Synthesis of ferrocene derivatives functionalized with α-methylene- γ-butyrolactone rings Dedicated to Professor Maria Jose? Calhorda on the occasion of her 65th birthday.

Article abstract of DOI:10.1016/j.jorganchem.2014.01.032

This work reports the synthesis and characterization of new ferrocene derivatives functionalized with one or two α-methylene-γ- butyrolactone rings. These compounds were prepared via Reformatsky-type reaction between carbonyl ferrocene derivatives and eth

Full text of DOI:10.1016/j.jorganchem.2014.01.032

Journal of Organometallic Chemistry 760 (2014) 19e23
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis of ferrocene derivatives functionalized with
butyrolactone rings
a
-methylene-g-
,
a
b
Carlos Anjo a, J. Albertino Figueiredo a , M. Isabel Ismael , Ivânia Cabrita ,
**
,
Ana C. Fernandes b
*
a Textile and Paper Materials Unity, University of Beira Interior, Rua Marquês d’Ávila e Bolama, 6201-001 Covilhã, Portugal
b Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
a r t i c l e i n f o
a b s t r a c t
Article history:
This work reports the synthesis and characterization of new ferrocene derivatives functionalized with
one or two -methylene- -butyrolactone rings. These compounds were prepared via Reformatsky-type
reaction between carbonyl ferrocene derivatives and ethyl 2-bromomethylacrylate in 33e85% yields.
Ó 2014 Elsevier B.V. All rights reserved.
Received 3 October 2013
Received in revised form
27 January 2014
a
g
Accepted 28 January 2014
Dedicated to Professor Maria José Calhorda
on the occasion of her 65th birthday.
Keywords:
Ferrocene derivatives
a
-Methylene-g-butyrolactone
Reformatsky-type reaction
1. Introduction
communication we explored the preparation of ferrocene de-
rivatives functionalized with a-methylene-g-butyrolactone rings.
In last past years there has been an increasing interest in the
design of new compounds incorporating the ferrocene skeleton [1e
12], due to its easy chemical modification, small size, relative lip-
ophilicity, and stability in aqueous and aerobic media. Several ex-
amples of ferrocene derivatives incorporated a drug moiety such as
antibiotics (penicillin or cephalosporins) [13] and cancer drugs
(tamoxifen) [14] have also been synthesized.
2. Results and discussion
The synthesis of ferrocene derivatives functionalized with
a-
methylene- -butyrolactone rings was carried out by Reformatsky-
g
type reaction between a carbonyl ferrocene derivative and ethyl
2-bromomethylacrylate with zinc as catalyst (Scheme 1).
a
-Methylene-g-butyrolactones are versatile structural units
present in various important natural products which exhibit
interesting biological activities such as antimicrobial [15] and
antitumoral [16]. Several method have been developed for the
2.1. Synthesis of starting materials
The Reformatsky-type reaction was initially explored from the
commercial available substrates ferrocenecarboxaldehyde 1, ace-
tylferrocene 2, and 1,10-diacetylferrocene 3. The substrates 4 and 5
were prepared by FriedeleCrafts acylation reacting ferrocene with
(4-chlorophenyl)acetyl chloride or with octanoyl chloride, using
the method described by Wang et al. [23] (Scheme 2).
The structure of compounds 4 and 5 was confirmed by NMR
spectroscopy, where new signals from the carbon chain attached to
the Cp ring of ferrocene were detected. In the 1H NMR spectrum of
preparation of a-methylene-g-lactones [17e20], among which the
Reformatsky-type reaction. In our group, this structural unity was
introduced in different positions of sugar derivatives, using the
Reformatsky-type reaction [21].
In continuation of our work about the synthesis of molecules
containing
a-methylene-g-lactone rings [21,22], in this
4 were observed two doublets at
sponding to the aromatic ring of the chlorobenzyl group and a
singlet at 3.96 ppm belonging to the CH2. Formation of 4 was also
confirmed by the analysis of its 13C NMR spectrum, which showed
d 7.26 and 7.07 ppm, corre-
* Corresponding author. Tel.: þ351 218419264; fax: þ351 218464457.
