Synthesis of ferrocenyl pyrazoles by the reaction of (2-formyl-1-chlorovinyl)ferrocene with hydrazines

Article abstract of DOI:10.1016/j.jorganchem.2007.07.029

Synthesis of ferrocenyl-substituted pyrazoles via the reaction between (2-formyl-1-chlorovinyl)ferrocene and hydrazine derivatives is described. Depending upon the substitution pattern of hydrazine, the reaction affords 1-alkyl/aryl-5-ferrocenylpyrazoles and/or 1-alkyl/aryl-3-ferrocenylpyrazoles. The reaction appears to be general for a variety of hydrazine derivatives.

Full text of DOI:10.1016/j.jorganchem.2007.07.029

Journal of Organometallic Chemistry 692 (2007) 5026–5032
www.elsevier.com/locate/jorganchem
Synthesis of ferrocenyl pyrazoles by the reaction
of (2-formyl-1-chlorovinyl)ferrocene with hydrazines
*
Metin Zora , Meral Go¨rmen
Department of Chemistry, Faculty of Arts and Sciences, Middle East Technical University, 06531 Ankara, Turkey
Received 23 June 2007; accepted 21 July 2007
Available online 27 July 2007
Abstract
Synthesis of ferrocenyl-substituted pyrazoles via the reaction between (2-formyl-1-chlorovinyl)ferrocene and hydrazine derivatives is
described. Depending upon the substitution pattern of hydrazine, the reaction affords 1-alkyl/aryl-5-ferrocenylpyrazoles and/or 1-alkyl/
aryl-3-ferrocenylpyrazoles. The reaction appears to be general for a variety of hydrazine derivatives.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Ferrocene; Ferrocenyl; Pyrazole; Hydrazine; Hydrazinium salt; Hydrazide; Propenal; Density functional theory; B3LYP
1. Introduction
Although pyrazoles are among the most thoroughly stud-
ied compounds [7], we were surprised that there has been
very limited study of the ferrocenyl-substituted pyrazoles
[8]. In this regard, as shown by Terent’ev and co-workers
[9], the reaction between (2-formyl-1-chlorovinyl)ferrocene
(1) and hydrazines (2) represents a rapid entry into ferroce-
nyl pyrazoles (3) (Scheme 1), but this reaction was not
studied in much detail and the low yields of ferrocenyl pyr-
azoles 3 were obtained. As part of a program to synthesize
new ferrocenyl-substituted heterocyclic compounds as
potential pharmaceuticals, we have reinvestigated this reac-
tion and improved the yields [10]. We herein report the
results of this study.
Pyrazoles have occupied a unique position in the design
and synthesis of novel biologically active agents that exert
remarkable anticancer activities [1]. In fact, pyrazoles have
been studied for over a century as an important class of
heterocyclic compounds and still continue to attract con-
siderable attention due to the broad range of biological
activities they possess, including analgesic, antimicrobial,
antiviral, anti-inflammatory, hypoglycemix, anti-hyperten-
sive and antitumor properties [1,2]. Recent studies have
shown that the integration of a ferrocenyl group into such
structures may enhance their biological activities or gener-
ate new medicinal properties [3,4]. Due to its unique
structure, different membrane-permeation properties and
anomalous metabolism, ferrocene is often incorporated
into a compound in order to obtain unexpected or
enhanced biological activities [3,4]. Thus, in recent years,
considerable effort has been devoted to the synthesis of
new ferrocene derivatives since the properly functionalized
derivatives could be potential antitumor substances [5,6].
2. Results and discussion
2.1. Synthesis of starting materials
(2-Formyl-1-chlorovinyl)ferrocene (3-chloro-3-ferroce-
nylpropenal) (1) was synthesized from acetylferrocene
according to the well-known literature procedure [11], in
which treatment of acetylferrocene with phosphorous oxy-
chloride in DMF led to formation of (2-formyl-1-chlorovi-
nyl)ferrocene (1). Acetylferrocene is readily available in
large quantities from ferrocene according to a standard
*
Corresponding author. Tel.: +90 312 2103213; fax: +90 312 2103200.
