A new practical and highly efficient iodination of BODIPY derivatives with hypervalent iodine reagent

Article abstract of DOI:10.1016/j.tetlet.2012.10.040

A practical, convenient, and highly efficient mono- and diiodination of 1,3,5,7-tetramethyl BODIPY derivatives was achieved by using IOAc as the iodination reagent which was generated in situ from the mixture of phenyliodine(III) diactate with iodine. The

Full text of DOI:10.1016/j.tetlet.2012.10.040

Accepted Manuscript
A new practical and highly efficient iodination of BODIPY derivatives with
hypervalent iodine reagent
Jia-Hai Ye, Zhengjuan Hu, Yixin Wang, Whenchao Zhang, Yan Zhang
PII:
S0040-4039(12)01797-2
DOI:
http://dx.doi.org/10.1016/j.tetlet.2012.10.040
TETL 42002
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
18 August 2012
27 September 2012
9 October 2012
Please cite this article as: Ye, J-H., Hu, Z., Wang, Y., Zhang, W., Zhang, Y., A new practical and highly efficient
iodination of BODIPY derivatives with hypervalent iodine reagent, Tetrahedron Letters (2012), doi: http://
dx.doi.org/10.1016/j.tetlet.2012.10.040
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Graphical Abstract
A new practical and highly efficient
iodination of BODIPY derivatives with
hypervalent iodine reagent
Jia-Hai Ye, Zhengjuan Hu, Yixin Wang, Wenchao Zhang, Yan Zhang
Ar
Ar
B
Ar
PhI(OAc)
2 2
(2.0eq.)/I (2.2eq.)
PhI(OAc)
NaHCO
EtOH: CH
2
(0.48eq.)/I
2
(0.48eq.)
o
I
I
I
N
F
N
CH CN, r.t.
N
F
N
N
N
3
(1.5eq.), -25 C
3
B
B
CN(1:1, V:V)
F
F
F
F
3
68-78%
85-97%

1
Tetrahedron Letters
journal homepage: www.elsevier.com
A new practical and highly efficient iodination of BODIPY derivatives with
hypervalent iodine reagent
a,
a
a
a
b,
Jia-Hai Ye , Zhengjuan Hu , Yixin Wang , Whenchao Zhang , Yan Zhang *
a
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
School of Chemistry and Chemical Engineering, Key Lab of Analytical Chemistry for Life Science, Ministry of Education of China, Nanjing University,
b
Nanjing 210093, China
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A practical, convenient and highly efficient mono- and diiodination of 1,3,5,7-tetramethyl
BODIPY derivatives were achieved by using IOAc as the iodination reagent which was
generated in situ from the mixture of phenyliodine (III) diactate with iodine. The iodinated
reactions were performed smoothly to give the mono- or diiodination products in good to
excellent yields.
Available online
2012 Elsevier Ltd. All rights reserved.
Keywords:
Halogenation
Hypervalent iodine reagent
Selectivity
Fluorescent dye
4
,4-Difluoro-4-bora-3a,4a-diaza-s-indacene
7
, 11
most useful approaches to the photodynamic therapy reagents
1
. Introduction
and a good platform for the construction of extended π-electron
4
,5b,12
conjugation affording red-shifted BODIPY derivatives
through the transition-metal catalyzed reactions. To the best of
our knowledge, ICl, N-iodosuccinimide (NIS) and I -HIO
Over the past decades, there is increasing interest in the design,
preparation and functionality of BODIPY (4,4-Difluoro-4-bora-
a,4a-diaza-s-indacene or Boradiazaindacene) dyes in a wide
3
2
3
1
system have been utilized for the iodination of BODIPYs.
However; the above traditional methods suffer from some
drawbacks and limitations: the use of expensive, unstable or toxic
iodination reagents, higher reaction temperature and lower yields.
variety of research areas such as fluorescent switches, labeling
reagents, chemosensors, long-wavelength absorbing/emitting
fluorescent dyes, mesogenic materials,
polymers, light-harvesting systems, photodynamic therapy,
molecular logic systems, energy transfer cassettes and dye-
sensitized solar cells owing to their outstanding chemical,
thermal, and photophysical properties such as photostability,
large extinction coefficients, high luminescence efficiency, long
wavelength emission, reasonably long excited singlet state
lifetimes, relative insensitivity to environment perturbations, and
2
3
4
supramolecular
5
6
7
5c,12
8
Therefore, most people would agree that there is still room
9
for development of new functionalized methods of BODIPY
derivatives. We herein report a new practical, convenient and
more efficient approach for the mono- and diiodination of
,3,5,7-substituted BODIPYs at 2- or 2,6-positions which was
carried out with IOAc generated from the mixture of
1
4
,10
phenyliodine (III) diactate (PhI(OAc) , PIDA) with I2 in situ
high fluorescence quantum yields.
