N-(ethoxycarbonyl)ferrocenecarboxamide: Synthesis and use as the pronucleophile in the Mitsunobu reaction

Article abstract of DOI:10.1016/j.jorganchem.2011.08.030

The title compound has been synthesized in the reaction of ferrocene with ethoxycarbonyl isocyanate in methanesulfonic acid. It has been found that it undergoes N-alkylation with benzyl alcohols under classical Mitsunobu conditions (PPh₃/DEAD). However, in the reaction with cholesterol and stigmasterol O-alkylation with inversion of configuration occurred (confirmed by hydrolysis of the product obtained from cholesterol to epicholesterol). The structure of the product obtained from p-nitrobenzyl alcohol was determined by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2011.08.030

Journal of Organometallic Chemistry 696 (2011) 3826e3830
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Note
N-(ethoxycarbonyl)ferrocenecarboxamide: Synthesis and use as the
pronucleophile in the Mitsunobu reaction
,
b
Anna Wrona-Piotrowicza, Janusz Zakrzewskia , Lucjan Jerzykiewicz
*
a
ꢀ
ꢀ
Department of Organic Chemistry, University of Łódz, 91-403 Łódz, Tamka 12, Poland
b Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
The title compound has been synthesized in the reaction of ferrocene with ethoxycarbonyl isocyanate in
methanesulfonic acid. It has been found that it undergoes N-alkylation with benzyl alcohols under
classical Mitsunobu conditions (PPh3/DEAD). However, in the reaction with cholesterol and stigmasterol
O-alkylation with inversion of configuration occurred (confirmed by hydrolysis of the product obtained
from cholesterol to epicholesterol). The structure of the product obtained from p-nitrobenzyl alcohol was
determined by X-ray diffraction.
Received 22 July 2011
Received in revised form
19 August 2011
Accepted 23 August 2011
Keywords:
Ferrocene
Ó 2011 Elsevier B.V. All rights reserved.
Ethoxycarbonyl isocyanate
Mitsunobu reaction
Cholesterol
Epicholesterol
Stigmasterol
1. Introduction
ferrocenecarboxamide 2, which reacts with alcohols and the DEAD/
PPh3 system to afford products of the N- or O- alkylation,
The Mitsunobu reaction is a versatile method for dehydrogen-
ative coupling of an alcohol with an acid (pronucleophile) by using
a combination of an oxidizing azo reagent (usually diethyl azodi-
carboxylate (DEAD)) and reducing phosphine reagent (usually
PPh3) [1e4]. It found a number of applications in the ferrocene
chemistry for transformation of ferrocenyl alcohols into other
derivatives [5e10]. In contrast, to our knowledge there is only one
report on the Mitsunobu reaction with a ferrocenyl pronucleophile
[11]. We found that N-(ethoxycarbonyl)ferrocenecarbothioamide 1
is sufficiently acidic to form under the Mitsunobu conditions the
conjugated anion, which undergoes S-alkylation with alcohols
(Scheme 1). The reaction has been applied to synthesis of ferrocenyl
conjugates of some biomolecules (cholesterol, stigmasterol,
adenosine).
Taking into account a continuously increasing interest in
synthesis of functionalized ferrocenes, stimulated by their appli-
cations in many branches of science [12] we became interested in
a search of other ferrocenyl pronucleophiles capable of reacting
with alcohols in the Mitsunobu reaction. Herein we report
synthesis of the oxygen analog of 1, N-(ethoxycarbonyl)
depending on the structure of the alcohol.
2. Results and discussion
Compound 2 was synthesized similarly as 1 in the reaction of
ferrocene with ethoxycarbonyl isothiocyanate in methanesulfonic
acid (Scheme 2). The isolated yield of 2 was 68%.
We have found that 2 reacts in THF at room temperature with
benzyl alcohols under classical Mitsunobu conditions (PPh3/DEAD)
to afford the corresponding N-alkylated products 3aec in 42e72%
isolated yields (Scheme 3).
