The concise synthesis of chalcone, indanone and indenone analogues of combretastatin A4

Article abstract of DOI:10.1016/j.bmc.2007.02.006

A series of aryl- and aroyl-substituted chalcone analogues of the tubulin binding agent combretastatin A4 (1) were prepared, using a recently introduced one-pot palladium-mediated hydrostannylation-coupling reaction sequence. These chalcones were converte

Full text of DOI:10.1016/j.bmc.2007.02.006

Bioorganic & Medicinal Chemistry 15 (2007) 3290–3298
The concise synthesis of chalcone, indanone and indenone
analogues of combretastatin A4
Daniel J. Kerr,a Ernest Hamel,b M. Katherine Jungc and Bernard L. Flynna,*
aDepartment of Medicinal Chemistry, Faculty of Pharmacy, Monash University, 381 Royal Pde, Parkville, 3052, Australia
bToxicology and Pharmacology Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis,
National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702, USA
cSAIC-Frederick, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702, USA
Received 2 November 2006; revised 7 February 2007; accepted 8 February 2007
Available online 11 February 2007
Abstract—A series of aryl- and aroyl-substituted chalcone analogues of the tubulin binding agent combretastatin A4 (1) were pre-
pared, using a recently introduced one-pot palladium-mediated hydrostannylation-coupling reaction sequence. These chalcones
were converted to indanones by Nazarov cyclisation, followed by oxidation to give the corresponding indenones. Indenones were
also prepared using a palladium-mediated formal [3+2]-cycloaddition process between ortho-halobenzaldehydes and diarylpropy-
nones. All compounds were assessed as inhibitors of tubulin polymerisation, but only E-31 had activity similar to that of 1. How-
ever, compound E-31 did not exhibit antiproliferative activity against the MCF-7 cell line.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
Combretastatin A4 (CA4) 1 is a cis-stilbene natural
product from the South African tree Combretum
caffrum, originally isolated by Pettit and coworkers
20 years ago (Fig. 1).1 Studies into the anticancer prop-
erties of this compound by Hamel and Pettit revealed
that it binds to the colchicine binding site on the b-tubu-
lin subunit of a,b-tubulin heterodimers.1,2 This binding
inhibits the polymerisation of these heterodimers into
microtubules.2 Interference of tubulin/microtubule poly-
merisation dynamics has two key anticancer effects: (i)
inhibition of cancer cell proliferation through distur-
bance of mitotic spindle function, which leads to cell
apoptosis;3 and (ii) disruption of cell signalling path-
ways involved in regulating and maintaining the cyto-
skeleton of endothelial cells in tumour vasculature,
leading to selective shutdown of blood flow through tu-
mours.4 Due to its poor solubility in aqueous media,
CA4 is administered as a disodium phosphate pro-drug
CA4P 2, which is soluble in saline solutions (for intrave-
nous administration) and that, when cleaved, yields 1
due to the action of non-specific phosphatases.5 Whilst
Figure 1. Combretastatin A4 and selected synthetic analogues.
Keywords: Tubulin polymerisation inhibitor; Chalcone; Indanone;
Indenone.
combretastatin A4 is a powerful antimitotic compound,
its dominant mode of action in tumour growth inhibi-
tion probably results from vasculature shutdown.4 The
*
Corresponding author. Tel.: +61 394792539; fax: +61 399039582;
e-mail: b.flynn@iliad.com.au
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.02.006

D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
3291
Figure 2. New CA4 analogues.
vascular disrupting properties of CA4 and related com-
pounds represent a new approach to cancer therapy.4
CA4 is currently in phase II and III clinical trials based
on the vascular shutdown mechanism of action.6
The poor solubility of CA4 in vehicles suitable for drug
administration, its potential to isomerise to the thermo-
dynamically more stable and essentially inactive
trans-isomer and the desire to find even more potent
and selective compounds have prompted a number of
groups to design more soluble, stable and/or active
analogues. Accordingly, a large number of different
structures containing a trimethoxyphenyl group and a
3-hydroxy-4-methoxyphenyl group in close proximity
to each other (1–3 atom tether) have been prepared
and evaluated as tubulin polymerisation inhibitors.7 Ac-
tive analogues of CA4 that have been prepared include
benzo[b]thiophenes,8 benzo[b]furans,9 indoles9,10 and
chalcones.11 Specific examples include compounds
4–12. Some of these analogues are more potent inhibi-
tors of tubulin polymerisation than CA4 and are
amongst the most potent inhibitors yet reported, partic-
ularly for compounds that bind to the colchicine site
(e.g., compound 8, see Table 1). Furthermore, these ana-
logues do not share the thermodynamic instability of CA4.
