Substituted hydrazonals as building blocks in heterocyclic synthesis: A new route to arylhydrazonocinnolines

Article abstract of DOI:10.3184/030823407X234617

2-heteroylhydrazonopropanals 2a-e and 3-oxo-2-arylhydrazonopropanals 2f-k were prepared via coupling of enaminones 1 with aromatic diazonium salts. Compounds 2a-c condensed with hydrazine hydrate to yield the corresponding hydrazones 3a-c which afford on

Full text of DOI:10.3184/030823407X234617

432 RESEARCH PAPER
JULY, 432–436
JOURNAL OF CHEMICAL RESEARCH 2007
Substituted hydrazonals as building blocks in heterocyclic synthesis:
a new route to arylhydrazonocinnolines
Mariam A. Al-Shiekha, Hanady Y. Medrassia, Mohamed H. Elnagdib and Ebtisam A. Hafezb*
aDepartment of Chemistry, Girls College of Education, Jeddah, P. O. Box 334 Jeddah 21341, Kingdom of Saudi Arabia
bDepartment of Chemistry, Faculty of Science, Cairo University, Giza-12611, Egypt
2-heteroylhydrazonopropanals 2a–e and 3-oxo-2-arylhydrazonopropanals 2f–k were prepared via coupling of
enaminones 1 with aromatic diazonium salts. Compounds 2a–c condensed with hydrazine hydrate to yield the
corresponding hydrazones 3a–c which afford on cyclisation the cinnoline derivatives 6a–c, while condensation of
2g, j with hydrazine hydrate directly yielded the pyrazole derivatives 4g–j. Condensation of 2a–c, f, g with phenyl
hydrazine gave the corresponding phenyl hydrazone derivatives 7a–c, f, g. Structures of 2a, h and 3a were assessed
by single crystal X-ray analyses.
Keywords: 2-arylhydrazonopropanals, enaminones, arylhydrazonopyrazoles, cinnoline
The coupling of enaminones 1 with aromatic diazonium salts
to synthesise 3-oxo-2-aryl or 2-heteroylhydrazonopropanals
2a–k has been previously reported.1,2 The structure and
chemistry of these novel arylhydrazones has attracted much
attention with plenty of uses for these compounds being
reported recently.3,4 It has been noted that in DMSO these
molecules exist as a mixture of two conformers E and Z.2,5
Since 2-arylhydrazonopyrovales undergoes rearrangement
into the 1-arylhydrazono-2-oxopropanes under mild
conditions, we thought that it might be possible that such a
rearrangement might also take place in the case of 2. This
would be a reasonable rationale for the existence of the
equilibrium mixture in the 1H NMR study.
N–N bond also appears as a double bond N=N, rather than a
saturated N–NH bond. It is thus believed that in both structures
2 and 3 the resonance form 2D contributes significantly to
the actual state of the molecules. The dominant anti form
structures of compounds 2 and 3 indicate that in these systems
stereoelectronic factors overweigh possible fixation through
hydrogen bonding (see Scheme 1).
The attempted cyclisation of 3a–c into pyrazoles 4
resulted in the formation of the heteroylhydrazonocinnoline
derivatives 6a–c as indicated by their spectral data, in which
1
the H NMR spectra of compounds 6a–c showed in every
case the existence of hydrazone NH2 at about d 13.5–13.7
ppm. Compounds 6a–c are assumed to be formed via initial
enolisation of 3 to 5 with subsequent cyclisation through
thermally induced 6p electrons.5 The difference in behaviour
between 2a–c and 2g, j is rationalised for in terms decrement
of carbonyl nucleophilicity thus allowing for competiting
electrocyclisation (Scheme 1). Reaction of compounds 2a–c, f,
g with phenylhydrazine afforded the hydrazones 7a–c, f, g. The
attempted cyclisation of 7a–c, f, g into arylhydrazonopyrazoles
4 or heteroylhydrazonocinnoline 6 failed.
Results and discussion
We have prepared the arylhydrazonals 2a–k and obtained
X-ray crystal structures for two of the reaction products,
namely 2a, h; which adopted an anti-form in the solid state.