Recently, a number of
2
(
Scheme 1).
research groups demonstrated that BODIPY derivatives have
remarkably rich chemistry, making these dyes amenable to
chemical modifications4 at many positions of the
boradiazaindacene core. Among synthetic procedures for
functionalized BODIPYs, iodination of BODIPYs is one of the
Recently, IOAc was employed as an excellent iodination
reagent for the amidation or iodination of aromatic molecules,
alkenes and alkynes. Following these interesting development,
we envisioned that IOAc might be an useful iodonium source for
13
———
Corresponding author. Tel.: +86-25-84303116; fax: +86-25-8431-
857; e-mail: yejiahai@njust.edu.cn
5

2
Tetrahedron Letters
the efficient iodination of BODIPY derivatives. Initially, efforts
were focused on the optimization of the reaction of 1,3,5,7-
tetramethyl BODIPY 1a with I in the absence or in the presence
2 2
IOAc generated from the combination PhI(OAc) and I in situ
has proved to be an useful and highly efficient reagent for the
iodination of BODIPYs at their 2-/2,6-positions under mild
conditions. In addition to its practicability and efficiency, this
methodology also affords mono- and diiodination BODIPYs
selectively in good to excellent yields. This method provides an
easy access to a wide range of potentially valuable meso-aryl-
1,3,5,7-tetramethyl-BODIPY derivatives.
2
of different oxidants to establish the reaction conditions in the
diiodination at the 2,6-positions (Scheme 2, Table 1). The
reaction of 1a with I
was performed in CH
give only 50% yield (Entry 1, Table 1). Subsequently, the
reactions of 1a with I in the presence of different oxidants or in
2
(2.2 equiv) in the absence of any oxidants
3
CN at room temperature for 10 hours to
2
different solvents were screened respectively. The only efficient
oxidant we tested was phenyliodine (III) diactate due to IOAc
Acknowledgments
existence which was generated from the combination of I
PhI(OAc) in situ as the effective iodination reagent. The
solvents affect the yields of the diiodination product remarkably.
Moreover, the amount of I can also affect the yield of the
2
with
2
We thank the Analysis and Testing Center of the School of
Chemical Engineering in Nanjing University of Science and
Technology for the NMR experiments.
2
product 2a slightly (Table 1, entry 11). Based on the screening
results, the optimized diiodination condition was obtained:
Supplementary Material
reaction of 1a with 2.2 equivalents of I
PhI(OAc) in acetonitrile was carried out at room temperature for
0 hours to afford 2a in 93 % isolated yield (Entry 11, Table 1).
2
and 2.0 equivalents of
2
1
Supplementary data (experimental procedures and spectral
data) associated with this article can be found, in the online
version, at doi:
With the optimized reaction results in hand, the scope and
generality of the diiodination of BODIPYs by using IOAc as the
iodination reagent were examined with a series of meso-aryl-
1
,3,5,7-tetramethyl-BODIPYs under the best reaction condition,
14
and the full results are summarized in Table 2. As depicted in
Table 2, all reactions of different substrates with either electron-
withdrawing groups or the electron-donating groups in its meso
aromatic units proceeded smoothly to afford the products 2 in
high to excellent yields.
References and notes
1.
(a) Golovkova, T. A.; Kozlov, D. V.; Neckers, D. C. J. Org.
Chem. 2005, 70, 5545. (b) Trieflinger, C.; Rurack, K.; Daub, J.
Angew. Chem. Int. Ed. 2005, 44, 2288. (c) Deniz, E.; Sortino, S.;
Raymo, F-i. M. J. Phys. Chem. Lett. 2010, 1, 1690. (e)
Pochorovski, I.; Breiten, B.; Schweizer, W. B.; Diederich F. Chem.
Eur. J. 2010, 16, 12590.