A number of compounds encompassed in structures 4–
12 are triaryl analogues of the simple cis-stilbene CA4
and/or analogues that include a carbonyl unit in a
2- or 3-atom tether connecting the aryl groups. In view
of the apparent importance of these additional structur-
al features (carbonyl in the tether and, possibly, the
presence of an additional aryl unit),12 we decided to
investigate the activity of compounds containing three
aryl groups, as represented by chalcone 13 and indanone
and indenone 14 analogues of CA4 (Fig. 2).13,14
2. Synthetic studies
Scheme 1. Reagents: (a) i-PrBr, K2CO3, DMF; (b) Ph3P, CBr4, Zn,
CH2Cl2; (c) n-BuLi (2 equiv), THF then 21 and then protic work-up
and MnO2; (d) n-BuLi (2 equiv), 23, THF; (e) Pd(dba)2, PPh3,
n-Bu3SnH, THF then 22 or 23; (f) same as (e) except use 24 or 25.
Since Cushman et al.15 had shown that the replacement
of the OH group in CA4 with a H group, as in 3, had
little effect on the ability of this class of compound to
inhibit tubulin polymerisation, we did not seek to incor-
porate this group in all our analogues. To prepare a
variety of triaryl chalcone type systems 28–33, we
utilised our recently developed palladium-mediated
hydrostannylation-coupling protocol (Scheme 1).13b
This involved initial conversion of aldehydes 15 and 17
into the gem-dibromostyrenes 18 and 19, respectively.
Conversion of these gem-dibromostyrenes into the
corresponding lithium phenylacetylides provided
efficient access to the 1,3-diarylpropynones 26 and 27.
This was accomplished by treating 18 and 19 with 2 equiv
of n-butyllithium followed by reaction with either 3,4,5-
trimethoxybenzoylchloride or the corresponding benzal-
dehyde and subsequent MnO2 oxidation. Diarylpropy-
nones 26 and 27 were then used as substrates in the
palladium-mediated hydrostannylation-coupling with
benzoylchlorides 22 and 23 to give 2-aroylchalcones (2-
benzylidene-1,3-diarylpropan-1,3-diones) 28–30. Similar

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D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
hydrostannylation-couplings of diarylpropynones 26
and 27 with aryliodides 24 and 25 gave the 2-arylchal-
cones (1,2,3-triarylpropenones) 31–33.
The three steps of (i) coupling of a lithium acetylide
to an acid chloride; (ii) palladium-mediated hydrost-
annylation-coupling and (iii) Nazarov cyclisation
can be achieved as a one-pot procedure, as exempli-
fied in the formation of 44 from 18, 22 and
methylchloroformate.
Although the palladium-mediated hydrostannylation-
coupling protocol typically proceeds through a syn-ad-
dition of the tin-hydride, followed by coupling with
stereochemical retention, all of the products were ob-
tained as mixtures of E,Z-stereoisomers of 28–33. This
isomerism may be promoted by the presence of catalyt-
ic amounts of uncoordinated triphenylphosphine. In
other work, we avoided such isomerism by reducing
the PPh3:Pd ratio, but we did not seek to do this here
as both isomers were desired for testing as inhibitors of
tubulin polymerisation.16 Separation of the E,Z-iso-
meric mixtures of the triarylpropenones 31–33 gave
stable E- and Z-isomers. The determination of E,Z-ste-
reochemistry of triarylpropenones has previously been
based on the infrared absorption of the carbonyl,
where E-isomers are expected to absorb at lower wave-
To access additional indenones of interest we, decided
to employ a procedure first developed by Heck19 and
later generalised by Larock and Cacchi.20 These
groups showed that 2-bromo or 2-iodobenzaldehydes
could be reacted with alkynes in a formal [3+2]-
cycloaddition process under palladium catalysis.18,20
When 2-bromo-5-methoxybenzaldehyde (45) under-
went cycloaddition to 1,3-diarylpropynone 26, a 1:1
mixture of separable regioisomers 46 and 47 was
formed in a moderate yield (45% combined yield).
