The synthesis, structural characterization and biological evaluation of novel N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl esters as anticancer agents

Article abstract of DOI:10.1016/j.jorganchem.2017.07.019

A series of N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl esters 4–18 were prepared by coupling para-(ferrocenyl) ethynyl benzoic acid 3 to the amino acids GABA(OMe), GABA(OEt) and the dipeptide esters GlyGly(OMe), GlyGly(OEt), Gly-L-Ala(OMe), Gly-L-Ala(OEt), Gly-D-Ala(OMe), Gly-D-Ala(OEt), Gly-L-Leu(OEt), Gly-L-Phe(OEt), SarGly(OMe), SarGly(OEt), Sar-L-Ala(OEt), L-ProGly(OEt) and L-Pro-L-Ala(OEt) using the standard N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC), 1-hydroxybenzotriazole (HOBt) protocol. All the compounds were fully characterized using a combination of I.R., UV-Vis, ¹H NMR, ¹³C NMR, DEPT-135, ¹H-¹³C COSY (HMQC) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Selected compounds 5, 7, 9, 11, 16, 17 and 18 showed micromolar activity in the H1299 NSCLC cell line, with IC₅₀ values in the range of 3.8–8.3 μM.

Full text of DOI:10.1016/j.jorganchem.2017.07.019

Accepted Manuscript
The synthesis, structural characterization and biological evaluation of novel N-{para-
(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl esters as
anticancer agents
Andy G. Harry, James P. Murphy, Norma O'Donovan, John Crown, Dilip K. Rai, Peter
T.M. Kenny
PII:
S0022-328X(17)30448-5
10.1016/j.jorganchem.2017.07.019
JOM 20033
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 14 June 2017
Revised Date: 11 July 2017
Accepted Date: 13 July 2017
Please cite this article as: A.G. Harry, J.P. Murphy, N. O'Donovan, J. Crown, D.K. Rai, P.T.M. Kenny,
The synthesis, structural characterization and biological evaluation of novel N-{para-(ferrocenyl)
ethynyl benzoyl} amino acid and dipeptide methyl and ethyl esters as anticancer agents, Journal of
Organometallic Chemistry (2017), doi: 10.1016/j.jorganchem.2017.07.019.
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ACCEPTED MANUSCRIPT
O
HN
Fe
O
HN
O
O
9

ACCEPTED MANUSCRIPT
The synthesis, structural characterization and biological evaluation of novel
N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl
esters as anticancer agents.
a
b
b
c
Andy G. Harry , James P. Murphy , Norma O'Donovan , John Crown , Dilip K.
d
a,b*
Rai , Peter T. M. Kenny
a
School of Chemical Sciences, Dublin City University, Dublin 9, Ireland
b
National Institiute for Cellular Biotechnology, Dublin City University, Dublin 9,
Ireland
c
Dept. Of Medical Oncology, St. Vincent’s University Hospital, Dublin 4, Ireland.
d
Dept. of Food Biosciences, Teagasc Food Research Centre, Ashtown, Dublin 15
Ireland.
Abstract
A series of N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl
and ethyl esters 4-18 were prepared by coupling para-(ferrocenyl) ethynyl benzoic
acid 3 to the amino acids GABA(OMe), GABA(OEt) and the dipeptide esters
GlyGly(OMe), GlyGly(OEt), Gly-L-Ala(OMe), Gly-L-Ala(OEt), Gly-D-Ala(OMe),
Gly-D-Ala(OEt), Gly-L-Leu(OEt), Gly-L-Phe(OEt), SarGly(OMe), SarGly(OEt), Sar-
L-Ala(OEt), L-ProGly(OEt) and L-Pro-L-Ala(OEt) using the standard N-(3-
dimethylaminopropyl)-N’-ethylcarbodiimide
hydrochloride
(EDC),
1-
hydroxybenzotriazole (HOBt) protocol. All the compounds were fully characterized
1
13
1
13
using a combination of I.R., UV-Vis, H NMR, C NMR, DEPT-135, H- C COSY
HMQC) spectroscopy and electrospray ionization mass spectrometry (ESI-MS).
(
Selected compounds 5, 7, 9, 11, 16, 17 and 18 showed micromolar activity in the
H1299 NSCLC cell line, with IC values in the range of 3.8 to 8.3 µM.
5
0
Keywords : Ferrocene; Bioorganometallic chemistry; Dipeptides; Cytotoxicity; Lung
cancer.
*
Corresponding Author
Dr. Peter T. M. Kenny,
School of Chemical Sciences,
Dublin City University,
Dublin 9, Ireland.
Phone: +353 1 7005689
e-mail: peter.kenny@dcu.ie

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1
. Introduction
Organometallic compounds are versatile species due to the range of both structure and
bonding modes that are accessible. Ferrocene has shown great promise in the area of
medicinal organometallic chemistry due to its aromatic character, redox properties and
low toxicity [1-5]. In particular the reversible redox properties of ferrocene have been
strogly associated with its biological activity [6]. Ferricenium salts that are known to
•
inhibit tumor growth have been shown to produce hydroxyl (HO ) radicals under
physiological conditions, leading to oxidatively damaged DNA [7]. The catalytic
•
generation of intracellular reactive oxygen species (ROS) such as the HO radical
offers an attractive and alternative method to target and kill cancer cells [8].
The medicinal application of ferrocene derivatives is currently an active area of
research, with countless reports showing their activity in vitro and in vivo against
several diseases including fungal and bacterial infections, human immunodeficiency
virus (HIV) and cancer [9-10]. In addition the preparation of artificial ferrocenyl
nucleosides have been reported [11-12]. Perhaps the most popular and well-
researched application of ferrocene and its derivatives is in the area of cancer research
[
13]. Over the past decade Jaouen and co-workers have comprehensively investigated
the in vitro anti-cancer activity of ferrocifen, a ferrocenyl analogue of tamoxifen, and
various related derivatives. Their most promising drug candidates contain a [3]-
ferrocenophane motif and have a potent in vitro anti-proliferative effect in breast and
prostate cancer cell lines [14-16]. We have reported the anti-proliferative effects of
ferrocenyl benzoyl and ferrocenyl naphthoyl bioconjugates in the H1299 non-small
cell lung cancer (NSCLC) cell line [17-23]. These N-(ferrocenyl)benzoyl and
naphthoyl dipeptide esters consist of three components, namely: (i) an electroactive
core, (ii) a conjugated linker that lowers the oxidation potential of the ferrocene
moiety and (iii) an amino acid or peptide derivative that can interact with other
biomolecules via secondary interactions such as hydrogen bonding. In an effort to
improve the cytotoxicity of these derivatives, we are currently modifying the
conjugated linker moiety and conducting variations of the peptide chain. The
compounds prepared in this study have an ethynyl group linked to the ferrocene and
the benzoyl spacer group.
Herein, we report the synthesis and structural
characterization of novel N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and
dipeptide ethyl esters. The synthesis of the novel ferrocenyl bioconjugates involved

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Sonogashira coupling of ethynyl ferrocene to 4-bromobenzoic acid generating para-
(ferrocenyl) ethynyl benzoic acid [24]. A series of amino acid and dipeptide esters
were coupled to the para-(ferrocenyl) ethynyl benzoic acid furnishing the novel
ferrocenyl bioconjugates which were characterized by a combination of I.R., UV-Vis,
1
13
1
13
H NMR, C NMR, DEPT-135, H- C COSY spectroscopy and electrospray
ionization mass spectrometry. In addition, we present the in vitro anti-cancer activity
of compounds 4-18 against the NSCLC human lung carcinoma cell line H1299.
2
2
2
. Results and Discussion
.1. Synthesis
.1.1. Synthesis of N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide
methyl and ethyl esters 4-18.
para-(Ferrocenyl) ethynyl benzoic acid 3 was prepared by coupling ethynyl ferrocene
1
to 4-bromobenzoic acid via the Sonogashira reaction [24]. In the H NMR spectrum
the benzoyl ring protons appeared as two apparent doublets at δ 7.9 and δ 7.58
respectively with a coupling constant of 9.2 Hz. The carboxylic acid proton was
5
observed as a singlet at δ 12.83. The ferrocenyl ortho and meta protons on the (η -
C H ) ring were present at δ 4.61 and δ 4.38, respectively, and an intense signal
5
4
5
appeared at δ 4.29 for the (η -C H ) ring. The free N-terminal amino acids of
5
5
GABA(OMe) and GABA(OEt) and the dipeptide esters GlyGly(OMe), GlyGly(OEt),
Gly-L-Ala(OMe), Gly-L-Ala(OEt), Gly-D-Ala(OMe), Gly-D-Ala(OEt), Gly-L-
Leu(OEt), Gly-L-Phe(OEt), SarGly(OMe), SarGly(OEt), Sar-L-Ala(OEt), L-
ProGly(OEt) and L-Pro-L-Ala(OEt) were coupled using EDC and HOBt in the
presence of excess triethylamine in dichloromethane (Scheme 1). EDC was used in
preference to the less expensive coupling reagent N,N'-dicyclohexylcarbodiimide
(DCC) as its reaction by-products are easier to remove compared to those of DCC,
namely dicyclohexylurea (DCU). Purification by column chromatography furnished
the pure products in yields of 12-38 % and all compounds gave spectroscopic data in
accordance with the proposed structures. The relatively low yields of the products
obtained under the coupling procedures has been discussed previously [25]. The N-
{
para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl esters
1
13
4
-18 were characterized by a combination of IR, UV-Vis, H NMR, C NMR,
1
13
DEPT-135 and H- C COSY (HMQC) spectroscopy. Electrospray ionization mass