** Corresponding author. Tel.: þ351 275319778; fax: þ351 275319730.
E-mail addresses: albfig@ubi.pt (J. Albertino Figueiredo), anacristinafernandes@
tecnico.ulisboa.pt (A.C. Fernandes).
d
0022-328X/$ e see front matter Ó 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2014.01.032

20
C. Anjo et al. / Journal of Organometallic Chemistry 760 (2014) 19e23
Scheme 3. Preparation of compound 6 using Wittig reaction conditions.
Scheme 1. Synthesis of ferrocene derivatives functionalized with
a-methylene-g-
butyrolactone rings.
d
81.4e84.4 ppm as quaternary carbons, whereas for compound 7,
C-5 appears at
d 75.6 ppm (CH). Finally, the CH2 group (C-4) of
the signal of the carbonyl group at
aromatic ring at 133.4, 132.6, 130.7, 128.6 ppm and the CH2 group
at 45.8 ppm.
The carbon chain of compound 5 appears in the 1H NMR spec-
trum as two multiplets at 1.72e1.65 ppm and 1.34e1.29 ppm and
2.68 and 0.87 ppm. The carbonyl group was
d 201.6 ppm, the signals of the
lactone rings is observed at 34.5e41.9 ppm. Compound 9 has some
signals duplicated in 13C NMR spectrum due to the presence of two
lactone rings. Mass spectrometry studies are concordant with the
structures of the ferrocene derivatives 7e12.
d
d
d
as two triplets at
d
3. Conclusion
visible in the 13C NMR spectrum at
introduction of the carbon chain.
d 204.8 ppm, which confirms the
In conclusion, we have synthesized and characterized six novel
ferrocene derivatives functionalized with
olactone by Reformatsky-type reaction in 33e85% yields. These
kinds of ferrocene derivatives can serve as potential candidates for
biological screening. The synthesis of a variety of other ferrocene
We have also prepared the ferrocene derivative 6 via Wittig
reaction between ferrocenecarboxaldehyde 1 and 1-(triphenyl-
phosphoranylidene)-2-propanone in CH3Cl at reflux temperature
in 80% yield (Scheme 3). In the 1H NMR spectrum of 6 were
a-methylene-g-butyr-
detected two doublets at
constant of J ¼ 16 Hz, confirming the (E)-configuration of the
double bond, and a singlet at 2.30 ppm corresponding to the
methyl group. In the 13C NMR spectrum were identified the
carbonyl group at 197.7 ppm, two signals belonging to the double
bond at 145.0 and 124.1 ppm and the methyl group at 27.1 ppm.
d 7.42 and 6.34 ppm, with a coupling
derivatives containing a a-methylene-g-butyrolactone ring and a
carbohydrate moiety is currently in progress in our laboratory.
d
4. Experimental
d
d
d
4.1. General consideration
2.2. Synthesis of ferrocene derivatives functionalized with
methylene- -butyrolactone rings
a-
Melting points were determined with a melting point apparatus
(Leitz-Biomed) with platinum plate and are uncorrected. IR spectra
g
were recorded in
a Nicolet iS10 with smart iTR spec-
The synthesis of ferrocene derivatives functionalized with
a-
trophotometer.1H NMR spectra were run with a Bruker AC-250P
and Bruker Avance III (400 MHz) spectrometer. Chemical shifts
are expressed in parts per million (ppm) downfield from TMS. The
13C NMR spectra were run at 62.90 and 100.6 MHz in the same
spectrometers. The experiments were performed in chloroform-d.