Similarly, when 2-iodo-5-isopropoxy-4-methoxybenz-
aldehyde (48)21 underwent cycloaddition to 1,3-diaryl-
propynone 27, a 1:1 mixture of separable regioisomers
49 and 50 was formed in low yield (20% combined
yield). Of these two regioisomers, only 50 was depro-
tected to give 51 and a small amount of the mono-
demethylated compound 52. The relative regiochemist-
ry of the indenones was based on the chemical shift of
the carbonyl carbons, with 3-aroyl-2-arylindenones
having carbonyl resonances at around 193 and
196 ppm and 2-aroyl-3-arylindenones having carbonyl
resonances at around 193 and 191 ppm. This pattern
has been seen repeatedly with our other 2-aroyl-3-aryl-
indenones 40–42 and with literature examples of 2-ar-
oyl-3-arylindenones22 (Scheme 2).
numbers (1640–1650 cmÀ1
) than Z-isomers (1650–
1660 cmÀ1).17 All the triarylpropenones 31–33 had
isomers with carbonyl IR absorptions that fell into
either of these two ranges, and their stereochemistry
was assigned on this basis. We also observed that the
chemical shift of the vinylic hydrogen in each Z-isomer
fell 0.2 ppm further downfield than the corresponding
E-isomer, as might be expected for a hydrogen cis to
a carbonyl (Z-isomer) relative to that cis to an aryl
group (E-isomer).18 Further support for these assign-
ments was gained from performing a NOESY 2D
NMR on Z-31, which showed a strong NOE interac-
tion between the vinylic hydrogen and both 4-methoxy-
phenyl groups, which is not possible for an E-isomer.
Additionally, both 4-methoxyphenyl rings exhibited a
strong NOE with the aroyl unit, also impossible for
an E-isomer.18
In the case of the 2-aroylchalcones, E,Z-isomerism is
likely to be spontaneous since the 2-aroylchalcone
Z-28 could not be separated from its stereoisomer
E-28, these isomers existed as a 1:1 equilibrium mix-
ture at ambient temperature. Due to their greater
symmetry, there are no double bond stereoisomers
for 29 and 30.
Nazarov cyclisation of the 2-aryl and 2-aroylchalcones
28–32 was readily achieved using either cupric triflate
or methanesulfonic acid to give indanones 34–38. Simi-
lar results were obtained irrespective of whether a specif-
ic E- or Z-isomer or an isomeric mixture of the
2-arylchalcones was used. All indanones 34–39 were iso-
lated as trans-isomers. In the case of the 2-aroylchalcone
28, where cyclisation could proceed through either one
of two aroyl units, cyclisation is favoured through the
most electron rich aroyl unit to give exclusively 34. Inda-
nones 34 and 36 were readily converted to indenones 40
and 41 through oxidation with 2,3-dichloro-5,6-dicy-
anoquinone (DDQ). In the case of isopropyl protected
system 33, deprotection and Nazarov cyclisation were
achieved in a single step using AlCl3 to give cis-39,
which was oxidised as the crude product to give 43 in
an overall 59% yield.
Scheme 2. Reagents: (a) MeSO3H or CuOTf2, CH2Cl2; (b) AlCl3,
CH2Cl2 (E,Z-33, gives 39); (c) DDQ, CH2Cl2.

D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
3293
3. Biological studies
All chalcones, indanones and indenones prepared above
were evaluated for their capacity to inhibit tubulin poly-
merisation (except for the isopropyl ethers, which were
only tested as the corresponding deprotected phenols).
Those that inhibited the reaction by over 50% at concen-
trations <20 lM (Z-31 and E-31) were also examined
for inhibitory effects on the proliferation of MCF-7
breast cancer cells (Table 1). The newly synthesized
compounds were compared in contemporaneous experi-
ments to the potent tubulin polymerisation inhibitor
combretastatin A4 (1). Of the active compounds, only
triarylpropenone E-31 exhibited activity comparable to
that of CA4 as an inhibitor of tubulin polymerisation.
However, none of the new compounds inhibited growth
of the MCF-7 cells at the highest concentration used
(1 lM), whereas CA4 exhibited a GI50 of 26 nM against
this cancer cell line (Scheme 3).