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spectrometry (ESI) in conjunction with tandem mass spectrometry (MS/MS) was also
employed in the analysis.
1
13
2
.2. H and C Spectroscopic analysis
All the proton and carbon chemical shifts for compounds 4-18 were unambiguously
1
13
1
13
assigned by a combination of DEPT-135 and H- C COSY. The H and C NMR
spectra for compounds 4-18 showed peaks in the ferrocene region characteristic of a
monosubstituted ferrocene moiety [26-28]. The protons on the ferrocene rings in the
N-{para-(ferrocenyl) ethynyl benzoyl derivatives, are expected to occur as three
signals between δ 4.61 and δ 3.85. However, these signals usually overlap with the
hydrogen signals of either the methylene groups or the methine groups that may be
present in the amino acid and dipeptide esters. However in the Gly L-Ala ethyl ester
derivative 7 no overlapping is observed, hence, the ortho and meta protons on the
5
cyclopentadiene ring attached to the ethynyl spacer (η -C H -C≡C-) appear as two
5
4
apparent triplets at δ 4.61 and δ 4.38 respectively . The protons on the unsubstituted
cyclopentadiene ring appear as a sharp singlet at δ 4.26 as all the hydrogens are
magnetically equivalent. Typical chemical shifts are observed for the N-{para-
(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide esters 4-18 including the
appearance of amide protons and four aromatic hydrogens on the benzoyl spacer
1
moiety between δ 8.91 and δ 6.65. In the H NMR spectra of the Sar Gly 14, 15, Sar-
L-Ala 16, L-Pro Gly 17 and L-Pro-L-Ala 18 dipeptide derivatives, the amide protons
and the aromatic hydrogens on the benzoyl spacer overlap, resulting in multiplets
being observed between δ 7.69 and δ 7.35. For the Gly Gly 6, 7, Gly-L-Ala 8, 9 and
Gly-L-Leu 12 derivatives the splitting pattern of the hydrogens on the benzoyl linker
follows the second order splitting pattern and do not overlap with the amide proton
signals. The methyl protons (-OCH CH ) of the ethyl ester derivatives appear as a
2
3
triplet between δ 1.28 and δ 1.17. The methyl protons (-OCH ) of the methyl esters
3
appear as a sharp singlet between δ 3.70 and δ 3.63.
1
3
In the C NMR spectra of N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and
dipeptide esters 4-18, the typical peaks observed include the appearance of carbonyl
signals between δ 174.4 to δ 165.2. In the amino acid derivatives 4 and 5 only two
carbonyl signals are observed whilst for the dipeptide derivatives 6-18 three carbonyl
signals are observed. These carbonyl signals are absent in the DEPT-135 spectra. In

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the aromatic region of the spectrum four unique carbons signals are observed between
δ 133.8 to δ 125.7. The two quaternary carbon atoms present on the benzoyl spacer
moiety can be easily identified by their absence in the DEPT-135 spectrum and these
signals appear more downfield than the other aromatic carbons in the range δ 133.8 to
5
δ 130.0. The carbons on the -C≡C- linker appear between δ 91.7 to δ 90.6 for (η -
5
C H -C≡C-) and between δ 85.7 to δ 84.1 for (η -C H -C≡C-). These two quaternary
5
4
5
4
carbon atoms are absent in the DEPT-135 spectrum.
5
The ipso carbon on the cyclopentadiene ring (η -C H -C≡C-) attached to the -C≡C-
5
4
unit appears between δ 67.6 to δ 64.6 and is also absent in the DEPT-135 spectra. The
remaining four carbons on the monosubstituted cyclopentadiene rings appear between
5
δ 72.0 to δ 68.0. The ortho carbon atoms on the substituted (η -C H -C≡C-) ring
5
4
5
attached to the ipso carbons, appear more downfield than the meta carbons (η -C H -
5
4
C≡C-) on the substituted cyclopentadiene ring and the unsubstituted ring carbon
signal. This indicates that these carbons have become deshielded by the ethynyl
moiety attached to the cyclopentadiene ring. The five carbon atoms on the
unsubstituted ring give rise to one unique carbon signal because the carbon atoms are
equivalent and appear in the arrow range δ 70.5 to δ 68.8. The methylene carbon of
the ethyl esters (-OCH CH ) appear between δ 62.7 and δ 60.7 whilst the methyl
2
3
carbon appears between δ 14.8 and δ 13.7. In the DEPT-135 spectra the methylene
carbons appear as a negative resonance. Complete spectroscopic data for all the
compounds is presented in the experimental section.
2
.3. Mass Spectrometry
Soft ionization techniques such as electrospray ionization (ESI) and matrix assisted
laser desorption ionization mass spectrometry permit the analysis of thermolabile and
non-volatile analytes [29-30]. The N-{para-(ferrocenyl) ethynyl benzoyl} amino acid
and dipeptide methyl and ethyl esters 4-18 were not amenable to electron ionization
(EI) or chemical ionization (CI) studies, therefore ESI was employed in the analysis of
compounds 4-18. Electrospray ionization (ESI) mass spectrometry confirmed the
correct relative molecular mass for all the compounds. and examination of the mass
spectra revealed the presence of intense radical-cation species. The formation of the
radical-cation molecular ion species was further confirmed by the detection of the
+
+
sodium adducts [M+23] and potassium adducts [M+39] for each of the compounds

ACCEPTED MANUSCRIPT
analyzed. Similar observations were made in the analysis of the related ferrocenyl
ethynyl naphthoyl amino acid and peptide derivatives [25]. Sequence specific
fragment ions were not observed or were of low intensity in the ESI mass spectra of
compounds 4-18 and therefore tandem mass spectrometry was employed to confirm
the integrity of the structures.
In the MS/MS spectrum of N-{para-(ferrocenyl) ethynyl benzoyl} glycine glycine
ethyl ester 7 the sequence specific fragment ions are present at m/z 285, m/z 313, m/z
3
41 and m/z 369 (Fig. 1). The product ions at m/z 285 and m/z 313 correspond to the
N-{para-(ferrocenyl) ethynyl benzyl } and the N-{para-(ferrocenyl) ethynyl benzoyl}
subunits respectively. However, the expected a and b product ions at m/z 342 and
1
1
m/z 370 were not observed, instead a -1 and b -1 product ions were observed at m/z
1
1
3
41 and m/z 369 respectively. The formation of a -1 and b –1 ions in the mass spectra
1 1
of N-{para-(ferrocenyl)benzoyl}-glycine-L-alanine ethyl ester was investigated by
tandem mass spectrometry and deuterium labelling studies. The results showed that
b1-1 product ions arise from the loss of a hydrogen atom attached to the nitrogen and
not to the α-carbon of the glycine residue [31]. The fragment ion at m/z 444
corresponds to loss of C H from the molecular ion via a McLafferty rearrangement
2
4
and is characteristic of these ethyl esters.
2
.4. In vitro anti-cancer activity of 4-18.
The N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide methyl and ethyl
esters 4-18 have been prepared as part of an ongoing SAR study. In a preliminary
screen the in vitro anti-proliferative effect of compounds 4-18 was studied at a
concentration of 10 µM in the H1299 non-small cell lung cancer (NSCLC) cell line.
The results of this biological study are reported in Table 1 and are expressed as
percentage cell growth inhibition relative to the untreated controls. The percentage
cell growth inhibition was lowest for compound 8 at 22 % and highest for compound
9
at 95 % cell growth inhibition. From the preliminary screen at 10 µM a general trend
can be observed, namely, the methyl ester derivatives exhibited lower percentage
growth inhibition values between 22 % to 55 % compared to the ethyl ester
derivatives which exhibited percentage growth inhibition values between 47 % to 95
%. Generally, the lower the percentage growth value, the lower the anti-proliferative
activity. Thus, the methyl ester derivatives were not investigated further. A general

