Synthesis and antiproliferative activity of (Z+E)-1-[4-(2- (cyclopentadienyltricarbonylmanganese)-2-oxo-ethoxy)phenyl]-1, 2-di(p-hydroxyphenyl)-but-1-ene against breast cancer cells

Article abstract of DOI:10.1002/aoc.2934

This paper describes the synthesis of (Z + E)-1-[4-(2- (cyclopentadienyltricarbonylmanganese)-2-oxo-ethoxy)phenyl]-1, 2-di(p-hydroxyphenyl)-but-1-ene. Two synthetic pathways were explored. The best pathway consisted of the alkylation of 1,2-bis-[4-(tert-b

Full text of DOI:10.1002/aoc.2934

Full Paper
Received: 21 June 2012
Revised: 6 August 2012
Accepted: 11 September 2012
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/aoc.2934
Synthesis and antiproliferative activity of (Z+E)-1-
[4-(2-(cyclopentadienyltricarbonylmanganese)
-2-oxo-ethoxy)phenyl]-1,2-di(p-hydroxyphenyl)-
but-1-ene against breast cancer cells†
Tesnim Dallagia,b,c, Mouldi Saidic, Gérard Jaouena,b and Siden Topa,b*
This paper describes the synthesis of (Z + E)-1-[4-(2-(cyclopentadienyltricarbonylmanganese)-2-oxo-ethoxy)phenyl]-1,2-di(p-
hydroxyphenyl)-but-1-ene. Two synthetic pathways were explored. The best pathway consisted of the alkylation of 1,2-bis-[4-
(tert-butyl-dimethylsilyloxy)phenyl]-1-(4-hydroxyphenyl)but-1-ene with BrCH2COOEt. The ester obtained was transformed into
the Weinreb amide by reaction with HN(OMe)Me–HCl. The reaction of lithium manganese tricarbonylcyclopentadienide with
the Weinreb amide produced 1-[4-(2-(cyclopentadienyltricarbonylmanganese)-2-oxo-ethoxy)phenyl]-1,2-di(p-tert-butyldimethyl-
siloxyphenyl)-but-1-ene. The deprotection of phenolic functions of the latter compound led to the formation of the final
compound. The Z and E isomers could be separated but the isomerization of these isomers from one to another is an easy process.
The Z + E compound 2 was tested against the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer
cell lines. The IC50 values of compound 2 were 4.80ꢀ 2.00mM and 4.79ꢀ 0.70mM for MCF-7 cells and MDA-MB-231 cells, respec-
tively, which was three times better than the ferrocenyl analogue. Copyright © 2012 John Wiley & Sons, Ltd.
Keywords: manganese; cymantrene; tamoxifen; breast cancer
Pursuing research in this field, we thought it would be interesting
to study the cymantrenyl compound 2, an analogue of 1, for the
Introduction
Bioorganometallic chemistry, which is meant to use organometallic
complexes in real problems of biological interest, is a discipline that
lies at the interface between organometallic chemistry and biology.
This area has been extensively developed in the last two
decades.[1–7] Recently, an important field of application in this topic
was described under the term ’medicinal organometallic chemis-
try’.[8] One of the most prominent examples of the use of organome-
tallic compounds is hydroxyferrocifen (FcOHTAM), a ferrocenyl
analogue of tamoxifen (Fig. 1).[9–12]
Tamoxifen is a drug which is extensively used for the treatment
of breast cancer.[13–16] It acts as an anti-oestrogen and is only active
against hormone-dependent cancer cell lines. Tamoxifen is com-
pletely inactive against hormone-independent cancer cell lines.
The use of tamoxifen for a long period leads to the development
of drug resistance phenomena. In order to find alternative drugs
with wider spectra of applications, the organometallic approach
has emerged as one of the most innovative strategies. Hydroxyfer-
rocifen was shown to be very active against both hormone-
dependent MCF-7 and hormone-independent MDA-MB-231 breast
cancer cell lines.[12] This activity was further improved by replacing
the ferrocenyl group with a ferrocenophane motif.[17,18]
following reasons: firstly, 2 may exhibit antiproliferative effects that
differ from those of 1; secondly, compound 2 may be used as a pre-
cursor for other cyclopentadienyl metal complexes (for example,
via a reaction of decomplexation–recomplexation, it may be possi-
ble to transform manganese compounds into rhenium or titanium
complexes);[21,22] and thirdly, 2 may be used as a model for the
technetium analogue. Technetium compounds play an important
role as imaging agents.[23–25] For this purpose, we now describe
the synthesis of 2 and its antiproliferative effects on hormone-
dependent MCF-7 and hormone-independent MDA-MB-231 breast
cancer cell lines.
*
Correspondence to: Siden Top, Chimie ParisTech (Ecole Nationale Supérieure de
Chimie de Paris), Laboratoire Charles Friedel, UMR CNRS 7223, 11 rue P. et M.
