Synthesis and antiproliferative activity of novobiocin analogues as potential hsp90 inhibitors Dedicated to the memory of Dr. Christine Radanyi.

Article abstract of DOI:10.1016/j.ejmech.2014.06.067

A series of substituted coumarins1-10 was designed and synthesized as a novel class of 4TCNA analogues. Compound 2a showed excellent antiproliferative activity with mean GI₅₀ values at a micromolar level in a diverse set of human cancer cells (

Full text of DOI:10.1016/j.ejmech.2014.06.067

Accepted Manuscript
Synthesis and Antiproliferative Activity of Novobiocin Analogues as Potential Hsp90
Inhibitors
Davide Audisio, Délphine Methy-Gonnot, Christine Radanyi, Jack-Michel Renoir,
Stéphanie Denis, Félix Sauvage, Juliette Vergnaud-Gauduchon, Jean-Daniel Brion,
Samir Messaoudi, Mouad Alami
PII:
S0223-5234(14)00596-0
10.1016/j.ejmech.2014.06.067
EJMECH 7110
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 18 March 2014
Revised Date: 13 June 2014
Accepted Date: 28 June 2014
Please cite this article as: D. Audisio, D. Methy-Gonnot, C. Radanyi, J.-M. Renoir, S. Denis, F. Sauvage,
J. Vergnaud-Gauduchon, J.-D. Brion, S. Messaoudi, M. Alami, Synthesis and Antiproliferative Activity of
Novobiocin Analogues as Potential Hsp90 Inhibitors, European Journal of Medicinal Chemistry (2014),
doi: 10.1016/j.ejmech.2014.06.067.
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ACCEPTED MANUSCRIPT
Graphical abstract
Synthesis and Antiproliferative Activity of Novobiocin Analogues as
Potential Hsp90 Inhibitors
Davide Audisio[a], Délphine Methy-Gonnot[b], Christine Radanyi[b], Jack-Michel Renoir[b,c], Stéphanie
Denis[b], Félix Sauvage[b], Juliette Vergnaud-Gauduchon[b], Jean-Daniel Brion[a], Samir Messaoudi*[a],
Mouad Alami*[a]

ACCEPTED MANUSCRIPT
Synthesis and Antiproliferative Activity of Novobiocin
Analogues as Potential Hsp90 Inhibitors
Davide Audisio[a], Délphine Methy-Gonnot[b], Christine Radanyi[b], Jack-Michel Renoir[b,c]
,
Stéphanie Denis[b], Félix Sauvage[b], Juliette Vergnaud-Gauduchon[b], Jean-Daniel Brion[a],
Samir Messaoudi* [a], Mouad Alami*[a]
a
University Paris-Sud, CNRS, BioCIS-UMR 8076, Laboratoire de Chimie Thérapeutique, Equipe Labellisée Ligue Contre Le
Cancer, LabEx LERMIT, Faculté de Pharmacie, 5 rue J.-B. Clément, Châtenay-Malabry, F-92296, France.
b Institut Galien-Paris Sud, CNRS, UMR 8612, Faculté de Pharmacie, 5 rue J.-B. Clément, Châtenay-Malabry, F-92296, France.
c Present address, INSERM U749, Institut Gustave Roussy, 114 rue Edouard Vaillant, Villejuif, F94805, France.
Corresponding authors. Tel.: +33 1 46 83 58 47. Fax: +33 1 46 83 58 28. Email: samir.messaoudi@u-psud.fr (S.M.) or
mouad.alami@u-psud.fr (M.A.)
Dedicated to the memory of Dr. Christine Radanyi
Abstract
A series of substituted coumarins 1-10 was designed and synthesized as a novel class of 4TCNA analogues. Compound
2a showed excellent antiproliferative activity with mean GI50 values at a micromolar level in a diverse set of human
cancer cells (GI50 = 2-30 µM) and induced a high apoptosis level in MCF-7 breast cancer cell line. The molecular
signature of hsp90 inhibition was assessed by depletion of the Erα hsp90 client protein.
Keywords: Hsp90, 4TCNA, 6BrCaQ, cytotoxicity, apoptosis.
1

ACCEPTED MANUSCRIPT
1. Introduction
Hsp90 is an emerging therapeutic target of interest for the treatment of cancer[1,2,3,4,5] and other diseases.[6, 7] As a
chaperone protein, hsp90 is responsible for the conformational maturation of more than 250 hsp90-dependent client
proteins which are directly associated with all hallmarks of cancer.[8, 9, 10, 11] The ATP binding site at the N-terminal
domain of hsp90 has been extensively studied (especially following its cocrystallisation in the presence of
geldanamycin) and the protein function may be inhibited by molecules competing with ATP binding, resulting in
destabilization of the hsp90 client-protein heteroprotein complex, which leads to proteasome-mediated oncogenic client
protein degradation.[12] Several structurally distinct hsp90 inhibitors are currently being evaluated for anticancer
activity in numerous Phase II and several Phase III clinical trials, however, detriments such as heat shock induction and
cytostatic activity associated with N-terminal inhibition has limited their potential use against cancer.[8]
The C-terminal domain of hsp90 has been implicated biochemically as the site of a possible second, cryptic ATP-
binding site on the protein. Its contribution to the overall regulation of chaperone function is not clear, but some small
molecules that bind to the C-terminal domain such as the antibiotic novobiocin[13] (Nvb, Figure 1), do not induce the
pro-survival heat shock response, and in some cases, even cause hsp70 and hsp90 degradation.[14, 15] Novobiocin
exhibit its antitumor activity against human breast SKBr3 cancer cell lines (~700 µM) through hsp90 inhibition. [16] It
binds with poor affinity, and induces hsp90 client proteins degradation in a concentration-dependent manner. Although
no cocrystal structure of hsp90 bound to C-terminal inhibitors has been reported, the structure and function of the hsp90
C-terminal binding site are under intense investigation. A better understanding of the role of this putative hsp90 C-
domain site in regulating the function of the chaperone, as well as its potential as an anticancer drug target, requires
further investigations. The identification of more potent site-specific inhibitors is needed and has led the development of
specific C-terminal hsp90 inhibitors as potential anticancer drug modalities.
In this context, we reported a novel series of simplified 3-aminocoumarin analogues related to Nvb as a class of
highly potent hsp90 inhibitors. We demonstrated that removal of the noviose moiety together with introduction of a
tosyl substituent at C-4 coumarin nucleus lead to 4TCNA (Figure 1)[17, 18, 19, 20, 21] as a lead compound. In the
pursuit of the development of more potent novobiocin analogues, we recently reported derivatives that contain a
quinolein-2-one moiety in lieu of the coumarin unit. From these structure-relationship activity (SAR) studies, 6BrCaQ
(Figure 1) [22, 23, 24] was found to be a potent derivative displaying the following IC50 values: 7 µM against MCF7
cells, 2 µM against MDA MB231 cells, 8 µM against Caco2 cells, 5 µM against IGROV-1 cells and 2 µM against
ISHIKAWA cells. Further studies on its mode of action revealed that 6BrCaQ manifests downregulation of several
hsp90 client proteins (HER2, Raf-1 and cdk-4), induces a high apoptosis level in MCF-7 breast cancer cell line
(activation of caspases 7, 8 and 9) and promotes the subsequent cleavage of poly(ADP-ribose) polymerase (PARP)
suggesting stimulation of apoptosis through both extrinsic and intrinsic pathways. In addition to these outstanding pro-
apototic properties, 6BrCaQ was found to mediate cell death in a p23-dependant process and through a number of
pathways in wich autophagy has a prominent place.[22]
Because of this novel and exciting activity, it was proposed that complementary 4TCNA analogues, built upon an
optimized novoboicin scaffold could lead to more efficacious compounds. Herein, we planned to prepare a new series
of analogues (Figure 1), in which various chemical modifications at the C-4, C-6 and C-7 positions of 4TCNA were
performed in the aim to better understand the SAR in this novel series. In this article the synthesis and the biological
2

evaluation of novel 4TCNA analogues 1-10 are described. Preliminary in vitro efficacy of these compounds in terms of
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cytotoxicity, apoptosis and hsp90 client proteins degradation is reported.
Figure 1. Structures of novobiocin, synthetic derivatives, 4TCNA, 6BrCaQ and targeted molecules.
Figure 1.
2. Results and discussion
2.1. Chemistry.
The synthesis of the target coumarin structures 1-10 is summarized in Scheme 1. Cyclonovobiocic acid (CNBA) was
prepared as it was previously reported [17] by acidic hydrolysis of commercially available monosodium novobiocin
salt. To extend upon our knowledge of 4TCNA and its SAR, several (hetero)aryl and alkyl sulfonyl moieties were
appended to the 4-position of the coumarin ring of CNBA. Chemistry developed in our lab was used to attach
selectively the desired sulfonyl substituents at C-4 postion rather than C-7 one.[17] Thus, treatment of CNBA with
pyridine followed by substituted sulfonylchloride derivatives gave the best results for the C-4 sulfonylation process.
Accordingly, the desired C-4-sulfonylated analogues 1a-e were selectively obtained in acceptable yields (~50%).
In another strategy, we wished to introduce a carbohydrate group at the 7-position of 4TCNA to further increase both
solubility and polarity and to explore hydrogen bonding interactions. Numerous biologically active natural and non-
natural products contain carbohydrates appended to their scaffolds that serve to increase solubility and provide
interactions with their cognate receptor.[25, 26, 27, 28, 29] To this end, O-glycosylated 4TCNA 2a derivative was
prepared as described in scheme 1, by coupling the readily available α-glycopyranoside with the remaining phenol
function of 4TCNA under Mitsunobu’s conditions (DIAD, PPh3 in THF).[30, 31, 32, 33, 34] The tosyl group of 2a was
then substituted by a free amine function by the use of ammonia in THF at RT affording the β-glycosylated derivative
10.
For direct comparison to 6BrCaQ[22] in which the bromine atom at C-6 position play an important role for its activity,
brominated 4TCNA derivative 9 was synthesized through a regioselective bromination by using bromine in AcOH at
RT. The 6-bromo 4,7-dimethoxylated CNBA derivative 3 was also prepared in a good overall yield by selective
bromination of the C-6 position using MPHT as the brominating agent[35, 36] (92% yield) followed by alkylation of
both free C-4 and C-7 hydoxyl groups of CNBA by using an excess of dimethyl sulfate and K2CO3 (62% yield). The C-
3

