A concise approach for the synthesis of 3-iodoindoles and 3-iodobenzo[b]furans via Ph3P-catalyzed iodocyclization

Article abstract of DOI:10.1016/j.tet.2015.09.005

A variety of 3-iodoindole and 3-iodobenzo[b]furan derivatives were conveniently prepared from the corresponding 2-alkynylanilines and 2-alkynylphenols through Ph₃P-catalyzed iodocyclization in the presence of N-iodosuccinimide (NIS). This proto

Full text of DOI:10.1016/j.tet.2015.09.005

Tetrahedron 71 (2015) 8271e8277
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journal homepage: www.elsevier.com/locate/tet
A concise approach for the synthesis of 3-iodoindoles and
3-iodobenzo[b]furans via Ph3P-catalyzed iodocyclization
*
Yin-Long Li, Jian Li, Sheng-Nan Yu, Ji-Bo Wang, Yan-Min Yu, Jun Deng
Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin
300072, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 June 2015
Received in revised form 1 September 2015
Accepted 3 September 2015
Available online 5 September 2015
A variety of 3-iodoindole and 3-iodobenzo[b]furan derivatives were conveniently prepared from the
corresponding 2-alkynylanilines and 2-alkynylphenols through Ph3P-catalyzed iodocyclization in the
presence of N-iodosuccinimide (NIS). This protocol provides a rapid access to 3-iodoindoles and 3-
iodobenzo[b]furans in good to excellent yields under mild conditions.
Ó 2015 Elsevier Ltd. All rights reserved.
Keywords:
3-Iodoindoles
3-Iodobenzo[b]furans
Triphenylphosphine
Iodocyclization
N-iodosuccinimide
1. Introduction
Indoles and benzo[b]furans are important structural motifs of
many naturally occurring products and pharmaceutical molecules.1
Therefore, numerous efficient synthetic approaches toward the
indoles and benzo[b]furans have been developed.2 Among these
synthetic strategies, transition-metal-catalyzed aromatic CeN for-
mation ranks as a powerful and reliable access to indole scaffolds.3
Recently, remarkable progress has also been made on the synthesis
of benzo[b]furans via cyclization of 2-alkynylphenol derivatives.4
Moreover, due to the potential for further functionalization at the
CeI bond by transition-metal-catalyzed cross coupling reactions,
the development of new strategies to afford 3-iodoindoles and 3-
iodobenzo[b]furans could be valuable. For example, Barluenga
and co-workers have previously reported IPy2BF4 promoted intra-
molecular addition of 2-alkynylanilines to construct 3-iodoindole
cores with moderate yields at low temperature (ꢀ60 ꢁC) (Scheme
1, method A).5a Knight also established a simple strategy for the
synthesis of 3-iodoindoles using 3.0 equiv I2 and K2CO3 (Scheme 1,
method B).5e Besides other strategies, iodine-mediated electro-
philic cyclization of N,N-dialkyl-2-(1-alkynyl)anilines for the syn-
thesis of 3-iodoindoles was accomplished by Larock (Scheme 1,
method C).5b In other papers, Larock and Arcadi have demonstrated
Scheme 1. Synthesis and application of 3-iodoindoles and 3-iodobenzo[b]furans.
* Corresponding author. Tel.: þ86 02227402904; fax: þ86 0222740403; e-mail
address: jdeng@tju.edu.cn (J. Deng).
http://dx.doi.org/10.1016/j.tet.2015.09.005
0040-4020/Ó 2015 Elsevier Ltd. All rights reserved.

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Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
Table 1
the preparation of 3-iodobenzo[b]furans by a related process in-
volving iodocyclization (Scheme 1, method D, E).5e,f In 2008, the
versatile synthesis of benzo[b]furans by iodocyclization of ethox-
yethyl ether-substituted alkynes have been achieved by Wada and
co-workers by using 2.0 equiv [I(coll)2PF6] (Scheme 1, method F).5h
Under the Pyne conditions, the copper mediated cycliza-
tionehalogenation of o-alkynylphenols could afford 3-
iodobenzofurans at higher reaction temperature (135e140 ꢁC)
(Scheme 1, method G).5l Furthermore, the functionalization of 3-
iodoindoles and 3-iodobenzofurans can be accomplished by
palladium-catalyzed coupling reactions at the CeI bond, such as the
Sonogashira and Suzuki cross coupling processes and the Heck
reactions (Scheme 1, Eqs. 1, 2 and 3).5j,k Larock also reported the
synthesis of indole and benzofuran rings by the palladium-
Optimization of reaction conditionsa
Entry
Cat.
Solvent
Time (h)
Yield (%)b
1
d
CH2Cl2
48
7
7
7
7
63
93
80
95
21
96
98
35
51
43
15
25
29
Trace
27
ND
ND
65
2
Ph3PS
Ph3PS
Ph3PSe
Ph3PO
Ph3P
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
3c
4
5
6
7
8
CH2Cl2
4
Ph3P
Ph3P
Dichloroethane
THF
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
catalyzed
cyclocarbonylation
of
3-iodoindoles
and
3-
iodobenzofurans (Scheme 1, Eq. 4).6 Another further elaboration
of 3-iodobenzofurans was the cyclocarbonylation with 2-
iodoaniline or methanol to afford the oxazine ring or benzo[b]fu-
ran-3-carboxylate (Scheme 1, Eq. 5).5f Owing to the considerable
potential of 3-iodoindoles and 3-iodobenzo[b]furans, the rapid and
practical approach to these heterocycles is still highly demanded.
Triphenylphosphine and its derivatives have been widely used
in organic chemistry,7 including several classic ‘name’ reactions,
such as the Wittig reaction,8 Staudinger reaction,9 and Mitsunobu
reaction.10 In particular, phosphines also represent efficient cata-
lysts for Michael,11 BayliseHillman reactions,12 among others.
Given our recent success in the synthesis of indoles via NIS medi-
ated cascade CeN bond formation/aromatization,13 herein, we re-
port a simple and efficient protocol for the synthesis of 3-
iodoindole and 3-iodobenzo[b]furan derivatives through Ph3P-
catalyzed iodocyclization of the corresponding 2-alkynylanilines
and 2-alkynylphenols.
9
Ph3P
Ph3P
Ph3P
Ph3P
DMAP
DABCO
DIPEA
Ph3P
Ph3P
Ph3P
Toluene
CH3CN
1,4-Dioxane
EtOAc
Dichloroethane
Dichloroethane
Dichloroethane
Dichloroethane
Dichloroethane
Dichloroethane
10
11
12
13
14
15
16d
17e
18f
a
Reaction conditions:1a (0.10 mmol), NIS (2.0 equiv), catalyst (0.1 equiv), solvent
(1.0 mL), rt under air.
b
Isolated yield.