Curie, 75231 Paris CEDEX 05, France. E-mail: siden-top@chimie-paristech.fr
† This paper is dedicated to Professor Stefan Toma on the occasion of his 75th
In order to preserve the triaryl butene core of tamoxifen, the
ferrocenyl compound 1 was prepared (Fig. 2).[19,20] With an IC50
value of 11.3 mMfor MCF-7 hormone-dependent breast cancer
cells, 1 is less active than FcOHTAM and 1,1-bis-(p-hydroxyphenyl)-
2-ferrocenyl-but-1-ene (IC50 = 0.64ꢀ 03 mM).[11,12] However, 1 still
exhibits good affinity for oestrogen receptor alpha (relative
binding affinity = 14%).
birthday.
a ENSCP Chimie ParisTech, Laboratoire Charles Friedel (LCF), 75005 Paris, France
b CNRS, UMR 7223, 75005 Paris, France
c
Laboratoire des Radiopharmaceutiques, Centre National des Sciences et
Technologies Nucléaires, Technopôle de Sidi Thabet, 2020 Sidi Thabet, Tunisia
Appl. Organometal. Chem. 2013, 27, 28–35
Copyright © 2012 John Wiley & Sons, Ltd.

Antiproliferative activity of cymantrenyl compound against breast cancer
OH
OH
Fe
O(CH2)3NMe2
O(CH2)2NMe2
O(CH2)2NMe2
(Z)-Tamoxifen
(Z)-TAM
(Z)-Hydroxytamoxifen
(Z)-OHTAM
(Z+E)-Hydroxyferrocifen
(Z+E)-FcOHTAM
Figure 1. Molecules of tamoxifen, hydroxytamoxifen and hydroxyferrocifen.
OH
OH
O
O
HO
O
HO
O
Fe
Mn(CO)3
2
1
Figure 2. Ferrocenyl and cymantrenyl derivatives of triaryl butane.
in THF at ꢁ70 ꢂC for 1 h resulted in only a moderate yield of
compound 4 (25.8%). Along with compound 4, 36% yield
of manganese tricarbonylcyclopentadiene was recovered after
the reaction.
Following the alkylation procedure of triarylbutene 5 by chloroa-
cetylferrocene,[20] compound 5 was alkylated with bromide 4 in ac-
etone using caesium carbonate (Cs2CO3) as a base. Compound 6
was obtained as a mixture of Z and E isomers in 9% yield. This
low yield is due to an incomplete reaction and also to the sensitivity
of the t-butyldimethylsilyl protecting group to a basic medium
leading to the formation of a mixture of several compounds. The
use of other bases, such as K2CO3 or NaOH, did not improve the
reaction yield.
Results and Discussion
Synthesis
Two different pathways were used for the synthesis of compound 2.
The first synthetic route consisted of the preparation of
bromoacetyl-cyclopentadienyltricarbonylmanganese followed by
Williamson alkylation of a phenolic derivative of triarylbutene with
this halide. Schemes 1 and 2 show the synthetic pathway adopted.
In the first step, the Weinreb amide 3 was prepared by reacting
the bromoacetyl bromide with N,O-dimethylhydroxylammonium
according to the procedures outlined in the literature.[26] Com-
pound 3 was obtained in high yield (81.2%). The reaction of com-
pound 3 with lithium manganese tricarbonylcyclopentadienide
HN(OMe)Me,HCl
CHCl3, pyridine
+
BrCH2COBr
Li
Mn(CO)3
O
OMe
Br
N
Br
Me
THF, -70°C
O
Mn(CO)3
25.8%
3
81.2%
4
Scheme 1. Synthesis of bromoacetyl-cyclopentadienyltricarbonylmanganese.
Appl. Organometal. Chem. 2013, 27, 28–35
Copyright © 2012 John Wiley & Sons, Ltd.
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T. Dallagi et al.
OTBDMS
O
Br
TBDMS = tBuMe2Si
Mn(CO)3
4
TBDMSO
OH
(Z+E)-5
Cs2CO3
Acetone
OTBDMS
OH
HClconc
EtOH
O
O
O
TBDMSO
HO
O
Fe
(Z+E)-2
Mn(CO)3
(Z+E)-6 9%
Scheme 2. Synthesis of compound (Z + E)-2.
In order to improve the access of 6, a second synthetic
approach was explored (Scheme 3). This new reaction pathway
differed from the first synthetic approach by first performing
the alkylation of compound 5 with ethyl bromoacetate.
hormone-independent MDA-MB-231 breast cancer cells. Table 1
shows the effects at 1 and 10 mM, as well as the IC50 values.
At 10 mM, compound 2 was found to be very active against both
cancer cell lines. The IC50 values of 4.80ꢀ 2.00 mM and 4.79ꢀ 0.70
mM were measured for MCF-7 cells and MDA-MB-231 cells, respec-
tively. Thus compound 2 shows almost the same antiproliferative
effects for hormone-dependent and hormone-independent breast
cancer cell lines. This result is interesting, as it has been shown
before that cymantrene and cyrhetrene compounds are not very
active against these cancer cells. Thus 1,10-bis(4-hydroxyphenyl)-
2-(tricarbonylmanganese cyclopentadienyl)-but-1-ene and 1,10-bis
(4-hydroxyphenyl)-2-(tricarbonylrhenium cyclopentadienyl)-but-1-
ene did not show an antiproliferative effect on MDA-MB-231 cells
at 1 mM, and they even exhibited a slightly proliferative effect on
MCF-7 cells.[27] In addition, the attachment of the cymantrenyl
group to so-called cell-penetrating peptides has been shown to
enhance their cytotoxic activity against MCF-7 cells. However, the
IC50 values of these compounds were in the range of 15–60 mM
and thus higher than that of 2.[28,29] We show here that, by selecting
a judicious structure, cymantrenyl compounds can also have
decent antiproliferative effects, as 2 performed even better than
its ferrocenyl analogue, compound 1 (IC50 = 11.3 mM).[19]
The reaction of ethyl bromoacetate with 5 in the presence of
Cs2CO3 provided ester 7 as a mixture of two isomers (Z and E) that
could be separated by silica gel column chromatography using
ethyl ether–petroleum ether (1:20) as the eluent. E-7 and Z-7 were
obtained in yields of 22.4% and 27%, respectively. The overall yield
of the reaction was 49.4%. The structure of Z-7 was identified by
correlation spectroscopy (COSY), heteronuclear multiple bond
correlation (HMBC), heteronuclear multiple quantum coherence
(HMQC) and nuclear Overhauser effect spectroscopy (NOESY)
NMR. This identification allowed the structural attribution of
all isomers in this study. The reaction of each isomer of 7 with N,
O-dimethylhydroxylamine chloride in the presence of AlMe3 in
dichloromethane at ꢁ15 ꢂC gave amides Z-8 and E-8 in very good
yields (72% and 71%, respectively).
