Transformation of substituted 5-amino-1,3-oxazole-4-carbonitriles into new 3,4,5-triaminopyrazole derivatives

Article abstract of DOI:10.1134/S1070363210010172

Reactions of accessible 5-alkylamino- and 5-arylamino-1,3-oxazole-4- carbonitriles with hydrazine hydrate on heating involved a complex transformation sequence resulting in the formation of 3,4,5-triaminopyrazole derivatives. The structure of the products was confirmed by their cyclocondensation with acetylacetone, leading to 2-alkyl(aryl)amino-3-acylamino- 5,7-dimethylpyrazolo[1,5-a]pyrimidines which were identified by NMR spectroscopy using COSY, NOESY, HMQC, and HMBC techniques.

Full text of DOI:10.1134/S1070363210010172

ISSN 1070-3632, Russian Journal of General Chemistry, 2010, Vol. 80, No. 1, pp. 127–132. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.P. Kozachenko, O.V. Shablykin, A.N. Vasilenko, V.S. Brovarets, 2010, published in Zhurnal Obshchei Khimii, 2010, Vol. 80,
No. 1, pp. 133–138.
Transformation of Substituted 5-Amino-1,3-oxazole-4-carbo-
nitriles into New 3,4,5-Triaminopyrazole Derivatives
A. P. Kozachenko, O. V. Shablykin, A. N. Vasilenko, and V. S. Brovarets
Institute of Bioorganic and Petroleum Chemistry, National Academy of Sciences of Ukraine,
ul. Murmanskaya 1, Kiev, 02660 Ukraine
e-mail: brovarets@bpci.kiev.ua
Received December 15, 2008
Abstract—Reactions of accessible 5-alkylamino- and 5-arylamino-1,3-oxazole-4-carbonitriles with hydrazine
hydrate on heating involved a complex transformation sequence resulting in the formation of 3,4,5-
triaminopyrazole derivatives. The structure of the products was confirmed by their cyclocondensation with
acetylacetone, leading to 2-alkyl(aryl)amino-3-acylamino-5,7-dimethylpyrazolo[1,5-a]pyrimidines which were
identified by NMR spectroscopy using COSY, NOESY, HMQC, and HMBC techniques.
DOI: 10.1134/S1070363210010172
We previously found that some 5-sulfanyl- and 5-
hydrazino-1,3-oxazole derivatives are capable of
undergoing recyclizations [1–9]. We now report on a
complex transformation of 5-amino-1,3-oxazole-4-
carbonitrile derivatives which were synthesized
according to the known method, cyclocondensation of
resulted in expected cyclocondensations V → VI and
V → VII with formation of the corresponding
pyrazolo[1,5-a]pyrimidine derivatives.
The structure of compound VIg (R1 = 4-MeC6H4,
R2 = 4-MeOC6H4) was unambiguously determined by
NMR spectroscopy using COSY, NOESY, HMQC, and
HMBC experiments (see figure, Table 3). From the
NOESY spectrum [δ 2.41 (4c-CH3)–7.34 ppm (3c-H,
5c-H)] we identified the 3c-H and 5c-H signals; the 2c-
H and 6c-H signals were identified using the COSY
spectrum [δ 7.34 (3c-H, 5c-H)–7.99 ppm (2c-H, 6c-
H)], and the NOESY data [δ 7.99 (2c-H, 6c-H)–
9.59 ppm (CONH)] allowed us to unambiguously
assign signals from the 4-CH3C6H4CONH fragment.
This assignment was also confirmed by heteronuclear
HMBC [δ 2.41 ppm (4c-CH3)–δC 141.96 ppm (C4c),
δ 7.34 ppm (3c-H, C5cH)–δC 132.12 (C1c), δ 7.99 ppm
(2c-H, 6c-H)–δC 166.98 ppm (CO), δ 7.99 ppm (2c-H,
6c-H)–δC 141.96 ppm (C4c)] and HMQC experiments
[δ 7.34 ppm (3c-H, 5c-H)–δC 129.36 ppm (C3c, C5c),
δ 7.99 ppm (2c-H, 6c-H)–δC 128.72 ppm (C2c, C6c)].