Compounds 3aec were isolated from the reaction mixtures by
silica gel column chromatography and their structure was
confirmed by spectroscopic and elemental analyses data. The IR
spectra of these compounds displayed two strong absorption
bands: first at 1720e1727 cmꢀ1 and the second at 1667e1668 cmꢀ1
.
These bands can be assigned to the stretching vibrations of the
“ carbamate” and “amide” carbonyl groups, respectively. The spectra
did not displayed N-H stretching vibrations bands. In the 13C NMR
spectra of 3aec signals of carbonyl carbons were observed at
171e175 ppm and 155e156 ppm.
The structure of 3b was also confirmed by X-ray diffraction
analysis (vide infra).
* Corresponding author. Tel.: þ48 42 678 4731; fax: þ48 42 678 6583.
E-mail address: janzak@uni.lodz.pl (J. Zakrzewski).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.08.030

A. Wrona-Piotrowicz et al. / Journal of Organometallic Chemistry 696 (2011) 3826e3830
3827
H
N
X
OEt
N
OEt
PPh3, DEAD
THF, rt.
+
R-OH
Fe
Fe
X
S
O
S
O
H
N
N
OEt
OEt
PPh , DEAD
3
R
+
Fe
Fe
O
O
O
O
THF, rt.
1
OH
3a X = H
Scheme 1. Mitsunobu S-alkylation of 1 with alcohols.
2
3b
X = NO2
3c X = CN
Having determined the structures and spectroscopic features of
3aec, we carried out the Mitsunobu reaction of 2 with steroid
alcohols, cholesterol and stigmasterol. We found that similarly as
the analogous reaction with 110 this reaction is relatively sluggish,
but after 3 days at room temperarure we isolated ferrocenyl
substituted steroids 4a,b in 48e56% yield. However, the spectro-
scopic data of these compounds were distinctly different from
those of 3aec. Their IR spectra showed strong absorption bands at
1699 and 1651 cmꢀ1, and 13C NMR spectra displayed two low-field
signals at 163.5 and 161.2 ppm. We hypothesized that in this case O-
alkylation took place and the isolated products have structure 4a,b
(Scheme 4).
Scheme 3. The Mitsunobu reaction of 2 with benzyl alcohols.
angles
O1eC6eC1AeC2A,
and
O1eC6eC1AeC5A
equal
ꢁ
to ꢀ21.49(5) and 151. 73(20)ꢁ, respectively). The three bonds to
the N1 atom are coplanar (the sum of the corresponding angles
equal to 358ꢁ). The C21eO21 carbonyl group is practically
perpendicular to the C6eO1 carbonyl (the angle O1eC6eC21eO21
equals to ꢀ78.99(23)ꢁ) Nevertheless, both carbonyl appear to
undergo conjugation with the nitrogen lone pair (the angles
O1eC6eN1eC7 and C7eN1eC21eO21 equal to ꢀ22.60(27)ꢁ
and ꢀ29.72(3)ꢁ, respectively).
The reaction of 2 with cholesterol and stigmasterol proceeded
stereoselectively with inversion of configuration at C-3 as
confirmed by analysis of coupling constants in the 1H NMR spec-
trum of 4a,b. The signals of the H-3 protons in these compounds
appear as quintets at 5.12e5.13 ppm with J w2.5 Hz (Fig. 2). This
means that the coupling constants of these protons with protons at
C-2 and C-4 are approximately equal, which reveals their equatorial
positions (Jea w Jee). Consequently, the organometallic substituent
3. Conclusion
We have synthesized N-(ethoxycarbonyl)ferrocenecarboxamide
2 and demonstrated that this compound reacts under the Mitsu-
nobu conditions with alcohols to afford, depending on the structure
of alcohol, products of Ne or Oealkylation. In our opinion this may
open a synthetic route to a variety of novel ferrocenyl compounds.
