Iodine-catalyzed intramolecular oxidative thiolation of vinylic carbon-hydrogen bonds via tandem iodocyclization and dehydroiodination: Construction of 2-methylene-3-thiophenones

Article abstract of DOI:10.1002/adsc.201300815

A metal-free vinylic carbon-hydrogen bond thiolation has been developed. Under the catalysis of iodine (10 mol%), the cyclization of α-alkenoyl ketene dithioacetals afforded a broad range of polyfunctionalized 2-methylene-3-thiophenones in good selectivity with moderate to excellent yields via tandem iodocyclization and dehydroiodination. The synthetic strategy can also be extended to the cyclization of ortho-methylthiophenyl vinyl ketones leading to 2-methylene-3-benzothiophenones.

Full text of DOI:10.1002/adsc.201300815

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DOI: 10.1002/adsc.201300815
Iodine-Catalyzed Intramolecular Oxidative Thiolation of Vinylic
Carbon-Hydrogen Bonds via Tandem Iodocyclization and
Dehydroiodination: Construction of 2-Methylene-3-thiophenones
Gang Zheng,a Xiaoli Ma,a Bangyu Liu,a Ying Dong,a and Mang Wanga,*
a
Department of Chemistry, Northeast Normal University, Changchun 130024, Peopleꢀs Republic of China
Fax : (+86)+431-8509-9759; phone: (+86)+431-8509-9759; e-mail: wangm452@nenu.edu.cn
Received: September 7, 2013; Revised: November 13, 2013; Published online: March 3, 2014
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300815.
Abstract: A metal-free vinylic carbon-hydrogen
bond thiolation has been developed. Under the cat-
alysis of iodine (10 mol%), the cyclization of a-alk-
or metalating agent followed by quenching with S-
containing electrophiles could directly afford olefinic
[10]
ꢀ
C S cross-coupling products [Scheme 1, Eq. (1)].
enoyl ketene dithioacetals afforded a broad range
Tandem addition of PhSCl to olefins and elimination
of polyfunctionalized 2-methylene-3-thiophenones
in good selectivity with moderate to excellent yields
via tandem iodocyclization and dehydroiodination.
The synthetic strategy can also be extended to the
cyclization of ortho-methylthiophenyl vinyl ketones
leading to 2-methylene-3-benzothiophenones.
of HCl in the presence of t-BuOK also provided ole-
finic C H thiolated products [Scheme 1, Eq. (2)].
[11]
ꢀ
The intramolecular version alternatively involved the
iodocyclization and sequential dehydroiodination of
unsaturated thioamides/thioesters under basic condi-
tions [Scheme 1, Eq. (3)].[12] However, stoichiometric
iodine and basic additives were required for efficient
conversions of the substrates in these processes.[12] It
Keywords: carbon-sulfur bond formation; heterocy-
cles; iodine; selectivity; synthetic methods
ꢀ
is true that a catalytic method for vinylic C H thiola-
tion still challenges this field. Herein, we are pleased
[1]
ꢀ
C S bond formation presents a key step for the syn-
thesis of numerous structurally interesting and biolog-
ically active compounds.[2] The thiol-based transfor-
mations, including thiol-aryl/vinyl halides cross-cou-
pling[1,3] and hydrothiolation of alkynes,[1,4] have
become two main methods for the construction of
2
ꢀ
sp C S bond. Over the past few decades, transition
ꢀ
metal-catalyzed C H functionalization has fascinated
organic chemists.[5] Accordingly, significant progress
2
ꢀ
has been achieved in inter- and intramolecular sp C
ꢀ
S cross-coupling based on the C H bond. In this field,
many transition metals, such as Cu,[6] Pd[7] and Fe,[8]
ꢀ
have proved to be efficient catalysts for aromatic C S
bond oxidative coupling. Recently, a metal-free thio-
lation of aromatic heterocycles with diaryl disulfides
was also developed[9] with the advantages of safety
and no risk of deactivation of the metal catalyst by S-
containing substrates. In contrast, the vinylic C H thi-
olation has been seldom investigated and often lacks
ꢀ
generality although it is anticipated to be a process of
2
ꢀ
synthetic potential for sp C S bond formation.