1.2 equiv of NIS was used.
2.0 equiv of I2 was used instead of NIS.
2.0 equiv of NCS was used instead of NIS.
c
d
e
f
2.0 equiv of NBS was used instead of NIS. ND¼Not detected. DMAP¼4-
dimethylaminopyridine;
Diisopropylethylamine.
DABCO¼1,4-Diazobicyclo[2.2.2]octane;
DIPEA¼N,N-
2. Results and discussion
entries 16 and 17). Additionally, the use of NBS could produce the 3-
bromoindole in 65% yield (Table 1, entry 18).
Initially, N-Ts-2-alkynylaniline 1a was chosen as the model
substrate to test the feasibility of the proposed transformation. We
were delighted to find that the desired 3-iodoindole 2a was formed
in 63% yield after 48 h without any additives (Table 1, entry 1).
When triphenylphosphine sulfide was used as catalyst, which could
catalyze the iodocyclization process, the reaction time was reduced
to 7 h and the yield of 2a increased to 93% (Table 1, entry 2). It is
note that using 1.2 equiv of NIS could diminish the yield of 2a to 80%
(Table 1, entry 3). We rationalized that the addition of Lewis base
could promote the transformation, thus various triphenylphos-
phine derivatives were surveyed. Triphenylphosphine selenide was
found to be active in catalyzing the iodocyclization reaction, and
the product 2a could be obtained in 95% yield, but triphenylphos-
phine oxide proved to be ineffective, and the yield significantly
decreased to 21% (Table 1, entry 4 and 5). Remarkably, when tri-
phenylphosphine was selected as catalyst, the reaction proceeded
smoothly to give the product in 96% yield (Table 1, entry 6), and the
reaction time was shortened to 4 h. In order to further optimize the
reaction conditions, various solvents were also evaluated. As shown
in Table 1, the reaction showed dramatic solvent effects. Gratify-
ingly, the use of dichloroethane as solvent gave the best result and
furnished 2a in 98% yield within 1.5 h (Table 1, entry 7). Further
solvent screening showed that THF, toluene, and CH3CN were not
effective for this transformation, 1,4-dioxane as well as EtOAc led to
lower yields, only provided product 2a in 15% and 25% yields, re-
spectively (Table 1, entries 8e12). In addition, other Lewis base also
were examined, DMAP and DIPEA could generate 3-iodoindole 2a
in 29% and 27% yields (Table 1, entries 13 and 15). When DABCO was
employed as catalyst, only afforded a trace amount of 2a (Table 1,
entry 14). Compared with NIS, iodine and NCS were sluggish to this
reaction, no desired products were detected after 1.5 h (Table 1,
Next, we investigated the effects of different N-protecting
groups on 2-phenylanilines (Table 2). The results revealed that all
sulfonamides could furnish the corresponding products in good to
excellent yields under the standard conditions, while the N-Ms-
protected substrate (1f) need longer reaction time (Table 2, entries
1e6). Meanwhile, under the same conditions, the substrate with N-
acetyl (1g) also afforded the desired product in 45% yield after 12 h
(Table 2, entry 7). However, the primary amine (1h) group in the
substrate was not tolerated under the optimal reaction conditions,
no desired product was observed after 5 h.
Table 2
Effects of protecting groupsa
Entry
R
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
Ts (1a)
1.5
1.5
1.5
1.5
1.5
12
98 (2a)
78 (2b)
90 (2c)
80 (2d)
70 (2e)
85 (2f)
45 (2g)
ND
C6H5SO2 (1b)
p-BrC6H4SO2 (1c)
p-ClC6H4SO2 (1d)
p-NO2C6H4SO2 (1e)
Ms (1f)
Ac (1g)
H (1h)
12
5
a
Reaction conditions: Substrate 1 (0.1 mmol), NIS (2.0 equiv), Ph3P (0.1 equiv),
ClCH2CH2Cl (1.0 mL), rt under air.
b
Isolated yield. ND¼Not detected.

Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
8273
With the optimized reaction conditions in hand, a series of 2-
alkynylanilines were investigated. The substrates with electron-
donating or -withdrawing group on the phenyl ring all could af-
ford the desired products in good to excellent yields (Table 3, en-
tries 1e8). Noteworthy, when the phenyl ring was appended with
a strong electron-donating group at the ortho-position and para-
position, the reactions are extremely efficient and high-yielding
(Table 3, entries 4 and 5). Comparably, the reaction of the sub-
strate with a para-chloro or fluoro group on the phenyl ring takes
place in relatively slower rate but in good yield (Table 3, entries 6
and 7). A closer inspection revealed that the most strong electron-
withdrawing group (e.g., ꢀCF3) appeared to have retarded the re-
action to some extent, resulted in longer reaction time (24 h) and
moderate yield (Table 3, entry 8). The substrates with a tert-butyl or
cyclopropyl substituents were also successful, and the indoles 2p
and 2q were uneventfully produced in 62% and 96% yields, re-
spectively. However, when the R1 were H or TMS groups, no desired
products were isolated under the optimized conditions (not
shown). Subsequently, we tested the various anilines. The result
indicated that this method could be well applied to various
substituted anilines. When the 2-alkynylanilines (1re1u) were
subjected to the reaction conditions, the corresponding 3-
successfully applied to the synthesis of 3-iodobenzo[b]furans. As
summarized in Table 4, the corresponding 3-iodobenzo[b]furans
were generated in excellent isolated yields (up to 97%). The dif-
ferent substituents on the phenyl ring seemed to have posed little
influence on the reactivities, all the substrates could be converted
with high yields to desired products in a very short time (Table 4,
entries 1e5). The substrates with alkyl substituents were well-
tolerated. For example, the 2-alkynylphenols with tert-butyl and
cyclopropyl moieties could produce the 3-iodobenzo[b]furans in
high efficiency (Table 4, entries 6e7). On the other hand, the re-
action of substituted phenol also proceeded smoothly to give
product 4h in 93% yield within 5 min.
Table 4
Synthesis of 3-iodobenzo[b]furan derivativesa
Entry
R1
R2
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
Ph (3a)
H
H
H
H
H
H
H
Br
5
5
5
5
5
10
30
5
96 (4a)
90 (4b)
97 (4c)
96 (4d)
92 (4e)
91 (4f)
89 (4g)
93 (4h)
4-MeC6H4 (3b)
4-MeOC6H4 (3c)
4-ClC6H4 (3d)
4-FC6H4 (3e)
t-Bu (3f)
Table 3
Synthesis of 3-iodoindole derivativesa
Cyclopropyl (3g)
Ph (3h)
a
Reaction conditions: Substrate 3 (0.1 mmol), NIS (2.0 equiv), Ph3P (0.1 equiv),
ClCH2CH2Cl (1.0 mL), rt under air.
b
Isolated yield.