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trend was also observed for the ethyl ester derivatives, that is, the Gly L-Leu and Gly
L-Phe ethyl esters displayed percentage growth inhibition values ≤ 53 %. For instance,
the N-{para-(ferrocenyl) ethynyl benzoyl} glycine L-leucine ethyl ester 12 displayed a
percentage growth inhibition values of 53 % whilst the N-{para-(ferrocenyl) ethynyl
benzoyl} glycine L-phenylalanine ethyl ester 13 displayed a percentage growth
inhibition value of 28 %. Thus, the Gly L-Leu and Gly L-Phe ethyl ester derivatives
were also not investigated further. As a result, it can be concluded that when chiral α-
amino acids with bulky side chains are employed as the second amino acid in the
dipeptide moiety, a loss of anti-proliferative activity is observed. Compounds 5, 7, 9,
1
1, 16, 17 and 18 showed percentage growth inhibition values ≥ 60 %. Therefore, IC50
values were then determined for these compounds by the acid phosphatase assay as
previously described [32]. This colorimetric end-point assay is an indirect measure of
cytotoxicity which evaluates the enzyme activity of cells after a given treatment
period. Acid phosphatase is an enzyme which dephosphorylates p-nitrophenyl
phosphate substrate converting it to p-nitrophenol which in the presence of strong
alkali can be quantified colorimetrically. The cells were treated with the N-{para-
(
ferrocenyl) ethynyl benzoyl} amino acid and dipeptide ethyl esters 5, 7, 9, 11, 16, 17
and 18 at a range of concentrations ( from 1 µM to 100 µM) and were incubated for 5-
days until cell confluency reached 80-90 %. Cell survival was established through
6
determination of the acid phosphatase activity of surviving cells and growth inhibition
calculated relative to controls (untreated cells). The IC values for compounds 5, 7,
5
0
9
, 11, 16, 17 and 18 had IC values in the range of 3.8 to 8.3 µM and are displayed
50
in Table 2. The in vitro cytotoxicity of the platinum(II)-based anti-cancer drugs
cisplatin 19 and carboplatin 20 were also evaluated against the H1299 cell line, and
were found to have an IC values of 1.5 ± 0.1 µM and 10.0 ± 1.6 µM respectively
5
0
(Table 2). Thus, compounds 5, 7, 9, 11, 16, 17 and 18 are less cytotoxic in vitro than
the clinically employed anti-cancer drug cisplatin but more toxic than the clinically
employed anti-cancer drug carboplatin.
It can be seen from Table 2 that the N-{para-(ferrocenyl) ethynyl benzoyl} amino acid
and dipeptide ethyl esters 5, 7, 9, 11, 16, 17 and 18 all exert a cytotoxic effect on the
human lung carcinoma cell line H1299. All seven derivatives have IC values that are
5
0
lower than 8.3 µM. The most active compound was N-{para-(ferrocenyl) ethynyl

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benzoyl} glycine L-alanine ethyl ester 9 which had an IC value of 3.8 µM. Insertion
5
0
of the ethynyl group in compound 9 had a slightly positive effect on the anti-
proliferative effect compared to N-{para-(ferrocenyl)-benzoyl} glycine L-alanine ethyl
ester (IC50 = 6.8 µM) prepared previously by this research group lacking the ethynyl
group [19].
A potential mechanism by which these novel organometallic anticancer compounds
may induce DNA damage is by the catalytic generation of ROS. This is possible via a
•
Fenton-type reaction, in which HO radicals are generated from the superoxide
dismutation product, hydrogen peroxide (H O ). It was shown that the generation of
2
2
8
-oxoGua by a compound prepared in a previous SAR study, namely, N-(6-
ferrocenyl-2-naphthoyl)-glycine-glycine ethyl ester, that the oxidation was occurring
by Fenton chemistry and that N-(6-ferrocenyl-2-naphthoyl)-glycine-glycine ethyl ester
is generating oxidative damage via a ROS-mediated mechanism. Therefore guanine
oxidation studies confirmed that N-(6-ferrocenyl-2-naphthoyl)-glycine-glycine ethyl
ester was capable of causing oxidative damage to guanine, and it does so by the
•
generation of HO radicals from H O [23].
2
2
3
. Conclusions
In conclusion, the novel N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and
dipeptide methyl and ethyl esters 4-18 were synthesized and fully characterized by a
range of NMR spectroscopic techniques and mass spectrometry. Compounds 4-18
were tested in vitro against the NSCLC human lung carcinoma cell line H1299.
Compounds 5, 7, 9, 11, 16, 17 and 18 showed micromolar activity in the H1299
NSCLC cell line, with IC values in the range of 3.8 to 8.3 µM. Insertion of the
5
0
ethynyl group in compound 9 had a slightly positive effect on the anti-proliferative
effect compared to N-{para-(ferrocenyl)-benzoyl} glycine L-alanine ethyl ester (IC50
=
6.8 µM). prepared previously by this research group.
4
. Experimental
4
.1. General Procedures
All chemicals were purchased from Sigma-Aldrich, Lennox Chemicals, Fluorochem
Limited or Tokyo Chemical Industry UK Limited and used as received. Commercial
grade reagents were used without further purification. When necessary, all solvents

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were purified and dried prior to use. Riedel-Haën silica gel was used for thin layer and
column chromatography. Melting points were determined using a Stuart melting point
(SMP3) apparatus and are uncorrected. Optical rotation measurements were made on
-1
2
-1
a Perkin Elmer 343 Polarimeter and are quoted in units of 10 deg cm g . Infrared
spectra were recorded on a Perkin Elmer Spectrum 100 FT-IR with ATR. UV-Vis
spectra were recorded on a Hewlett Packard 8452 A diode array UV-Vis
1
13
spectrophotometer. H and C NMR spectra were recorded in deuterated solvents on
1
13
a Bruker Avance 400 NMR. The H and C NMR chemical shifts are reported in ppm
parts per million). Tetramethylsilane (TMS) or the residual solvent peaks have been
(
used as an internal reference. All coupling constants (J) are in Hertz. Electrospray
ionisation mass spectra were performed on a Micromass LCT mass spectrometer.
TM
Tandem mass spectra were obtained on a Micromass Quattro micro LC-MS/MS triple
quadrupole mass spectrometer.
4
.2. General procedure for the synthesis of the starting materials.
4
.2.1. (2-Formyl-1-chlorovinyl) ferrocene 1
Acetylferrocene (22.8 g, 99.96 mmol) was dissolved in N, N-dimethylformamide (25
ml) at 0 °C under nitrogen. Phosphorus oxychloride (25 ml) was added to
dimethylformamide (25 ml) at 0 °C under nitrogen and stirred for 25 min resulting in
a viscous red complex. The viscous complex was added to the acetylferrocene mixture
over 2 hr and further stirred for 3 hr at 0 °C. Diethyl ether (80 ml), sodium acetate
(116 g, mmol) and deionised water (20 ml) were added to reaction mixture. The
reaction mixture was stirred at room temperature for 12 hr and then conc. sodium
bicarbonate solution was added. The resulting solution was extracted with ethyl
acetate. The solvent was evaporated to yield the crude product which was purified by
column chromatography (eluent 9:1 hexane: diethyl ether) yielding the title compound
3
3
as deep purple crystals. (17 g, 62%), mp. 76 - 77 °C (lit. 76 - 77 °C);
1
H NMR (400 MHz) δ (DMSO- d ): 10.03 (1H, d, J = 7.2 Hz, -CHO), 6.32 {1H, d, J
6
5
5
=
7.2 Hz, η -C H -C=CH(Cl)-}. 4.68 {2H, t, J = 2.0 Hz, ortho on η -C H -C=CH(Cl)-
5 4 5 4
5
5
}
, 4.49 {2H, t, J = 2.0 Hz, meta on η -C H -C=CH(Cl)-}, 4.17 (5H, s, η -C H );
5 4 5 5