This agrees with the recent observation that within the 2-
arylhydrazonoketones strereoelectronic factors overweigh any
possible fixation that may occur due to hydrogen bonding.6
Note that the most stable conformation of 2a was found to
be planar, whereas in 2h the phenyl moiety rotates around
a single bond. The planar orientation of the 2a conformer is
probably the result of stereoelectronic interaction between the
oxygen and sulfur lone pairs. We thus believe that assumed
fixation of hydrazones by hydrogen bonding in DMSO
solution is least likely although we observed in almost every
case of aroyl derivatives the presence of two NH signals
integrating for a total of one proton with varying intensity
in each case depending upon the nature of the substituent at
the carbonyl moiety. This may point to the existence of an
equilibrium between the two forms 2C and 2D in DMSO
solution (Scheme 1).
Compounds 2a–c refluxed with hydrazine hydrate in
ethanol for 3 h gave the corresponding hydrazones 3a–c while
compounds 2g, j reacted with hydrazine hydrate under the same
conditions to yield the corresponding arylhydrazonopyrazole
derivatives 4g–j as based upon spectral data.4 Compound 3a
was shown by X-ray crystallography to also adopt the anti-
form 2C where bond lengths and bond angles indicate the
absence of hydrogen bonding (Fig. 3). The observed low
field signal for NH in compounds 2 and 3 is thus a result of
extensive delocalisation of hydrogen NH at both CH and
CO. Selected bond lengths and bond angles for compounds
2a, h and 3a are listed in Tables 1 and 2.7 It is apparent that
as a result of lone pair delocalisation hydrazone nitrogens
have bond angles corresponding to two sp2 nitrogens. The
To conclude, we can state that in 2-oxoarylhydrazones
stereoelectronic effects overweigh any possible fixation that
may be formed through hydrogen bonding. Moreover a novel
cinnoline synthesis is reported.
Crystallographic analysis
The crystals were mounted on glass fibre. All measurements
were performed on an ENRAF NONIUNS FR 590.
The data were collected at a temperature of 20 ± 1°C using
the ω scanning technique to a maximum of 20 of 27.12°.
The structures were solved by the direct method using SIR
92.8 Non-hydrogen atoms were refined anisotropically by
full matrix least squares. Hydrogen atoms were located
geometrically and were refined isotropically.9
Experimental
All melting points were measured on a Gallenkamp electrothermal
melting point apparatus and are uncorrected. IR spectra were recorded
as KBr pellets on a Pye Unicam SP 3-300 Spectrophotometer.
1H NMR spectra were recorded in deuterated dimethylsulfoxide
(DMSO-d6) or deutrated chloroform (CDCl3) at 200, 300 MHz on
a Varian Gemini NMR spectrometer using tetramethylsilane (TMS)
as an internal reference and results are expressed as d values. Mass
spectra were performed on a Shimadzu GCMS-QP 1000 Ex mass
spectrometer at 70 eV. Elemental analyses were carried out at the
Microanalytical centre of Cairo University.
General procedure for preparation of 2-arylhydrazono-3-oxopropanal
derivatives 2a–k:
A cold solution of aryldiazonium salt (10 mmol) prepared by adding
a cold solution of sodium nitrite (10 mmol) in water to a cold
* Correspondent. E-mail: ebtisam_hafez@hotmail.com
PAPER: 07/4616

JOURNAL OF CHEMICAL RESEARCH 2007 433
O
O
O
CHO
O
H
R
O
H
R
R
N
N
N
N
Ar
N
Ar
NH
Ar
2D
2C
2B
O
R
CHO
N
O
CHO
ArN2Cl
R
Me2N
R
O
N
1
H
N
NH
Ar
2
Ar
2a–c,f,g
2A
O
NH2NH2.H2O
2g–j
NH2NHPh
NHPh
R
N
2a–c
N
NH
Ar
O
NH2
HN
N
7a–c,f,g
R
N
R
N
NH
Ar
4g–j
3a–c
N
N
Ar
6a, X =H
b, X = CH3
c, X = Br
S
NH2
N
’
S
HO
X
NH2
N
N
X
N
N
N
5
6
2,3,4,7: a, R = 2-thienyl
b, R = 2-thienyl
Ar = C H
Ar = 4-CH C H
Ar = 4-BrC H
Ar = 4-CH OC H
g, R = 4-CH C H Ar = 4-CH C H
3 6 4 3 6 4
6
5
h, R = 4-CH C H Ar = 4-BrC H
3
6
4
3 6 4 6 4
c, R = 2-thienyl
d, R = 2-thienyl
e, R = 2-thienyl
i, R = 4-CH C H Ar = 4-CH OC H
3 6 4 3 6 4
6
4
j, R = 4-NO C H Ar = 4-BrC H
3
6
4
2 6 4 6 4
Ar = 4-NO C H
k , R = 4-ClC H
Ar = 4-ClC H
6 4
2
6
4
6
4
f , R = 4-CH C H Ar = C H
3
6
4
6 5
Scheme 1
Fig. 1 Thermal ellipsoid plots of the X-ray structure of 2a
(50% probability).