The reaction of lithium manganese tricarbonylcyclopentadienide
with Z-8 at ꢁ70 ꢂC furnished a Z-6 yield of 22% (Scheme 4).
The deprotection of phenolic groups was easily achieved by heating
the Z-6 solution in ethanol in the presence of HCl at 80 ꢂC. E-2 was first
obtained at a yield of 48%. The E configuration was attributed to this
isomer because it was prepared from Z-7. We observed that Z-7 was
not stable in solution with respect to the isomerization reaction. In
acetone solution at room temperature, Z-7 progressively transformed
to E-7 and, after 4 days, the proportion of Z:E isomers was 42:58 (deter-
mined by NMR). Therefore, in biological media, 7 should be considered
a mixture of the Z/E isomers even when using a pure isomer.
Conclusion
In this study, (Z+ E)-1-[4-(2-(cyclopentadienyltricarbonylmanganese)-
2-oxo-ethoxy)phenyl]-1,2-di(p-hydroxyphenyl)-but-1-ene, compound
2, was prepared. Compound 2 is characterized by the presence of a
triaryl butene core, like tamoxifen. It is possible to separate the Z
isomer from the E isomer, but the isomerization of these compounds
is an easy process. The compounds were found to have antiprolifera-
tive effect against the hormone-dependent MCF-7 and hormone-
independent MDA-MB-231 breast cancer cell lines. We have shown
Antiproliferative Effects
The effect of compound 2 on the proliferation of cancer cells was
tested on hormone-dependent MCF-7 breast cancer cells and
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Appl. Organometal. Chem. 2013, 27, 28–35

Antiproliferative activity of cymantrenyl compound against breast cancer
O-TBDMS
O
Br
OEt
TBDMS-O
OH
(Z+E)-5
Cs2CO3
Acetone
O
OEt
O-TBDMS
O
O
OEt
TBDMS-O
O
TBDMS-O
O-TBDMS
27%
Z-7
E-7
22.4%
HN(OMe)Me,HCl
HN(OMe)Me,HCl
AlMe3, CH2Cl2, -15°C
AlMe3, CH2Cl2, -15°C
O
N(OMe)Me
O-TBDMS
O
O
N(OMe)Me
TBDMS-O
O
TBDMS-O
O-TBDMS
E-8 71%
Z-8
72%
Scheme 3. Synthesis of compounds Z and E-8.
that the good cytotoxic activity of hydroxyferrocifen is due to the
presence of the ferrocenyl double-bond phenol motif, which allows
for the formation of quinone methide, its active metabolite. The
low cytotoxic activity of 2 compared to that of hydroxyferrocifen
may be a consequence of the absence of this motif. Interestingly, 2
is more active than the ferrocenyl analogue, in which there is no
conjugation between the organometallic unit and the phenol.
Bruker spectrometer. Mass spectrometry was performed with a
Nermag R 10-10C spectrometer. Elemental analyses were performed
by the microanalysis services of ICSN (Gif sur Yvette, France). High-
resolution mass spectra were acquired with an electrospray time-
of-flight (ESI-TOF, LCT Premier XE, Waters) mass spectrometer in
the positive or negative ion mode. Melting points were measured
with a Kofler device. Determination of the cytotoxicity of the
complexes was performed at IMAGIF (ICSN, Gif sur Yvette, France).
Experimental
N-Methoxy-N-methyl-bromoacetamide (3)
All air-sensitive reactions were carried out under argon atmosphere,
using standard Schlenk and vacuum-line techniques. Anhydrous THF
was obtained by distillation from sodium–benzophenone. Thin-layer
chromatography (TLC) was performed on silica gel 60 GF254. Flash
chromatography was performed on silica gel Merck 60 (40–60 mm).
Infrared spectra were recorded on an IR-FT BOMEM Michelson-100
spectrometer equipped with a deuterated triglycine sulfate (DTGS)
detector. 1 H and 13C NMR spectra were recorded on a 300 MHz
Grounded N,O-dimethylhydroxylamine hydrochloride (2.14 g,
22mmol) was partially dissolved in ethanol-free chloroform
(25 ml) under argon. Pyridine (3.48 g, 44mmol) was added and
the mixture was stirred for 20 min. In another Schlenk tube,
bromoacetylbromide (4.8 g, 22mmol) was dissolved in chloroform
(15 ml) and cooled to 5 ꢂC (ice bath). The first solution was added
to the second solution (5min). The mixture was stirred for 1 h.
