Alternative, easy preparation of (diacetoxyiodo)arenes from iodoarenes using potassium peroxodisulfate as the oxidant

Article abstract of DOI:10.1055/s-2005-869962

An easy, safe and effective method for preparing (diacetoxyiodo)arenes [ArI(OAc)₂], from iodoarenes is presented in this paper, using potassium peroxodisulfate as the oxidant. This procedure avoids the use of high temperature and severe reaction conditions. The reaction of the iodoarenes with potassium peroxodisulfate in acetic acid in the presence of concentrated sulfuric acid or trifluoromethane sulfonic acid at room temperature, efficiently generates the corresponding (diacetoxyiodo)arenes in high yield in a short reaction time. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2005-869962

1932
SHORT PAPER
Alternative, Easy Preparation of (Diacetoxyiodo)arenes from Iodoarenes
Using Potassium Peroxodisulfate as the Oxidant
Preparationof
(
Diaceto
d
xyiodo)aren
.
es fromIodo
D
arenes
U
singPota
e
ssium Pero
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xodisul
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fate ar Hossain, Tsugio Kitamura*
Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi,
Saga 840-8502, Japan
Fax +81(952)288548; E-mail: kitamura@cc.saga-u.ac.jp
Received 24 January 2005; revised 15 March 2005
vi. Oxidation of iodoarenes are using sodium percarbon-
Abstract: An easy, safe and effective method for preparing (diacet-
oxyiodo)arenes [ArI(OAc)2], from iodoarenes is presented in this
paper, using potassium peroxodisulfate as the oxidant. This proce-
dure avoids the use of high temperature and severe reaction condi-
tions. The reaction of the iodoarenes with potassium
peroxodisulfate in acetic acid in the presence of concentrated sulfu-
ric acid or trifluoromethane sulfonic acid at room temperature, effi-
ciently generates the corresponding (diacetoxyiodo)arenes in high
yield in a short reaction time.
ate in an anhydrous ternary solvent system (Ac2O–
AcOH–CH2Cl2).13
The standard, and most general, method for the synthesis
of (diacetoxyiodo)arenes (oxidative diacetoxylation of
aryl iodide by warm peracetic acid solution) requires a
very long reaction time (12–16 h), and the utmost care
should be taken to maintain the temperature at exactly
40 °C. Two-step conversion of various aryl iodides to (di-
acetoxyiodo)arenes in the anhydrous chromium(III) ox-
ide, acetic acid, acetic anhydride, concentrated sulfuric
acid liquid system, followed by mixing with an excess of
20% aqueous ammonium acetate solution, gives (diacet-
oxyiodo)arenes in good yields. This procedure is 8–16
times faster and about five times less expensive than the
method of McKillop and Kemp.8 However, this method is
not applicable to iodotoluenes [4-MeC6H4I(OAc)2 was
obtained from 4-MeC6H4I in only 20% yield]. For aryl io-
dides substituted with strong electron withdrawing
groups, the sodium periodate system is not applicable.12 In
the sodium percarbonate method,13 4-iodotoluene and 4-
chloroiodobenzene were unexpectedly oxidized to the
corresponding iodylarenes. Here we wish to report an al-
ternative, easy method for the preparation of (diacetoxy-
iodo)arenes from iodoarenes.
