Studies with 2-Arylhydrazono-3-oxopropanals: A novel route to 4-aroyl-2-aryl-1,2,3-triazoles, 3-substituted 4-arylazopyrazoles, 2-substituted glyoxalonitrile and 3-oxoalkanonitriles

Article abstract of DOI:10.1515/znb-2000-1216

2-Arylhydrazono-3-oxopropanals 1 react with hydroxylamine hydrochloride to yield the corresponding oximes 3 that are cyclized into isoxazoles 9 on reflux in acetic anhydride and are converted into 2-arylhydrazono-3-oxonitriles (4) on treatment with pyridine. The reaction of 1 with hydrazines afforded dihydrazones 10 which were converted to arylazopyrazoles 11 when treated with pyridine, whereas treatment with an acidic reagent resulted in the formation of 3-aroyl-2-phenyl-1,2,3-triazoles 12.

Full text of DOI:10.1515/znb-2000-1216

Studies with 2-Arylhydrazono-3-oxopropanaIs: A Novel Route to
4-Aroyl-2-aryl-l,2,3-triazoIes, 3-Substituted 4-Arylazopyrazoles,
2-Substituted Glyoxalonitrile and 3-Oxoalkanonitriles
Mervat Mohammed Abdel-Khalik3, Samia Michel Agamy3, and
M ohammed Hilmy Elnagdi*b
a Department of Chemistry, Girls College for Arts, Science and Education,
Ain Shams University, Heliopolis, Cairo, A. R. Egypt
b Department of Chemistry, Faculty of Science, Cairo University, Giza, A. R. Egypt
* Reprint requests to Prof. Dr. M. H. Elnagdi.
E-mail: Shelmy@access.com.eg
Z. Naturforsch. 55b, 1211-1215 (2000); received May 23, 2000
Enaminones, 3-Oxo-alkanonitriles, Arylazoazoles
2-Arylhydrazono-3-oxopropanals 1 react with hydroxylamine hydrochloride to yield the
corresponding oximes 3 that are cyclized into isoxazoles 9 on reflux in acetic anhydride and
are converted into 2-arylhydrazono-3-oxonitriles (4) on treatment with pyridine. The reaction
of 1 with hydrazines afforded dihydrazones 10 which were converted to arylazopyrazoles 11
when treated with pyridine, whereas treatment with an acidic reagent resulted in the forma-
tion of 3-aroyl-2-phenyl-l,2,3-triazoles 12.
Although the chemistry of l,2,3-trione-2-arylhy-
drazones has been extensively investigated [1-3],
only little attention has been focussed on the
chemistry of structurally related 2-arylhydrazono-
to cyclize readily into isoxazoles in basic medium,
initial attem pted cyclization of 3a-c in refluxing
pyridine failed and has resulted in the formation
of the 3-oxoalkanonitriles 4a-c. The formation of
4a-c from 3a-c is believed to occur via initial pro-
tonation of the oxime oxygen followed by water
elimination and proton loss facilitated by the
solvent. Alternatively, compounds 4a-c have been
directly obtained from the reaction of la -c with
the reagent system hydroxylamine hydrochloride
in refluxing pyridine. On the other hand, direct
cyclization of 3b to yield the isoxazole 9 can be
achieved upon heating with acetic anhydride.
W hen compound 5 was treated with two moles
of the aryldiazonium salts in ethanol/sodium hy-
droxide, the formazanes 6a, b were obtained pre-
sumably via intermediacy of the bis(arylazo)aldox-
ime 7 which undergoes Japp-Klingmann acyl group
cleavage yielding 8, that dehydrates under the re-
action conditions to give 6.
3-oxopropanals
routes to 2-arylhydrazono-3-oxopropanals
1
[4-5]. The lack of efficient
is
1
probably behind the ignorance of their chemistry.
