Reaction of monocyclic ferrocenyl-4,5-dihydropyrazoles with β-dicarbonyl compounds

Article abstract of DOI:10.1007/s11176-005-0106-4

Monocyclic 3- and 5-ferrocenyl-4,5-dihydropyrazoles with a free NH group in the molecule react with acetylacetone to form the corresponding enaminocarbonyl compounds. The latter were isolated as a single isomer, presumably E. 3-Ferrocenyldihydropyrazoles and 5-ferrocenyl-3-(p-methoxyphenyl)-4,5- dihydropyrazole analogously react with acetoacetic ester. 5-Ferrocenyl-3-phenyl- , 3-(p-bromophenyl)-5-ferrocenyl, and 3,5-diferrocenyl-4,5-dihydropyrazoles react with acetoacetic ester to form acetoacetylpyrazolides. 2004 MAIK Nauka/Interperiodica .

Full text of DOI:10.1007/s11176-005-0106-4

Russian Journal of General Chemistry, Vol. 74, No. 12, 2004, pp. 1830 1835. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004,
pp. 1942 1947.
Original Russian Text Copyright
2004 by E. Klimova, Vazquez Lopez, T. Klimova, Martinez Garcia, Meleshonkova, Ruiz Ramirez.
Reaction of Monocyclic Ferrocenyl-4,5-dihydropyrazoles
with -Dicarbonyl Compounds
E. I. Klimova, E. A. Vazquez Lopez, T. Klimova,
M. Martinez Garcia, N. N. Meleshonkova, and L. Ruiz Ramirez
National Autonomous University of Mexico, Mexico
Institute of Chemistry, National Autonomous University of Mexico, Mexico
Lomonosov Moscow State University, Moscow, Russia
Received January 10, 2003
Abstract Monocyclic 3- and 5-ferrocenyl-4,5-dihydropyrazoles with a free NH group in the molecule
react with acetylacetone to form the corresponding enaminocarbonyl compounds. The latter were isolated as a
single isomer, presumably E. 3-Ferrocenyldihydropyrazoles and 5- ferrocenyl-3-(p-methoxyphenyl)-4,5-di-
hydropyrazole analogously react with acetoacetic ester. 5-Ferrocenyl-3-phenyl-, 3-(p-bromophenyl)-5-ferro-
cenyl, and 3,5-diferrocenyl-4,5-dihydropyrazoles react with acetoacetic ester to form acetoacetylpyrazolides.
The great interest in ferrocenyl-substituted hetero-
cyclic compounds is associated both with the peculiar
chemical behavior of the ferrocene system and with
the unusual properties it imparts to the heterocyclic
fragment. Such compounds exhibit diverse biological
activity and some other important properties [1 9].
Scheme 1.
Fc
Fc C CH=CHAr H NNH
2
2
N
N
H
Ar
O
IIIa IIIc
Ia Ic
Ferrocenyl-substituted 4,5-dihydropyrazoles are
rather well studied [1 9]. They are prepared by
addition of hydrazines to , -unsaturated carbonyl
compounds. A series of stable dihydropyrazoles con-
taining a ferrocenyl substituent and a substituent on
N1 are found to possess biological activity. In detail,
4-acetyl-3-ferrocenyl-1,4,5-triazatricyclo[5.2.2.02.6]-
undec-5-ene exhibits a high antiviral activity [9].
Introduction in ferrocenyl-4,5-dihydropyrazole of ad-
ditional carbo- and heterocyclic fragments, as well as
various substituents on the N1 atom of the pyrazole
ring permits one to expect a broader spectrum of
useful properties in the resulting products.
Ar = Ph (a), p-CH3OC6H4 (b), p-BrC6H4 (c); Fc =
C5H5FeC5H4.
Ar
Ar C CH=CHFc H NNH
2
2
N
N
H
Fc
O
IVa IVd
IIa IId
Ar = Ph (a), p-CH3OC6H4 (b), p-BrC6H4 (c), Fc (d).
derivatives Va Vc and VIa VId, respectively
(Scheme 2).
In the present work we have studied the reaction
of monocyclic ferrocenyldihydropyrazoles with -di-
carbonyl compounds, such as acetylacetone and aceto-
acetic ester. Starting dihydropyrazoles Ia Ic and IIa
IId were prepared by a standard procedure from cor-
responding , -unsaturated ketones IIIa IIIc and
IVa IVd and hydrazine hydrate [4, 6, 9] (Scheme 1).