Likewise, signals belonging to the 4-CH3OC6H4NH
fragment were identified. Finally, HMBC correlations
between the CONH proton (δ 9.59 ppm) and carbon
nuclei resonating at δC 166.04 (CO), 93.39 (C3a),
153.20 (C2a), and 143.79 ppm (C3ab), as well as
between the NH proton (δ 8.19 ppm) and C3a (δC
93.32 ppm), C2a (δC 153.20 ppm), and C2d/C6d (δC
118.77 ppm), made it possible to assign signals
accessible 2-acylamino-3,3-dichloroacrilonitriles
І
with primary amines [10, 11]. The cyclization pro-
ducts, compounds II, possess a labile hydrogen atom
and, like other oxazoles functionalized at the 5-
position [12, 13], are obviously capable of being
converted into nonaromatic 5-imino-4,5-dihydro-1,3-
oxazole tautomers III. Reaction of the latter with
hydrazine hydrate on heating involves opening of the
oxazole ring and subsequent recyclization IV→V with
formation of triaminopyrazole derivatives.
Interestingly, condensation products of compounds
I with secondary amines, which are structurally related
to oxazoles II but possess no labile hydrogen atom, do
not react with hydrazine hydrate even on prolonged
heating. Nevertheless, despite the above limitation, the
scope of application of compounds I for the synthesis
of new 3,4,5-triaminopyrazole remains fairly broad
(Table 1). The presence in molecules V of a primary
amino group, acylamino residue, and alkyl- or
arylamino fragment is consistent with the spectral data
presented in Table 2. In addition, compounds V
undoubtedly contain an amidine moiety. Their
treatment with acetylacetone or ethyl acetoacetate
127

128
KOZACHENKO et al.
Table 1. Yields, melting points, and elemental analyses of compounds II, V, VII, and VIII
Found, %
Calculated, %
Comp.
no.
Yield, %
mp, °C (solvent)
Formula
C
H
N
C
H
N
59
64
69
62
63
60
66
73
68
70
71
72
69
66
65
70
81
75
75
77
78
73
76
64
72
130–132 (CHCl3)
211–213a (CHCl3)
215–217 (CHCl3)
198–200b (CHCl3)
215–218 (CHCl3)
196–198 (CHCl3)
181–184 (CHCl3)
229–232 (EtOH)
221–224 (EtOH)
231–233 (EtOH)
215–217 (EtOH)
205–207 (EtOH)
163–166 (EtOH)
129–132 (EtOH)
235–-238 (EtOH)
227–230 (EtOH)
210–212 (EtOH)
222–224 (EtOH)
228–230 (EtOH)
264–266 (EtOH)
243–245 (EtOH)
249–253 (EtOH)
244–246 (EtOH)
118–120 (EtOH)
115–118 (EtOH)
67.43
73.34
74.32
74.31
74.91
69.93
70.63
58.84
65.71
66.31
66.55
67.13
63.27
63.97
57.02
66.31
66.12
70.71
71.02
71.03
71.52
68.05
68.97
64.94
71.02
5.02
4.37
4.91
4.84
5.02
4.61
4.88
6.25
5.26
5.42
5.69
6.08
5.42
5.56
5.51
5.44
6.31
5.51
5.59
5.56
5.89
5.31
5.62
5.68
5.61
19.61
15.92
15.02
15.41
14.39
14.51
13.84
28.51
23.96
22.90
22.91
21.87
21.79
20.64
30.40
22.63
22.78
19.72
18.71
18.69
18.02
18.21
17.31
23.58
18.72
C12H11N3O
C16H11N3O
C17H13N3O
C17H13N3O
C18H15N3O
C17H13N3O2
C18H15N3O2
C12H15N5O
C16H15N5O
C17H17N5O
C17H17N5O
C18H19N5O
C17H17N5O2
C18H19N5O2
C11H13N5O
C17H17N5O
C17H19N5O
C21H19N5O
C22H21N5O
C22H21N5O
C23H23N5O
C22H21N5O2
C23H23N5O2
C16H17N5O
C22H21N5O
67.59
73.55
74.17
74.17
74.72
70.09
70.81
58.76
65.52
66.43
66.43
67.27
63.15
64.08
57.13
66.43
66.00
70.57
71.14
71.14
71.67
68.20
68.81
65.07
71.14
5.20
4.24
4.76
4.76
5.23
4.50
4.95
6.16
5.15
5.57
5.57
5.96
5.30
5.68
5.67
5.57
6.19
5.36
5.70
5.70
6.01
5.46
5.77
5.80
5.70
19.71
16.07
15.26