Appl. Organometal. Chem. 2013, 27, 28–35
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T. Dallagi et al.
O
O
N(OMe)Me
O
O
Li
Mn(CO)3
Mn(CO)3
THF, -70°C
TBDMS-O
O-TBDMS
22%
TBDMS-O
O-TBDMS
Z-6
Z-8
HCl,
Ethanol
O
O
Mn(CO)3
Acetone
(isomerisation)
Z-2
E-2
42/58 ratio
HO
OH
48%
E-2
Scheme 4. Synthesis of compound E-2.
and the solvent evaporated under reduced pressure. The crude
product was purified by silica gel column using diethyl ether–
pentane (1:1) as the eluent. Unreacted CpMn(CO)3 was first eluted
(74 mg, 36%). The second fraction was identified as compound 4
(yellow solid, 84 mg, 25.8% yield). Rf = 0.75 (diethyl ether–pentane,
1:1). 1 H NMR (300 MHz, CD3COCD3): d 4.27 (s, 2Η, CΗ2), 5.08 (t,
2 H, J = 1.8Hz, C5H4), 5.68 (t, 2 H, J= 1.8 Hz, C5H4) 13C NMR
(75 MHz, CD3COCD3): d 32.1 (CH2), 85.9, 88.6 (CH, C6H4), 89.8 (Cip,
C5H4), 190.2 (CO). M.p. 76 ꢂC. MS (ESI): m/z = 383.3 [MCH3COO]-. IR
(CH2Cl2, cmꢁ1): 2033 and 1952 n (Mn(CO)), 1681 n(CO). Elemental
analysis calcd for C10H6BrMnO4: C, 36.96; H, 1.86. Found: C, 37.76;
H, 1.84.
Table 1. Cell growth inhibition (%) by 2 for MCF-7 and MDA-MB-231
breast cancer cell lines at 1 and 10 mM, as well as IC50 values
Cancer cell
lines tested
% inhibition
IC50 (mM)
at 1 mM
at 10 mM
MCF-7
17 ꢀ 3
6 ꢀ 5
83 ꢀ 03
89 ꢀ 2
4.80 ꢀ 2.00
4.79 ꢀ 0.70
MDA-MB-231
Dichloromethane (100 ml) was added and the mixture was
poured into water (100 ml). The products were extracted with
dichloromethane (2ꢃ 100ml). The organic layer was dried over
MgSO4 and evaporated under reduced pressure. N-Methoxy-N-
methyl-bromoacetamide (3) was obtained as an oil (3.45 g, 86 %
yield), Rf = 0.36 (diethyl ether–pentane 1:1). 1 H NMR (300 MHz,
CDCl3): d 3.22 (s, 3 H, Me); 3.78 (s, 3 H, MeO), 4.00 (s, 2 H, CH2) 13C
NMR (75.5MHz, CDCl3): d 25.1 (Me); 32.6 (CH2), 61.6 (OMe), 167.5
(CO). IR (CH2Cl2, cmꢁ1) : 1669.8 (CO). MS (CI): m/z = 199 [M + NH4]+,
182 [M + H]+.
(Z)- and (E)-1-[4-(2-(Cyclopentadienyltricarbonylmanganese)-
2-oxo-ethoxy-phenyl]-1,2-di(p-tert-butyldimethylsiloxyphenyl)
but-1-ene (6)
Cs2CO3 (326 mg, 1 mmol) was added to a solution of compound 5
(560.9 mg, 1 mmol) in 15 ml acetone. A solution of 4 (277 mg,
0.85 mmol) in acetone (7 ml) was added dropwise (15 min). The
mixture was stirred for 1 h and then filtered over silica gel and
evaporated under reduced pressure. TLC of the crude products
showed the presence of both starting materials and other com-
pounds. Some of these compounds may come from 5 by the loss
of t-butyldimethylsilyl protecting group. A first purification by
silica gel column, using diethyl ether–pentane (1:5) as the eluent,
allowed the isolation of one fraction (140 mg) which mainly
contains 6. After a second purification by column, using the same
eluent, 73 mg pure (Z + E)-6 was isolated (9% yield). The
compound was crystallized from pentane, giving pale-yellow
crystals containing almost only one isomer. Rf (diethyl ether–
pentane, 1:5) = 0.39. 1 H NMR (300 MHz, CD3COCD3): d 0.12 (s,
2-Bromoacetyl-cyclopentadienyltricarbonylmanganese (4)
CpMn(CO)3 (206 mg, 1 mmol) was dissolved in 3 ml THF under
argon. The solution was cooled to ꢁ70 ꢂC, then nBuLi (0.48ml,
1.2mmol, 2.5 M in hexane) was added. The mixture was stirred at
ꢁ70 ꢂC for 1 h 30 min. Then, a solution of 3 (273 mg, 1.5ml) in