As shown by reaction of 2 with cholesterol and stigmasterol, this
reaction can be used for introduction of ferrocenyl groups into
steroid alcohols.
must occupy an axial (a) position (Fig. 1).
To confirm the O-alkylated structure of 4a we carried out its
hydrolysis in a MeOH-H2O solution containing HCl (Scheme 5). We
isolated epicholesterol 5 in 89% yield along with 2 (83%). The
outcome of this reaction strongly supports the structure and
stereochemistry of 4a.
4. Experimental
The results obtained in this study reveal different reactivity of
compounds 1 and 2 in the Mitsunobu reaction. Whereas compound
1 invariably undergoes S-alkylation, the regiochemistry of alkyl-
ation of 2 depends on the structure of the alcohol. Such a behavior
can be tentatively explained assuming that in the conjugated anion
of 1 (Fig. 2) sulfur is significantly more nucleophilic than nitrogen,
whilst in the anion of 2 nitrogen and oxygen centres have
comparable nucleophilicity. This renders the latter anion sensitive
to the steric factors. P-alkoxyphosphonium salts derived from
unhindered benzyl alcohols formed in the course of the Mitsunobu
reaction alkylate presumably slightly more nucleophilic but steri-
cally more hindered nitrogen, whereas analogous salts derived
from more hindered steroid alcohols prefer the oxygen centre.
All reactions were carried out under argon. All reagents used in
this work are commercially available (Aldrich) and were used
without further purifications. Solvents were dried over appropriate
drying agents and distilled before use. Chromatographic separa-
tions were carried out using Silica gel 60 (Merck, 230e400 mesh
ASTM). The NMR spectra were run on a Varian Gemini 200 BB
(200 MHz for 1H), Bruker Avance (600 MHz for 1H) and Bruker
Avance II(700 MHz for 1H) and IR spectra on an FT-IR Nexus spec-
trometer. Mass spectra and high resolution mass spectrum (HRMS)
were measured on a Finnigan MAT 95 spectrometer. Elemental
analyses were performed by Analytical Services of the Center of
Molecular and Macromolecular Studies of the Polish Academy of
ꢀ
the Sciences (qódz).
2.1. X-ray diffraction study of 3b
The crystal of 3b suitable for X-ray diffraction study was grown
from layered dichloromethane-hexane. The molecular structure of
this compound is displayed in Fig. 3, whereas Table 1 contains
essential structural parameters. The structure confirms the N-
benzylation of 2. The ferrocenyl moiety in 3b adopts an eclipsed
conformation. The C6eO1 carbonyl group is not coplanar with the
adjacent C5H4 ring but twisted towards the iron atom (the dihedral
4.1. Synthesis of 2
To ferrocene (186 mg, 1 mmol) dissolved in chloroform (1 ml),
was added methanesulfonic acid (30 ml) followed by ethox-
ycarbonyl isocyanate (230 mg, 2 mmol). The resulting solution was
stirred at room temperature 2 h, poured into water (200 ml) and
extracted several times with CH2Cl2. The combined extracts were
dried (MgSO4) and concentrated. Column chromatography (eluent:
CH2Cl2-ethyl acetate 5:1) afforded 2 as orange crystals. Yield
H
205 mg (68%). 1H NMR (200 MHz, CDCl3,
d): 7.73 (bs,1H, NH), 4.74 (t,
N
OEt
O=C=N-COOEt
MeSO3H
Fe
Fe
J ¼ 1.9 Hz, C5H4), 4.42 (t, J ¼ 1.9 Hz, C5H4), 4.26 (q, J ¼ 7.2 Hz,
CH2CH3), 4.22 (s, 5H, Cp) 1.30 (t, J ¼ 7.2 Hz, CH2CH3). IR (KBr, cmꢀ1):
3254 (NH), 1759, 1740 (CO). Anal. Calc. for C14H15FeNO3: C, 55.84; H,
5.02; N, 4.65. Found: C, 55.89; H, 4.99; N, 4.71.
