Nitrogen dioxide-catalyzed electrophilic iodination of arenes

Article abstract of DOI:10.1002/adsc.201300581

Nitrogen dioxide is demonstrated to be an effective catalyst precursor for the iodination of alkoxy-substituted benzenes and naphthalenes. Different from the transition metal catalysts, nitrogen dioxide can be easily separated from the final products, and is free of heavy metal waste. Although the present catalyst precursor is toxic, it does not stain the final products due to its low-boiling character. No other reagents apart from 0.5 equiv. of iodine (I ₂), 6.5 mol% nitrogen dioxide and acetonitrile solvent were used in the iodination, and basically all the iodine atoms in the iodine source were transferred to the iodination products, showing that the presented protocol is highly atom-economic and practical. Copyright

Full text of DOI:10.1002/adsc.201300581

FULL PAPERS
DOI: 10.1002/adsc.201300581
Nitrogen Dioxide-Catalyzed Electrophilic Iodination of Arenes
Yun-Lai Ren,a Huantao Shang,a Jianji Wang,a,b,* Xinzhe Tian,a Shuang Zhao,a
Qian Wang,a and Fuwei Lic
a
School of Chemical Engineering & Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471003,
Peopleꢀs Republic of China
Fax : (+86)-379-6421-0415; e-mail: Jwang@henannu.edu.cn
School of Chemistry and chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of
b
Education, Henan Normal University, Xinxiang, Henan 453007, Peopleꢀs Republic of China
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese
c
Academy of Sciences, Lanzhou, Gansu 730000, Peopleꢀs Republic of China
Received: June 30, 2013; Revised: August 24, 2013; Published online: November 8, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300581.
Abstract: Nitrogen dioxide is demonstrated to be an (I2), 6.5 mol% nitrogen dioxide and acetonitrile sol-
effective catalyst precursor for the iodination of vent were used in the iodination, and basically all
alkoxy-substituted benzenes and naphthalenes. Dif- the iodine atoms in the iodine source were trans-
ferent from the transition metal catalysts, nitrogen ferred to the iodination products, showing that the
dioxide can be easily separated from the final prod- presented protocol is highly atom-economic and
ucts, and is free of heavy metal waste. Although the practical.
present catalyst precursor is toxic, it does not stain
the final products due to its low-boiling character. Keywords: arenes; catalysis; iodination; nitrogen di-
No other reagents apart from 0.5 equiv. of iodine oxide
Introduction
strategy where the electrophilic I+-type species is gen-
erated through oxidation of iodine sources by
Aryl iodides have served as versatile intermediates oxidizing reagent systems, for example, CrO3,[11]
for the synthesis of various organic products because Pb
(OAc)4,[12] Ce(OTf)4,[13] hydrogen peroxide,[14]
ACHUTGTNRENNUG CAHTUNGTRENNUGN
they are excellent substrates for the formation of H5IO6,[15] peroxodisulfate salts,[16] and ferrate salts.[17]
carbon-carbon and carbon-heteroatom bonds via tran-
The use of molecular oxygen as the oxidant is a still
sition metal-catalyzed cross-coupling reactions.[1] As desirable goal from environmental and economic per-
a result, much effort has been devoted to the develop- spectives.[18] Neumann and co-workers reported an ef-
ment of effective methods for the introduction of the fective method for the aerobic iodination of arenes
iodo functional group onto aromatic rings.[2–5] Aryl io- via H5PV2Mo10O40-catalyzed oxidation of molecular
dides can be synthesized via iodo-deboronation of ar- iodine by oxygen gas.[19] Subsequently, the Bi
ACHTUNTGRENUNG(NO3)3-
ylboron compounds,[2] halogen exchange of aryl hal- BiCl3 system was found to be an effective catalyst for
ides[3] or the Sandmeyer reaction from aromatic the aerobic iodination under an air atmosphere.[20] In
amines.[4] In contrast, electrophilic iodination of aro- 2007, Das and co-workers reported the ceric ammoni-
matic compounds seems to be a more attractive alter- um nitrate-catalyzed aerobic iodination of arenes,[21]
native to the synthesis of aryl iodides due to the use but such a reaction required the use of 1 equivalent of
of readily available substrates.[6] Different from chlor- I2, thus a half of iodine source was wasted. Other ex-
ine and bromine, iodine is less reactive towards most amples relative to the aerobic iodination of arenes
aromatic compounds, thus electrophilic iodination re- are the reactions using I2/NaNO2/air/silica-supported
quires the presence of the more reactive species with H2SO4 or KI/air/NaNO2/H2SO4.[23] Considering the
[22]
a pronounced I+ character. One of the most effective fact that NO2 is free of heavy metal waste and easily
solutions to this situation is the use of iodonium separated from the final products, our attention was
equivalents (I+), for example, N-iodosuccinimide,[7] N- directed to developing a procedure with NO2 as the
iodosaccharin,[8] iodine monochloride[9] and IOAc.[10] catalyst precursor for the aerobic iodination, and the
Another effective solution is the oxidative activation results are reported herein.