ꢀ
Among the limited methods for vinylic C H thiola-
2
ꢀ
ꢀ
tion, deprotonation of sp C H bonds by a strong base Scheme 1. Inter- and intramolecular vinylic C H thiolations.
Adv. Synth. Catal. 2014, 356, 743 – 748
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Gang Zheng et al.
2
ꢀ
to disclose a new I2-catalyzed intramolecular sp C H
thiolation of olefins tethered with an alkylthio group
under neutral conditions leading to 2-methylene-3-
thiophenones in good regioselectivity [Scheme 1, Eq.
(4)].
The present work arose from our interest in seeking
new cyclization strategies based on a-alkenoyl ketene
dithioacetals 1 [Scheme 1, Eq. (4), R’=SR][13] for the
construction of various functionalized cyclic com-
pounds.[14] Recently, electrophilic cyclization of heter-
oatom nucleophiles with alkenes/alkynes has become
an extremely active and original field of heterocycle
synthesis.[15] On the basis of the structural nature of
compounds 1, a kind of olefinic substrate bearing
Figure 1. ORTEP diagram of 2a.
a suitably placed sulfur-based nucleophilic group, we phen-3(2H)-one 2a by NMR, MS and further by X-
envisioned an I2-mediated electrophilic cyclization of ray crystallography
AHCTUNGTRENNUNG
1 providing a straightforward access to useful S-het- also observed in a ratio of 8:2 (2a:3a) based on
erocycles. Fortunately and interestingly, the cy- 1H NMR analysis (entry 1). High temperature proved
ACHTUNGTRENNUNGclization was successfully achieved along with some to benefit the process and the reaction was completed
attractive new chemistry: (i) the formation of the in 1.5 h at 1308C (entry 2). Interestingly, the reaction
2
ꢀ
sp C S bond occurs only in the presence of a catalytic afforded a mixture of 2a and 3a in 99% yield even in
amount of iodine (10 mol%); thus, (ii) a new oxida- the presence of a less than a stoichiometric amount of
ꢀ
tive thiolation of olefinic C H bonds is realized; and iodine (entries 3–5). On elevating the temperature to
(iii) the polyfunctionalized 2-methylene-3-thiophe- 1508C, the cyclization could be complete in 8 h with
none products provide additional opportunities for excellent yield and regioselectivity under the catalysis
structural diversification.
of 10 mol% of iodine (entry 6). Further decreasing
Initial investigations showed that the cyclization of the amount of I2 led to longer reaction time and
1a could take place in DMSO in the presence of I2 lower regioselectivity (entry 7). Additionally, other
(1.2 equiv.) at room temperature for 48 h (Table 1, electrophilic catalysts, NIS and NBS, were found to
entry 1). The major product was identified as (Z)- be less efficient than I2 for this cyclization (entries 8
2-benzylidene-5-(ethylthio)-4-(4-methoxyphenyl)thio-
and 9). A complex mixture was obtained with Br2 as
catalyst (entry 10). Finally, the reaction solvent was
found to play an important role. The transformation
of 1a was very slow in DMF (entry 11).
Table 1. Screening reaction conditions.[a]
ꢀ
Very recently, I2-mediated/catalyzed C H function-
alization has been an area of intensive research due
to its mild, low-cost, non-toxic, and unique catalytic
properties.[17] The above reaction showed us a novel
2
ꢀ
and efficient I2-catalyzed oxidative sp C H thiolation
under neutral conditions. Thus, a set of ketene di-
thioacetals 1 was prepared to probe the scope of this
process under the optimized reaction conditions
(Table 1, entry 6). In generally, various ketene di-
thioacetals 1 could be selectively converted into the
cyclic products in moderate to excellent yields
(Table 2). For example, ketene diethyl thioacetals 1a–
o with both electron-rich and electron-deficient aro-
matic R1 and R2 groups effectively afforded a mixture
of 2 and 3 in 60–99% isolated yields, respectively (en-
tries 1–15). The reaction conditions were also compat-
ible with 1p and 1q bearing dimethylthio and diben-
zylthio functional groups (entries 16 and 17). Sub-
strates 1r and 1s with aliphatic R1 or R2 substituents
gave the corresponding cyclic products in good yields
(entries 18 and 19). Additionally, 1t with an electron-
withdrawing benzoyl group at the a-position also
worked well to give the desired mixture of 2t and 3t
Entry Cat.