O
O
2
Scheme 2. Synthesis of 2.

3828
A. Wrona-Piotrowicz et al. / Journal of Organometallic Chemistry 696 (2011) 3826e3830
R
R
H
PPh3, DEAD
O
N
N
OEt
Fe
+
Fe
THF, rt. 3 days
O
O
O
HO
4a,b
OEt
2
(a): R =
(b): R =
Scheme 4. The Mitsunobu reaction of 2 with cholesterol and stigmasterol.
4.2. The Mitsunobu reaction of 2
IR (CHCl3. cmꢀ1): 2231 (C^N), 1722 (CO), 1668 (C]O). Anal. Calcd
for C22H20FeN2O3 C, 63.48; H, 4.84; N, 6.73.Found: C. 63.50. H. 4.79.
N. 6.69. 3c: Orange powder. Yield 72%. 1H NMR (200 MHz, CDCl3):
Compound 2 (75 mg, 0.25 mmol), the appropriate alcohol
(0.25 mmol), triphenylphosphine (113 mg, 0.375 mmol) and
diethylazodicarboxylate (0.06 ml, 0.375 mmol) were dissolved in
a small volume of dry THF (0.2 ml) under argon and the reaction
mixture was stirred at room temperature for 4 h (3 days in the case
of cholesterol and stigmasterol). Evaporation to dryness and flash
chromatography (silica gel/dichloromethane) afforded compounds
3aec and 4a,b.
d
8.25 (d, J ¼ 8.8 Hz, 2H, C6H4). 7.66 (d. J ¼ 8.8 Hz, 2H, C6H4), 5.02 (s,
2H, CH2Ph), 4.68 (t, J ¼ 1.9 Hz, 2H, C5H4), 4.43 (t, J ¼ 1.9 Hz, 2H,
C5H4), 4.10 (q, J ¼ 7.1 Hz, 2H, CH2CH3), 3.98 (s, 5H, Cp), 1.06 (t,
J ¼ 7.2 Hz, 3H, CH2CH3). 13C NMR (50 MHz, CDCl3):
d 171.3 (CO),
155.4 (CO), 147.3 (C6H4), 145.4 (C6H4), 128.9 (C6H4), 123.6 (C6H4),
76.8, 70.8, 70.4, 70.2 (ferrocenyl), 63.0 (CH2), 48.4 (CH2), 13.7 (CH3).
IR (CHCl 3, cmꢀ1): 1727 (CO), 1676 (C]O), 1522, 1347 (NO2). Anal.
Calcd for C21H20FeN2O5: C, 57.79; H, 4.62; N, 6.42. Found: C, 57.62;
H, 4.60; N, 7.04. 4a: Yield 56%. Orange solid. 1H NMR (700 MHz
3a Yield 41%. Red oil.1H NMR (200 MHz, CDCl3):
d 7.28e7.41 (m,
5H, Ph), 4.94 (s, 2H, CH2Ph), 4.62 (t, J ¼ 1.8 Hz, 2H, C5H4), 4.36 (t,
J ¼ 1.8 Hz, 2H, C5H4), 4.10 (q, J ¼ 7.1 Hz, 2H, CH2CH3), 3.86 (s, 5H, Cp),
CDCl3):
d
5.42 (m, 1H), 5.12 (quintet, J ¼ 2.8 Hz, 1H), 4.61 (m, 1H,
1.06 (t, J ¼ 7.2 Hz, 3H, CH2CH3). 13C NMR (50 MHz, CDCl3,
d
): 175.0
C5H4), 4.58 (m, 1H, C5H4), 4.34 (m, 2H, C5H4), 4.23 (quartet,
J ¼ 7.3 Hz, 2H, CH2CH3), 4.21 (s, 5H, Cp), 2.50 (m, 2H), 2.04e1.97 (m,
2H), 1.86e1.71 (m, 4H), 1.70e1.40 (m, 8H), 1.38e1.26 (m, 8H),
1.20e1.01 (m, 12H), 0.94e0.85 (m, 10H), 0.70 (m, 3H). 13C NMR
(CO). 155.9 (CO), 137.9 (Ph), 128.6 (Ph), 128.4 (Ph), 127.7 (Ph), 70.5,
70.3, 70.2 (ferrocenyl), 62.7 (CH2), 49.0 (CH2), 13.8 (CH3). IR (CHCl3.
