Synthesis of fluorinated 2(3)-arylhydrazones of 1,2,3-tri(1,2,3,4-tetra)carbonyl compounds and their heterocyclization reactions

Article abstract of DOI:10.1016/S0022-1139(98)00247-4

New fluorinated 2-arylhydrazones of 1,2,3-triketones, 2-arylhydrazone-1,2,3-diketo esters and 3-arylhydrazone-1,2,3,4-triketo esters have been prepared by the coupling of fluorine-containing 1,3-keto esters, 1,3-diketones, acyl(aroyl)pyruvic esters and their chelates with aryldiazonium chlorides. The arylhydrazones react with hydrazine hydrate, phenylhydrazine, thiosemicarbazide and hydroxylamine to form the corresponding pyrazole and isoxazole derivatives. Interaction of 3-arylhydrazone-1,2,3,4-diketo esters with o-phenylenediamine results in quinoxaline products. Intramolecular cyclization of the arylhydrazones with pentafluorophenyl substituents leads to cinnolone derivatives.

Full text of DOI:10.1016/S0022-1139(98)00247-4

Journal of Fluorine Chemistry 92 (1998) 101±108
Synthesis of ¯uorinated 2(3)-arylhydrazones of
1,2,3-tri(1,2,3,4-tetra)carbonyl compounds and
their heterocyclization reactions
Y.V. Burgart, A.S. Fokin, O.G. Kuzueva, O.N. Chupakhin, V.I. Saloutin*
Institute of Organic Synthesis, Urals Division, Russian Academy of Sciences, 620219, GSP-147, Ekaterinburg, Russia
Received 17 April 1998; accepted 7 July 1998
Abstract
New ¯uorinated 2-arylhydrazones of 1,2,3-triketones, 2-arylhydrazone-1,2,3-diketo esters and 3-arylhydrazone-1,2,3,4-triketo esters
have been prepared by the coupling of ¯uorine-containing 1,3-keto esters, 1,3-diketones, acyl(aroyl)pyruvic esters and their chelates with
aryldiazonium chlorides. The arylhydrazones react with hydrazine hydrate, phenylhydrazine, thiosemicarbazide and hydroxylamine to form
the corresponding pyrazole and isoxazole derivatives. Interaction of 3-arylhydrazone-1,2,3,4-diketo esters with o-phenylenediamine results
in quinoxaline products. Intramolecular cyclization of the arylhydrazones with penta¯uorophenyl substituents leads to cinnolone
derivatives. # 1998 Published by Elsevier Science S.A.
Keywords: Coupling; Fluoroalkyl-containing 1,3-diketone; 1,3-keto ester; Acyl(aroyl)pyruvate; Arylhydrazone; Pyrazole; Isoxazole; Quinoxaline;
Cinnolone
1. Introduction
Specord 75 IR spectrometer. 1H-NMR spectra were
recorded on a Tesla BS-567A instrument (1H: 100 MHz)
using TMS as an internal standard. 19F-NMR spectra were
recorded on a Tesla BS-587A instrument (19F: 75 MHz)
using CFCl3 as an internal standard. Microanalyses were
performed with a Carlo Erba CHNS-O EA 1108 elemental
analyzer. Column chromatography was performed on silica
gel L 100/250. Thin-layer chromatography was performed
on `Silufol-UV 254' plates.
It is known that 1,3-dicarbonyl compounds react with
aryldiazonium salts to form the corresponding 2-arylhydra-
zone-1,2,3-tricarbonyl compounds [1]. Data on the coupling
of ¯uorine-containing 1,3-dicarbonyl compounds are avail-
able only for the reactions of a few ¯uorinated 1,3-diketones
[2,3], tri¯uoroacetoacetic [2] and penta¯uorobenzoylacetic
[4] esters. Information on the synthesis of arylhydrazones
from ¯uorinated acyl(aroyl)pyruvic esters are absent
(although their non-¯uorinated analogues are known [5]).
In our view ¯uorine-containing 2-arylhydrazone-1,2,3-
diketo esters, 2-arylhydrazones of 1,2,3-triketones, 3-aryl-
hydrazone-1,2,3,4-triketo esters may serve as key precursors
to a variety of novel heterocycles and react with dinucleo-
philes as non-substituted analogues [6±8].
2.1. Materials
Fluorinated keto esters 1a,b and their copper (II) chelates
4d,e were prepared by the method described previously
[9,10]. Fluorinated diketones 2a,b and copper (II) chelate
5a were derived according to the literature methods [9,11].
Tri¯uoroacetopyruvic esters 3a,d and copper (II) chelate 6a
were prepared by the method described previously [12].
Penta¯uorobenzoylpyruvic ester 3e and its copper 6e and
sodium 6h chelates were prepared from penta¯uorochloro-
benzene via described procedures [13,14].
This paper describes the synthesis of novel ¯uorinated 2-
arylhydrazones of 1,2,3-triketones, 2-arylhydrazone-1,2,3-
diketoesters, 3-arylhydrazone-1,2,3,4-triketoesters and their
heterocyclization reaction products.
2. Experimental details
2.2. Synthesis of 2-arylhydrazone-1,2,3-tricarbonyl
compounds
Melting points were measured in open capillaries and are
reported uncorrected. Infrared spectra were measured on a
A solution of the appropriate arylamine (1.1 mmol) in a
solution of 1 M HCl (50 ml) was diazotized at 0±58C by
*Corresponding author.
0022-1139/98/$ ± see front matter # 1998 Published by Elsevier Science S.A.
P I I : S 0 0 2 2 - 1 1 3 9 ( 9 8 ) 0 0 2 4 7 - 4

102
Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
addition of a saturated solution of NaNO2 (1.1 mol) in 10 ml
of water. The solution of aryldiazonium salt was added
dropwise to a solution of the dicarbonyl compound
(1 mmol) in 10 ml of methanol at 10±128C. To the solution
a saturated aqueous solution of NaOAc was added. The
resulting precipitate was ®ltered off. Recrystallization from
isopropyl alcohol gave compounds 7a±e, 8a±d, 9a±h as
yellow precipitates.