Adv. Synth. Catal. 2013, 355, 3437 – 3442
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3437

Yun-Lai Ren et al.
FULL PAPERS
Results and Discussion
atom source ends up in the final products.[21,27] Ac-
cording to the law of charge conservation, the reac-
Our initial study aimed at the iodination of n-butoxy- tion requires the presence of an oxidizing reagent that
benzene as a model reaction to investigate the catalyt- plays a role of oxidizing the iodide molecule to the I+
ic efficiency of NO2. As shown in Scheme 1, the reac- species. It was noted that there were about 43 mL of
tion proceeded efficiently using as low as 6.5 mol% residual air (at atmospheric pressure) in the reaction
NO2 and gave the desired product in a high yield, tube before the reaction system was heated. Thus it is
along with a small amount of 4-nitro-4-n-butoxyben- rational to assume that the residual oxygen in the re-
zene by-product resulting from the nitration of the action tube serves as the oxidizing reagent. Indeed,
benzene ring.[24] Although the n-butoxy group is an the removal of oxygen from the reaction system re-
ortho-para directing group, only a small amount of sulted in a remarkable decrease in the product yield
ortho-iodination product was observed. Such an ex- (Supporting Information, Table S3, entry 7). The iodi-
clusive regioselectivity was also mentioned in several nation reaction could proceed smoothly when the
reports[25] where bromination of methoxybenzene and concentration of oxygen was decreased to 15 vol%,
cyanation of multi-substituted benzenes were per- but a further decrease of the oxygen concentration to
formed. As described in the literature,[25a] the exact 10 vol% led to a lower yield (Supporting Information,
reason for this excellent selectivity is not clear at the Table S3, entries 4 and 5). Consistent with
present stage. However, the steric effect seems to be H5PV2Mo10O40-catalyzed iodination of arenes,[19] the
one of the main reasons: the larger steric hindrance use of IÀ in place of I2 did not result in significant io-
of the position ortho to the alkoxy group leads to less dination (Supporting Information, Table S2, en-
ortho-product,[26] and allows the reaction to give tries 12–14), which suggested that no electrophilic I+
a high para-selectivity.
species was formed from the formation and then oxi-
The reaction was highly dependent on the loading dation of IÀ under our experimental conditions using
amount of NO2: the aromatic substrate was less reac- molecular iodine, thus it was possible that the molecu-
tive in the absence of NO2, and the optimal results lar iodine was directly oxidized to two I+-type spe-
were obtained in the case of 4.8–7.2 mol% NO2 (see cies.[19]
Table S2 in the Supporting Information). It is worth
With the optimized conditions in hand, we set out
noting that an increase of the catalyst loading facili- to evaluate the scope of the present iodination proto-
tates the nitration of the benzene ring, which leads to col. When the mono-substituted benzenes containing
a decrease in the yield of the iodination product. For alkoxy groups were employed as the substrates
example, when the loading amount of NO2 increased (Table 1, entries 1–8), all the iodination reactions pro-
from 2.4 to 9.6 mol%, the yield of nitration product ceeded efficiently with high yields and high para-se-
increased from 0 to 3.7% (Supporting Information, lectivities. Surprisingly, the phenyl rings with other ac-
Table S2, entries 3–9). The type of solvent was found tivated groups were converted into the desired prod-
to have an important effect on the iodination. Of the ucts in poor yields (see Table S4 in the Supporting In-
screened solvents, acetonitrile was highly effective, formation). One can argue that the alkoxy groups are
while the iodinations using toluene, N,N- stronger aromatic activating groups,[25b,28] and there-
dimethylformACHTUNGTRENNUNGamide, and N-methylpyrrolidone were fore this might be an explanation for the ease of iodi-
very sluggish. Although dimethyl sulfoxide was also nation of alkoxybenzenes. However, it is difficult to
effective as the solvent (Supporting Information, understand why only alkoxyphenyl rings among so
Table S2, entry 18), we preferred the low-boiling ace- many types of electron-rich phenyl rings showed such
tonitrile because the use of high-boiling solvent was high reactivities. Although the present method was
disadvantageous for the separation and purification of limited to the iodinations of the benzenes with alkoxy
the products.