cmꢀ1):1720 (CO). 1668 (C]O).MS e EI (m/z): 391(Mþ). HRMS: m/
z ¼ 391.087115. Calcd for C21H21FeNO3 391.087083. Anal. Calcd for
(175 MHz, CDCl3):
d 163.5 (C]N), 161.2(C]O), 138.8 (C]C), 122.4
C
21H21FeNO3: C 64.47, H, 5.41, N, 3.58. Found: C, 64.51, H, 5.39, N,
(C]C), 72.5, 70.8, 70.2, 69.8, 68.8, 62.1, 56.8, 50.6, 42.3, 39.8, 39.5,
37.1, 36.2, 35.8, 34.1, 32.0, 31.9, 28.2, 28.0, 26.3, 24.3, 23.8, 22.8, 22.6,
20.8,19.1, 18.8,14.4,11.9, IR (CHCl3. cmꢀ1):1699,1651. Anal. Calcd for
3.60. 3b: Red oil. Yield 49%.1H NMR (200 MHz, CDCl3):
d 7.67 (d,
J ¼ 8.5 Hz, 2H, C6H4), 7.58 (d, J ¼ 8.5 Hz, 2H, C6H4), 4.97 (s, 2H,
CH2Ph), 4.66 (t, J ¼ 1.9 Hz, 2H, C5H4), 4.42 (t, J ¼ 1.9 Hz, 2H, C5H4),
4.09 (q, J ¼ 7.1 Hz, 2H, CH2CH3), 3.97 (s, 5H, Cp), 1.06 (t. J ¼ 7.2 Hz,
C
41H59FeNO3:C, 73.52, H, 8.88, N, 2.09. Found: C, 73.48, H, 8.79, N,
2.15. 4b.Yield 48%. Orange solid. 1H NMR (600 MHz CDCl3):
d
5.42
3H, CH2CH3).13C NMR (50 MHz, CDCl3):
d
174.9 (CO), 155.3 (CO),
(m, 1H), 5.18 (dd, J1 ¼ 8.69 Hz, J2 ¼ 15.08 Hz, 1H), 5.13 (quintet,
J ¼ 2.7 Hz, 1H), 5.04 (dd, J1 ¼8.69 Hz, J2 ¼ 15.04 Hz,1H), 4.62 (m, 1H,
C5H4), 4.59 (m, 1H, C5H4), 4.35 (m, 2H, C5H4), 4.24 (quartet,
J ¼ 7.2 Hz, 2H, CH2CH3), 4.22 (s, 5H, Cp), 2.50 (qt, J1 ¼ 23.8 Hz,
J2 ¼ 2.6 Hz, 2H), 2.04e2.00 (m, 3H), 1.98e1.93 (m, 1H), 1.84e1.68
(m, 4H), 1.64e1.49 (m, 8H), 1.45e1.40 (m, 1H),1.34 (t, J ¼ 7.2 Hz, 3H),
1.30e1.22 (m, 2H), 1.21e1.10 (m, 4H), 1.08 (s, 3H), 1.05 (d, J ¼ 6.7 Hz,
3H), 0.86 (d, J ¼ 6.4 Hz, 3H), 0.82 (t, J ¼ 7.4 Hz, 3H), 0.81 (d,
143.3 (C6H4), 132.3 (C6H4), 128.9 (C6H4), 118.6 (C6H4), 111.5 (CN),
76.9, 70.8, 70.4, 70.3 (ferrocenyl), 63.1 (CH2), 48.4 (CH2), 13.8 (CH3).
