Studies with enaminones: Reactivity of 1,5-disubstituted-1,4-pentadien-3-ones toward electrophilic reagents. A novel route to azolylazines, benzofuranals, pyranones

Article abstract of DOI:10.1002/jhet.5570380422

Several new enaminodienones prepared from substituted acetone and dimethylformamide dimethylacetal were used as precursors for synthesis of pyridines, pyranones and benzofurans.

Full text of DOI:10.1002/jhet.5570380422

Jul-Aug 2001
Studies with Enaminones: Reactivity of 1,5-Disubstituted-
1,4-pentadien-3-ones Toward Electrophilic Reagents.
A Novel Route to Azolylazines, Benzofuranals, Pyranones
949
Saleh Al-Mousawi [a], Mervat Mohammed Abdel-Khalik [b], Seham El-Sherbiny [a],
Elizabeth John [a],Mohammed Hilmy Elnagdi* [a,c]
[a] Department of Chemistry, Faculty of Science, University of Kuwait P. O. Box 5969 Safat, 13060 Kuwait.
[b] Department of Chemistry, Girls College for Arts, Science and Education,
Ain Shams University, P. O. Box 11757 Heliopolis, Cairo, A. R. Egypt
[c] Department of Chemistry, Faculty of Science, Cairo University, Giza, A. R. Egypt
Received March 5, 2001
Several new enaminodienones prepared from substituted acetone and dimethylformamide dimethylacetal
were used as precursors for synthesis of pyridines, pyranones and benzofurans.
J. Heterocyclic Chem., 38, 949 (2001).
Scheme 1
Enaminones are versatile reagents and their chemistry
has recently received considerable interest [1-3]. In recent
work from our laboratories we have successfully utilized
enaminones as building blocks for the synthesis of a wide
range of heterocycles [4-8]. In conjunction with this work
we have investigated possible utility of dienones 1 for syn-
thesis of different otherwise not readily assessable hetero-
aromatic compounds of potential interest, as agrochemical,
pharmaceutical or dye intermediates. In the present article,
we report the synthesis of several new dienones and their
utility as precursor of polyfunctional heteroaromatics. It
has been recently reported [9] that acetone condenses with
dimethylformamide dimethylacetal to yield enaminone 2.
The Attempted condensation of 2 with another molecule of
dimethylformamide dimethylacetal resulted in polymeriza-
tion under reaction conditions. It is most likely that the
methyl function under the reaction conditions has added to
the enaminones moiety in a successive reaction. To avoid
such process we decided to work with substituted acetones.
Consequently, benzotriazol-1-yl-acetone was prepared via
reacting chloroacetone with benzotriazole in basic condi-
tions. Although this reaction has afforded, in the past, mix-
tures of 3 and 4 [10] modification of a procedure recently
published by Katritzky et al., [10-11] enabled exclusive
preparation of 4. Compound 4, so obtained, condensed
readily with dimethylformamide dimethylacetal in reflux-
ing xylene for 10 hours. Although condensation with
dimethylformamide dimethylacetal may in theory lead to a
Condensation of 1-substituted-1-butene-3-one 9a-c with
dimethylformamide dimethylacetal, afforded the dienones
10a-c in good yield. No trace of Z-form is observed, only the
E forms 10a-c were isolated in this reaction as indicated
from the coupling values for olefinic doublets. For example
10c showed two pairs of doublets at δ 5.26 and 7.67 ppm J =
12Hz and at 6.70 and 7.20 ppm J = 16Hz (Scheme 2).
1
mixture of 5 and 6, only 5 is formed in exclusively as H
NMR revealed a presence of a singlet corresponding to
methyl at δ 2.53 ppm and the absence of olefinic doublet of
1
doublet which would be observed in the H NMR spectra
Scheme
2
of 6. Condensing 5 further with one mole of dimethylfor-
mamide dimethylacetal in refluxing xylene afforded the
1
dienaminone 7. The H NMR of this product revealed ben-
zotriazolyl protons in addition to a singlet at δ 7.84 ppm
and two doublets at δ 4.10 and 8.12 ppm for H-4 and H-5.
Although the reaction of 5 with dimethylformamide
1
dimethylacetal may also yield 8 the H NMR indicated that
only the trans form 7 was formed as is confirmed by cou-
pling J values for olefinic doublets (Scheme 1).