groups, it was compatible with various groups includ-
It was not necessary to use an excess of I2. Hence, ing alkyl, acetamido, ester, carboxyl, nitro, chloro,
basically all the iodine atoms could be transferred to bromo and iodo groups (Scheme 2), which seems to
the iodination product. This highly atom-economic offer an opportunity for the selective functionaliza-
character contrasts sharply with that of the previous tion of the alkoxybenzene rings in the case of the sub-
methods where only a low percentage of the iodine
Scheme 1. NO2-catalyzed iodination of n-butoxybenzene.
3438
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3437 – 3442

Nitrogen Dioxide-Catalyzed Electrophilic Iodination of Arenes
Table 1. NO2-catalyzed iodination of various alkoxy-substi-
tries 9–16), even the alkoxybenzene with a deactivat-
ing substituent was iodinated in moderate yield
(Table 1, entry 16). In addition, the regioselectivity
was excellent and the iodination of the tested disub-
stituted benzenes selectively occurred at the para-po-
tuted benzenes and naphthalenes.[a]
À
sition with regard to alkoxy group. If the para C H
bonds of alkoxybenzenes were absent, it was difficult
for the iodination to proceed efficiently. For example,
4-methoxytoluene underwent this transformation in
poor yield (Table 1, entry 17), while the reaction se-
lectivity was excellent and scarcely any other product
was observed besides 3-iodo-4-methoxytoluene. Inter-
estingly, 2,3,4-trimethoxy-1-iodobenzene, a key inter-
mediate used in the manufacture of trimetazidines
and some kinase inhibitor drugs,[29] was synthesized
from 1,2,3-trimethoxybenzene by using the present
procedure (Table 1, entry 20). Another kind of good
substrate were the alkoxynaphthalenes (Table 21, en-
tries 21–24), among which 1-alkoxynaphthalene was
selectively iodinated at its 4-position, while 2-alkoxy-
naphthalene underwent this transformation at its 1-
position. The same site-selectivity was also observed
in the bismuth-catalytic iodination with molecular
iodine.[20] We tried the iodination of several aromatic
heterocycles including 1-methylimidazole, benzofuran,
benzothiazole, indole and 2-phenylpyridine, but only
a trace or small amount of iodination products was
observed (Supporting Information, Table S4, en-
tries 31–34).
At the end of reaction, only a small amount of NO2
and other impurities were present in the solution of
the resulting product, which offers an opportunity to
further convert the iodine group to other functional
groups in a one-pot process. As shown in Table 2, sev-
eral benzonitrile products were effectively synthesized
through the one-pot iodination and cyanation se-
quence.
Finally, our attention was drawn to the investigation
of the catalytic species. NO2 or its dimer can be dilut-
ed with many solvents to give small amounts of NO+
and NO3 in some cases (Scheme 3).[30] The resulting
À
NO+ seems to be the real catalytic species because
the oxidation of iodine to I+ is possibly carried out by
NO+ in an inner-sphere electron transfer step,[31]
which was also confirmed by our experimental result:
the iodination with NOBF4 instead of NO2 proceeded
efficiently with a high yield (Scheme 4).
[a]
Reaction conditions: 0.5 mmol substrate, 0.25 mmol I2,
It is known that NO+ is effective in oxidizing
a number of aromatics and heteroaromatics to the
cation radicals,[32] hence the resulting aromatic radical
cations should react with another aryl ring to generate
the biaryl by-poducts.[33] However, no biaryl by-prod-
0.0325 mmol NO2, 1.5 mL acetonitrile, 10 h, the air in the
tube was not removed.