The progress of all reactions was monitored by thin layer chro-
matography (TLC) using aluminium sheets precoated with silica gel
60 F254 to a thickness of 0.2 mm (Merck). Compounds were
detected with UV light (254 nm) and/or by spraying the sheets with
a 3% vanillin in ethanol/sulfuric acid (100 mL/1.5 mL) followed by
heating. Column chromatography (CC) was conducted under low
pressure by elution of the columns filled with silica gel (0.040e
0.063 mm, Merck). The synthesis of ethyl 2-bromomethylacrylate
[24] and the activation of zinc granules (20 mesh) [25] were car-
ried out according to the techniques reported in the literature. All
other chemicals and solvents used were obtained from commercial
sources and used as received or dried using standard procedures.
methylene- -butyrolactones was carried out from the carbonyl
g
ferrocene derivatives 1e6 via Reformatsky-type reaction with ethyl
2-bromomethylacrylate in the presence of activated granulated
zinc (20 mesh). These reactions were performed in dry THF under
inert atmosphere at 50 ꢀC (Scheme 4). The products 7e12 were
obtained in 33e85% yields after purification by chromatography.
The formation of the lactone derivative in compounds 7e12 was
confirmed by the analysis of their 1H and 13C NMR spectra. The
signals corresponding to the
a-methylene-g-butyrolactones are
reported in Tables 1and 2. Lactones present in 1H NMR spectra
characteristic values for CH2 of ring, assigned as H-4a and H-4b
(Scheme 5), at
at 6.18e6.33 ppm (H-1’a) and at
13C NMR spectra, the signal of the carbonyl group of lactone is
detected at 169.7e170.1 ppm. The quaternary carbon (C-3) of the
double bond appears at
134.9e136.1 ppm and CH2 (C-10) at
121.9e122.5 ppm. C-5 presents signals for compounds 8e12 at
d
2.83e3.34 ppm. The CH2 from double bond appears
d
d
5.57e5.71 ppm (H-10b). In the
d
d
d
4.2. Synthesis of compounds 4e6
Compounds 4 and 5 were prepared according with the method
reported by Wangs [23] by reaction between ferrocene (5 mmol)
and (4-chlorophenyl)acetyl chloride (15 mmol) or octanoyl chloride
(15 mmol) catalyzed by ZnO (6 mmol).
4.2.1. 2-(4-Chlorophenyl)-1-ferrocenylethanone (4)
Scheme 2. Synthesis of ferrocene derivatives 4 and 5 by FriedeleCrafts acylation.

C. Anjo et al. / Journal of Organometallic Chemistry 760 (2014) 19e23
21
Scheme 4. Synthesis of ferrocene derivatives functionalized with a-methylene-g-butyrolactones.
Dark orange solid in yield 85%; m.p. 118e119 ꢀC; 1H NMR (
d
concentration under reduced pressure, the residue was purified by
chromatography eluting with ethyl acetate/cyclohexane (1:4) to
give 6 as dark orange solid in 80% yield (1.85 g). m. p. 84e85 ꢀC; IR
ppm, J Hz, CDCl3): 7.26 (d, 2H, J ¼ 7.9 Hz, H-Ph), 7.07 (d, 2H,
J ¼ 7.9 Hz, H-Ph), 4.82 (s, 2H, H ferrocene), 4.54 (s, 2H, H ferrocene)
4.13 (s, 5H, H ferrocene), 3.96 (s, 2H CH2); 13C NMR (
d
ppm, J Hz,
(ATR, cmꢁ1): 1662, 1637 cmꢁ1; 1H NMR (
d
ppm, J Hz, CDCl3): 7.42 (d,
1H, J ¼ 16 Hz, H-3), 6.34 (d, 1H, J ¼ 16 Hz, H-4), 4.51, 4.45 (2s, 4H, H
ferrocene), 4.16 (s, 5H, H ferrocene), 2.30 (s, 3H, CH3CO); 13C NMR (
CDCl3): 201.6 (C]O), 133.4 (C of Ph), 132.6 (C of Ph), 130.7 (2 CH of
Ph), 128.6 (2CH of Ph), 74.2 (C-1 ferrocene), 72.6-69.7 (CH ferro-
cene), 45.8 (CH2-Ph).
d
ppm, CDCl3): 197.7 (C-2), 145.0 (C-3), 124.1 (C-4), 78.1 (C-1 ferro-
cene), 70.0e69.6 (CH ferrocene), 27.1 (CH3CO).