(equiv.)
Solvent
T
t
Yield[b] Ratio[c]
[oC] [h] 2a+3a 2a:3a
ACHTUNGTRENNUNG
1
2
3
4
I2 (1.2)
I2 (1.2)
I2 (0.5)
I2 (0.2)
I2 (0.1)
DMSO r.t.
DMSO 130 1.5 99%
DMSO 130 99%
DMSO 130 14 99%
DMSO 130 28 98%
DMSO 150
DMSO 150 14 96%
DMSO 150 16 96%
48 17%
80:20
94:6
7
89:11
90:10
85:15
92:8
87:13
71:29
77:23
–
5
6
7
I
G
8
98%
I2 (0.05)
8
NIS (0.1)
9
NBS (0.1) DMSO 150 24 5%
[d]
10
11
Br2 (0.1)
I2 (0.1)
DMSO 150
DMF 150 20 5%
6
–
60:40
[a]
[b]
[c]
[d]
Reaction conditions: 1a (0.2 mmol), solvent (2 mL).
Isolated yields.
Determined by H NMR spectroscopy.
Complex mixture.
1
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Iodine-Catalyzed Intramolecular Oxidative Thiolation
Table 2. I2-catalyzed cyclization of 1.[a]
Entry
1
R
R1
R2
R3
Time [h]
Yield of 2+3 [%][b]
Ratio 2:3[c]
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
1o
1p
1q
1r
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Me
Bn
Et
Me
Et
Et
Et
-(CH2)2-
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
2-MeOC6H4
4-FC6H4
Ph
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Ph
H
8
98
94
90
68
92
63
92
98
96
64
85
99
94
94
84
97
62
52
73
79
92:8
82:18
97:3
95:5
91:9
85:15
91:9
91:9
95:5
97:3
94:6
93:7
98:2
95:5
91:9
98:2
96:4
97:3
92:8
94:6
–
4-MeC6H4
4-ClC6H4
2,3-CH2O2C6H3
2-ClC6H4
2-furyl
10
10
18
10
10
10
12
26
23
12
10
22
16
15
11
9
Ph
Ph
9
4-FC6H4
4-FC6H4
4-FC6H4
4-ClC6H4
4-MeOC6H4
2,3-CH2O2C6H3
Ph
4-ClC6H4
2,3-CH2O2C6H3
Ph
Ph
Ph
t-Bu
Ph
10
11
12
13
14
15
16
17
18
19
20
21
22
23
4-ClC6H4
4-ClC6H4
4-ClC6H4
4-BrC6H4
4-ClC6H4
4-MeOC6H4
4-MeOC6H4
Me
PhCO
H
4-FC6H4
4-MeOC6H4
12
7
13
12
14
12
1s
1t
1u
1v
1w
4-MeOC6H4
4-ClC6H4
Ph
[d]
–
43
–
–
[e]
Ph
–
[a]
Reaction conditions: 1 (0.2 mmol), I2 (0.02 mmol), DMSO (2 mL).
[b]
[c]
[d]
[e]
Isolated yields.
Determined by H NMR spectroscopy.
1
Complex mixture.