In earlier work we reported the synthesis of 1 via
coupling the enaminones 2a, b with aromatic dia-
zonium salts and further studies on their utility as
precursors for the preparation of pyridazinones,
pyridazinimines and arylazopyranones [4-6]. In
view of the continued interest in the chemistry of
these compounds, we report here the results of our
investigations aiming to explore the synthetic po-
tential of 1. The present report enables developing
novel routes to 2-arylhydrazono-3-oxonitriles, 2-
aryl-l,2,3-triazoles and of 3-substituted 4-arylazo-
pyrazoles. Thus reacting l a - c with hydroxylamine
hydrochloride in aqueous sodium carbonate af-
forded the aldoximes 3a-c. Compounds 3a-c
were also obtained by an alternative route by cou-
pling the aldoximes 5a-b with one mole equiva-
lent of aryldiazonium salts in ethanol/sodium ace-
tate. Compounds 3a-c can be cyclized to the
isoxazole 9 or converted on the 3-oxoalkanenit-
riles 4a-c by the choice of the appropriate reac-
tion conditions. Although aldoximes are expected
Com pound la reacted with phenylhydrazine
yielding the diphenylhydrazone 10a that could not
be cyclized under a variety of conditions into pyra-
zoles. Similar treatm ent of la, b with hydrazine
hydrate afforded the hydrazone 10b, c which when
refluxed in pyridine afforded the pyrazoles 11a, b.
However refluxing 10b, c in ethanol/hydrochloric
acid resulted in the formation of 1,2,3-triazoles
0932-0776/2000/1200-1211 $06.00 © 2000 Verlag der Zeitschrift für Naturforschung, Tübingen ■www.znaturforsch.com
N
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1212
M. M. Abdel-K halik et al. • Studies with 2-Arylhydrazono-3-Oxopropanals
, ^ XH0
+
R
ArN=NCl
NMe2
'NHAr
NH20H.HC1/
Na2C 03
NH20H.HC1/
Na2C 03
-NAr
Ci?
N
R ^ ^ ^ N O H
NAr
ArHN"
^NO H
^NAr
l,3-4a, R= Ar= Ph
b, R= 2-furyl, Ar = Ph
c, R= 2-füiyL, Ar = 4-CH30-C6H4
-N
.CN
ArHN
^A r
6 a, Ar = Ph
b, Ar = 4-CH30-C 6H4
12a, b that could be also formed from the reaction
of la, b with hydrazine dihydrochloride.
In conclusion 3-oxo-2-arylhydrazonopropanals
are useful starts and their chemistry is different
than the established chemical reactivity pattern of
2-arylhydrazono-l,2,3-triones.
N' NHR
PhN-
pyridine
RN H N H 2
la,b
^NHPh
10a, R1 = R2 = Ph
b, R1 = Ph, R2 = H
c, R1= 2-furyl, R2 = H
H+
11,12a, R =
Ph
b, R = 2-fiiryl
Experimental
NH 2NH2.2HC1
All melting points are uncorrected. IR spectra
were recorded in KBr with a FT IR-820 IPC spec-
trophotom eter Shimadzu (v, cm -1). !H NM R and
13C NMR spectra were recorded on a Varian EM-
390 spectrom eter in [2H 6]DMSO as solvent and
TMS as internal reference; chemical shifts are re-
ported in d units (ppm). Mass spectra were meas-
ured on a Shimadzu GCMS-QP 1000 Ex mass
spectrometer. A t 70 eV. Microanalyses were per-
formed on LECO CHNS-932. Microanalytical
data were obtained from the Microanalytical D ata
Unit at Cairo University.
N
N
N
Ph
12
General procedure for the preparation of 3a-c
A warm solution of hydroxylamine hydrochlo-
ride (0.69 g, 10 mmol) and sodium carbonate (1.27
g, 12 mmol) in 10 ml water were added to a stirred
solution of the arylhydrazonopropanals la -c (10
mmol) in ethanol (4 ml). The reaction mixture was
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M. M. Abdel-Khalik et al. ■Studies with 2-Arylhydrazono-3-Oxopropanals
1213
stirred at room tem perature for one hour. The ox- 3-Phenyl-3-oxo-2-phenylhydrazonopropanitrile
imes soon separated as semisolid crystals that were
solidified by cooling in crushed ice. The solid pro-
duct, so formed, was collected by filtration and
crystallized from ethanol.
(4a):
Yield: 1.66 g (67%); m.p. 134-135 °C.