Figure 3. Summary of tubulin polymerisation inhibitors.
(Fig. 3; Schemes 1 and 4). The benzo[b]furan 8 is one
of the most potent tubulin polymerisation inhibitors
yet reported (entry 7, Table 1), particularly for com-
pounds that interact at the colchicine binding site of
b-tubulin.9a As has been previously shown, when the
oxygen atom X in 8 is replaced with a NH group, as
In combination with our earlier studies,8b,9a this pro-
vides valuable structure–activity relationship (SAR)
information with respect to the role of X in the closely
related triaryl arrangements 6, 8, 10, 47 and E-31
Table 1. The effects of arylchalcones, indanones and indenones on
tubulin polymerisation and MCF-7 cancer cell growth
Compound Inhibition of
tubulin polymerisationa (lM)
Inhibition of
cell growth (lM)
CA4
E-31
Z-31
42
2.0 0.3b
0.026 0.008d
>1.0d
2.5 0.1
6.6 3.0
>1.0d
20
36
>40*,c
1
1
NDe
52
6
NDe
NDe,f
8
10
0.41 0.1c
1.6c
NDe,f
NDe,f
a The tubulin concentration was 10 lM. Inhibition of extent of
assembly was the parameter measured.
b Value same as that obtained in Ref. 9a.
c Value from Ref. 8b, the asterisk indicates that the rate but not the
extent of assembly was inhibited by compound concentrations as
high as 40 mM.
d MCF-7 human breast cancer cells were exposed to a concentration
range of each compound for 48 h. Cell growth was quantitated by
measuring protein with sulforhodamine B. The GI50 value is the
graphically determined compound concentration at which the
increase in cell protein is 50% of the increase in untreated control
cells.27
e ND, not done.
f Against the Burket Lymphoma CA46 cell line the compounds 6, 8
and 10 have been shown to have GI50 values of 0.63, 0.034 and
0.045 lM, respectively.
Scheme 3. Reagents: (a) 18, n-BuLi (2 equiv), THF, then ClC(O)OMe,
then Pd(dba)2, PPh3, n-Bu3SnH and 22, then MeSO3H.
Scheme 4. Reagents: (a) Pd(OAc)2, NaOAc, n-Bu4NCl, DMF; (b)
AlCl3, CH2Cl2.

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D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
in 10 (entry 8, Table 1), some activity is lost.9a In con-
trast, replacing the oxygen atom with a sulfur atom
group, as in 6 (entry 6, Table 1), leads to a much larger
loss of activity. In this work, it has been shown that
when X = C@O, as in 47, all activity is lost.8b When
the X group is removed altogether, as in E-31 and
Z-31 (entries 2 and 3, Table 1), the compound retains
activity as a tubulin polymerisation inhibitor (similar
to CA4), but antiproliferative activity is lost (at least
in the MCF-7 line).
4.2. 3-(3-Isopropoxy-4-methoxyphenyl)-1-(3,4,5-trimeth-
oxyphenyl)prop-2-yn-1-one (27)
n-Butyllithium (9.4 mL, 2.0 M in hexanes, 19 mmol) was
added dropwise to a stirred solution of gem-dibromosty-
rene 1923 (3.29 g, 9.39 mmol) in THF (50 mL) at
À78 ꢁC, and the solution was allowed to warm to
18 ꢁC over 1 h. The solution was recooled to À78 ꢁC,
and 3,4,5-trimethoxybenzoyl chloride 22 was added
(2.27 g, 9.86 mmol, dissolved in 10 mL THF). The solu-
tion was rewarmed to 18 ꢁC, and 100 mL of ethyl ace-
tate was added. After washing with distilled water
(2· 50 mL), the organic phase was dried over MgSO4
and concentrated onto silica gel (10 g) under reduced
pressure. The solid residue was subjected to flash chro-
matography (silica gel, 2% diethyl ether in dichloro-
methane), yielding the product as a white solid (2.27 g,
Compounds such as E-31 that inhibit tubulin polymer-
isation at low concentrations, but that do not exhibit
an antimitotic or cytotoxic effect, may prove useful
as selective vascular disrupting agents. Such agents
interfere with microtubules responsible for regulating
endothelial cell shape and intercellular adhesion.4a In
principle it should be desirable to maximise the differ-
ence between the dose required to affect cell prolifera-
tion and/or viability and the dose required to disrupt
other cellular cytoskeletal functions.23 Further exami-
nation of E-31 and its congeners, in particular more
configurationally stable arrangements, for this role is
ongoing.