(1H, br.s, NH) ppm. 19F-NMR (CDCl3)) ꢀ: 38.72 (2F, m,
CF2); 51.22 (2F, m, CF2); 83.78 (3F, m, CF3) ppm. IR: 2730,
1615 (NH); 1685 (CO2Et), 1660 (C=O); 1600, 1520±1500
(C=C, C=N) cm 1. Analysis: Found: C, 41.49; H, 2.79; F,
32.80; N, 6.76. Calc. for C12H11F3N2O4: C, 41.60; H, 2.74;
F, 32.90; N, 6.93%.
2.2.6. 1,1,1-Trifluoro -2,3,4-pentanetrione
3-(p-methoxyphenyl)hydrazone (8a) (nc)
2.2.1. Ethyl-2-(p-methoxyphenyl)hydrazone-4,4,4-
trifluoro-2,3-dioxobutanoate (7a) (nc)
Yield, 70%; m.p. 116±1178C; 1H-NMR (CDCl3) ꢀ: 2.61
(3H, s, CH3); 3.84 (3H, s, CH3); 7.20 (4H, m, C6H4); 15.40
(1H,br.s,NH) ppm.19F-NMR(CDCl3)ꢀ:91.66(s,CF3) ppm.
IR: 2710, 1615 (NH); 1685 (C=O); 1590, 1500 (C=C,
C=N) cm 1. Analysis: Found: C, 50.07; H, 3.84; F,
19.83; N, 9.68. Calc. for C12H11F3N2O4: C, 50.01; H,
3.85; F, 19.77; N, 9.72%.
Yield, 73%; m.p. 135±1368C; 1H-NMR ((CD3)2CO)
ꢀ: 1.36 (3H, t, CH3, J(H±H)ˆ7.1 Hz); 3.86 (3H, s, CH3);
4.37 (2H, q, CH2, J(H±H)ˆ7.1 Hz); 7.30 (4H, m, C6H4); 9.0
(1H, br.s, NH) ppm. 19F-NMR ((CD3)2CO) ꢀ: 93.72
(s, CF3) ppm. IR: 3070, 1600 (NH); 1690 (CO2Et); 1650
(C=O); 1580, 1520, 1510 (C=C, C=N) cm 1. Analysis:
Found: C, 49.05; H, 4.06; F, 17,97; N, 8.93. Calc. for
C13H13F3N2O4: C, 49.06; H, 4.12; F, 17,91; N, 8.80%.
From chelate 5a (0.18 g, 1.0 mmol) compound 8a
(0.14 g, yield, 50%) was obtained. The physicochemical
data were identical to those listed above.
2.2.2. Ethyl-2-(p-methoxyphenyl)hydrazone-4,4,5,5,6,6,
7,7,7-nonafluoro-2,3-dioxoheptanoate (7b) (nc)
2.2.7. 1,1,2,2-Tetrafluoro-3,4,5-hexanetrione
4-(p-methoxyphenyl)hydrazone (8b) (nc)
Yield, 85%; m.p. 130±1318C; H-NMR ((CD3)2CO) ꢀ:
2.56 (3H, s, CH3); 3.87 (3H, s, CH3); 6.71 (1H, t.t, H(CF2)2,
Yield, 81%; m.p. 77±788C; 1H-NMR ((CD3)2CO) ꢀ: 1.36
(3H, t, CH3, J(H±H)ˆ7.0 Hz); 3.86 (3H, s, CH3); 4.38 (2H, q,
CH2, J(H±H)ˆ7.0 Hz); 7.30 (4H, m, C6H4); 13.43 (1H, br.s,
NH) ppm. IR: 3090, 1615 (NH); 1685 (CO2Et); 1660
(C=O); 1600, 1520, 1500 (C=C, C=N) cm 1. Analysis:
Found: C, 40.97; H, 3.13; F, 36.81; N, 5.95. Calc. for
C16H13F9N2O4: C, 41.04; H, 2.80; F, 36.51; N, 5.98%.
1
JꢀCF
ˆ52.8, JꢀCF
ˆ7.3 Hz); 7.30 (4H, m, C6H4);
H†
CHF2†
2
2
13.30 (1H, br.s, NH) ppm. 19F-NMR ((CD3)2CO) ꢀ: 26.65
(2F, d.t, HCF2, JꢀCF ˆ52.8, JꢀCF ˆ7.3 Hz); 44.02
H†
CHF2†
2
2
(2F, d.t, CF2, JꢀCF ;CF †ˆ7.3 Hz) ppm. IR: 2720, 1615 (NH);
2
2
1670 (C=O); 1590, 1580, 1500 (C=C, C=N) cm 1. Analy-
sis: Found: C, 48.53; H, 3.83; F, 24.09; N, 8.51. Calc. for
C12H11F3N2O4: C, 48.76; H, 3.78; F, 23.73; N, 8.75%.
2.2.3. Ethyl-2-(p-methylphenyl)hydrazone-4,4,5,5,6,
6,7,7,7-nonafluoro-2,3-dioxoheptanoate (7c) (nc)
1
Yield, 75%; m.p. 43±458C; H-NMR (CDCl3) ꢀ: 1.40
2.2.8. 1,1,2,2-Tetrafluoro-3,4,5-hexanetrione
4-(p-methylphenyl)hydrazone (8c) (nc)
(3H, t, CH3, J(H±H)ˆ7.1 Hz); 2.35 (3H, s, CH3); 4.38 (2H, q,
CH2, J(H±H)ˆ7.1 Hz); 7.24 (4H, m, C6H4); 13.5 (1H, br.s,
NH) ppm. 19F-NMR (CDCl3) ꢀ: 36.84 (2F, m, CF2); 41.26
(2F, m, CF2); 50.44 (2F, m, CF2); 81.10 (3F, s, CF3) ppm. IR:
3100, 1600 (NH); 1690 (CO2Et); 1660 (C=O); 1590, 1520,
1510 (C=C, C=N) cm 1. Analysis: Found: C, 42.59; H,
3.29; F, 37.57; N, 6.16. Calc. for C16H13F9N2O3: C, 42.49;
H, 2.90; F, 37.81; N, 6.19%.