Br bond in 3 was then used for further functionalizations. In order to evaluate the importance of the C-6 position
ACCEPTED MANUSCRIPT
substitution in 4TCNA, we planned to introduce an alkynyl and aryl substituent by metal-catalyzed cross coupling
reaction. For this purpose, treatment of compound 3 under Sonogashira conditions (CuI, PdCl2(PPh)2, PPh3 in
DMF/Et2NH) allowed the introduction of various alkynes at the C-6 position of 3 together with a concomitant
deprotection of the methoxy group at the C-4 position. The compound 6 bearing a 4-methoxyphenyl group at C-6
position was prepared in a 86% yield by using the same strategy using a Suzuki cross coupling reaction between 3 and
4-methoxyphenylboronic acid. Subsequent tosylation of the free hydroxyl group of 4a-e and 6 under our previously
reported protocol led to a series of derivatives 5a-f and 7 in 55-84% yields.[17, 22] Finally, the aminoethylmorpholine
group which is present in a plethora of biologically active compounds[37, 38, 39, 40, 41] was introduced in 4TCNA by
nucleophilic displacement of the tosyl group by aminoethylmorpholine in dioxane providing compound 8 in a 71%
yield.
Scheme 1. Synthesis of compounds 1-10.
O
O
O
OH
O
O
O
O
O
S
O
R1
S
O
O
O
R1
Cl
OAc
AcO
AcO
OH
OTs
OH
(a)
(c)
(1.1 equiv)
(b)
NH
O
NH
O
NH
O
NH
O
O
AcO
AcO
AcO
AcO
HO
O
HO
O
O
O
O
O
O
Me
Me
Me
Me
Novobiocin (Nvb)
CNBA
2a
O
AcO
MeO
OH
1a: R1 = tolyl (4TCNA)
1b: R1 = methyl
H2NOCO
OH
1c: R1 = thienyl
1d: R1 = naphtyl
1e: R1 = 7ꢀquinolinyl
(j)
(d)
O
(g)
(i)
N
NH2
O
O
O
O
O
O
O
N
O
O
R1
OH
OMe
NH
NH2
OAc
AcO
AcO
NH
O
Br
NH
O
NH
NH
(e)
O
AcO
MeO
O
MeO
O
3
HO
O
O
8
O
O
O
Me
Me
Me
Me
10
4a: R1 = Ph
4b: R1 = 4(OMe)Ph
4c: R1 = 3,4,5(OMe)Ph
4d: R1 = Me3Si
4e: R1 = (Me)2NCH2
4f: R1 = H
(f)
O
O
(b)
MeO
O
O
OH
OTs
(h)
NH
Br
NH
MeO
O
O
HO
O
O
9
Me
Me
6
O
O
R1
OTs
(b)
NH
O
MeO
O
O
Me
5a: R1 = Ph
5b: R1 = 4(OMe)Ph
MeO
O
OTs
5c: R1 = 3,4,5(OMe)Ph
5e: R1 = (Me)2NCH2
5f: R1 = H
NH
O
MeO
O
Me
7
aReagents and conditions: (a) HCl (12 M), EtOH, reflux, 1 h (b) Pyridine, 0° C to RT, 2.5 h. (c), DIAD (2 equiv), PPh3 (2 equiv), THF, -78 °C to RT,
24 h (d) (i) MPHT (2 equiv), MeCN, 80 °C, 16 h (ii) K2CO3 (6 equiv), Me2SO4 (6 equiv), DMF, RT, 12 h, (e) PdCl2(PPh3)2 (6 mol%), CuI (6 mol%),
alkyne (1 equiv), PPh3 (20 mol%), DMF/Et2NH (1:3), 120 °C, 30 min; (f) (i) Pd(OAc)2 (5 mol%), Xphos (20 mol%), KF (3 equiv), THF, reflux, 24 h
(ii) DMF/Et2NH (1:3), 120 °C, 30 min. (g) Dioxane, sealed tube, 100 °C. (h) K2CO3 (2 equiv), MeOH, RT, 2 h. (i) Br2, AcOH, 24 h, RT. (j) NH3
(gas), THF, RT, 24 h.
4

1, 3, 5 and 7A-10CCEPTED MANUSCRIPT
Table 1. Cytotoxic effect of
derivatives against MCF-7 cell line
Compounds
Viab. [%][a]
Compounds
Viab. [%][a]
Compounds
Viab. [%][a]
36
10
96
1a (4TCNA)
2a
5e
61
62
33
22
90
90
89
92
82
89
87
65
1b
1c
1d
3
5f
5a
5b
7
8
1e
5c
9
ND
10
71
Novobiocin
6BrCaQ
10
[a] Value of the anti-proliferative effect (% of viable cells compared to untreated cells 100%) of analogues 1, 3, 5 and 7-10 in MCF-7
cell line at a concentration of 10-4 M (MTT method). ND: Not determined
2.2. Biological results.
Upon completion of their syntheses, the in vitro activity of coumarin derivatives 1, 3, 5 and 7-10 was evaluated by
their growth-inhibitory potency in MCF-7 cell line at concentration of 10-4 M. The quantification of cell survival in this
cell line was established by using MTT assays after 72 h exposure (Table 1), and GI50 values were determined at the
concentration required to produce 50% inhibition (Table 1).
As shown in Table 1, compounds 1b and 1c bearing a mesityl and thienylsulfonyl groups, respectively, at C-4
position of the coumarin moiety displayed slight effect in the growth of MCF-7 cells (61% and 62% survival,
respectively), while compounds 1d and 1e with a naphtylsulfonyl and 7-quinoleinesulfonyl, respectively, were able to
decrease the cell viability in MCF-7 cells until 22-33% compared to the reference compound 4TCNA (36% survival)
indicating a possible π-staking interactions of the bulky aromatic substituents at the C-4 position with the binding
5

pocket. Another important observation is that β−glycosylated-4TCNA (2a) induced a significant decrease of the cell
ACCEPTED MANUSCRIPT
viability in MCF-7 cells (10% survival) while analogue 10 affects slightly the growth of MCF-7 cells (71% survival).
These results clearly suggest that the presence of the β−(ΟAc)-glucose at the C-7 position of the coumarin nucleus and
a tosyl group at the C-4 position are very important to affect cell viability (Table 1). A comparison of 6BrCaQ with 6-
bromocoumarin derivative 9 (6Br-4TCNA) revealed that introduction of bromine atom at C-6 position of the coumarin
nucleus induced a significant increase of the cell viability in MCF-7 cells (65% survival, respectively) vs 33% survival
for 4TCNA and 10% survival for 6BrCaQ. In addition, substitution of the C-6 position by alkynyl- or aryl substituents
did not produce compounds that inhibit cell growth more effectively (see compounds 5a-f and 7 , survival > 80%) than
the reference compound 4TCNA (1a, 33%) suggesting that functionalization of the position 6 of 4TCNA with and aryl
or alkynyl appendage significantly alters the mode of binding.
Then, the growth inhibitory activities against MCF-7 breast cancer cell line were measured for the selected coumarins
derivatives (1a, 1d-e and 2a). All the compounds shown in Table 2 behave as stronger cell growth inhibitors in regard to
Nvb. Compounds 1d and 1e having a naphtylsulfonyl and quinoleinsulfonyl groups at the C-4 position exhibited
approximatively a same growth inhibition activity than that of 4TCNA, which itself is ~4x more active than Nvb.
Interestingly, 2a having a O-glycoside group at the C-7 position of the coumarin nucleus showed a significant ability to
inhibit cell growth and is ~40-fold more potent than the parent compound Nvb, 4-fold more active than 4TCNA (1a)
and displays the same activity than that of our best lead compound 6BrCaQ (GI50 = 7 µM). This result suggests that
activity increased as hydrogen bond donor/acceptor, polarity and solubility properties of the inhibitor increased.
Table 2. GI50 (µM) values for anti-proliferative effects of
selected compounds 1a, 1d-e and 2a[a] against breast cancer
cell lines (MCF-7)[b]
MCF-7 (µM)
Compound
50
67
64
6
1a (4TCNA)
1d
1e
2a
7
6BrCaQ
260
Novobiocin (Nvb)
[a]
GI50 is the concentration of compound needed to reduce cell
growth by 50% following 72 h cell treatment with the tested drug
(average of three experiments). Values are means of three
experiments, carried out in sextuplate.[b] MCF-7, human breast
cancer cells.
To further characterize the cytotoxicity profiles of these compounds, we next investigated the effect of the most
active compound 2a on the proliferation of six tumor cell lines hormone-independent breast cancer (MDA-MB-231),
human breast cancer cells resistant to Tamoxifen (MCF7 TamoxifenR), human breast cancer cells resistant to
Fulvestrant (MCF-7 FaslodexR), human myeloma (plasmatocytoma) cells (RPMI 8226 and LP-1) and prostate cancer
cells (PC-3). The results of this study, summarized in Table 3, revealed that compound 2a, as 6BrCaQ, strongly
inhibited the growth of all examined tumor cell lines with GI50 ranging from 2 to 30 µM, and this effect did not depend
on the cell type. The RPMI 8226 and LP-1 cancer cell lines were significantly more sensitive (GI50 ~ 2-5 µM), while
MCF-7 TamoxifenR, MCF7 FaslodexR, and PC-3 cancer cell line were less responsive (GI50 ~ 25-30 µM) to growth
inhibition by 2a. Consequently, O-glycosylation at 7-position of the coumarin core appears to be a suitable moiety in
this series for antiproliferative activities.
6