[b]
The product was characterized by 1H NMR and mass
spectroscopy.
strates containing two or more activated benzene uct was observed in all cases, which reveals that the
rings. mechanistic pathway via aryl radicals is ruled out
Among the tested disubstituted benzenes, ortho- under our experimental conditions (Scheme 5).
and meta-substituted alkoxybenzenes were found to Considering that it is possible that the molecular
be good substrates for the iodinations (Table 1, en- iodine is oxidized by NO+ to two I+-type species,[31]
Adv. Synth. Catal. 2013, 355, 3437 – 3442
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3439

Yun-Lai Ren et al.
FULL PAPERS
Scheme 2. Several competition reactions between methoxybenzene and some substituted benzenes (for the experimental
procedure, see Scheme S1 in the Supporting Information).
Table 2. Cyanation of several arenes through the one-pot io-
dination/cyanation.[a]
Scheme 5. Impossible mechanistic pathway.
I+ and phenyl ring gives the s-complex intermediate,
followed by an elimination of hydrogen to afford the
iodobenzene product.[6a,34] It is worth noting that, al-
though the elimination of hydrogen generates H+
ions, the pH value of the reaction mixture is close to
7.0 after the completion of the reaction, which is pos-
sibly rationalized by assuming that the resulting H+
ion is consumed in the oxidation of NO to NO+.
[a]
For the experimental procedure, see Table S5 in the Sup-
porting Information.
Conclusions
In conclusion, an effective method was developed for
a tentatively proposed mechanism pathway is present- the iodination of alkoxy-substituted benzenes and
ed in Scheme 6. NO+ plays the role of a mediator to naphthalenes with nitrogen dioxide as the catalyst
bridge the gap between oxygen and I2 to generate an precursor. The used nitrogen dioxide can be easily
electrophilic I+ species.[31] Then the reaction between separated from the final products, and is free of heavy
metal waste. Although the present catalyst precursor
is toxic, it does not stain the final products due to the
low-boiling character. No other reagents apart from
0.5 equiv. I2, 6.5 mol% nitrogen dioxide and acetoni-
trile solvent were used in the iodination, and basically
all the iodine atoms could be transferred to the iodi-
nation products, indicating that the presented proto-
col is atom-economic and practical. Interestingly,
Scheme 3. Considerations on the catalytic species.
among various phenyl hydrogens, those at the para-
position with regard to alkoxy groups were selectively
iodinated in excellent yields. In addition, several ben-
zonitrile products were effectively synthesized
through the one-pot iodination and cyanation se-
quence. Preliminary mechanistic investigations sug-
Scheme 4. Iodination of methoxybenzene catalyzed by
NOBF4.
gest that the reaction presumably involves NO+ as
3440
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3437 – 3442

Nitrogen Dioxide-Catalyzed Electrophilic Iodination of Arenes
Scheme 6. Proposed mechanism for the iodination.
References
a mediator to bridge the gap between oxygen and I2
to generate an electrophilic I+ species.
[1] For recent reviews related to transition metal-catalyzed
cross-coupling reactions using aryl iodides, see a) M.
Pena-Lopez, L. A. Sarandeses, J. P. Sestelo, Eur. J. Org.
Chem. 2013, 2545; b) H. F. Sore, W. R. J. D. Galloway,
D. R. Spring, Chem. Soc. Rev. 2012, 41, 1845; c) H. B.
Li, C. C. C. J. Seechurn, T. J. Colacot, ACS Catal. 2012,
2, 1147; d) ꢃ. Molnꢄr, Chem. Rev. 2011, 111, 2251;
e) I. P. Beletskaya, V. P. Ananikov, Chem. Rev. 2011,
111, 1596; f) C. Liu, H. Zhang, W. Shi, A. W. Lei,
Chem. Rev. 2011, 111, 1780.
[2] For recent literatures related to iodo-deboronation of
arylboron compounds, see a) B. M. Partridge, J. F. Hart-
wig, Org. Lett. 2013, 15, 140; b) Y. L. Ren, X. Z. Tian,
C. H. Dong, S. Zhao, J. J. Wang, M. J. Yan, X. G. Qi,
G. H. Liu, Catal. Commun. 2013, 32, 15; c) G. Y.
Zhang, G. L. Lv, L. P. Li, F. Chen, J. Cheng, Tetrahe-
dron Lett. 2011, 52, 1993; d) H. J. Yang, Y. Li, M. Jiang,
J. M. Wang, H. Fu, Chem. Eur. J. 2011, 17, 5652.
[3] For several literatures related to halogen-exchange of
aryl halides, see a) T. D. Sheppard, Org. Biomol. Chem.