1
Yield, 80%; m.p. 90±918C; H-NMR (CDCl3) ꢀ: 2.39
(3H, s, CH3); 3.61 (3H, s, CH3); 6.35 (1H, t.t, H(CF2)2,
JꢀCF
ˆ53.3, JꢀCF
ˆ6.7 Hz); 7.30 (4H, m, C6H4);
H†
HCF2†
2
2
15.25 (1H, br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 25.06
(2F, d.t, HCF2, J ˆ7.3 Hz); 44.26
ˆ53.3, JꢀCF
ꢀCF2 H†
ꢀCF2;CF2†
HCF2†
2
(2F, d.t, CF2, J
(NH); 1680 (C=O); 1580, 1510±1500 (C=C, C=N) cm
ˆ6.7 Hz) ppm. IR: 3370, 1600
1
.
Analysis: Found: C, 51.42; H, 3.93; F, 24.77; N, 9.29.
Calc. for C12H11F3N2O4: C, 51.32; H, 3.98; F, 24.98; N,
9.21%.
2.2.4. Methyl-2-(p-methoxyphenyl)hydrazone-4,4,4-
trifluoro-2,3-dioxobutanoate (7d) (nc)
Yield, 72%; m.p. 142±1448C; 1H-NMR (CDCl3) ꢀ: 3.86
(3H, s, CH3); 3.94(3H, s, CH3); 7.08 (4H, m, C6H4); 14.4
(1H, br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 96.72
(s, CF3) ppm. IR: 3080, 1605 (NH); 1700 (CO2Et); 1650
(C=O); 1590, 1520, 1500 (C=C, C=N) cm 1. Analysis:
Found: C, 47.31; H, 3.69; F, 18.62; N, 9.23. Calc. for
C12H11F3N2O4: C, 47.38; H, 3.64; F, 18.73; N, 9.21%.
2.2.9. 1,1,2,2-Tetrafluoro-3,4,5-hexanetrione
4-phenylhydrazone (8d) (nc)
Yield, 74%; m.p. 125±1268C; 1H-NMR (CDCl3) ꢀ: 2.62
(3H, s, CH3); 6.35 (t.t, 1H, H(CF2)2, J
JꢀCF
ˆ53.2,
ꢀCF2 H†
ˆ6.6 Hz); 7.44 (4H, m, C6H4); 15.20 (1H,
HCF2†
2
br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 24.96 (2F, d.t,
HCF2, JꢀCF ˆ53.2, JꢀCF ˆ6.6 Hz); 44.26 (2F, d.t,
H†
HCF2†
2
2
2.2.5. Methyl-2-(p-methoxyphenyl)hydrazone- 4,4,5,5,
6,6,6-heptafluoro-2,3-dioxohexanoate (7e) (nc)
CF2, JꢀCF ;CF †ˆ6.6 Hz) ppm. IR: 3380, 1610sh (NH); 1680
2
2
(C=O); 1580, 1500 (C=C, C=N) cm 1. Analysis: Found: C,
49.88; H, 3.27; F, 25.70; N, 9.64. Calc. for C12H11F3N2O4:
C, 49.66; H, 3.47; F, 26.18; N, 9.65%.
1
Yield, 78%; m.p. 81±828C; H-NMR (CDCl3) ꢀ: 3.83
(3H, s, CH3); 3.92 (3H, s, CH3); 7.13 (4H, m, C6H4); 13.60

Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
103
2.2.10. Ethyl-3-phenylhydrazone-5,5,5-trifluoro-2,3,4-
trioxopentanoate (9a) (nc)
Yield, 67%; m.p. 153±1558C; 1H-NMR (CDCl3) ꢀ: 1.36
From chelate 6e (3.41 g, 1.0 mmol) compound 9e (1.37 g,
yield, 40%) was obtained. The physicochemical data were
identical to those listed above.
(3H, t, CH3, J(H±H)ˆ7.1 Hz); 4.40 (2H, q, CH2, J(H±H)
ˆ
7.1 Hz); 7.68 (5H, m, C6H5); 14.80 (1H, br.s, NH) ppm.
19F-NMR (CDCl3) ꢀ: 92.61 (s, CF3) ppm. IR: 3070, 1585
(NH); 1730 (CO2Et), 1695 (CF3CO), 1625 (C=O); 1520
(C=C, C=N) cm 1. Analysis: Found: C, 49.65; H, 3.53; F,
18.51; N, 8.85. Calc. for C12H11F3N2O4: C, 49.38; H, 3.51;
F, 18.02; N, 8.86%.
2.2.15. Ethyl-3-(p-methylphenyl)hydrazone-4-
pentafluorophenyl-2,3,4-trioxobutanoate (9f) (nc)
Yield, 79%; m.p. 148±1498C; 1H-NMR (CDCl3) ꢀ: 1.41
(3H, t, CH3, J(H±H)ˆ7.1 Hz); 2.36 (3H, s, CH3); 4.45 (2H, q,
CH2, J(H±H)ˆ7.1 Hz); 7.15 (5H, m, C6H5); 14.56 (1H, br.s,
NH) ppm. 19F-NMR (CDCl3) ꢀ: 0.92 (2F, m); 11.01 (1F, m);
22.71 (1F, m) ppm. IR: 3090, 1585 (NH); 1735 (CO2Et);
1660 (C6F5CO); 1620 (C=O); 1525, 1510, 1500 (C=C,
C=N) cm 1. Analysis: Found: C, 53.08; H, 2.97; F,
22.17; N, 6.27. Calc. for C19H13F5N2O4: C, 53.28; H,
3.06; F, 22.18; N, 6.54%.
From chelate 6a (2.43 g, 1.0 mmol) compound 9a
(1.52 g, yield, 44%) was obtained. The physicochemical
data were identical to those listed above.
2.2.11. Ethyl-3-(p-methylphenyl)hydrazone-5,5,5
-trifluoro-2,3,4-trioxopentanoate (9b) (nc)
1
Yield, 81%; m.p. 152±1538C; H-NMR ((CD3)2CO) ꢀ:
2.2.16. Ethyl-3-(p-methoxyphenyl)hydrazone-4-
pentafluorophenyl-2,3,4-trioxobutanoate (9g) (nc)
Yield, 84%; m.p. 153±1558C; 1H-NMR (CDCl3) ꢀ: 1.42
1.36 (3H, t, CH3, J(H±H)ˆ7.1 Hz); 2.39 (3H, s, CH3); 4.35
(2H, q, CH2, J(H±H)ˆ7.1 Hz); 7.45 (4H, m, C6H4); 14.51
(1H, br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 92.72
(s, CF3) ppm. IR: 3095, 1590 (NH); 1725 (CO2Et), 1690
(CF3CO), 1625 (C=O); 1525 (C=C, C=N) cm 1. Analysis:
Found: C, 51.15; H, 4.05; F, 17.67; N, 8.35. Calc. for
C14H13F3N2O4: C, 50.92; H, 3.97; F, 17.26; N, 8.48%.