15.26
14.52
14.42
13.76
28.55
23.88
22.79
22.79
21.79
21.66
20.76
30.28
22.79
22.64
19.59
18.85
18.85
18.17
18.08
17.44
23.71
18.85
IIa
IIb
IIc
IId
IIe
IIf
IIg
Va
Vb
Vc
Vd
Ve
Vf
Vg
Vh
Vi
VIa
VIb
VIc
VId
VIe
VIf
VIg
VIh
VIi
86
87
88
336–339 (toluene)
>350 (acetone)
>350 (acetone)
61.60
66.71
67.81
5.39
4.61
5.29
22.32
19.62
18.92
C16H17N5O2
C20H17N5O2
C21H19N5O2
61.72
66.84
67.55
5.50
4.77
5.13
22.49
19.49
18.75
VIIa
VIIb
VIIc
88
331–333 (acetone)
67.71
5.28
18.89
C21H19N5O2
67.55
5.13
18.75
VIId
86
84
87
305–307 (acetone)
>350 (acetone)
68.38
64.89
65.38
5.62
5.07
5.12
18.29
18.13
17.21
C22H21N5O2
C21H19N5O3
C22H21N5O3
68.20
64.77
65.20
5.46
4.92
5.25
18.08
17.98
17.36
VIIe
VIIf
VIIg
311–314 (acetone)
85
86
324–326 (acetone)
318–320 (acetone)
60.48
67.38
4.96
4.98
23.69
18.93
C15H15N5O2
C21H19N5O2
60.60
67.55
5.09
5.13
23.56
18.75
VIIh
VIIi
a mp 210–211°C [11]. b mp 199–202°C [11].
belonging to the pyrazolopyrimidine system; the as-
signment was consistent with published data [14].
though numerous functional derivatives of that fused
heterocyclic system have already been reported (see
reviews [15–17] and recent publications [18–21]),
preparative importance of the proposed scheme II → V →
VI is beyond doubt. The structure of related compounds
VII was not proved specially, for regioselectivity in the
cyclizations of various 3(5)-aminopyrazoles with ethyl
acetoacetate was studied in detail previously [15–21].
To conclude, it should be noted that the trans-
formation V→VI attracts interest not only from the view-
point of structure determination of substituted 3,4,5-
triaminopyrazoles but also for the preparation of new
2,3-diaminopyrazolo[1,5-a]pyrimidine derivatives. Al-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 1 2010

TRANSFORMATION OF SUBSTITUTED 5-AMINO-1,3-OXAZOLE-4-CARBONITRILES
129
H
CN
N
R1
Cl
O
Cl
Iа−Ic
R2NH2 (excess) 20−25oC
CN
CN
N
N
R1
R1
NHR2
NR2
IIIа−IIIi
O
O
IIа−IIi
H2N-NH2·H2O
Δ
H
H
NH2
NH
1
1
R
N
CN
R
N
Δ
O
O
H
NH2
N
N
N
N
H
R2
R2
IVа−IVi
Vа−Vi
O
O
O
O
Me
Me
Me
OEt
Δ
Δ
Me
Me
H
HN
H
N
1
1
R
N
R
N
N
N
O
N
N
Me
O
H
O
H
N
N
R2
R2
VIа−VIi
VIIа−VIIi
I, R1 = Me (a), Ph (b), 4-MeC6H4 (c); II–VII, R1 = Me, R2 = 4-MeC6H4 (a); R1 = R2 = Ph (b); R1 = 4-MeC6H4, R2 = Ph (c);
R1 = Ph, R2 = 4-MeC6H4 (d); R1 = R2 = 4-MeC6H4 (e); R1 = Ph, R2 = 4-MeOC6H4 (f); R1 = 4-MeC6H4, R2 = 4-MeOC6H4 (g);
R1 = Ph, R2 = Me (h); R1 = Ph, R2 = PhCH2 (i).
EXPERIMENTAL
acrylonitrile Ia–Ic, 0.04 mol, was dissolved in 30 ml
of freshly distilled dimethylformamide, 0.16 mol of the
corresponding aromatic amine was added, and the
mixture was stirred for 120 h at 20–25°C. The mixture
was diluted with 50 ml of water, and the precipitate
was filtered off and purified by recrystallization.
The IR spectra were recorded in KBr on Vertex 70
1
spectrometer. The H NMR spectra were measured on
1
a Varian 300 spectrometer. The H–13C heteronuclear
correlation spectra were obtained on a Varian Mercury
400 instrument (400 and 100 MHz for H and 13C,
1
5-Benzyl(methyl)amino-2-phenyl-1,3-oxazole-4-
carbonitriles IIh and IIi were synthesized according
to the procedure described previously [10].
respectively) using DMSO-d6 as solvent and tetra-
methylsilane as internal reference.