2009, 7, 1043; b) M. A. Lacour, M. Zablocka, C. Du-
hayon, J. P. Majoral, Adv. Synth. Catal. 2008, 350, 2677;
c) A. Klapars, S. L. Buchwald, J. Am. Chem. Soc. 2002,
124, 14844; d) W. B. Hardy, R. B. Fortenbaugh, J. Am.
Chem. Soc. 1958, 80, 1716.
[4] For recent literature related to diazotization-iodination
of arylamines, see a) F. Nemati, A. Elhampour, Sci.
Iran. 2012, 19, 1594; b) M. A. K. Zarchi, N. Ebrahimi,
J. Appl. Polym. Sci. 2011, 121, 2621; c) M. E. Trusova,
E. A. Krasnokutskaya, P. S. Postnikov, Y. Choi, K. W.
Chi, V. D. Filimonov, Synthesis 2011, 2154; d) A. Haji-
pour, F. Mohammadsaleh, Iran. J. Chem. Chem. Eng.
2011, 30, 23; e) A. R. Hajipour, M. Seddighi, Org. Prep.
Proced. Int. 2011, 43, 292; f) A. Zarei, A. R. Hajipour,
L. Khazdooz, Synthesis 2009, 941.
Experimental Section
For the quality and suppliers of the reagents see Table S1 in
the Supporting Information. n-Butoxybenzene, n-tetradecyl-
ACHTUNGTRENNUNGoxybenzene, 2-n-butoxytoluene, 3-n-butoxytoluene, 1,3-di-
methyl-2-ethoxylbenzene and 1-chloro-3-n-butoxybenzene
were obtained from the reactions between the correspond-
ing chloroalkanes and substituted phenols. Other chemicals
were commercially available and were used without further
1
purification. H NMR and 13C NMR spectra were recorded
on a Bruker 400 MHz or 500 MHz instrument with chemical
shifts reported in ppm relative to the internal standard tetra-
methylsilane. Gas chromatography analyses were performed
on a Varian CP-3800 instrument with an FID detector and
a CP-WAX 57CB FS capillary chromatographic column
(25 mꢂ0.32 mm). GC-MS were recorded on an Agilent
6890/5973N gas chromatography-mass spectrometry instru-
ment.
General Procedure for the Iodinations
0.5 mmol substrate, 0.25 mmol I2, 1.5 mL acetonitrile and
0.0325 mmol NO2 were added to a dried 45-mL tube
equipped with a magnetic stirring (note: NO2 was with-
drawn with a glass syringe from a flask filled with NO2, and
the air in the reaction tube was not removed). Then the re-
action tube was sealed and placed in a constant-temperature
oil bath to perform the reaction for 10 h. Once the reaction
time was reached, the mixture was cooled to room tempera-
ture. The iodination product was purified by column chro-
1
matography, and identified by H NMR and GC-MS.
Caution: Experiments using poisonous nitrogen dioxide
gas are potentially hazardous and must only be carried out
under rigorous safety precautions and using the appropriate
equipment to avoid gas leakage.
[5] For several reports related to iodination of arenes via
À
C H bond activation, see a) X. C. Wang, Y. Hu, S. Bo-
nacorsi, Y. Hong, R. Burrell, J. Q. Yu, J. Am. Chem.
Soc. 2013, 135, 10326; b) B. N. Du, X. Q. Jiang, P. P.
Sun, J. Org. Chem. 2013, 78, 2786; c) H. Aiso, T. Kochi,
H. Mutsutani, T. Tanabe, S. Nishiyama, F. Kakiuchi, J.
Org. Chem. 2012, 77, 7718; d) N. Schroeder, J. Wencel-
Delord, F. Glorius, J. Am. Chem. Soc. 2012, 134, 8298;
e) R. B. Bedford, M. F. Haddow, C. J. Mitchell, R. L.
Webster, Angew. Chem. 2011, 123, 5638; Angew. Chem.
Int. Ed. 2011, 50, 5524; f) T.-S. Mei, D.-H. Wang, J.-Q.
Yu, Org. Lett. 2010, 12, 3140.