(3H, t, CH3, J(H±H)ˆ7.1 Hz); 4.46 (2H, q, CH2, J(H±H)
ˆ
7.1 Hz); 3.84 (3H, s, OCH3); 7.15 (4H, m, C6H4); 14.80 (1H,
br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 1.10 (2F, m); 11.73
(1F, m); 22.78 (1F, m) ppm. IR: 3080, 1585 (NH); 1730
(CO2Et, C=O); 1665 (C6F5CO); 1530, 1515, 1500 (C=C,
C=N) cm 1. Analysis: Found: C, 51.35; H, 3.00; F, 21.21;
N, 6.34. Calc. for C19H13F5N2O5: C, 51.36; H, 2.95; F,
21.38; N, 6.31%.
2.2.12. Ethyl-3-(p-methoxyphenyl)hydrazone-5,5,5
-trifluoro-2,3,4-trioxopentanoate (9c) (nc)
1
Yield, 69%; m.p. 131±1338C; H-NMR ((CD3)2CO) ꢀ:
1.34 (3H, t, CH3, J(H±H)ˆ7.1 Hz); 3.87 (3H, s, OCH3); 4.39
(2H, q, CH2, J(H±H)ˆ7.1 Hz); 7.40 (4H, m, C6H4); 14.62
(1H, br.s, NH) ppm. 19F-NMR (CDCl3) ꢀ: 92.73 (s,
2.2.17. Methyl-3-phenylhydrazone-4-pentafluorophenyl-
2,3,4-trioxobutanoate (9h) (nc)
Yield, 91%; m.p. 123±1258C; 1H-NMR (CDCl3) ꢀ: 1.45
CF3) ppm. IR: 3090, 1600 (NH); 1730 (CO2Et), 1690
1
(3H, t, CH3, J(H±H)ˆ7.2 Hz); 4.42 (2H, q, CH2, J(H±H)
ˆ
(CF3CO), 1625 (C=O); 1525, 1500 (C=C, C=N) cm
.
7.2 Hz); 7.46 (5H, m, C6H5); 14.80 (1H, br.s, NH) ppm.
19F-NMR (CDCl3) ꢀ: 1.27 (2F, m); 11.33 (1F, m); 22.73 (1F,
m) ppm. IR: 3070, 1590 (NH); 1730 (CO2Et, C=O); 1660
(C6F5CO); 1510, 1500 (C=C, C=N) cm 1. Analysis: Found:
C, 51.25; H, 2.58; F, 23.43; N, 6.79. Calc. for C17H9F5N2O4:
C, 51.01; H, 2.27; F, 23.73; N, 7.00%.
Analysis: Found: C, 48.82; H, 3.71; F, 16.29; N, 8.20. Calc.
for C14H13F3N2O5: C, 48.56; H, 3.78; F, 16.46; N, 8.09%.
2.2.13. Methyl-3-(p-methoxyphenyl)hydrazone-5,5,5-
trifluoro-2,3,4-trioxopentanoate (9d) (nc)
Yield, 71%; m.p. 170±1728C; 1H-NMR (CDCl3) ꢀ: 3.85,
3.96 (6H, s, 2CH3); 7.25 (4H, m, C6H4); 14.80 (1H, br.s,
NH) ppm. 19F-NMR (CDCl3) ꢀ: 90.42 (s, CF3) ppm. IR:
3070, 1590 (NH); 1730 (CO2Et, C=O); 1690 (CF3CO);
1520, 1500 (C=C, C=N) cm 1. Analysis: Found: C,
46.37; H, 3.36; F, 17.15; N, 8.44. Calc. for C12H11F3N2O4:
C, 46.99; H, 3.31; F, 17.17; N, 8.43%.
2.3. Reactions of 2-arylhydrazone-1,2,3-diketo esters with
dinucleophiles
2.3.1. 3-Nonafluorobuthyl-4-(p-methoxyphenyl)
hydrazonepyrazolin-5-one (10) (nc)
A solution of hydrazine hydrate (0.4 g, 8 mmol) in 10 ml
of diethyl ether was added to a solution of compound 7b
(0.47 g, 1 mmol) in 20 ml of diethyl ether. The mixture was
stirred at 208C for 10 min. The solvent was removed.
Recrystallization of residue from hexane gave 10 (0.35 g,
79%) as a yellow powder (m.p. 157±1588C). 1H-NMR
(CD3Cl) ꢀ: 3.85 (3H, s, OCH3); 7.28 (4H, m, C6H4);
9.70, 15.3 (2H, br.s, 2NH) ppm. 19F-NMR (CD3Cl) ꢀ:
36.52 (2F, m, CF2); 38.92 (2F, m, CF2); 49.66 (2F, m,
CF2); 80.92 (3F, m, CF3) ppm. IR: 3260, 1600 (NH);
1660 (C=O); 1590, 1540, 1500 (C=N, C=C) cm 1. Analy-
2.2.14. Ethyl-3-phenylhydrazone-4-pentafluorophenyl-
2,3,4-trioxobutanoate (9e) (nc)
Yield, 91%; m.p. 123±1258C; 1H-NMR (CDCl3) ꢀ: 1.45
(3H, t, CH3, J(H±H)ˆ7.2 Hz); 4.42 (2H, q, CH2, J(H±H)
ˆ
7.2 Hz); 7.46 (5H, m, C6H5); 14.80 (1H, br.s, NH) ppm.
19F-NMR (CDCl3) ꢀ: 1.27 (2F, m); 11.33 (1F, m); 22.73 (1F,
m) ppm. IR: 3070, 1590 (NH); 1730 (CO2Et, C=O); 1660
(C6F5CO); 1510, 1500 (C=C, C=N) cm 1. Analysis: Found:
C, 52.34; H, 2.85; F, 23.01; N, 6.34. Calc. for
C18H11F5N2O4: C, 52.19; H, 2.68; F, 22.93; N, 6.67%.

