oxidation of iodoarenes in acetic acid,3-5,8-11 and the
reaction of (dichloroiodo)arenes with metal acetates or
acetic acid.12,13
Unexpected, Drastic Effect of Triflic Acid
on Oxidative Diacetoxylation of Iodoarenes
by Sodium Perborate. A Facile and
Efficient One-Pot Synthesis of
The standard and most general method for the syn-
thesis of ArI(OAc)2 is the oxidative diacetoxylation of ArI
by warm peracetic acid solution. However, it requires a
very prolonged reaction (12-16 h) and the utmost care
to maintain the exact temperature, 40 °C. Two-step
conversion of various ArI to ArI(OAc)2 in the anhydrous
CrO3/AcOH/Ac2O/concentrated H2SO4 liquid system, fol-
lowed by mixing with excess 20% aqueous ammonium
acetate solution, is 8-16 times faster and ca. 5 times less
expensive than the method of McKillop and Kemp.8
However, this method is hardly applicable for iodotolu-
enes [4-MeC6H4I(OAc)2 was obtained from 4-MeC6H4I in
only 20% yield]. For ArI substituted with strong electron-
withdrawing groups, the sodium periodate system is not
applicable.10 In the sodium percarbonate method,11 4-io-
dotoluene and 4-chloroiodobenzene were unexpectedly
overoxidized to the corresponding iodylarenes. McKillop
and Kemp8 examined the reactions of a variety of
iodoarenes with sodium perborate in acetic acid at 40 °C.
This method is very simple and applicable for many
iodoarenes. After crystallizations, they obtained the
purified products in 71-80% yields; no attempt was made
to optimize yields. However, electron-withdrawing sub-
stituents ortho or para to the iodine inhibit this reaction,
and attempts to oxidize iodobenzene in either propionic
or trifluoroacetic acid were unsuccessful. The starting
material was also recovered from the attempted oxida-
(Diacetoxyiodo)arenes
Md. Delwar Hossain and Tsugio Kitamura*
Department of Chemistry and Applied Chemistry, Faculty of
Science and Engineering, Saga University, Honjo-machi,
Saga 840-8502, Japan
Received May 9, 2005
An easy, safe, and effective method for preparing (diacetoxy-
iodo)arenes from iodoarenes is presented. Addition of tri-
fluoromethanesulfonic acid (triflic acid) as a promoter causes
a drastic increase in the yield of (diacetoxyiodo)arenes in
the reaction of iodoarenes with sodium perborate. The
reaction of the iodoarenes with sodium perborate in acetic
acid in the presence of triflic acid at 40-45 °C efficiently
generates the corresponding (diacetoxyiodo)arenes in high
yields within short time.
(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 have received
a great deal of attention due to low toxicity, ready
availability, easy handling, and reactivity similar to that
of heavy metal reagents and anodic oxidation. 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-
(trifluroacetoxy)iodo]arenes, [hydroxyl(tosyloxy)iodo]]-
arenes (selective oxidants), and aromatic iodonium salts
(arylating reagents), etc.2-6 Several methods are available
for the preparation of (diacetoxyiodo)arenes. Historically,
the first member, (diacetoxyiodo)benzene, was synthe-
sized by Willgerodt in 1892 by dissolving iodosylbenzene
in hot acetic acid.7 The representative methods involve
the reaction of iodosylarenes with acetic acid,7 the direct
(6) Recent reviews on organohypervalent iodine compounds and
their applications in organic synthesis: (a) Kitamura, T.; Fujiwara,
Y. Org. Prep. Proced. Int. 1997, 29, 409-458. (b) Varvoglis, A.
Tetrahedron 1997, 53, 1179-1255. (c) Muraki, T.; Togo, H.; Yokoyama,
M. Rev. Heteroatom Chem. 1997, 17, 213-243. (d) Togo, H.; Hoshina,
Y.; Nogami, G.; Yokoyama, M. Yuki Gosei Kagaku Kyokaishi 1997, 55,
90-98; Chem. Abstr. 1997, 126, 156952. (e) Moriarty, R. M.; Prakash,
O. Adv. Heterocycl. Chem. 1998, 69, 1-87. (f) Kirschning, A. Eur. J.
Org. Chem. 1998, 2267-2274. (g) Zhdankin, V. V.; Stang, P. J.
Tetrahedron 1998, 54, 10927-10966. (h) Varvoglis, A.; Spyroudis, S.