Fig. 2 Thermal ellipsoid plots of the X-ray structure of 2h
(50% probability).
PAPER: 07/4616

434 JOURNAL OF CHEMICAL RESEARCH 2007
Table 1 Crystal data and structure refinement for compounds 2a, h and 3a
2a
2h
3a
CCDC-617779
CCDC-617778
CCDC-629546
Empirical formula
C13H10N2O2S
258.299
Monoclinic
‘C2/c
C16H13BrN2O2
345.19
C13H12N4OS
272.330
Trigonal
‘R-3
Formula weight
Crystal system
Triclinic
‘P-1
Space group
Unit cell parameters
a [Å]
26.0481(8)
5.4763(2)
21.0944(9)
90.00
127.115(2)
90.00
6.5122(2)
7.3253(2)
16.6701(6)
81.1963(13)
81.8713(11)
71.676(2)
742.32(4)
2
36.9986(12)
36.9986(12)
5.2142(2)
90.00
b [Å]
c [Å]
a°
b°
90.00
g°
120.00
6181.4(4)
18
Unit cell volume [Å3]
2399.5(2)
8
Z
R factor
0.053
0.043
0.064
Radiation
MoKá
MoKá
MoKá
1.317
Dx Mg m–3
1.430
1.540
F(000)
1072 loop
0.26
346
2555
Absorption coefficient(mm-1)
Parameters
2.77
0.23
163
190
172
Table 2 Selected bond length [Å] and angles [°] for compounds 2a, h and 3a
Bond lengths 2a Bond lengths 2h
C11 C16
Bond lengths 3a
S1 C18
N2 N4
N2 C7
1.685(3)
1.300(2)
1.319(2)
1.421(3)
1.483(3)
1.467(3)
1.474(3)
1.385(3)
1.476(4)
1.493(4)
1.375(5)
1.388(4)
1.386(4)
1.317(3)
1.314(3)
1.453(3)
C8 C9
N3 H5
C8 C9
N5 C10
C10 C13
N4 C9
N3 C11
N4 N5
1.4.98(3)
1.9082(15)
1.498(3)
1.394(2)
1.392(3)
1.300(2)
1.271(2)
1.324(2)
C11 C12
C18 C20
C12 C18
C12 C14
N2 C16
N2 N6
N4 C6
C7 C8
C7 C15
C8 C13
C11 C16
C16 C17
Bond angles 2a
Bond angles 2h
Bond angles 3a
C13 S1 C18
N4 N2 C7
N2 N4 C6
N4 C6 C9
N2 C7 C8
N2 C7 C15
93.41(14)
119.9(2)
120.9(2)
122.1(2)
117.9(2)
124.0(2)
C18 C20 C19
C12 C18 C20
C11 C16 C17
N2 C16 C11
N6 N2 C16
122.2(3)
120.3(3)
117.7(2)
117.6(2)
121.0(2)
118.9(3)
C7 S1 C17
N6 N3 C11
N4 C9 C11
N4 C5 C10
N5 N4 C9
91.90(10)
118.3(2)
127.5(2)
120.6(2)
117.6(2)
112.1(2)
N6 C4 C15
S1 C17 C16
3-Oxo-2-(phenylhydrazono)3-(thiophen-2-yl)propionaldehyde
(2a): Obtained from ethanol as red crystals. m.p. 115°C (Lit.1 113–
115°C). Yield 85.7%. IR (KBr): n = 3448 (NH), 1643 (CO) cm-1.