ACCEPTED MANUSCRIPT
Table 3. Cytotoxicity (GI50 µM, 72 h) a
Compounds
MCF-7
MDA-MB-231c
MCF-7
MCF-7
RPMI 8226
LP-1
PC-3
TamoxifenR
FaslodexR
2a
6
7
10
2
30
25
2.5
5
5
25
10
6BrCaQ
ND
ND
6.2
[a]
GI50 is the concentration of compound needed to reduce cell growth by 50% following 72 h cell treatment with the tested
drug (average of three experiments). Values are means of three experiments, carried out in triplicate or sextuplate. [b] MCF-7:
human breast cancer cells. MCF7 TamoxifenR human breast cancer cells resistant to Tamoxifen. MCF7 FaslodexR: human
breast cancer cells resistant to Foslodex. MDA-MB231: hormone-independent breast cancer. RPMI 8226 and LP-1 : human
myeloma cells. PC-3: human prostate cancer cells. ND. not determined
To gain further insight in the mechanism of action, the most cytotoxic compound 2a was assayed for its effect on cell
cycle distribution. The results presented in Table 4, demonstrate that highly increased accumulation of MCF-7 cells in
the G2/M phase of the cellular cycle was observed after treatment with 2a (55% as compared to 7.0% in the control).
Prolonged incubation with compound 2a (72 h) increases G2/M phase up to 60%. SubG1 phase, which represents
apoptotic or necrotic cells, was found to be also increased until 27% upon 2a exposure for 72 h treatment than in the
control (9.5%). All these data reveal 2a to be a more potent inducer of G2/M arrest than other 4TCNA derivatives in
MCF-7 cells while 6BrCaQ remains the strongest inducer of apoptosis.
Table 4. Cell cycle and apoptosis analysis of MCF-7 cells treated with analogue 4TCNA,
6BrCaQ and 2a (100 µM) for 48 h and 72 h.[a]
Sub G1
G0/G1 (%)
S (%)
G2/M (%)
compound
48 h
72 h
48 h
72 h
48 h
72 h
48 h
72 h
19.0
27.5
41.5
DMSO
4TCNA
6BrCaQ
2a
5
6
9.5
87
60.5
6
20.5
35.5
7
30.5
36.0
47.0
44.0
34.81
37.0
25.5
48.0
29.5
40.43
17.14
18.09
13
27
40
30.0
5.5
9.5
55
60.0
[a] Data represent percentage of cells in Sub G1 and G2/M phases of the cell cycle. The results
are the mean of two independent experiments in which no more than 2.5 variations were
measured.
In order to confirm that the introduction of a glucose moiety at 7-postion of 4TCNA did not alter inhibitory activity
against hsp90, MCF-7 cells were exposed to various compounds (24 h at 100 µM) in the presence or not of the
proteasome inhibitor MG132, then western blot analyses of cell lysates. Given that inhibition of hsp90 leads to a
proteasome–mediated degradation of client proteins, we wondered at first, if the selected compounds could affect the
stability of the transcription factor ER which is an hsp90-client protein. As shown in Figure 2A, 2a is able to induce a
proteasome-mediated loss of ERα protein in the same manner than 4TCNA (Figure 2B), suggesting inhibition of hsp90
and disruption of heteroprotein complexes. The activity of these two compounds was inhibited by MG-132. One can
note that analogues 1d and 1e which displayed GI50 values of 67 to 64 µM, respectively, (Table 2) induced also a
proteasome-mediated ERα degradation (Figure 2C).
A
DMSO
2a
B
4TCNA
DMSO
C
DMSO
1d
1e
MG132
-
+
MG132
-
+
MG132
-
+
-
+
NS
NS
NS
Erα
ERα
Erα
Figure 2 Effects of quinolone analogues 1d, 1e, 2a and 4TCNA on ERα stability. MCF-7 cells were grown and exposed to hsp90 inhibitors (1d, 1e,
2a and 4TCNA, 100 ꢀM) as described in Experimental Section in the presence (+) or absence (−) of the proteasome inhibitor MG132 (5 ꢀM) for 24 h
and cell lysates were analyzed by Western blotting with regard to the levels of ERα. DMSO was used as a control, NS = nonspecific protein band
detected in these conditions and serving as a control of constant protein loading.
7

Finally, to provide evidence that the growth inhibitory activity manifested by 2a resulted from hsp90 inhibition, 2a was
ACCEPTED MANUSCRIPT
evaluated by its ability to induce degradation of other hsp90-dependent client proteins such as Her2, Raf and cdk4.
Unfortunately, 2a proved to be inactive in regard to proteasome-mediated degradation of these selected hsp90-
dependent client proteins. These data suggest that this analogue may selectively affect different other hsp90/client
protein clusters/complexes than 4TCNA and 6BrCaQ as suggested for Celastrol, which preferentially affect hsp90-
cdc37 interaction.[42, 43, 44]
3. Conclusions
We designed and synthesized a series of substituted 4TCNA derivatives 1-10. From these SAR studies, 7-O-
glycosylated 4TCNA (2a) was found to display the most stronger antiproliferative activity against a panel of cancer cell
lines and induces a high apoptosis level in MCF-7 breast cancer cell line. Morever, by contrast to other hsp90 client
proteins (Her2, Raf and cdk4), 2a manifests downregulation of the hsp90 client protein ERα (the key target responsible
for hormone-dependent breast cancer tumor growth).[45] Taken in concert, these data suggest that compounds from this
family of hsp90 inhibitors may target different cluster of Hsp90 client proteins, potentially being targeted not only in
case of hormone-independent and/or –resistant breast cancers but also in other cancers such as multiple myeloma.
4. Experimental
4.1. Chemistry.
4.1.a. General considerations
1
1
The compounds were all identified by usual physical methods, i.e. H-NMR, 13C-NMR, IR, MS. H and 13C NMR
1
spectra were measured in CDCl3 with a Bruker Avance 300 or Bruker Avance 400. H chemical shifts are reported in
ppm from an internal standard TMS or of residual chloroform (7.27 ppm). The following abbreviations are used: m
(multiplet), s (singlet), d (doublet), br s (broad singlet), t (triplet), dd (doublet of doublet), td (triplet of doublet). 13C
chemical shifts are reported in ppm from the central peak of CDCl3 (77.14). IR spectra were measured on a Bruker
Vector 22 spectrophotometer (neat, cm-1). Elemental analyses were performed with a Perkin-Elmer 240 analyser. Mass
spectra were obtained with a LCT Micromass spectrometer. Analytical TLC was performed on Merck precoated silica
gel 60F plates. Merck silica gel 60 (230-400 mesh) was used for column chromatography. Visualization was achieved
with UV light and phosphomolybdic acid reagent unless otherwise stated. Monosodium novobiocin salt was purchased
from Sigma-Aldrich; all other reagents were of high grade and were used without further purification. Analogues
CNBA and 4TCNA were prepared according to our previously reported procedure.[17]
4.1.b. General procedure for the selective C-4 sulfonylation of CNBA.
To a 50 mL ice-cooled round bottom flask charged with CNBA (200 mg, 0.51 mmol, 1 eq.) and pyridine (10 mL), was
added slowly a solution of the corresponding sulfonyl chloride (2.78 mmol, 1.1 eq) in pyridine (5 mL). After 2.5 hrs at
0 °C, the mixture was diluted in AcOEt (25 mL) and the organic phase washed with a 1N HCl solution (6 x 10mL),
dried over Na2SO4, filtered and concentrated under reduced pressure. Further purification on silica gel chromatography
(c-hexane/acétate d’éthyle : 6/4) delivered the corresponding C4-sulfonylated product.
8

4.1.b.1. 3-(2,2-dimethylchroman-6-carboxamido)-7-hydroxy-8-methyl-2-oxo-2H-chromen-4-yl methanesulfonate (1b)
ACCEPTED MANUSCRIPT
After purification, 1b was obtained in 41% yield (98 mg, 0.21 mmol). Rf: 0.14 (c-hexane/AcOEt: 6/4). m.p.: 189-191
°C. 1H-NMR (300 MHz, DMSO-d6, δ): 10.82 (s, 1H), 9.76 (s, 1H), 7.79 (s, 1H), 7.73 (d, 1H, J = 8.4 Hz), 7.51 (d, 1H, J
= 8.8 Hz), 7.01 (d, 1H, J = 8.8 Hz), 6.80 (d, 1H, J = 8.4 Hz), 3.53 (s, 3H), 2.80 (t, 2H, J = 6.4 Hz), 2.21 (s, 3H), 1.81 (t,
2H, J = 6.4 Hz), 1.31 (s, 6H). 13C-NMR (75 MHz, DMSO-d6, δ): 165.3, 159.8, 159.7, 156.9, 152.5, 150.7, 129.9, 127.2,
124.1, 122.1, 120.6, 116.5, 112.8, 112.7, 111.0, 108.1, 75.1, 39.9, 31.7, 26.5 (2C), 21.6, 7.9. MS (ESI+) m/z: 473.9
[M+H]+, 495.9 [M+Na]+. IR (cm-1): 3286, 2931, 1698, 1667, 1636, 1607, 1588, 1489, 1360, 1319, 1255, 1177, 1157,
1138, 1118, 1093, 1022, 947, 822, 665.
4.1.b.2. 3-(2,2-dimethylchroman-6-carboxamido)-7-hydroxy-8-methyl-2-oxo-2H-chromen-4-yl thiophene-2-sulfonat
(1c)
After purification, 1c was obtained in 48% yield (132 mg, 0.24 mmol). Rf: 0.23 (CH2Cl2/AcOEt: 9/1). m.p.: 198-200
°C. 1H-NMR (300 MHz, DMSO-d6, δ): 10.81 (bs, 1H), 9.62 (s, 1H), 8.09-8.07 (m, 1H), 7.89 (dd, 1H, J1 = 3.8 Hz, J2 =
1.4 Hz), 7.61 (s, 1H), 7.57 (d, 1H, J = 8.4 Hz), 7.18 (d, 1H, J = 8.7 Hz), 7.13-7.10 (m, 1H), 6.89 (d, 1H, J = 8.7 Hz),
6.76 (d, 1H, J = 8.4 Hz), 2.80 (t, 2H, J = 6.4 Hz), 2.19 (s, 3H), 1.82 (t, 2H, J = 6.4 Hz), 1.32 (s, 6H). 13C-NMR (75
MHz, DMSO-d6, δ): 164.7, 159.7, 159.5, 156.7, 151.8, 150.5, 137.5, 136.6, 133.6, 129.9, 128.3, 127.2, 124.1, 121.4,
120.3, 116.2, 113.4, 112.6, 111.1, 107.7, 75.0, 31.8, 26.5 (2C), 21.6, 7.9. MS (ESI+) m/z: 564.1 [M+Na]+. IR (cm-1):
1696, 1582, 1490, 1357, 1256, 1193, 1016, 731, 703, 672, 604, 579.
4.1.b.3. 3-(2,2-dimethylchroman-6-carboxamido)-7-hydroxy-8-methyl-2-oxo-2H-chromen-4-yl naphthalene-2-sulfonate
(1d)
1
After purification, 1d was obtained in 49% yield (146 mg, 0.25 mmol). Rf: 0.30 (Et2O). m.p.: 192-194 °C. H-NMR
(300 MHz, DMSO-d6, δ): 10.82 (s, 1H), 9.41 (s, 1H), 8.57 (s, 1H), 8.01 (d, 1H, J = 7.9 Hz), 7.93-7.84 (m, 3H), 7.71-
7.58 (m, 2H), 7.45 (d, 1H, J = 8.7 Hz), 7.20 (d, 1H, J = 8.5 Hz), 7.15 (s, 1H), 6.97 (d, 1H, J = 8.8 Hz), 6.41 (d, 1H, J =
8.5 Hz), 2.53-2.50 (m, 2H), 2.21 (s, 3H), 1.72 (t, 2H, J = 6.4 Hz), 1.28 (s, 6H). 13C-NMR (75 MHz, DMSO-d6, δ):
164.2, 159.7, 159.5, 156.3, 152.4, 150.6, 134.9, 132.5, 131.1, 129.8, 129.6, 129.5 (2C), 129.2, 127.6 (2C), 126.7, 123.2,
121.8, 121.6, 119.7, 115.7, 113.0, 112.7, 111.1, 108.3, 74.8, 31.7, 26.5 (2C), 21.4, 7.9. MS (ESI+) m/z: 586.1 [M+H]+,
608.1 [M+Na]+, 624.1 [M+K]+. IR (cm-1): 3292, 2971, 1693, 1648, 1589, 1484, 1361, 1322, 1253, 1177, 1154, 1120,
1092, 1074, 1016, 948, 859, 809, 761, 653, 617.
4.1.b.4. 3-(2,2-dimethylchroman-6-carboxamido)-7-hydroxy-8-methyl-2-oxo-2H-chromen-4-yl quinoline-7-sulfonate
(1e)
After purification, 1e was obtained in 52% yield (155 mg, 0.27 mmol). Rf: 0.28 (CH2Cl2/AcOEt: 9/1). m.p.: 293-295
1
°C. H-NMR (300 MHz, DMSO-d6, δ): 10.81 (s, 1H), 9.07 (s, 1H), 9.02 (dd, 1H, J1 = 4.0 Hz, J2 = 1.4 Hz), 8.29-8.23
(m, 2H), 8.08 (d, 1H, J = 8.2 Hz), 7.59-7.47 (m, 3H), 7.03 (dd, 1H, J1 = 8.6 Hz, J2 = 1.8 Hz), 6.98-6.95 (m, 2H), 6.52
(d, 1H, J = 8.5 Hz), 2.63 (t, 2H, J = 6.3 Hz), 2.20 (s, 3H), 1.82 (t, 2H, J = 6.3 Hz), 1.34 (s, 6H). 13C-NMR (75 MHz,
DMSO-d6, δ): 164.0, 159.7, 159.5, 156.4, 153.3, 151.8, 150.7, 142.5, 136.3, 135.6, 132.9, 132.4, 129.2, 128.5, 126.7,
125.1, 123.0, 122.4, 122.0, 119.7, 115.9, 112.9, 112.6, 111.0, 108.6, 74.9, 31.7, 26.5 (2C), 21.6, 7.9. MS (ESI+) m/z:
587.2 [M+H]+, 609.2 [M+Na]+. IR (cm-1): 1606, 1474, 1352, 1259, 1178, 1118, 1091, 995, 842, 735, 691, 604, 584,
552.
9