4.2.2. 1-Ferrocenyloctan-1-one (5)
4.3. General procedure for the synthesis of ferrocene derivatives
functionalized with
a-methylene-g-butyrolactone 7e12 [21]
A
solution of ethyl 2-bromomethylacrylate (5 mmol) in
anhydrous THF (2.5 mL) was added to a mixture containing the
carbonyl compound (3 mmol) in anhydrous THF (1.2 mL) and
activated granulated zinc 20 mesh (1.23 mmol) at room temper-
ature under inert atmosphere. The reaction mixture was heated at
50 ꢀC during 3e5 h. After cooling to room temperature, a hy-
drochloric acid solution (10%, 25 mL), cooled at 0 ꢀC, was added.
Then, the reaction mixture was extracted with dichloromethane
(3 ꢂ 15 mL), the organic phase was neutralized with a solution of
sodium hydrogen carbonate (2.5%, 25 mL) and dried with anhy-
drous sodium sulphate. After evaporation of the solvent, the
residue was purified by chromatography (ethyl acetate/cyclo-
hexane 1:10).
Orange oil, yield 83%; IR (ATR, cmꢁ1): 1669 cmꢁ1 1H NMR (
; d
ppm, J Hz, CDCl3): 4.77 (s, 2H, H ferrocene), 4.47 (s, 2H, H ferrocene),
4.18 (s, 5H, H ferrocene), 2.68 (t, 2H, J ¼ 7.5 Hz, CH2-2),1.72e1.65 (m,
2H, CH2-3), 1.34e1.29 (m, 8H, CH2-4-7), 0.87 (t, 3H, CH3-8,
J ¼ 6.6 Hz); 13C NMR (
d ppm, CDCl3): 204.8 (C]O), 72.2 (C-1
ferrocene), 69.8e69.4 (CH ferrocene), 39.8 (CH2-2), 31.8, 29.6, 29.3,
24.7, 22.7 (CH2-3-7), 14.2 (CH3-8).
4.2.3. 4-Ferrocenylbut-3-en-2-one (6)
4.3.1. 5-Ferrocenyl-3-methylene-1,4-lactone (7)
A solution of ferrocenecarboxaldehyde 1 (1.54 g, 7.2 mmol) in
chloroform (35 mL) was added to a solution of 1-(triphenylphos-
phoranylidene)-2-propanone (4.64 g, 14.6 mmol) in chloroform
(35 mL). The mixture was stirred at reflux during 1 h. After
Table 1
Table 2
Lactone rings signals of compounds 7e12 in the 1H NMR spectra.
Lactone rings signals of compounds 7e12 in the 13C NMR spectra.
H-10a
H-10b
H-4a
H-4b
H-5
C-2
C-3
C-10
C-5
C-4
7
8
9
6.28 (dd) 5.70 (dd) 3.34e3.26 (m) 3.06e2.99 (m) 5.36e5.31 (m)
7
8
9
10
11
12
170.1
169.7
169.7
169.7
170.0
169.8
134.9
136.0
135.8, 135.7
135.3
136.1
121.9
122.0
122.5, 122.4
122.2
122.1
75.6 (CH)
82.2
82.2
83.7
84.4
34.5
41.9
41.8
38.3
39.3
40.8
6.29 (dd) 5.67 (dd) 3.23 (dt)
6.31 (s) 5.71 (s) 3.24 (d)
2.96 (dt)
2.97 (d)
3.07 (dt)
3.04 (d)
2.83 (dt)
1.70 (s, CH3-5)
1.69 (s, CH3-5)
10 6.18 (dd) 5.57 (dd) 3.25 (dt)
11 6.33 (s) 5.71 (s) 3.27 (d)
12 6.23 (dd) 5.64 (dd) 2.95 (dt)
e
e
1.57 (s, CH3-5)
135.3
122.2
81.4

22
C. Anjo et al. / Journal of Organometallic Chemistry 760 (2014) 19e23
(C-10), 122.4 (C-10), 94.6 (C-1 ferrocene), 94.5 (C-1 ferrocene), 82.2
(C-5), 69.4e66.0 (CH ferrocene), 41.8 (C-4), 29.2 (C-50); ESI(þ)-
HRMS: found 406.08563 (406.08622 calcd for C22H22O4Fe).