2 ml THF was added. The mixture was stirred again for 1 h at
ꢁ70 ꢂC. 2 ml of 1/10 HCl solution was added and the cold bath
was removed. After 5 min, 20 ml of 1/10 HCl solution was added
and the product was extracted with 3ꢃ 30 ml diethyl ether. The
organic layer was washed with 20ml water, dried over MgSO4,
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Appl. Organometal. Chem. 2013, 27, 28–35

Antiproliferative activity of cymantrenyl compound against breast cancer
6 H, (CH3)2Si), 0.17 (s, 6 H, (CH3)2Si), 0.91 (t, 3 H, J = 6.0 Hz, CH3),
0.93 (s, 9 H, t-Bu), 0.97 (s, 9 H, t-Bu), 2.44 (q, 2 H, J = 6.0 Hz, CH2),
5.11 (s, 2 H, OCH2), 5.21 (t, 2 H, J = 2.2 Hz, C5H4), 5.88 (t, 2 H,
J = 2.2 Hz, C5H4), 6.52 (d, 2 H, J = 6.5 Hz, C6H4), 6.66 (d, 2 H,
J = 6.5 Hz, C6H4), 6.73 (d, 2 H, J = 6.5 Hz, C6H4), 6.9 (d,
4 H, J = 6.5 Hz, C6H4), 7.16 (d, 2 H, J = 6.5 Hz, C6H4). 13C NMR
(75 MHz, CDCl3): d ꢁ4.4 (Si (CH3)2), 13.6 (CH3 of C2H5), 18.2 (Cq
of t-Bu), 25.7 (CH3 of t-Bu), 28.7 (CH2 of Et), 71.9 (CH2 of CH2CO)),
83.7 (C5H4), 87.5 (C5H4), 114.1, 118.8, 119.4, 130.6, 130.8 and131.8
(CHar), 135.3–153.4 (C═C and Car), 191.3 (CO). IR (CH2Cl2, cmꢁ1):
2033 and 1952 (Mn(CO)), 1681 (CO). M.p.118 ꢂC. MS (ESI): m/
z = 822.6 [MNH4]+. Elemental analysis calcd for C44H53MnO7Si2:
C, 65.65; H, 6.64. Found: C, 64.88; H, 6.76.
25.7 and 25.8 (CH3 of t-Bu), 28.8 (C3), 61.4 (C25), 65.8 (C23), 114.3
(C7 + C9), 118.9 (C13 + C15), 119.5 (C19 + C21), 130.7 (C18 + C22),
130.8 (C6 + C10), 132.0 (C12 + C16), 135.5 (C17), 136.5 (C11), 137.3
(C1), 137.6 (C5), 140.9 (C2), 153.5 (CC14), 153.8 (C20), 156.5 (C8),
169.1 (C24). IR (CH2Cl2, n cmꢁ1) :1755.7 (CO), 1603.5 (C═C). MS (EI)
+
•
646 [M] ). Anal: calcd for C38H54O5Si2 C,70.54; H,8.41. Found:
C,70.72; H, 8.81. The Z configuration of this isomer was identified
by COSY, HMBC, HMQC and NOESY NMR. The NOESY spectrum
showed correlation between protons H3, and also protons H4, with
the aromatic protons H6,10 and H18,22.
Compound Z-8
The reaction was carried out at ꢁ10 ꢂC under argon. Compound Z-7
(647mg, 1 mmol) was dissolved in distilled dichloromethane (6ml)
and the solution was cooled to ꢁ10 ꢂC. HNMe(OMe)–HCl (195 mg,
2 mmol) was added. Then, AlMe3 (0.8ml, 2 mmol, 2.5M in toluene)
was added dropwise (10 min). The stirring was maintained for
30min. The mixture was diluted with dichloromethane (50 ml),
washed with water (2ꢃ 30 ml), dried over MgSO4 and filtered. After
concentration under reduced pressure, the crude product was
chromatographed on silica gel column with diethyl ether–pentane
(2:1) solution as the eluent to yield compound Z-8 as a yellow solid
(474mg; 72% yield; m.p. 97 ꢂC). Rf = 0.65, diethyl ether–pentane,
2:1). 1 H NMR (300MHz, CDCl3): 0.10 (s, 6 H, (CH3)2Si), 0.15 (s, 6 H,
(CH3)2Si), 0.89 (s, 9 H, CH3 of t-Bu), 0.91 (t, 3 H, CH3 of Et), 0.96
(s, 9 H, CH3 of t-Bu), 2.44 (q, 2 H, CH2 of Et), 3.25 (s, 3 H, CH3 of
N-CH3), 3.77 (s, 3 H, OCH3), 4.63 (s, 2 H, CH2 of OCH2), 6.46 (d,
2 H, J = 8.7Hz, C6H4), 6.61 (d, 2 H, J = 8.6Hz, C6H4), 6.67 (d, 2 H,
J = 8.7 Hz, C6H4), 6.90 (d, 2 H, J = 8.6 Hz, C6H4), 6.92 (d, 2 H,
J = 8.6 Hz, C6H4), 7.13 (d, 2 H, J = 8.6 Hz, C6H4). 13C NMR (75.5MHz,
CDCl3): d ꢁ4.4 (Si(CH3)2), 13.6 (CH3 of Et), 18.1 and 18.2 (Cq of t-
Bu), 25.6 (CH3 of t-Bu), 28.7 (CH2 of Et), 29.2 (CH3 of NCH3), 61.6