4.1.c.
6-bromo-3-(2,2-dimethylchroman-6-carboxamido)-7-hydroxy-8-methyl-2-oxo-2H-chromen-4-yl
4-
ACCEPTED MANUSCRIPT
methylbenzenesulfonate (9)
To a round bottom flask charged with 4TCNA (300 mg, 0.55 mmol, 1 eq.) and acetic acid (5 mL), was added dropwise
bromine (31 µL, 0.61 mmol, 1.1 eq) at room temperature. The mixture was stirred at room temperature for 24 hrs, then
hydrolised with a saturated solution of Na2S2O3 and extracted with AcOEt (3 x 20 mL). The combines organic phases
were dried over Na2SO4, filtered and concentrated under reduced pressure. Further purification on silica gel
chromatography delivered compound 9 in 37 % yield (128 mg, 0.20 mmol).
Rf: 0.39 (c-hexane/AcOEt: 6/4). m.p.: 169-171 °C. 1H-NMR (300 MHz, CDCl3, δ): 7.76 (d, 2H, J = 8.2 Hz), 7.60-7.55
(m, 2H), 7.47 (dd, 1H, J = 8.6 Hz, J = 1.9 Hz), 7.22 (s, 1H), 7.20 (d, 2H, J = 8.4 Hz), 6.79 (d, 1H, J = 8.5 Hz), 2.82 (t,
2H, J = 6.6 Hz), 2.34 (s, 3H), 2.32 (s, 3H), 1.85 (t, 2H, J = 6.6 Hz), 1.37 (s, 6H), the -OH proton was not observed. 13C-
NMR (75 MHz, CDCl3, δ): 164.9, 160.1, 158.1, 153.9, 149.4, 148.1, 146.4, 132.9, 130.1 (3C), 128.1 (2C), 127.2,
123.7, 123.6, 121.0, 117.3, 114.4, 113.9, 110.8, 107.2, 75.5, 32.5, 26.9 (2C), 22.3, 21.7, 9.3. MS (APCI+) m/z: 628.0
([M+H]+, 79Br), 630.0 ([M+H]+, 81Br). IR (cm-1): 1733, 1602, 1482, 1365, 1256, 1152, 1119, 1090, 684, 618, 577, 553.
4.4. N-(6-bromo-4,7-dimethoxy-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-dimethylchroman-6-carboxamide (3)
MPHT [35, 36] (i.e. N-methylpyrrolidin-2-one hydrotribromide; 4.4 g, 10.12 mmol, 2 eq) was added portionwise to an
heterogeneous solution of CNBA (2 g, 5.06 mmol, 1 eq) in acetonitrile (80 mL). The reaction mixture was stirred at 80
°C for 14 hrs. The white precipitate formed is then filtered and washed with c-hexane and acetonitrile, dried under high
vacuum to deliver the 6-Br CNBA intermediate in 92% yield (2.2 g, 4.64 mmol).
Rf: 0.19 (c-hexane/AcOEt: 8/2). m.p.: 244-246 °C. 1H-NMR (300 MHz, CDCl3, δ): 14.21 (s, 1H), 8.69 (s, 1H), 8.01 (s,
1H), 7.73-7.65 (m, 2H), 6.87 (d, 1H, J = 8.4 Hz), 5.98 (s, 1H), 2.86 (t, 2H, J = 6.7 Hz), 2.41 (s, 3H), 1.86 (t, 2H, J = 6.7
Hz), 1.37 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 167.1, 161.3, 158.8, 152.8, 152.2, 149.2, 129.7, 127.1, 124.0, 122.2,
121.5, 117.9, 113.1, 111.6, 107.0, 103.4, 75.8, 32.3, 26.9 (2C), 22.3, 9.3. MS (ESI+) m/z: 473.2 ([M+H]+, 79Br), 475.2
([M+H]+, 81Br). IR (cm-1): 3516, 3373, 2924, 1682, 1642, 1608, 1637, 1486, 1341, 1266, 1142, 1114, 1094, 945, 875,
830, 775, 750, 672, 622, 554, 540.
To a solution of 6-Br CNA intermediate (390 mg, 0.82 mmol, 1 eq) and K2CO3 (0.7 g, 4.93 mmol, 6 eq) in dry DMF (5
mL), stirred at room temperature under a nitrogen atmosphere, was added dimethyl sulfate (466 µL, 4.93 mmol, 6 eq).
After 12 hrs the mixture is diluted with AcOEt (20 mL) and the organic phase washed with a saturated solution of
NH4Cl (3 x 15 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. Further purification on silica
gel chromatography delivered compound 3 in 62 % yield (255 mg, 0.51 mmol).
Rf: 0.59 (CH2Cl2/AcOEt : 95/5). m.p.: 232-234 °C. 1H-NMR (300 MHz, CDCl3, δ): 8.04 (s, 1H), 7.94 (s, 1H), 7.68 (d,
1H, J = 2.1 Hz), 7.63 (dd, 1H, J1 = 8.5 Hz, J2 = 2.3 Hz), 6.74 (d, 1H, J = 8.5 Hz), 4.12 (s, 3H), 3.85 (s, 3H), 2.76 (t, 2H,
J = 6.7 Hz), 2.39 (s, 3H), 1.80 (t, 2H, J = 6.7 Hz), 1.34 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 166.9, 162.8, 158.6,
157.9, 157.8, 149.2, 129.6, 127.1, 125.1, 123.8, 121.2, 121.0, 117.4, 115.2, 113.1, 104.7, 75.3, 60.9, 59.4, 32.4, 26.9
(2C), 22.3, 9.7. MS (APCI+) m/z: 502.1 ([M+H]+, 79Br), 504.2 ([M+H]+, 81Br). IR (cm-1): 1714, 1642, 1619, 1490, 1348,
1261, 1179, 1121, 1047, 685.
4.1.d. General procedure for the one-pot Sonogashira coupling/4-MeO deprotection.
A flame-dried resealable Schlenk tube was charged with compound 3 (100 mg, 0.20 mmol, 1 eq), CuI (6 mol %),
PdCl2(PPh3)2 (6 mol %), PPh3 (20 mol %). The Schlenk tube was capped with a rubber septum, evacuated and
backfilled with argon (three times). Triethylamine (0.5 mL) and dry DMF (1.5 mL) were added, followed by a dropwise
10