No desired cyclic product was obtained. 1w was recovered in 88% yield.
in 79% yield (entry 20). However, we found that the B. Alkyl iodide is released with the assistance of
reaction is sensitive to the ketene dithioacetal 1u iodide anion, resulting in iodocyclization product C.
without any substituent at the a-position and a com- Finally, 2-methylene-3-thiophenones 2 are smoothly
plex mixture was often obtained on using the present afforded via dehydroiodination. In this process, I2 can
protocol (entry 21). For the substrate 1v bearing two be regenerated by the corresponding oxidation of
substituents at the b-position, a diminished yield of 2v both hydrogen iodide and alkyl iodide in DMSO to
was obtained likely due to the steric hindrance of the complete the catalytic cycle.[19]
b-position (entry 22). The six-ring cyclic isomeric
product could not be formed in this case. Finally, we
During the reaction, we did not detect the iodocy-
ACHTUNGTRENcNGNU lization products C in any of the cases. We postulate
investigated the cyclization of ketene cyclic dithioace- that the easier elimination of HI even under neutral
tal 1w under the catalysis of iodine. But no desired conditions and at room temperature is likely due to
cyclic product was obtained after 12 h (entry 23).
the formation of the stable products 2 with an enone
On the basis of the experimental results and I2- conjugate structure (C!2).[20] The regioselectivity of
mediated transformations in DMSO reported in the the cyclization is well in accordance with Baldwinꢀs
literature,[17f,18] the reaction mechanism is understood rule[21] and the exo-trig type of cyclization (A!B!
in terms of the I2-catalytic cycle shown in Scheme 2. C!2) is observed to be more highly favored than the
Initially, iodonium A is formed from the substrates endo-trig type of cyclization (A!!3). Each product
1 in the presence of I2. Thereby, the intramolecular 2 was also isolated as a stereoisomer with a trans rela-
attack of nucleophilic alkylthio on the iodonium tionship of the R2 and carbonyl. No cis-isomers were
moiety via an exo manner leads to cyclic intermediate detected from the crude products. This indicates
Adv. Synth. Catal. 2014, 356, 743 – 748
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745

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Gang Zheng et al.
and its isomer 6a but only in 22% yield. The reaction
yield was improved to 73% by increasing the amount
of iodine to 50 mol% under otherwise identical condi-
tions (entry 1). However, a stoichiometric amount of
iodine decreased the reaction yield along with the for-
mation of complex by-products. Thus, other substrates
4b–f were selected toward the cyclization by using
50 mol% of iodine as catalyst. As shown in Table 3,
the corresponding cyclic products 5b–f along with
their regioisomers 6b–f were isolated in 40–62%
yields (entries 2–6).
ꢀ
In conclusion, a transition metal-free vinylic C H
thiolation process has been developed. Under the cat-
alysis of iodine (10 mol%), the cyclization of a-alk-
AHCTUNGTREGeNNNU noyl ketene dithioacetals via tandem iodocyclization
and dehydroiodination occurs successfully in terms of
the selectivity, product yields, and tolerance to
a range of functional groups. The synthetic strategy
provides an efficient and easy entry to polyfunc-
tionalized 2-methylene-3-thiophenones and can be ex-
tended to the synthesis of 2-methylene-3-benzothio-
Scheme 2. Proposed mechanism for the cyclization of 1.
a trans-elimination process of HI (C!2). Additional- phenones via the cyclization of ortho-methylthiophen-
ly, the alkylthio group as a sulfur nucleophile in our yl vinyl ketones. The alkylthio functional group re-
work can avoid the formation of disulfides as accom- tained in the products should enable potential trans-
panying products. All of the above factors may con- formations based on it.[22] Further investigations on
tribute to the efficient conversions of ketene dithio- applications are in progress in our research group.
ACHTUNGTRENNUNGacetals 1 to cyclic products 2. Thus, we provide here
a practical cyclization strategy for the synthesis of thi-
ophenone derivatives 2 from easily prepared starting
materials.