4.3.4. 5-Ferrocenyl-5-(4-chlorobenzyl)-3-methylene-1,4-lactone
(10)
Scheme 5. Assignment of proton and carbon of synthesized lactones (Fc ¼ ferrocenyl).
Yellow solid, yield 59% (0.50 g); m.p.135e139 ꢀC; IR (ATR, cmꢁ1):
1746, 1660 cmꢁ1; 1H NMR (
d
ppm, J Hz, CDCl3): 6.28 (dd, 1H, JH-1 a,H-
0
¼ 2.5 Hz, JH-1 a,H-4b ¼ 5.5 Hz, H-10a), 5.70 (dd, 1H, JH-1 b,H-
0
0
4a
¼ 2.3 Hz, JH-1 b,H-4b ¼ 4.7 Hz, H-10b), 5.36e5.31 (m, 1H, H-5), 4.26
0
4a
(s, 3H, H ferrocene), 4.23 (s, 6H, H ferrocene), 3.34e3.26 (m, 1H, H-
4a), 3.06e2.99 (m, 1H, H-4b); 13C NMR (
d ppm, CDCl3): 170.1 (C-2),
134.9 (C-3), 121.9 (C-10), 86.5 (C-1 ferrocene), 75.6 (C-5), 68.8e66.1
(CH ferrocene), 34.5 (C-4); ESI(þ)-HRMS: found 282.03450
(282.03377 calcd for C15H14O2Fe).
Light green solid, yield 85% (1.03 g); m.p. 149e151 ꢀC; IR (ATR,
cmꢁ1): 1743, 1665 cmꢁ1
;
1H NMR (
d
ppm, J Hz, CDCl3): 7.18 (d, 2H,
0
J ¼ 8.30 Hz, H-Ph), 6.93 (d, 2H, J ¼ 8.30 Hz, H-Ph), 6.18 (dd,1H, JH-1 a,H-
¼ 2.9 Hz, JH-1 a,H-4b ¼ 5.8Hz, H-10a), 5.57 (dd,1H, JH-1 b,H-4b ¼2.6 Hz,
0
0
4.3.2. 5-Ferrocenyl-5-methyl-3-methylene-1,4-lactone (8)
4a
JH-1 b,H-4a ¼ 5.1 Hz, H-10b), 4.21e3.90 (m, 9H, H ferrocene), 3.25 (dt,
0
0
0
1H, JH-1 a,H-4a ¼ 2.9 Hz, JH-1 b,H-4a ¼ 5.1 Hz, H-4a), 3.13 (d,1H, J ¼ 13.8,
CH200), 3.07 (dt,1H, JH-1 a,H-4b ¼ 5.8 Hz, JH-1 b,H-4b ¼ 2.6 Hz, H-4b), 2.95
0
0
(d,1H, J ¼ 13.8, CH200); 13C NMR (
d ppm, CDCl3): 169.7 (C-2),135.3 (C-
3),133.3 (C of Ph),133.0 (C of Ph),132.2 (2CH of Ph),128.3 (2CH of Ph),
122.2 (C-10), 93.7 (C-1 ferrocene), 83.7 (C-5), 68.8e66.1 (CH ferro-
cene), 48.3 (CH2-Ph), 38.3 (C-4); ESI(þ)-HRMS: found 406.04229
(406.04181 calcd for C22H19O2ClFe).