-
IR
(KBr): v = 3240 (NH), 2210 (CN), 1630 c m '1 (C=
O). - MS (El, 70 EV): m /z (% ) = 249 [M+]. - *H
NM R (300 MHz, DMSO): <5= 7.17-7.96 (m, 10H,
arom. H), 14.23 (s, 1H, NH).
(249.26): calcd. C 72.27, H 4.45, N 16.86; found
C 72.08, H 4.40, N 16.91.
3-Phenyl-3-oxo-2-phenylhydrazonopropanal-l-
oxime (3a):
-
C15H n N30
Yield: 2.13 g (80%); m.p. 202-204 °C.
- IR
(KBr): v = 3240 (OH ), 3210 (NH), 1593 cm "1 (C=
O). - MS (E l, 70 EV): m /z = 249 (M+-18). - *H
NM R (300 MHz, DMSO): Ö = 7.04-7.59 (m, 8H,
arom. H ), 7.81-7.93 (m, 2H, arom. H), 8.45 (s, 1H,
1-H), 11.95 (s, 1H, NH), 12.68 (s, 1H, oxime-H). -
13C{!H} NM R (300 MHz, DMSO): d = 164.02
(CO), 162.58 (C -l), 161.12 (C-2), 152.18, 140.90,
133.14, 127.18, 122.48, 119.30, 115.72, 87.81 (arom.
C). - C 15H 13N302 (267.28): calcd. C 67.40, H 4.90,
N 15.72; found C 67.61, H 4.93, N 15.75.
3-(2-Furyl)-3-oxo-2-phenylhydrazonopropanitrile
(4b):
Yield: 1.69 (71%); m.p. 161-162 °C.
-
IR
(KBr): v = 3245 (NH), 2190 (CN), 1612 cm "1 (C=
O). - MS (El, 70 EV): m /z (% ) = 239 [M+]. - lH
NM R (300 MHz, DM SO): (3 = 6.74-6.75 (m, 1H,
furyl 4-H), 7.14-7.73 (m, 6H, arom. H, furyl 3-
H), 8.26 (s, 1H, furyl 5-H), 11.99 (s, 1H, NH). -
C 13H 9N30 2 (239.23): calcd.
C 65.26, H 3.79,
N 17.57; found C 65.39, H 3.62, N 17.46.
3-(2-Furyl)-3-oxo-2-phenylhydrazonopropanal-l-
oxim e (3b):
3-(2-Furyl)-2-(4-m ethoxyphenylhydrazono)-3-oxo-
propanitrile (4c):
Yield: 2.13 g (83%); m.p. 204-206 °C. - IR
(KBr): v = 3385 (OH), 3145 (NH), 1595 c m '1 (C=
O). - MS (El, 70 EV): m /z (% ) = 239 [M+-18]\ -
lH NM R (300 MHz, DMSO): (3 = 6.74-7.75 (m,
1H, furyl 4-H), 7.10-7.67 (m, 6H, arom. H, furyl
3-H), 8.06-8.12 (m, 1H, furyl 5-H), 8.40 (s, 1H, 1-
H), 11.96 (s, 1H, NH), 12.80 (s, 1H, oxime-H). -
Yield: 1.99 g (74%); m.p. 173-174 °C.
-
IR
(KBr): v = 3209 (NH), 2208 (CN), 1627 cm "1 (C=
O). - MS (El, 70 EV): m /z (% ) = 269 [M+], -
NM R (300 MHz, DMSO): (5 = 3.75 (s, 3H, O CH 3),
6.74-6.75 (m, 1H, furyl 4-H), 7.05 (d, 2H, J = 8
Hz, arom. H), 7.56-7.63 (m, 3H, arom. H, furyl 3-
H), 8.13 (s, 1H, furyl 5-H), 12.32 (s, 1H, NH). -
C 13H 11N30 3 (257.24): calcd.
C
60.69,
H
4.31,
N 16.34; found C 60.89, H 4.36, N 16.23.
C 14H n N30 3 (269.25): calcd.