Experimental Section
Encouraged by the above experimental results, we
next tried to extend the cyclization to ortho-methyl-
thiophenyl vinyl ketones for the synthesis of benzo-
thiophenones (Table 3). As we expected, upon treat-
ment of 4a with 10 mol% of iodine in DMSO at
1508C, the cyclization could took place to give the de-
Typical Procedure
To a 25-mL round-bottom flask was added 1a (77 mg,
0.2 mmol), I2 (5.0 mg, 0.02 mmol) and DMSO (2 mL). The
reaction mixture was stirred at 1508C until 1a was consumed
under the monitoring of TLC. The resulting mixture was
poured into dilute aqueous Na2S2O3 solution (20 mL), and
sired mixture of 2-methylenebenzothiophen-3-one 5a extracted with CH2Cl2 (3ꢂ10 mL). The combined organic
Table 3. Synthesis of benzothiophenones via I2-catalyzed cyclization of 4.[a]
Entry
4/R1, R2
Time [h]
Yield of 5+6 [%][b]
Ratio 5:6[c]
1
2
3
4
5
6
4a/H, Ph
12
12
11
10
8
73
58
56
62
44
40
90:10
90:10
81:19
94:6
93:7
73:27
4b/H, 4-MeC6H4
4c/H, 4-MeOC6H4
4d/H, 2,3-CH2O2C6H3
4e/F, Ph
4f/F, 4-ClC6H4
10
[a]
Reaction conditions: 4 (0.2 mmol), I2 (0.5 equiv.), DMSO (2 mL).
[b]
[c]
Isolated yields.
1
Determined by HNMR spectroscopy.
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Iodine-Catalyzed Intramolecular Oxidative Thiolation
extracts were washed with water (3ꢂ10 mL), dried over an-
hydrous MgSO4, filtered and concentrated under reduced
pressure to yield the crude product, which was purified by
silica gel chromatography (eluent, petroleum ether/ethyl
acetate: 50/1, v/v) to give a mixture of 2a and 3a as a yellow
solid; yield: 68.5 mg (98%). Pure 2a was obtained by an ad-
ditional careful chromatography.
Zhang, K. C. Ngeow, J. Y. Ying, Org. Lett. 2007, 9,
3495.
[4] For recently selected examples on the hydrothiolation
of alkynes, see: a) K. Liu, F. Jia, H. Xi, Y. Li, X.
Zheng, Q. Guo, B. Shen, Z. Li, Org. Lett. 2013, 15,
2026; b) A. D. Giuseppe, R. Castarlenas, J. J. Pꢃrez-Tor-
rente, M. Crucianelli, V. Polo, R. Sancho, F. J. Lahoz,
L. A. Oro, J. Am. Chem. Soc. 2012, 134, 8171; c) S.
Ranjit, Z. Duan, P. Zhang, X. Liu, Org. Lett. 2010, 12,
4134; d) Z. Duan, S. Ranjit, P. Zhang, X. Liu, Org.
Lett. 2010, 12, 2430; e) C. J. Weiss, T. J. Marks, J. Am.
Chem. Soc. 2010, 132, 10533; f) Q. Ding, X. He, J. Wu,
J. Comb. Chem. 2009, 11, 587.
[5] For representative recent reviews, see: a) C. I. Herre-
rꢄas, X. Yao, Z. Li, C.-J. Li, Chem. Rev. 2007, 107, 2546;
b) T. W. Lyons, M. S. Sanford, Chem. Rev. 2010, 110,
1147; c) D. A. Colby, R. G. Bergman, J. A. Ellman,
Chem. Rev. 2010, 110, 624; d) P. B. Arockiam, C. Bru-
neau, P. H. Dixneuf, Chem. Rev. 2012, 112, 5879;
e) S. R. Neufeldt, M. S. Sanford, Acc. Chem. Res. 2012,
45, 936; f) M. S. Sigman, E. W. Werner, Acc. Chem.
Res. 2012, 45, 874; g) K. M. Engle, T.-S. Mei, M. Wasa,
J.-Q. Yu, Acc. Chem. Res. 2012, 45, 788; h) B. G. Hashi-
guchi, S. M. Bischof, M. M. Konnick, R. A. Periana,
Acc. Chem. Res. 2012, 45, 885.