1H NMR (DMSO-d6): d 7.22 (m, 1H, H-4thienyl), 7.26–7.68 (m, 5H,
Ar–H), 8.03–8.07 (m, 1H, H-3 and H-5thienyl), 10.0 (s, 1H, CHO) and
14.34 (s, 1H disappeared after D2O exchange, NH) ppm. 13C NMR:
d 118.95, 127.92, 129.59, 136.69 (phenyl carbons) 131.47, 133.51,
137.53, 140.57 (thienoyl carbons), 143.07 (C=N), 182.35 (thienoyl
CO), 189.80 (CHO). MS: m/z 257 (M+–1).
3-Oxo-3-(thiophen-2-yl)2-(p-tolylhydrazono)propionaldehyde
(2b): Obtained from ethanol as yellow crystals. m.p. 134°C (Lit.10
132°C). Yield 82.4%. 1H NMR (DMSO-d6): d 2.35(s, 3H, CH3),
7.29–8.09 (m, 7H, 4H, Ar–H and 3Hthienyl), 10.02 (s, 1H, CHO) and
14.43 (s, 1H, NH). MS: m/z = 272 (M+).
2-[(4-Bromophenyl)hydrazono]-3-oxo-3-(thiophen-2-yl)pro-
pionaldehyde (2c): Obtained from ethanol as yellow powder crystals.
m.p. 162°C. Yield 88%. IR (KBr): n = 3110–3760 (NH), 1640
(CO) cm-1. 1H NMR (DMSO-d6): d 7.25–8.06 (m, 7H, 4H, Ar–H and
3Hthienyl) 9.98 (s, 1H, CHO) and 14.17 (s, 1H, NH). MS: m/z 336
(M+–1). Found: C 46.50; H 2.67; N 8.44. C13H9BrN2O2S (337.19)
requires C 46.31; H 2.69; N 8.31.
2-[(4-Methoxyphenyl)hydrazono]-3-oxo-3-(thiophen-2-yl)pro-
pionaldehyde (2d): Obtained from ethanol as pale orange crystals.
m.p. 249°C. Yield 84.7%. IR (KBr): n = 3108–3751 (NH), 1636 (CO)
cm-1. 1H NMR (DMSO-d6): d 3.78 (s, 3H, OCH3), 7.03–8.08 (m, 7H,
4H, Ar–H and 3Hthienyl), 10.85 (s, 1H, CHO) and 13.49 (s, 1H, NH)
MS: m/z 288 (M+). Found: C 58.25; H 4.19; N 9.69.C14H12N2O3S
(288.32) requires C 58.32; H 4.20; N 9.72.
Fig. 3 Thermal ellipsoid plots of the X-ray structure of 3a
(50% probability).
solution of appropriate arylamine (10 mmol) in conc. HCl-was added
with stirring to a cold solution of appropriate enaminones 1a–d in
ethanol (50 ml) containing sodium acetate (10 mmol). The reaction
mixture was stirred at 0°C for 1 h, then ice cold water was added,
the solid product, so formed was collected and recrystallised from
ethanol.
2-[(4-Nitrophenyl)hydrazono]-3-oxo-3-(thiophen-2-yl)pro-
pionaldehyde (2e): Obtained from ethanol as yellow crystals.
PAPER: 07/4616

JOURNAL OF CHEMICAL RESEARCH 2007 435
m.p. 255°C (Lit.1 256–258). Yield 77%. IR (KBr): n = 3447 (NH),
1652 (CO) cm-1. MS: m/z 302 (M+–1).
4-(4-Bromophenyl)3-(4-Nitrophenylazo)pyrazole (4j): Obtained
from ethanol as yellowish brown crystals. m.p. 244°C. Yield 68%.
IR (KBr): n = 3440 (NH) cm-1. 1H NMR (DMSO-d6): d 7.70–8.32
(m, 8H, Ar–H), 8.38 (s, 1H, pyrazole H-5), 13.84 (s, 1H, NH). MS:
m/z 371 (M+–1). Found: C 48.25; H 2.73; N 18.89 C15H10BrN5O2
(372.18) requires C 48.41; H 2.71; N 18.82.
3-Oxo-2-(phenylhydrazono)3-(p-tolyl)propionaldehyde
(2f):
Obtained from ethanol as red crystals. m.p. 154°C. Yield 88%.