C 62.45, H 4.12,
3-(2-Furyl)-2-(4-m ethoxyphenylhydrazono)-3-
N 15.61; found C 62.49, H 4.24, N 15.52.
oxopropanal-1 -oxime (3c):
Yield: 2.18 g (76%); m.p. 214-215 °C.
-
IR
General procedure fo r the preparation o f 5a, b:
(KBr): v = 3278 (OH ), 3143 (NH), 1624 dm "1 (C=
O). - MS (El, 70 EV): m /z (% ) - 287 [M+]. - JH
NM R (300 MHz, DMSO): (3 = 3.75 (s, 3H, O CH3),
6.74-6.75 (m, 1H, furyl 4-H), 7.02 (d, 2H, J = 8
Hz, arom. H), 7.25 (d, 2H, J = 8 Hz, arom. H),
7.55-7.57 (m, 1H, furyl 3-H), 8.01-8.03 (m, 1H,
furyl 5-H), 8.39 (s, 1H, 1-H), 12.04 (s, 1H, NH),
12.82 (s, 1H, oxime-H). - C 14H 13N30 4 (287.27):
calcd. C 58.53, H 4.56, N 14.63; found C 58.55,
H 4.49, N 14.74.
Similar reaction condition as for compounds
3 a -c but using the enaminones 2a,b (10 mmol).
The target product 5b was crystallized from etha-
nol as yellow crystals, as for compound 5a it was
obtained as semisolid compound.
3-(2-Furyl)-3-oxo-propanal-l-oxim e (5b):
Yield: 1.16 g (76%); m.p. 123-124 °C.
- IR
(KBr): v = 3304 (O H ), 1665 cm “1 (C = 0). - MS
(El, 70 EV): m /z (% ) = 153 [M+]. - lH NM R (300
MHz, DMSO): (3 = 3.75-3.87 (m, 2H, CH 2), 6.68-
General procedure for the preparation o f 4a-c:
Each of compound 3a-c (10 mmol) was re- 6.75 (m, 1H, furyl 4-H), 6.97-6.99 (m, 1H, furyl
fluxed in pyridine for 1 h, then left to cool at r.t.
The target nitriles separated as yellow crystals that
were collected by filtration and crystallized from
ethanol/dioxane (3:1 v/v).
H-3), 7.47-7.53 (m, 1H, furyl 5-H), 8.00 (s, 1H, 1-
H), 11.15 (s, 1H, oxime-H). - C7H 7N 0 3 (153.13):
calcd. C 54.90, H 4.61, N 9.15; found C 54.98,
H 4.64, N 9.28.
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1214
M. M. Abdel-K halik et al. • Studies with 2-Arylhydrazono-3-Oxopropanals
General procedure fo r the preparation o f 6a, b:
(75%); m.p. 240-242 °C. - IR (KBr): v = 3255
(NH), 1620 c m '1 (C =0). - MS (El, 70 EV): m /z
(% ) = 342 [M+], - *H NM R (300 MHz, DM SO):
Ö = 7.04-7.58 (m, 13H, arom. H), 7.84-7.96 (m,
2H, arom. H), 8.39 (s, 1H, 3-H), 10.87 (s, 1H, NH),
11.68 (s, 1H, NH). - C2iH 18N40 (342.39): calcd.
C 73.66, H 5.30, N 16.36; found C 73.64, H 5.31,
N 16.39.
A cold solution of arenediazonium chloride (30
mmol), prepared as described earlier [1], was
added to a cold solution of each of the oximes 5a, b
(10 mmol) in ethanol (50 ml) containing sodium
acetate (0.60 g). The reaction mixture was stirred
at room tem perature for one hour and the solid
product, so formed, was collected by filtration and
crystallized from ethanol.
General procedure for the preparation o f 10b, c:
2-Phenylhydrazono-2-(phenylazo)acetonitrile (6a):
A mixture of compound la,b (10 mmol) and hy-
drazine monohydrate (0.60 g, 12 mmol) was re-
fluxed in ethanol (10 ml) for 1 h. The solvent was
removed and the residue cooled to deposit a solid,
which was crystallized from ethanol.