Key words: (diacetoxyiodo)arenas, iodoarenes, potassium peroxo-
disulfate, hypervalent iodine, oxidation
(Diacetoxyiodo)arenes [ArI(OAc)2], and particularly the
parent compound, (diacetoxyiodo)benzene, [PhI(OAc)2],
have been known for a long time.1–5 They are potent, often
chemoselective oxidants, widely used in modern organic
synthesis. They are also used for the facile synthesis of,
for example, iodosylarenes, [bis(trifluoroacetoxy)io-
do]arenes, [hydroxyl(tosyloxy)iodo]arenes (selective oxi-
dants) and aromatic iodonium salts (arylating reagents),
etc.2–6 Several methods are available for the preparation of
(diacetoxyiodo)arenes. Historically, the first member, (di-
acetoxyiodo)benzene was synthesized by Willgerodt in
1892, by dissolving iodosylbenzene in hot acetic acid.7
The methods used so far are generally as follows:
In our laboratory, we found a quick and efficient method
for preparing (diacetoxyiodo)arenes in high yield in a
short reaction time from the corresponding iodoarenes in
acetic acid, using commercial potassium peroxodisulfate
as the oxidant. The results are given in Table 1. Addition
of concentrated sulfuric acid or trimethane sulfonic acid is
essential to generate (diacetoxyiodo)arenes. Potassium
peroxodisulfate is used as a strong oxidizing agent in
many applications. It has the particular advantages of be-
ing almost non-hygroscopic, as well as being safe and
easy to handle. The oxidation of iodoarenes to (diacetoxy-
iodo)arenes can be easily scaled up; given the advantages
of potassium peroxodisulfate outlined above, together
with the complete absence of effluent or by-product prob-
lems. The essence of our novel method is described in
Scheme 1.
i. Dissolution of iodosylarenes in glacial acetic acid;
ii. Oxidiation of iodoarenes in warm glacial acetic acid by
either peracetic acid,5 sodium perborate tetrahydrate,8
chromium(VI)oxide,9 or electrolytically;3,4
iii The exchange of chloride with acetoxy groups on
(dichloroiodo)arenes using silver, lead(II) or sodium ace-
tate, or by dissolving the substrate in acetic acid in the
presence of mercury(II) oxide in chlorinated solvents;10
iv. The conversion of iodoarenes to (diacetoxyiodo)arenes
by a two-step reaction – reaction with thionyl chloride to
yield dichloroiodoarenes followed by treatment with
aqueous acetic acid in pyridine;11
v. Refluxing iodoarenes for two hours in a solution of so-
dium periodate, acetic acid, acetic anhydride, and sodium
acetate;12
The oxidative reactions shown in Schemes 1 and 2 were
carried out at room temperature (25 °C), in a mixture of
acetic acid and concentrated sulfuric acid or trifluo-
romethane sulfonic acid. The presence of Potassium per-
oxodisulfate in the reaction mixture was indispensable
SYNTHESIS 2005, No. 12, pp 1932–1934
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Advanced online publication: 24.06.2005
DOI: 10.1055/s-2005-869962; Art ID: F01805SS
© Georg Thieme Verlag Stuttgart · New York

SHORT PAPER
Preparation of (Diacetoxyiodo)arenes from Iodoarenes Using Potassium Peroxodisulfate
1933
room temperature. We believe that the present method
will be widely used because of its simplicity and conve-
nience.
Melting points were determined with a Yanaco micro-melting point
apparatus and are uncorrected. 1H NMR and 13C NMR spectra were
recorded on a JEOL JNM-AL300 spectrometer and the chemical
shifts are expressed in parts per million downfield from tetrameth-
ylsilane.
Scheme 1
(Diacetoxyiodo)arenes from Iodoarenes; General Procedure
K2S2O8 (4 mmol) was slowly added portionwise over 10 min to a
stirred solution of an iodoarene (1 mmol) in AcOH (5 mL) with
concd H2SO4 (4 mmol) or CF3SO3H (6 mmol) at r.t. (25 °C), and the
mixture was stirred at r.t. until TLC analysis indicated completion
of the reaction. In the case of 1,4-diiodobenzene, CH2Cl2 (3 mL)
was added (this ensured the complete dissolution of 1,4-diiodoben-
zene). The solution was then concentrated to half its volume by
evaporation of AcOH under reduced pressure, and H2O (10 mL)
was added. The resulting precipitate was collected by filtration,
washed with H2O (10 mL), and dried in air. A second crop of prod-
uct was obtained by extraction of the filtrate with CH2Cl2 (3 × 10
mL) and the combined extracts were dried over anhyd Na2SO4; after
filtration the solution was concentrated under reduced pressure. The
combined crude products were purified by recrystallization from
AcOH–hexane.