Acknowledgements
The financial supports from the National Natural Science
Foundation of China (Grant No. 21002023) and the National
Basic Research Program of China (973 Program, Grant No.
2011CB211702) are greatly acknowledged.
[6] For representative reviews, see a) E. B. Merkushev,
Synthesis 1988, 923; b) C. Frota, G. A. Casagrande, L.
Pizzuti, R. C. Raminelli, Curr. Org. Synth. 2013, 10,
Adv. Synth. Catal. 2013, 355, 3437 – 3442
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3441

Yun-Lai Ren et al.
FULL PAPERS
265; c) V. V. K. M. Kandepi, N. Narender, Synthesis
2012, 44, 15.
[17] a) H. Keipour, M. A. Khalilzadeh, B. Mohtat, A. Hos-
seini, D. Zareyee, Chinese Chem. Lett. 2011, 22, 1427;
b) H. Tajik, A. Dadras, A. Hosseini, Synth. React.
Inorg. Met.-Org. Chem. 2011, 41, 258.
[18] For a recent review related to the aerobic iodination of
arenes with molecular oxygen as the oxidant, see A.
Podgorsek, M. Zupan, J. Iskra, Angew. Chem. 2009,
121, 8576; Angew. Chem. Int. Ed. 2009, 48, 8424.
[19] O. V. Branytska, R. Neumann, J. Org. Chem. 2003, 68,
9510.
[20] S. Wan, S. R. Wang, W. J. Lu, J. Org. Chem. 2006, 71,
4349.
[21] B. Das, M. Krishnaiah, K. Venkateswarlu, V. S. Reddy,
Tetrahedron Lett. 2007, 48, 81.
[22] J. Iskra, S. Stavber, M. Zupan, Tetrahedron Lett. 2008,
49, 893.
[23] G. Stavber, J. Iskra, M. Zupan, S. Stavber, Adv. Synth.
Catal. 2008, 350, 2921.
[24] a) P. M. Esteves, J. W. de M. Carneiro, S. P. Cardoso,
A. G. H. Barbosa, K. K. Laali, G. Rasul, G. K. S. Pra-
kash, G. A. Olah, J. Am. Chem. Soc. 2003, 125, 4836;
b) L. Chen, H. Xiao, J. Xiao, X. Gong, J. Phys. Chem.
A 2003, 107, 11440.
[25] a) J. Kim, J. Choi, K. Shin, S. Chang, J. Am. Chem. Soc.
2012, 134, 2528; b) S. R. K. Pingali, M. Madhav, B. S.
Jursic, Tetrahedron Lett. 2010, 51, 1383; c) P. K. Chhat-
tise, A. V. Ramaswamy, S. B. Waghmode, Tetrahedron
Lett. 2008, 49, 189.
[26] Y. L. Ren, M. J. Yan, S. Zhao, J. J. Wang, J. Y. Ma,
X. Z. Tian, W. P. Yin, Adv. Synth. Catal. 2012, 354,
2301.
[27] R. M. Al-Zoubi, D. G. Hall, Org. Lett. 2010, 12, 2480.
[28] C. Y. Zhou, J. Li, S. Peddibhotla, D. Romo, Org. Lett.
2010, 12, 2104.
[29] a) A. Maiti, P. V. N. Reddy, M. Sturdy, L. Marler, S. D.
Pegan, A. D. Mesecar, J. M. Pezzuto, M. Cushman, J.
Med. Chem. 2009, 52, 1873; b) T. Asano, T. Yoshikawa,
T. Usui, H. Yamamoto, Y. Yamamoto, Y. Ueharac, H.
Nakamura, Bioorg. Med. Chem. 2004, 12, 3529.
[30] C. C. Addison, Chem. Rev. 1980, 80, 21.
[31] A. D. Williamson, J. L. Beauchamp, J. Am. Chem. Soc.
1975, 97, 5714.
[32] a) B. K. Bandlish, H. J. Shine, J. Org. Chem. 1977, 42,
561; b) W. L. Musker, T. L. Wolford, J. Am. Chem. Soc.
1976, 98, 3055.
[33] a) H. Suzuki, Synthesis 1977, 217; b) L. Eberson, K.
Nyberg, Acc. Chem. Res. 1973, 6, 106.