(OCH2), 65.7 (NOCH3), 114.5, 118.8, 119.4, 130.6 and 131.9 (CHarom),
135.5, 137.3, 140.7, 153.4, 153.7 and 156.9 (C═C and Carom), 170
(C═O). IR (CH2Cl2, cmꢁ1): 1692.4 (CO), 1603.7 (C═C). MS (EI): m/z:
Compound (Z + E)-7
The reaction was carried out at room temperature. Compound 5
(5.5 g, 9.8mmol) was dissolved in dry acetone (120 ml) and Cs2CO3
(4.5 g, 13.8 mmol) was added in one portion. Then, BrCH2CO2Et
(2.3 g, 13.8 mmol) was added dropwise to the solution. The reaction
mixture was stirred for 1 h, filtered and the solvent was removed
under reduced pressure. The crude product was chromatographed
on a silica gel column with diethyl ether–petroleum ether (1:20)
solution as the eluent. First fraction: E-7 (1.34 g, colourless oil, 22%
yield ). Rf = 0.52, ether–pentane, 1:10). 1 H NMR (300 MHz,
CD3SOCD3): d 0.12 (s, 6 H, (CH3)2Si), 0.18 (s, 6 H, (CH3)2Si), 0.85
(t, 3 H, CH3), 0.89 (s, 9 H, t-Bu), 0.94 (s, 9 H, t-Bu), 1.14 (t, 3 H,
J =7.1 Hz, OCH2CH3), 2.35 (q, 2 H, CH2), 4.10 (q, 2 H, J = 7.1Hz,
OCH2CH3), 4.60 (s, 2 H, OCH2), 6.54 (d, 2 H, J = 8.9Hz, C6H4), 6.63
(d, 2 H, J = 8.6Hz, C6H4), 6.68 (d, 2 H, J = 8.9Hz, C6H4), 6.82 (d, 2 H,
J = 8.5 Hz, C6H4), 6.94 (d, 2 H, J = 8.6Hz, C6H4), 7.02 (d, 2 H,
J = 8.5 Hz, C6H4). 13C NMR (75.5MHz, CD3SOCD3): d ꢁ4.5 (Si(CH3)2),
13.3 (CH3), 13.9 (OCH2CH3), 17.9 (Cq of t-Bu), 25.5 (CH3 of t-Bu), 28.4
(CH2), 60.5 (OCH2), 64.5 (OCH2CH3), 113.3, 119.4 (2C), 130.2, 130.4
and 131.3 (CHarom), 134.9, 136.0, 137.0, 137.5, 140.2, 153.0, 153.5 and
155.4 (Cq of 3 C6H4 and C═C), 168.6 (C═O). IR (CH2Cl2, n cmꢁ1):1755
+
•
661 [M] . Elemental analysis calcd for C38H55NO5Si2 C,68 .94; H,
+
(CO), 1604 cmꢁ1 (C═C). MS (EI): m/z: 646 [M] ). Elemental analysis
•
8.37. Found: C,68.65; H, 8.62.
calcd for C38H54O5Si2 C, 70.54; H, 8.41. Found: C, 70.58; H, 8.46.
O
Compound E-8
26
O
7
8
The reaction was carried out at ꢁ10 ꢂC under argon. Compound
E-7 (770 mg, 1.19 mmol) was dissolved in distilled dichloro-
methane (15 ml) and cooled to ꢁ10 ꢂC. HNMe(OMe)–HCl
(464 mg, 4.76 mmol) was added. Then, AlMe3 (2.38 ml, 4.76 mmol,
2.5 M in toluene) was added dropwise (10 min). After stirring for
2 h 30 min, the mixture was diluted with CH2Cl2 (100 ml), washed
with water (2 ꢃ 30 ml), dried over MgSO4 and filtered. After
concentration under reduced pressure, the crude product was
chromatographed on a silica gel column using diethyl ether–
pentane (2:1) as the eluent. Compound E-8 was obtained as a
colourless oil (562 mg, 71% yield). Rf = 0.5, diethyl ether–pentane,
2:1). 1 H NMR (300 MHz, CDCl3): 0.16 (s, 6 H, (CH3)2Si), 0.22 (s, 6 H,
(CH3)2Si), 0.88 (t, 3 H, CH3 of Et), 0.92 (s, 9 H, CH3 of t-Bu), 0.96 (s,
9 H, CH3 of t-Bu), 2.43 (q, 2 H, J = 7.2 Hz, CH2 of Et), 3.23 (s,3 H,
CH3 of N-CH3), 3.7 (s, 3 H, OCH3), 4.67 (s, 2 H, CH2 of OCH2), 6.58
(d, 2 H, J = 8.7 Hz, C6H4), 6.64 (d, 2 H, J = 8.7 Hz, C6H4), 6.72
(d, 2 H, J = 8.7 Hz, C6H4), 6.79 (d, 2 H, J = 8.7 Hz, C6H4), 6.94
(d, 2 H, J = 8.7 Hz, C6H4), 7.06 (d, 2 H, J = 8.7 Hz, C6H4). 13C NMR
(75.5 MHz, CDCl3): d ꢁ4.4 (Si(CH3)2), 13.6 (CH3), 18.1 and 18.2 (Cq
of t-Bu), 25.7 (CH3 of t-Bu), 28.9 (CH2), 32.4 (NMe), 61.6 (NOMe),
65.6 (OCH2), 113.5, 119.5, 119.6, 130.6, 130.7 and 131.9 (CHarom),
24
25
23
6
9
3
2
4
5
10
11 12
1
22
17
16
18
13
14
21
20
19 15
Si
O
O
Si
Z-7
Second fraction: isomer Z-7 (1.758 g, white solid; 27% yield; m.p.