E-mail address: zora@metu.edu.tr (M. Zora).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.07.029

M. Zora, M. Go¨rmen / Journal of Organometallic Chemistry 692 (2007) 5026–5032
5027
Cl
C
bons in 1,3-isomer, i.e. jDd(C5–C3)1,5-isomerj < jDd(C3–
C5)1,3-isomerj.
CH-CHO
N
R-NH-NH2 (2, R = H, Ph)
N
R
The reaction between ferrocenylpropenal 1 and hydra-
zine dihydrochloride (2A) led to formation of a pyrazole
derivative, which was tentatively assigned as 5-ferro-
cenylpyrazole (3A) (entry A). It should be noted that owing
to annular tautomerism, pyrazoles can exist in two tauto-
meric forms such as 3A and 4A. In fact, proton transfer
in pyrazoles is a formally 1,5-hydrogen shift and the barri-
ers for such processes in both solution and solid state are in
the range of 10–14 kcal/mol [14]. As anticipated, tautomers
3A and 4A can be in equilibrium or interconvert in part.
Unfortunately, we were unsuccessful to obtain a well-
resolved 13C NMR spectrum from this compound at
25 ꢁC and even ꢀ15 ꢁC to identify the corresponding tauto-
mer(s). In fact, pyrazole 3A is a known compound [9], but
there is a lack of specific spectroscopic data (such as 13C
NMR data) in the literature to differentiate it from its tau-
tomer 4A. Our efforts to spectroscopically distinguish
between pyrazoles 3A and 4A are going on.
Fe
Fe
CH3CH2OH, 25 ºC, 2 h
1
3A R = H (18%)
3B R = Ph (21%)
Scheme 1.
protocol [12]. Hydrazine derivatives 2 used in this study
were all commercially available.
2.2. Synthesis of ferrocenyl pyrazoles 3 and 4
The reaction was initially examined under a variety of
conditions, and the best results were obtained as follows:
3-chloro-3-ferrocenylpropenal (1) was first reacted with
the excess amounts (3 equivalents) of hydrazine derivative
(2) at 25 ꢁC in dioxane under argon for 2.5 h. The resulting
mixture was then refluxed at 100 ꢁC for 6 h, and the prod-
ucts were isolated by flash chromatography. The results are
summarized in Table 1. If available, hydrazinium salts,
instead of hydrazines, were used in these reactions since
they gave relatively higher yields of pyrazoles.
As can be seen from Table 1, 1-alkyl/aryl-5-ferro-
cenylpyrazoles (3) and/or 1-alkyl/aryl-3-ferrocenylpyraz-
oles (4) were resulted from these reactions, which are
commonly called 1,5- and 1,3-isomers, respectively. It
should be noted that 1,5- and 1,3-isomers of pyrazoles
can be differentiated on the basis of their 13C NMR spec-
tra, as concluded from the spectral data of similar pyrazole
derivatives [13]. In general, C5 peak in 1,5-isomer is rela-
tively upfield and appears around 140 ppm while corre-
sponding C3 peak in 1,3-isomer is relatively downfield
and resonates around 150 ppm (see Table 1 for atom num-
bering). Moreover, in 1,5-isomer, the absolute value of
chemical shift difference between C5 and C3 carbons is
mostly smaller than that between respective C3 and C5 car-
We also calculated the relative energies of pyrazoles 3A
and 4A at the density functional theory (DFT) level
(B3LYP/6-31G*) [15,16] by using the GAUSSIAN-98 program
package [17], and found that 4A is more stable than 3A by
0.3 kcal/mol. Note that, in gas phase (DFT calculations),
4A is the more stable while, in solution and solid state, it
might correspond to a metastable structure, which requires
further study. As shown by Elguero and co-workers [13d],
pyrazoles can exist in different tautomeric forms depending
upon their physical phase or state. For instance, in gas
phase and solution, 3-phenylpyrazole is more stable than
its tautomer, 5-phenylpyrazole. However, in solid state,
crystals of 3-phenylpyrazole evolved to be 5-phenylpyraz-
ole [13d].