Entry
R1
R2
Time (h)
Yield (%)b
2.1. Mechanism
1
2
3
4
5
6
7
8
Ph (1a)
H
H
H
H
H
H
H
H
1.5
1.5
6
0.5
0.5
5
18
24
48
1
2
2
2
4
48
12
12
98 (2a)
97 (2i)
82 (2j)
99 (2k)
96 (2l)
92 (2m)
87 (2n)
65 (2o)
62 (2p)
96 (2q)
88 (2r)
92 (2s)
94 (2t)
85 (2u)
60 (2v)
92 (2w)
76 (2x)
4-MeC6H4 (1i)
3-MeC6H4 (1j)
4-MeOC6H4 (1k)
2-MeOC6H4 (1l)
4-CleC6H4 (1m)
4-FeC6H4 (1n)
4-CF3eC6H4 (1o)
t-Bu (1p)
Cyclopropyl (1q)
Ph (1r)
Ph (1s)
Ph (1t)
Ph (1u)
On the basis of all the results described above, a plausible
mechanism for the reaction is described in Scheme 2.14 First, the
iodine atom on NIS is likely activated by the Lewis basic triphe-
nylphosphine to form intermediate A. The electrophilic I might
then be delivered to alkyne 1 to form the intermediate B, which is
subsequently attacked by the amino group to initiate the intra-
molecular amination to furnish the indole product.
9
H
H
10
11
12
13
14
15
16
17
4-Me
4-MeO
4-Cl
4-Br
4-COOEt
4-COOEt
5-Me
Ph (1v)
4-MeOC6H4 (1w)
Ph (1x)
a
Reaction conditions: Substrate 1 (0.1 mmol), NIS (2.0 equiv), Ph3P (0.1 equiv),
ClCH2CH2Cl (1.0 mL), rt under air.
b
Isolated yield.
iodoindoles were obtained in 85e94% yields (Table 3, entries
11e14). The reaction of substrate carrying a ethyl ester group also
have enough reactivity for the indole formation, which furnished
the desired product in a 60% yield but required longer time (48 h),
maybe attributed to the electron withdrawing effect of the ethyl
ester group (Table 3, entry 15). Notably, as for the substrate with
two substituents (1w), the presence of electron-donating group
(ꢀMeO) on the phenyl ring could improve the yield to 92%,
meanwhile reduced the reaction time to 12 h (Table 3, entry 16).
This method is also applicable to the direct synthesis of 6-
substituted indoles. As a representative example, when the sub-
strate 1x was subjected to the reaction conditions, the 6-methyl-2-
phenylindole 2x was observed in 76% yield (Table 3, entry 17).
To further examine the substrates scope of the methodology,
several diversely substituted 2-alkynylphenols were synthesized to
be evaluated. We were delighted to find that this protocol was
Scheme 2. Proposed mechanism.
3. Conclusion
In summary, a practical protocol has been successfully established
for the synthesis of 3-iodoindole and 3-iodobenzo[b]furan de-
rivatives from the corresponding 2-alkynylanilines and 2-
alkynylphenols. Using triphenylphosphine as a catalyst, the iodo-
cyclization process is achieved high efficiently with a broad substrate
scope. Considering the importance of indoles and benzo[b]furans as
core structures in pharmacologically active substances, this method

8274
Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
should be attractive for both synthetic and medicinal chemistry.
Further investigation in this direction is ongoing in our laboratory.
mp: 135e137 ꢁC; Rf¼0.45 (10% EtOAc in petroleum ether); 1H NMR
(400 MHz, CDCl3)
d
7.27 (d, J¼8.8 Hz, 2H), 7.33e7.52 (m, 10H), 8.28
(d, J¼8.4 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d 76.5, 116.0, 122.5,
4. Experimental section
4.1. General information
125.0, 126.4, 127.7, 128.3, 129.2, 129.5, 131.3, 131.7, 132.4, 136.2,
136.9,140.6,140.9; IR (KBr) cmꢀ1 3049w,1581m,1445s,1378s, 772s,
565s; mass spectrum (ESI): m/e (% relative intensity) 515.9 (100)
(MþNa)þ; HRMS (ESI): m/z calcd for C20H13ClINO2S (MþNa)þ
515.9298, found 515.9299.
All reactions were performed in standard glassware. Solvents
were distilled prior to use. All commercially available reagents were
used as purchased without further purification. 1H and 13C NMR
4.2.5. 3-Iodo-N-Ns-2-phenylindole (2e). Reaction time: 1.5 h. Yield:
35.2 mg, 70%, light yellow solid, mp: 175e177 ꢁC; Rf¼0.30 (10%
spectra were obtained on 600 MHz spectrometer (150 MHz for 13
C
13
NMR) or 400 MHz spectrometer (100 MHz for C NMR) at 25 ꢁC,
using CDCl3 with TMS or residual solvent as standard unless oth-
erwise noted. Chemical-shift values were given in ppm and refer-
enced to the internal standard TMS (tetramethylsilane). The peak
patterns are indicated as follows: s, singlet; d, doublet; t, triplet; q,
quadruplet; m, multiplet; dd, doublet of doublets, and br s, broad
singlet. The coupling constants (J) are reported in hertz (Hz). In-
frared spectra were measured on an FT/IR instrument. Melting
points were determined with a micromelting point apparatus
without corrections. Low-resolution mass spectra were obtained
using LS/MSD. High-resolution mass spectrometry (HRMS) was
obtained on a Q-TOF microspectrometer. Flash column chroma-
tography was performed over silica gel 200e300 mesh.
EtOAc in petroleum ether); 1H NMR (400 MHz, CDCl3)
d 7.38 (d,
J¼7.2 Hz, 2H), 7.40e7.52 (m, 6H), 7.59 (d, J¼8.8 Hz, 2H), 8.14 (d,
J¼8.8 Hz, 2H), 8.28 (d, J¼8.2 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d
77.4, 116.0, 122.7, 124.1, 125.5, 126.8, 127.8, 128.2, 129.8, 130.9,
131.7, 132.6, 136.8, 140.7, 142.8, 150.6; IR (KBr) cmꢀ1 3117m, 1608m,
1530s, 1446s, 1383s, 1355s, 564s; mass spectrum (ESI): m/e (% rel-
ative intensity) 526.3 (100) (MþNa)þ; HRMS (ESI): m/z calcd for
C
20H13IN2O4S (MþNa)þ 526.9538, found 526.9569.