2-Aryl(methyl)-5-arylamino-1,3-oxazole-4-carbo-
nitriles IIa–IIg (general procedure). Dichloro-
3-Alkyl(aryl)amino-5-amino-4-acylamino-1H-
pyrazoles Va–Vi (general procedure). Compound IIa–
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 1 2010

130
KOZACHENKO et al.
Table 2. IR and 1H NMR spectra of compounds II, V, VII, and VIII
Comp.
no.
IR spectrum (KBr), ν, cm–1
1H NMR spectrum (DMSO-d6), δ, ppm
7.07–7.89 m (10H, 2C6H5), 10.57 s (1H, NH)
2228 (C=N), 3130–3300 (NHas)
IIb
2220 (C=N), 3115–3340 (NHas)
2213 (C=N), 3190–3325 (NHas)
2.37 s (3H, CH3), 7.10–7.77 m (9H, C6H5, C6H4), 10.56 s (1H, NH)
2.31 s (3H, CH3), 7.14–7.85 m (9H, C6H5, C6H4), 10.42 s (1H, NH)
IIc
IId
2214 (C=N), 3110–3310 (NHas)
2230 (C=N), 3120–3290 (NHas)
2218 (C=N), 3100–3220 (NHas)
1640a [NC=O, δ(NH2)], 3050–3360
2.31 s (3H, CH3), 2.38 s (3H, CH3), 7.14–7.73 m (8H, 2C6H4), 10.40 s (1H, NH)
3.77 s (3H, CH3), 6.91–7.84 m (9H, C6H5, C6H4), 10.36 s (1H, NH)
IIe
IIf
IIg
Va
2.38 s (3H, CH3), 3.77 s (3H, CH3), 6.90–7.72 m (8H, 2C6H4), 10.26 s (1H, NH)
1.97 s (3H, CH3), 2.19 s (3H, CH3), 4.51 br. s (2H, NH2), 6.89–7.18 m (4H, 2 C6H4),
7.12 s (1H, NH, pyrazole), 8.74 s (1H, CONH), 10.53 br.s (1H, NH)
(NH, NH2 as
)
1628a [NC=O, δ(NH2)], 3100–3350
(NH, NH2 as
4.66 br.s (2H, NH2), 6.65 br.s (1H, NH), 7.10–7.97 m (10H, 2C6H5), 9.30 s (1H,
CONH), 10.77 br.s (1H, NH, pyrazole)
Vb
)
–
2.39 s (3H, CH3), 4.65 br.s (2H, NH2), 6.65 br.s (1H, NH), 7.07–7.87 m (9H, C6H5,
C6H4), 9.23 s (1H, CONH), 10.74 br.s (1H, NH, pyrazole)
Vc
–
2.17 c (3H, CH3), 4.74 c (2H, NH2), 6.92–7.98 m (9H, C6H5, C6H4), 7.29 br.s (1H,
NH), 9.25 s (1H, CONH), 10.71 s (1H, NH, pyrazole)
Vd
1637a (NC=O), 3100–3350 (NH, NH2 as
)
)
2.19 c (3H, CH3), 2.39 s (3H, CH3), 4.61 br.s (2H, NH2), 6.89–7.87 m (8H, 2 C6H4),
7.2 br.s (1H, NH), 9.19 s (1H, CONH), 10.66 br.s (1H, NH, pyrazole)
Ve
1634a (NC=O), 3120–3345 (NH, NH2
as.)