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1
3
5
C NMR (100 MHz) δ (DMSO- d ): 190.8 (C=O), 155.4 (η -C H -C=CH(Cl)-),
6
5
4
5
5
5
1
20.4 (η -C H -C=CH(Cl)-), 80.1 (C
η -C H -C=CH(Cl)-), 72.3 (η -C H ), 70.1
ortho 5 4 5 5
5
4
5
5
(
Cmeta η -C H -C=CH(Cl)-), 68.9 (C η -C H -C=CH(Cl)-).
5 4 ipso 5 4
4
.2.2. Ethynyl ferrocene 2
Potassium tert-butoxide (10.24 g, 91.25 mmol) was added to dry tetrahydrofuran (100
ml) at 0 °C under nitrogen and stirred for 25 min. (2-Formyl-1-chlorovinyl) ferrocene
(5 g, 18.25 mmol) was added slowly over 10 min and the reaction mixture was stirred
at 0°C for 30 min and refluxed at 80 °C for 4 hr. The reaction mixture was poured into
ice then neutralised with conc. hydrochloric acid. The resulting solution was extracted
with hexane and the solvent was evaporated to yield the crude product which was
purified by column chromatography (eluent 9:1 hexane: diethyl ether) yielding the
3
1
title compound as a red solid. (1.87 g, 49%) m.p 52 -53 °C, (lit. 52 - 53 °C);
1
5
H NMR (400 MHz) δ (DMSO- d ): 4.68 (2H, t, J = 2.0 Hz, ortho on η -C H -
6
5
4
5
5
C≡CH), 4.25 - 4.15 {7H, m, (meta on η -C H -C≡CH), (η -C H )}, 2.74
5
4
5
5
5
(
1H, s, η -C H -C≡CH);
5 4
1
3
5
5
C NMR (100 MHz) δ (DMSO- d ): 82.5 (η -C H -C≡CH), 73.5 (η -C H -C≡CH),
6
5
4
5
4
5
5
5
7
1.8 (Cortho η -C H -C≡CH), 70.1 (η -C H ), 68.7 (C
η -C H -C≡CH), 63.5 (C
meta 5 4 ipso
5
4
5
5
5
η -C H -C≡CH).
5
4
4
.2.3. para-(Ferrocenyl) ethynyl benzoic acid 3
Ethynyl ferrocene (2.00 g, 9.52 mmol) and 4-bromobenzoic acid (1.91 g, 9.52 mmol)
were mixed together and dissolved in 50 ml of a 1:1 mixture of dry triethylamine and
tetrahydrofuran under nitrogen for 10 min. Triphenylphosphine (0.20 g, 0.76 mmol),
bis(triphenylphosphine)palladium(II) dichloride (0.28 g, 0.38 mmol) and copper(I)
iodide (0.07 g, 0.38 mmol) were mixed together and added to the reaction mixture.
o
The reaction mixture was stirred for 10 min and refluxed at 80 C for 12 hr. The
reaction mixture was vacuum filtered. The solvent was removed in vacuo to yield the
crude product. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) yielding the title compound as a red solid (2.53 g, 81%), mp
o
1
47 - 149 C;

ACCEPTED MANUSCRIPT
1
H NMR (400 MHz) δ (DMSO- d ): 12.83 (1H, s, -COOH), 7.90 (2H, d, J = 9.2 Hz,
6
5
ArH), 7.58 (2H, d, J = 9.2 Hz, ArH), 4.61 (2H, t, J = 2.0 Hz, ortho on η -C H -C≡C-),
5
4
5
5
4
.38 (2H, t, J = 2.0 Hz, meta on η -C H -C≡C-), 4.29 (5H, s, η -C H );
5 4 5 5
1
3
C NMR (100 MHz) δ (DMSO- d ): 171.0 (C=O), 138.2 (C ), 136.1(C ), 133.0,
6
q
q
5
5
5
1
31.0, 96.4 (η -C H -C≡C-), 87.0 (η -C H -C≡C-), 71.4 (C
η -C H -C≡C-), 70.1
ortho 5 4
5
4
5
4
5
5
5
(
η -C H ), 69.7 (C
η -C H -C≡C-), 64.0 (C η -C H -C≡C-).
meta 5 4 ipso 5 4
5
5
General procedure for the preparation of N-{para-(ferrocenyl) ethynyl benzoyl}
amino acids and dipeptide esters
4
.3.1. N-{para-(ferrocenyl) ethynyl benzoyl} γ-aminobutyric acid methyl ester 4
γ-Amino butyric acid methyl ester hydrochloride (0.35 g, 3.03 mmol) was dissolved in
o
dichloromethane (100 ml) at 0 C. N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide
hydrochloride (0.58 g, 3.03 mmol), 1-hydroxybenzotriazole (0.35 g, 3.03 mmol),
glycine glycine methyl ester hydrochloride (0.44 g, 3.03 mmol) and triethylamine (6
o
ml) were added and the reaction mixture was allowed to stir at 0 C for 45 min. The
reaction mixture was then allowed to stir at room temperature for 48 h, and washed
with water and brine. The organic layer was dried over MgSO .. The solvent was
4
removed in vacuo to the crude product was purified by column chromatography
(eluent 1:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate
o
yielded the desired product as a red solid (0.41 g, 32%), m.p 88 - 90 C;
+
Mass spectrum: [M+Na] found: 452.0937
C H NO FeNa requires:
452.0925
2
4
23
3
-1
I.R. υmax (KBr): 3343 (NH), 2207 (-C≡C-), 1731 (C=Oester), 1606 (C=Oamide) cm ;
UV-Vis λmax EtOH: 385, 485 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.76 (2H, d, J = 8.4 Hz, ArH ), 7.55 (2H, d, J = 8.4
3
5
Hz, ArH ), 6.65 (1H, t, J = 4.2 Hz, -CONH-), 4.53 (2H, t, J = 2.0 Hz, ortho on η -
5
5
C H -C≡C-), 4.29 - 4.27 {7H, m, (meta on η -C H -C≡C-), (η -C H )}, 3.70 (3H, s, -
5
4
5
4
5
5
OCH ), 3.54 {2H, q, J = 6.4 Hz, (-NHCH CH CH -)}, 2.49 {2H, t, J = 6.8 Hz, (-
3
2
2
2
NHCH CH CH -)}, 2.00 {2H, quin, J = 6.4 Hz, (-NHCH CH CH -)};
2
2
2
2
2
2
1
3
C NMR (100 MHz) δ (CDCl ): 174.4 (C=O), 166.9 (C=O), 133.0 (C ), 131.4 (C ),
3
q
q
5
5
5
1
7
27.3, 126.9, 91.0 (η -C H -C≡C-), 85.1 (η -C H -C≡C-), 71.6 (C
η -C H -C≡C-),
ortho 5 4
5
4
5
4
5
5
5
0.0 (η -C H ), 69.1 (C
η -C H -C≡C-), 64.8 (C η -C H -C≡C-), 51.9 (-OCH ),
5 4 ipso 5 4 3
5
5
meta

ACCEPTED MANUSCRIPT
3
9.8 (-NHCH CH CH -, -ve DEPT), 31.8 (-NHCH CH CH -, -ve DEPT), 24.3 (-
2
2
2
2
2
2
NHCH CH CH -, -ve DEPT).
2
2
2
4
.3.2. N-{para-(ferrocenyl) ethynyl benzoyl} γ-aminobutyric acid ethyl ester 5
γ-Amino butyric acid ethyl ester hydrochloride (0.40 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.51 g, 38%), m.p 64 - 66 C;
+
Mass spectrum: [M+Na] found: 466.1101
C H NO FeNa requires:
466.1082
2
5
25
3
-1
I.R. υmax (KBr): 3283 (NH), 2205 (-C≡C-), 1726 (C=Oester), 1605 (C=Oamide) cm ;
UV-Vis λmax EtOH: 385, 490 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.73 - 7.67 (4H, m, ArH), 6.65 (1H, t, J = 4.4 Hz, -
3
5
CONH-), 4.55 (2H, t, J = 3.2 Hz, ortho on η -C H -C≡C-), 4.28 (2H, t, J = 3.2 Hz,
5
4
5
5
meta on η -C H -C≡C-), 4.16 (5H, s, η -C H ), 4.07 (2H, q, J = 7.2 Hz, -OCH CH ),
5
4
5
5
2
3
3
.45{2H, q, J = 6.4 Hz, -NHCH CH CH -), 2.38 (2H, t, J = 6.8 Hz, -NHCH CH CH -
2 2 2 2 2 2
)
, 1.91 (2H, quin, J = 6.4 Hz, -NHCH CH CH -), 1.19 ( 3H, t, J= 7.2 Hz, -
2 2 2
OCH CH );
2
3
1
3
C NMR (100 MHz) δ (CDCl ): 173.0 (C=O), 167.0 (C=O), 132.7 (C ), 131.8 (C ),
3
q
q
5
5
5
1
6
27.2, 126.9, 90.8 (η -C H -C≡C-), 85.4 (η -C H -C≡C-), 70.5 (C
η -C H -C≡C-),
ortho 5 4
5
4
5
4
5
5
5
8.8 (η -C H ), 68.2 (C
η -C H -C≡C-), 67.1 (C
η -C H -C≡C-), 60.7 (-
ipso 5 4
5
5
meta
5
4
OCH CH , -ve DEPT), 39.8 (-NHCH CH CH -, -ve DEPT), 32.1 (-NHCH CH CH -,
2
3
2
2
2
2
2
2
-
ve DEPT), 24.3 (-NHCH CH CH -, -ve DEPT), 14.8 (-OCH CH ).
2 2 2 2 3
4
.3.3. N-{para-(ferrocenyl) ethynyl benzoyl} glycine-glycine methyl ester 6
N-para-(ferrocenyl) ethynyl benzoic acid (1.00 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) yielding the title compound as an orange solid (0.35 g, 25%),
o
m.p 169 - 171 C;
+
Mass spectrum: [M+Na] found: 481.0814
C H N O FeNa requires:
481.0827
2
4
22
2
4
I.R. υmax (KBr): 3261 (NH), 2204 (-C≡C-), 1736 (C=Oester), 1658 (C=Oamide), 1603
-1
(
C=Oamide) cm ;