IR (KBr): n = 3112–3755 (NH), 1635 (CO) cm-1. 1H NMR (DMSO-
d6): d. 2.39 (s, 3H, CH3), 7.08–7.85 (m, 9H, Ar–H), 9.53, 9.98 (2 s,
1H, CHO) and 12.01, 14.21 (2 s, 1H, NH) ppm. Z, E isomers. MS: m/z
265 (M+–1). Found C 72.21, H 5.29, N 10.41. C16H14N2O2 (266.29)
requires C 72.16, H 5.30, N 10.52.
General procedure for cyclisation of compounds 3a–c into cinnoline
derivatives 6a–c
3-Oxo-3(p-tolyl)2-(p-tolylhydrazono)propionaldehyde
(2g):
Each of the compounds 3a–c (10 mmol) in pyridine (15 ml) was
refluxed for 4 hours. Then the reaction mixture was left to cool at
room temperature. The solid product, so formed, was collected by
filtration, and then recrystallised from ethanol.
Obtained from ethanol as red crystals. m.p. 165°C. Yield 77.24%.
IR (KBr): n = 3425 (NH) and 1635 (CO) cm-1. 1H NMR (DMSO-d6):
d 2.30 (s, 3H, CH3), 2.36 (s, 3H, CH3), 7.19–7.84 (m, 8H, Ar–H),
9.53, 9.99 (2 s, 1H, CHO) and 12.18, 14.32 (2 s, 1H, NH) ppm, Z,
E isomers. MS: m/z 280 (M+). Found: C 72.75; H 5.77; N 10.09.
C17H16N2O2 (280.32) requires C 72.84; H 5.75; N 9.99.
{[4-(Thiophen-2-yl)cinnolin-3-yl]methylene}hydrazine
(6a):
Obtained from ethanol as reddish-brown crystals. m.p. 205°C. Yield
1
78.32%. IR (KBr): n = 3442 (NH2) cm-1. H NMR (DMSO-d6): d
2-[(4-Bromophenyl)hydrazono]-3-oxo-3(p-tolyl)propionaldehyde
(2h): Obtained from ethanol as orange crystals. m.p. 181°C.
7.25–7.98(m, 7H, 4H, Ar and 3Hthienyl), 8.32 (s, 1H, CH=N), 13.67,
14.02 (2s, 2H, NH2).13C NMR: d 123.90, 128.32, 128.45, 128.63
120.74, 129.52, 154.49 and 130.19, 131.21, 132.18, 177.36 (thienyl
carbons). MS: m/z 254 (M+). Found: C 61.28; H 3.95; N 22.15.
C13H10N4S (254.31) requires C 61.40; H 3.96; N 22.03.
Yield 76.82%. IR (KBr): n = 3417 (NH) and 1635 (CO) cm-1. H
1
NMR (DMSO-d6): d 2.42 (s, 3H, CH3), 7.34–7.85 (m, 8H, Ar–H),
9.55, 9.99 (2s, 1H, CHO) and 11.94, 14.10 (2 s, 1H, NH) ppm. Z,
E isomers. MS: m/z 346 (M++1). Found: C 55.74; H 3.79; N 8.35.
C16H13BrN2O2 (345.19) requires C 55.67; H 3.80; N 8.12.
[6-Methyl-4-(thiophen-2-yl)cinnolin-3-ylmethylene]hydrazine
(6b): Obtained from ethanol as dark brown crystals. m.p. 202°C.
Yield 80.36%. IR (KBr): n = 3448 (NH2)cm-1. 1H NMR (DMSO-d6):
d 2.38 (s, 3H, CH3), 7.20–7.88 (m, 6H, 3H, Ar and 3H thienyl) 8.21 (s,
1H, CH=N), 13.54, 13.89 (2s, 2H, NH2). MS: m/z 268 (M+). Found:
C 62.58; H 4.50; N 20.76 C14H12N4S (268.34) requires C 62.66; H
4.51; N 20.88.