Compounds 7 and 10 were then utilized as starting mate-
rials for synthesis of a variety of oxygen and nitrogen

950
S. Al-Mousawi, M. M. Abdel-Khalik, S. El-Sherbiny, E. John, and M. H. Elnagdi
Vol. 38
heteroaromatic. Thus reacting 7 with ammonium
acetate/acetic acid resulted in the formation of benzotria-
zolylpyridone 11a while reaction with hydrazines afforded
the benzotriazolylpyridone 11b,c. Reaction with aminopy-
razole afforded the pyrazolyl benzotriazolylpyridone 12
Compounds 10a-c reacted with p-benzoquinone to yield
a product of addition via dimethylamine and water elimi-
nation, this product can thus be formulated as 18 or iso-
1
meric 20. The H NMR, in all cases, indicated the presence
of a formyl-H at δ 9.0, 9.21 and 9.17 ppm. Thus structure
20a-c was considered most likely. It is thus believed that p-
benzoquinone initially adds to electron rich C-2 yielding
acyclic 19 which then cyclizes exclusively into 20.
Although cyclization into 18 seems to be kinetically more
favored, product 20 is apparently thermodynamically more
stable because of its extended conjugated double bond sys-
tem (Scheme 5).
1
that has been shown via H NMR to exist as equilibrium
mixture of forms 12a and 12b in addition to zwitterionic
form 12c as ring protons for both pyridone and pyrazole
appear as multiplets (Scheme 3). Further attempts to utilize
7 as building blocks for the synthesis of heterocycles via
reaction with active methylene reagents, resulted in the
formation of a complex mixture of products. This can be
readily rationalzied in terms of the existence of multiple
electrophilic sites of nearly equal reactivity, consequently
we shifted our investigation to 10, in which pronounced
difference in reactivity of electrophilic sites is anticipated.
Compounds 10 proved to be a much better building blocks.
Scheme 5
Scheme 3
Compounds 10a-c reacted with hippuric acid 13 in
Compounds 10a,c also reacted with naphthoquinone to
yield the furonaphthofuran derivatives 22a,b (Scheme 6).
acetic anhydride to yield a product assumed to be the pyra-
1
none 16a-c rather than the isomeric 15a-c, based on H
NMR that revealed the existence of NH signal at approxi-
mately 9.60 ppm and absence of proton signal linked to sp
Scheme 6
3
carbon. It is thus assumed that hipuric acid is initially
cyclized into the oxazolone 14 which then adds to the
enaminone moiety at C-1 yielding 15a-c that further
rearrange via loss of water yielding the final isolable pyra-
none 16a-c. This is a new extension to the Kepe acy-
laminopyranone synthesis [9]. Similar reaction of 10a-c
with glycine in acetic anhydride resulted in the formation
of the acetylaminopyranone 16d-f (Scheme 4).
10a,c
Compounds 10a-c reacted with aromatic diazonium salts
1
to yield the hydrazonopentenals 23a-c. The H NMR indi-
cated the presence of a mixture of both E and Z forms of
these pentenals in approximately equivalent ratios as H
1
Scheme 4
NMR revealed two signals at δ 9.57 ppm and 10.14.ppm
for a total of one proton. The low field signal is attributed to
the E formyl-H, which is shifted by deshielding as a result
of H-bonding with the carbonyl oxygen. Trials to cyclize
23a-c into tetrahydropyridazinones failed (Scheme 7).
Scheme 7

Jul-Aug 2001
Studies with Enaminones: Reactivity of 1,5-Disubstituted-1,4-pentadien-3-ones
951
EXPERIMENTAL
1H, J 8Hz, furyl H), 7.20 (d, 1H, J 16Hz, 5-H), 7.67 (d, 1H, J
12Hz, 1-H), 7.76 (d, 1H, J 8Hz, furyl H); MS (EI, 70 EV): m/z
191 [M ].
+
All melting points are uncorrected. IR spectra were recorded in
KBr disks using a Shimadzu IR-470 spectrophotometer. H and
C NMR spectra were recorded on a Bruker Ac-80 spectrometer
Anal. Calcd. for C H NO : C, 69.09; H, 6.85; N, 7.33.
1
11 13
2
Found: C, 68.83; H, 6.74; N, 7.45.