ACCEPTED MANUSCRIPT
UV-Vis λmax EtOH: 385, 490 nm;
1
H NMR (400 MHz) δ (DMSO- d ): 8.91 (1H, t, J = 6.0 Hz, -CONH-), 8.40 (1H, t, J
6
=
6.0 Hz, -CONH-), 7.90 (2H, d, J = 8.0 Hz, ArH), 7.58 (2H, d, J = 8.0 Hz, ArH),
5
5
4
.60 (2H, s, ortho on η -C H -C≡C-), 4.37 (2H, s, meta on η -C H -C≡C-), 4.29 (5H,
5 4 5 4
5
s, η -C H ), 3.93 ( 2H, d, J = 5.6 Hz, -NHCH CO-), 3.86 (2H, d, J = 5.6 Hz, -
5
5
2
NHCH CO-), 3.63 (3H, s, - OCH );
2
3
1
3
C NMR (100 MHz) δ (DMSO- d ): 170.2 (C=O), 168.9 (C=O), 167.8 (C=O), 131.9
6
5
5
(
C ), 130.0 (C ), 127.7, 126.0, 91.2 (η -C H -C≡C-), 84.1 (η -C H -C≡C-), 71.8
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 69.8 (η -C H ), 68.2 (C
η -C H -C≡C-), 64.9 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 51.7 (-OCH ), 48.7, (-NHCH CO-, -ve DEPT), 40.5 (-NHCH CO-, -ve
5
4
3
2
2
DEPT).
.3.4. N-{para-(ferrocenyl) ethynyl benzoyl} glycine glycine ethyl ester 7
4
Glycine glycine ethyl ester hydrochloride (0.48 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.32 g, 22%), m.p 178 - 180 C;
+
Mass spectrum: [M+Na] found: 495.0972
C H N O FeNa requires:
495.0983
2
5
24
2
4
I.R. υmax (KBr): 3261(NH), 2204 (-C≡C-), 1736 (C=Oester), 1658 (C=Oamide), 1603
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 385, 490 nm;
1
H NMR (400 MHz) δ (DMSO- d ): 8.89 (1H, t, J = 6.4 Hz, -CONH-), 8.36 (1H, t, J
6
=
6.4 Hz, -CONH-), 7.90 (2H, d, J = 9.2 Hz, ArH), 7.58 (2H, d, J = 9.2 Hz, ArH),
5
5
4
.61 (2H, t, J = 2.0 Hz, ortho on η -C H -C≡C-), 4.38 (2H, t, J = 2.0 Hz, meta on η -
5 4
5
C H -C≡C-), 4.29 (5H, s, η -C H ), 4.10 (2H, q, J = 7.2 Hz, -OCH CH ), 3.91 (2H, d,
5
4
5
5
2
3
J = 6.0 Hz, -NHCH CO-), 3.84 (2H, d, J = 6.0 Hz, -NHCH CO-), 1.19 (3H, t, J = 7.2
2
2
Hz, - OCH CH );
2
3
1
3
C NMR (100 MHz) δ (DMSO- d ): 170.0 (C=O), 169.3 (C=O), 168.2 (C=O), 132.2
6
5
5
(
C ), 130.7 (C ), 127.7, 126.0, 90.9 (η -C H -C≡C-), 84.3 (η -C H -C≡C-), 72.0
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.5 (η -C H ), 69.1 (C
η -C H -C≡C-), 67.6 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 62.0 (-OCH CH , -ve DEPT), 49.6 (-NHCH CO-, -ve DEPT), 42.3, (-
5
4
2
3
2
NHCH CO-, -ve DEPT), 13.9 (-OCH CH ).
2
2
3

ACCEPTED MANUSCRIPT
4
.3.5. N-{para-(ferrocenyl) ethynyl benzoyl} glycine L-alanine methyl ester 8
Glycine L-alanine methyl ester hydrochloride (0.48 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.25 g, 17%), m.p 112 - 114 C;
2
0
o
[
α]D = -25 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 495.0965
C H N O FeNa requires:
495.0983
2
5
24
2
4
I.R. υmax (KBr): 3336 (NH), 2205 (-C≡C-), 1734 (C=Oester), 1660 (C=Oamide), 1604
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 391, 488 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.73 (2H, d, J = 8.4 Hz, ArH), 7.48 (1H, t, J = 6.8
3
Hz, -CONH-), 7.45 ( 2H, d, J = 8.4 Hz, ArH), 7.33 (1H, d, J = 7.2 Hz, -CONH-), 4.55
5
(
1H, quin, J = 7.2 Hz, -CHCH ), 4.44 (2H, t, J = 2 Hz, ortho on η -C H -C≡C-), 4.21
3
5
4
5
5
-
4.13 {9H, m, (meta on η -C H -C≡C-), (η -C H ), (-NHCH CO-)}, 3.66 (3H, s, -
5
4
5
5
2
OCH ), 1.36 (3H, d, J = 7.2 Hz, -CHCH );
3
3
1
3
C NMR (100 MHz) δ (CDCl ): 173.2 (C=O), 168.6 (C=O), 167.2 (C=O), 132.0
3
5
5
(
C ), 131.4 (C ), 127.8, 127.2, 91.7 (η -C H -C≡C-), 85.1 (η -C H -C≡C-), 70.7
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 69.2 (η -C H ), 68.2 (C
η -C H -C≡C-), 66.5 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 52.4 (-OCH ), 48.3 (-CHCH ), 43.5 (-NHCH CO-, -ve DEPT), 18.1 (-
5
4
3
3
2
CHCH ).
3
4
.3.6. N-{para-(ferrocenyl) ethynyl benzoyl} glycine L-alanine ethyl ester 9
Glycine L-alanine ethyl ester hydrochloride (0.52 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.30 g, 20%), m.p 115 - 117 C;
2
0
o
[
α]D = -23 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 509.1127
C H N O FeNa requires:
509.1140
2
6
26
2
4

ACCEPTED MANUSCRIPT
I.R. υmax (KBr): 3275 (NH), 2204 (-C≡C-), 1739 (C=Oester), 1652 (C=Oamide), 1604
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 389, 489 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.81 (2H, d, J = 8.0 Hz, ArH ), 7.54 - 7.51 {3H, m,
3
(ArH), (-CONH-)} 7.33 (1H, t, J = 7.2 Hz, -CONH-), 4.54 (1H, quin, J = 6.8 Hz, -
5
CHCH ), 4.53 (2H, t, J = 1.6 Hz, ortho on η -C H -C≡C-), 4.28 (2H, t, J = 1.6 Hz,
3
5
4
5
5
meta on η -C H -C≡C-), 4.26 (5H, s, η -C H ), 4.23 - 4.10 {4H, m, (-OCH CH ), (-
5
4
5
5
2
3
NHCH CO-)}, 1.44 (3H, d, J = 7.2 Hz, -CHCH ), 1.28 (3H, t, J = 7.2 Hz, -
2
3
OCH CH );
2
3
1
3
C NMR (100 MHz) δ (CDCl ): 172.8 (C=O), 168.9 (C=O), 165.2 (C=O), 132.0
3
5
5
(
C ), 130.4 (C ), 127.5, 126.9, 91.0 (η -C H -C≡C-), 84.9 (η -C H -C≡C-), 71.6
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.1 (η -C H ), 69.2 (C
η -C H -C≡C-), 66.0 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 61.6 (-OCH CH , -ve DEPT), 48.4 (-CHCH ), 42.0 (-NHCH CO-, -ve
5
4
2
3
3
2
DEPT), 18.7 (-CHCH ), 14.2 (-OCH CH ).
3
2
3
4
.3.7. N-{para-(ferrocenyl) ethynyl benzoyl} glycine D-alanine methyl ester 10
Glycine D-alanine methyl ester hydrochloride (0.48 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.21 g, 15%), m.p 129 - 131 C;
2
0
o
[
α]D = +25 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 495.0978
C H N O FeNa requires:
495.0983
2
5
24
2
4
I.R. υmax (KBr): 3354 (NH), 2207 (-C≡C-), 1735 (C=Oester), 1621 (C=Oamide), 1604
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 387, 492 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.73 (2H, d, J = 8.4 Hz, ArH ), 7.45 ( 2H, d, J = 8.4
3
Hz, ArH), 7.25 (1H, t, J = 5.6 Hz, -CONH-), 7.07 (1H, d, J = 6.8 Hz, -CONH-), 4.55
5
-
4.50 (1H, m, -CHCH ), 4.45 (2H, t, J = 1.6 Hz, ortho on η -C H -C≡C-), 4.21 -
3
5
4
5
5
4
.14 {9H, m, (meta on η -C H -C≡C-), (η -C H ), (-NHCH CO-)}, 3.68 (3H, s, -
5 4 5 5 2
OCH ), 1.38 ( 3H, d, J = 7.2 Hz, -CHCH );
3
3