addition of the terminal alkyne (0.40 mmol, 1.2 eq). The septum was replaced with a Teflon screwcap, the Schlenk tube
ACCEPTED MANUSCRIPT
sealed and the mixture was stirred at 120 °C for 30 minutes. The resulting suspension was cooled to room temperature
and filtred through Celite eluting with ethyl acetate and dichloromethane. The filtrate was then concentrated under
reduced pressure. Purification of the residue by silica gel column chromatography gave the desired product.
4.1.d.1 N-(4-hydroxy-7-methoxy-8-methyl-2-oxo-6-(phenylethynyl)-2H-chromen-3-yl)-2,2-dimethylchroman-6-
carboxamide (4a)
After purification, 4a was obtained in 63% yield (64 mg, 0.13 mmol). Rf: 0.42 (c-hexane/Et2O: 5/5). m.p.: 194-196 °C.
1H-NMR (300 MHz, CDCl3, δ): 14.18 (s, 1H), 8.70 (s, 1H), 8.01 (s, 1H), 7.70-7.66 (m, 2H), 7.57-7.52 (m, 2H), 7.38-
7.33 (m, 3H), 6.86 (d, 1H, J = 8.3 Hz), 4.07 (s, 3H), 2.85 (t, 2H, J = 6.7 Hz), 2.38 (s, 3H), 1.85 (t, 2H, J = 6.7 Hz), 1.37
(s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 167.1, 161.6, 161.3, 158.7, 152.4, 149.4, 131.5 (2C), 129.8, 128.5, 128.4 (2C),
127.1, 126.4, 123.1, 122.3, 121.5, 119.3, 117.9, 113.9, 113.2, 104.0, 93.8, 84.9, 75.8, 61.2, 32.3, 26.9 (2C), 22.3, 9.0.
MS (APCI+) m/z: 510 [M+H]+. IR (cm-1): 1687, 1632, 1490, 1327, 1268, 1111, 727, 614, 584, 575.
4.1.d.2. N-(4-hydroxy-7-methoxy-6-((4-methoxyphenyl)ethynyl)-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-
dimethylchroman-6-carboxamide (4b)
After purification, 4b was obtained in 55 % yield (59 mg, 0.11 mmol). Rf: 0.30 (c-hexane/Et2O: 5/5). m.p.: 167-169 °C.
1H-NMR (300 MHz, CDCl3, δ): 14.09 (s, 1H), 8.62 (s, 1H), 7.92 (s, 1H), 7.66-7.56 (m, 2H), 7.41 (d, 2H, J = 8.5Hz),
6.81 (d, 2H, J = 8.5Hz), 6.80-6.75 (m, 1H), 3.99 (s, 3H), 3.76 (s, 3H), 2.78 (t, 2H, J = 6.6Hz), 2.31 (s, 3H), 1.78 (t, 2H,
J = 6.7Hz), 1.30 (6, 1H). 13C-NMR (75 MHz, CDCl3, δ): 167.0, 161.4, 161.3, 159.8, 158.7, 152.4, 149.1, 132.9 (2C),
129.7, 127.1, 126.1, 122.3, 121.5, 119.2, 117.9, 115.2, 114.2, 114.0 (2C), 113.2, 104.0, 93.9, 83.6, 75.7, 61.1, 55.3,
32.3, 26.9 (2C), 22.3, 9.0. MS (APCI+) m/z: 540.0 [M+H]+. IR (cm-1): 1687, 1632, 1569, 1535, 1512, 1487, 1371, 1317,
1252, 1152, 1114, 1033, 832, 752, 625, 575, 543.
4.1.d.3 N-(4-hydroxy-7-methoxy-8-methyl-2-oxo-6-((3,4,5-trimethoxyphenyl)ethynyl)-2H-chromen-3-yl)-2,2-
dimethylchroman-6-carboxamide (4c)
After purification, 4c was obtained in 33 % yield (79 mg, 0.13 mmol). Rf: 0.42 (Et2O/c-hexane : 5/5). m.p.: 205-207
1
°C. H-NMR (300 MHz, CDCl3, δ): 14.20 (s, 1H), 8.71 (s, 1H), 8.04 (s, 1H), 7.71-7.67 (m, 2H), 6.87 (d, 1H, J = 8.3
Hz), 6.80 (s, 2H), 4.06 (s, 3H), 3.90 (s, 6H), 3.88 (s, 3H), 2.86 (t, 2H, J = 6.6Hz), 2.40 (s, 3H), 1.86 (t, 2H, J = 6.6 Hz),
1.37 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 167.1, 161.5, 161.3, 158.8, 153.2 (2C), 152.3, 149.4, 139.1, 129.8, 127.1,
126.4, 122.2, 121.5, 119.3, 118.1, 117.9, 113.8, 113.3, 108.7 (2C), 104.1, 93.9, 84.0, 75.8, 61.2, 61.0, 56.2 (2C), 32.3,
26.9 (2C), 22.3, 9.0. MS (APCI+) m/z: 600 [M+H]+. IR (cm-1): 1684, 1630, 1536, 1492, 1342, 1237, 1121, 943, 821,
752, 656, 600, 587.
4.1.d.4. N-(4-hydroxy-7-methoxy-8-methyl-2-oxo-6-((trimethylsilyl)ethynyl)-2H-chromen-3-yl)-2,2-dimethylchroman-6-
carboxamide (4d)
After purification, 4d was obtained in 73 % yield (146 mg, 0.29 mmol). Rf: 0.56 (c-hexane/Et2O: 6/4). m.p.: 110-112
1
°C. H-NMR (300 MHz, CDCl3, δ): 14.15 (s, 1H), 8.70 (s, 1H),7.98 (s, 1H), 7.71 (s, 1H), 7.71-7.68 (m, 1H), 6.87 (d,
1H, J = 8.3 Hz), 4.01 (s, 3H), 2.86 (t, 2H, J = 6.7 Hz), 2.36 (s, 3H), 1.86 (t, 2H, J = 6.6 Hz), 1.37 (s, 6H), 0.28 (s, 9H).
13C-NMR (75 MHz, CDCl3, δ): 167.1, 162.0, 161.3, 158.7, 152.3, 149.4, 129.7, 127.1, 127.0, 122.3, 121.5, 119.2,
11

117.9, 113.7, 113.0, 104.0, 100.3, 99.4, 75.8, 60.9, 32.3, 26.9 (2C), 22.3, 8.9, -0.2 (3C). MS (APCI+) m/z: 506.0
ACCEPTED MANUSCRIPT
[M+H]+. IR (cm-1): 1689, 1626, 1489, 1327, 1157, 1120, 998, 838, 649, 567, 550.
4.1.d.5. N-(6-(3-(dimethylamino)prop-1-ynyl)-4-hydroxy-7-methoxy-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-
dimethylchroman-6-carboxamide (4e)
After purification, 4e was obtained in 36 % yield (70 mg, 0.14 mmol). Rf: 0.22 (CH2Cl2/AcOEt : 8/2). m.p.: 141-143
°C. 1H-NMR (300 MHz, CDCl3, δ): 8.69 (s, 1H), 7.94 (s, 1H), 7.70-7.64 (m, 2H), 6.86 (d, 1H, J = 8.3 Hz), 3.97 (s, 3H),
3.58 (s, 2H), 2.85 (t, 2H, J = 6.6 Hz), 2.42 (s, 6H), 2.36 (s, 3H), 1.85 (t, 2H, J = 6.7 Hz), 1.36 (s, 6H), the –OH proton
was not observed. 13C-NMR (75 MHz, CDCl3, δ): 167.1, 161.6, 161.3, 158.8, 152.3, 149.3, 129.7, 127.1, 126.7, 122.3,
121.5, 119.3, 117.9, 113.8, 113.2, 104.0, 88.8, 81.0, 75.7, 61.1, 48.7, 44.1 (2C), 32.3, 26.9 (2C), 22.3, 8.9. MS (APCI+)
m/z: 491 [M+H]+. IR (cm-1): 3325, 2966, 1650, 1600, 1519, 1493, 1402, 1261, 1159, 1019, 948, 801, 660, 568.
4.1.d.6. N-(6-ethynyl-4-hydroxy-7-methoxy-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-dimethylchroman-6-carboxamide
(4f)
An heterogeneous solution of 4d (139 mg, 0.27 mmol, 1 eq) and potassium carbonate (76 mg, 0.54 mmol, 2 eq) in
methanol (10 mL) was stirred at room temperature. After 2 hrs, the mixture was concentrated under reduced pressure.
Purification of the residue by silica gel column chromatography gave the desired product 4f in 93 % yield (111 mg, 0.25
mmol). Rf: 0.25 (c-hexane/Et2O: 6/4). m.p.: 223 -225 °C. 1H-NMR (300 MHz, CDCl3, δ): 14.16 (bs, 1H), 8.68 (s, 1H),
8.00 (s, 1H), 7.74-7.64 (m, 2H), 6.87 (d, 1H, J = 8.3 Hz), 4.00 (s, 3H), 3.31 (s, 1H), 2.86 (t, 2H, J = 6.7 Hz), 2.37 (s,
3H), 1.86 (t, 2H, J = 6.7 Hz), 1.37 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 167.1, 162.1, 161.2, 158.8, 152.2, 149.7,
129.7, 127.3, 127.1, 122.2, 121.5, 119.4, 117.9, 113.2, 112.8, 104.1, 81.7, 79.1, 75.8, 61.2, 32.3, 26.9 (2C), 22.3, 8.9.
MS (APCI-) m/z: 432.0 [M-H]-. IR (cm-1): 3253, 1685, 1626, 1531, 1490, 1315, 1264, 1195, 1156, 1114, 945, 671, 592.
4.1.e. General procedure for the tosylation of 4-hydroxycoumarin derivatives 4a-4f and 6.
To a 10 mL round bottom flask, triethylamine (3 eq.) was added dropwise to a solution of 4-hydroxycoumarin (1 eq.) in
dichloromethane (5 mL), under nitrogen atmosphere. The mixture was stirred for 5 minutes at room temperature,
followed by addition of tosyl chloride (2 eq.). After 12 hrs, the reaction mixture was diluited with EtOAc (10 mL) and
the organic phase washed with a 1N HCl solution (3 x 15 mL), filtered and concentrated under reduced pressure.
Further purification on silica gel chromatography delivered desired 4-tolsyl coumarin derivative.
4.1.e.1. 3-(2,2-dimethylchroman-6-carboxamido)-7-methoxy-8-methyl-2-oxo-6-(phenylethynyl)-2H-chromen-4-yl 4-
methylbenzenesulfonate (5a)
Starting from the 4-hydroxycoumarin 4a (50 mg, 0.1 mmol), after purification, 5a was obtained in 82 % yield (53 mg,
1
0.08 mmol). Rf: 0.10 (CH2Cl2/c-hexane: 9/1). m.p.: 192-194 °C. H-NMR (300 MHz, CDCl3, δ): 7.80 (d, 2H, J = 8.1
Hz), 7.62 (s, 1H), 7.56-7.53 (m, 3H), 7.47-7.44 (m, 2H), 7.39-7.37 (m, 3H), 7.18 (d, 2H, J = 8.2 Hz), 6.79 (d, 1H, J =
8.5 Hz), 4.06 (s, 3H), 2.82 (t, 2H, J = 6.5 Hz), 2.37 (s, 3H), 2.27 (s, 3H), 1.84 (t, 2H, J = 6.6 Hz), 1.37 (s, 6H). 13C-
NMR (75 MHz, CDCl3, δ): 164.1, 161.9, 160.1, 157.9, 149.5, 147.6, 146.2, 133.1, 131.4 (2C), 130.0 (2C), 129.9, 128.6,
128.4 (2C), 128.1 (2C), 127.1, 126.0, 123.8, 122.8, 120.9, 119.8, 117.2, 115.6, 114.1, 113.0, 94.2, 84.4, 75.4, 61.2, 32.5,
26.8 (2C), 22.3, 21.6, 9.0. MS (APCI+) m/z: 664.0 [M+H]+. IR (cm-1): 3310, 1726, 1677, 1607, 1483, 1371, 1255, 1176,
1119, 998, 939, 884, 791, 757, 733, 690, 646.
12