[6] a) C. Yu, C. Zhang, X. Shi, Eur. J. Org. Chem. 2012,
1953; b) S. Ranjit, R. Lee, D. Heryadi, C. Shen, J. Wu,
P. Zhang, K. Huang, X. Liu, J. Org. Chem. 2011, 76,
8999; c) A. Zhou, X. Liu, K. Yang, S. Zhao, Y. Liang,
Org. Biomol. Chem. 2011, 9, 5456; d) S. Zhang, P.
Qian, M. Zhang, M. Hu, J. Cheng, J. Org. Chem. 2010,
75, 6732.
[7] a) C. Shen, H. Xia, H. Yan, X. Chen, S. Ranjit, X. Xie,
D. Tan, R. Lee, Y. Yang, B. Xing, K. Huang, P. Zhang,
X. Liu, Chem. Sci. 2012, 3, 2388; b) K. Inamoto, K.
Nozawa, Y. Kondo, Synlett 2012, 10, 1678; c) J. Zhu, Z.
Chen, H. Xie, S. Li, Y. Wu, Org. Lett. 2010, 12, 2434;
d) K. Inamoto, C. Hasegawa, J. Kawasaki, K. Hiroya,
T. Doi, Adv. Synth. Catal. 2010, 352, 2643; e) K. Inamo-
to, C. Hasegawa, J. Kawasaki, K. Hiroya, T. Doi, Org.
Lett. 2008, 10, 5147; f) K. Inamoto, Y. Arai, K. Hiroya,
T. Doi, Chem. Commun. 2008, 5529.
Acknowledgements
We gratefully acknowledge National Natural Sciences Foun-
dation of China (21172031 and 21372040), New Century Ex-
cellent Talents in Chinese University (NCET-11-0613) and
Research Fund for the Doctoral Program of Higher Educa-
tion of China (20120043110004) for financial support.
References
ꢀ
[1] For selected reviews on C S bond formation, see: a) T.
Kondo, T.-A. Mitsudo, Chem. Rev. 2000, 100, 3205;
b) S. V. Ley, A. W. Thomas, Angew. Chem. 2003, 115,
5558; Angew. Chem. Int. Ed. 2003, 42, 5400; c) I. P. Be-
letskaya, V. P. Ananikov, Eur. J. Org. Chem. 2007, 3431;
d) I. P. Beletskaya, V. P. Ananikov, Chem. Rev. 2011,
111, 1596; e) C. C. Eichman, J. P. Stambuli, Molecules
2011, 16, 590; f) H. Liu, X. Jiang, Chem. Asian J. 2013,
8, 2546.
[2] For selected examples of the applications, see: a) F. J.
Robertson, J. Wu, J. Am. Chem. Soc. 2012, 134, 2775;
b) D. H. Scharf, N. Remme, A. Habel, P. Chankhamjon,
K. Scherlach, T. Heinekamp, P. Hortschansky, A. A.
Brakhage, C. Hertweck, J. Am. Chem. Soc. 2011, 133,
12322; c) B. Jiang, H. Tian, A.-G. Huang, M. Xu, Org.
Lett. 2008, 10, 2737; d) K. Oh, Org. Lett. 2007, 9, 2973;
e) C. S. Bryan, J. A. Braunger, M. Lautens, Angew.
Chem. 2009, 121, 7198; Angew. Chem. Int. Ed. 2009, 48,
7064; f) B. Gabriele, R. Mancuso, G. Salerno, R. C.
Larock, J. Org. Chem. 2012, 77, 7640; g) Q. Zhao, L.
Li, Y. Fang, D. Sun, C. J. Li, J. Org. Chem. 2009, 74,
459; h) H. Mizuno, K. Domon, K. Masuya, K. Tanino,
I. Kuwajima, J. Org. Chem. 1999, 64, 2648.
[3] For recently selected examples on the cross-coupling
reactions of thiols and aryl/vinyl halides, see: a) Y.-Y.
Lin, Y.-J. Wang, C.-H. Lin, J.-H. Cheng, C.-F. Lee, J.
Org. Chem. 2012, 77, 6100; b) Q. Liao, C. Xi, Chin. J.
Org. Chem. 2012, 32, 986; c) H.-L. Kao, C.-F. Lee, Org.