3.67 s (3H, CH3), 4.63 br.s (2H, NH2), 6.71–7.97 m (9H, C6H4, C6H5), 7.25 br.s (1H,
NH), 9.27 s (1H, CONH), 10.62 br.s (1H, NH, pyrazole)
Vf
–
2.77 s (3H, CH3), 3.67 s (3H, CH3), 4.56 br.s (2H, NH2), 6.69–7.86 m (8H, 2C6H4),
7.15 br.s (1H, NH), 9.12 s (1H, CONH), 10.54 br.s (1H, NH, pyrazole)
2.75 s (3H, CH3), 7.42–7.95 m (5H, C6H5), 9.19 s (1H, CONH)b
Vg
1639a (NC=O), 3150–3380 (NH, NH2 as
Vh
–
4.26 d (2H, CH2), 4.52 br.s (2H, NH2), 5.07 s (1H, NH), 7.16–7.93 m (10H, 2 C6H5),
9.24 s (1H, CONH), 10.31 br.s (1H, NH, pyrazole)
Vi
1642 (NC=O), 3050–3190 (NHas)
2.09 s (3H, CH3), 2.25 s (3H, CH3), 2.44 s (3H, CH3), 2.62 s (3H, CH3), 6.56 s (1H,
3-H, pyrimidine), 7.02–7.54 m (4H, C6H4), 8.02 s (1H, CONH), 9.34 s (1H, NH)
VIa
VIb
VIc
VId
VIe
VIf
VIh
VIi
VIIa
1634 (NC=O), 3200–3400 (NHas)
2.45 s (3H, CH3), 2.68 s (3H, CH3), 6.61 (1H, 3-H, pyrimidine), 6.81 br.s (1H, NH),
7.19–8.25 m (10H, 2 C6H5), 9.67 s (1H, CONH)
–
2.42 s (6H, 2 CH3), 2.66 s (3H, CH3), 6.68 s (1H, 3-H, pyrimidine), 6.84 br.s (1H,
NH), 7.23–8.36 m (9H, C6H5, C6H4), 9.61 s (1H, CONH)
–
2.23 s (3H, CH3), 2.42 s (3H, CH3), 2.65 s (3H, CH3), 6.67 s (1H, 3-H, pyrimidine),
7.07 sh.s (1H, NH), 7.53-8.25 m (9H, C6H5, C6H4), 9.66 s (1H, CONH)
1630 (NC=O), 3150–3300 (NHas)
2.25 s (3H, CH3), 2.43 s (6H, 2 CH3), 2.66 s (3H, CH3), 6.59 s (1H, 3-H, pyrimidine),
7.00 br.s (1H, NH), 7.03–8.11 m (8H, 2 C6H4), 9.58 s (1H, CONH)
–
2.43 s (3H, CH3), 2.65 s (3H, CH3), 3.72 s (3H, CH3), 6.56 s (1H, 3-H, pyrimidine),
6.81 br.s (1H, NH), 7.48–8.09 m (9H, C6H5, C6H4), 9.62 s (1H, CONH)
1642 (NC=O), 3050–3220 (NHas)
–
2.38 s (3H, CH3), 2.57 s (3H, CH3), 2.89 s (3H, CH3), 5.40 br.s (1H, NH), 6.42 s (1H,
3-H, pyrimidine), 7.43–8.04 m (5H, C6H5), 9.62 s (1H, CONH)
2.73 s (3H, CH3), 2.54 s (3H, CH3), 4.51 br.s (2H, CH2), 5.99 br.s (1H, NH), 6.45 s
(1H, 3-H, pyrimidine), 7.18–8.05 m (10H, 2 C6H5), 9.67 s (1H, CONH)
1648 (NC=O), 1685 (C=O), 3160–3390 2.05 s (3H, CH3), 2.25 s (3H, CH3), 5.41 s (1H, 3-H, pyrimidine), 7.02–7.58 m (4H,
(NHas)
C6H4), 7.89 s (1H, NH), 8.89 s (1H, CONH) 11.34 s (1H, NH, pyrimidine)
–
–
2.25 c (3H, CH3), 2.40 c (3H, CH3), 5.52 c (1H, 3-H, pyrimidine), 6.84 br.s (1H, NH),
7.22–8.32 m (9H, C6H5, C6H4), 9.43 s (1H, CONH), 11.63 s (1H, NH, pyrimidine)
VIIc
VIId
2.25 s (6H, 2 CH3), 5.52 s (1H, 3-H, pyrimidine), 7.05 br.s (1H, NH), 7.08–8.21 m
(9H, C6H5, C6H4), 9.48 s (1H, CONH), 11.60 s (1H, NH, pyrimidine)
1653 (NC=O), 1688 (C=O), 3100–3350 2.25 s (6H, 2 CH3), 2.42 s (3H, CH3), 5.43 s (1H, 3-H, pyrimidine), 6.95 br.s (1H,
VIIe
(NHas)
NH), 7.03–8.06 m (8H, 2C6H4), 9.37 s (1H, CONH), 11.44 s (1H, NH, pyrimidine)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 1 2010

TRANSFORMATION OF SUBSTITUTED 5-AMINO-1,3-OXAZOLE-4-CARBONITRILES
Table 2. (Contd.)
131
Comp.
no.