13
with DMSO-d as solvent (unless stated otherwise) and TMS as
6
3-(1,2,3-Benzotriazol-1yl)-1,4-dihydropyridin-4-one (11a).
internal standard; chemical shifts are reported in δ units (ppm).
Mass spectra were measured on GC/MS INCOS XL Finnigan
MAT. Microanalyses were performed on LECO CHNS-932.
Analytical measurements were performed in Cairo University
and Kuwait University.
A mixture of 7 (2.85 g, 10 mmol), ammonium acetate (3.0g)
and acetic acid (0.6 ml) was heated with stirring at 200 °C for
half an hour, then left to cool and triturated with ethanol. The
solid product, so formed, was collected by filtration and crystal-
lized from ethanol to yield 1.27 g of 11a (60%); mp 267 °C; IR
2-(1,2,3-Benzotriazol-1-yl)-1,5-dimethylamino-1,4-pentadiene-
3-one (7).
-1
1
(KBr): ν 3130 (NH), 1646 cm (CO); H NMR (400 MHz,
DMSO): δ 6.48-6.50 (m, 1H, arom. H), 7.43-7.54 (m, 3H, arom.
H), 7.91 (d, 1H, J 8Hz, 5-H), 8.12 (d, 1H, J 8Hz, 6-H), 8.37 (s,
A suspension of 1,2,3-benzotriazol-1-yl-acetone 4 1.75 g (10
mmol) in xylene (30 ml) was treated with dimethylformamide
dimethylacetal 2.38 g (20 mmol). The reaction mixture was
refluxed for 48 hours and was allowed to cool. The solid product,
so formed, was collected by filtration and crystallized from chlo-
roform to yield: 1.54 g of 7 (60%); mp 141 °C; IR (KBr): ν 1599
+
1H, 2-H), 12.30 (s, 1H, NH); MS (EI, 70 EV): m/z 212 [M ].
Anal. Calcd. for C H N O: C, 62.25; H, 3.80; N, 26.40.
11
8 4
Found: C, 61.89; H, 3.94; N, 26.37.
1-Amino-3-(1,2,3-Benzotriazol-1yl)-1,4-dihydropyridin-4-one
(11b).
-1
1
cm (CO); H NMR (400 MHz, DMSO): δ 2.48 (s, 6H, NMe ),
2
To a suspension of 7 (2.85 g, 10 mmol) in ethanol (30 ml),
hydrazine hydrate (1.50 ml) was added. The reaction mixture was
refluxed for 30 minutes then allowed to cool to room tempera-
ture. The solid product, so formed, was collected by filtration and
crystallized from ethanol to yield 11b 1.58 g (70%); mp 221 °C;
2.63 (s, 6H, NMe ), 4.10 (d, 1H, J 12Hz, 4-H), 7.30-7.47 (m, 4H,
2
arom. H), 7.84 (s, 1H, 1-H), 8.12 (d, 1H, J 12Hz, 5-H); MS (EI,
+
70 EV): m/z 285 [M ].
Anal. Calcd. for C H N O: C, 63.14; H, 6.71; N, 24.55.
15 19
5
Found: C, 63.18; H, 6.53; N, 24.32.
-1
1
IR (KBr): ν 3312, 3122 (NH ), 1651 cm (CO); H NMR (400
2
General Procedure for the Preparation of Compounds 10a-c.
MHz, DMSO): δ 6.36-6.55 (m, 3H, arom. H, NH ), 7.40-7.48 (m,
3H, arom. H), 7.80 (d, 1H, J 8Hz, 5-H), 8.02 (d, 1H, J 8Hz, 6-H),
8.26 (s, 1H, 2-H); MS (EI, 70 EV): m/z 227 [M ].
2
A suspension of each of 9a-c (10 mmol) in xylene (30 ml) was
treated with dimethylformamide dimethylacetal 1.19 g (10
mmol). The reaction mixture was refluxed for 3 hours and was
allowed to cool. The solid product, so formed, was collected by
filtration and crystallized from ethanol.
+
Anal. Calcd. for C H N O: C, 58.14; H, 3.99; N, 30.82.
11
9 5
Found: C, 58.14; H, 4.16; N, 30.83.
3-(1,2,3-Benzotriazol-1yl)-1-phenylamino-1,4-dihydropyridin-
4-one (11c).
1-Dimethylamino-5-phenyl-1,4-pentadiene-3-one (10a).