2-[(4-Methoxyphenyl)hydrazono]3-oxo-3(p-tolyl)propionaldehyde
(2i):Obtained from ethanol as orange crystals. m.p. 165°C. Yield
(70.42%). IR (KBr): n = 3440 (NH) and 1645 (CO) cm-1.1H NMR
(DMSO-d6): d 2.38 (s, 3H, CH3), 3.75 (s, 3H, OCH3) 6.73–8.36 (m,
8H, Ar–H), 9.51, 9.99 (2s, 1H, CHO) and 12.21, 14.43 (2s, 1H, NH)
ppm. Z, E isomers. MS: m/z 296 (M+). Found: C, 68.92; H, 5.42; N,
9.50 C17H16N2O3 (296.32): requires C, 68.91; H, 5.44; N, 9.45.
2-[(4-Bromophenyl)hydrazono]-3-(4-nitrophenyl)3-oxo-
propionaldehyde (2j): Obtained from ethanol as pale orange crystals.
m.p. 195°C. Yield 75.86%. IR (KBr): n = 3446 (NH) and 1650 (CO)
cm-1. 1H NMR (DMSO-d6): d 7.60–8.41 (m, 8H, Ar–H), 9.54, 9.96
(2s, 1H, CHO) and 13.82, 14.89 (2s, 1H, NH) ppm, Z, E isomers. MS:
m/z 375 (M+–1). Found: C 47.78; H 2.64; N 11.42. C15H10BrN3O4
(376.16) requires C 47.89; H 2.68; N 11.17.
3-(4-Chlorophenyl)2-](4-Chlorophenyl)hydrazono[-3-oxopro-
pionaldehyde (2k): Obtained from ethanol as orange crystals.
m.p. 165°C. Yield 70.42%. IR (KBr): n = 3423 (NH) and 1648 (CO)
cm-1. 1H NMR (DMSO-d6): d 7.31–7.94 (m, 8H, Ar–H), 9.53, 9.99
(2s, 1H, CHO) and 13.60, 14.07 (2s, 1H, NH) ppm, Z, E isomers.
13C NMR: d 119.07, 129.51, 130.16, 130.59, 132.47, 132.97, 136.29,
137.78 (phenyl carbons) 141.15 (C=N), 188.75 (CO), 190.18 (CHO).
MS: m/z 320 (M+–1). Found: C 56.22; H 3.15; N 8.75.C15H10Cl2N2O2
(321.16) requires C 56.10; H 3.14; N 8.72.
[6-Bromo-4-(thiophen-2-yl)cinnolin-3-ylmethylene]hydrazine(6c):
Obtained from ethanol as reddish brown crystals. m.p. 226°C. Yield
1
78.39%. IR (KBr): n = 3447 (NH2)cm-1. H NMR (DMSO-d6): d
7.18–7.90 (m, 6H, 3H, Ar and 3H thienyl), 8.24 (s, 1H, CH=N), 13.56,
13.90 (2s, 2H, NH2). MS: m/z 332 (M+–1). Found: C 46.74; H 2.70;
N 16.83.C13H9N4BrS (333.21) requires C 46.86; H 2.72; N 16.81.
General procedure for preparation of compounds 7a–c, f, g
A mixture of each compound of 2a–c, f, g (10 mmol) and phenyl
hydrazine (10 mmol) was refluxed for 3 h in ethanol. The solid
product so formed, was collected by filtration, and then recrystallised
from the proper solvents.
2, 3-Bis(phenylhydrazono)1-(thiophen-2-yl) propan-1-one (7a):
Obtained from ethanol/dioxan as orange crystals. m.p. 222°C. Yield
81.78%. IR (KBr): n = 1612 (CO) and 3263, 3417 (NH) cm-1.1H NMR
(DMSO-d6): d 6.89–6.96 (s, 1H, H-4thienyl), 7.10–7.50 (m, 10H,Ar–H),
8.05–8.12 (m, 2H, H-3 and H-5thienyl), 8.40 (s, 1H, HC=N), 11.02 (s,
1H disappear after D2O exchange, NHhydrazone) and 13.47 (s, 1H
disappear after D2O exchange, NHhydrazone). 13C NMR: d 114.07,
117.05, 122.15, 125.23, 129.16, 131.39, 131.67, 133.65 (phenyl
carbons), 134.16, 136.64, 137.80, 140.21 (thienoyl carbons), 144.33
(HC=N), 145.36 (C=N) and 182.13 (thienoyl CO). MS: m/z 348 (M+).