Scheme 2
Table 1 Preparation of (Diacetoxyiodo)arenes from Iodoarenesa
Entry Iodoarenes
Additives (mmol) Time (h) Yield (%)
1
2
3
4
5
6
7
8
C6H5I
H2SO4 (4)
H2SO4 (4)
H2SO4 (4)
CF3SO3H(6)
CF3SO3H(6)
H2SO4 (4)
2
2
2
4
4
4
6
4
95.7
75.2
74.4
77.9
72.9
85.4
65.3
70.7
4-MeC6H4-I
4-ClC6H4-I
3-CF3C6H4-I
3-NO2C6H4-I
1-IC10H7
In the case of 1-iodo-4-nitrobenzene, CF3SO3H (12 mmol) was used
as a promoter and 1,2-dichloroethane (5 mL) was added to dissolve
the substrate.
1,4-I2C6H4
4-FC6H4-I
CF3SO3H(6)b
H2SO4 (4)
(Diacetoxyiodo)benzene
Yield: 0.304 g (95.7%); mp 162–163 °C (lit.14 161.1–162.2 °C).
1H NMR (300 MHz, CDCl3): d = 2.01 (s, 6 H, MeCO2), 7.47–7.53
(m, 2 H, ArH), 7.58–7.64 (m, 1 H, ArH), 8.07–8.12 (m, 2 H, ArH).
13C NMR (75 MHz, CDCl3): d = 176.19, 134.77, 131.58, 130.79,
121.36, 20.18.
a The reaction of an iodoarene (1 mmol) was carried out in AcOH (5
mL) in the presence of K2S2O8 (4 mmol) at 25 °C.
b CH2Cl2 (3 mL) was added.
because without its addition the oxidation reactions did
not proceed. When potassium peroxodisulfate was re-
placed with sodium peroxodisulfate, the final yields of
(diacetoxyiodo)arenes were lowered by about 11–16%.
1-(Diacetoxyiodo)-4-methylbenzene
Yield: 0.250 g (75.2%); mp 106–108 °C (lit.14 106–110 °C).
1H NMR (300 MHz, CDCl3): d = 2.00 (s, 6 H, MeCO2), 2.44 (s, 3
H, Me), 7.29 (d, J = 8.6 Hz, 2 H, ArH) 7.97 (d, J = 8.6 Hz, 2 H,
Iodoarenes bearing strong electron-withdrawing groups ArH).
13C NMR (75 MHz, CDCl3): d = 176.19, 142.50, 134.82, 131.58,
such as trifluoromethyl and nitro at the meta position also
gave (diacetoxyiodo)arenes in good yields, but the reac-
tion of 1-iodo-4-nitrobenzene and 1-iodo-3,5-bis(trifluo-
romethyl)benzene resulted in low yields (18–20%) of
(diacetoxyiodo)arenes due to their decreased reactivity.
This method was not applicable to iodoarenes with strong
election-donating groups. For example, iodoanisoles were
118.14, 21.37, 20.21.
4-Chloro-1-(diacetoxyiodo)benzene
Yield: 0.265 g (74.4%); mp 110–112 °C (lit.14 109.8–113.2 °C).
1H NMR (300 MHz, CDCl3): d = 2.01 (s, 6 H, MeCO2), 7.46 (d,
J = 8.6 Hz, 2 H, ArH), 8.01 (d, J = 8.6 Hz, 2 H, ArH).
quickly oxidized in the reaction mixtures, but the reaction 13C NMR (75 MHz, CDCl3): d = 176.30, 138.27, 136.22, 131.07,
118.68, 20.18.
resulted in the decomposition and the formation of tarry
products. This method was not applicable to trisubstituted
iodoarenes due to the steric effect of the multiple substit-
Yield: 0.305 g (77.9%); mp 146–147 °C.
uents.
