424 JOURNAL OF CHEMICAL RESEARCH 2007
Table 2 IR and 1H NMR spectra of the some newly synthesis compounds
compd No.
Spectral data
9
IR (KBr): 3235 (NH) and 1610 (c=N).
1H NMR: 7.21–7.7 (m, 14H, ArHs) and 8.51 (s, 1H, NH).
IR (KBr): 3311 (NH), 2921(cH3), 1718 (c=O) and 1645 (c=N).
1H NMR (cDcl3): 1.3 (t, 3H, cH3 cH2), 3.20 (s, 1H, cH3), 4.4 (q, 2H, cH2cH3), 7.2–7.9 (m, 10H, ArHs and NH) and
11.3 (s, 1H, NH).
16
17
18
IR (KBr): 3297 (NH), 1694 (c=O), 1644 (c=N) and 1600 (c=c).
IR (KBr): 3297, 3156 (NH2) and 2227 (cN).
1H NMR (cDcl3): 7.08–8.9 (m, 9H, ArHs) and 9.40 (s, 1H, NH).
IR (KBr): 3399, 3285 (NH2), 2925 (cH-aliphatic), 1676 (cO) and 1622 (c=N).
1H NMR (cDcl3): 5.2 (s, br, 2H, NH2) and 7.10–7.90 (m, 14H, ArHs).
IR (KBr): 3403, 3294 (NH2), 1653 (cO) and 1621 (c=N).
1H NMR (cDcl3, ä ppm): 2.5 (s, 1H, cH3), 6.9 (s, 2H, NH2) and 7.3–7.9 (m, 9H, ArHs).
IR (KBr): 3400–3290 (NH2), 1650 (cO).
21b
21c
21d
23b
23c
1H NMR (cDcl3): 6.9 (s, 2H, NH2) and 7.3–7.7 (m, 14H, ArHs).
IR (KBr): 2223 (cN) and 1608 (c=N).
1H NMR (cDcl3): 2.31 (s, 3H, cH3), 7.23–7.77 (m, 8H, ArHs) and 9.34 (s, 1H, NH).
IR (KBr): 2231 (cN), 1604 (c=N).
1H NMR (cDcl3): 7.22–7.70 (m, 9H, ArHs) and 9.34 (s, 1H, NH).
IR (KBr): 2220 (cN), 1700 (c=O), 1664 (c=N).
23d
24b
IR (KBr): 3459, 3349 (NH2) and 1640 (cO).
1H NMR (ä cDcl3): 1.21 (t, 3H, cH3-cH2), 2.35 (s, 3H, p-cH3), 4.22 (q, 2H, cH2-cH3), 5.60 (s, 2H, NH2) and 7.30–7.8
(m, 9H, ArHs).
24c
24d
24e
24f
30
IR (KBr): 3498, 3390 (NH2) and 1720 (cO).
1H NMR (cDcl3): 1.15 (t, 3H, cH3-cH2), 4.22 (q, 2H, cH2-cH3), 5.25 (s, 2H, NH2) and 7.20–7.55 (m, 8H, ArHs).
IR (KBr): 3459, 3349 (NH2) and 1640 (cO).
1H NMR (cDcl3): 5.15 (s, 2H, NH2) and 7.20–7.81 (m, 14H, ArHs).
IR (KBr): 3465, 3359 (NH2) and 1634 (cO).
1H NMR (cDcl3): 2.35 (s, 3H, cH3), 5.18 (s, 2H, NH2) and 7.20–7.81 (m, 13H, ArHs).
IR (KBr): 3450, 3249 (NH2) and 1640 (cO).
1H NMR (cDcl3): 5.55 (s, 2H, NH2) and 7.20–7.81 (m, 13H, ArHs).
IR (KBr, cm-1): 3350, 3280 (NH2) and 1630 (c=N).
1H NMR (cDcl3): 6.25 (s, 2H, NH2) and 7.20–7.55 (m, 8H, ArHs).
7-amino-2-(benzoxazol-2-yl)-5-phenyl-2(phenylamino)-4,5-
dihydropyrazolo[1,5-a]pyrimidine-6-carbonitrile (7): Method A:
A mixture of 2 (2.91 g, 10 mmol) and 1,1-dicyano-2-phenylethene
(1.5 g, 10 mmol), in ethanol (50 ml) with catalytic amount of piperidine
(three drops) was refluxed for 3 h. The resulting product was collected
by filtration and crystallised from benzene to give 7 (Tables 1
and 2). Method B: A mixture of 9 (3.7 g, 10 mmol), malononitrile
(0.66 g, 10 mmol) and piperidine (three drops) in ethanol (20 ml) was
refluxed for 3 h. The solid, so formed was collected and crystallised
from benzene to give product identical in all aspects (m.p., mixed,
and spectra) with compound obtained in method A. Method C:
A mixture of 2 (2.91 g, 10 mmol), benzaldehyde (1.06 g, 10 mmol)
and malononitrile (0.66 g, 10 mmol) and piperidine (three drops)
in ethanol (10 ml) was refluxed for 4 h. The solid, so formed was
collected and crystallised from benzene to give product identical in
all aspects (m.p., mixed, and spectra) with compound obtained from
each method A or B.