Inspired by the above interesting results, we next focus the
second goal of our work on investigating the monoiodination of
2
3
.
.
(a) Haugland, R. P. The Handbook-A guide to fluorescent probes
and labeling technologies, 10th ed.; Invitrogen Corp., 2005. (b)
Ehrenschwender, T.; Wagenknecht, H-A. J. Org. Chem. 2011, 76,
2301. (c) Wang, D.; Fan, J.; Gao, X.; Wang, B.; Sun, S.; Peng, X.
J. Org. Chem. 2009, 74, 7675. (d) Rayo, J.; Amara, N.; Krief, P.;
Meijler, M. M. J. Am. Chem. Soc. 2011, 133, 7469.
1
,3,5,7-tetramethyl-BODIPYs (Scheme 3). Initially, as an
example, the monoiodination of BODIPY 1i under the similar
reaction condition was carried out. Based on the knowledge that
two equivalents of IOAc generated from the combination of one
equivalent of I
equivalent of I
2
with one equivalent of PhI(OAc)
and 0.5 equivalent of PhI(OAc)
2
in situ, then 0.5
were used in this
(a) Coskun, A.; Akkaya, E. U. J. Am. Chem. Soc. 2005, 127,
2
2
1
0464. (b) Rurack, K.; Kollmannsberger, M.; Resch-Genger, U.;
monoiodination. Unfortunately, the desired monoiodination
product 3i was obtained only in 40% yield together with the
diiodination product 2i as the side product. In an attempt to
obtain the best result, we tried to investigate the effects of
Daub, J. J. Am. Chem. Soc. 2000, 122, 968. (c) Coskun, A.;
Akkaya, E. U. J. Am. Chem. Soc. 2006, 128, 14474. (d) Zeng, L.;
Miller, E. W.; Pralle, A.; Isacoff, E. Y.; Chang, C. J. J. Am. Chem.
Soc. 2006, 128, 10. (e) Coskun, A.; Deniz, E.; Akkaya, E. U. Org.
Lett. 2005, 7, 5187. (f) Saki, N.; Dinc, T.; Akkaya, E. U.
Tetrahedron 2006, 62, 2721. (g). Ekmekci, Z.; Yilmaz, M. D.;
Akkaya, E. U. Org. Lett. 2008, 10, 461. (h) Bozdemir, O. A.;
Guliyev, R.; Buyukcakir, O.; Selcuk, S.; Kolemen, S.; Gulseren,
G.; Nalbantoglu, T.; Boyaci, H.; Akkaya, E. U. J. Am. Chem. Soc.
different solvents, reaction temperature, the amounts of I
PhI(OAc) , and various bases such as Na CO , K CO , KOAc,
NaHCO , and NEt as the additive (see Table S1, Supplementary
2
and
2
2
3
2
3
3
3
data). After varying the reaction conditions, it was found that the
best choice for the monoiodination is: reaction of 1i with 0.48
2
010, 132, 8029; (i) Bozdemir, O. A.; Sozmen, F.; Buyukcakir, O.;
Guliyev, R.; Cakmak, Y.; Akkaya, E. U. Org. Lett. 2010, 12, 1400.
(a) Umezawa, K.; Nakamura, Y.; Makino, H.; Citterio, D.; Suzuki,
K. J. Am. Chem. Soc. 2008, 130, 1550. (b) Loudet, A.; Burgess, K.
Chem. Rev. 2007, 107, 4891. (c) Hayashi, Y.; Obata, N.; Tamaru,
M.; Yamaguchi, S.; Matsuo, Y.; Saeki, A.; Seki, S.; Kureishi, Y.;
Saito, S.; Yamaguchi, S.; Shinokubo, H. Org. Lett. 2012, 14, 866.
2 2 3
equivalent of I and 0.48 equivalent of PhI(OAc) in CH CN-
4
.
EtOH (1:1, v:v) was carried out at -25 for 12 hours to afford 3i
15
in 74 % isolated yield. To extend the substrate scope and
versatility of the monoiodination, a variety of different substrates
were further explored under the optimal reaction condition. As
the results summarized in Table 3, the expected products 3 could
be obtained in good isolated yields for both electron-rich and
electron-deficient aromatic groups on the meso-position of
BODIPY derivatives. For the di- and monoiodination of
BODIPYs, the position of the substitutes did not affect the yield
of the corresponding product (Entries 7, 9 and 11, Table 2 and 3).