To a suspension of 7 (2.85 g, 10 mmol) in ethanol (30 ml),
phenylhydrazine hydrochloride (1.44 g, 10 mmol) was added.
The reaction mixture was refluxed for 1 hour then allowed to cool
at room temperature. The solid product, so formed, was collected
by filtration and crystallized from ethanol to yield 2.54 g 11c
Compound 10a was obtained in 87% yield (1.27 g) mp 107 °C;
-1
1
IR (KBr): ν 1640 cm (CO); H NMR (400 MHz, DMSO): δ
2.72 (s, 3H, NMe), 2.83 (s, 3H, NMe), 5.38 (d, 1H, J 12Hz, 2-H),
7.03 (d, 1H, J 16Hz, 4-H), 7.32-7.43 (m, 4H; 3H arom. H, 5-H),
7.58-7.76 (m, 2H, arom. H), 7.85 (d, 1H, J 12Hz, 1-H); MS (EI,
-1
1
+
(84%); mp 198 °C; IR (KBr): = 3282 (NH), 1648 cm (CO); H
NMR (400 MHz, DMSO): δ 6.64-7.13 (m, 6H, arom. H), 7.43-
7.56 (m, 3H, arom. H), 8.08-8.10 (m, 2H, arom. H), 8.26 (s, 1H,
70 EV): m/z 201 [M ].
Anal. Calcd. for C H NO: C, 77.58; H, 7.51; N, 6.96. Found:
13 15
C, 77.47; H, 7.39; N, 6.74.
+
2-H), 9.80 (s, 1H, NH); MS (EI, 70 EV): m/z 302 [M -1].
1-Dimethylamino-5-(4-methoxyphenyl)-1,4-pentadiene-3-one
(10b).
Anal. Calcd. for C H N O: C, 67.31; H, 4.32; N, 23.09.
17 13
5
Found: C, 67.11; H, 4.13; N, 22.84.
Compound 10b was obtained in 52% yield (1.20 g) mp 107 °C;
3-(1,2,3-Benzotriazol-1yl)-1-(pyrazol-3yl)-1,4-dihydropyridin-
4-one (12).
-1
1
IR (KBr): ν 1655 cm (CO); H NMR (400 MHz, DMSO): δ
2.82 (s, 3H, NMe), 3.11 (s, 3H, NMe), 3.78 (s, 3H, OMe), 5.24
(d, 1H, J 12Hz, 2-H), 6.85 (d, 1H, J 16Hz, 4-H), 6.95 (d, 2H, J
8Hz, arom. H), 7.34 (d, 1H, J 16Hz, 5-H), 7.60 (d, 2H, J 8Hz,
arom. H), 7.68 (d, 1H, J 12Hz, 1-H); MS (EI, 70 EV): m/z 231
To a suspension of 7 (2.85 g, 10 mmol) in ethanol (30 ml), 3-
aminopyrazole (0.83 g, 10 mmol) was added. The reaction mix-
ture was refluxed for 1 hour then allowed to cool at room temper-
ature. The solid product, so formed, was collected by filtration
and crystallized from pyridine to yield 1.66 g 12 (60%); mp 309
+
[M ].
Anal. Calcd. for C
H NO : C, 72.70; H, 7.41; N, 6.06.
14 17 2
-1
1
°C; IR (KBr): ν 3126 (NH), 1652 cm (CO); H NMR (400
MHz, DMSO): δ 6.63-6.67 (m, 2H, arom. H), 7.44-7.60 (m, 3H,
arom. H), 7.89-7.92 (m, 1H, arom. H), 8.10-8.18 (m, 1H, arom.
H), 8.43-8.56 (m, 1H, arom. H), 8.88-8.91 (m, 1H, arom. H),
Found: C, 72.61; H, 7.39; N, 6.07.
1-Dimethylamino-5-(2-furyl)-1,4-pentadiene-3-one (10c).
Compound 10c was obtained in 80% yield (1.50 g) mp 127 °C;
-1
1
+
IR (KBr): ν 1630 cm (CO); H NMR (400 MHz, DMSO): δ
2.83 (s, 3H, NMe), 3.11 (s, 3H, NMe), 5.26 (d, 1H, J 12Hz, 2-H),
6.58-6.59 (m, 1H, furyl H), 6.70 (d, 1H, J 16Hz, 4-H), 6.77 (d,
13.40 (s, 1H, NH); MS (EI, 70 EV): m/z 278 [M ].