3-(Benzoxazol-2-yl)-7-oxo-5-phenyl-2-(phenylamino)-4,5,6,7-
tetrahydropyrazolo[1,5-a]pyrimidine-6-carbonitrile (10): A mixture
of 2 (2.91 g, 10 mmol), ethyl α-cyanocinnamate (2.01 g, 10 mmol) in
ethanol (50 ml) with 3–5 drops piperidine, the reaction mixture was
refluxed for 3 h. The resulting solid was collected and recrystallised
from ethanol to give 10 (Tables 1 and 2).
Synthesis of pyrazolo[5,1-c][1,2,4]-triazines 15–18: Dissolve
2 (2.91 g, 10 mmol) in hydrochloric acid (6 ml, 6N) and cooled
at 0–5°C. Sodium nitrite (0.69 g, 10 mmol) in water (10 ml) was
added dropwise while stirring for 10 min. The diazonium salt was
added to mixture containing the appropriate of acetylacetone, ethyl
acetoacetate, malonitrile or ethyl cyanoacetate and sodium acetate
(1.3 g, 10 mmol) in ethanol (50 ml) at 0–5°C, and the reaction mixture
was stirred at 0–5°C for 3 h. The solid was collected and crystallised
from the appropriate solvent to give compounds 15–18, respectively
(Tables 1 and 2).
2-(benzoxazol-2-yl)ethanenitrile (19) (1.58 g, 10 mmol) in ethanol
(20 ml) containing sodium acetate trihydrate (1.3 g, 10 mmol).
The appropriate diazonium chloride, prepared by adding sodium
nitrite (0.69 g, 10 mmol in water) to a cold solution of the appropriate
aromatic amine (10 mmol) or 4-amino-antiprine in hydrochloric acid
(6 ml, 6 N) was added while stirring for 1 h. The resulting solid was
collected and recrystallised from ethanol to give compounds 23a-d,
respectively (Tables 1 and 2).
Synthesis of 4-aminopyrazole derivatives 24a–f: General
procedure: A mixture of the appropriate 23a–c (10 mmol) in N,N-
dimethylformamide (20 ml), anhydrous potassium carbonate
(2.66 g, 20 mmol), and appropriate weight of ethyl chloroacetate
(1.06 ml, 10 mmol) heated at 120°C about 2 h, then cooled at 80–
90°C. Triethylamine (1 ml) was added and the reaction mixture was
heated at 90°C for 1 h. The reaction mixture was cooled and poured
onto ice cold water (150–160 ml). The resulting solid was collected
and recrystallised from the proper solvent to give 4-aminopyrazoles
24a–c, respectively (Tables 1 and 2). Also, using phenacyl bromide
(1.9 g, 10 mmol) in stead ethyl chloroacetate, the 4-aminopyrazoles
24e–f were obtained (Tables 1 and 2).
3-(Benzoxazol-2-yl)-7-phenylpyrazolo[5,1-c][1,2,4]triazin-4-yl
amine (29): Diazotised 3-amino-5-phenylaminopyrazole (25)
[prepared by adding sodium nitrite solution (0.69 g, 10 mmol) in
water (10 ml) to a mixture of aminopyrazole (1.58 g, 10 mmol),
hydrochloric acid (6 ml, 6 N) and acetic acid (1 ml) at 0°C] was
added to a mixture of (benzoxazole-2-yl)ethanenitril (19) (1.58 g,
0.01 mol), sodium acetate (1.3 g) in ethanol (50 ml) at 0–5°C for 1 h.
The solid was collected by filtration, washed and with water and
crystallised from dioxan to give 29 (Tables 1 and 2).
3-(Benzoxazol-2-yl)-[1,2,4]-triazino[4,3-a]benzimidazol-4-amine
(30): 2-Aminobenzimidazolediazonium sulfate 26 (10 mmol) was
added dropwise to a cold solution of 2-(benzoxazol-2-yl)ethanenitrile
(19) (1.58 g, 10 mmol) in ethanol (50 ml) containing sodium acetate
trihydrate (1.3 g, 10 mmol) while stirring. The reaction mixture
was stirred at 0–5°C for 1 h. The resulting product was collected by
filtration and recrystallised from N,N-dimethylformamide to give 30
(Tables 1 and 2).
Synthesis of 5-aminopyrazole derivatives 21a–d: General
procedure: The appropriate hydrazonoyl halide 20a-d (10 mmol)
added to a mixture of 2(benzoxazol-2-yl)ethanenitrile (19) (1.58 g,
10 mmol) and sodium ethoxide (sodium 0.21 g-atom in ethanol
(20 ml)). The above mixture was stirred for 30 min. and left to stand
overnight. The solid was collected by and crystallised from the proper
solvent to give pyrazoles 21a–d, respectively (Tables 1 and 2).
Synthesis of 3-aza-2-(benzoxazole-2-yl)-3-(4-substituted)prop-
2-enenitrile 23a–d: General procedure: To a cold solution of
Received 31 May 2007; accepted 9 July 2007
Paper 07/4678 doi: 10.3184/030823407X228830
PAPER: 07/4678
Abdelhamid, Abdou O.
