1070-4272/02/7502-0332 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 2, 2002, p. 332. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 2, 2002,
Original Russian Text Copyright + 2002 by Wamhoff, Zlotskii, Saprygina.
Oxidative Dehydrogenation of 4-Arylurazoles
H. Wamhoff, S. S. Zlotskii, and V. A. Saprygina
Kekulé Institut f ur Organische Chemie und Biochemie der Universit at Bonn, Bonn, Germany
Ufa State of University of Petroleum Engineering, Ufa, Bashkortostan, Russia
Reaktiv Research Institute, Ufa, Bashkortostan, Russia
Received July 9, 2001
Abstract-4-Arylurazoles are selectively oxidized with Fe
O to the corresponding D
Recently there has been growing interest in D
triazoline-3,5-diones, which are extremely active di-
enophiles and are successfully used in syntheses of
fused and polysubstituted heterocycles . Also,
these compounds react with olefins to form the cor-
responding secondary amines [4, 5]. The most ver-
satile and widely used route to D
diones is oxidation of the corresponding urazoles
Along with the use of powerful oxidants, such as
tert-butyl hypochlorite , trichloroacetyl isocyanate
, or nitrogen dioxide , procedures have been
developed for oxidation with N-bromosuccinimide
[9, 10] and halogens :
where R = Ph (a), 4-ClC
In addition to the known procedures, we found that
4-arylurazoles Ia3Ic can be oxidized to 4-aryl-D
triazoline-3,5-diones IIa3IIc with iron(III) nitrate un-
der mild conditions in high yields (65375%). The re-
action occurs in the solid phase, which considerably
simplifies the isolation and purification of the target
diones IIa3IIc. A similar procedure has been used
previously to prepare substituted semicarbazides .
A mixture of triazolidinedione Ia3Ic with Fe
O (molar ratio 1 : 2) was ground in an agate mor-
tar for 538 min. The mixture was transferred into dry
acetone (15 ml per millimole of Ia3Ic), concentrated
HCl was added to pH < 2, and the resulting bright red
liquid was diluted with an equal volume of ice-cold
water. The precipitate was filtered off, washed with
water, and vacuum-dried. Target compounds IIa3IIc
were obtained in 65375% yields; their constants
agreed with published data [9, 10].
The study was performed within the framework
of the Academic Exchange Program of the German
Academy (DAAD), grant A/99/09940.
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