1-(Diacetoxyiodo)-3-(trifluoromethyl)benzene8
1H NMR (300 MHz, CDCl3): d = 2.03 (s, 6 H, MeCO2), 7.65 (t, J =
7.9 Hz, 1 H, ArH), 7.85 (d, J = 7.9 Hz, 1 H, ArH), 8.28 (d, J = 7.9
Hz, 1 H, ArH), 8.33 (s, 1 H, ArH).
13C NMR (75 MHz, CDCl3): d = 176.54, 138.10, 132.87 (q,
JCF = 33.4 Hz, CCF3), 131.67 (q, JCF = 3.7 Hz, CCCF3), 131.21,
128.39 (q, JCF = 3.7 Hz, CCCF3), 122.72 (q, JCF = 272.8 Hz, CF3),
120.90, 20.18.
We have developed a novel preparative procedure, which
is easy, quick, cheap, and possibly environmentally be-
nign. The new method gives (diacetoxyiodo)arenes in
high yields by the reaction of iodoarenes with potassium
peroxodisulfate in acetic acid in the presence of concen-
trated sulfuric acid or trifluoromethane sulfonic acid at
Synthesis 2005, No. 12, 1932–1934 © Thieme Stuttgart · New York

1934
M. D. Hossain, T. Kitamura
SHORT PAPER
1-(Diacetoxyiodo)-3-nitrobenzene
References
Yield: 0.270 g (72.9%); mp 150–152 °C (lit.14 151–154.2 °C).
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mehrwertigem Jod; Enke Verlag: Stuttgart, 1914.
1H NMR (300 MHz, CDCl3): d = 2.04 (s, 6 H, MeCO2), 7.72 (t,
J = 8.1 Hz, 1 H, ArH), 8.39 (d, J = 8.1 Hz, 1 H, ArH), 8.44 (d, J =
8.1 Hz, 1 H, ArH), 8.94 (s, 1 H, ArH).
13C NMR (75 MHz, CDCl3): d = 176.67, 148.47, 140.35, 131.48,
129.94, 126.24, 120.46, 20.16.
(2) Reviews on (diacetoxyiodo)arenes: (a) Varvoglis, A. Chem.
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Iodine; VCH: Weinheim, 1992.
1-(Diacetoxyiodo)naphthalene8
Yield: 0.309 g (85.4%); mp 174–175 °C.
1H NMR (300 MHz, CDCl3): d = 1.92 (s, 6 H, MeCO2), 7.51 (t,
J = 7.8 Hz, 1 H, ArH), 7.62 (t, J = 7.4 Hz, 1 H, ArH), 7.71 (t, J = 7.4
Hz, 1 H, ArH), 7.89 (d, J = 7.8 Hz, 1 H, ArH), 8.09 (d, J = 8.1 Hz,
1 H, ArH), 8.10 (d, J = 8.1 Hz, 1 H, ArH), 8.49 (d, J = 7.2 Hz, 1 H,
ArH).
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(5) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic Press: San Diego, 1997.
13C NMR (75 MHz, CDCl3): d = 176.49, 137.01, 134.33, 133.46,
131.21, 129.54, 129.20, 129.07, 127.60, 126.54, 125.27, 20.16.
(6) For recent reviews on organohypervalent iodine compounds
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29, 409. (b) Varvoglis, A. Tetrahedron 1997, 53, 1179.
(c) Muraki, T.; Togo, H.; Yokoyama, M. Rev. Heteroat.
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G.; Yokoyama, M. Yuki Gosei Kagaku Kyokaishi 1997, 55,
90; Chem. Abstr. 1997, 126, 156952. (e) Moriarty, R. M.;
Prakash, O. Adv. Heterocycl. Chem. 1998, 69, 1.