106 ꢂC). Rf = 0.39, diethyl ether–pentane, 1:10). 1 H NMR (400 MHz,
CDCl3): d 0.11 (s, 6 H, (CH3)2Si), 0.16 (s, 6 H, (CH3)2Si), 0.92 (t, 3 H,
J =7.4 Hz, CH3), 0.92 (s, 9 H, t-Bu), 0.96 (s, 9 H, t-Bu), 1.31 (t, 3 H,
J = 7.1 Hz, H26), 2.43 (q, 2 H, J = 7.4Hz, H3), 4.29 (q, 2 H, J = 7.1Hz,
H25), 4.63 (s, 2 H, H23), 6.47 (d, 2 H, J = 8.6Hz, H13 +H15), 6.62
(d, 2 H, J = 8.6Hz, H19 + H21), 6.68 (d, 2 H, J = 8.6 Hz, H12 + H16),
6.87 (d, 2 H, J = 8.6Hz, H7 + H9), 6.93 (d, 2 H, J = 8.6 Hz, H18 + H22),
7.13 (d, 2 H, J = 8.6Hz, H6 + H10). 13C NMR (100.62 MHz, CDCl3):
d ꢁ4.4 (Si(CH3)2), 13.8 (C1), 14.2 (C26), 18.2 and 18.3 (Cq of t-Bu),
Appl. Organometal. Chem. 2013, 27, 28–35
Copyright © 2012 John Wiley & Sons, Ltd.
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T. Dallagi et al.
135.5, 136.8, 136.9, 137.2, 140.8, 153.7, 154.2 and 156.0 (Cq of 3
Isomerization
C6H4 and C═C), 167.0 (C═O). IR (CH2Cl2, cmꢁ1): 1692.4 (CO),
E-2 was dissolved in acetone and left for 4 days at room temper-
ature. The proportion between E/Z isomers reached a value of 58/
42, determined by NMR: 1 H NMR (300 MHz, CD3COCD3) of Z-2
from the (E + Z)-2 spectrum: d 0.87 (t, 3 H, J = 7.4 Hz, CH3), 2.41
(q, 2 H, J = 7.4 Hz, CH2), 4.94 (s, 2 H, OCH2), 5.16 (t, 2 H, J = 2.1 Hz,
C5H4), 5.81 (t, 2 H, J = 2.1 Hz, C5H4), 6.65 (d, 2 H, J = 8.8 Hz, C6H4),
6.65 (d, 2 H, J = 8.8 Hz, C6H4), 6.81 (d, 2 H, J = 8.8 Hz, C6H4), 6.82
(d, 2 H, J = 8.4 Hz, C6H4), 6.95 (d, 2 H, J = 8.8 Hz, C6H4), 7.03 (d,
2 H, J = 8.4 Hz, C6H4), 8.17 and 8.31 (s, s, OH, OH). 13C NMR
(75.5 MHz, CD3COCD3): d 14.0 (CH3), ffi 29.8 (CH2, overlap
CD3COCD3), 71.5 (OCH2), 85.5 and 88.3 (CH, C5H4), 90.0 (Cip,
C5H4), 114.2, 115.1, 115.6, 115.8, 131.3, 131.6 and 132.7 (CHarom),
134.3, 136.0, 138.2, 138.3, 141.4, 156.1, 156.5 and 157.3 (Cq of 3
C6H4 and C═C), 193.3 (C═O), 223.0 (MnCO). (Z + E)-2: m.p.
120 ꢂC. IR (CH2Cl2, cmꢁ1): 2033 and 1951 (Mn(CO)), 1701
and1682 (CO), 1608 cm-1 (C═C). HRMS (TOF MS ESI, C32H24MnO7:
[M–H]ꢁ) calcd: 575.0902; found: 575.0920.
+
•
1603.7 (C═C). MS (EI) m/z : 661 [M] . Elemental analysis calcd.
for C38H55NO5Si2 C, 68.94; H, 8.37 ; N, 2.12. Found: C, 68.35; H,
8.47; N, 2.04.