Anal. Calcd. for C H N O: C, 60.42; H, 3.62; N, 30.20.
14 10
6
Found: C, 60.53; H, 3.83; N, 29.92.

952
S. Al-Mousawi, M. M. Abdel-Khalik, S. El-Sherbiny, E. John, and M. H. Elnagdi
Vol. 38
General Procedure for the Preparation of Compounds 16a-c.
N-{6-[(E)-2-(4-Methoxyphenyl)ethenyl]-2-oxo-2H-pyran-3-
yl}acetamide (16e).
A solution of each of 10a-c (10 mmol) and hippuric acid
(1.79g, 10 mmol) in acetic anhydride was heated under reflux for
1 hour. The reaction mixture was concentrated in vacuo. The
solid product obtained upon cooling was isolated by filtration and
recrystallized from an ethanol/dioxane mixture.
Compound 16e was obtained in 72% yield (2.05 g); mp 209
-1
°C; IR (KBr): ν 3329 (NH), 1709 (ring CO), 1678 cm (amide
1
CO); H NMR (400 MHz, DMSO): δ 2.12 (s, 3H, COCH ), 3.80
3
(s, 3H, OCH ), 6.45 (d, 1H, J 8Hz, arom. H), 6.86 (d, 1H, J 16Hz,
3
vinyl-H), 6.95-6.97 (m, 2H, arom. H), 7.13 (d, 1H, J 16Hz, vinyl-
N-{2-Oxo-6-[(E)-2-phenylethenyl]-2H-pyran-3-yl}benzamide
(16a).
H), 7.58-7.60 (m, 2H, arom. H), 8.15-8.17 (m, 1H, arom. H), 9.69
+
(s, 1H, NH); MS (EI, 70 EV): m/z 285 [M ].
Compound 16a was obtained in 62% yield (1.96 g); mp 212
Anal. Calcd. for C
Found: C, 67.34; H, 5.28; N, 4.80.
H NO : C, 67.36; H, 5.30; N, 4.91.
16 15 4
-1
°C; IR (KBr): ν 3343 (NH), 1706 (ring CO), 1670 cm (amide
1
CO); H NMR (400 MHz, DMSO): δ 6.61 (d, 1H, J 8Hz, arom
N-{6-[(E)-2-(2-Furyl)ethenyl]-2-oxo-2H-pyran-3-yl}acetamide
(16f).
H), 7.01 (d, 1H, J 16Hz, vinyl-H), 7.25 (d, 1H, J 16Hz, vinyl-H),
7.34-7.41(m, 3H, arom. H), 7.54-7.56 (m, 2H, arom. H), 7.61-
7.68 (m, 3H, arom. H), 7.94-7.96 (m, 2H, arom. H), 8.16 (d, 1H,
J 8Hz, arom. H), 9.64 (s, 1H, NH); MS (EI, 70 EV): m/z (%) =
Compound 16f was obtained in 86.5% yield (2.12 g); mp 192
-1
°C; IR (KBr): ν 3331 (NH), 1706 (ring CO), 1682 cm (amide
+
1
317 [M ].
CO). H NMR (400 MHz, DMSO): δ 2.12 (s, 3H, COCH ), 6.52-
3
Anal. Calcd. for C
H NO : C, 75.69; H, 4.76; N, 4.41.
20 15 3
6.74 (m, 4H, 2H furyl 4-H, 3-H, pyranyl H, vinyl H), 7.01(d, 1H,
Found: C, 75.59; H, 4.81; N, 4.49.
J 16Hz, vinyl H), 7.76 (s, 1H, furyl H), 8.14 (d, 1H, J 8Hz,
pyranyl H), 9.69 (s, 1H, NH); MS (EI, 70 EV): m/z 245 [M ].
+
N-{6-[(E)-2-(4-Methoxyphenyl)ethenyl]-2-oxo-2H-pyran-3-
yl}benzamide (16b).
Anal. Calcd. for C H NO : C, 63.67; H, 4.52; N, 5.71.
13 11
4
Found: C, 63.35; H, 4.54; N, 5.71.
Compound 16b was obtained in 51% yield (1.76 g); mp 216
General Procedure for the Preparation of Compounds 20a-c and
22a-b.
