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PIL’O et al.
pack, by the hydrogen bonds O2 H2N3 [O2 N3
2-Acylamino-3,3-dichloroacrylonitriles
Ia Ic
2.906(2), O2 H2 2.05(2), and N3 H2 0.87(2)
;
were prepared as described in [12, 13]. The previously
unknown 3,3-dichloro-2-p-fluorobenzoylaminoacrylo-
nitrile (Id) was prepared like Ia [12].
O2H2N3 167.2(1.7) ], in infinite chains (the mean
value for H O hydrogen bonds like N H O is
2.89
[6]).
2-Aryl-4-cyano-5-hydrazinooxazoles IIa IId.
Hydrazine hydrate, 0.035 mol, was added to a solu-
tion of 0.01 mol of compound Ia Id in 30 ml of
ethanol. The mixture was allowed to stand for 48 h at
20 25 C, the residue was filtered off, washed with
water, dried at 70 80 C, and crystallized from ethanol.
Thus, the structure of substituted 1,3,4-oxadiazoles
VIIa VII is beyond question, but the mechanism of
their formation and the application field of the re-
cyclization II
VII extends the range of known
methods of synthesis of 1,3,4-oxadiazoles [7], deserve
further investigation. Note, however, that attempts to
involve in such transformation 4-cyano-5-hydroxy-2-
methyloxazole obtained in [8] proved unsuccessful.
5-[Acylamino(carbamoyl)methyl]-2-methyl-
1,3,4-oxadiazoles VIIa VIId. A solution of 0.005
mol of compound IIa IId in 10 ml of glacial acetic
acid was refluxed for 8 h and left to stand for 12 h at
20 25 C. The solvent was removed in a vacuum, the
residue was treated with water, the precipitate was
filtered off, dried at 70 80 C, and purified by crystal-
lization.
EXPERIMENTAL
The IR spectra were recorded on a Specord M-80
1
spectrometer in KBr pellets. The H and 13C NMR
spectra were obtained on a Varian VXR-300 spectro-
meter in (CD3)2SO or CDCl3, standard TMS.
The X-ray diffraction analysis of a single crystal
(0.11 0.22 0.38 mm) of compound VIIc was per-
formed at room temperature on an Enraf Nonius
CAD-4 automatic four-circle diffractometer [CuK
2-Aryl-4-cyano-5-[2-p-chloro(methoxy)benzyl-
ydenehydrazino]oxazoles VIIIa, VIIIb, IXa, IXb.
A solution of 0.005 mol of an aromatic aldehyde in 5
ml of ethanol was added to a 0.005 mol of compound
IIa or IIb in 15 ml ethanol under reflux. The mixture
was refluxed for 10 15 min, the precipitate that
formed was filtered off, dried at 70 80 C, and puri-
fied by crystallization.
radiation ( 1.54178 ), /2 1.2,
65 , 0
h
13, 0 8, 20
k
l
20]. The unimt acxell parameters
and orientation matrix were determined with 22 reflec-
tions with 24.4 < < 26.5 . A total of 2753 reflec-
tions were measured, 2394 of which were symmetri-
cally independent (R 0.012). The crystals of com-
pound I are monoclinic, a 11.898(2), b 6.910(1), c
2-Aryl-4-cyano-5-(1-p-toluoylhydrazino)oxazoles
Xa, Xb. Triethylamine and p-toluoyl chloride,
0.005 mol each, were added to a solution of
0.005 mol of compound IIa or IIb in 15 ml of dry
acetonitrile. The mixture was left to stand for 48 h at
20 25 C, the precipitate was filtered off, the filtrate
was vacuum-evaporated, the residue was dried at 70
80 C, and purified by crystallization.
17.183(2)
;
91.13(1) , V 1412.4 3, M 289.27, Z
1
4, dcalc 1.36 g/cm3, 8.32 cm , space group R21/C
(N 14). The structure was solved by the direct method
and subjected to full-matrix least-squares anisotropic
refinement using the CRYSTALS package [9]. In the
refinement, 1800 reflections with I > 3 (I) were used
(243 refined parameters, reflections/parameter 7.4).
All hydrogen atoms (except for H atoms of the dis-
ordered methyl group 13CH3) were revealed objective-
ly by difference synthesis and refined isotropically.
The 13CH3 hydrogens were placed at computed posi-
tions and included in the refinement with fixed posi-
tional and thermal parameters. Absorption was ac-
counted for using azimuthal scanning technique [10].
The refinement was performed by the Chebyshev
weight scheme [11] with the following parameters:
1.65, 1.21, 1.63, 0.36, and 0.47. The final divergence
factors were R 0.038 and RW 0.042; GOF 1.149. The
residual electron density from the Fourier difference
series was 0.14 and 0.18 e/ 3. The principle bond
lengths and bond angles in molecule VIIc are listed
in Table 3, and the coordinates of atoms and their
thermal parameters, in Table 4.
5-[2-(p-Chloro(methoxy)benzylidene)-1-p-toluoyl-
hydrazino]-4-cyano-2-phenyloxazoles XIa, XIb. An
aromatic aldehyde, 0.005 mol, was added to a solution
of 0.005 mol of compound Xa in 15 ml of ethanol,
the mixture was refluxed for 2 h, and left to stand at
20 25 C for 12 h. The precipitate that formed was
filtered off, and compounds XIa, XIb were purified
by crystallization.
ACKNOWLEDGMENTS
The work was supported by INTAS (grant no. 96-
11150) and performed under the general supervision
of G. Reiners (Catholic University of Leuven,
Belgium) to whom the authors express their gratitude.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 2 2001
Pil'o