The reaction of ferrocenylpropenal 1 with phenylhydr-
azine dihydrochloride (2B) afforded 5-ferrocenyl-1-phen-
ylpyrazole (3B) along with a very small amount of
3-ferrocenyl-1-phenylpyrazole (4B) (entry B). Interestingly,
the reaction between ferrocenylpropenal 1 and (2-hydroxy-
ethyl)hydrazinium dichloride (2C) [18] produced 2-(3-ferro-
cenylpyrazol-1-yl)ethanol (4C) as the major product,
accompanied by the very small amount of 2-(5-ferro-
cenylpyrazol-1-yl)ethanol (3C) (entry C). On the other
hand, the reaction of ferrocenylpropenal 1 with ben-
zylhydrazine dihydrochloride (2D) led to a single pyrazole
derivative, 1-benzyl-5-ferrocenylpyrazole (3D) (entry D). It
should be noted that tautomeric assignments of pyrazoles
3B–D and 4B–C were based on both chemical shifts and
absolute values of chemical shift differences of correspond-
ing C3 and C5 carbons, as mentioned before. Note that the
structures of ferrocenyl pyrazoles 3B, 3D and 4C were
unambiguously identified by X-ray analysis as well, but
the results of this study will be reported separately as a part
of another study.
Table 1
Reaction of (2-formyl-1-chlorovinyl)ferrocene (1) with hydrazines 2
3
5
N1
Cl
C
1. R-NH-NH2.xHCl (2)
Dioxane, 25 ºC, 2.5 h
CH-CHO
1
N
N
R
5
3
N
Fe
Fe
Fe
+
R
2. Dioxane, 100 ºC, 6 h
3 (1,5-isomer)
4 (1,3-isomer)
1
Entrya
R
x
Products (isolated yield, %)
A
B
C
D
E
F
G
a
H
Ph
2
1
3A (51)
3B (67) + 4B (4)
3C (3) + 4C (34)
3D (55)
3E (47)
3F (60)
CH2-CH2-OH
CH2-Ph
p-C6H4-CO2H
o-C5H4N
2
2
1
0
0
CO-p-C6H4-OH
4G (43) + 3A (50)
The reaction of ferrocenylpropenal 1 with 4-hydrazino-
benzoic acid (2E) yielded 4-(5-ferrocenylpyrazol-1-yl)ben-
zoic acid (3E) (entry E). Similarly, the reaction between
Entry letters define R group for compounds 2, 3 and 4, and x for
compound 2.

5028
M. Zora, M. Go¨rmen / Journal of Organometallic Chemistry 692 (2007) 5026–5032
ferrocenylpropenal 1 and 2-pyridiniohydrazinium dichlo-
ride (2F) [19] led to 2-(5-ferrocenylpyrazol-1-yl)pyridine
(3F) (entry F). On the other hand, the reaction of ferroce-
nylpropenal 1 with 4-hydroxybenzhydrazide (2G) afforded
two products, namely (3-ferrocenylpyrazol-1-yl)(4-hydroxy-
phenyl)methanone (4G) and 5-ferrocenylpyrazole (3A)
(entry G).
For the formation of pyrazoles 3 (1,5-isomer) and 4
(1,3-isomer), three mechanistic pathways are available
as depicted in Scheme 2. The reaction proceeds via tan-
dem conjugate addition–elimination of hydrazine 2 with
ferrocenylpropenal 1 followed by cyclization and/or con-
densation of the resulting b-hydrazinoenones 5 and 6
(pathways A and B), or via condensation of hydrazine
2 with ferrocenylpropenal 1 followed by cyclization
through tandem conjugate addition–elimination of the
resulting a,b-unsaturated hydrazone 7 (pathway C). It
should be noted that pathway A leads to 1,3-pyrazole
isomer 4 while pathways B and C go to 1,5-pyrazole iso-
mer 3. Apparently, depending upon the substitution pat-
tern of hydrazine derivative 2, one pathway or more
than one pathway can be operative during the course
of the reaction.