104
Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
sis: Found: C, 38.40; H, 2.09; F, 39.02; N, 12.76. Calc. for
C14H9F9N4O2: C, 38.55; H, 2.08; F, 39.20; N, 12.84%.
2.4.3. 1-Phenyl-3-tetrafluoroethyl-4-(p-methoxyphenyl)
azo-5-methylpyrazole (13) (nc)
A mixture of compound 8b (0.32 g, 1 mmol), phenylhy-
drazine hydrochloride (0.58 g, 4 mmol) and NaOAc (0.21 g,
2.5 mmol) in 20 ml of methanol was re¯uxed for 2 h. 50 ml
of water was added to the cooling reaction mixture.
The precipitate was ®ltered off and washed with water.
Recrystallization from acetic acid gave 13 (0.32 g, 82%)
2.3.2. 3-Trifluoromethyl-4-(p-methoxyphenyl)
hydrazoneisoxazolin-5-one (11) (nc)
A mixture of compound 7a (0.32 g, 1 mmol), hydroxyl-
amine hydrocloride (0.28 g, 4 mmol) and NaOAc (0.2 g,
2.5 mmol) in 20 ml of methanol was re¯uxed for 3 h. 50 ml
of water was added to the cooling mixture. The resulting
precipitate was ®ltered off, washed with water. Recrystalli-
zation from benzene gave 11 (0.28 g, 80%) as a red powder
(m.p. 140±1418C). 1H-NMR (CDCl3) ꢀ: 3.87 (3H, s,
OCH3); 7.28 (4H, m, C6H4); 13.0 (1H, br.s, 1NH) ppm.
19F-NMR (CDCl3) ꢀ: 96.52 (3F, s, CF3) ppm. IR: 3190,
1590 (NH); 1730, 1720 (C=O); 1550, 1530, 1500 (C=N,
C=C) cm 1. Analysis: Found: C, 46.29; H, 2.79; F, 19.73;
N, 14.68. Calc. for C11H8F3N3O3: C, 46.00; H, 2.81; F,
19.84; N, 14.63%.
1
as a yellow powder (m.p. 115±1168C). H-NMR (CDCl3)
ꢀ: 2.63 (3H, s, CH3); 3.88 (3H, s, OCH3); 6.58 (1H, t.t,
H(CF2)2, J
ˆ53.5, JꢀCF
ˆ5.4 Hz); 7.46 (9H, m,
ꢀH CF2†
HCF2†
2
C6H4, C6H5) ppm. IR: 1590, 1570, 1490 (C=N, CC,
N=N) cm 1. Analysis: Found: C, 58.14; H, 4.17; F,
19.23; N, 14.22. Calc. for C19H16F4N4O: C, 58.16; H,
4.11; F, 19.37; N, 14.28%.
2.4.4. 1-Thiocarbamoyl-3-tetrafluoroethyl-3-hydroxy-4-
(p-methoxyphenyl)azo-5-methylpyrazoline (14) (nc)
A mixture of compound 8b (0.32 g, 1 mmol), thiosemi-
carbazide (0.36 g, 4 mmol) in 20 ml of benzene: DMSO
(3:1) was heated for 50 h. Benzene was removed. 50 ml of
water was added to the residue. The precipitate was ®ltered
off. Recrystallization from chloroform gave 14 (0.33 g,
84%) as a yellow powder (m.p. 125±1268C). 1H-NMR
((CD3)2CO) ꢀ: 2.22 (3H, s, CH3); 3.79 (3H, s, OCH3);
2.4. Reactions of 1,2,3-triketones arylhydrazones with
dinucleophiles
2.4.1. 3-Tetrafluoroethyl-4-(p-methoxyphenyl)azo-5-
methylpyrazole (12a)
6.69 (1H, t.t, H(CF2)2, JꢀH
ˆ51.7, JꢀCF
ˆ6.7 Hz);
CF2†
HCF2†
2
A mixture of compound 8b (0.32 g, 1 mmol), hydrazine
hydrate (0.2 g, 4 mmol) in 10 ml of acetic acid was re¯uxed
for 2.5 h. 50 ml of water was added to the cooled reaction
mixture. The precipitate was ®ltered off, washed with water.
Recrystallization from benzene gave 12a (0.26 g, 83%) as a
yellow powder (m.p. 182±1838C). 1H-NMR (CDCl3) ꢀ: 2.64
(3H, s, CH3); 3.88 (3H, s, OCH3); 6.56 (1H, t.t, H(CF2)2,
6.7 Hz); 7.06 (4H, m, C6H4); 7.9, 8.6, 9.7 (4H, br.s, NH2,
NH, OH) ppm. IR: 3420, 3300, 1600 (NH); 3150 (OH);
1570, 1515, 1500 (C=N, C=C, N=N) cm 1. Analysis:
Found: C, 42.56; H, 3.91; F, 19.58; N, 17.54. Calc. for
C14H15F4N5O2S: C, 42.75; H, 3.84; F, 19.31; N, 17.88%.
2.4.5. Tetrafluoroethyl-3-hydroxy-4-(p-methylpheny)azo-
5-methylisoxazoline (15) (nc)
JꢀH
ˆ53.7, JꢀCF
ˆ6.6 Hz); 7.44 (4H, m, C6H4);
CF2†
HCF2†
2
12.2 (1H, br.s, 1NH) ppm. 19F-NMR (CDCl3) ꢀ: 24.40 (2F,
A mixture of compound 8c (0.32 g, 1 mmol), hydroxyl-
amine hydrocloride (0.28 g, 4 mmol) and NaOAc (0.2 g,
2.5 mmol) in 20 ml of methanol was re¯uxed for 5 h. 50 ml
of water was added to the mixture. The precipitate was
®ltered off. Recrystallization from chloroform gave 15
(0.25 g, 79%) as a yellow powder (m.p. 85±868C).