J ¼ 6.4 Hz, 3H), 0,74 (s, 3H). 13C NMR (175 MHz, CDCl3):
d 163.5 (C]
N), 161.2(C]O), 138.9(C]C), 138.3 (C]C), 129.3 (C]C), 122.3 (C]
C), 72.4, 70.8, 70.2, 69.8, 68.8, 62.1, 56.9, 56.1, 51.2, 50.7, 42.3, 40.4,
39.7, 37.1, 36.1, 34.1, 32.0, 31.9, 31.8, 28.9, 26.3, 25.4, 24.3, 21.3, 21.1,
20.9, 19.1, 18.9, 14.4, 12.2, 12.1. IR (CHCl3. cmꢀ1):1713, 1660. Anal.
Calcd for C43H61FeNO3: C, 74.23, H, 8.84, N, 2.01. Found: C, 74.16, H,
8.95, N, 1.98.
+
2
H
Cl / MeOH
-H2O
4 a
reflux
HO
5
Fig. 1. The signal of H-3 in the 1H NMR spectrum of 4a (700 MHz, CDCl3).
Scheme 5. Hydrolysis of 4a.

A. Wrona-Piotrowicz et al. / Journal of Organometallic Chemistry 696 (2011) 3826e3830
3829
Table 1
-
N
OEt
N
OEt
Selected geometric parameters (Å, ꢁ) for 3b.
N
OEt
Fe
Fe
-
Fe
-
X
O
X
O
X
O
Fe1eC1A
2.033 (2)
O1eC6
1.216 (2)
Fe1eC1B
Fe1eC2A
Fe1eC2B
Fe1eC3A
Fe1eC3B
Fe1eC4A
Fe1eC4B
Fe1eC5A
Fe1eC5B
2.043 (2)
2.036 (2)
2.044 (2)
2.055 (2)
2.040 (2)
2.059 (2)
2.046 (3)
2.044 (2)
2.044 (2)
O2eN2
O3eN2
O21eC21
O22eC21
O22eC22
N1eC6
N1eC7
N1eC21
N2eC11
1.234 (3)
1.225 (3)
1.210 (2)
1.329 (2)
1.462 (2)
1.419 (2)
1.476 (2)
1.393 (2)
1.477 (3)
Fig. 2. Mesomeric structures of the anion of 1 (X ¼ S) and 2 (X ¼ O).
4.3. Hydrolysis of 4a
A solution of 4a (80 mg, 0.12 mmol) in MeOH (10 ml) and 2M aq.
HCl (2 ml) was refluxed for 4 h. After cooling to room temperature
the reaction mixture was poured into water (10 ml) and extracted
several times with CH2Cl2. Flash chromatography (CH2Cl2/MeOH
95:5) afforded 5 as a white powder (40 mg, 89%) followed by 2
(29 mg, 83%). Analytical data for 5: mp 139e141 ꢁC (Lit. 141e142 ꢁC)
C21eO22eC22
C6eN1eC7
114.91 (12)
116.87 (13)
123.17 (13)
117.92 (14)
124.3 (2)
117.6 (2)
118.2 (2)
119.48 (17)
123.63 (16)
N1eC6eC1A
N1eC7eC8
116.69 (15)
112.39 (17)
119.0 (2)
C6eN1eC21
C7eN1eC21
O2eN2eO3
O2eN2eC11
O3eN2eC11
O1eC6eN1
O1eC6eC1A
N2eC11eC10
N2eC11eC12
O21eC21eO22
O21eC21eN1
O22eC21eN1
O22eC22eC23
[13]. 1H NMR (200 MHz, CDCl3):
d 5.42 (m, 1H), 4.01 (m, 1H, C3b-H);
118.7 (2)
125.94 (15)
122.94 (15)
111.03 (13)
106.50 (13)
MS (EI) 386 (Mþ), identical with literature data [13,14].