Conclusive evidence for the structure of the result-
ing compounds was obtained from their H and 13C
1
NMR spectra and elemental analyses (see Experi-
mental).
1
The H NMR spectra of products Va Vc and VIa
VId contain an ABX proton system characteristic of
dihydropyrazoles and vary significantly depending on
the position of the ferrocenyl substituent in the hetero-
ring. In 3-ferrocenyldihydropyrazoles Va Vc, the
It was found that ferrocenyl-4,5-dihydropyrazoles
Ia Ic and IIa IId react with acetylacetone under
short reflux (about 5 min) to give enaminocarbonyl
1070-3632/04/7412-1830 2004 MAIK Nauka/Interperiodica

REACTION OF MONOCYCLIC FERROCENYL-4,5-DIHYDROPYRAZOLES
1831
Scheme 2.
usly react with acetoacetic ester to give compounds
VIIa VIIc (Scheme 3).
Fc
Scheme 3.
N
N
C
Ar
Fc
CH3COCH2COOC2H5
H
Ia Ic
Ia Ic
C
H3C
N
CH3COCH2COCH3
COCH3
N
C
Ar
Va Vc
IIa IId
H
C
Ar
H3C
COOC2H5
VIIa VIIc
N
N
C
Fc
The structure of products VIIa VIIc was proved
H
by means of H and 13C NMR spectra (Tables 1 and
1
C
H3C
COCH3
VIa VId
2) which contain well-defined signals of the ABX
system of the dihydropyrazoline ring, a triplet and a
singlet of two methyl groups, as well as a singlet of
the olefin proton. The H and 13C NMR spectra of
1
geminal HA and HB proton signals appear at 2.88
3.71 ppm ( 0.74 0.82 ppm). Therewith, the olefin
proton signals of the substituent on N1 have a slightly
different chemical shift than those of HX ( 5.14
5.18 and 5.20 5.24 ppm). Contrary to that, in 5-ferro-
cenyldihydropyrazoles VIa c, one of the methylene
proton signals is shifted noticeably downfield (
compounds VIIa VIIc have common characteristics
with those of compounds Va Vc, but the olefin
proton singlet of dihydropyrazoles VIIa VIIc is
4.40 4.70 ppm) from the re-
spective signal of compounds Va Vc.
located upfield (
Unlike what is observed with dihydropyrazoles Ia
Ic, compound IIb is the only of pyrazolines IIa IId,
whose reaction with acetoacetic ester provides an
enaminocarbonyl derivative (compound VIIIb). The
other 5-ferrocenyl-4,5-dihydropyrazolines IIa, IIc,
and IId react with acetoacetic acid under a more pro-
longed heating to give acetoacetic pyrazolides VIIIa,
VIIIc, and VIIId, respectively (Scheme 4).
3.65 3.70 ppm),
0.01 0.09 ppm, and the olefin
proton signals ( 5.46 ppm) are located downfield
from the heteroring HX proton signals ( 5.20 ppm).
In the presence of two ferrocenyl substituents in the 3
and 5 positions of the heteroring (compound VId), the
chemical shifts of heteroring and olefin protons are
close to those in 5-ferrocenyl derivatives VIa VIc.
Position of the ferrocenyl group in 1-(1-methyl-3-
Scheme 4.
oxopent-2-en-1-yl)-4,5-dihydropyrazoles
influences
chemical shifts of its protons. Hence, in 3-ferrocenyl
derivatives Va Vc, all proton signals of the substituted
ferrocene cyclopentadienyl ring are located downfield
from the signal of the unsubstituted cyclopentadienyl
ring. In 5-ferrocenyldihydropyrazoles VIa VIc con-
taining the ferrocenyl substituent on an sp3 carbon
atom, part of the signals of the substituted cyclopenta-
dienyl ring are located upfield from the C5H5 proton
signal.
OCH3
N
N
C
Fc
H
C
IIa IIdCH COCH COOC H
H3C
3
2
2 5
COOC2H5
VIIIb
Ar
Further evidence for the structure of enaminocar-
bonyl dihydropyrazole derivatives Va Vc and VIa
VId was provided by the observation in the 13C NMR
spectra of expected number of signals of quaternary,
as well as methyl, methylene, methine, aryl, and fer-
rocenyl carbon atoms. A significant specific feature
of the 13C NMR spectra of compounds Va Vc is that
the CipsoFc carbon signals are observed upfield (
75.0 ppm) compared with the respective signals of
N
N
Fc
C
O
CH2
COCH3
VIIIa,VIIIc, VIIId
1
The H NMR spectra of pyrazolides VIIIa, VIIIc,
and VIIId have preserved the pyrazoline ABX proton
system. They lack the singlet of the olefin proton and
the triplet of the ethoxyethyl methyl protons and
dihydropyrazoles VIa VIc (
89.0 ppm).