Lett. 2011, 13, 5204; d) W. You, X. Yan, Q. Liao, C. Xi,
Org. Lett. 2010, 12, 3930; e) M. S. Kabir, M. Lorenz,
M. L. Van Linn, O. A. Namjoshi, S. Ara, J. M. Cook, J.
Org. Chem. 2010, 75, 3626; f) M. S. Kabir, M. L. Van
Linn, A. Monte, J. M. Cook, Org. Lett. 2008, 10, 3363;
g) C.-K. Chen, Y.-W. Chen, C.-H. Lin, H.-P. Lin, C.-F.
Lee, Chem. Commun. 2010, 46, 282; h) V. P. Reddy,
A. V. Kumar, K. Swapna, K. R. Rao, Org. Lett. 2009,
11, 1697; i) E. Sperotto, G. P. M. van Klink, J. G.
de Vries, G. van Koten, J. Org. Chem. 2008, 73, 5625;
j) A. Correa, M. Carril, C. Bolm, Angew. Chem. 2008,
120, 2922; Angew. Chem. Int. Ed. 2008, 47, 2880; k) Y.
[8] a) H. Wang, L. Wang, J. Shang, X. Li, H. Wang, J. Gui,
A. Lei, Chem. Commun. 2012, 48, 76; b) M. L. Zhang,
S. H. Zhang, C. D. Pan, F. Chen, Synth. Commun. 2012,
42, 2844; c) X. L. Fang, R. Y. Tang, X. G. Zhang, J. H.
Li, Synthesis 2011, 1099.
[9] L. Zou, J. Reball, J. Mottweiler, C. Bolm, Chem.
Commun. 2012, 48, 11307.
[10] a) M. T. Bresser, P. Knochel, Angew. Chem. 2011, 123,
1954; Angew. Chem. Int. Ed. 2011, 50, 1914; b) P. J. E.
Verdegem, M. C. F. Monnee, J. Lugtenburg, J. Org.
Chem. 2001, 66, 1269; c) L. Brandsma, H. D. Verk-
ruijsse, C. Schade, P. von R. Schleyer, J. Chem. Soc.
Chem. Commun. 1986, 260; d) J.-C. Clinet, C. Linstru-
melle, Synthesis 1981, 875.
[11] Y. Masaki, K. Sakuma, K. Kaji, Chem. Lett. 1979, 1235.
[12] a) H. Takahata, K. Moriyama, M. Maruyama, T. Yama-
zaki, J. Chem. Soc. Chem. Commun. 1986, 1671;
b) N. F. Haley, M. W. Fichtner, J. Org. Chem. 1980, 45,
2959.
Adv. Synth. Catal. 2014, 356, 743 – 748
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
747

COMMUNICATIONS
Gang Zheng et al.
[13] For selected reviews, see: a) L. Pan, X. Bi, Q. Liu,
Chem. Soc. Rev. 2013, 42, 1251; b) L. Pan, Q. Liu, Syn-
lett 2011, 1073.
Org. Lett. 2012, 14, 3392; h) Z. He, W. Liu, Z. Li,
Chem. Asian J. 2011, 6, 1340.
[18] a) M. Gao, Y. Yang, Y. D. Wu, C. Deng, W. M. Shu,
D. X. Zhang, L. P. Cao, N. F. She, A. X. Wu, Org. Lett.
2010, 12, 4026; b) G. Yin, B. Zhou, X. Meng, A. Wu, Y.
Pan, Org. Lett. 2006, 8, 2245; c) W. Ge, Y. Wei, Green
Chem. 2012, 14, 2066.
[19] We could detect Me2S by the HR-MS (ESI) study of
the reaction mixture when the reaction was performed
in a sealed vial under the same reaction conditions
([Me2S+Na]+, calculated: 85.0082, found: 85.0547,
samples were taken 5 h after stirring at 1508C, cooled
and diluted with MeCN prior to the direct injection
into the mass spectrometer); a) T. Aida, N. Furukawa,
S. Oae, Tetrahedron Lett. 1973, 14, 3853; b) T. Aida, T.
Akasaka, N. Furukawa, S. Oae, Bull. Chem. Soc. Jpn.