4.2.6. 3-Iodo-N-Ms-2-phenylindole (2f). Reaction time: 12 h. Yield:
33.7 mg, 85%, light yellow solid, mp: 128e130 ꢁC; Rf¼0.27 (10%
EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.85 (s,
3H),7.43e7.48 (m, 7H), 7.53 (d, J¼6.6 Hz, 1H), 8.09 (d, J¼7.8 Hz, 1H);
13C NMR (150 MHz, CDCl3)
d 40.8, 75.5, 115.3, 122.5, 125.0, 126.4,
4.2. General procedure for the synthesis of 3-iodoindole, 3-
iodobenzo[b]furan derivatives and characterization data
128.0, 129.6, 131.3, 131.4, 132.1, 136.7, 140.9; IR (KBr) cmꢀ1 3006w,
1446s, 1360s, 1174s, 514s; mass spectrum (ESI): m/e (% relative in-
tensity) 420.1 (100) (MþNa)þ; HRMS (ESI): m/z calcd for
To a solution of substrate 1 or 3 (0.10 mmol) in dichloroethane
(1.0 mL) were added Ph3P (2.62 mg, 0.01 mmol) and NIS (45.0 mg,
0.20 mmol) under air. The resulting mixture was stirred at rt for the
reported time, then the mixture was concentrated under reduced
pressure. The residue was purified by silica gel flash column chro-
matography to give the corresponding product.
C
15H12INO2S (MþNa)þ 419.9531, found 419.9533.
4.2.7. 3-Iodo-N-Ac-2-phenylindole (2g). Reaction time: 12 h. Yield:
16.2 mg, 45%, light yellow solid, Rf¼0.16 (5% EtOAc in petroleum
ether); 1H NMR (600 MHz, CDCl3)
d
2.35 (s, 3H), 6.49 (d, J¼7.8 Hz,
1H), 6.77 (d, J¼7.8 Hz, 1H), 7.15 (d, J¼7.8 Hz, 1H), 7.21 (d, J¼7.2 Hz,
1H), 7.31e7.38 (m, 5H); 13C NMR (150 MHz, CDCl3)
d
21.1, 74.7,
4.2.1. 3-Iodo-2-phenyl-1-(4-toluenesulfonyl)indole (2a).15 Reaction
time: 1.5 h. Yield: 46.4 mg, 98%, light yellow solid, mp: 113e115 ꢁC;
Rf¼0.32 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
119.6, 125.3, 126.2, 126.6, 128.6, 129.3, 129.8, 130.6, 139.9, 141.8,
145.4, 158.4; IR (KBr) cmꢀ1 3050w, 1664s, 1455s, 635s; mass
spectrum (ESI): m/e (% relative intensity) 362.7 (100) (MþH)þ;
HRMS (ESI): m/z calcd for C16H12INO (MþNa)þ 383.9861, found
383.9856.
d
2.31 (s, 3H), 7.08 (d, J¼7.8 Hz, 2H), 7.30e7.48 (m, 10H), 8.31 (d,
J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 20.5, 74.8, 114.9, 121.1,
123.6, 125.0, 125.8, 126.5, 128.3, 128.4, 130.5, 130.7, 131.2, 134.0,
135.9, 140.0, 144.0.
4.2.8. 3-Iodo-N-Ts-2-p-tolylindole (2i). Reaction time: 1.5 h. Yield:
47.2 mg, 97%, light yellow solid, mp: 125e127 ꢁC; Rf¼0.46 (10%
4.2.2. 3-Iodo-N-(benzenesulfonyl)-2-phenylindole
(2b). Reaction
EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.29 (s, 3H),
time: 1.5 h. Yield: 35.8 mg, 78%, light yellow solid, mp: 102e104 ꢁC;
Rf¼0.69 (20% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
2.46 (s, 3H), 7.07 (d, J¼7.8 Hz, 2H), 7.25e7.42 (m, 9H), 8.29 (d,
J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 21.6, 21.7, 75.8, 116.1,
d
7.31 (d, J¼7.2 Hz, 2H), 7.36 (d, J¼6.6 Hz, 2H), 7.38e7.50 (m, 9H), 8.33
122.1, 124.7, 126.0, 126.9, 127.0, 128.3, 128.6, 129.5, 131.6, 132.4,
135.0, 137.0, 139.3, 141.3, 145.0; IR (KBr) cmꢀ1 2917w, 1596s, 1498s,
1446s, 571s; mass spectrum (ESI): m/e (% relative intensity) 510.0
(100) (MþNa)þ; HRMS (ESI): m/z calcd for C22H18INO2S (MþNa)þ
510.0001, found 509.9998.
(d, J¼8.4 Hz,1H); 13C NMR (150 MHz, CDCl3)
d 76.0,116.0,122.3,124.8,
126.2, 126.9, 127.6, 128.9, 129.4, 131.4, 131.8, 132.2, 133.9, 137.0, 138.0,
141.0; IR (KBr) cmꢀ1 3065w, 2376w, 1721m, 1443s, 559s; mass spec-
trum (ESI): m/e (% relative intensity) 481.9 (100) (MþNa)þ; HRMS
(ESI): m/z calcd for C20H14INO2S (MþH)þ 459.9868, found 459.9875.
4.2.9. 3-Iodo-N-Ts-2-m-tolylindole (2j). Reaction time: 6 h. Yield:
39.9 mg, 82%, light yellow solid, Rf¼0.46 (10% EtOAc in petroleum
4.2.3. 3-Iodo-N-(4-bromophenylsulfonyl)-2-phenylindole
(2c). Reaction time: 1.5 h. Yield: 48.2 mg, 90%, white solid, mp:
165e167 ꢁC; Rf¼0.70 (20% EtOAc in petroleum ether); 1H NMR
ether); 1H NMR (600 MHz, CDCl3)
d 2.24 (s, 3H), 2.32 (s, 3H), 7.01 (d,
J¼9.0 Hz, 3H), 7.05 (d, J¼7.2 Hz, 1H), 7.20e7.28 (m, 5H), 7.32e7.36
(600 MHz, CDCl3)
d
7.25 (d, J¼7.2 Hz, 2H), 7.35e7.49 (m,10H), 8.28 (d,
(m, 2H), 8.23 (d, J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 21.5,
J¼7.8 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d
76.6, 116.0, 122.5, 125.0,
21.6, 75.6, 116.0, 122.2, 124.6, 126.0, 127.0, 127.4, 128.8, 129.4, 130.1,
131.4, 132.2, 132.4, 135.2, 137.00, 137.03, 141.3, 145.0; IR (KBr) cmꢀ1
2964s, 1413s, 1261s, 587s; mass spectrum (ESI): m/e (% relative
intensity) 510.2 (100) (MþNa)þ; HRMS (ESI): m/z calcd for
126.4, 127.7, 128.4, 129.3, 129.5, 131.2, 131.8, 132.2, 132.4, 136.7, 136.9,
140.9; IR (KBr) cmꢀ1 3049w, 1573s, 1444m, 1378s, 562s; mass spec-
trum (ESI): m/e (% relative intensity) 559.2 (100) (MþNa)þ; HRMS
(ESI): m/z calcd for C20H13BrINO2S (MþNa)þ 559.8793, found
559.8821.