Further we found that pyrazolines Ia Ic analogo-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 12 2004

1832
KLIMOVA et al.
1
Table 1. H NMR spectra of compounds IIa, IIc, IId, Va Vc, VIa VId, VIIa VIIc, and VIIIa VIIId, , ppm (J, Hz)
Comp.
no.
C5H5, s
C5H4, m
CH3, CH2
CH, NH
Ar
IIa
4.20 (5H) 4.13 (4H)
4.20 (5H) 4.14 (4H)
3.05 d.d (1H, J 5.4, 16.2), 3.33 d.d 4.66 d.d (1H, J 5.4, 10.2), 6.92 d (2H,
(1H, J 10.2, 16.2)
5.84 br.s (1H)
J 8.7), 7.49 d
(2H, J 8.7)
IIc
3.00 d.d (1H, J 5.7, 16.2), 3.31 d.d 4.67 d.d (1H, J 5.7, 10.5), 7.48 d (2H,
(1H, J 10.5, 16.2)
5.87 br.s (1H)
J 9.0), 7.52 d
(2H, J 9.0)
IId
Va
4.13 (5H) 4.16 (4H),
4.21 (5H) 4.31 (2H),
4.56 (2H)
4.07 (5H) 4.39 (2H),
4.50 (1H),
2.84 d.d (1H, J 3.9, 15.9), 3.22 d.d 4.52 d.d (1H, J 3.9, 10.5),
(1H, J 10.5, 15.9) 5.61 br.s (1H)
1.97 s (3H), 2.67 s (3H), 2.96 d.d (1H, 5.18 br.s (1H), 5.20 d.d 7.15 7.42 (5H)
J 3.9, 17.1), 3.71 d.d (1H, J 11.4, 17.1) (1H, J 3.9, 11.4)
4.68 (1H)
Vb
4.08 (5H) 4.38 (2H),
4.50 (1H),
1.98 s (3H), 2.66 s (3H), 2.94 d.d (1H, 5.21 br.s (1H), 5.23 d.d 6.90 d (2H,
J 3.6, 17.1), 3.68 d.d (1H, J 11.4, 17.1), (1H, J 3.6, 11.4)
9.0), 7.11 d
4.68 (1H)
3.79 s (3H)
(2H, J 9.0)
Vc
4.08 (5H) 4.40 (2H),
4.52 (1H),
1.98 s (3H), 2.67 s (3H), 2.92 d.d (1H, 5.15 br.s (1H), 5.22 d.d 7.07 d (2H,
J 3.9, 17.1), 3.72 d.d (1H, J 11.4, 17.1) (1H, J 3.9, 11.4)
J 8.2), 7.51 d
(2H, J 8.2)
4.65 (1H)
VIa
VIb
VIc
VId
4.12 (5H) 4.08 (1H),
4.17 (1H),
4.21 (2H)
4.12 (5H) 4.08 (1H),
4.16 (1H),
4.20 (2H)
4.12 (5H) 4.06 (1H),
4.18 (1H),
2.10 s (3H), 2.72 s (3H), 3.75 d.d (1H, 5.11 d.d (1H, J 6.3, 8.4), 7.43 m (3H),
J 6.3, 17.1), 3.78 d.d (1H, J 8.4, 17.1)
5.46 s (1H)
7.83 m (2H)
J 8.2)
2.09 s (3H), 2.71 s (3H), 3.72 d.d (1H,
5.09 d.d (1H, J 6.0, 8.6), 6.97 d (2H,
J 6.0, 11.4), 3.76 d.d (1H, J 8.6, 11.4), 5.43 s (1H)
3.78 s (3H)
J 9.0), 7.76 d
(2H, J 9.0)
2.10 s (3H), 2.70 s (3H), 3.70 d.d (1H, 5.12 d.d (1H, J 5.4, 9.6), 7.57 d (2H, J
J 5.4, 17.1), 3.74 d.d (1H, J 9.6, 17.1) 5.46 s (1H)
9.0), 7.67 d (2H,
4.21 (2H)
J 9.0)
4.16 (5H), 4.08 (1H),
4.21 (5H) 4.23 (3H),
4.44 (2H),