Found: C 65.61; H 4.65; N 16.20. C19H16N4OS (348.43) requires C
65.50; H 4.63; N 16.08.
General procedure for preparation of compounds 3a–c and 4a, b
A mixture of each compound 2a–c, g, j (10 mmol) and hydrazine
hydrate (10 mmol) was refluxed for 3 hours in ethanol. The solid
product so formed, was collected by filtration, then recrystallised
from the proper solvents.
3-Hydrazono-2-phenylhydrazono-1-(thiophen-2-yl)propan-1-one
(3a): Obtained from ethanol as pale orange crystals. m.p. 206°C.
3-Phenylhydrazono-1-(thiophen-2-yl)2-(p-tolylhydrazono)propan-
1-one (7b): Obtained as orange crystals from ethanol/dioxan. m.p.
241°C. Yield 86.45%; IR (KBr): n = 1651 (CO), 3263–3425 (NH)
cm-1. 1H NMR; (DMSO-d6): d 2.30 (s, 3H, CH3), 6.87–8.08 (m,
12H, 9H, Ar–H and 3H thienyl), 8.38 (s, 1H, HC=N), 10.87 (s, 1H,
NHhydrazone) and 13.43 (s, 1H, NHhydrazone).ppm 13C NMR: d 21.14
(CH3), 112.93, 115.97, 120.95, 127.96, 130.23, 130.96, 136.43,
139.32) phenyl carbons), 132.58, 132.75, 133.39, 135.35 (thienoyl
carbons), 140.94 (HC=N), 144.34 (HC=N) and 180.94 (thienoyl CO).
MS: m/z 362 (M+). Found: C 66.32; H 5.10; N 15.51 C20H18N4OS
(362.46) requires C 66.28; H 5.01; N, 15.46.
1
Yield 85.11%. IR (KBr): n = 1612 (CO) and 3733 (NH2) cm-1. H
NMR (DMSO-d6): d 7.04–8.05(m, 10H, 5H, Ar–H, 3Hthienyl and
NH2), 8.21 (s, 1H, HC=N) and 13.78 (s, 1H disappeared after D2O
exchange, NH). MS: m/z 272 (M+). Found: C 57.33; H 4.45; N 20.32.
C13H12N4OS (272.33) requires C 57.34; H 4.44; N 20.57.
3-Hydrazono-1-(thiophen-2-yl)2-(p-tolylhydrazono)propan-1-one
(3b): Obtained from ethanol as red crystals. m.p 261°C. Yield 89.33%
IR (KBr): n = 1612 (CO) and 3393 (NH2) cm-1. 1H NMR (DMSO-d6):
d 2.37 (s, 3H, CH3), 7.20–8.19 (m, 7H, 4H, Ar–H, and 3Hthienyl), 7.51
(s, 2H, NH2), 8.19 (s, 1H, HC=N) and 13.73 (s, 1H, NH). MS: m/z
286 (M+). Found: C 58.66; H 4.92; N 19.60.C14H14N4OS (286.36)
requires C 58.72; H 4.93; N 19.57.
2-](4-Bromophenyl)hydrazono[-3-(phenylhydrazono)1-(thiophen-
2-yl)propan-1-one (7c): Obtained from ethanol/dioxan as orange
crystals, m.p. 255°C. Yield 86%; IR (KBr): n = 1610 (CO), 3258, 3475
(2NH) cm-1. 1H NMR; (DMSO-d6) 6.97–7.76 (m, 12H, 9Haromatic and
3Hthienyl), 8.36 (s, 1H, HC=N), 10.97 (s, 1H, NHhydrazone) and 13.36 (s,
1H, NHhydrazone). MS: m/z 428 (M++1). Found: C, 53.26; H, 3.53; N,
13.05. C19H15BrN4OS (427.32) requires C, 53.40; H, 3.54; N, 13.11.
2, 3-Bis(phenylhydrazono)1-(p-tolyl)propan-1-one (7f): Obtained
from ethanol/dioxan as canary yellow crystals. m.p. 242°C. Yield
2-[(4-Bromophenyl)hydrazono]-3-hydrazono-1-(thiophen-2-yl)
propan-1-one (3c): Obtained from ethanol as orange crystals.
m.p. 205°C. Yield 79.58%. IR (KBr): n = 1653 (CO) and 3392 (NH2)
1
cm-1. H NMR (DMSO-d6): d 7.22–8.00 (m, 9H, 4H, Ar–H, 3Hthienyl
and NH2), 8.15 (s, 1H, HC=N) and 13.75 (s, 1H, NH). MS: m/z 352
(M++1). Found: C, 44.51; H, 3.14; N, 16.01.C13H11BrN4OS (351.22)
requires C, 44.46; H, 3.16; N, 15.95.