ACCEPTED MANUSCRIPT
1
3
C NMR (100 MHz) δ (CDCl ): 173.2 (C=O), 168.6 (C=O), 167.2 (C=O), 132.0
3
5
5
(
C ), 131.4 (C ), 127.8, 127.2, 90.7 (η -C H -C≡C-), 84.2 (η -C H -C≡C-), 70.9
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 69.2 (η -C H ), 68.0 (C
η -C H -C≡C-), 65.9 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 52.0 (-OCH ), 47.9 (-CHCH ), 42.9 (-NHCH CO-, -ve DEPT), 18.9 (-
5
4
3
3
2
CHCH ).
3
4
.3.8. N-{para-(ferrocenyl) ethynyl benzoyl} glycine D-alanine ethyl ester 11
Glycine D-alanine ethyl ester hydrochloride (0.52 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.27 g, 18%), m.p 69 - 71 C;
2
0
o
[
α]D = +23 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 509.1154
C H N O FeNa requires:
509.1140
2
6
26
2
4
I.R. υmax (KBr): 3307 (NH), 2205 (-C≡C-), 1734 (C=Oester), 1651 (C=Oamide), 1604
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 387, 494 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.72 (2H, d, J = 8.0 Hz, ArH), 7.45 (2H, d, J = 8.0
3
Hz, ArH), 7.30 (1H, t, J = 7.2 Hz, -CONH-), 7.05 (1H, d, J = 6.8 Hz, -CONH-), 4.53
5
(
1H, quin, J = 6.8 Hz, -CHCH ), 4.42 (2H, t, J = 1.6 Hz, ortho on η -C H -C≡C-),
3
5
4
5
5
4
.20 - 4.18 {7H, m, (meta on η -C H -C≡C-), (η -C H )}, 4.15 - 4.10 {4H, m, (-
5 4 5 5
OCH CH ), (-NHCH CO-)}, 1.37 ( 3H, d, J = 7.2 Hz, -CHCH ), 1.20 (3H, t, J = 7.2
2
3
2
3
Hz, -OCH CH );
2
3
1
3
C NMR (100 MHz) δ (CDCl ): 172.7 (C=O), 168.2 (C=O), 167.9 (C=O), 132.1
3
5
5
(
C ), 130.4 (C ), 127.0, 126.5, 91.0 (η -C H -C≡C-), 84.7 (η -C H -C≡C-), 71.6
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.5 (η -C H ), 69.1 (C
η -C H -C≡C-), 66.7 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 61.6 (-OCH CH , -ve DEPT), 48.4 (-CHCH ), 42.0 (-ve DEPT), 18.2 (-
5
4
2
3
3
CHCH ), 14.1 (-OCH CH ).
3
2
3
4
.3.9. N-{para-(ferrocenyl) ethynyl benzoyl} glycine L-leucine ethyl ester 12
Glycine L-leucine ethyl ester hydrochloride (0.65 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1

ACCEPTED MANUSCRIPT
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.19 g, 12%), m.p 132 - 134 C;
2
0
o
[
α]D = -18 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 551.1617
C H N O FeNa requires:
551.1609
2
9
32
2
4
I.R. υmax (KBr): 3275 (NH), 2206 (-C≡C-), 1727 (C=Oester), 1640 (C=Oamide), 1605
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 396, 489 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.72 (2H, d, J = 8.4 Hz, ArH), 7.45 {2H, d, J = 8.4
3
Hz, ArH), 7.30 (1H, t, J = 5.2 Hz, -CONH-) 7.00 (1H, d, J = 8.0 Hz, -CONH-), 4.57 -
5
4
4
.51 {1H, m, -CHCH CH(CH ) )}, 4.45 (2H, t, J = 2.0 Hz, ortho on η -C H -C≡C-),
2
3 2
5
4
5
5
.20 - 4.15 { 9H, m, (meta on η -C H -C≡C-), (-NHCH CO-), (η -C H )}, 4.13 (2H,
5
4
2
5
5
q, J = 7.2 Hz, -OCH CH ), 1.57 - 1.45 {3H, m, -CHCH CH(CH ) )}, 1.18 (3H, t, J =
2
3
2
3 2
7
.2 Hz, -OCH CH ), 0.88 - 0.86 ( 6H, m, -CHCH CH(CH ) );
2 3 2 3 2
1
3
C NMR (100 MHz) δ (CDCl ): 171.8 (C=O), 168.9 (C=O), 167.1(C=O), 132.0 (C ),
3
q
5
5
5
1
31.7 (C ), 127.3, 126.8, 90.7 (η -C H -C≡C-), 84.1 (η -C H -C≡C-), 71.7 (C
η -
ortho
q
5
4
5
4
5
5
5
C H -C≡C-), 70.5 (η -C H ), 68.2 (C
η -C H -C≡C-), 66.1 (C η -C H -C≡C-),
5 4 ipso 5 4
5
4
5
5
meta
6
1.0 (-OCH CH , -ve DEPT), 50.1 (-CHCH CH(CH ) ), 42.9 (-NHCH CO-, -ve
2 3 2 3 2 2
DEPT), 41.3 (-CHCH CH(CH ) , -ve DEPT), 25.8 (-CHCH CH(CH ) ), 22.0 (-
2
3 2
2
3 2
CHCH CH(CH ) ), 21.9 (-CHCH CH(CH ) ), 14.0 (-OCH CH ).
2
3 2
2
3 2
2
3
4
.3.10. N-{para-(ferrocenyl) ethynyl benzoyl} glycine L-phenylalanine ethyl ester 13
Glycine L-phenylalanine ethyl ester hydrochloride (0.76 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.20 g, 12%), m.p 118 - 120 C;
2
0
o
[
α]D = -17 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 585.1442
C H N O FeNa requires:
585.1453
3
2
30
2
4
I.R. υmax (KBr): 3359 (NH), 2205 (-C≡C-), 1743 (C=Oester), 1631 (C=Oamide), 1605
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 390, 492 nm;