-1
°C; IR (KBr): ν 3378 (NH), 1702 (ring CO), 1670 cm (amide
1
CO); H NMR (400 MHz, DMSO): δ 3.79 (s, 3H, OCH ), 6.52-
3
6.53 (m, 1H, arom. H), 6.89-6.98 (m, 3H, arom. H, vinyl H), 7.21
(d, 1H, J 16Hz, vinyl-H), 7.52-7.62 (m, 5H, arom. H), 7.94 (d,
2H, J 8Hz, arom. H), 8.12 (d, 1H, J 8Hz, arom. H), 9.57 (s, 1H,
To a stirred solution of each of 10a-c (10 mmol) in acetic acid
50 ml, each of p-benzoquinone and naphthoquinone (10 mmol)
was added. Stirring lasted over night at room temperature. The
reaction mixture was evaporated in vacuo, and the solid product
obtained was isolated by filtration and recrystallized from dioxan.
+
NH); MS (EI, 70 EV): m/z 347 [M ].
Anal. Calcd. for C
H NO : C, 72.61; H, 4.93; N, 4.03.
21 17 4
Found: C, 72.32; H, 4.94; N, 4.11.
2-Phenylethylidene-5-hydroxybenzo[b]furan-3-al (20a).
N-{6-[(E)-2-(2-Furyl)ethenyl]-2-oxo-2H-pyran-3-yl}benzamide
(16c).
Compound 20a was obtained in 59% yield (1.50 g); mp 229
-1
1
°C; IR (KBr): ν 3262 br (OH), 1650 cm (CO); H NMR (400
MHz, DMSO): δ 4.40 (br s, 1H, OH), 6.95-6.98 (m, 1H, arom.
H), 7.45-7.47 (m, 4H, arom. H), 7.71 (d, 1H, J 16Hz, vinyl H),
7.79-7.84 (m, 4H, arom. H, vinyl H), 9.00 (s, 1H, CHO). MS (EI,
Compound 16c was obtained in 73% yield (2.25 g); mp
-1
214 °C; IR (KBr): ν 3370 (NH), 1705 (ring CO), 1676 cm
1
(amide CO). H NMR (400 MHz, DMSO): δ 6.61-6.63 (m, 2H,
+
arom. H), 6.71-6.79 (m, 2H, furyl 4-H, vinyl H), 7.09(d, 1H, J
16Hz, vinyl H), 7.52-7.64 (m, 3H, furyl 3-H, arom. H), 7.79-7.80
(m, 1H, furyl 5-H), 7.93-7.95 (m, 2H, arom. H), 8.11-8.13 (m,
70 EV): m/z 264 [M ].
Anal. Calcd. for C
H O : C, 77.26; H, 4.58. Found: C,
17 12 3
77.40; H, 4.69.
+
1H, arom. H), 9.60 (s, 1H, NH); MS (EI, 70 EV): m/z 307 [M ].
5-Hydroxy-2-(4-methoxyphenylethylidene)benzo[b]furan-3-al
(20b).
Anal. Calcd. for C
H NO : C, 70.35; H, 4.26; N, 4.56.
18 13 4
Found: C, 70.53; H, 4.36; N, 4.70.
Compound 20b was obtained in 86% yield (2.50 g); mp 223
General Procedure for the Preparation of Compounds 16d-f.
-1
1
°C; IR (KBr): ν 3264 br (OH), 1640 cm (CO); H NMR (400
MHz, DMSO): δ 3.82 (s, 3H, OCH ), 6.84-6.86 (m, 1H, arom.
A solution of each of 10a-c (10 mmol) and glycine (0.78 g, 10
mmol) in acetic anhydride was heated under reflux for 1 hour.
The reaction mixture was concentrated in vacuo. The solid prod-
uct obtained upon cooling was isolated by filtration and recrystal-
lized from ethanol.
3
H), 7.03 (d, 2H, J 8Hz, arom. H), 7.50 (d, 1H, J 8Hz, arom. H),
7.59-7.63 (m, 3H, arom. H, vinyl H), 7.82 (d, 2H, J 8Hz, arom.
H), 9.21 (s, 1H, CHO), 9.47 (br s, 1H, OH); MS (EI, 70 EV): m/z
+
294 [M ].
Anal. Calcd. for C
73.20; H, 4.75.