1
84.33%. IR (KBr): n = 1628 (CO) and 3260, 3446 (NH) cm-1. H
3-(p-Tolyl)4-(p-tolylazo)pyrazole (4g): Obtained from ethanol
as orange crystals. m.p. 163°C. Yield 79%. IR (KBr): n = 3447
NMR (DMSO-d6): d 2.43 (s, 3H, CH3), 6.91–7.83 (m, 14H, Ar–H),
8.37 (s, 1H, HC=N), 10.94 (s, 1H, NHhydrazone) and 13.35 (s, 1H,
NHhydrazone) ppm. MS: m/z 357 (M++1). Found: C 74.31; H 5.69; N
15.84. C22H20N4O (356.42) requires C 74.14; H 5.66; N 15.72.
3-(Phenylhydrazono)1-p-tolyl-2-(p-tolylhydrazono)propan-1-one
(7g): Obtained from ethanol/dioxan as yellow crystals. m.p. 241°C.
1
(NH) cm1. H NMR (DMSO-d6): d 2.36 (s, 3H, CH3), 2.37 (s, 3H,
CH3), 7.34–7.96 (m, 8H, Ar–H), 8.3 (s, 1H, pyrazole H-5), 13.63
(s, 1H, NH). MS: m/z 276 (M+). Found: C 73.77; H 5.82; N 20.30.
C17H16N4 (276.34) requires C 73.89; H 5.84; N 20.27;
PAPER: 07/4616

436 JOURNAL OF CHEMICAL RESEARCH 2007
Yield 78.75%. IR (KBr): n = 1628 (CO) and 3259, 3447 (NH) cm-1.
1H NMR (DMSO-d6): d 2.33 (s, 3H, CH3), 2.47 (s, 3H, CH3), 6.95–7.0
(m, 13H, Ar–H), 8.42 (s, 1H, HC=N), 10.88 (s, 1H, NHhydrazone) and
13.38 (s, 1H, NHhydrazone) ppm. MS: m/z 370 (M+). Found: C 74.63; H
5.97; N 15.40. C23H22N4O (370.45) requires C 74.57; H 5.99; N 15.12.
3
4
5
R.M. Abdel-Motaleb, A.A. Makhloof, H.M. Ibrahim and M.H. Elnagdi,
J. Het. Chem., 2006, 43, 931.
M.A. Al-Shiekh, A.M. Salaheldin, E.A. Hafez, M.H. Elnagdi, J. Het.
Chem., 2004, 41, 647.
N.A. Al-Awadi, M.H. Elnagdi, Y.A. Ibrahim, K. Kaul and A. Kumar,
Tetrahedron, 2001, 57, 1609.
6
7
I.M. Kenawi and M.H. Elnagdi, Spectrochim. Acta (A), 2006, 805.
CCDC 617778, 617779 and 629546 contain the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via http://www.
ccdc.ac.uk/data_request/cif..
A. Altomare, G. Cascarano, C. Giacorazzo, A. Guaghardi, M.C. Burla,
G. Polidori and M. Camalli, J. Appl. Gryst., 1994, 27, 435.
C.K. Jackson, ORTEP-11, Oak Ridge National Laboratory, Tennessee,
USA, 1976.
Received 21 April 2007; accepted 13 July 2007
Paper 07/4616 doi: 10.3184/030823407X234617
References
8
9
1
F. Al-Omran, M.M. Abdel-Khalik, A.A. El-Khair and M.H. Elnagdi,
Synthesis, 1997, 91.
2
K.M. Al-Zaydi, E.A. Hafez and M.H. Elnagdi, J. Chem. Res. (S), 2000,
154, (M) 2000, 510.
10 S.M. Agamy, J. Chem. Res. (S), 2001, 349, (M) 2001, 901
PAPER: 07/4616