4.3.5. 5-Ferrocenyl-5-heptyl-3-methylene-1,4-lactone (11)
Light orange solid, yield 70% (0.67 g); m.p. 73e75 ꢀC; IR (ATR,
cmꢁ1): 1743, 1661 cmꢁ1; 1H NMR (
d
ppm, J Hz, CDCl3): 6.29 (dd, 1H,
JH-1 a,H-4a ¼ 2.8 Hz, JH-1 a,H-4b ¼ 5.6 Hz, H-10a), 5.67 (dd, 1H, JH-1 b,H-
0
0
0
¼ 2.5 Hz, JH-1 b,H-4a ¼ 5.0 Hz, H-10b), 4.19 (s, 2H, H ferrocene), 4.17
0
4b
0
(s, 2H, H ferrocene), 4.09 (s, 5H, H ferrocene), 3.23 (dt, 1H, JH-1 a,H-
0
0
¼ 2.8 Hz, JH-1 b,H-4a ¼ 5.0 Hz, H-4a), 2.96 (dt, 1H, JH-1 a,H-
4a
¼ 5.6 Hz, JH-1 b,H-4b ¼ 2.5 Hz, H-4b), 1.70 (s, 3H, CH3-5); 13C NMR
0
4b
(d
ppm, CDCl3): 169.7 (C-2), 136.0 (C-3), 122.0 (C-10), 93.3 (C-1
ferrocene), 82.2 (C-5), 68.8e65.3 (CH ferrocene), 41.9 (C-4), 29.0 (C-
50); ESI(þ)-HRMS: found 296.04977 (296.04942 calcd for
C
16H16O2Fe).
4.3.3. 5,50-(Ferrocenyl-1, 10-diyl)bis(5-methyl-3-methylene-1,4-
lactone) (9)
Yellow solid, yield 60% (0.68 g); m.p. 66e67 ꢀC; IR (ATR, cmꢁ1):
1755, 1662 cmꢁ1; 1H NMR ( ppm, J Hz, CDCl3): 6.33 (s, 1H, H-10a),
d
5.71 (s, 1H, H-10b), 4.31e4.01 (s, 9H, H ferrocene), 3.27 (d, 1H,
J ¼ 10.6 Hz, H-4a), 3.04 (d, 1H, J ¼ 10.6 Hz, H-4b), 1.80-1.70 (m, 2H,
CH2-100), 1.21 (brs, 10H, CH2-200-600), 0.85 (t, 3H, J ¼ 4.2 Hz, CH3-700);
13C NMR ( ppm, CDCl3): 170.0 (C-2), 136.1 (C-3), 122.1 (C-10), 94.6
d
(C-1 ferrocene), 84.4 (C-5), 69.1e66.1 (CH ferrocene), 43.4 (C-100),
39.3 (C-4), 31.8, 29.6, 29.1, 23.7, 22.6 (CH2-200-600), 14.1 (CH3-700);
ESI(þ)-HRMS: found 380.14308 (380.14334 calcd for C22H28O2Fe).
4.3.6. 5-(2-Ferrocen-ethenyl)-5-methyl-3-methylene-1,4-lactone
(12)
Yellow solid, yield 35% (0.43 g); m.p.122e125 ꢀC; IR (ATR, cmꢁ1):
1750, 1665 cmꢁ1; 1H NMR ( ppm, J Hz, CDCl3): 6.31 (s, 2H, H-10a),
d
5.71 (s, 2H, H-10b), 4.23 (s, 4H, H ferrocene), 4.10 (s, 4H, H ferrocene),
3.24 (d, 2H, J ¼ 6.8 Hz, H-4a), 2.97 (d, 2H, J ¼ 6.8 Hz, H-4b),1.69 (s, 6H,
CH3-5); 13C NMR (
d ppm, CDCl3): 169.7 (C-2),135.8,135.7 (C-3),122.5

C. Anjo et al. / Journal of Organometallic Chemistry 760 (2014) 19e23
23
Light orange solid, yield 33% (0.32 g); m.p. 84e85 ꢀC; IR (ATR,
[5] T. Itoh, S. Shirakami, N. Ishida, Y. Yamashita, T. Yoshida, H.-S. Kimb, Y. Wataya,
Bioorg. Med. Chem. Lett. 10 (2000) 1657e1659.