Synlett 1998, 221-232. (i) Ochiai, M. Kikan Kagaku Sosetsu 1998, 34,
181-193; Chem. Abstr. 1998, 129, 216196. (j) Ochiai, M. Farumashia
1999, 35, 140-144; Chem. Abstr. 1999, 130, 153211. (k) Kita, Y.; Egi,
M.; Takada, T.; Toma, H. Synthesis 1999, 885-897. (l) Wirth, T.; Hirt,
V. H. Synthesis 1999, 1271-1287. (m) Chemistry of Hypervalent
Compounds; Akiba, K., Ed.; Wiley-VCH: New York, 1999. (n) Grushin,
V. V. Chem. Soc. Rev. 2000, 29, 315-324. (o) Ochiai, M.; Kitagawa, Y.
Yuki Gosei Kagaku Kyokaishi 2000, 58, 1048-1056; Chem. Abstr. 2000,
133, 362660. (p) Mamaeva, E. A.; Bakibaev, A. A. Izv. Vyssh. Uchebn.
Zaved., Khim. Khim. Tekhnol. 2000, 43, 53-64; Chem. Abstr. 2000,
133, 266754. (q) Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2002, 102,
2523-2584. (r) Thoma, H.; Kita, Y. Adv. Synth. Catal. 2004, 346, 111-
124. (s) Thoma, H.; Kita, Y. Yuki Gosei Kagaku Kyokaishi 2004, 62,
116-127. (t) Hypervalent Iodine Chemistry (Top. Curr. Chem. 224);
Wirth, T., Ed.; Springer-Verlag: Berlin, Heidelberg, 2003. (u) Togo,
H.; Sakuratani, K. Synlett 2002, 1966-1975. (v) Varvoglis, A. Synthesis
1984, 709-726; Moriarty, R. M.; Prakash, O. Acc. Chem. Res. 1986,
19, 244-250. (w) Xia, M. Huaxue Tongbao 2003, 66, 207-209; Chem.
Abstr. 2003, 139, 101070.
(1) Willgerodt, C. Die Organischen Verbindungen mit Mehrwertigem
Jod; Enke Verlag: Stuttgart, 1914.
(2) Reviews on (diacetoxyiodo)arenes: (a) Varvoglis, A. Chem. Soc.
Rev. 1981, 10, 377-407. (b) Merkushev, E. B. Russ. Chem. Rev. (Eng.
Transl.) 1987, 56, 826-845. (c) Kirschning, A. J. Prakt. Chem./Chem.-
Ztg. 1998, 340, 184-186. (d) Pohnert, G. J. Prakt. Chem. 2000, 342,
731-734. (e) Tohma, H. Yakugaku Zasshi 2000, 120, 620-629; Chem.
Abstr. 2000, 133, 222460. (f) Arisawa, M.; Toma, H.; Kita, Y. Yakugaku
Zasshi 2000, 120, 1061-1073; Chem. Abstr. 2001, 134, 29586.
(3) Varvoglis, A. The Organic Chemistry of Polycoordinated Iodine;
VCH: Weinheim, 1992.
(7) Willgerodt, C. Ber. Dtsch. Chem. Ges. 1892, 25, 3494-3502.
(8) McKillop, A.; Kemp, D. Tetrahedron 1989, 45, 3299-3306.
(9) Kazmierczak, P.; Skulski, L. Synthesis 1998, 1721-1723.
(10) Kazmierczak, P.; Skulski, L.; Kraszkiewicz, L. Molecules 2001,
6, 881-891.
(4) Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996, 96, 1123-1178.
(5) (a) Sharefkin, J. G.; Salzman, H. Organic Syntheses; Wiley: New
York, 1973; Collect. Vol. V, pp 660-663. (b) Cao, J.; Yang, N.; Yu, X.
Jingxi Huagong Zhongjianti 2003, 33, 36-37; Chem. Abstr. 2004, 141,
104208. (c) Kaguyama, R. Jpn. Kokai Tokkyo Koho JP 2003238496,
2003; Chem. Abstr. 2003, 139, 197258.
(11) (a) Zielinska, A.; Skulski, L. Molecules 2002, 7, 806-809. (b)
Zielinska, A.; Skulski, L. Molecules 2005, 10, 190-194.
(12) Alcock, N. W.; Waddington, T. D. J. Am. Chem. Soc. 1963,
4103-4109.
(13) Karele, B.; Neilans, O. Latv. PSR Zinat. Akad. Vestis, Kim. Ser.
1970, 5 587-590; Chem. Abstr. 1971, 74, 42033.
10.1021/jo050927n CCC: $30.25 © 2005 American Chemical Society
Published on Web 07/15/2005
6984
J. Org. Chem. 2005, 70, 6984-6986