H O : C, 73.46; H, 4.80. Found: C,
18 14 4
N-{2-Oxo-6-[(E)-2-phenylethenyl]-2H-pyran-3-yl}acetamide
(16d).
5-Hydroxy-2-(2-furylethylidene)benzo[b]furan-3-al (20c).
Compound 20c was obtained in 82% yield (2.10 g); mp 230
Compound 16d was obtained in 90% yield (2.30 g); mp 203
-1
°C; IR (KBr): ν 3306 (NH), 1719 (ring CO), 1676 cm (amide
1
-1
1
CO); H NMR (400 MHz, DMSO): δ 2.17 (s, 3H, COCH ), 6.50
°C; IR (KBr): ν 3221 br (OH), 1650 cm (CO); H NMR (400
MHz, DMSO): δ 6.68-6.69 (m, 1H, furyl 4-H), 6.84-6.87 (m, 1H,
furyl 3-H), 7.05 (d, 1H, J 8Hz, arom. H), 7.38 (d, 1H, J 16Hz,
vinyl H), 7.48-7.61 (m, 3H, arom. H, vinyl H), 7.90 (m, 1H, furyl
5-H), 9.17 (s, 1H, CHO), 9.47 (br s, 1H, OH); MS (EI, 70 EV):
3
(d, 1H, J 16Hz, vinyl-H), 6.82-7.73 (m, 7H, arom. H), 8.25 (d,
1H, J 16Hz, vinyl-H), 9.65 (s, 1H, NH). - MS (EI, 70 EV): m/z
255 [M ].
+
Anal. Calcd. for C
H NO : C, 70.58; H, 5.13; N, 5.49.
15 13 3
+
m/z 254 [M ].
Found: C, 70.43; H, 5.16; N, 5.49.

Jul-Aug 2001
Studies with Enaminones: Reactivity of 1,5-Disubstituted-1,4-pentadien-3-ones
953
Anal. Calcd. for C
70.89; H, 4.05.
H
O : C, 70.86; H, 3.96. Found: C,
(400 MHz, DMSO): δ 3.89 (s, 3H, OCH ), 7.02-7.76 (m, 10H,
15 10
4
3
arom. H, vinyl-H), 7.83 (d, 1H, J 16Hz, vinyl H), 9.65 (s, 1H,
+
CHO), 10.16 (s, 1H, NH); MS (EI, 70 EV): m/z 308 [M ].
5-Hydroxy-2-(phenylethylidene)naphtho[1,2-b]furan-3-al (22a).
Compound 22a was obtained in 73% yield (2.30 g); mp 287
°C; IR (KBr): ν 3190 br (OH), 1649 cm (CO); H NMR (400
MHz, DMSO): δ 7.46-7.90 (m, 10H, arom. H, vinyl H), 9.36-
9.42 (m, 2H, arom. H), 9.42 (s, 1H, CHO), 10.32 (br s, 1H, OH);
MS (EI, 70 EV): m/z 314 [M ].
Anal. Calcd. for C
80.24; H, 4.54.
Anal. Calcd. for C H N O : C, 70.11; H, 5.23; N, 9.09.
18 16
2 3
Found: C, 70.02; H, 5.33; N, 8.91.
-1
1
5-(2-Furyl)-3-oxo-2-phenylhydrazono-4-pentene-1-al (23c).
Compound 23c was obtained in 65% yield (1.74 g); mp 129
+
-1
1
°C; IR (KBr): ν 3115 (NH), 1652, 1639 cm (CO); H NMR
(400 MHz, DMSO): δ 6.65-6.68 (m, 1H, furyl-H), 6.96- 6.97 (m,
1H, furyl-H), 7.31-7.34 (m, 1H, furyl-H), 7.51-7.78 (m, 6H,
arom. H, vinyl-H), 7.78 (d, 1H, J 16Hz, vinyl H), 9.57 (s, 1H,
H O : C, 80.24; H, 4.49. Found: C,
21 14 3
5-Hydroxy-2-(fur-2-yl-ethylidene)naphtho[1,2-b]furan-3-al
(22b).
+
CHO), 10.14 (s, 1H, NH); MS (EI, 70 EV): m/z 268 [M ].
Anal. Calcd. for C H N O : C, 67.15; H, 4.51; N, 10.44.