Interestingly, the reaction of ferrocenylpropenal 1 with
4-hydroxybenzhydrazide (2G) produced 5-ferrocenylpy-
razole (3A) in addition to pyrazole 4G (entry G). For
the formation of pyrazole 3A, we have proposed two
mechanistic pathways as illustrated in Scheme 3. Accord-
ing to pathway A, formation of pyrazole 3A may not
actually represent a different reactivity pattern since it is
a secondary product of the reaction and results from
the initially formed pyrazole 4G by hydrolysis. Nucleo-
philic addition of benzhydrazide 2G to carbonyl function
of pyrazole 4G provides a hydrazide derivative, 8, which
is not normally stable and eliminates benzoic acid hydra-
zide 9 to give pyrazole 4A. As mentioned before, pyrazole
4A can be in equilibrium with and/or interconvert to its
tautomer 3A. Alternatively, as outlined in pathway B,
benzhydrazide 2G may react with itself via nucleophilic
addition, yielding hydrazide derivative 10. Elimination
of benzoic acid hydrazide 9 from 10 then affords in situ
hydrazine, the reaction of which with ferrocenylpropenal
1 yields pyrazole 3A as well (Scheme 3). At present, it is
not clear which mechanism is operating but there are prece-
dents for both pathways [20,21].
3. Conclusion
In summary, we have reinvestigated in detail the reac-
tion between (2-formyl-1-chlorovinyl)ferrocene (1) and
hydrazines 2 and improved the yields of pyrazoles 3 and/
or 4. In most cases, 1,5-pyrazole isomers 3 has resulted
from these reactions as the single or the major products.
The regioselectivity of the reactions is mainly governed
by the nature of the substituents in hydrazines 2. Due to
the ready availability of ferrocenylpropenal 1 and hydra-
zines 2, this method represents a versatile synthesis of ferr-
ocenyl-substituted pyrazoles 3 and/or 4.
4. Experimental
4.1. General consideration
Nuclear magnetic resonance (1H and 13C) spectra were
recorded on a Bruker Spectrospin Avance DPX400 Ultra-
PATHWAY A
O
R-NH-NH (2)
2
H
NH
N R
-H O
-HCl
2
N
Fc
Fc
N
H
Fc
Fc
R
5
4
O
PATHWAY B
O
H
NH
R-NH-NH (2)
2
N
H
N
2
N
R
6
-H O
2
-HCl
R
Fc
Cl
1
3
PATHWAY C
N
NH
R-NH-NH (2)
2
N
N
Fc
Fc
Cl
-H O
2
-HCl
R
R
7
3
Scheme 2.

M. Zora, M. Go¨rmen / Journal of Organometallic Chemistry 692 (2007) 5026–5032
5029
O
PATHWAY A
HO
C NH NH
2
OH
O
C
N C NH NH
OH
O
2G
N
Fc
N C
OH
N
Fc
8
4G
OH
O
O
−
HO
C NH NH C
OH
9
N
N H
N
Fc
N
Fc
H
4A
3A
Fc C CH-CHO
Cl
PATHWAY B
1
O
OH
O
H N NH
HO
C NH NH
HO
C NH NH
NH
C
OH
2
2
2
2
− 9
NH
2G
10
2
Scheme 3.
shield (400 MHz) spectrometer. Chemical shifts are
reported in parts per million (d) downfield from an inter-
nal tetramethylsilane reference. Coupling constants (J val-
ues) are reported in hertz (Hz), and spin multiplicities are
indicated by the following symbols: s (singlet), d (dou-
blet), t (triplet), q (quartet), m (multiplet). DEPT 13C
NMR information is given in parenthesis as C, CH,
CH2 and CH3. Infrared spectra were recorded on a Per-
kin–Elmer 1600 Series FT-IR spectrometer or on a Bru-
ker Vertex 70 Spectrometer using attenuated total
reflection (ATR). Band positions are reported in recipro-
cal centimeters (cmꢀ1). Mass spectra (MS) were obtained
on a Finnigan MAT 95 spectrometer, using electron
impact (EI) at 70 eV; m/z values are reported. High reso-
lution mass spectra (HRMS) were obtained on a Finnigan
MAT 95 spectrometer by preselected-ion peak matching
at R ꢁ 10,000 to be within 3 ppm of the exact masses.
Flash chromatography was performed using thick-walled
glass columns and ‘flash grade’ silica (Merck 230–400
mesh). Routine thin layer chromatography (TLC) was
effected by using precoated 0.25 mm silica gel plates pur-
chased from Merck. The relative proportion of solvents in
mixed chromatography solvents refers to the volume:vol-
ume ratio. (2-Formyl-1-chlorovinyl)ferrocene (1) [14] and
acetylferrocene [15] were synthesized according to the
well-known literature procedures. All other commercially
available reagents and reactants were obtained in reagent
grade and used without purification. All reaction solvents
were distilled for purity. Diethyl ether, THF and dioxane
were distilled from sodium/benzophenone ketyl. The inert
atmosphere was created by slight positive pressure (ca.