2.10 s (3H), 2.66 s (3H), 3.49 d.d (1H, 5.06 d.d (1H, J 6.9, 10.5),
J 6.9, 16.8), 3.67 d.d (1H, J 10.5, 16.8) 5.44 s (1H)
4.61 (1H),
4.74 (1H)
VIIa
VIIb
VIIc
4.05 (5H) 4.36 (2H),
4.47 (1H),
4.65 (1H)
4.07 (5H) 4.36 (2H),
4.48 (1H),
4.65 (1H)
4.07 (5H) 4.37 (2H),
4.49 (1H),
1.20 t (3H, J 6.7), 2.64 s (3H), 2.91 d.d 4.77 br.s (1H), 5.24 d.d 7.17 7.36 m
(1H, J 3.9, 16.5), 3.68 d.d (1H, J 11.7,
16.5), 4.00 q (2H, J 6.7)
(1H, J 3.9, 11.7)
(5H)
1.21 t (3H, J 6.9), 2.63 s (3H), 2.90 d.d 4.77 br.s (1H), 5.20 d.d
(1H, J 3.8, 17.0), 3.67 d.d (1H, J 11.4, (1H, J 3.8, 11.4)
17.0), 3.78 s (3H), 4.01 q (2H, J 6.9)
1.21 t (3H, J 7.2), 2.64 s (3H), 2.88 d.d 4.67 br.s (1H), 5.19 d.d
(1H, J 3.9, 17.1), 3.70 d.d (1H, J 12.0, (1H, J 3.9, 12.0)
17.1), 4.02 q (2H, J 7.2)
6.88 d (2H,
J 8.7), 7.11 d
(2H, J 8.7)
7.07 d (2H,
J 8.4), 7.50 d
J 8.4)
4.63 (1H)
VIIIa 4.15 (5H) 4.03 (1H),
4.13 (1H),
2.21 s (3H), 3.56 d.d (1H, J 4.2, 17.4), 5.52 d.d (1H, J 4.2, 10.8) 7.47 m (3H),
3.72 d.d (1H, J 10.8, 17.4), 3.75 d (1H,
J 16.9), 3.85 d (1H, J 16.9)
7.76 m (2H)
4.18 (1H),
4.48 (1H)
VIIIb 4.12 (5H) 4.07 (1H),
4.09 (1H),
1.25 t (3H, J 6.9), 2.67 s (3H), 3.65 d.d 4.98 s (1H), 5.06 d.d (1H, 6.97 d (2H,
(1H, J 4.5, 16.8), 3.74 d.d (1H, J 10.4, J 4.5, 10.4)
16.8), 3.86 s (3H), 4.18 q (2H, J 6.9)
J 8.4), 7.73 d
(2H, J 8.4)
4.14 (1H),
4.22 (1H)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 12 2004

REACTION OF MONOCYCLIC FERROCENYL-4,5-DIHYDROPYRAZOLES
Table 1. (Contd.)
1833
Comp.
no.
C5H5, s
C5H4, m
CH3, CH2
CH,
NH
Ar
VIIIc 4.14 (5H) 4.01 (1H),
4.13 (1H),
2.21 s (3H), 3.52 d.d (1H, J 3.9, 17.4),
3.69 d.d (1H, J 11.1, 17.4), 3.75 d (1H,
J 15.9), 3.86 d (1H, J 15.9)
5.53 d.d (1H, J 3.9, 11.1) 7.57 d (2H,
J 9.0), 7.63 d
(2H, J 9.0)
4.18 (1H),
4.47 (1H)
VIIId 4.18 (5H), 4.02 (1H),
4.21 (5H) 4.15 (1H),
4.23 (2H),
2.37 s (3H), 3.36 d.d (1H, J 3.9, 17.1),
3.62 d.d (1H, J 11.1, 17.1), 3.64 d (1H,
J 15.6), 3.86 d (1H, J 15.6)
5.47 d.d (1H, J 3.9, 11.1)
4.45 (2H),
4.49 (1H),
4.68 (1H)
Table 2. 13C NMR spectra of compounds Va Vc, VIa VId, VIIa VIIc, VIIIa, and VIIIb (75 MHz), , ppm
Comp.
no.