C
22H18INO2S (MþNa)þ 510.0001, found 509.9989.
4.2.10. 3-Iodo-N-Ts-2-(4-methoxyphenyl)indole (2k). Reaction time:
0.5 h. Yield: 49.8 mg, 99%, light yellow solid, mp: 143e145 ꢁC;
Rf¼0.31 (10% EtOAc in petroleum ether); 1H NMR (400 MHz, CDCl3)
4.2.4. 3-Iodo-N-(4-chlorophenylsulfonyl)-2-phenylindole
(2d). Reaction time: 1.5 h. Yield: 39.4 mg, 80%, light yellow solid,

Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
8275
d
2.30 (s, 3H), 3.89 (s, 3H), 6.98 (d, J¼8.8 Hz, 2H), 7.08 (d,
476.9 (100) (MþNa)þ; HRMS (ESI): m/z calcd for C19H20INO2S
(MþNa)þ 476.0157, found 476.0149.
J¼8.0 Hz, 2H), 7.27e7.43 (m, 7H), 8.30 (d, J¼8.0 Hz, 1H); 13C NMR
(100 MHz, CDCl3)
d 21.6, 55.3, 75.7, 113.0, 116.1, 122.1, 123.6,
124.6, 125.9, 126.9, 129.5, 132.3, 133.2, 135.1, 137.0, 141.1, 145.0, 160.3;
IR (KBr) cmꢀ1 3034w, 2916w, 1610s, 1501s, 1438s, 542s; mass
spectrum (ESI): m/e (% relative intensity) 525.6 (100) (MþNa)þ;
HRMS (ESI): m/z calcd for C22H18INO3S (MþNa)þ 525.9950, found
525.9972.
4.2.16. 3-Iodo-N-Ts-2-cyclopropylindole (2q). Reaction time: 1 h.
Yield: 41.9 mg, 96%, light yellow solid, mp: 89e91 ꢁC; Rf¼0.48 (10%
EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 0.90e0.92
(m, 2H), 1.10e1.12 (m, 2H), 1.97e2.00 (m, 1H), 2.33 (s, 3H), 7.17 (d,
J¼7.8 Hz, 2H), 7.29 (d, J¼7.8 Hz, 1H), 7.34 (d, J¼7.2 Hz, 2H), 7.65 (d,
J¼7.8 Hz, 2H), 8.16 (d, J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
4.2.11. 3-Iodo-N-Ts-2-(2-methoxyphenyl)indole (2l). Reaction time:
0.5 h. Yield: 48.3 mg, 96%, white solid, mp: 135e137 ꢁC; Rf¼0.33
d 9.9, 10.4, 21.6, 73.5, 115.0, 121.8, 124.1, 125.7, 126.5, 129.8, 131.9,
136.3, 136.9, 140.5, 144.9; IR (KBr) cmꢀ1 3013w, 1596s, 1447s, 1367s,
542s; mass spectrum (ESI): m/e (% relative intensity) 459.3 (100)
(MþNa)þ; HRMS (ESI): m/z calcd for C18H16INO2S (MþNa)þ
459.9844, found 459.9826.
(10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.33 (s,
3H), 3.71 (s, 3H), 6.97 (d, J¼8.4 Hz, 1H), 7.04 (t, J¼7.2 Hz, 1H), 7.11 (d,
J¼7.8 Hz, 2H), 7.15 (d, J¼7.2 Hz, 1H), 7.34 (t, J¼7.2 Hz, 1H), 7.38e7.43
(m, 4H), 7.50 (d, J¼7.8 Hz, 1H), 8.23 (d, J¼8.4 Hz, 1H); 13C NMR
(150 MHz, CDCl3)
d
21.6, 55.4, 75.4, 110.8, 115.3, 119.7, 120.9, 121.9,
4.2.17. 3-Iodo-N-Ts-5-methyl-2-phenylindole (2r). Reaction time:
2 h. Yield: 42.9 mg, 88%, light yellow solid, mp: 95e97 ꢁC; Rf¼0.47
124.1, 125.6, 127.1, 129.4, 131.3, 132.0, 133.1, 135.7, 136.6, 138.3, 144.7,
158.4; IR (KBr) cmꢀ1 3478m, 1488m, 1444s, 1374s, 544s; mass
spectrum (ESI): m/e (% relative intensity) 504.0 (100) (MþH)þ;
HRMS (ESI): m/z calcd for C22H18INO3S (MþNa)þ 525.9950, found
525.9949.
(10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.30 (s,
3H), 2.47 (s, 3H), 7.07 (d, J¼7.2 Hz, 2H), 7.18 (s, 1H), 7.22e7.24 (m,
2H), 7.30 (d, J¼7.8 Hz, 2H), 7.37 (d, J¼6.6 Hz, 2H), 7.43e7.49 (m, 3H),
8.17 (d, J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 21.3, 21.6, 75.9,
115.8, 122.0, 126.9, 127.5, 129.3, 129.5, 131.6, 131.7, 132.5, 134.6,
135.0, 135.2, 141.1, 144.9; IR (KBr) cmꢀ1 2916w, 1596m, 1467s,1368s,
546s; mass spectrum (ESI): m/e (% relative intensity) 488.8 (100)
(MþH)þ; HRMS (ESI): m/z calcd for C22H18INO2S (MþH)þ 488.0181,
found 488.0214.
4.2.12. 3-Iodo-N-Ts-2-(4-chlorophenyl)indole (2m). Reaction time:
5 h. Yield: 46.5 mg, 92%, light yellow solid, mp: 168e170 ꢁC;
Rf¼0.59 (10% EtOAc in petroleum ether); 1H NMR (600 MHz,
CDCl3)
d
2.23 (s, 3H), 7.01 (d, J¼7.8 Hz, 2H), 7.23 (d, J¼7.8 Hz,
4H), 7.25e7.37 (m, 5H), 8.22 (d, J¼8.4 Hz, 1H); 13C NMR
(150 MHz, CDCl3)
d
21.6, 76.4, 116.1, 122.3, 124.9, 126.4, 126.8,
4.2.18. 3-Iodo-N-Ts-5-methoxy-2-phenylindole (2s). Reaction time:
2 h. Yield: 46.3 mg, 92%, light yellow solid, mp: 70e72 ꢁC; Rf¼0.36
127.9, 129.6, 130.0, 132.2, 133.0, 134.9, 135.5, 137.1, 139.8, 145.3;
IR (KBr) cmꢀ1 3058w, 1908w, 1597s, 1484s, 1381s, 571s; mass
spectrum (ESI): m/e (% relative intensity) 507.6 (100) (MþH)þ;
HRMS (ESI): m/z calcd for C21H15ClINO2S (MþNa)þ 529.9454,
found 529.9430.