1H-NMR (CDCl3) ꢀ: 2.09 (3H, s, CH3); 2.31 (3H, s,
d.t, HCF2, JꢀH
ˆ53.7, JꢀCF
ˆ6.6 Hz); 46.25 (2F,
CF2†
HCF2†
HCF2†
2
d.t, CF2, JꢀCF
ˆ6.6 Hz) ppm. IR: 3160, 3080, 1590
2
(NH); 1580, 1500, 1490 (C=N, C=C) cm 1. Analysis:
Found: C, 49.42; H, 3.77; F, 24.17; N, 17.74. Calc. for
C13H12F4N4O: C, 49.41; H, 3.82; F, 24.03; N, 17.71%.
CH3); 6.04 (1H, t.t, H(CF2)2, JꢀH
ˆ52.7, JꢀCF
ˆ
CF2†
HCF2†
2
2.4.2. 3-Tetrafluoroethyl-4-phenylazo-5-methylpyrazole
(12b) (nc)
6.2 Hz); 7.07 (4H, m, C6H4); 9.06 (2H, br.s, NH, OH) ppm.
IR: 3350, 3120, 1600 (NH, OH); 1570, 1520, 1500 (C=N,
C=C, N=N) cm 1. Analysis: Found: C, 48.63; H, 4.33; F,
23.65; N, 12.88. Calc. for C13H13F4N3O2: C, 48.91; H, 4.10;
F, 23.80; N, 13.16%.
A mixture of compound 8d (0.3 g, 1 mmol), hydrazine
hydrate (0.2 g, 4 mmol) in 10 ml of acetic acid was re¯uxed
for 2.5 h. 50 ml of water was added to the cooled reaction
mixture. The precipitate was ®ltered off and washed with
water. Recrystallization from benzene gave 12b (0.23 g,
81%) as a yellow powder (m.p. 180±1818C). 1H-NMR
(CDCl3) ꢀ: 2.65 (3H, s, CH3); 6.54 (1H, t.t, H(CF2)2,
2.5. Heterocyclization of fluorinated 3-arylhydrazone-
1,2,3,4-triketo esters
JꢀH
ˆ53.6, JꢀCF
ˆ5.5 Hz); 7.30 (5H, m, C6H5);
CF2†
HCF2†
2
12.3 (1H, br.s, 1NH) ppm. IR: 3140, 3080, 1570 (NH); 1500,
1490 (C=N, C=C) cm 1. Analysis: Found: C, 50.20; H,
3.33; F, 26.40; N, 19.43. Calc. for C12H10F4N4: C, 50.36; H,
3.52; F, 26.55; N, 19.57%.
2.5.1. 3-Ethoxycarbonyl-4-phenylazo-5-
trifluoromethylpyrazole (16a) (nc)
Hydrazine hydrate (0.2 g, 0.4 mmol) was added to a
solution of compound 9a (0.3 g, 0.1 mmol) in 10 ml of

Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
105
acetic acid. The reaction mixture was re¯uxed for 4 h. 50 ml
of water was added to the cooling mixture. The resulting
precipitate was ®ltered off and washed with water. Repre-
cipitation from chloroform by hexane gave 16a (0.21
g, 67%) as a red powder (m.p. 123±1258C). 1H-NMR
((CD3)2SO) ꢀ: 1.38 (3H, t, CH3, J(H±H)ˆ7.1 Hz); 4.45
(2H, q, CH2, J(H±H)ˆ7.1 Hz); 7.78 (5H, m, C6H5); 11.98
®ltered off. Crystallization from methanol gave 17b (0.2 g,
88%) as an orange powder (m.p. 2808C (decomposition)).
1H-NMR ((CD3)2SO) ꢀ: 7.44 (9H, m, C6H5, C6H4); 11.40,
12.63 (2H, br.s, NH) ppm. 19F-NMR ((CD3)2SO) ꢀ: 1.28
(2F, m); 10.43 (1F, m); 21.70 (2F, m) ppm. IR: 3100, 2710,
1590 (NH); 1685 (C6F5CO); 1660 (C=O); 1535, 1510
(C=N, C=C) cm 1. Analysis: Found: C, 58.02; H, 2.53;
F, 20.74; N, 12.02. Calc. for C22H11F5N4O2: C, 57.65; H,
2.42; F, 20.73; N, 12.22%.
(1H, br.s, NH) ppm. 19F-NMR ((CD3)2SO) ꢀ: 102.3 (s,
1
CF3) ppm. IR: 3300, 3080, 1600 (NH); 1740 (CO2Et) cm
.
Analysis: Found: C, 50.26; H, 3.44; F, 18.04; N, 18,45.
Calc. for C13H11F3N4O2: C, 50.01; H, 3.55; F, 18.25; N,
17.94%.
2.5.5. 1-(p-Methoxyphenyl)-3-ethoxalyl-5,6,7,8-
tetrafluoro-1,4-dihydrocinnolin-4-one (18a) (nc)
Triethylamine (2.78 g, 2.75 mmol) was added to a solu-
tion of compound 9g (2.45 g, 0.55 mmol) in 30 ml of
chloroform. The reaction mixture was re¯uxed for 4 h.
The precipitate of salt was ®ltered off. The ®ltrate
was washed with 10 ml of dilute hydrochloric acid and
water to pHꢁ7. The solvent was removed. The residue was
crystallized from diethyl ether. Recrystallization from iso-
propyl alcohol gave 18a (2.08 g, 89%) as a yellow powder
(m.p. 74±768C). 1H-NMR ((CD3)2SO) ꢀ: 1.26 (3H, t, CH3,
J(H±H)ˆ7.1 Hz); 4.33 (2H, q, CH2, J(H±H)ˆ7.1 Hz); 3.86
(3H, s, OCH3); 7.35 (4H, m, C6H4) ppm. 19F-NMR
((CD3)2SO) ꢀ: 5.23 (1F, m); 17.90 (1F, m); 19.79 (1F,
m); 21.03 (1F, m) ppm. IR: 1740 (CO2Et); 1710 (C=O);
1640 (C=Ocyclo) cm 1. Analysis: Found: C, 53.51; H, 2.86;
F, 18.06; N, 6.28. Calc. for C19H12F4N2O5: C, 53.78; H,
2.85; F, 17.91; N, 6.60%.