0.1 psi) of argon.
4.2. General procedure for the synthesis of ferrocenyl
pyrazoles 3 and 4 (Table 1)
To the solution of (2-formyl-1-chlorovinyl)ferrocene (1)
(100 mg, 0.364 mmol) in dioxane (25 mL) under argon
was added hydrazine derivative or salt (2) (1.092 mmol).
The resulting mixture was stirred for 2.5 h at room tem-
perature and then heated at reflux for 6 h. After the reac-
tion was complete, the mixture was cooled to 25 ꢁC, and
the solvent was removed on a rotary evaporator. The res-
idue was dissolved in water (20 mL) and extracted with
chloroform (3 · 30 mL). The combined chloroform layers
were dried over magnesium sulfate and removed in a
rotary evaporator. Final purification was achieved
through flash chromatography on silica gel (eluent: hex-
ane/EtOAc from 19:1 to 1:1). The products given in Table
1 were isolated with the indicated yields.

5030
M. Zora, M. Go¨rmen / Journal of Organometallic Chemistry 692 (2007) 5026–5032
4.3. Spectral data for products
4.3.6. 1-Benzyl-5-ferrocenyl-1H-pyrazole (3D)
1H NMR (CDCl3): d 7.44 (s, 1H), 7.23 (t, 2H,
J = 7.28 Hz), 7.15 (t, 1H, J = 7.28 Hz), 6.96 (d, 2H,
J = 7.28 Hz), 6.35 (s, 1H), 5.42 (s, 2H), 4.29 (s, 2H), 4.17
(s, 2H), 4.00 (s, 5H); 13C NMR (CDCl3): d 141.7 (C),
139.1 (C), 137.7 (CH), 128.6 (CH), 127.3 (CH), 126.2
(CH), 106.0 (CH), 74.9 (C), 70.5 (CH), 68.8 (CH), 68.4
(CH), 53.3 (CH2); IR (neat): 3142, 3109, 2950, 2896, 1556,
1502, 1409, 1321, 1231, 1071, 873, 825, 765 cmꢀ1; MS (EI):
342 (M+), 277, 252, 223, 185, 157, 121, 91, 65, 56; HRMS
(EI): calcd. for C20H18FeN2: 342.0819. Found: 342.0817.
4.3.1. 5-Ferrocenyl-1H-pyrazole (3A)
1H NMR (CDCl3): d 7.52 (s, 1H), 6.33 (s, 1H), 4.58 (s,
2H), 4.28 (s, 2H), 4.04 (s, 5H), NH peak was not observed
due to H/D exchange and/or tautomerism; IR (neat): 3115,
3026, 2875, 2840, 2816, 1598, 1565, 1463, 1415, 1289, 1102,
1053, 999, 937, 810, 764 cmꢀ1; MS (EI): 252 (M+), 250,
224, 187, 166, 158, 133, 121, 103, 77; HRMS (EI): calcd.
for C13H12FeN2: 252.0350. Found: 252.0352.
4.3.2. 5-Ferrocenyl-1-phenyl-1H-pyrazole (3B)
1H NMR (CDCl3): d 7.62 (s, 1H), 7.40 (m, 5H), 6.50 (s,
1H), 4.17 (s, 2H), 4.14 (s, 2H), 4.05 (s, 5H); 13C NMR
(CDCl3): d 141.5 (C), 140.4 (C), 140.0 (CH), 128.8 (CH),
128.0 (CH), 126.1 (CH), 106.8 (CH), 75.1 (C), 69.9 (CH),
68.8 (CH), 68.6 (CH); IR (CH2Cl2): 3089, 3036, 1665,
4.3.7. 4-(5-Ferrocenylpyrazol-1-yl)benzoic acid (3E)
1H NMR (CDCl3): d 8.00 (d, 2H, J = 7.5 Hz), 7.86 (d,
1H, J = 8.5 Hz), 7.05 (d, 2H, J = 7.5 Hz), 6.68 (d, 1H,
J = 8.5 Hz), 4.63 (t, 2H, J = 1.7 Hz), 4.37 (t, 2H,
J = 1.7 Hz), 4.19 (s, 5H), carboxylic acid peak was not
observed due to H/D exchange; 13C NMR (CDCl3): d
170.5 (C), 139.1 (CH), 137.8 (C), 137.0 (C), 132.3 (CH),
120.3 (C), 117.8 (CH), 111.9 (CH), 83.0 (C), 70.2 (CH),
70.1 (CH), 67.4 (CH); IR (CH2Cl2): 3057, 2928, 2851,
2671, 2542, 1727, 1694, 1603, 1451, 1417, 1316, 1286, 1262,
1171, 1127, 1070, 746, 733, 719 cmꢀ1; MS (EI): 372 (M+),
370, 329, 307, 251, 234, 205, 178, 137, 120, 65, 56; HRMS
(EI): calcd. for C20H16FeN2O2: 372.0561. Found: 372.0559.