IR spectrum (KBr), ν, cm–1
1H NMR spectrum (DMSO-d6), δ, ppm
1650 (NC=O), 1692 (C=O), 3120–3340 2.25 s (3H, CH3), 3.71 s (3H, CH3), 5.42 s (1H, 3-H, pyrimidine), 6.79 br.s (1H, NH),
VIIf
(NHas)
6.82–8.08 m (9H, C6H5, C6H4), 9.43 s (1H, CONH), 11.42 s (1H, NH, pyrimidine)
–
2.24 s (3H, CH3), 2.40 s (3H, CH3), 3.70 s (3H, CH3), 5.48 s (1H, 3-H, pyrimidine),
6.84 br.s (1H, NH), 6.87–8.08 m (8H, 2 C6H4), 9.37 s (1H, CONH), 11.54 s (1H, NH,
pyrimidine)
VIIg
1646 (NC=O), 1687 (C=O), 3110–3320 2.21 s (3H, CH3), 2.81 s (3H, CH3), 5.32 s (1H, 3-H, pyrimidine), 5.40 br.s (1H, NH),
(NHas) 7.50–8.02 m (5H, C6H5), 9.36 s (1H, CONH), 11.24 s (1H, NH, pyrimidine)
1654 (NC=O), 1685 (C=O), 3100–3350 2.21 s (3H, CH3), 4.44 d (2H, CH2), 5.39 s (1H, 3-H, pyrimidine), 6.11 br.s (1H, NH),
(NHas) 7.21–8.04 m (10H, 2 C6H5), 9.42 s (1H, CONH), 11.38 s (1H, NH, pyrimidine)
VIIh
VIIi
a
Band with a shoulder. b Protons in the NH and NH2 groups are exchangeable.
Table 3. Correlations in the COSY, NOESY, HMQC, and HMBC spectra of compound VIga
1H, δ, ppm
13C, δC, ppm
HMBC
129.36(C3c, C5c), 141.96(C4c)
1H, δ, ppm
COSY
–
NOESY
7.34
HMQC
24.67
2.41(CH3C4c)
7.34 (C3cH, C5cH)
7.99 (C2cH, C6cH)
9.59 (CONH)
2.41 (CH3C5b)
6.64 (C6bH)
7.99
7.34
–
2.41
9.59
7.99
6.64
129.36
128.72
–
129.36 (C3c, C5c), 132.12 (C1c), 24.67(CH3C4c)
128.72 (C2c, C6c), 141.96 (C4c), 166.98 (CO)
166.04 (CO), 93.39 (C3a), 153.20(C2a), 143.79(C3ab
158.62 (C5b), 106.65 (C6b)
)
–
21.72
106.65
16.80
–
–
2.41, 2.64
6.64
158.62 (C5b), 145.03(C7b), 21.72(CH3C5b), 16.80(CH3C7b)
145.03 (C7b), 106.65 (C6b)
2.64 (CH3C7b)
–
8.19 (NH)
–
7.69
93.32(C3a), 153.20(C2a), 118.77(C2d, C6d)
118.77(C2d, C6d), 153.60(C4d)
7.69 (C2dH, C6dH)
6.87 (C3dH, C5dH)
3.71 (CH3O)
6.87
7.69
–
8.19
118.77
114.57
55.80
3.71
114.57(C3d, C5d), 136.14(C1d)
6.87
153.60(C4d)
a
For atom numbering, see figure.
IIi, 0.005 mol, was dissolved in 10 ml of ethylene
glycol, 0.015 mol of hydrazine hydrate was added, and
the mixture was heated for 3 h at 160–170°C. After
cooling, the mixture was diluted with 50 ml of water,
and the precipitate was filtered off and purified by
recrystallization.
cedure). Compound Va–Vi, 0.001 mol, was dissolved
in 5 ml of toluene, 5 ml of ethyl acetoacetate was
added, and the mixture was heated for 2 h under reflux.
The precipitate was filtered off and purified by
recrystallization.
REFERENCES
2-Alkyl(aryl)amino-3-acylamino-5,7-dimethyl-
pyrazolo[1,5-a]pyrimidines VIa-VIi (general pro-
cedure). Compound Va–Vi, 0.001 mol, was dissolved
in 5 ml of toluene, 5 ml of acetylacetone was added,
and the mixture was heated for 2 h under reflux. The
precipitate was filtered off and purified by re-
crystallization from ethanol.
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KOZACHENKO et al.
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