ACCEPTED MANUSCRIPT
1
H NMR (400 MHz) δ (CDCl ): 7.81 (2H, d, J = 8.0 Hz, ArH), 7.54 (2H, d, J = 8.0
3
Hz, ArH ), 7.25 - 7.19 {6H, m, (-CONH-), (-CHCH Ph)}, 6.87 (2H, d, J = 8.0 Hz, -
2
5
CONH-), 4.86 - 4.84 (1H, m, -CHCH Ph), 4.54 (2H, t, J = 1.6 Hz, ortho on η -C H -
2
5
4
5
5
C≡C-), 4.30 - 4.29 {7H, m, (meta on η -C H -C≡C-), (η -C H )}, 4.18 (2H, q, J = 7.2
5
4
5
5
Hz, -OCH CH ), 4.23 (2H, d, J = 4.8 Hz, -NHCH CO-), 3.20 - 3.08 ( 2H, m, -
2
3
2
CHCH Ph), 1.26 (3H, t, J = 7.2 Hz, -OCH CH );
2
2
3
1
3
C NMR (100 MHz) δ (CDCl ):171.2 (C=O), 168.1(C=O), 167.0 (C=O), 133.7 (C ),
3
q
5
5
1
32.0 (C ), 130.1, 129.3, 128.6, 127.8, 127.2, 126.1, 91.7 (η -C H -C≡C-), 84.9 (η -
q
5
4
5
5
5
C H -C≡C-), 71.1 (C
η -C H -C≡C-), 70.4 (η -C H ), 69.2 (C
η -C H -C≡C-),
meta 5 4
5
4
ortho
5
4
5
5
5
6
7.5 (Cipso η -C H -C≡C-), 62.7 (-OCH CH , -ve DEPT), 53.0 (-CHCH Ph), 42.6 (-
5 4 2 3 2
NHCH CO-, -ve DEPT), 38.0 (-CHCH Ph, -ve DEPT), 13.7 (-OCH CH ).
2
2
2
3
4
.3.11. N-{para-(ferrocenyl) ethynyl benzoyl} sarcosine glycine methyl ester 14
Sarcosine glycine methyl ester hydrochloride (0.49 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.23 g, 16%), m.p 124 - 126 C;
+
Mass spectrum: [M+Na] found: 495.1297
C H N O FeNa requires:
495.0983
2
5
24
2
4
I.R. υmax (KBr): 3286 (NH), 2206 (-C≡C-), 1746 (C=Oester), 1674 (C=Oamide), 1620
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 397, 486 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.45 - 7.35 {5H, m, (-CONH-), (ArH)}, 4.44 (2H, s,
3
5
5
5
ortho on η -C H -C≡C-), 4.30 - 3.85 {11H, m, (meta on η -C H -C≡C-), (η -C H ),
5
4
5
4
5
5
(
-N(CH )CH CO-), (-NHCH CO-)}, 3.70 (3H, s, -OCH ), 3.04 (3H, s, -
3 2 2 3
N(CH )CH CO-);
3
2
1
3
C NMR (100 MHz) δ (CDCl ): 172.1 (C=O), 168.9 (C=O), 167.2 (C=O), 131.7
3
5
5
(
C ), 130.0 (C ), 126.9, 125.7, 91.2 (η -C H -C≡C-), 84.1 (η -C H -C≡C-), 71.8
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 69.9 (η -C H ), 68.2 (C
η -C H -C≡C-), 65.9 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 51.7 (-OCH ), 46.2 (-N(CH )CH CO-, -ve DEPT), 41.2 (-NHCH CO-, -
5
4
3
3
2
2
ve DEPT), 38.1 (-N(CH )CH CO-).
3
2

ACCEPTED MANUSCRIPT
4
.3.12. N-{para-(ferrocenyl) ethynyl benzoyl} sarcosine glycine ethyl ester 15
Sarcosine glycine ethyl ester hydrochloride (0.53 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.23 g, 16%), m.p 79 - 81 C;
+
Mass spectrum: [M+Na] found: 509.1152
C H N O FeNa requires:
509.1140
2
6
26
2
4
I.R. υmax (KBr): 3284 (NH), 2205 (-C≡C-), 1744 (C=Oester), 1676 (C=Oamide), 1620
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 389, 495 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.65 - 7.35 {5H, m, (-CONH-), (ArH)}, 4.43 (2H, s,
3
5
5
5
ortho on η -C H -C≡C-), 4.30 - 3.85 {13H, m, (meta on η -C H -C≡C-), (η -C H ), (-
5
4
5
4
5
5
N(CH )CH CO-), (-NHCH CO-) (-OCH CH )}, 3.15 (3H, s, -N(CH )CH CO-), 1.17
3
2
2
2
3
3
2
(
3H, t, J = 7.2 Hz, -OCH CH );
2 3
1
3
C NMR (100 MHz) δ (CDCl ): 173.1 (C=O), 169.3 (C=O), 168.2 (C=O), 132.1
3
5
5
(
C ), 130.7 (C ), 127.1, 125.9, 90.9 (η -C H -C≡C-), 85.7 (η -C H -C≡C-), 72.0
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.1 (η -C H ), 69.1 (C
η -C H -C≡C-), 67.6 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 62.0 (-OCH CH , -ve DEPT), 49.6 (-N(CH )CH CO-, -ve DEPT), 42.3
5
4
2
3
3
2
(
-NHCH CO-, -ve DEPT), 38.5 (-N(CH )CH CO-), 14.3 (-OCH CH ).
2 3 2 2 3
4
.3.13. N-{para-(ferrocenyl) ethynyl benzoyl} sarcosine L-alanine ethyl ester 16
Sarcosine L-alanine ethyl ester hydrochloride (0.57 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.21 g, 14%), m.p 99 - 101 C;
2
0
o
[
α]D = -22 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 523.1292
C H N O FeNa requires:
523.1296
2
7
28
2
4
I.R. υmax (KBr): 3270 (NH), 2205 (-C≡C-), 1745 (C=Oester), 1675 (C=Oamide), 1614
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 389, 486 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.60 - 7.35 {5H, m, (-CONH-), (ArH)}, 4.51- 4.40
3

ACCEPTED MANUSCRIPT
5
5
{
3H, m, (ortho on η -C H -C≡C-), (-CHCH )}, 4.19 - 3.90 {11H, m, (meta on η -
5 4 3
5
C H -C≡C-), (η -C H ), (-N(CH )CH CO-), (-OCH CH )}, 3.01 (3H, s, -
5
4
5
5
3
2
2
3
N(CH )CH CO-), 1.36 (2H, d, J = 7.2 Hz, -CHCH ), 1.21 (3H, t, J = 7.2 Hz, -
3
2
3
OCH CH );
2
3
1
3
C NMR (100 MHz) δ (CDCl ): 172.7 (C=O), 169.0 (C=O), 168.2 (C=O), 133.8
3
5
5
(
C ), 132.0 (C ), 128.3, 127.4, 90.6 (η -C H -C≡C-), 85.0 (η -C H -C≡C-), 71.5
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.0 (η -C H ), 69.1 (C
η -C H -C≡C-), 64.6 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 61.6 (-OCH CH , -ve DEPT), 48.2 (-CHCH ), 40.1(-N(CH )CH CO-, -
5
4
2
3
3
3
2
ve DEPT), 38.3 (-N(CH )CH CO-), 18.3 (-CHCH ), 14.2 (-OCH CH ).
3
2
3
2
3
4
.3.14. N-{para-(ferrocenyl) ethynyl benzoyl} L-proline glycine ethyl ester 17
L-Proline glycine ethyl ester hydrochloride (0.61 g, 3.03 mmol) was used as a starting
material. The crude product was purified by column chromatography (eluent 1:1
hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
20
D
o
desired product as a red solid (0.27 g, 17%), m.p 58 - 60 C; [α] = 17 ;
+
Mass spectrum: [M+Na] found: 535.1282
C H N O FeNa requires:
535.1296
2
8
28
2
4
I.R. υmax (KBr): 3313 (NH), 2205 (-C≡C-), 1735 (C=Oester), 1652 (C=Oamide), 1604
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 395, 499 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.50 - 7.36 {5H, m, (-CONH-), (ArH)}, 4.74 (1 H, t,
3
5
J = 5.2 Hz, -N(CH CH CH )CHCO-), 4.45 (2H, s, ortho on η -C H -C≡C-), 4.19 -
2
2
2
5
4
5
5
4
.10 {9H, m, (meta on η -C H -C≡C-), (η -C H ), (-OCH CH )}, 3.95 (2H, d, J = 4.0
5
4
5
5
2
3
Hz, -NHCH CO-), 3.51 - 3.40 (2H, m, -N(CH CH CH )CHCO-), 2.40 - 1.70 ( 4H, m,
2
2
2
2
-
N(CH CH CH )CHCO-), 1.20 (3H, t, J = 7.2 Hz, -OCH CH );
2 2 2 2 3
1
3
C NMR (100 MHz) δ (CDCl ): 171.5 (C=O), 170.6 (C=O), 169.7 (C=O), 133.8
3
5
5
(
C ), 131.2 (C ), 127.4, 126.0, 90.7 (η -C H -C≡C-), 84.9 (η -C H -C≡C-), 71.9
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.4 (η -C H ), 68.1 (C
η -C H -C≡C-), 65.9 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 62.4 (-OCH CH , -ve DEPT), 59.8 (-N(CH CH CH )CHCO-), 50.4
5
4
2
3
2
2
2
(
-N(CH CH CH )CHCO, -ve DEPT), 41.5 (-NHCH CO-, -ve DEPT),
2 2 2 2
2
7.5 (-N(CH CH CH )CHCO-, -ve DEPT), 25.4 (-N(CH CH CH )CHCO-, -ve
2 2 2 2 2 2
DEPT), 13.7 (-OCH CH ).
2
3

