2 H), 6.51 (s, 1 H), 4.54 (s, 4 H), 2.02 (s, 3 H).
13C NMR (75 MHz, CDCl3):  = 184.1, 183.3, 151.9, 148.3, 146.3, 143.6,
138.1, 133.6, 129.8, 127.1, 54.1, 53.7, 15.2.
MS (EI, 70 eV): m/z (%) = 348 [M+, 100], 226 (70), 185 (85), 162 (50),
122 (75).
MS (EI, 70 eV): m/z (%) = 423 [M+, 100], 332 (65), 268 (45), 107 (75),
91 (80).
Anal. Calcd for C15H12N2O6S: C, 51.72; H, 3.47; N, 8.04. Found: C,
51.75; H, 3.46; N, 8.04.
Anal. Calcd for C23H21NO5S: C, 65.23; H, 5.00; N, 3.31. Found: C, 65.27;
H, 5.03; N, 3.28.
2-[(4-Methoxyphenyl)sulfonyl]-5-methyl-2,3-dihydro-1H-isoin-
dole-4,7-dione (3i)
5-Methyl-1-phenyl-2-(phenylsulfonyl)-2,3-dihydro-1H-isoindole-
4,7-dione (3f)
The reaction was carried out according to GP 5: 1i (0.16 g, 0.50 mmol,
1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.32 g, 1.0 mmol, 2.0 equiv) in H2O (2 mL). Compound
3i was obtained as a yellow solid after column chromatography (elu-
ent: n-hexane/EtOAc 8:2); yield: 0.14 g (86%, 0.43 mmol); Rf = 0.61 (n-
hexane/EtOAc 8:2); mp 170–173 °C.
The reaction was carried out according to GP 5: 1f (0.21 g, 0.60 mmol,
1.0 equiv), AuCl3 (9 mg, 0.03 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.38 g, 1.2 mmol, 2.0 equiv) in H2O (2 mL). Compound
3f was obtained as a yellow solid after column chromatography (elu-
ent: n-hexane/EtOAc 8:2); yield: 0.18 g (84%, 0.50 mmol); Rf = 0.60 (n-
hexane/EtOAc 8:2); mp 107–108 °C.
IR (KBr): 2921, 1663, 16010, 1440, 1344, 1158 cm–1
.
IR (KBr): 3063, 2924, 1660, 1596, 1448, 1345, 1164, 1098 cm–1
.
1H NMR (300 MHz, CDCl3):  = 7.73 (d, J = 6.9 Hz, 2 H), 7.36 (d, J = 6.9
Hz, 2 H), 6.50 (d, J = 2.8 Hz, 1 H), 4.46 (s, 4 H), 3.91 (s, 3 H), 2.00 (s, 3
H).
13C NMR (75 MHz, CDCl3):  = 183.6, 182.4, 159.7, 146.2, 143.5, 141.4,
133.8, 131.8, 127.2, 117.8, 55.3, 53.3, 52.1, 15.1.
MS (EI, 70 eV): m/z (%) = 333 [M+, 100], 226 (75), 171 (50), 162 (55),
107 (80).
1H NMR (400 MHz, CDCl3):  = 7.54 (d, J = 7.6 Hz, 2 H), 7.48 (d, J = 7.2
Hz, 2 H), 7.35 (t, J = 7.6 Hz, 3 H), 7.23–7.26 (m, 5 H), 6.42 (s, 1 H), 6.02
(s, 1 H), 4.77 (dd, J = 16.8, 2.0 Hz, 1 H), 4.59 (dd, J = 16.8, 6.0 Hz, 1 H),
2.02 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 184.3, 182.6, 146.0, 144.0, 140.8,
138.3, 137.7, 133.6, 132.7, 131.2, 129.0, 128.6, 127.5, 126.9, 68.9, 52.7,
15.3.
Anal. Calcd for C16H15NO5S: C, 57.65; H, 4.54; N, 4.20. Found: C, 57.63;
H, 4.53; N, 4.19.
MS (EI, 70 eV): m/z (%) = 379 [M+, 100], 302 (65), 238 (50), 141 (45),
77 (95).
Anal. Calcd for C21H17NO4S: C, 66.48; H, 4.52; N, 3.69. Found: C, 66.42;
H, 4.50; N, 3.65.
5-Methyl-1,3-dihydroisobenzofuran-4,7-dione (3j)
The reaction was carried out according to GP 5: 1j (0.075 g, 0.50
mmol, 1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4
mL) and PhI(OAc)2 (0.32 g, 1.0 mmol, 2.0 equiv) in H2O (2 mL). Com-
pound 3j was obtained as a white solid after column chromatography
(eluent: n-hexane/EtOAc 8:2); yield: 0.05 g (62%, 0.31 mmol); Rf =
0.41 (n-hexane/EtOAc 9:1); mp 192–194 °C.
1-Ethyl-5-methyl-2-tosyl-2,3-dihydro-1H-isoindole-4,7-dione (3g)
The reaction was carried out according to GP 5: 1g (0.18 g, 0.55 mmol,
1.0 equiv), AuCl3 (6 mg, 0.02 mmol, 5 mol%) in anhyd MeCN (4 mL)
and PhI(OAc)2 (0.35 g, 1.10 mmol, 2.0 equiv) in H2O (2 mL). Com-
pound 3g was obtained as a light red oil after column chromatogra-
phy (eluent: n-hexane/EtOAc 9:1); yield: 0.13 g (73%, 0.40 mmol); Rf =
0.52 (n-hexane/EtOAc 9:1).
IR (KBr): 2920, 2859, 1661, 1627, 1421, 1233 cm–1
.
1H NMR (300 MHz, CDCl3):  = 6.56 (s, 1 H), 5.05 (s, 4 H), 2.09 (s, 3 H).