4.1.e.2.
3-(2,2-dimethylchroman-6-carboxamido)-7-methoxy-6-((4-methoxyphenyl)ethynyl)-8-methyl-2-oxo-2H-
ACCEPTED MANUSCRIPT
chromen-4-yl 4-methylbenzenesulfonate (5b)
Starting from the 4-hydroxycoumarin 4b (50 mg, 0.09 mmol), after purification, 5b was obtained in 84 % yield (54 mg,
1
0.08 mmol). Rf: 0.20 (CH2Cl2). m.p.: 187-189 °C. H-NMR (300 MHz, CDCl3, δ): 7.80 (d, 2H, J = 7.8 Hz), 7.60 (s,
1H), 7.55 (s, 1H), 7.49-7.43 (m, 4H), 7.18 (d, 2H, J = 8.1 Hz), 6.91 (d, 2H, J = 8.0 Hz), 6.78 (d, 1H, J = 8.4 Hz), 4.05
(s, 3H), 3.84 (s, 3H), 2.82 (t, 2H, J = 6.2 Hz), 2.36 (s, 3H), 2.27 (s, 3H), 1.84 (t, 2H, J = 6.6 Hz), 1.37 (s, 6H). 13C-NMR
(75 MHz, CDCl3, δ): 164.1, 161.7, 160.1, 159.9, 157.9, 149.3, 147.7, 146.2, 133.1, 132.9 (2C), 129.9 (3C), 128.1 (2C),
127.1, 125.8, 123.9, 120.9, 119.8, 117.2, 115.5, 114.9, 114.5, 114.1 (2C), 113.0, 94.3, 83.1, 75.4, 61.1, 55.3, 32.5, 26.8
(2C), 22.3, 21.6, 9.0. MS (APCI+) m/z: 695.0 [M+H]+. IR (cm-1): 1721, 1606, 1482, 1373, 1248, 1172, 1033, 941, 829,
695.
4.1.e.3. 3-(2,2-dimethylchroman-6-carboxamido)-7-methoxy-8-methyl-2-oxo-6-((3,4,5-trimethoxyphenyl)ethynyl) -2H-
chromen-4-yl 4-methylbenzenesulfonate (5c)
Starting from the 4-hydroxycoumarin 4c (50 mg, 0.08 mmol), after purification, 5c was obtained in 82 % yield (53 mg,
1
0.07 mmol). Rf: 0.48 (CH2Cl2/AcOEt: 95/5). m.p.: 151-153 °C. H-NMR (300 MHz, CDCl3, δ): 7.79 (d, 2H, J = 8.2
Hz), 7.62 (s, 1H), 7.54 (s, 1H), 7.49 (s, 1H), 7.37 (dd, 1H, J1 = 8.6 Hz, J2 = 1.6 Hz), 7.13 (d, 2H, J = 8.1 Hz), 6.80 (s,
2H), 6.76 (d, 1H, J = 8.5 Hz), 4.05 (s, 3H), 3.91 (s, 6H), 3.89 (s, 3H), 2.80 (t, 2H, J = 6.4 Hz), 2.38 (s, 3H), 2.25 (s, 3H),
1.84 (t, 2H, J = 6.6 Hz), 1.36 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 163.9, 161.9, 160.2, 157.9, 153.1 (2C), 149.4,
147.4, 146.0, 139.2, 133.2, 129.9 (3C), 128.0 (2C), 127.0, 126.0, 123.6, 120.8, 119.9, 117.8, 117.1, 115.3, 114.2, 113.3,
108.8 (2C), 94.3, 83.4, 75.4, 61.2, 61.0, 56.2 (2C), 32.4, 26.8 (2C), 22.3, 21.6, 9.0. MS (APCI+) m/z: 754.0 [M+H]+. IR
(cm-1): 2974, 1722, 1604, 1482, 1370, 1240, 1177, 1156, 1119, 1091, 1031, 947, 758, 731, 691.
4.1.e.4.
6-(3-(dimethylamino)prop-1-ynyl)-3-(2,2-dimethylchroman-6-carboxamido)-7-methoxy-8-methyl-2-oxo-2H-
chromen-4-yl 4-methylbenzenesulfonate (5e)
Starting from the 4-hydroxycoumarin 4e (30 mg, 0.06 mmol), after purification, 5e was obtained in 55 % yield (22 mg,
0.03 mmol). Rf: 0.22 (CH2Cl2/MeOH: 9/1). m.p.: 116-118 °C. 1H-NMR (300 MHz, CDCl3, δ): 7.78 (d, 2H, J = 8.2 Hz),
7.57 (s, 1H), 7.52-7.51 (m, 2H), 7.42 (dd, 1H, J1 = 8.6 Hz, J2 = 1.9 Hz), 7.16 (d, 2H, J = 8.2 Hz), 6.78 (d, 1H, J = 8.5
Hz), 3.97 (s, 3H), 3.55 (s, 2H), 2.81 (t, 2H, J = 6.6 Hz), 2.40 (s, 6H), 2.35 (s, 3H), 2.31 (s, 3H), 1.84 (t, 2H, J = 6.6 Hz),
1.37 (s, 6H). 13C-NMR (75 MHz, CDCl3, δ): 164.0, 162.0, 160.1, 157.9, 149.3, 147.4, 146.0, 133.1, 129.9 (3C), 128.0
(2C), 127.1, 126.3, 123.7, 120.8, 119.9, 117.2, 115.4, 114.2, 113.2, 89.1, 80.7, 75.4, 61.2, 48.6, 44.0 (2C), 32.4, 26.8
(2C), 22.3, 21.7, 9.0. MS (APCI+) m/z: 645.0 [M+H]+, 667.0 [M+Na]+. IR (cm-1): 1734, 1603, 1478, 1373, 1260, 1155,
1119, 1009, 946, 757, 729, 682, 629.
4.1.e.5. 3-(2,2-dimethylchroman-6-carboxamido)-6-ethynyl-7-methoxy-8-methyl-2-oxo-2H-chromen-4-yl 4-
methylbenzenesulfonate (5f)
Starting from the 4-hydroxycoumarin 4f (50 mg, 0.11 mmol), after purification, 5f was obtained in 39 % yield (26 mg,
1
0.04 mmol). Rf: 0.50 (CH2Cl2/AcOEt: 95/5). m.p.: 164-166 °C. H-NMR (400 MHz, CDCl3, δ): 7.78 (d, 2H, J = 7.8
Hz), 7.60 (s, 1H), 7.55 (s, 1H), 7.46-7.44 (m, 2H), 7.18 (d, 2H, J = 7.8 Hz), 6.79 (d, 1H, J = 8.4 Hz), 3.99 (s, 3H), 3.29
(s, 1H), 2.82 (t, 2H, J = 6.3 Hz), 2.35 (s, 3H), 2.33 (s, 3H), 1.85 (t, 2H, J = 6.3 Hz), 1.37 (s, 6H). 13C-NMR (100 MHz,
CDCl3, δ): 164.2, 162.5, 160.0, 158.0, 149.8, 147.3, 146.2, 133.0, 130.0 (2C), 129.9, 128.1 (2C), 127.1, 127.0, 123.8,
13

120.9, 120.0, 117.3, 115.7, 113.1 (2C), 82.1, 78.6, 75.4, 61.3, 32.5, 26.9 (2C), 22.3, 21.7, 9.0. MS (APCI+) m/z: 588.0
ACCEPTED MANUSCRIPT
[M+H]+. IR (cm-1): 1730, 1603, 1480, 1365, 1256, 1177, 1118, 997, 937, 756, 692.
4.1.f. N-(4-hydroxy-7-methoxy-6-(4-methoxyphenyl)-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-dimethylchroman-6-
carboxamide (6)
A 10 mL round bottom flask was charged with compound 3 (50 mg, 0.10 mmol, 1 eq.), p-methoxyphenylboronique (23
mg, 0.15 mmol, 1,5 eq.), KF (18 mg, 0.30 mmol, 3 eq.), Pd(OAc)2 (5 mol %) and Xphos (20 mol %). The flask was
evacuated and backfilled with argon (three times). Then dry THF (2 mL) was added and the reaction mixture was
heated to reflux for 24 hrs. The mixture was then filtered through a Celite pad with AcOEt, the solvent evaporated
under reduced pressure and the resulting mixture transferred into a resealable Schlenk tube. Triethylamine (1 mL) and
dry DMF (1 mL) were added, the Schlenk tube sealed and the mixture was stirred at 120 °C for 30 minutes. After
cooling at room temperature the crude mixture was purified on silica gel chromatography delivered product 6 in 63 %
yield (33 mg, 0.06 mmol). Rf: 0.80 (CH2Cl2). MS (APCI+) m/z: 516.0 [M+H]+. Compounds 6 was not enough soluble
for NMR and was used directly in the tosylation step to get compound 7.
4.1.g. 3-(2,2-dimethylchroman-6-carboxamido)-7-methoxy-6-(4-methoxyphenyl)-8-methyl-2-oxo-2H-chromen-4-yl 4-
methylbenzenesulfonate (7)
Product 7 was prepared according to the general procedure for tosylation (4.6.). Starting from the 4-hydroxycoumarin 6
(30 mg, 0.040 mmol), after purification, 7 was obtained in 90 % yield (27 mg, 0.035 mmol).
1
Rf: 0.27 (CH2Cl2). m.p.: 201-203 °C. H-NMR (300 MHz, CDCl3, δ): 7.75 (d, 2H, J = 8.2 Hz), 7.66 (s, 1H), 7.56 (s,
1H), 7.47 (dd, 1H, J1 = 8.6 Hz, J2 = 2.0 Hz), 7.37 (d, 2H, J = 8.7 Hz), 7.09 (d, 2H, J = 8.2 Hz), 6.95 (d, 2H, J = 8.7 Hz),
6.77 (d, 1H, J = 8.6 Hz), 3.86 (s, 3H), 3.40 (s, 3H), 2.80 (t, 2H, J = 6.5 Hz), 2.41 (s, 3H), 2.24 (s, 3H), 1.83 (t, 2H, J =
6.6 Hz), 1.36 (s, 6H), one proton not observed. 13C-NMR (75 MHz, CDCl3, δ): 164.2, 160.5, 159.1 (2C), 157.8, 148.9,
148.5, 145.9, 133.2, 131.8, 130.0 (2C), 129.8 (3C), 129.4, 128.0 (2C), 127.1, 123.9, 123.0, 120.8, 119.9, 117.1, 115.2,
113.8 (2C), 113.0, 75.3, 60.3, 55.2, 32.4, 26.8 (2C), 22.3, 21.5, 9.1. MS (APCI+) m/z: 670.0 [M+H]+. IR (cm-1): 2939,
1734, 1604, 1480, 1370, 1240, 1176, 1155, 1119, 1089, 999, 947, 800, 757, 731, 683.
4.1.h. N-(7-hydroxy-8-methyl-4-(2-morpholinoethylamino)-2-oxo-2H-chromen-3-yl)-2,2-dimethylchroman-6-
carboxamide (8)
A flame-dried resealable Schlenk tube under nitrogen atmosphere, was charged with 4TCNA (100 mg, 0.18 mmol, 1
eq.), 2-morpholinoethanamine (47 mg, 0.36 mmol, 2 eq.) and dioxane (1 mL). The Schlenk tube sealed and the mixture
was stirred at 100 °C for 14 hrs. The resulting suspension was then cooled to room temperature and filtred through
Celite eluting with ethyl acetate and dichloromethane. The filtrate was then concentrated under reduced pressure.
Purification of the residue by silica gel column chromatography gave the desired product 8 in 71 % yield (66 mg, 0.13
mmol).
Rf: 0.20 (CH2Cl2/MeOH: 95/5). m.p.: 186-188 °C. 1H-NMR (300 MHz, DMSO-d6, δ): 10.26 (s, 1H), 9.13 (s, 1H), 7.78
(d, 1H, J = 1.9 Hz), 7.71 (dd, 1H, J1 = 8.5 Hz, J2 = 1.9 Hz), 7.66 (d, 1H, J = 9.0 Hz), 6.84 (d, 1H, J = 9.0 Hz), 6.78 (d,
1H, J = 8.5 Hz), 6.74 (s, 1H), 3.53 (q, 2H, J = 6.1 Hz), 3.43-3.40 (m, 4H), 2.79 (t, 2H, J = 6.6 Hz), 2.50-2.47 (m, 2H),
2.28-2.25 (m, 4H), 2.15 (s, 3H), 1.81 (t, 2H, J = 6.6 Hz), 1.31 (s, 6H). 13C-NMR (75 MHz, DMSO-d6, δ): 166.6, 160.7,
158.0, 156.3, 150.9, 149.4, 129.6, 127.0, 125.4, 120.4, 120.3, 116.2, 111.0, 110.6, 107.4, 93.6, 74.9, 66.0 (2C), 57.1,
14