1
66%, mp = 130–1 ꢁC). H NMR (300 MHz, CDCl3) d
7.50 (s, 2H), 7.28 (dd, J = 8.3 Hz, 1.8 Hz, 1H), 7.16 (d,
J = 1.8 Hz, 1H), 6.89 (d, J = 8.3 Hz, 1H), 4.54 (septet,
J = 6.1 Hz, 1H), 3.96 (s, 6H), 3.94 (s, 3H), 3.90 (s,
3H), 1.38 (d, J = 6.1 Hz, 6H).13C NMR + APT
(75 MHz, CDCl3) d 176.8 (C), 153.0 (C), 152.9 (C),
147.1 (C), 143.3 (C), 132.3 (C,), 127.3 (CH), 119.3
(CH), 111.7 (C), 111.6 (CH), 106.7 (CH), 94.4 (C),
86.3.4 (C), 71.6 (CH), 61.0 (CH3), 56.2 (CH3), 56.0
(CH3), 21.9 (CH3). IR (KBr disc, cmÀ1): 3011, 2976,
2938, 2838, 2187, 1637, 1586, 1510, 1460, 1413, 1328,
1248, 1127. LRMS (70 eV) m/z (%): 384 (M+Å, 80), 342
(100), 299 (55), 175 (30). HRMS calcd for C22H24O6:
384.1573. Found: 384.1570.
4. Experimental
Melting points were recorded with a Kofler hot-stage
apparatus and are uncorrected. Proton (1H) and car-
bon (13C) NMR spectra were recorded with a Varian
Gemini 300 spectrometer operating at 300 MHz for pro-
ton and 75 MHz for carbon, unless otherwise stated. All
NMR spectra were recorded in (D)chloroform (CDCl3)
at 20 ꢁC. The protonicities of the carbon atoms observed
in the carbon NMR were determined using attached
proton test (APT) experiments. Infrared spectra (IR)
were obtained as KBr discs or as films on NaCl plates
and were recorded on a Perkin-Elmer Spectrum One
Fourier-transform infrared spectrophotometer. Low-
resolution electron impact mass spectra (MS) were
recorded at 70 eV on either a VG micromass 7070F
instrument or a JEOL AX-505H mass spectrometer, un-
less otherwise stated. High-resolution mass spectra
(HRMS) were recorded on a VG micromass 7070F
instrument. Tetrahydrofuran (THF) was distilled under
nitrogen from sodium benzophenone ketyl. Dichloro-
methane was distilled from calcium hydride. All experi-
ments were performed under an anhydrous atmosphere
of N2 (g) except as indicated. Flash chromatography
was performed on Merck Kieselgel 60.
4.3. (E,Z)-2-(4-Methoxybenzylidine)-3-(4-methoxyphe-
nyl)-1-(3,4,5-trimethoxyphenyl)-1,3-propadione (E,Z-28)
Pd(dba)2 (32 mg, 0.06 mmol) was added to a solution of
PPh3 (60 mg, 0.24 mmol) in THF (14 mL) and stirred
for 0.25 h at 18 ꢁC. After this time, 26 (560 mg,
1.72 mmol) was added and the reaction mixture cooled
to 0 ꢁC. Bu3SnH (0.48 mL, 1.72 mmol) was then added
dropwise and the mixture allowed to warm to room tem-
perature over 1 h. 4-Methoxybenzoyl chloride 22
(352 mg, 2.06 mmol) and CuCl (150 mg, 1.5 mmol) were
then added and the reaction mixture stirred at 18 ꢁC for
16 h. Then KF(aq) (30%, 20 mL) was added and the reac-
tion mixture stirred for 2 h. The triphasic (organic,
aqueous and solid) mixture was filtered through Celite
and the retained solid washed with ethyl acetate
(25 mL). The aqueous and organic phases were separat-