1597, 1557, 1498, 1402, 1259, 1145, 971, 923, 870 cmꢀ1
;
MS (EI): 328 (M+), 326, 263, 235, 207, 170, 153, 121, 77,
56; HRMS (EI): calcd. for C19H16FeN2: 328.0663. Found:
328.0661.
4.3.3. 3-Ferrocenyl-1-phenyl-1H-pyrazole (4B)
1H NMR (CDCl3): d 7.84 (d, 1H, J = 2.4 Hz), 7.71 (d,
2H, J = 7.8 Hz), 7.44 (t, 2H, J = 7.8 Hz), 7.25 (t, 1H,
J = 7.8 Hz), 6.48 (d, 1H, J = 2.4 Hz), 4.76 (s, 2H), 4.29
(s, 2H), 4.07 (s, 5H); 13C NMR (CDCl3): d 152.5 (C),
140.3 (C), 129.4 (CH), 127.4 (CH), 126.0 (CH), 119.0
(CH), 105.6 (CH), 78.4 (C), 69.6 (CH), 68.7 (CH), 66.9
(CH); IR (CH2Cl2): 3090, 3030, 2959, 2865, 1681, 1649,
4.3.8. 2-(5-Ferrocenylpyrazol-1-yl)pyridine (3F)
1H NMR (CDCl3): d 8.11 (ddd, 1H, J = 8.6, 7.5,
1.8 Hz), 7.87 (d, 1H, J = 9.0 Hz), 7.58 (ddd, 1H, J = 8.6,
7.5, 1.8 Hz), 7.22 (d, 1H, J = 8.5 Hz), 6.77 (ddd, 1H,
J = 8.6, 7.5, 1.8 Hz), 6.65 (d, 1H, J = 9.0 Hz), 4.58
(t, 2H, J = 1.9 Hz), 4.35 (t, 2H, J = 1.9 Hz), 4.18 (s, 5H);
13C NMR (CDCl3): d 155.9 (C), 146.9 (CH), 139.1 (CH),
138.5 (CH), 136.7 (C), 118.1 (CH), 115.8 (CH), 107.6
(CH), 83.4 (C), 70.1 (CH), 70.0 (CH), 67.3 (CH); IR (neat):
3178, 3142, 3048, 2951, 1561, 1535, 1435, 1301, 1141, 1088,
867, 805, 769 cmꢀ1; MS (EI): 329 (M+), 302, 300, 271, 264,
237, 210, 184, 156, 149, 120, 89, 67; HRMS (EI): calcd. for
C18H15FeN3: 329.0615. Found: 329.0613.
1598, 1557, 1506, 1458, 1257, 1129, 1043, 868, 820 cmꢀ1
;
MS (EI): 328 (M+), 326, 263, 246, 206, 178, 149, 121, 91,
77, 56; HRMS (EI): calcd. for C19H16FeN2: 328.0663.
Found: 328.0665.
4.3.4. 2-(5-Ferrocenylpyrazol-1-yl)ethanol (3C)
1H NMR (CDCl3): d 7.46 (d, 1H, J = 1.8 Hz), 6.30 (d,
1H, J = 1.8 Hz), 4.49 (s, 2H), 4.36 (s, 2H), 4.33 (t, 2H,
J = 4.5 Hz), 4.18 (s, 5H), 4.02 (t, 2H, J = 4.5 Hz), 3.09
(br s, 1H); 13C NMR (CDCl3): d 141.4 (C), 138.7 (CH),
106.0 (CH), 74.9 (C), 69.6 (CH), 68.9 (CH), 68.8 (CH),
61.8 (CH2), 51.0 (CH2); IR (neat): 3331, 2965, 2937,
1562, 1460, 1331, 1070, 1043, 824, 800 cmꢀ1; MS (EI):
296 (M+), 294, 265, 252, 231, 200, 187, 146, 121, 103;
HRMS (EI): calcd. for C15H16FeN2O: 296.0612. Found:
296.0610.