52.8 (2C), 40.8, 31.8, 26.4 (2C), 21.7, 8.1. MS (APCI+) m/z: 508.0 [M+H]+. IR (cm-1): 1658, 1607, 1548, 1515, 1454,
ACCEPTED MANUSCRIPT
1343, 1263, 1158, 1114, 837, 653.
4.1.i. 3-(2,2-dimethylchroman-6-carboxamido)-7-(2,3,4,6-tetra-O-acétyl-β-glucopyranos-1-yl)-8-methyl-2-oxo-2H-
chromen-4-yl 4-methylbenzenesulfonate (2a)
To a 100 mL round bottom flask, charged with 4TCNA (150 mg, 0.27 mmol, 1 eq.) and dry THF (10 mL) under
nitrogen atmosphere were added a THF (10 mL) solution of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranose (190 mg, 0.54
mmol, 2 eq.) and triphenylphosphine (144 mg, 0.54 mmol, 2 eq.). The reaction mixture was cooled at -78 °C and DIAD
(108 µL, 0.54 mmol, 2 eq.) was added. The reaction was allowed to warm at room temperature. After 24 hrs, the
mixture was diluted with AcOEt (30 mL), the organic phase washed with a NaCl sat. (40 mL), filtered and concentrated
under reduced pressure. Further purification on silica gel chromatography delivered desired product 2a in 20 % yield
(47 mg, 0.05 mmol).
Rf: 0.14 (Et2O/c-hexane: 8/2). m.p.: 143-145 °C. 1H-NMR (400 MHz, CDCl3, δ): 7.76 (d, 2H, J = 8.2 Hz), 7.61 (d, 1H,
J = 8.9 Hz), 7.47 (s, 1H), 7.44 (s, 1H), 7.35 (dd, 1H, J1 = 8.6 Hz, J2 = 1.8 Hz), 7.12 (d, 2H, J = 8.2 Hz), 7.03 (d, 1H, J =
8.9 Hz), 6.76 (d, 1H, J = 8.6 Hz), 5.40-5.29 (m, 2H), 5.19 (t, 1H, J = 9.4 Hz), 5.14 (d, 1H, J = 7.4 Hz), 4.32 (dd, 1H, J1
= 12.2 Hz, J2 = 5.4 Hz), 4.18 (dd, 1H, J1 = 12.2 Hz, J2 = 1.9 Hz), 3.93-3.90 (m, 1H), 2.81 (t, 2H, J = 6.7 Hz), 2.28 (s,
3H), 2.27 (s, 3H), 2.09 (s, 3H), 2.08 (s, 3H), 2.06 (s, 3H), 2.05 (s, 3H), 1.85 (t, 2H, J = 6.7 Hz), 1.37 (s, 6H). 13C-NMR
(100 MHz, CDCl3, δ): 170.5 (C=O, -OAc), 170.1 (C=O, -OAc), 169.3 (C=O, -OAc), 169.1 (C=O, -OAc), 163.9, 160.5,
157.9, 157.5, 149.6, 147.9, 145.9, 133.3, 129.9 (2C), 129.8, 128.0 (2C), 127.1, 123.7, 122.5, 120.8, 117.1, 116.1, 114.4,
113.0, 111.9, 99.0, 75.4, 72.5, 72.3, 70.9, 68.2, 61.8, 32.5, 26.9 (2C), 22.3, 21.6, 20.7, 20.6 (3C), 8.4. MS (APCI+) m/z:
880.2 [M+H]+. IR (cm-1): 2974, 1747, 1609, 1478, 1353, 1218, 1178, 1119, 1036, 947, 906, 811, 761, 736, 691.
4.1.j. N-(4-amino-7-(2,3,4,6-tetra-O-acetyl-β-glucopyranos-1-yl)-8-methyl-2-oxo-2H-chromen-3-yl)-2,2-
dimethylchroman-6-carboxamide (10)
A flame-dried resealable Schlenk tube was charged with 2a (40 mg, 0.04 mmol, 1 eq.) and dry THF (2 mL), under
nitrogen atmosphere. En excess of ammonia (gas) was bubbled into the Schlenk over 15 min, then the Schlenk tube was
sealed and the reaction stirred at room temperature. After 24 hrs, the mixture was filtred through Celite eluting with
ethyl acetate and dichloromethane and the filtrate was concentrated under reduced pressure. Purification of the residue
by silica gel column chromatography gave the desired product 10 in 27 % yield (9 mg, 0.01 mmol). Rf: 0.17 (Et2O/c-
hexane: 8/2). 1H-NMR (300 MHz, CDCl3, δ): 8.06 (s, 1H), 7.69 (m, 2H), 7.40 (d, 1H, J = 8.9 Hz), 6.93 (d, 1H, J = 8.9
Hz), 6.82 (d, 1H, J = 8.3 Hz), 6.02 (bs, 2H), 5.37-5.35 (m, 2H), 5.21-5.15 (m, 2H), 4.30-4.18 (m, 2H), 3.96-3.90 (m,
1H), 2.81 (t, 2H, J = 6.6 Hz), 2.16 (s, 3H), 2.10 (s, 3H), 2.05 (s, 6H), 2.04 (s, 3H), 1.82 (t, 2H, J = 6.6 Hz), 1.35 (s, 6H).
MS (APCI+) m/z: 725.2 [M+H]+.
4.2 Biology
4.2.1. Cell Culture and Drug Treatment. Breast cancer MCF-7 (ER-positive) and MDA-MB-231 (ER-negative) cells
were grown in Dulbecco’s modified eagle medium (DMEM, Lonza, Vervier, Belgium) supplemented with L-glutamine
(2 mM), penicillin (5 IU/mL), streptomycin (50 IU/mL), 10% charcoal-treated fetal calf serum (FCS) (charcoal Norit A
1%, Dextran T70 0.1%, 30 min at room temperature). Multiple myeloma RPMI 8226, LP-1 and prostate PC-3 cancer
cells were grown in RPMI 1640 medium supplemented in L-glutamine (2 mM), penicillin (5 IU/mL), streptomycin (50
IU/mL), 10% heat-inactivated fetal bovine serum (FBS)The monosodium novobiocin salt was obtained from Sigma (St.
Louis, MO) and the proteasome inhibitor MG132 was from Calbiochem (La Jolla, CA). Nvb was diluted in water and
15

coumarin analogues (stock solutions at 10 mM) were diluted in DMSO. Drug treatments of cells were performed during
ACCEPTED MANUSCRIPT
different periods of time in the presence or not of 5 µM of the proteasome inhibitor MG132 (Sigma).
4.2.2. Quantification of Cell Survival/Proliferation. Cells were seeded in 96-well plates at 2500-5000 cells/well, and
after 24 h, serial dilutions of drugs (in complete culture medium) were added. Control condition correspond to the
highest DMSO dilution. After 72 h, for MCF-7 (wild type or resistant) and MDA-MB-231 cells, 3-(4,5-dimethylthiazol-
2-yl)-2,5diphenyltetrazolium bromide (MTT, Sigma) (500
µg/mL) was added to each well during 3 h at 37 °C. Medium
was removed and MTT formazan crystals were dissolved in 100
µL DMSO followed by gentle agitation for 10 min.
The absorbance of converted dye which directly correlates with the number of viable cells was measured at 570 nm
with background substraction at 650 nm using a spectrophotometric microtiter reader (Metertech, Σ960, Fisher-
Bioblock, Illkirch, France). All determinations were carried out in sextuplate, and each experiment was repeated three
times. For myeloma cells and prostate cancer cells, MTS assay was used (CellTiter 96® AQueous One Solution Cell
Proliferation Assay, Promega France, Charbonnières, France). The medium soluble reagent was added after 72h of
treatment in each well. Absorbance was read at 492 nm after 2 or 3 h. All determinations were carried out in triplicate,
and each experiment was repeated at least two times The percentage of survival was calculated as the absorbance ratio
of treated to untreated cells. The IC50 values were determined as the drug concentrations that inhibit cell growth by 50%
compared with growth of vehicle-treated cells.
4.2.3. Cell Extracts and Western Blots. Cells were grown to 50% confluence in 60-mm dishes before exposure to
various agents as indicated in the text and figure legends. Cells were rinsed in PBS, scraped into PBS, collected by
centrifugation, and resuspended in ice-cold lysis buffer (Tris-HCl 50 mM (pH 7.5), NaCl 150 mM, EGTA 1 mM,
glycerol 10% (v/v), Triton X-100 1%, MgCl2 1.5 mM, NaF 10 mM, Na pyrophosphate 10 mM, Na3VO4 1 mM) plus
protease inhibitors (Complete reagent, Roche Diagnostics, Indianapolis, IN) and kept on ice for 15 min with occasional
vortexing. Insoluble debris were removed by centrifugation at 15 000 g for 5 min at 4 °C, and cell lysates were boiled in
Laemmli sample buffer for 3 min. TCEs were obtained from pelleted cells by resuspension in lysis buffer for 30 min at
4 °C and boiling for 5 min in Laemmli sample buffer. Protein concentration was determined by the Bio-Rad Assay.
Equal amounts of protein (20 µg) were fractionated by 8% or 12% SDS-polyacrylamide gel electrophoresis (SDS-
PAGE) and transferred onto Immobilon-P membranes (Millipore, Saint Quentin en Yvelines, France). Membranes were
blocked for 1 h at 37 °C with 10% dry nonfat milk in PBS containing 0.1% Tween 20. ER was detected with the D12
(ER epitope: amino acids 2-185) (Santa Cruz, CA) mouse monoclonal anti-ER antibody used at 1 µg/mL in PBST-2%
milk overnight at 4 °C. The antigen/antibody complexes were detected by incubation with a biotinylated anti-mouse
antibody followed by revelation with the avidin/peroxidase complex (Vectastain ABC Elite Kit, Vector Laboratories,
Inc., Burlingame, CA. Blots were developed using the Immobilon Western Detection Reagent (Millipore). Depending
on the mobility of the proteins, membranes were either stripped (1 h at 50 °C in a medium containing 62.5 mM Tris-
HCl pH 6.8, 2% SDS, and 100 mM 2-mercaptoethanol) or extensively washed before reprobing with different primary
antibodies. Equal protein loading was assessed by examination of the intensities of nonspecific (NS) signals elicited by
the commercial antibodies used and unresponsive to treatments.
4.2.4. Flow Cytometry Cell Cycle Analysis. Cells (1.3 x 105 cells/mL) were cultured in the presence or not of
novobiocin analogues at 100
µM. Nvb at the same concentration served as reference inhibitor. After treatment for 48
and 72 h, cells were washed and fixed in PBS/ethanol (30/70). For cytofluorometric examination, cells (104) were
incubated for 30 min in PBS/Triton X100 0.2% /EDTA 1 mM, and propidium iodide (PI) (50
µg/mL) in PBS
16