C5H5
C5H4
CipsoFc
CH2, CH3
C
CH=
CH C=O
Ar
Va
68.3 67.0, 67.6, 70.3,
70.5
69.3 67.0, 67.5, 70.3,
70.4
69.3 67.0, 67.5, 70.4,
70.5
68.7 66.6, 67.8, 68.3,
68.4
68.5 66.5, 67.8, 67.9,
68.8
68.8 66.5, 67.9, 68.4,
68.5
68.8, 66.2, 67.2, 67.6,
69.5 67.7, 68.4, 68.7,
70.2, 70.5
75.5
75.6
75.2
88.5
91.7
88.4
16.3, 31.8,
44.5
16.3, 31.8,
44.6, 55.3
16.3, 31.8, 44.4 121.8, 140.0,
154.4
16.4, 32.0, 41.4 131.6, 152.7,
155.8
16.8, 31.8,
46.2, 55.5
19.0, 20.5,
23.4, 24.2
141.0, 154.6,
155.0
133.1, 154.6,
155.1, 159.2
96.8
96.7
96.9
97.6
100.4
98.1
96.4
62.1 195.5 124.9, 128.0,
129.2
61.7 195.5 114.6, 126.2
Vb
Vc
61.5 195.5 126.7, 132.4
VIa
VIb
VIc
VId
57.7 195.5 126.3, 128.8,
129.9
65.9 191.1 113.7, 130.5
118.8, 129.9,
145.7, 163.7
124.2, 130.6,
151.4, 155.6
57.9 195.7 127.7, 132.1
57.2 195.2
75.7, 16.6, 31.9, 43.4 155.0, 155.7
88.8
VIIa
VIIb
VIIc
VIIIa
69.2 67.4, 68.8, 70.0,
70.2
69.3 66.8, 67.4, 70.0,
70.2
69.3 66.9, 67.3, 70.2,
70.3
68.6 65.5, 68.3, 68.4,
70.1
75.9
76.1
75.7
86.8
88.8
14.6, 15.9,
44.6, 55.3, 58.4 155.4
14.6, 15.9, 44.7, 133.4, 152.8,
55.3, 58.5
14.6, 15.9, 44.5, 121.7, 140.2,
58.6 152.7, 155.3
30.1, 39.9, 50.7 131.1, 155.0
141.2, 152.8,
86.5
86.4
86.8
62.1 168.9 125.0, 127.8,
129.2
61.6 169.0 114.5, 126.2
155.5, 159.1
61.5 168.8 126.9, 132.4
55.6 164.8, 126.6,
202.0 128.8, 130.3
58.5 168.9 114.2, 127.7
VIIIb 68.7 66.6, 67.8, 68.1,
14.6, 16.0,
124.5, 151.2,
86.9
68.4
42.0, 55.4, 57.5 156.2, 160.9
contain a singlet of methyl, two doublets of methylene,
and expected numbers of ferrocenyl and aryl proton
signals.
IIc, and IId with acetoacetic ester, starting com-
pounds IIa, IIb, and IId were isolated and charac-
terized by H NMR spectra (Table 1).
1
After short refluxing ( 5 min) of pyrazolines IIa,
Note that the reaction of ferrocenyl-4,5-dihydro-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 12 2004

1834
KLIMOVA et al.
Table 3. Yields, melting points, and elemental analyses of compounds IIa, IIc, IId, Va Vc, VIa VId, VIIa VIIc, and
VIIIa VIIId
Found, %
Calculated, %
Comp.
no.
