Reactions of phenyliodosobis-(trifluoroacetate) with derivatives of imidazole

Full text of DOI:10.1007/s10593-007-0169-8

Chemistry of Heterocyclic Compounds, Vol. 43, No. 8, 2007
LETTERS TO THE EDITOR
REACTIONS OF PHENYLIODOSOBIS-
(TRIFLUOROACETATE) WITH DERIVATIVES
OF IMIDAZOLE
E. A. Veretennikov and A. E. Gavrilov
Keywords: imidazole, polyvalent iodine.
The reaction of phenyliodosobis(trifluoroacetate) (FITA) (1) with nucleophiles has been studied with the
objective of preparing stable phenyl derivatives containing polyvalent iodine (I3+). It has been shown that
compound 1 reacts with imidazole 2 in acetonitrile at room temperature to produce 3, the product of
monosubstitution at the iodine atom.
The structure of compound 3 was confirmed by the presence of the characteristic carbonyl group signal
at 1700 cm-1 in the IR spectrum and iodometric titration to give a molecular mass of 386 for the substance. This
corresponds, with negligible error, to the calculated molecular mass of compound 3, 384.093.
F3C
F3C
O
O
O
O
O
HN
N
I
I
+
N
N
O
MeCN
CF3
1
3
2
When the reaction was carried out with 2-methylimidazole (4), a compound with a similar basicity to
imidazole [1], the formation of a black precipitate of unknown structure was observed which gave a
characteristic reaction of polyvalent iodine with starch. This may indicate indirectly the formation of products of
nucleophilic substitution, similar in structure to compound 3.
It is possible that this course of the reaction is explained by the susceptibility of compound 4 to
oxidation with compound 1 as the oxidant [2].
1H NMR spectra were recorded in D2O with H2O as standard on a Bruker AM-500 (500 MHz)
instrument.
__________________________________________________________________________________________
St. Petersburg State Technological Institute (Technological University), St. Petersburg 190013, Russia;
e-mail: toever@yandex.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.8, 1273-1274, August,
2007. Original article submitted November 6, 2006.
0009-3122/07/4308-1081©2007 Springer Science+Business Media, Inc.
1081

1-[Phenyl(trifluoroacetoxy)-λ3-iodanyl]-1H-imidazole (3). Phenyliodosobis(trifluoroacetate) (2g,
4.7 mmol) was added with stirring to a solution of imidazole (1.26 g, 1.88 mmol) (previously kept for 24 h over
P2O5 in a vacuum desiccator) in absolute acetonitrile (15 ml). The mixture was kept for 12 h at room
temperature, the precipitate was filtered off and washed with boiling dichloromethane. The compound 3 obtained
1
was dried in a vacuum desiccator over P2O5. Yield 70%; mp – decomposition began above 60°C. H NMR
spectrum, δ, ppm (J, Hz): 7.55 (3H, s, HPh); 7.85 (2H, s, HPh); 7.95 (1H, d, J = 1.4, HIm); 8.05 (1H, d, J = 1.4,
HIm); 8.15 (1H, s, HIm). Mass spectrum, m/z: 384.120 [M+].
REFERENCES
1.
2.
A. R. Katritzky, Physical Methods in the Chemistry of Heterocyclic Compounds [Russian translation],
Khimiya, Moscow (1966), 660 pages.
P. Stang and V. Zhdankin, Chem. Rev., 96, 1123 (1996).
1082