(10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.32 (s,
3H), 3.88 (s, 3H), 6.82 (s,1H), 7.03 (d, J¼7.8 Hz,1H), 7.08 (d, J¼7.8 Hz,
2H), 7.29 (d, J¼7.8 Hz, 2H), 7.38 (d, J¼7.2 Hz, 2H), 7.44e7.48 (m, 3H),
8.19 (d, J¼9.0 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 21.6, 55.7, 76.0,
104.3, 115.1, 117.3, 126.9, 127.5, 129.3, 129.4, 131.4, 131.6, 131.7, 133.5,
134.8, 141.9, 144.9, 157.5; IR (KBr) cmꢀ1 2990w, 1609s, 1472s, 1434s,
542s; mass spectrum (ESI): m/e (% relative intensity) 525.8 (100)
(MþNa)þ; HRMS (ESI): m/z calcd for C22H18INO3S (MþNa)þ
525.9950, found 525.9944.
4.2.13. 3-Iodo-N-Ts-2-(4-fluorophenyl)indole (2n). Reaction time:
18 h. Yield: 42.7 mg, 87%, light yellow solid, mp: 183e185 ꢁC; Rf¼0.38
(10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.24 (s,
3H), 7.01 (d, J¼7.8 Hz, 2H), 7.06 (t, J¼8.4 Hz, 2H), 7.21e7.33 (m, 6H),
7.36 (t, J¼7.2 Hz, 1H), 8.22 (d, J¼8.4 Hz, 1H); 13C NMR (150 MHz,
CDCl3)
d
20.6, 75.1,113.7 (d, J¼21.6 Hz),115.0,121.2,123.7,125.2,125.8,
4.2.19. 3-Iodo-N-Ts-5-chloro-2-phenylindole (2t). Reaction time:
2 h. Yield: 47.7 mg, 94%, light yellow solid, mp: 129e131 ꢁC;
Rf¼0.47 (10% EtOAc in petroleum ether); 1H NMR (600 MHz,
126.4 (d, J¼3.2 Hz),128.5,131.0,132.6 (d, J¼8.2 Hz),134.0,135.9,138.9,
144.1, 163.0 (d, J¼248.2 Hz); IR (KBr) cmꢀ1 3066w, 1597s, 1496s,
1375s, 540s; mass spectrum (ESI): m/e (% relative intensity) 490.5
(100) (MþH)þ; HRMS (ESI): m/z calcd for C21H15FINO2S (MþNa)þ
513.9750, found 513.9757.
CDCl3)
d
2.33 (s, 3H), 7.10 (d, J¼7.8 Hz, 2H), 7.27 (d, J¼7.8 Hz,
2H), 7.33 (d, J¼7.2 Hz, 2H), 7.37e7.39 (m, 2H), 7.45 (t, J¼7.2 Hz,
2H), 7.49 (d, J¼7.2 Hz, 1H), 8.24 (d, J¼8.4 Hz, 1H); 13C NMR
(150 MHz, CDCl3)
d 21.7, 74.2, 117.2, 121.9, 126.2, 126.9, 127.6,
4.2.14. 3-Iodo-N-Ts-2-(4-trifluoromethyl)indole (2o). Reaction time:
24 h. Yield: 35.1 mg, 65%, light yellow solid, mp: 153e155 ꢁC;
Rf¼0.57 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
129.6, 129.6, 130.6, 131.0, 131.7, 133.6, 134.8, 135.4, 142.5, 145.4;
IR (KBr) cmꢀ1 3459m, 1597s, 1440s, 1370s, 544s; mass spectrum
(ESI): m/e (% relative intensity) 529.6 (100) (MþNa)þ; HRMS
(ESI): m/z calcd for C21H15ClINO2S (MþH)þ 507.9635, found
507.9650.
d
2.25 (s, 3H), 7.02 (d, J¼7.2 Hz, 2H), 7.23 (d, J¼7.8 Hz, 2H), 7.29e7.40
(m, 3H), 7.44 (d, J¼7.8 Hz, 2H), 7.64 (d, J¼7.8 Hz, 2H), 8.23 (d,
J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 20.6, 115.0, 121.4, 122.1,
123.5 (q, J¼3.5 Hz), 123.9, 125.6, 125.8, 128.6, 129.9, 130.1, 131.0,
131.2, 133.7, 134.2, 136.0, 138.3, 144.3; IR (KBr) cmꢀ1 3479m, 1617m,
1598s, 1381s, 571s; mass spectrum (ESI): m/e (% relative intensity)
563.6 (100) (MþNa)þ; HRMS (ESI): m/z calcd for C22H15F3INO2S
(MþNa)þ 563.9718, found 563.9734.
4.2.20. 3-Iodo-N-Ts-5-bromo-2-phenylindole (2u). Reaction time:
4 h. Yield: 46.8 mg, 85%, light yellow solid, Rf¼0.37 (10% EtOAc in
petroleum ether); 1H NMR (600 MHz, CDCl3)
d 2.33 (s, 3H), 7.10 (d,
J¼7.8 Hz, 2H), 7.28 (d, J¼7.8 Hz, 2H), 7.33 (d, J¼7.2 Hz, 2H), 7.45 (t,
J¼7.2 Hz, 2H), 7.48e7.52 (m, 2H), 7.55 (s, 1H), 8.18 (d, J¼9.0 Hz, 1H);
13C NMR (150 MHz, CDCl3)
d 21.7, 74.1, 117.5, 118.2, 124.9, 126.9,
4.2.15. 3-Iodo-N-Ts-2-tert-butylindole (2p). Reaction time: 48 h.
Yield: 28.1 mg, 62%, light yellow solid, mp: 66e68 ꢁC; Rf¼0.52 (10%
127.6, 128.9, 129.5, 129.6, 131.0, 131.7, 134.0, 134.8, 135.8, 142.4,
145.4; IR (KBr) cmꢀ1 3068w, 1594s, 1438s, 1376s, 544s; mass
spectrum (ESI): m/e (% relative intensity) 574.4 (100) (MþNa)þ;
HRMS (ESI): m/z calcd for C21H15BrINO2S (MþNa)þ 573.8949, found
573.8925.
EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d 1.79 (s, 9H),
2.23 (s, 3H), 6.94 (d, J¼7.8 Hz, 2H), 7.10 (d, J¼7.8 Hz, 1H), 7.15 (t,
J¼7.2 Hz, 1H), 7.19e7.25 (m, 3H), 7.92 (d, J¼8.4 Hz, 1H); 13C NMR
(150 MHz, CDCl3)
d 21.5, 31.9, 36.4, 80.3, 118.3, 121.9, 125.4, 125.7,
126.8, 128.5, 131.7, 136.4, 139.6, 144.2, 151.5; IR (KBr) cmꢀ1 3398m,
4.2.21. 3-Iodo-N-Ts-2-phenyl-5-ethoxycarbonylindole (2v). Reaction
time: 48 h. Yield: 32.7 mg, 60%, light yellow solid, mp: 145e147 ꢁC;
2962s, 1457s, 570s; mass spectrum (ESI): m/e (% relative intensity)

8276
Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
Rf¼0.24 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
128.8, 132.4, 135.2, 151.9, 153.9; IR (KBr) cmꢀ1 3502w, 1482s, 1448s,
723s; mass spectrum (ESI): m/e (% relative intensity) 376.9 (100)
(MþNa)þ; HRMS (ESI): m/z calcd for C14H8ClIO (MþH)þ 354.9387,
found 354.9356.
d
1.44 (t, J¼7.2 Hz, 3H), 2.33 (s, 3H), 4.43 (q, J¼6.6 Hz, 2H), 7.10 (d,
J¼7.8 Hz, 2H), 7.31 (d, J¼7.8 Hz, 2H), 7.34 (d, J¼7.2 Hz, 2H), 7.45 (t,
J¼7.2 Hz, 2H), 7.50 (t, J¼7.2 Hz, 1H), 8.13 (d, J¼8.4 Hz, 2H), 8.36 (d,
J¼8.4 Hz, 1H); 13C NMR (150 MHz, CDCl3)
d 14.4, 21.6, 61.2, 75.5,
115.7, 124.3, 126.9, 127.0, 127.1, 127.6, 129.1, 129.5, 129.6, 131.1, 131.7,
132.1, 134.9, 139.6, 142.3, 145.4, 166.4; IR (KBr) cmꢀ1 2970w, 1709s,
1379s, 1311s, 1090s, 546s; mass spectrum (ESI): m/e (% relative in-
tensity) 568.0 (100) (MþNa)þ; HRMS (ESI): m/z calcd for
4.2.28. 2-(4-Fluorophenyl)-3-iodobenzofuran (4e). Reaction time:
5 min. Yield: 31.1 mg, 92%, light yellow solid, Rf¼0.50 (100% pe-
troleum ether); 1H NMR (600 MHz, CDCl3)
d
7.18 (t, J¼8.4 Hz, 2H),
7.31 (t, J¼7.2 Hz, 1H), 7.36 (t, J¼7.2 Hz, 1H), 7.42 (d, J¼7.8 Hz, 1H),
C
24H20INO4S (MþNa)þ 568.0055, found 568.0039.
7.46 (d, J¼7.8 Hz, 1H), 8.15 (t, J¼5.4 Hz, 2H); 13C NMR (150 MHz,
CDCl3)
d
61.0, 111.2, 115.8 (d, J¼21.6 Hz), 121.9, 123.6, 125.8, 126.3 (d,
4.2.22. 3-Iodo-N-Ts-2-(4-methoxyphenyl)-5-ethoxycarbonylindole
(2w). Reaction time: 12 h. Yield: 52.9 mg, 92%, light yellow solid,
mp: 105e107 ꢁC; Rf¼0.19 (10% EtOAc in petroleum ether); 1H NMR
J¼3.2 Hz), 129.5 (d, J¼8.4 Hz), 132.4, 152.3, 153.9, 163.9 (d,
J¼248.9 Hz); IR (KBr) cmꢀ1 3485w, 1602m, 1497s, 1408m, 742s;
mass spectrum (ESI): m/e (% relative intensity) 338.1 (100)
(MþH)þ; HRMS (ESI): m/z calcd for C14H8FIO (MþNa)þ 360.9502,
found 360.9501.
(600 MHz, CDCl3)
d
1.43 (t, J¼7.2 Hz, 3H), 2.32 (s, 3H), 3.90 (s, 3H),
4.43 (q, J¼6.6 Hz, 2H), 6.98 (d, J¼7.8 Hz, 2H), 7.10 (d, J¼7.8 Hz, 2H),
7.26e7.29 (m, 4H), 8.12 (d, J¼10.2 Hz, 2H), 8.36 (d, J¼8.4 Hz,1H); 13
C
NMR (150 MHz, CDCl3)
d
14.5, 21.7, 55.3, 61.2, 75.4, 113.0, 115.8,
4.2.29. 2-(t-Butyl)-3-iodobenzofuran (4f).5h Reaction time: 10 min.
Yield: 27.3 mg, 91%, light yellow oil, Rf¼0.89 (10% EtOAc in petro-
123.0, 124.1, 126.9, 129.6, 132.2, 133.2, 134.9, 139.7, 142.4, 145.4,
160.5, 166.4; IR (KBr) cmꢀ1 2983w, 1715s, 1612s, 1501s; 1380s,
1097s, 545s; mass spectrum (ESI): m/e (% relative intensity) 598.6
(100) (MþNa)þ; HRMS (ESI): m/z calcd for C25H22INO5S (MþNa)þ
598.0161, found 598.0151.
leum ether); 1H NMR (600 MHz, CDCl3)
d 1.45 (s, 9H), 7.14e7.18 (m,
2H), 7.27e7.29 (m, 2H); 13C NMR (150 MHz, CDCl3)
d 29.5, 34.7, 57.7,
110.8, 121.2, 123.0, 124.6, 132.5, 152.9, 162.4.
4.2.30. 2-Cyclopropyl-3-iodobenzofuran
30 min. Yield: 25.2 mg, 89%, light yellow oil, Rf¼0.91 (10% EtOAc in
petroleum ether); 1H NMR (600 MHz, CDCl3)
1.04e1.06 (m, 2H),
(4g). Reaction
time:
4.2.23. 3-Iodo-N-Ts-6-methyl-2-phenylindole (2x). Reaction time:
12 h. Yield: 37.0 mg, 76%, light yellow solid, mp: 178e180 ꢁC;
Rf¼0.63 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d
1.13e1.14 (m, 2H), 2.16e2.19 (m, 1H), 7.23 (t, J¼8.4 Hz, 2H), 7.30 (t,
d
2.24 (s, 3H), 2.48 (s, 3H), 7.01 (d, J¼7.8 Hz, 2H), 7.11 (d, J¼7.8 Hz,
J¼7.8 Hz, 2H); 13C NMR (150 MHz, CDCl3)
d 7.8, 9.7, 61.1, 110.8, 120.2,
1H), 7.19e7.26 (m, 5H), 7.34e7.40 (m, 3H), 8.04 (s, 1H); 13C NMR
(150 MHz, CDCl3) 20.6, 21.1, 74.7, 115.0, 120.7, 125.0, 125.8, 126.4,
123.2, 124.2, 131.4, 153.3, 158.6; IR (KBr) cmꢀ1 3012m, 1754s, 1696s,
1589s, 744s; mass spectrum (ESI): m/e (% relative intensity) 284.2
(100) (MþH)þ; HRMS (ESI): m/z calcd for C11H9IO (MþNa)þ
306.9596, found 306.9610.
d
128.1, 128.4, 129.1, 130.6, 130.7, 134.1, 135.3, 136.3, 139.3, 143.9. IR
(KBr) cmꢀ1 3052w, 1597w, 1371s, 1189s, 1032s, 801s, 578s; mass
spectrum (ESI): m/e (% relative intensity) 510.0 (100) (MþNa)þ;
HRMS (ESI): m/z calcd for C22H17INO2S (MꢀH)ꢀ 486.0019, found
486.0029.