Yield,
%
mp,
C
Formula
C
H
Fe
N
C
H
Fe
N
IIa
IIc
IId
Va
Vb
Vc
VIa
VIb
VIc
VId
VIe
VIIa
VIIb
VIIc
VIIIa
VIIIb
VIIIc
VIIId
59
61
57
68
70
71
69
72
77
71
76
62
71
74
63
67
68
59
113 114
134 135
164 165
183 184
172 173
211 213
173 174
164 165
192 194
232 233
313 314
174 175
168 169
195 197
187 188
206 208
202 203
224 226
69.23
55.64
63.19
69.75
67.69
58.83
70.11
67.74
58.44
64.53
66.51
68.02
66.27
57.48
66.49
66.26
55.89
62.27
5.41
4.28
4.92
6.11
5.74
4.92
5.69
6.16
4.63
5.61
5.52
6.01
6.05
4.67
5.51
5.83
4.38
4.84
16.86
13.81
25.67
13.67
12.91
11.18
13.42
12.48
11.24
21.67
13.58
12.42
11.68
10.90
13.64
11.69
11.47
21.28
8.25 C19H18FeN2
69.11
55.78
63.05
69.91
67.88
58.68
69.91
67.88
58.68
64.65
66.68
67.88
66.11
5.50
4.19
5.06
5.87
5.92
4.72
5.87
5.92
4.72
5.42
5.35
5.92
5.98
4.83
5.98
5.06
4.29
5.02
16.91 8.48
13.65 6.85
25.50 6.39
13.55 6.79
12.63 6.33
11.37 5.70
13.55 6.79
12.63 6.33
11.37 5.70
21.47 5.38
13.49 6.76
12.63 6.33
11.82 5.93
10.72 5.37
11.82 5.93
21.55 5.40
11.33 5.67
21.40 5.36
6.77 C19H17BrFeN2
6.57 C23H22Fe2N2
6.67 C24H24FeN2O
6.21 C25H26FeN2O2
5.83 C24H23BrFeN2O
6.97 C24H24FeN2O
6.47 C25H26FeN2O2
5.54 C24H23BrFeN2O
5.49 C28H28Fe2N2O
6.53 C23H22FeN2O2
6.21 C25H26FeN2O2
5.72 C26H28FeN2O3
5.46 C25H25BrFeN2O2 57.61
6.67 C23H22FeN2O2
5.69 C26H28FeN2O3
5.80 C23H21BrFeN2O2 56.01
5.42 C27H26Fe2N2O2 62.10
66.11
64.90
pyrazoles with -dicarbonyl compounds proceeds
stereoselectively. In all the cases, enaminocarbonyl
derivatives Va Vc, VIa Vd, VIIa Vc, and VIIIb
were obtained as a single, probably E, geometric
isomer [10].
(E)-1-[2-(4-oxopent-2-en-1-yl)]-4,5-dihydropy-
razoles Va Vc and VIa VId. A mixture of 3.3 mmol
of dihydropyrazole Ia Ic, IIa IId and 5 ml of acetyl-
acetone was refluxed for 5 min. After cooling, the
reaction mixture was diluted with 50 ml of ether.
Crystals formed and were filtered off, washed with
ether, and dried in air. Purification was carried out by
column chromatography.
EXPERIMENTAL
1
The H and 13C NMR spectra were measured on a
Reaction of ferrocenyl-4,5-dihydropyrazoles
Ia Ic and IIa IId with acetoacetic ester was carried
out in a similar way. Reaction products were preci-
pitated with ether and crystallized from benzene to
obtain (E)-1-[2-(ethoxycarbonyl)-1-methylvinyl]-4,5-
dihydropyrazoles VIIa VIIc and VIIIb and starting
pyrazoles IIa, IIc, and IId (Tables 1 3).
Varian Unity-Inova spectrometer (300 and 75 MHz,
respectively) for CDCl3 solutions against internal
1
TMS. The H and 13C NMR spectral data are listed
in Tables 1 and 2. Column chromatography was
carried out on Al2O3 (Brockmann activity grade III),
eluent hexane ether (2:1 v/v). The yields and ele-
mental analyses of the obtained compounds are listed
in Table 3.
Synthesis of acetoacetic pyrazolides VIIIa, VIIIc,
and VIIId. A mixture of 3.3 mmol of dihydropyra-
zole IIa, IIc, or IId and 5 ml of acetoacetic ether was
refluxed for 30 min. Excess acetoacetic ester was
removed by steam distillation, and the residue was
subjected to column chromatography.
Reagents purchased from Aldrich were used: ferro-
cenecarbaldehyde, 99%; 4-methoxybenzaldehyde,
98%; acetylferrocene, 95%; 4-bromobenzaldehyde,
99%; 4-methoxyacetophenone, 99%; 4-bromoaceto-
phenone, 98%; benzaldehyde, 99%; and acetophenone,
99%.
ACKNOWLEDGMENTS
, -Unsaturated ketones IIIa IIIc and IVa IVd
were prepared from acetylferrocene and corresponding
carbaldehydes or ferrocenecarbaldehyde, and cor-
responding ketones in aqueous alcoholic alkali [5].
The work was financially supported by DRAPA
UNAM (grant no. IN207102). The authors express
their gratitude to O.S.Y. Munos for measuring the
NMR spectra.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 12 2004

REACTION OF MONOCYCLIC FERROCENYL-4,5-DIHYDROPYRAZOLES
1835
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