ACCEPTED MANUSCRIPT
4
.3.15. N-{para-(ferrocenyl) ethynyl benzoyl} L-proline L-alanine ethyl ester 18
L-Proline L-alanine ethyl ester hydrochloride (0.65 g, 3.03 mmol) was used as a
starting material. The crude product was purified by column chromatography (eluent
1
:1 hexane: ethyl acetate) and recrystallisation from hexane: ethyl acetate yielded the
o
desired product as a red solid (0.21 g, 13%), m.p 52 - 54 C;
2
0
o
[
α]D = -69 (c 0.1, EtOH);
+
Mass spectrum: [M+Na] found: 549.1467
C H N O FeNa requires:
549.1453
2
9
30
2
4
I.R. υmax (KBr): 3285 (NH), 2202 (-C≡C-), 1736 (C=Oester), 1672 (C=Oamide), 1608
-1
(
C=Oamide) cm ;
UV-Vis λmax EtOH: 392, 493 nm;
1
H NMR (400 MHz) δ (CDCl ): 7.69 - 7.48 {5H, m, (ArH), (-CONH-)}, 4.68 (1H, t, J
3
5
=
6.4 Hz, -N(CH CH CH )CHCO-), 4.57 (2H, s, ortho on η -C H -C≡C-), 4.46 (1H,
2
2
2
5
4
5
quin, J = 6.8 Hz, -CHCH ), 4.28 (2H, s, meta on η -C H -C≡C-), 4.16 - 4.12 {7H, m,
3
5
4
5
(
η -C H ), (-OCH CH )}, 3.60 - 3.40 (2H, m, (-N(CH CH CH )CHCO-), 2.40 - 1.56
5 5 2 3 2 2 2
(
4H, m, (-N(CH CH CH )CHCO-)}, 1.36 (3H, d, J = 6.4 Hz, -CHCH ), 1.21 (3H, t, J
2 2 2 3
=
6.8 Hz, -OCH CH );
2 3
1
3
C NMR (100 MHz) δ (CDCl ): 173.8 (C=O), 171.9 (C=O), 169.1 (C=O), 133.0
3
5
5
(
C ), 131.2 (C ), 128.9, 127.9, 90.7 (η -C H -C≡C-), 84.4 (η -C H -C≡C-), 72.0
q q 5 4 5 4
5
5
5
5
(
Cortho η -C H -C≡C-), 70.2 (η -C H ), 68.7 (C
η -C H -C≡C-), 67.3 (C
η -
ipso
5
4
5
5
meta
5
4
C H -C≡C-), 62.4 (OCH CH , -ve DEPT), 60.1 (-N(CH CH CH )CHCO-), 50.6 (-
5
4
2
3
2
2
2
N(CH CH CH )CHCO-, -ve DEPT), 48.4 (-CHCH ), 27.8 (-N(CH CH CH )CHCO-,
2
2
2
3
2
2
2
-
ve DEPT), 25.6 (-N(CH CH CH )CHCO-, -ve DEPT), 18.9 (-CHCH ), 13.9 (-
2 2 2 3
OCH CH ).
2
3
4
.4. General procedure for in vitro cytotoxicity assays
4
.4.1. Biological Assays. Cell Line.
H1299 was obtained from the American Tissue Culture Centre (ATCC). The cell line
o
was grown in RPMI-1640 supplemented with 10% fetal calf serum (FCS) at 37 C in
a 5% CO humidified chamber.
2
4
.4.2. In Vitro Proliferation Assays.
Cells in the exponential phase of growth were harvested by trypsinisation and a cell
4
suspension of 1 x 10 cells per ml was prepared in fresh culture medium. The cell

ACCEPTED MANUSCRIPT
suspension (100 µL) was added to a flat bottom 96-well plate (Costar, 3599), plates
were agitated gently in order to ensure even dispersion of cells over the surface of the
o
wells, and then cells were incubated for an initial 24 hours in a 37 C, 5% CO
2
incubator, to allow cell attachment to the wells. A 10 mM stock solution of a test
sample was prepared in dimethyl sulfoxide; dilute solutions of the test sample were
prepared at 2X final concentration by spiking the cell culture medium with a
calculated amount of the stock solution. 100 µL aliquots of each dilute solution was
added to each well of the plate, the plate was gently agitated, and then incubated at 37
o
C, 5% CO for 5-6 days, until cell confluency reached 80-90%. Assessment of cell
2
survival in the presence of the compounds 4-18 was determined by the acid
phosphatase assay [32]. The acid phosphatase assay is highly sensitive and is easier to
perform than the neutral red assay as it involves fewer steps and fewer reagents. It is
also more convenient than the MTT assay because of the inherent problem of removal
of the medium from the insoluble crystals. The reproducibility between replicate wells
is excellent in the acid phosphatase assay and in many cases it has been shown to be
better than the neutral red assay and the MTT assay.
The percentage cell growth in the presence of each compound was determined relative
to the control cells. The concentration of compounds causing a 50% growth inhibition
(
IC of the compound) was determined using Calcusyn (Biosoft, UK).
50
Acknowledgements
This research was partly supported by the Health Research Board, Grant Reference
Number HRA/09/86.
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[
[
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[
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ACCEPTED MANUSCRIPT
Scheme 1. Synthesis of N-{para-(ferrocenyl) ethynyl benzoyl} amino acid and
dipeptide ethyl esters, (i) TEA, PPh , Bis(triphenylphosphine)palladium(II) dichloride,
3
THF, Cu(I), (ii) EDC, HOBt, triethylamine, amino acid and dipeptide esters, R=
GABA(OMe) 4, GABA(OEt) 5, GlyGly(OMe) 6, GlyGly(OEt) 7, Gly-L-Ala(OMe) 8,
Gly-L-Ala(OEt) 9, Gly-D-Ala(OMe) 10, Gly-D-Ala(OEt) 11, Gly-L-Leu(OEt) 12, Gly-
L-Phe(OEt) 13, SarGly(OMe) 14, SarGly(OEt) 15, Sar-L-Ala(OEt) 16, L-ProGly(OEt)
17 and L-Pro-L-Ala(OEt) 18.

ACCEPTED MANUSCRIPT
Figure 1. MS/MS spectrum of N-{para-(ferrocenyl) ethynyl benzoyl) glycine glycine
ethyl ester 7.
Figure 2. Percentage growth inhibition at 10 µM on H1299 lung cancer cells for N-
{
para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide esters 4-18.

ACCEPTED MANUSCRIPT
Ferrocenyl bioconjugate
R
Compound no.
% growth inhibition
at 10 µM
GABA(OMe)
GABA(OEt)
Gly Gly(OMe)
Gly Gly(OEt)
4
5
6
7
8
55 ± 3.35
85 ± 1.07
34 ± 2.49
70 ± 2.84
22 ± 5.47
95 ± 1.62
23 ± 4.89
72 ± 2.01
53 ± 3.17
28 ± 1.74
47 ± 4.03
25 ± 4.10
82 ± 4.75
62 ± 5.06
87 ± 1.12
Gly L-Ala(OMe)
Gly L-Ala(OEt)
Gly D-Ala(OMe)
Gly D-Ala(OEt)
Gly L-Leu(OEt)
Gly L-Phe(OEt)
Sar Gly(OEt)
Sar Gly(OMe)
Sar L-Ala(OEt)
L-Pro Gly(OEt)
L-Pro L-Ala(OEt)
9
10
11
12
13
14
15
16
17
18
Table 1. Percentage growth inhibition at 10 µM on H1299 lung cancer cells for N-
para-(ferrocenyl) ethynyl benzoyl} amino acid and dipeptide esters 4-18.
{

ACCEPTED MANUSCRIPT
Compound Name
No.
19
IC50
Cisplatin
1.5 ± 0.10
Carboplatin
20
5
10 ± 1.60
4.9 ± 4.12
6.9 ± 2.14
3.8 ± 1.92
6.1 ± 3.41
7.1 ± 2.46
8.3 ± 3.10
5.7 ± 2.91
N-{para-(ferrocenyl) ethynyl benzoyl} GABA(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} Gly Gly(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} Gly L-Ala(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} Gly D-Ala(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} Sar L-Ala(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} L-Pro Gly(OEt)
N-{para-(ferrocenyl) ethynyl benzoyl} L-Pro L-Ala(OEt)
7
9
11
16
17
18
Table 2. IC values for compounds 5, 7, 9, 11, 16, 17 and 18, cisplatin 19 and
5
0
carboplatin 20 against human lung carcinoma cell line H1299.