Compound Z-6
CpMn(CO)3 (735 mg, 3.6 mmol) was dissolved in anhydrous THF
(10 ml). The solution was cooled at ꢁ70 ꢂC, then nBuLi (1.68 ml,
2.7 mmol, 1.6 M solution in hexane) was added (2 min). The reac-
tion mixture was stirred for 1 h 30 min and the temperature
raised from ꢁ70 ꢂC to ꢁ30 ꢂC. A solution of compound Z-8
(597 mg, 0.9 mmol) in THF (5 ml) was then added (2 min). The so-
lution was stirred for 10 min at ꢁ30 ꢂC, after which 30 ml of 1/10
HCl solution was added and the cold bath was removed. After
5 min, 30 ml of 1/10 HCl solution was added and the product
was extracted with 3 ꢃ 50 ml diethyl ether. The organic layer
was washed with 2 ꢃ 40 ml water and was dried over MgSO4
and filtered. After concentration under reduced pressure, the
crude product was chromatographed on a silica gel column using
diethyl ether–pentane (2:1) as the eluent. Unreacted CpMn(CO)3
was first eluted (510 mg). The second fraction was identified as
compound Z-6 (160 mg; 22% yield; m.p. 122 ꢂC). Rf = 0.78, dietyl
ether:pentane, 2:1). 1 H NMR (300 MHz, CD3COCD3): d 0.13
(s, 6 H, (CH3)2Si), 0.18 (s, 6 H, (CH3)2Si), 0.92 (t, 3 H, J = 5.6 Hz,
CH3), 0.94 (s, 9 H, t-Bu), 0.97 (s, 9 H, t-Bu), 2.45 (q, 2 H, J = 5.6 Hz,
CH2), 5.12 (s, 2 H, OCH2), 5.21 (t, 2 H, J = 1.7 Hz, C5H4), 5.88 (t, 2 H,
J = 1.7 Hz, C5H4), 6.53 (d, 2 H, J = 6.4 Hz, C6H4), 6.68 (d, 2 H,
J = 6.4 Hz, C6H4), 6.73 (d, 2 H, J = 6.4 Hz, C6H4), 6.99 (d, 4 H,
J = 6.4 Hz, C6H4), 7.17 (d, 2 H, J = 6.4 Hz, C6H4). 13C NMR
(75.5 MHz, CD3COCD3): d ꢁ4.4 (Si(CH3)2), 13.8 (CH3), 18.6 and
18.7 (Cq of t-Bu), 25.9 (CH3 of t-Bu), 29.3 (CH2), 71.5 (OCH2), 85.5
and 88.3 (CH, C5H4), 90.0 (Cip, C5H4), 115.1, 119.7, 120.3, 131.3,
131.6 and 132.6 (CHarom), 136.3, 137.6, 137.8, 138.5, 141.7, 154.4,
154.8 and 157.8 (Cq of 3 C6H4 and C═C), 193.3 (C═O). IR (CH2Cl2,
cmꢁ1): 2033 and 1952 (Mn(CO)), 1702 and 1679 (CO). MS (CI):
Cell Culture and Cell Proliferation Assay
The breast adenocarcinoma cell lines MDA-MB-231 and MCF7 were
obtained respectively from ATCC and Dr Matthias Kassack (Bonn,
Germany). Cells were grown in RPMI medium supplemented with
10% fetal calf serum, in the presence of penicillin, streptomycin
and fungizone in 75cm2 flask under 5% CO2. Cells were plated in
96-well tissue culture plates in 200 ml medium and treated 24 h later
with 2 ml stock solution of compounds dissolved in DMSO using a
Biomek 3000 (Beckman-Coulter). Controls received the same
volume of DMSO (1% final volume). After 72 h exposure, MTS
reagent (Promega) was added and incubated for 3 h at 37ꢂC;
absorbance was monitored at 490nm and results expressed
as the inhibition of cell proliferation calculated as the ratio
[(1-(OD490 treated/OD490 control)) ꢃ 100] in triplicate experi-
ments. For IC50 determination (50% inhibition of cell proliferation),
cells were incubated for 72 h following the same protocol with
compound concentrations ranging from 5 nM to 100 mM in separate
duplicate experiments.
+
•
m/z = 805 [MH] . Elemental analysis calcd for C44H53MnO7Si2: C,
65. 65 ; H, 6.64. Found: C, 65.78; H, 6.60.
Acknowledgements
Compound Z + E-2
This research was supported by the Ministère de la Recherche et le
Centre Nationale de la Recherche Scientifique. We thank M.-N.
Rager for the identification of Z-7 structure by 2D-NMR technique.
This work has benefited from the facilities and expertise of the
Small Molecule Mass Spectrometry platform of IMAGIF (Centre de
Recherche de Gif; http://www.imagif.cnrs.fr).
Compound Z-6 (130 mg, 0.16 mmol) was dissolved in ethanol
(10 ml). 0.2 ml concentrated HCl was added. The mixture was
stirred at 80 ꢂC for 15 min. The oil bath was removed and 50 ml
diethyl ether was added. The mixture was washed with water
(3 ꢃ 10 ml) and dried over MgSO4. After concentration under re-
duced pressure, the crude product was chromatographed on sil-
ica gel column using diethyl ether–pentane (4:1) as the eluent to
furnish E-2 as a yellow solid (48 mg, 48% yield). Rf = 0.50 (diethyl
ether–pentane, 4:1). 1 H NMR (300 MHz, CD3COCD3): d 0.92 (t,
3 H, J = 7.4 Hz, CH3), 2.45 (q, 2 H, J = 7.4 Hz, CH2), 5.10 (s, 2 H,
OCH2), 5.20 (t, 2 H, J = 2.1 Hz, C5H4), 5,87 (t, 2 H, J = 2.1 Hz, C5H4),
6.49 (d, 2 H, J = 8.5 Hz, C6H4), 6.64 (d, 2 H, J = 8.5 Hz, C6H4), 6.70
(d, 2 H, J = 8.5 Hz, C6H4), 6.96 (d, 2 H, J = 8.5 Hz, C6H4), 6.98 (d,
2 H, J = 8.6 Hz, C6H4), 7.15 (d, 2 H, J = 8.6 Hz, C6H4), 8.08 and 8.15
(s, s, OH, OH). 13C NMR (75.5 MHz, CD3COCD3): d 14.0 (CH3), ffi
29.8 (CH2, overlap with CD3COCD3), 71.5 (OCH2), 85.5 and 88.3
(CH, C5H4), 90.0 (Cip, C5H4), 114.2, 115.1, 115.6, 115.8, 131.3,
131.6 and 132.7 (CHarom), 134.3, 135.8, 138.2, 138.3, 141.3, 156.1,
156.5 and 157.7 (Cq of 3 C6H4 and C═C), 193.3 (C═O), 223.0
(MnCO).
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