supplemented by RNase (0.5 mg/mL). The number of cells in the different phases of the cell cycle was determined, and
ACCEPTED MANUSCRIPT
the percentage of apoptotic cells was quantified. Analyses were performed with a FACS Calibur (Becton Dickinson, Le
Pont de Claix, France). Cell Quest software was used for data acquisition and analysis.
5. Acknowledgments
The CNRS is gratefully acknowledged for financial support of this research. We thank the European Union (EU) within
the EST network BIOMEDCHEM (MEST-CT-2005-020580) for a Ph.D. grant to D. A.
The CNRS (Centre National de la Recherche Scientifique) is gratefully acknowledged for financial support of this
research. We also thank ARC (association pour la recherche sur le cancer), for their financial support of this research.
Our laboratory BioCIS-UMR 8076 is a member of the Laboratory of Excellence LERMIT supported by a grant from
ANR (Agence Nationale de la Recherche, ANR-10-LABX-33). This work on hsp90 inhibition was supported by a
grant from ARC (n° SFI20111203965).
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18

1, 3, 5 and 7A-10CCEPTED MANUSCRIPT
Table 1. Cytotoxic effect of
derivatives against MCF-7 cell line
Compounds
Viab. [%][a]
Compounds
Viab. [%][a]
Compounds
Viab. [%][a]
36
10
96
1a (4TCNA)
2a
5e
61
62
33
22
90
90
89
92
82
89
87
65
1b
1c
1d
3
5f
5a
5b
7
8
1e
5c
9
ND
10
71
Novobiocin
6BrCaQ
10
[a] Value of the anti-proliferative effect (% of viable cells compared to untreated cells 100%) of analogues 1, 3, 5 and 7-10 in MCF-7
cell line at a concentration of 10-4 M (MTT method). ND: Not determined
1

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Table 2. GI50 (µM) values for anti-proliferative effects of
selected compounds 1a, 1d-e and 2a[a] against breast cancer
cell lines (MCF-7)[b]
MCF-7 (µM)
Compound
50
67
64
6
1a (4TCNA)
1d
1e
2a
7
6BrCaQ
260
Novobiocin (Nvb)
[a]
GI50 is the concentration of compound needed to reduce cell
growth by 50% following 72 h cell treatment with the tested drug
(average of three experiments). Values are means of three
experiments, carried out in sextuplate.[b] MCF-7, human breast
cancer cells.
Table 3. Cytotoxicity (GI50 µM, 72 h) a
Compounds
MCF-7
MDA-MB-231c
MCF-7
MCF-7
RPMI 8226
LP-1
PC-3
TamoxifenR
FaslodexR
2a
6
7
10
2
30
25
2.5
5
5
25
10
6BrCaQ
ND
ND
6.2
[a]
GI50 is the concentration of compound needed to reduce cell growth by 50% following 72 h cell treatment with the tested
drug (average of three experiments). Values are means of three experiments, carried out in triplicate or sextuplate. [b] MCF-7:
human breast cancer cells. MCF7 TamoxifenR human breast cancer cells resistant to Tamoxifen. MCF7 FaslodexR: human
breast cancer cells resistant to Foslodex. MDA-MB231: hormone-independent breast cancer. RPMI 8226 and LP-1 : human
myeloma cells. PC-3: human prostate cancer cells. ND. not determined
Table 4. Cell cycle and apoptosis analysis of MCF-7 cells treated with analogue 4TCNA,
6BrCaQ and 2a (100 µM) for 48 h and 72 h.[a]
Sub G1
G0/G1 (%)
S (%)
G2/M (%)
compound
48 h
72 h
48 h
72 h
48 h
72 h
48 h
72 h
DMSO
4TCNA
6BrCaQ
2a
5
6
9.5
87
60.5
37.0
6
20.5
35.5
7
19.0
27.5
41.5
30.5
36.0
47.0
44.0
34.81
25.5
48.0
29.5
40.43
17.14
18.09
13
27
40
30.0
5.5
9.5
55
60.0
[a] Data represent percentage of cells in Sub G1 and G2/M phases of the cell cycle. The results
are the mean of two independent experiments in which no more than 2.5 variations were
measured.
2

Figure 1. Structures of novobiocin, syntAhetCicCdeEriPvaTtiEveDs, 4MTCANNA,U6BSrCCaRQIaPnTd targeted molecules.
Figure 1.
Scheme 1. Synthesis of compounds 1-10.
O
O
O
OH
O
O
O
O
O
S
O
R1
S
O
O
O
R1
Cl
OAc
AcO
AcO
OH
OTs
OH
(a)
(c)
(1.1 equiv)
(b)
NH
O
NH
O
NH
O
NH
O
O
AcO
AcO
AcO
AcO
HO
O
HO
O
O
O
O
O
O
Me
Me
Me
Me
Novobiocin (Nvb)
CNBA
2a
O
AcO
MeO
OH
1a: R1 = tolyl (4TCNA)
1b: R1 = methyl
H2NOCO
OH
1c: R1 = thienyl
1d: R1 = naphtyl
1e: R1 = 7ꢀquinolinyl
(j)
(d)
O
(g)
(i)
N
NH2
O
O
O
O
O
O
O
N
O
O
R1
OH
OMe
NH
NH2
OAc
AcO
AcO
NH
O
Br
NH
O
NH
NH
(e)
O
AcO
MeO
O
MeO
O
3
HO
O
O
8
O
O
O
Me
Me
Me
Me
10
4a: R1 = Ph
4b: R1 = 4(OMe)Ph
4c: R1 = 3,4,5(OMe)Ph
4d: R1 = Me3Si
4e: R1 = (Me)2NCH2
4f: R1 = H
(f)
O
O
(b)
MeO
O
O
OH
OTs
(h)
NH
Br
NH
MeO
O
O
HO
O
O
9
Me
Me
6
O
O
R1
OTs
(b)
NH
O
MeO
O
O
Me
5a: R1 = Ph
5b: R1 = 4(OMe)Ph
MeO
O
OTs
5c: R1 = 3,4,5(OMe)Ph
5e: R1 = (Me)2NCH2
5f: R1 = H
NH
O
MeO
O
Me
7
aReagents and conditions: (a) HCl (12 M), EtOH, reflux, 1 h (b) Pyridine, 0° C to RT, 2.5 h. (c), DIAD (2 equiv), PPh3 (2 equiv), THF, -78 °C to RT,
24 h (d) (i) MPHT (2 equiv), MeCN, 80 °C, 16 h (ii) K2CO3 (6 equiv), Me2SO4 (6 equiv), DMF, RT, 12 h, (e) PdCl2(PPh3)2 (6 mol%), CuI (6 mol%),
alkyne (1 equiv), PPh3 (20 mol%), DMF/Et2NH (1:3), 120 °C, 30 min; (f) (i) Pd(OAc)2 (5 mol%), Xphos (20 mol%), KF (3 equiv), THF, reflux, 24 h
(ii) DMF/Et2NH (1:3), 120 °C, 30 min. (g) Dioxane, sealed tube, 100 °C. (h) K2CO3 (2 equiv), MeOH, RT, 2 h. (i) Br2, AcOH, 24 h, RT. (j) NH3
(gas), THF, RT, 24 h.
1

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A
DMSO
2a
B
4TCNA
DMSO
C
DMSO
1d
1e
MG132
-
+
MG132
-
+
MG132
-
+
-
+
NS
NS
NS
Erα
ERα
Erα
Figure 2 Effects of quinolone analogues 1d, 1e, 2a and 4TCNA on ERα stability. MCF-7 cells were grown and exposed to hsp90 inhibitors (1d, 1e,
2a and 4TCNA, 100 ꢀM) as described in Experimental Section in the presence (+) or absence (−) of the proteasome inhibitor MG132 (5 ꢀM) for 24 h
and cell lysates were analyzed by Western blotting with regard to the levels of ERα. DMSO was used as a control, NS = nonspecific protein band
detected in these conditions and serving as a control of constant protein loading.
2

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Highlights
A new series of novobiocin analogues was designed and synthesized.
Compound 2b showed GI50 values at a micromolar level in various human cancer cells.
2b is a potent inducer of G2/M arrest as well as apoptosis.
2b is able to induce proteasome-mediated degradation of ERα.

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Supporting online material for
Synthesis and Antiproliferative Activity of Novobiocin
Analogues as Potential Hsp90 Inhibitors
Davide Audisio[a], Délphine Methy-Gonnot[b], Christine Radanyi[b], Jack-Michel Renoir[b,c]
,
Stéphanie Denis[b], Félix Sauvage[b], Juliette Vergnaud-Gauduchon[b], Jean-Daniel Brion[a],
Samir Messaoudi* [a], Mouad Alami*[a]
a University Paris-Sud, CNRS, BioCIS-UMR 8076, Laboratoire de Chimie Thérapeutique, Equipe Labellisée Ligue Contre Le Cancer,
LabEx LERMIT, Faculté de Pharmacie, 5 rue J.-B. Clément, Châtenay-Malabry, F-92296, France.
b Institut Galien-Paris Sud, CNRS, UMR 8612, Faculté de Pharmacie, 5 rue J.-B. Clément, Châtenay-Malabry, F-92296, France.
c Present address, INSERM U749, Institut Gustave Roussy, 114 rue Edouard Vaillant, Villejuif, F94805, France.
Corresponding authors. Tel.: +33 1 46 83 58 47. Fax: +33 1 46 83 58 28. Email: samir.messaoudi@u-psud.fr (S.M.) or
mouad.alami@u-psud.fr (M.A.)
In memory of Dr. Christine Radanyi
List of Contents
Copies of 1H and 13C-NMR of compounds described.

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