4.4. X-ray diffraction analysis
The crystals were mounted on glass fibers and then flash-
frozen to 100 K (Oxford Cryosystem-Cryostream Cooler). Prelim-
inary examination and intensities data collections were carried
by R.C. Clark & J.S. Comput. Phys. Commun. (1998). 111, 243. The
structures were solved by direct methods and refined by the full-
matrix least-squares method on all F2 data using the SHELXTL
software [15]. Carbon bonded hydrogen atoms were included in
calculated positions and refined in the riding mode using SHELXTL
default parameters. Other hydrogen atoms were located in
a difference map. Crystal and structure refinement data are
collected in Table 2.
out on a Kuma KM4CCD
k-axis diffractometer with graphite-
monochromated MoKa radiation [14]. The data were corrected
for Lorentz, polarization and absorption effects. Absorption
correction: analytical CrysAlis CCD. Version 1.171.31 (Oxford
Diffraction Ltd., 2006). Analytical numeric absorption correction
using a multifaceted crystal model based on expressions derived
Table 2
Crystal and structure refinement data for 3b
3b
Crystal data
Formula
C21H20FeN2O5
Crystal description
Block, red
Crystal size
Mr
Dx
Space group
Z
0.21 ꢂ 0.18 ꢂ 0.15 mm
436.24
1.479 Mg mꢀ3
Monoclinic, C2/c
8
a
b
c
b
26.679 (6) Å
7.933 (5) Å
22.326 (6) Å
123.96 (2)ꢁ
3919 (3) Å3
V
Data collection
Diffractometer
Kuma KM-4 CCD kappa-axis diffractometer
Radiation type
m
Mo Ka
0.81 mmꢀ1
T
100 (2) K
u
scans
4478 independent reflections,
3274 reflections with I > 2s(I),
16814 measured reflections
Rint
Tmin
Tmax
qmax
0.033
0.842.
0.871.
27.5ꢁ
Refinement
Refinement on F2
R[F2 > 2
0.077
1.04
s
(F2)] ¼ 0.030
wR(F2)
S
Number of parameters
H-atom parameters
constrained
263
1/[
s
2(F2o) þ (0.043P)2] where P ¼ (Fo2 þ 2F2c)/3
w
(
D
/
s
)
0.002
max
Drmax
Drmin
Extinction correction
0.38 e Åꢀ3
ꢀ0.24 e Åꢀ3
None.
Fig. 3. The molecular structure of 3b. Thermal ellipsoids are shown at the 50% prob-
ability level.

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A. Wrona-Piotrowicz et al. / Journal of Organometallic Chemistry 696 (2011) 3826e3830
[3] R. Dembinski, Eur. J. Org. Chem. (2004) 2763e2772.
Acknowledgment
[4] S. Dandapani, D.P. Curran, Chem. Eur. J. 10 (2004) 3130e3138.
[5] B. Long, S. Liang, D. Xin, Y. Yang, J. Xiang, Eur. J. Med. Chem. 44 (2009)
2572e2576.
Financial support from the Ministry of Science and Higher
[6] A.N. Patwa, S. Gupta, R.G. Gonnade, V.A. Kumar, M.M. Bhadbhade, K.N. Ganesh,
J. Org. Chem. 73 (2008) 1508e1515.
[7] A. Jankowiak, M. Jasinski, P. Kaszynski, Inorg. Chim. Acta 360 (2007)
3637e3641.
Education research grant
acknowledged.
N N 204 154636 is gratefully
ꢀ
ꢀ
[8] P. Haquette, M. Salmain, K. Svedlung, M. Martel, B. Rudolf, J. Zakrzewski,
Appendix. Supplementary data
S. Cordier, T. Roisnel, C. Fosse, G. Jaouen, ChemBioChem
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224e231.
CCDC 672311 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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