In all cases, the di- and monoiodination products 2 and 3 were
(
2
d) Ulrich, G.; Ziessel, R.; Harriman, A. Angew. Chem., Int. Ed.
008, 47, 1184. (e) Ziessel, R.; Ulrich, G.; Harriman, A. New J.
Chem. 2007, 31, 496. (f) Buyukcakir, O.; Bozdemir, O. A.;
Kolemen, S.; Erbas, S.; Akkaya, E. U. Org. Lett. 2009, 11, 4644.
(
g) Jiao, C.; Huang, K-W.; Wu, J. Org. Lett. 2011, 13, 632 (h)
Kowada, T.; Yamaguchi, S.; Ohe, K. Org. Lett. 2010, 12, 296. (i)
Thivierge, C.; Loudet, A.; Burgess, K. Macromolecules 2011, 44,
4
012.
5.
(a) Bozdemir, Ö. A.; Büyükcakir, O.; Akkaya, E. U. Chem. Eur. J.
2009, 15, 3830. (b) V Donuru, R.; Vegesna, G. K.; Velayudham,
S.; Green, S.; Liu, H. Chem. Mater. 2009, 21, 2130. (c) Wu, Y.; M,
X.; Jiao, J.; Cheng, Y.; Zhu, C. Synlett 2012, 23, 778.
1
13
characterized by H NMR, C NMR, and HRMS respectively
see Supplementary data).
(
6
.
(a) Li, F.; Yang, S. I.; Ciringh, Y. Z.; Seth, J.; Martin, C. H.; Singh,
D. L.; Kim, D.; Birge, R. R.; Bocian, D. F.; Holten, D.; Lindsey, J.
L. J. Am. Chem. Soc. 1998, 120, 10001. (b) Yilmaz, M. D.;
Bozdemir, O. A.; Akkaya, E. U. Org. Lett. 2006, 8, 2871. (c)
Zhang, X.; Xiao, Y.; Qian, X. Org. Lett. 2008, 10, 29.
3
. Conclusion
In conclusion, we have developed a practical and efficient
approach to the iodination of 1,3,5,7-tetramethyl-BODIPYs.

3
7
8
9
.
.
.
(a) Atilgan, S.; Ekmekci, Z.; Dogan, A. L.; Guc, D.; Akkaya, E. U.
Chem. Commun. 2006, 4398. (b) Ozlem, S.; Akkaya, E. U. J. Am.
Chem. Soc. 2009, 131, 48. (c) Lim, S. H.; Thivierge, C.; Nowak-
Sliwinska, P.; Han, J.; Bergh, H. van den; Wagniéres, G.; Burgess,
K.; Lee, H. B. J. Med. Chem. 2010, 53, 2865.
(a) Yuan, M.; Zhou, W.; Liu, X.; Zhu, M.; Li, J.; Yin, X.; Zheng,
H.; Zuo, Z.; Ouyang, C.; Liu, H.; Li, Y.; Zhu, D. J. Org. Chem.
2
008, 73, 5008. (b) Bozdemir,O.A.; Guliyev,R.; Buyukcakir, O.;
Selcuk, S.;Kolemen, S.;Gulseren, G.;Nalbantoglu, T.; Boyaci,
H.;Akkaya, E. U. J. Am. Chem. Soc. 2010, 132, 8029.
(a) Hattori, S.; Ohkubo, K.; Urano, Y.; Sunahara, H.; Nagano, T.;
Wada, Y.; Tkachenko, T. V.; Lemmetyinen, H.; Fukuzumi, S. J.
Phys. Chem. B 2005, 109, 15368. (b) Erten-Ela, S.; Yilmaz, M. D.;
Icli, B.; Dede, Y.; Icli, S.; Akkaya, E. U. Org. Lett. 2008, 10, 3299.
(
c) Ueno, Y.; Jose, J.; Loudet, A.; Pérez-Bolívar, C.; Anzenbacher,
Jr., P.; Burgess, K. J. Am. Chem. Soc. 2011, 133, 51. (d) Warnan,
J.; Buchet, F.; Pellegrin, Y.; Blart, E.; Odobel, F. Org. Lett. 2011,
1
3, 3944. (e) Wang, J-B.; Fang, X-Q.; Pan, X.; Dai, S-Y.; Song,
Q-H. Chem. Asian J. 2012, 7, 696.