[34] a) H. Gottam, T. K. Vinod, J. Org. Chem. 2011, 76, 974;
b) S. Adimurthy, G. Ramachandraiah, P. K. Ghosh,
A. V. Bedekar, Tetrahedron Lett. 2003, 44, 5099.
[7] a) W. A. Nack, G. He, S. Y. Zhang, C. X. Lu, G. Chen,
Org. Lett. 2013, 15, 3440; b) P. P. Singh, T. Thatikonda,
K. A. A. Kumar, S. D. Sawant, B. Singh, A. K. Sharma,
P. R. Sharma, D. Singh, R. A. Vishwakarma, J. Org.
Chem. 2012, 77, 5823; c) T. Kamei, M. Sako, K. Toriba-
take, T. Shimada, Tetrahedron Lett. 2012, 53, 3894; d) P.
Bovonsombat, J. Leykajarakul, C. Khan, K. Plaon,
M. M. Krause, P. Khanthapura, R. Ali, N. Doowa, Tet-
rahedron Lett. 2009, 50, 2664.
[8] a) L. Bailey, S. T. Handy, Tetrahedron Lett. 2011, 52,
2413; b) D. Dolenc, Synlett 2000, 544.
[9] a) S. Hamri, J. Rodriguez, J. Basset, G. Guillaumet,
M. D. Pujol, Tetrahedron 2012, 68, 6269; b) L. Emma-
nuvel, R. K. Shukla, A. Sudalai, S. Gurunath, S. Sivar-
am, Tetrahedron Lett. 2006, 47, 4793; c) A. K. Moha-
nakrishnan, C. Prakash, N. Ramesh, Tetrahedron 2006,
62, 3242; d) V. D. Filimonov, E. A. Krasnokutskaya,
Y. A. Lesina, Russ. J. Org. Chem. 2003, 39, 875.
[10] J. H. Ye, Z. J. Hu, Y. X. Wang, W. C. Zhang, Y. Zhang,
Tetrahedron Lett. 2012, 53, 6858.
´
[11] P. Lulinski, L. Skulski, Bull. Chem. Soc. Jpn. 1997, 70,
1665.
´
´
[12] B. Krassowska-swiebocka, P. Lulinski, L. Skulski, Syn-
thesis 1995, 926.
[13] N. Iranpoor, M. Shekarriz, Tetrahedron 2000, 56, 5209.
[14] a) L. Bedrac, J. Iskra, Adv. Synth. Catal. 2013, 355,
1243; b) L. Bedrac, J. Iskra, Tetrahedron Lett. 2012, 53,
5555; c) A. Hosseini, M. A. Khalilzadeh, H. Keipour,
M. Tajbakhsh, Synth. Commun. 2012, 42, 2407; d) R.
Sathiyapriya, Asian J. Chem. 2011, 23, 41; e) P. Carniti,
S. Colonna, A. Gervasini, Catal. Lett. 2010, 137, 55;
f) R. D. C. Gallo, K. S. Gebara, R. M. Muzzi, C. Rami-
nelli, Iran. J. Chem. Chem. Eng. 2010, 21, 770; g) M. M.
Kim, R. T. Ruck, D. Zhao, M. A. Huffman, Tetrahedron
Lett. 2008, 49, 4026; h) J. Pavlinac, M. Zupan, S. Stavb-
er, Acta Chim. Slov. 2008, 55, 841; i) K. S. K. Reddy, N.
Narender, C. N. Rohitha, S. J. Kulkarni, Synth.
Commun. 2008, 38, 3894.
[15] a) J. Yousefi-Seyf, K. Tajeian, E. Kolvari, N. Koukabi,
A. Khazaei, M. A. Zolfigol, Bull. Korean Chem. Soc.
2012, 33, 2619; b) M. A. Zolfigol, A. Khazaei, E. Kol-
vari, N. Koukabi, H. Soltani, M. Behjunia, Helv. Chim.
Acta 2010, 93, 587.
[16] a) N. C. Ganguly, S. K. Barik, S. Dutta, Synthesis 2010,
1467; b) R. Badri, M. Gorjizadeh, Chinese Chem. Lett.
2009, 20, 1439; c) H. Firouzabadi, N. Iranpoor, S.
Kazemi, Can. J. Chem. 2009, 87, 1675.
3442
asc.wiley-vch.de
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3437 – 3442