13C NMR (75 MHz, CDCl3):  = 187.4, 186.2, 154.1, 153.2, 139.1, 132.6,
IR (KBr): 2969, 2930, 1659, 1608, 1453, 1348, 1162 cm–1
.
76.1, 75.1, 15.0.
1H NMR (500 MHz, CDCl3):  = 7.71 (d, J = 8.5 Hz, 2 H), 7.30 (d, J = 8.0
Hz, 2 H), 6.45 (s, 1 H), 5.02 (s, 1 H), 4.45 (t, J = 3.0 Hz, 2 H), 2.40 (s, 3
H), 2.00 (s, 3 H), 1.09 (q, J = 7.5 Hz, 2 H), 0.82 (t, J = 7.5 Hz, 3 H).
MS (EI, 70 eV): m/z (%) = 164 [M+, 100], 150 (75), 120 (60), 106 (50).
Anal. Calcd for C9H8O3: C, 65.85; H, 4.91. Found: C, 65.83; H, 4.90.
13C NMR (100 MHz, CDCl3):  = 146.1, 143.8, 142.0, 138.4, 134.3,
130.5, 130.0, 127.5, 127.3, 67.1, 53.1, 26.9, 21.5, 15.2, 7.9.
© 2020. Thieme. All rights reserved. Synthesis 2020, 52, A–J

J
S. Ahmadi, M. Ghanbari
Paper
Synthesis
5-Methyl-1-phenyl-2-tosylisoindoline-4,7-diol (4c)
(4) Shrestha, J. P.; Subedi, Y. P.; Chen, L.; Chang, C.-W. T. MedChem-
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Rudolph, M.; Rominger, F.; Hashmi, A. S. K. Adv. Synth. Catal.
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thesis of Heterocyclic Compounds, In Au-Catalyzed Synthesis and
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Eur. J. 2012, 18, 8113.
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S. K.; Ng, S. W. J. Iran. Chem. Soc. 2016, 13, 7. (c) Kianmehr, E.;
Ghanbari, M. Eur. J. Org. Chem. 2012, 256. (d) Ghanbari, M.;
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The reaction was carried out according to GP 6 with 3c (0.07 g, 0.20
mmol, 1.0 equiv) and sodium dithionite (0.82 g, 4.0 mmol, 20.0
equiv). Compound 4c was obtained as a light brown solid after col-
umn chromatography (eluent: n-hexane/EtOAc 8:2); yield: 0.05 g
(78%, 0.15 mmol); Rf = 0.55 (n-hexane/EtOAc 8:2); mp 113–114 °C.
IR (KBr): 3438, 2923, 1659, 1495, 1340, 1158, 1095 cm–1
.
1H NMR (400 MHz, CDCl3):  = 7.48 (d, J = 8.4 Hz, 3 H), 7.25–7.27 (m, 5
H), 7.18 (s, 1 H),7.14 (d, J = 8.0 Hz, 2 H), 6.00 (s, 1 H), 5.95 (s, 1 H), 5.30
(s, 1 H), 4.78 (s, 2 H), 2.35 (s, 3 H), 2.14 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 146.0, 144.1, 142.4, 140.4, 133.7,
129.7, 128.5, 128.1, 127.9, 127.5, 125.6, 123.6, 118.0, 106.9, 68.9, 52.1,
21.4, 15.5.
MS (EI, 70 eV): m/z (%) = 395 [M+, 100], 318 (60), 240 (45), 155 (40),
91 (60), 77 (70).
Anal. Calcd for C22H21NO4S: C, 66.82; H, 5.35; N, 3.54. Found: C, 66.87;
H, 5.36; N, 3.59.
5-Methyl-1-phenyl-2-(phenylsulfonyl)isoindoline-4,7-diol (4f)
The reaction was carried out according to GP 6 with 3f (0.09 g, 0.25
mmol, 1.0 equiv), and sodium dithionite (1.03 g, 5.0 mmol, 2.0 equiv).
Compound 4f was obtained as a light brown solid after column chro-
matography (eluent: n-hexane/EtOAc (8:2); yield: 0.06 g (75%, 0.18
mmol); Rf = 0.52 (n-hexane/EtOAc 8:2); mp 108–109 °C.
IR (KBr): 3428, 2924, 1658, 1449, 1341, 1161, 1096 cm–1
.
1H NMR (500 MHz, CDCl3):  = 7.56 (t, J = 7.0 Hz, 2 H), 7.45 (t, J = 8.0
Hz, 2 H), 7.33 (t, J = 7.5 Hz, 3 H), 7.23 (s, 5 H), 6.42 (s, 1 H), 5.98 (s, 1
H), 4.83 (d, J = 13.5 Hz, 1 H), 4.76 (d, J = 11.0 Hz, 1 H), 3.62 (s, 1 H),
2.14 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 144.1, 142.4, 140.1, 138.5, 132.3,
129.5, 128.8, 128.6, 127.9, 127.0, 125.6, 123.5, 118.0, 108.3, 67.8, 52.1,
15.4.
MS (EI, 70 eV): m/z (%) = 381 [M+, 100], 304 (85), 240 (60), 141 (45),
77 (90).
Anal. Calcd for C21H19NO4S: C, 66.12; H, 5.02; N, 3.67. Found: C, 66.07;
H, 5.00; N, 3.61.
Funding Information
University of Kashan (Grant Number 573600/3).
U
n
iversity
o
f
K
ashan(5
7
3
6
0
0/3)
(17) Qiu, D.; Zheng, Z.; Mo, F.; Xiao, Q.; Tian, Y.; Zhang, Y.; Wang, J.
Org. Lett. 2011, 13, 4988.
Supporting Information
(18) Morey, J.; Saá, J. M. Tetrahedron 1993, 49, 105.
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