2.5.2. 1-Phenyl-3-ethoxycarbonyl-4-(p-methoxyphenyl)
azo-5-trifluoromethylpyrazole (16b) (nc)
Phenylhydrazine (0.12 g, 0.11 mmol) was added to a
solution of compound 9c (0.38 g, 0.11 mmol) in 30 ml of
diethyl ether. The reaction mixture was re¯uxed for 20 h.
The solvent was removed. The residue was washed with
water. Recrystallization from isopropyl alcohol gave 16b
(0.34 g, 74%) as an orange powder (m.p. 114±1168C).
1H-NMR ((CD3)2SO) ꢀ: 1.13 (3H, t, CH3, J(H±H)ˆ5.1 Hz);
4.29 (2H, q, CH2, J(H±H)ˆ5.1 Hz); 3.87 (3H, s, OCH3); 7.48
(5H, m, C6H5); 11.98 (1H, br.s, NH) ppm.
19F-NMR((CD3)2SO) ꢀ: 102.6 (s, CF3) ppm. IR: 1725
(CO2Et); 1595, 1580 (C=N, C=C) cm 1. Analysis: Found:
C, 50.26; H, 3.44; F, 18.04; N, 18,45. Calc. for
C13H11F3N4O2: C, 50.01; H, 3.55; F, 18.25; N, 17.94%.
2.5.6. 1-(p-Methylphenyl)-3-ethoxalyl-5,6,7,8-tetrafluoro-
1,4-dihydrocinnolin-4-one (18b) (nc)
2.5.3. 3-(1-Phenylhydrazone-1,2-di>xo-3,3,3-
trifluoropropyl)-1,2-dihydroquinoxalin-2-one
(17a) (nc)
Triethylamine (1.01 g, 1.0 mmol) was added to a solution
of compound 9h (1.0 g, 0.25 mmol) in 15 ml of chloroform.
The reaction mixture was re¯uxed for 1 h. The precipitate
was ®ltered off. The ®ltrate was washed with 10 ml of dilute
hydrochloric acid and water to pHꢁ7. The solvent was
removed. The residue was crystallized from diethyl ether.
Recrystallization from isopropyl alcohol gave 18b (0.87 g,
93%) as a yellow powder (m.p. 109±1108C). 1H-NMR
((CD3)2CO) ꢀ: 1.30 (3H, t, CH3, J(H±H)ˆ7.3 Hz); 4.35 (2H,
q, CH2, J(H±H)ˆ7.3 Hz); 2.47 (3H, s, CH3); 7.51 (4H, m,
C6H4) ppm. 19F-NMR ((CD3)2CO) ꢀ: 5.02 (1F, m); 17.24
(1F, m); 21.42 (1F, m); 22.55 (1F, m) ppm. IR: 1725
(CO2Et); 1695 (C=O); 1640 (C=Ocyclo) cm 1. Analysis:
Found: C, 55.94; H, 2.95; F, 18.92; N, 6.81. Calc. for
C19H12F4N2O4: C, 55.89; H, 2.96; F, 18.61; N, 6.86%.
A solution of o-phenylenediamine (0.11 g, 0.1 mmol) in
10 ml of methanol was added to a solution of compound 9a
(0.3 g, 0.1 mmol) in 15 ml of methanol. The reaction mix-
ture was re¯uxed for 1 h. The resulting precipitate was
®ltered off. Crystallization from methanol gave 17a
(0.29 g, 85%) as an orange powder (m.p. 170±1728C).
1H-NMR ((CD3)2SO) ꢀ: 7.42 (9H, m, C6H5, C6H4);
11.72, 12.77 (2H, br.s, NH) ppm. 19F-NMR ((CD3)2SO)
ꢀ: 93.23 (s, CF3) ppm. IR: 3090, 2710, 1590 (NH); 1740
1
(CF3CO); 1650 (C=O); 1530, 1510 (C=N, C=C) cm
.
Analysis: Found: C, 56.70; H, 2.98; F, 15.44; N, 15.65.
Calc. for C17H11F3N4O2: C, 56.67; H, 3.08; F, 15.82; N,
15.55%.
2.5.4. 3-(1-Phenylhydrazone-1,2-dioxo-2-
pentafluorophenylethyl)-1,2-dihydroquinoxalin-
2-one (17b) (nc)
2.5.7. 1-Phenyl-3-(1,2-dihydroquinoxalinyl-2-one)-
5,6,7,8-tetrafluoro-1,4-dihydrocinnolin-4-one
(18) (nc)
A solution of o-phenylenediamine (0.21 g, 0.05 mmol) in
15 ml of diethyl ether was added to a solution of compound
9e (0.3 g, 0.1 mmol) in 15 ml of diethyl ether. The reaction
mixture was re¯uxed for 1 h. The resulting precipitate was
Heating of compound 17b (0.2 g, 0.04 mmol) at 280±
2908C for 2 min gave compound 19 (0.19 g, ꢁ100%) as a
white powder (m.p. >3008C). 1H-NMR ((CD3)2SO) ꢀ: 7.43
(9H, m, C6H4, C6H5); 12.74 (1H, br.s, NH) ppm. 19F-NMR

106
Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
((CD3)2SO) ꢀ: 1.91 (1F, m); 15.80 (1F, m); 18.98 (1F,m);
20.0 (1F, m) ppm. IR: 2750, 1635 (NH); 1660 (C=O); 1500,
1490 (C=N, C=C) cm 1. Analysis: Found: C, 59.84; H,
2.29; F, 17.95; N, 12.39. Calc. for C22H10F4N4O4: C, 60.28;
H, 2.38; F, 17.34; N, 12.78%.
It was proved by IR and 1H-NMR spectroscopies that the
obtained compounds 7a±e, 8a±d, 9a±h exist in the hydrazo-
form as their non-¯uorinated analogues [1]. In the 1H-NMR
spectra of products 7a±e, 8a±d, 9a±e the resonance signal of
a methine proton was absent. The IR spectra of 7a±e, 8a±d,
9a±e showed a C=O stretching absorption at 1695±
1
1650 cm from the keto groups of 1,3-dicarbonyl frag-
3. Results and discussion
ment. The low frequency of the C=O stretching absorption is
probably the result of the conjugation of the C=N bond and
participation of the C=O group in an intramolecular hydro-
gen bond with the aminogroup of arylhydrazone fragment.