4.2.31. 5-Bromo-3-iodo-2-phenylbenzofuran (4h). Reaction time:
5 min. Yield: 36.9 mg, 93%, light yellow solid, Rf¼0.53 (100% pe-
troleum ether); 1H NMR (600 MHz, CDCl3)
d
7.34 (d, J¼8.4 Hz, 1H),
4.2.24. 3-Iodo-2-phenylbenzofuran (4a).5d Reaction time: 5 min.
Yield: 30.7 mg, 96%, light yellow oil, Rf¼0.53 (100% petroleum
7.44 (t, J¼7.8 Hz, 2H), 7.48 (t, J¼7.8 Hz, 2H), 7.57 (s, 1H), 8.14 (d,
J¼7.8 Hz, 2H); 13C NMR (150 MHz, CDCl3)
d 59.7, 112.7, 116.7, 124.6,
ether); 1H NMR (600 MHz, CDCl3)
d
7.31 (t, J¼7.2 Hz, 1H), 7.35 (t,
127.6, 128.5, 128.6, 129.5, 129.7, 134.5, 152.7, 154.3; IR (KBr) cmꢀ1
3485m, 1601m, 1487s, 1436s, 766s, 684s; mass spectrum (ESI): m/e
(% relative intensity) 420.5 (100) (MþNa)þ; HRMS (ESI): m/z calcd
for C14H8BrIO (MþH)þ 398.8881, found 398.8856.
J¼7.2 Hz, 1H), 7.40e7.50 (m, 5H), 8.18 (d, J¼15.2 Hz, 2H); 13C NMR
(150 MHz, CDCl3) d 61.2, 111.2, 121.9, 123.6, 125.7, 127.5, 128.6, 129.3,
130.0, 132.5, 153.1, 153.9.
4.2.25. 3-Iodo-2-(p-tolyl)benzofuran (4b). Reaction time: 5 min.
Yield: 30.1 mg, 90%, light yellow solid, Rf¼0.55 (100% petroleum
4.2.32. 3-Bromo-2-phenyl-1-(4-toluenesulfonyl)indole
(2a0).16 Reaction time: 1.5 h. Yield: 27.2 mg, 64%, light yellow solid,
Rf¼0.72 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
ether); 1H NMR (600 MHz, CDCl3)
d 2.41 (s, 3H), 7.28e7.34 (m, 4H),
7.43 (d, J¼7.2 Hz, 1H), 7.46 (d, J¼7.8 Hz, 1H), 8.06 (d, J¼7.8 Hz, 2H);
d
2.30 (s, 3H), 7.07 (d, J¼7.8 Hz, 2H), 7.30 (d, J¼7.8 Hz, 2H), 7.37 (t,
13C NMR (150 MHz, CDCl3)
d
21.5, 60.5, 111.1, 121.7, 123.5, 125.5,
J¼7.8 Hz, 1H), 7.43e7.49 (m, 7H), 8.35 (d, J¼8.4 Hz, 1H); 13C NMR
127.2, 127.5, 129.3, 132.6, 139.4, 153.4, 153.9; IR (KBr) cmꢀ1 3494m,
2915w, 1498m, 492s; mass spectrum (ESI): m/e (% relative in-
tensity) 334.7 (100) (MþH)þ; HRMS (ESI): m/z calcd for C15H11IO
(MþH)þ 334.9933, found 334.9931.
(150 MHz, CDCl3) d 21.6,103.8,116.3,120.0,124.8,126.2,126.9,127.6,
129.3, 129.5, 129.8, 130.1, 131.6, 134.6, 136.6, 137.6, 145.1.
Acknowledgements
4.2.26. 3-Iodo-2-(4-methoxyphenyl)benzofuran
(4c).5d Reaction
We thank Professor Richard P. Hsung [University of Wisconsin at
Madison] for invaluable discussions. The project sponsored by the
Scientific Research Foundation for the Returned Overseas Chinese
Scholars, State Education Ministry, the National Basic Research
Project (No. 2014CB932201) and the National Natural Science
Foundation of China (No. 21172168).
time: 5 min. Yield: 34.0 mg, 97%, light yellow solid, mp: 75e77 ꢁC;
Rf¼0.50 (10% EtOAc in petroleum ether); 1H NMR (600 MHz, CDCl3)
d
3.86 (s, 3H), 7.01 (d, J¼8.4 Hz, 2H), 7.27e7.33 (m, 2H), 7.41 (d,
J¼7.2 Hz, 1H), 7.45 (d, J¼7.2 Hz, 1H), 8.12 (d, J¼8.4 Hz, 2H); 13C NMR
(150 MHz, CDCl3) d 55.4, 59.5, 111.0, 114.0, 121.6, 122.6, 123.4, 125.3,
129.1, 132.6, 153.3, 153.8, 160.4.
Supplementary data
4.2.27. 2-(4-Chlorophenyl)-3-iodobenzofuran (4d). Reaction time:
5 min. Yield: 34.0 mg, 96%, light yellow solid, Rf¼0.48 (100% pe-
Characterization data, general procedure for the synthesis of
substrates, and 1H and 13C NMR spectra for substrates and products.
Supplementary data associated with this article can be found in the
online version, at http://dx.doi.org/10.1016/j.tet.2015.09.005.
troleum ether); 1H NMR (600 MHz, CDCl3)
d
7.32 (t, J¼7.2 Hz, 1H),
7.37 (d, J¼7.2 Hz, 1H), 7.42e7.47 (m, 4H), 8.12 (d, J¼8.4 Hz, 2H); 13
C
NMR (150 MHz, CDCl3) d 61.7, 111.2, 122.0, 123.7, 126.0, 128.5, 128.6,

Y.-L. Li et al. / Tetrahedron 71 (2015) 8271e8277
8277
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