1
1
0. (a) Sameiro, M.; Gonçalves, T. Chem. Rev. 2009, 109, 190. (b)
Kuimova, M. K.; Yahioglu, G.; Levitt, J. A.; Suhling, K. J. Am.
Chem .Soc. 2008, 130, 6672.
1. (a) Yogo, T.; Urano, Y.; Ishitsuka, Y.; Maniwa, F.; Nagano, T. J.
Am. Chem. Soc. 2005, 127, 12162. (b) Adarsh, N.; Avirah, R. R.;
Ramaiah, D. Org. Lett., 2010, 12, 5720. (c) Pang, W.; Zhang, X-
F.; Zhou, J.; Yu, C.; Hao, E.; Jiao, L. Chem. Commun. 2012, 48,
5
437.
1
2. (a) Wu, W.; Zhao, J.; Guo, H.; Sun, J.; Ji, S.; Wang, Z. Chem. Eur.
J. 2012, 18, 1961. (b) Fu, G-L.; Pan, H.; Zhao, Y-H.; Zhao C-H.
Org. Biomol. Chem. 2011, 9, 8141. (c) Chen, Y.; Zhao, J.; Guo, H.;
Xie, L. J. Org. Chem. 2012, 77, 2192. (d) Meng, G.; Velayudham,
S.; Smith, A.; Luck, R.; Liu, H. Macromolecules 2009, 42, 1995.
(
e) Rihn, S.; Erdem, M.; De Nicola, A.; Retailleau, P.; Ziessel, R.
Org. Lett. 2011, 13, 1916. (f) Bonardi, L.; Ulrich, G.; Ziessel, R.
Org. Lett. 2008, 10, 2183. (g) Cakmak, Y.; Akkaya, E. U. Org.
Lett. 2009, 11, 85. (h) Zhang, D.; Wen, Y.; Xiao, Y.; Yu, Gui.; Liu,
Y.; Qian, X. Chem. Commun. 2008, 4777. (i) Lu, H.; Wang, Q.;
Gai, L.; Li, Z.; Deng, Y.; Xiao, X.; Lai, G.; Shen, Z. Chem. Eur. J.
2
012, 18, 7852. (j) Wu, W.; Guo, H.; Wu, W.; Ji, S.; Zhao, J. J.
Org. Chem. 2011, 76, 7056. (k) Shao, J.; Sun, H.; Guo, H.; Ji, S.;
Zhao, J.; Wu, W.; Yuan, X.; Zhang, C.; James, T. D. Chem. Sci.
2
012, 3, 1049. (l) Popere, B. C.; Della Pelle, A. M.;
Thayumanavan, S. Macromolecules 2011, 44, 4767. (m) Sun, H.;
Dong, X.; Liu, S.; Zhao, Q.; Mou, X.; Yang, X. Y.; Huang, W. J.
Phys. Chem. C 2011, 115, 19947.
1
1
3. (a) Wei, H-L.; Piou, T.; Dufour, J.; Neuville, L.; Zhu, J. Org. Lett.
2
011, 13, 2244. (b) Mei, T-S.; Giri, R.; Maugel, N.; Yu, J-Q.
Angew. Chem. Int. Ed. 2008, 47, 5215. (c) Gottam, H.; Vinod, T.
K. J. Org. Chem. 2011, 76, 974. (d) Fan, R.; Li, W.; Pu, D.; Zhang,
L. Org. Lett. 2009, 11, 1425. (e) Dudnik, A. S.; Chernyak, N.;
Huang, C.; Gevorgyan, V. Angew. Chem., Int. Ed. 2010, 49, 8729.
(
f) Huang, C.; Chernyak, N.; Dudnik, A. S.; Gevorgyan, V. Adv.
Synth. Catal. 2011, 353, 1285.
4. General procedure for 2a-2l: A mixture of 1 (0.2 mmol) and I
2
(
2
0.44 mmol) together with PhI(OAc) (0.40 mmol) in 50 ml
round-bottomed flask containing CH CN (20 ml) was stirred at
3
room temperature for 10 hours based on the TLC analysis. The
residue obtained after the removal of the solvent by rotary
evaporation was extracted with EtOAc and washed with saturated
solution of aqueous Na
then dried over anhydrous Na
crude product was further purified using column chromatography
EtOAc: Petroleum ether) to afford 2.