Yield: 1.54 g (62%); m.p. 95-97 °C. - IR (KBr):
v = 3230 (NH), 2218 cm “1 (CN). - MS (El, 70
EV). m /z (% ) = 249 [M+], - lH NM R (300 MHz,
DMSO): (5 = 7.02-7.83 (m, 10 H, arom. H), 12.50
(s, 1H, NH). - C14H n N5 (249.27): calcd. C 67.45,
H 4.45, N 28.10; found C 67.26, H 4.42, N 28.30.
3-H ydrazono-l -phenyl-2-phenylhydrazono-l -
propanone (10b):
2-(4-M ethoxyphenylhydrazono)-2-[(4-m ethoxy-
phenyl)azo]acetonitrile (6b):
Yield: 1.97 g (77%); m.p. 240-242 °C. IR (KBr):
v = 3356 and 3220 (NH2), 3220 (NH), 1613 c rrr1
(C = 0). - MS (El, 70 EV): m /z (% ) = 248 [M+-
18]. - !H NMR (300 MHz, DMSO): (5 = 7.09-7.70
(m, 12H, arom. H, N H 2), 8.23 (s, 1H, 3-H), 12.60
Yield: 1.97 g (64%); m.p. 175-176 °C.
- IR
(KBr): v = 3221 (NH), 2219 cm "1 (CN). - MS (El,
70 EV): m /z (% ) = 309 [M+], - XH NM R (300
MHz, DMSO): <5 = 3.80 (s, 3H, O CH 3), 3.84 (s,
3H, O C H 3), 7.08-7.10 (m, 4H, arom. H), 7.77-
(s, 1H, NH).
-
C 15H 14N40 (266.29): calcd.
C 67.65, H 5.30, N 21.04; found C 67.78, H 5.40,
N 20.85.
7.79 (m, 4H, arom. H), 12.44 (s, 1H, NH).
-
C16H 15N50 2 (309.32): calcd. 62.12, 4.89,
C
H
N 22.64; found C 61.97, H 4.87, N 22.76.
l-(2-Furyl)-3-hydrazono-2-phenylhydrazono-l-
propanone (10c):
5-(2-Furyl)-4-(phenylazo)isoxazole (9):
Yield: 1.97 g (77%); m.p. 145-146 °C.
-
IR
Compound 3b (2.57 g, 10 mmol) was refluxed in
acetic anhydride (10 ml) for 1 h, then left to cool
at r.t. The solid product separated as pale yellow
crystals that were collected by filtration and crys-
tallized from ethanol. Yield: 1.60 g (67%); m. p.
159-160 °C. - MS (E l, 70 EV): m /z (% ) = 239
[M+]. - lH NM R (300 MHz, DMSO): d = 6.80-
6.81 (m, 1H, furyl 4-H), 7.19-7.22 (m, 1H, furyl 3-
H), 7.44-7.61 (m, 6H, arom. H, furyl 5-H), 8.12
(s, 1H, isoxazolyl H). - ^C pH } NM R (300 MHz,
DMSO): (3 = 152.94 (C-5), 148.58 (C-3), 146.92 (C-
4), 143.45, 141.89, 140.70, 129.99, 125.58, 121.77,
(KBr): v = 3345 and 3210 (NH2), 3115 (NH), 1593
c m -1 (C =0). - MS (El, 70 EV): m /z (% ) = 238
!H NMR (300 MHz, DMSO): d =
6.69-6.76 (m, 1H, furyl 4-H), 7.03-7.58 (m, 8H,
arom. H, furyl 3-H, N H 2), 7.96-7.98 (m, 1H, furyl
[M+-18].
-
5-H), 8.15 (s, 1H, 3-H), 13.60 (s, 1H, NH).
C13H 12N40 2 (256.26): calcd. 60.93, 4.72,
-
C
H
N 21.87; found C 60.99, H 4.72, N 21.60.
General preparation o f 11a, b:
A
solution of each of compound 10b, c (10
mmol) in pyridine (10 ml) was refluxed for 3 h.
The resultant solution was poured in water. The
solid product obtained was filtered off and crystal-
lized from ethanol.
117.09, 113.10 (arom. carbons).
(239.23): calcd. C 65.26, H 3.79, N 17.57; found C
65.12, H 3.75, N 17.48.