15 12
2 3
Compound 22b was obtained in 56% yield (1.70 g); mp 265
Found: C 66.87; H, 4.73; N, 10.40.
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1
°C; IR (KBr): ν 3201 br (OH), 1650 cm (CO); H NMR (400
MHz, DMSO): δ 6.71-6.72 (m, 1H, furyl 4-H), 7.08 (d, 1H, J
8Hz, arom. H), 7.44 (d, 1H, J 16Hz, vinyl H), 7.57-7.70 (m, 4H,
arom. H, vinyl H, furyl 3-H), 7.93 (d, 1H, J 8Hz, furyl 5-H), 8.20-
8.26 (m, 2H, arom. H), 9.30 (s, 1H, CHO), 10.28 (br s, 1H, OH);
Acknowledgement.
The authors are grateful to University of Kuwait R. A. for
financial support through project Sc 99. Analytical facilities pro-
vided by SAF are highly appreciated.
+
MS (EI, 70 EV): m/z 304 [M ].
Anal. Calcd. for C
74.69; H, 3.91.
H O : C, 74.99; H, 3.97. Found: C,
19 12 4
REFERENCES AND NOTES
General Procedure for the Preparation of Compounds 23a-c.
[1] S. G. Hedge and C. R. Jones, J. Heterocyclic Chem., 30, 1501
(1993).
[2] L. J. O. Figueiredo and C. Kascheres, J. Org. Chem., 62, 1164
(1997).
[3] C. Reidlinger, R. Dworczak, and H. Junek, Monatshefte fur
Chemie, 129, 1207 (1998).
[4] F. Al-Omran, M. M. Abdel-Khalik, A. A. Elkhair and M. H.
Elnagdi, Synthesis, 91 (1997).
A cold solution of benzenediazonium salt (10 mmol) was pre-
pared by adding a solution of sodium nitrite (1.5 g into 10 ml
H O) to a cold solution of aniline hydrochloride with stirring.
2
The resulting solution of the benzenediazonium salt was then
added to a cold solution of each of 10a-c (10 mmol) in ethanol
(50 ml) containing sodium hydroxide.
[5] A. Al-Enezi, B. Al-Saleh, and M. H. Elnagdi, J. Chem. Res.
(S), 4 (1997); ibid (M) 0116 (1997).
3-Oxo-5-phenyl-2-phenylhydrazono-4-pentene-1-al (23a).
Compound 23a was obtained in 80% yield (2.22 g); mp 140
[6] F. Al-Omran, N. Al-Awadhi, A. A. El-Khair, and M. H.
Elnagdi, Org. Prep. Proced. Int., 29, 285 (1997).
[7] F. Al-Omran, N. Al-Awadhi, M. M. Abdel-Khalik, K. Kaul,
A. A. El-Khair, and M. H. Elnagdi, J. Chem. Res. (S) 84 (1997), ibid (M)
0601 (1997).
[8] S. Al-Mousawi, K. S. George, and M. H. Elnagdi, Pharmazie,
54, 571 (1999).
[9] V. Kepe, M. Vocevar, and S. Polanc, J. Heterocyclic Chem.
33, 1707 (1996)
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1
°C; IR (KBr): ν 3118 (NH), 1660, 1641 cm (CO); H NMR
(400 MHz, DMSO): δ 7.47-7.52 (m, 6H, arom. H, vinyl-H), 7.73-
7.75 (m, 5H, arom. H), 7.82 (d, 1H, J 16Hz, vinyl H), 9.69 (s, 1H,
+
CHO), 10.39 (s, 1H, NH); MS (EI, 70 EV): m/z 278 [M ].
Anal. Calcd. for C H N O : C, 73.36; H, 5.07; N, 10.07.
17 14
2 2
Found: C, 73.18; H, 5.10; N, 9.91.
3-Oxo-5-(4-methoxyphenyl)-2-phenylhydrazono-4-pentene-1-al
(23b).
[10] A. R. Katritzky, Xiangfu Lan, Jason Yang, and Olga Denisko,
Chemical Reviews, 98, 409 (1998).
Compound 16a was obtained in 60% yield (1.84 g); mp 152
°C; IR (KBr): ν 3120 (NH), 1658, 1639 cm (CO); H NMR
[11] A. R. Katritzky, S. A.Henderson, and B. Yang, J. Heterocyclic
Chem., 35, 1123 (1998).
-1
1