1,4-Bis(diacetoxyiodo)benzene
Yield: 0.290 g (65.3%); mp 226–228 °C (lit.15 220–223 °C).
1H NMR (CDCl3): d = 1.96 (s, 12 H, MeCO2), 8.23 (s, 4 H, ArH).
1-(Diacetoxyiodo)-4-fluorobenzene
Yield: 0.240 g (70.7%); mp 176.5–177.5 °C (lit.14 177.0–179.8 °C).
(f) Kirschning, A. Eur. J. Org. Chem. 1998, 2267.
(g) Zhdankin, V. V.; Stang, P. J. Tetrahedron 1998, 54,
10927. (h) Varvoglis, A.; Spyroudis, S. Synlett 1998, 221.
(i) Ochiai, M. Kikan Kagaku Sosetsu 1998, 34, 181; Chem.
Abstr. 1998, 129, 216196. (j) Ochiai, M. Farumashia 1999,
35, 140; Chem. Abstr. 1999, 130, 153211. (k) Kita, Y.; Egi,
M.; Takada, T.; Toma, H. Synthesis 1999, 885. (l) Wirth,
T.; Hirt, V. H. Synthesis 1999, 1271. (m) Muller, U. Trends
Photochem. Photobiol. 1999, 5, 117. (n) Chemistry of
Hypervalent Compounds; Akiba, K., Ed.; Wiley-VCH: New
York, 1999, Chap. 11, see also Chap. 12. (o) Grushin, V. V.
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Y. Yuki Gosei Kagaku Kyokaishi 2000, 58, 1048; Chem.
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1H NMR (300 MHz, CDCl3): d = 2.01 (s, 6 H, MeCO2), 7.15–7.21
(m, 2 H, ArH), 8.07–8.13 (m, 2 H, ArH)
13C NMR (75 MHz, CDCl3): d = 176.35, 164.17 (d, JCF = 253.7 Hz,
CF), 137.45 (d, JCF = 8.7 Hz, CCCF), 118.41 (d, JCF = 23.0 Hz,
CCF), 115.39 (d, JCF = 3.7 Hz, CCCCF), 20.18.
1-(Diacetoxyiodo)-4-nitrobenzene9
Yield: 0.073 g (20.0%); mp 104–105 °C
1H NMR (300 MHz, CD3OD): d = 1.96 (s, 6 H, MeCO2), 8.31 (d,
J = 8.8 Hz, 2 H, ArH), 8.38 (d, J = 8.8 Hz, 2 H, ArH).
1-(Diacetoxyiodo)-3,5-bis(trifluoromethyl)benzene16
Yield: 0.083 g (18.0%); mp 108–110 °C.
1H NMR (300 MHz, CDCl3): d = 2.05 (s, 6 H, MeCO2), 8.07 (s, 1
H, ArH), 8.50 (s, 2 H, ArH).
(Diacetoxyiodo)benzene; Large-Scale
K2S2O8 (100 mmol) was slowly added portion-wise over 20 min to
a stirred solution of an iodobenzene (5.10 g, 25 mmol) in AcOH
(125 mL) with concd H2SO4 (100 mmol) at r.t. (25 °C), and the mix-
ture was stirred at r.t. for 4 h. The solution was then concentrated to
half its volume by evaporation of AcOH under reduced pressure,
and H2O (100 mL) was added. The precipitate formed was collected
by filtration, washed with H2O (200 mL), and dried in air. A second
crop of product was obtained by extraction of the filtrate with
CH2Cl2 (3 × 25 mL); the combined extracts were dried over anhyd
Na2SO4, filtered, and concentrated under reduced pressure. The
combined crude products were purified by recrystallization from
AcOH–hexane; yield: 7.15 g (88.7%).
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Synthesis 2005, No. 12, 1932–1934 © Thieme Stuttgart · New York