-
C 13H 9N302
1-Phenyl-2,3-bis(phenylhydrazono)-l-propanone
3-Phenyl-4-(phenylazo)pyrazole (11a):
(10a):
Yield: 1.78 g (72%); m.p. 240-242 °C.
-
IR
A mixture of compound la (2.52 g, 10 mmol)
and phenylhydrazine (1.08 g, 10 mmol) was re- (KBr): v = 3220 c ir r 1 (NH). - MS (El, 70 EV):
fluxed in ethanol (10 ml) for 1 h. The solvent was
removed and the residue cooled to deposit a solid,
which was crystallized from ethanol. Yield: 2.56 g
m /z (% ) = 248 [M+],
DMSO): d = 7.09-7.56 (m, 10H, arom. H), 8.65 (s,
1H, 5-H), 12.60 (s, 1H, NH). - C15H 12N4 (248.28):
-
lH NMR (300 MHz,
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M. M. Abdel-Khalik et al. • Studies with 2-Arylhydrazono-3-O xopropanals
1215
calcd. C 72.56, H 4.89, N 22.57; found C 72.39,
H 4.73, N 22.62.
removed and the residue cooled to deposit a solid
which was crystallized from ethanol.
4-Benzoyl-2-phenyl-l,2,3-triazole (12a):
3-(2-Furyl)-4-(phenylazo)pyrazole (11b):
Yield: 1.69 g (68%); m.p. 262-263 °C.
(KBr): v = 1629 cm “1 (C = 0). - MS (El, 70 EV):
m /z (% ) = 249 [M+]. lH NM R (300 MHz,
DMSO): (3 = 7.38-7.59 (m, 8H, arom. H), 7.86-
7.94 (m, 2H, arom. H), 9.14 (s, 1H, H-5).
-
IR
Yield: 1.53 g (69%); m.p. 210-212 °C.
-
IR
(KBr): v = 3215 cm“1 (NH). - MS (EI, 70 EV):
m /z (% ) = 222 [M+]. - !H NM R (300 MHz,
DMSO): (3 = 6.67-6.79 (m, 1H, furyl 4-H), 7.10-
7.84 (m, 6H, arom. H, furyl 3-H), 7.96-7.98 (m,
1H, furyl 5-H), 8.64 (s, 1H, 5-H), 12.60 (s, 1H,
NH). - C13H 10N4 (222.24): calcd. C 70.25, H 4.54,
N 25.21; found C 70.19, H 4.41, N 15.32.
-
-
13C{1H} NM R (300 MHz, DMSO): (3 = 169.45
(CO), 158.63 (C-4), 144.20 (C-5), 142.01, 130.09,
129.69, 128.87, 127.94, 125.18, 116.33, 101.49
(arom. C). - C15H n N30 (249.26): calcd. C 72.27,
H 4.45, N 16.86; found C 72.18, H 4.62, N 16.85.
General procedure for the preparation o f 12a, b:
4-(2-Furyl)-2-phenyl-l,2,3-triazole (12b):
M ethod A: A solution of each of compound
10b,c (10 mmol) in H C l-E tO H (1 m , 10 ml) was
refluxed for 1 h. The resultant solution was left to
cool at r.t. The solid product obtained was filtered
off and crystallized from ethanol. - M ethod B: A
Yield: 1.74 g (73%); m.p. 260-261 °C.
(KBr): v = 1608 c m '1 (C = 0). MS (El, 70 EV):
m /z (% ) = 239 [M-]. !H NM R (300 MHz,
DM SO): (3 = 6.65-6.79 (m, 1H, furyl 4-H), 7.00-
7.62 (m, 6H, arom. H, furyl 3-H), 7.96-7.98 (m,
-
IR
-
mixture of compound la ,b (10 mmol) and hydra- 1H, furyl 5-H), 9.15 (s, 1H, 5-H). - C13H 9N30 2
zine dihydrochloride (1.04 g, 10 mmol) was re- (239.23): calcd. C 65.26, H 3.79, N 17.57; found
fluxed in ethanol (10 ml) for 1 h. The solvent was
C 65.24, H 3.89, N 17.45.
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