5. General procedure for 3a-3l: To a solution of I
PhI(OAc) (0.096 mmol) in EtOH (10 ml) was added a solution of
(0.2 mmol) and NaHCO (0.3 mmol) in CH CN (10 ml) slowly.
2
S
2
O
3
(3×20 mL), and water (3×30 ml),
2
SO and evaporated in vacuo. The
4
(
1
2
(0.096 mmol) and
2
1
3
3
The mixture was stirred at -25 for 12 hours based on the TLC
analysis. The residue obtained after the removal of the solvent by
rotary evaporation was extracted with EtOAc and washed
saturated solution of aqueous Na
2
S
2
O
3
(3×20 mL), and water
SO and evaporated in
(
3×30 ml), then dried over anhydrous Na
2
4
vacuo. The crude product was further purified using column
chromatography (EtOAc: Petroleum ether) to afford 3.

R
R
PhI(OAc)2/I2
X
I
N
N
N
N
B
B
F
F
F
F
2
3
X = I
1
H
Scheme 1. Iodination of 1
R
R
PhI(OAc) (2.0eq.)/I (2.2eq.)
2
2
I
I
N
N
CH3CN, r.t
N
N
B
B
F
F
F
F
1
2
Scheme 2. Diiodination of 1
R
R
PhI(OAc) (0.48eq.)/I (0.48eq.)
2
2
o
I
N
N
NaHCO3(1.5eq.), -25 C
CH3CN-EtOH(1:1, v:v)
N
N
B
B
F
F
F
F
1
3
Scheme 3. Monoiodination of 1

a
Entry
1
R
H
Products 3 and Yield (%)
3a (78)
Yield
2
3
4
5
6
7
8
9
p-CH
3
3b (69)
3c (72)
3d (73)
3e (70)
3f (69)
3g (75)
3h (68)
3i (74)
3j (71)
3k (73)
3l (72)
Entry
I source
Solvent
a
(
%)
1
I
I
I
I
I
2
2
2
2
2
(2.2eq.)
(2.2eq.) /H
(2.2eq.) /CAN (2.0eq.)
(2.2eq.) /K (2.0eq.)
(2.2eq.) /(NH
CH
CH
CH
CH
CH
3
3
3
3
3
CN
CN
CN
CN
CN
50
p-OCH3
m,p-dimethoxyl
p-Cl
2
3
4
5
O
2 2
(2.0eq.)
trace
N.R
trace
trace
2 2 8
S O
o-Cl
4 2 2 8
) S O
(
2.0eq.)
o-CF
3
6
7
8
9
1
1
I
2
I
2
I
2
I
2
I
2
(2.2eq.) /PhI(OAc)
2
(2.0eq.)
(2.0eq.) EtOAc
(2.0eq.) CH Cl
(2.0eq.) (CH
(2.0eq.) MeOH
CH CN
HOAc
65
40
30
35
70
93
p-NO
2
(2.2eq.) / PhI(OAc)
(2.2eq.) / PhI(OAc)
(2.2eq.) / PhI(OAc)
(2.2eq.) / PhI(OAc)
2
2
2
2
2
2
p-CF
p-CN
m-CF
3
2 2 2
) Cl
1
1
0
1
0
3
1
I
2
(2.2eq.) / PhI(OAc)
2.0eq.)
(2.0eq.) / PhI(OAc)
2
3
(
12
o-naphthyl
1
2
I
2
2
3
(2.0eq.) CH CN
88
a
Isolated Yield.
a
Isolated Yield.
Table 3 Monoiodination of 1 with PhI(OAc)2/I2
Table 1 Optimization of Diiodination of 1a
a
Entry
1
R
H
Products 2 and Yield (%)
2a (93)
2
3
4
5
6
7
8
9
p-CH
3
2b (85)
2c (92)
2d (91)
2e (94)
2f (90)
2g (95)
2h (87)
2i (96)
2j (92)
2k (97)
2l (95)
p-OCH
3
m,p-dimethoxyl
p-Cl
o-Cl
o-CF
3
p-NO
2
p-CF
p-CN
m-CF
3
1
1
1
0
1
2
3
o-naphthyl
a
Isolated Yield.
Table 2 Diiodination of 1 with PhI(OAc)2/I2