cmꢁ1): 1754,1669,1653 cmꢁ1; 1H NMR (
d ppm, J Hz, CDCl3): 6.36 (d,
[6] C. Biot, L. Delhaes, H. Abessolo, O. Dormarle, L.A. Maciejewski, M. Mortuaire,
P. Delcourt, P. Deloron, D. Camus, D. Dive, J.S.J. Brocard, J. Organomet. Chem.
589 (1999) 59e65.
1H, J ¼ 15.6 Hz, H-100), 6.23 (dd, 1H, JH-1 a,H-4a ¼ 2.7 Hz, JH-1 a,H-
0
0
¼ 5.4 Hz, H-10a), 5.83 (d,1H, J ¼ 15.6 Hz, H-200), 5.64 (dd,1H, JH-1 b,H-
0
4b
_
[7] D. Plazuk, J. Zakrzewski, M. Salmain, Org. Biomol. Chem. 9 (2011) 408e417.
¼ 2.4 Hz, JH-1 b,H-4a ¼ 4.7 Hz, H-10b), 4.32 (s, 9H, H ferrocene), 4.23
0
4b
[8] A. Hottin, F. Dubar, A. Steenackers, P. Delannoy, C. Biot, J.-B. Behr, Org. Biomol.
Chem. 10 (2012) 5592e5597.
[9] A.A. Simenela, E.A. Morozovaa, L.V. Snegura, S.I. Zykovaa, V.V. Kachalab,
L.A. Ostrovskayac, N.V. Bluchterovac, M.M. Fominac, Appl. Organomet. Chem.
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1334.
[11] V.S. Sudhir, N.Y.P. Kumar, S. Chandrasekaran, Eur. J. Org. Chem. (2009) 5365e
5372.
0
0
(s, 9H, H ferrocene), 2.95 (dt, 1H, JH-1 a,H-4a ¼ 2.7 Hz, JH-1 b,H-
0
0
¼ 4.7 Hz, H-4a), 2.83 (dt,1H, JH-1 a,H-4b ¼ 5.4 Hz, JH-1 b,H-4b ¼ 2.4 Hz,
4a
H-4b),1.57 (s, 3H, CH3-5); 13C NMR (
d ppm, CDCl3): 169.8 (C-2),135.3
(C-3),128.2,127.0 (C-100, C-200),122.2 (C-10), 82.6 (C-1 ferrocene), 81.4
(C-5), 69.2e66.8 (CH ferrocene), 40.8 (C-4), 27.1 (C-50); ESI(þ)-
HRMS: found 322.06480 (322.06509 calcd for C18H18O2Fe).
[12] A.C. Fernandes, Carlos C. Romão, B. Royo, J. Organomet. Chem. 682 (2003) 14e19.
[13] E.I. Edwards, R. Epton, G. Marr, J. Organomet. Chem. 107 (1976) 351e357.
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Acknowledgement
This research was supported by FCT through projects PTDC/QUI-
QUI/102114/2008 and PEst-OE/QUI/UI0100/2013. C. Anjo and
I. Cabrita (SFRH/BD/74280/2010) thank to FCT for a grant. The
authors thank the Portuguese NMR Network (IST-UTL Center) for
providing access to the NMR facilities and the Portuguese National
Mass Spectrometry Network (REDE/1501/REM/2005) for the ESI
(þ)-HRMS measurements.
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