1976, 49, 1117.
[14] For cyclization strategies based on a-alkenoyl ketene
dithioacetals 1 recently developed by us, see: a) B. Liu,
G. Zheng, X. Liu, C. Xu, J. Liu, M. Wang, Chem.
Commun. 2013, 49, 2201; b) M. Wang, F. Han, H.
Yuan, Q. Liu, Chem. Commun. 2010, 46, 2247; c) M.
Wang, Z. Fu, F. Han, Y. Dong, J. Liu, Q. Liu, Chem.
Commun. 2010, 46, 9061; d) Z. Fu, M. Wang, Y. Dong,
J. Liu, Q. Liu, J. Org. Chem. 2009, 74, 6105; e) Y. Ma,
M. Wang, D. Li, B. Bekturhun, J. Liu, Q. Liu, J. Org.
Chem. 2009, 74, 3116.
[15] For selected reviews, see: a) M. J. Mphahlele, Molecules
2009, 14, 4814; b) B. Godoi, R. F. Schumacher, G. Zeni,
Chem. Rev. 2011, 111, 2937; c) P. T. Parvatkar, P. S. Par-
ameswaran, S. G. Tilve, Chem. Eur. J. 2012, 18, 5460.
[16] Crystal data for 2a: C20H18O2S2, yellow, M=354.46,
monoclinic, space group P21/n, a=6.164(5) ꢅ, b=
23.928(5) ꢅ, c=12.121(5) ꢅ, V=1765.5(16) ꢅ3, a=
90.000(5)8, b=99.050(5)8, g=90.000(5)8, Z=4, T=
293(2) K, F000=744, 6666 reflections collected, 3103
[20] In order to get more information on the mechanism,
we examined the I2-catalyzed cyclization of a-benzoyl,
a-allyl ketene dimethyl thioacetal. It was found that
unique with RACHTUNRGTEN(UNG int)=0.0162, R1 =0.0336, wR2 =0.0825
[I>2 s(I)]. CCDC 947706 contains the supplementary
crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
the iodocyclization product could be isolated in 37%
yield along with the recovery of starting material in
51% yield when the reaction was performed in DMSO
in the presence of 1.2 equivalents of I2 at room temper-
ature. The reaction mixture became complex at 1508C
with 0.1 equivalent of I2 as catalyst. For details, please
see the Supporting Information.
[17] For recent selected examples, see: a) F.-L. Yang, S.-K.
Tian, Angew. Chem. 2013, 125, 5029; Angew. Chem.
Int. Ed. 2013, 52, 4929; b) J. Dhineshkumar, M.
Lamani, K. Alagiri, K. R. Prabhu, Org. Lett. 2013, 15,
1092; c) Y. C. Teo, S. N. Riduan, Y. Zhang, Green
Chem. 2013, 15, 2365; d) Y. Yan, Y. Zhang, C. Feng, Z.
Zha, Z. Wang, Angew. Chem. 2012, 124, 8201; Angew.
Chem. Int. Ed. 2012, 51, 8077; e) H. Batchu, S. Bhatta-
charyya, S. Batra, Org. Lett. 2012, 14, 6330; f) Y.-P.
Zhu, M. Lian, F.-C. Jia, M.-C. Liu, J.-J. Yuan, Q.-H.
Gao, A.-X. Wu, Chem. Commun. 2012, 48, 9086; g) Y.
Zhu, M. Liu, F. Jia, J. Yuan, Q. Gao, M. Lian, A. Wu,
[21] J. E. Baldwin, J. Chem. Soc. Chem. Commun. 1976,
734.
[22] a) Y. Dong, M. Wang, J. Liu, W. Ma, Q. Liu, Chem.
Commun. 2011, 47, 2080; b) Y. Liu, M. Wang, H. Yuan,
Q. Liu, Adv. Synth. Catal. 2010, 352, 884.
748
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Adv. Synth. Catal. 2014, 356, 743 – 748