3.1. Synthesis of fluorinated 2-arylhydrazone-1,2,3-diketo
esters, 2-arylhydrazones of 1,2,3-triketones and 3-
arylhydrazone-1,2,3,4-triketo esters
3.2. Reactions of 2-arylhydrazone-1,3-diketo esters with
dinucleophiles
In present work, it has been found that the ¯uorine-
containing 1,3-keto esters 1a,b, 1,3-diketones 2a,b and
acyl(aroyl)pyruvates 3a±g react with aryldiazonium chlor-
ides in water±methanol medium in presence of NaOAc
to give the corresponding 2-arylhydrazone-1,2,3-diketo
esters 7a±c, 2-arylhydrazones of 1,2,3-triketones 8a±d
and 3-arylhydrazone-1,2,3,4-triketo esters 9a±h (Scheme
1).
For the ®rst time the 1,3-keto esterates of copper (II) 4d,e,
1,3-diketonates of cooper (II) 5a, acyl(aroyl)pyruvates of
copper (II) 6a,e and sodium 6h were used as starting
material in the coupling (Scheme 1). The use of the chelates
forms the corresponding arylhydrazones with good yields,
avoiding decomposition of chelates in the synthesis of free
ligands.
Reaction of the arylhydrazone 7b with hydrazine hydrate
in diethyl ether leads to the substituted pyrazolinone 10.
Compound 7a with hydroxylamine hydrochloride in metha-
nol in the presence of NaOAc gives the substituted iso-
xazolinone 11 (Scheme 2).
Heterocycles 10, 11 may exist in azo- and hydrazoforms.
Compound 10 may exist in amide- and oxyiminoforms also.
The 19F-NMR spectra of 10, 11 have single signals for CF3
or C4F9 groups, indicating the presence of the only tautomer
in each. IR data of compound 10 shows a preference for the
amide form (the absorption band at 1660 cm 1 is typical for
an amide group [15]). In the IR spectra of 10, 11, the low
frequency of the C=O stretching absorption is probably the
Scheme 1.

Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
107
12a,b (Scheme 3). The compounds 12a,b may exist in azo-
and hydrazoforms. The 19F-NMR spectrum of 12a has one
H(CF2)2 group signal, indicating the presence of the only
tautomer. The IR and NMR data could be assigned to either
azo- or hydrazo isomers.
Reaction of 8b with phenylhydrazide hydrochloride in
methanol in the presence of NaOAc yields the correspond-
ing pyrazole 13. Heating 8b with thiosemicarbazide in
DMSO: benzene leads to the substituted pyrazoline 14.
Interaction of 8c with hydroxylamine hydrochloride in
the presence of NaOAc in methanol results in the formation
of isoxazoline 15 (Scheme 3).
Products 14, 15 are stable to dehydration. It is well known
that the formation of hydrated heterocycles in the reactions
with diamines is typical for 2-substituted ¯uorine-contain-
ing 1,3-dicarbonyl compounds [16,17].
Scheme 2.
3.4. Heterocyclization of fluorinated 3-arylhydrazone-
1,3,2,4-triketo esters
result of participation of C=O in an intramolecular hydrogen
bond with the aminogroup, that is possible only in the
hydrazoform.
The arylhydrazones 9a±h were used as precursors for
synthesis of heterocycles. Compound 9a reacts with hydra-
zine hydrate on boiling acetic acid to yield the substituted
pyrazole 16a, unlike the penta¯uorophenylsubstituted ana-
logue 9e. A similar reaction of the latter gives a mixture of
products that is dif®cult to separate. Interaction of 9c with
phenylhydrazine on boiling in diethyl ether for 20 h leads to
pyrazole 16b. Arylhydrazones 9a,e react with o-phenyl-
enediamine on boiling in diethyl ether to give quinoxaline
derivatives 17a,b (Scheme 4).
3.3. Reactions of 1,2,3-triketones arylhydrazones with
dinucleophiles
It was found that arylhydrazones 8b,c react with hydra-
zine hydrate in acetic acid to form the substituted pyrazoles
It is known that the arylhydrazones derived from ben-
zoylacetic esters with o-¯uorines [4,18] undergo intramol-
ecular cyclization through the nucleophilic displacement of
o-¯uorine atom to give the cinnolone structure. We have
found that arylhydrazones of penta¯uorobenzoylpyruvic
ester 9f,g on heating at 1008C in DMSO in presence of
K2CO3 and dibenzo-18-crown-6 or boiling in CHCl3 with an
excess of triethylamine form the substituted cinnolones
18a,b (Scheme 4).
Compound 17b undergoes also intramolecular cycliz-
ation to yield the cinnolone derivative 19. Interestingly,
that compound 19 was also obtained in the reaction of
arylhydrazone 9e with o-phenylenediamine on boiling in
methanol as a by-product. Only under mild conditions (on
boiling in diethyl ether), the formation of 19 was avoided.
Compound 17b completely converted into product 19 with-
out decomposition on heating to ꢁ280 (Scheme 4).
The structures of compounds 18a,b, 19 were assigned on
the basis of their IR, 1H and 19F-NMR spectra. In the
19F-NMR spectra of heterocycles 18a,b, 19, four signals
in the expected ratio were attributed to the ¯uorine atom of
the C6F4 group.
In conclusion, the reactions described demonstrate the
preparation of 2(3)-arylhydrazones of tri- and tetracarbonyl
compounds. Interaction of these arylhydrazones with dinu-
cleophiles is established by the behavior of the correspond-
Scheme 3.

108
Y.V. Burgart et al. / Journal of Fluorine Chemistry 92 (1998) 101±108
Scheme 4.
[10] A.M. Lovelace, D.A. Rausch, M. Postelnek, Aliphatic fluorine-
containing compounds, Inostrannaya literatura, Moscow, 1961, p.
225 (in Russian).
ing di- or tricarbonyl compound and by the nucleophilic
mobility of the o-¯uorine atom of C6F5-substitutent.
[11] V.I. Saloutin, K.I. Pashkevich, I.Ya. Postovsky, Zh. Vses. Khim.
Obsch. 21 (1976) 238.
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