EXPERIMENTAL
IR spectra were taken on a UR-20 spectrometer. H NMR spectra were recorded on a Bruker MCL-250
1
(
250 MHz) spectrometer with DMSO-d as internal standard. In the synthesis of compound 2 by the different
6
methods, the identity of the samples obtained was established by a comparison of physical and spectroscopic
properties and also by the absence of a depression of melting point for mixed samples.
Melting points were determined on a Boetius stage.
X-ray Analysis was performed on an Enraf-Nonius CAD-4 automatic, four circle diffractometer.
Crystals of compound 2 are monoclinic, C15
β = 105.02(7)°; V = 1182(2) Å ; Z = 4; dcalc = 1.41 g/cm ; space group P2
H
10
N
2
O
2
. At 20°C a = 14.47(3), b = 5.604(2), c = 15.09(1) Å;
3
3
1
/n. Cell parameters and intensities of
3
076 reflections (of which 2386 had I ≥ 3σ) were measured at 20°C using λCuKα, graphite monochromator,
ω/2θ scanning, with θ ≤ 26.3°. A decrease in the intensity of three control reflections with exposure time was
-1
not observed. An empirical calculation of absorption was carried out (µCu 7.40 cm ). The structure was solved
by a direct method using the SIR program [9] and refined initially in the isotropic and then the anisotropic
approximation. Subsequently, difference array electron density revealed the hydrogen atoms which were refined
in the isotropic approximation in the final least squares cycles. The final difference factor values were:
2
R = 0.048, R
w
= 0.064 for 1795 independent reflections with F ≥ 3σ. All of the calculations were carried out
using the MolEN program package [10] on an AlphaStation 200 computer. The Figures were realized using the
PLATON program [11].
3
-(α-Azidobenzyl)-2-oxo-1,2-dihydroquinoxaline (5). A solution of compound 1 (2.10 g, 8 mmol) in
DMSO (20 ml) was stirred for 6 h at room temperature with NaN
3
(0.78 g, 12 mmol). The latter gradually
dissolved and a precipitate was then formed. The reaction mixture has held at the same temperature for about
1
6 h, poured into water, and the precipitated product 5 was filtered off and washed with water and propan-2-ol
-1
to give 2.11 g (98%); mp 206-208°C (dioxane). IR spectrum (vaseline), ν, cm : 1655 (C=O), 2120 (N
3
),
1
2
H
580-3220 (NH). H NMR spectrum (DMSO-d
6
), δ, ppm, J (Hz): 6.18 (1H, s, CHPh); 7.41-7.52 (7H, m, HBz
,
Ph-7, HPh-8); 7.67 (1H, ddd, J = 7.48, 7.48, 1.27, HPh-6); 7.96 (1H, d, J = 7.75, HPh-5); 12.70 (1H, s, NH).
Found, %: C 65.36; H 3.90; N 25.43. C15
H
11
N
5
O. Calculated, %: C 64.97; H 4.00; N 25.26.
3
-Benzoyl-2-oxo-1,2-dihydroquinoxaline (2). A. A solution of compound 1 (0.50 g, 1.80 mmol) in
DMSO (5 ml) was refluxed for 1 h, cooled, poured into ice, and a solution of sodium carbonate was added. The
precipitated crystals of the product 2 were filtered and washed with water. Yield 0.14 g (30%).
B. A solution of compound 1 (0.50 g, 1.80 mmol) and sodium acetate (0.18 g, 2.0 mmol) in DMSO
(
(
5 ml) was refluxed for 45 min. The reaction mixture was then cooled and poured into water. Yield 0.39 g
84%).
C. A solution of azide 5 (0.30 g, 1.10 mmol) in DMSO (5 ml) was refluxed for 30 min, cooled, poured
into water, and the precipitated crystals of product 2 were filtered off, and washed with water. Yield 0.22 g
(
81%).
D. A solution of azide 5 (1.10 g, 4.0 mmol) in AcOH (10 ml) was refluxed for 30 min, cooled, the
precipitated crystals of product 2 filtered off, and washed with 2-propanol. The filtrate was poured into water
and the precipitated crystals of product 2 were filtered off and washed with water and 2-propanol. Overall yield
0
.9 g (95%).
E. A solution of azide 5 (1.10 g, 4.0 mmol) in 6.1 M HCl (20 ml) was refluxed for 30 min, cooled, and
the precipitated crystals of product 2 were filtered and washed with water, 5% aqueous sodium carbonate, and
again water. Yield 0.97 g (98%).
Parameters for compound 2 and a method for its purification are given in the study [3].
1
509
Mamedov