4.3.9. (3-Ferrocenylpyrazol-1-yl)(4-hydroxyphenyl)-
methanone (4G)
1H NMR (CDCl3): d 8.33 (s, 1H), 8.21 (d, 2H,
J = 7.95 Hz), 6.89 (d, 2H, J = 7.95 Hz), 6.51 (s, 1H), 5.87
(s, OH), 4.81 (s, 2H), 4.40 (s, 2H), 4.14 (s, 5H); 13C
NMR (CDCl3): d 165.1 (C), 160.3 (C), 156.6 (C), 134.5
(CH), 131.5 (CH), 123.6 (C), 115.3 (CH), 107.9 (CH),
78.2 (C), 71.2 (CH), 71.1 (CH), 68.6 (CH); IR (neat):
3353, 3149, 1699, 1606, 1558, 1417, 1384, 1357, 1311,
1271, 1231, 1190, 1057, 895, 821, 756 cmꢀ1; MS (EI): 372
(M+), 370, 307, 252, 224, 187, 158, 141, 121, 93, 84; HRMS
(EI): calcd. for C20H16FeN2O2: 372.0561. Found: 372.0563.
4.3.5. 2-(3-Ferrocenylpyrazol-1-yl)ethanol (4C)
1H NMR (CDCl3): d 7.31 (s, 1H), 6.22 (s, 1H), 4.76 (s,
2H), 4.35 (s, 2H), 4.21 (t, 2H, J = 4.3 Hz), 4.12 (s, 5H),
3.97 (t, 2H, J = 4.3 Hz), 3.52 (br s, 1H); 13C NMR
(CDCl3): d 151.3 (C), 130.8 (CH), 103.0 (CH), 78.3 (C),
69.4 (CH), 68.3 (CH), 66.6 (CH), 62.1 (CH2), 53.5 (CH2);
IR (neat): 3229, 3142, 2950, 2869, 1556, 1502, 1408, 1349,
1230, 1067, 824, 764 cmꢀ1; MS (EI): 296 (M+), 294, 278,
264, 231, 213, 199, 173, 148, 121, 103, 81; HRMS (EI):
calcd. for C15H16FeN2O: 296.0612. Found: 296.0614.
Acknowledgements
The authors thank the Scientific and Technical Research
Council of Turkey (104T202) and the Research Board of

M. Zora, M. Go¨rmen / Journal of Organometallic Chemistry 692 (2007) 5026–5032
5031
(c) M.A. Sierra, M.J. Mancheno, R. Vicente, M. Gomez-Galleo, J.
Org. Chem. 66 (2001) 8920;
Middle East Technical University (BAP-2004-07-02-00-80)
for financial support of this research, and Prof. Ahmet M.
(d) B.F. Bonini, C. Femoni, M. Comes-Franchini, M. Fochi, G.
Mazzanti, A. Ricci, G. Varchi, Synlett (2001) 1092;
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(f) M. Zora, B. Yucel, N.B. Peynircioglu, J. Organomet. Chem. 656
(2002) 11;
¨
Onal (METU) for the use of Bruker Vertex 70 IR Spec-
trometer, and Dr. Holm Frauendorf (University of Go¨ttin-
gen) for obtaining MS and HRMS spectra.
(g) M. Zora, B. Yucel, S. Acikalin, Tetrahedron Lett. 44 (2003) 2237;
(h) M. Zora, M. Kokturk, T. Eralp, Tetrahedron 62 (2006) 10344;
(i) M. Zora, C. Acikgoz, T.A. Tumay, M. Odabasoglu, O. Buyuk-
gungor, Acta Crystallogr., Sect. C 62 (2006) m327;
(j) M. Zora, C. Acikgoz, M. Odabasoglu, O. Buyukgungor, J.
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