ed and the latter dried over MgSO4 and concentrated
onto silica gel (2 g) under reduced pressure. The solid
residue was subjected to flash chromatography (silica
gel, hexanes/dichloromethane/diethyl ether 1:1:0.27) giv-
ing the product as a light yellow solid (667 mg, 84%,
mp = 107–110 ꢁC). 1H NMR analysis indicated that this
material, E,Z-28, exists as an equilibrium mixture of
double bond stereoisomers. 1H NMR (300 MHz,
CDCl3) d Isomer A: 7.95 (d, J = 8.8 Hz, 2 H), 7.56 (s,
1H), 7.32 (d, J = 8.8 Hz, 2H), 7.08 (s, 2H), 6.87 (d,
J = 8.8 Hz, 2H), 6.75 (d, J = 8.8 Hz, 2H), 3.89 (s, 3H),
3.82 (s, 9H), 3.75 (s, 3H). Isomer B: 7.88 (d,
J = 8.7 Hz, 2H), 7.45 (s, 1H), 7.27 (d, J = 8.7 Hz, 2H),
7.25 (s, 2H), 6.95 (d, J = 8.7 Hz, 2H), 6.78
4.1. 3-(4-Methoxyphenyl)-1-(3,4,5-trimethoxyphenyl)prop-
2-yn-1-one (26)
This material was prepared in three steps from anisalde-
hyde 15 by converting it first to gem-dibromostyrene 18,
which was converted to the corresponding lithium acet-
ylide and reacted with 3,4,5-trimethoxybenzaldehyde.
The resulting alcohol was oxidised with MnO2.24 1H
NMR (300 MHz, CDCl3) d 7.60 (d, J = 8.3 Hz, 2H),
7.48 (s, 2H), 6.92 (d, J = 8.3 Hz, 2H), 3.95 (s, 6H),
3.93 (s, 3H), 3.84 (s, 3H).

D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
3295
(d, J = 8.7 Hz, 2H), 3.87 (s, 3H), 3.86 (s, 3H), 3.80 (s,
6H), 3.76 (s, 3H). 13C NMR + APT (75 MHz, CDCl3)
d 196.0 (C), 195.9 (C), 193.4 (C), 193.3 (C), 164.1 (C),
163.2 (C), 161.3 (C), 161.2 (C), 153.1 (C), 152.8 (C),
143.0 (CH), 142.5 (CH), 141.6 (C), 137.24 (C), 137.17
(C), 132.8 (C), 132.2 (CH), 131.9 (CH), 131.85 (CH),
131.81 (CH), 131.5 (C), 130.0 (C), 129.6 (C), 125.72
(C), 125.68 (C), 114.2 (CH), 114.0 (CH), 113.7 (CH),
106.8 (CH), 106.6 (CH), 60.8 (CH3), 56.12 (CH3),
56.06 (CH3), 55.4 (CH3), 55.2 (CH3). IR (KBr disc,
cmÀ1): 3072, 3004, 2936, 2838, 1656, 1642, 1599, 1582,
1507, 1460, 1414, 1331, 1258, 1167, 1Å123, 1025, 848,
831. LRMS (70 eV) m/z (%): 462 (M+ , 50), 327 (25),
195 (45), 135 (100). HRMS calcd for C27H26 O7:
462.1679. Found: 462.1677.
2838, 1647, 1602, 1579, 1507, 1468, 1414, 1330, 1256,
1156, 1124, 1031, 1006,Å 920, 833, 810, 765. LRMS
(70 eV) m/z (%): 434 (M+ , 100), 287 (85), 239 (55), 195
(90). HRMS calcd for C26H26O6: 434.1729, Found:
434.1734.
4.5. ( )-4,5,6-Trimethoxy-2-(4-methoxybenzoyl)-3-(4-meth-
oxyphenyl)indan-1-one (34)
Methanesulfonic acid (30 lL, 0.44 mmol) was added to
a solution of E,Z-28 (185 mg, 0.40 mmol) in dry dichlo-
romethane (5 mL). After stirring for 20 min, the solution
was diluted with diethyl ether (20 mL), washed with dis-
tilled water (20 mL), dried over MgSO4 and concentrat-
ed under reduced pressure to yield 34 as a light brown
1
solid (161 mg, 87%, mp = 131–3 ꢁC). H NMR analysis
4.4. (E and Z)-2,3-Bis-(4-methoxyphenyl)-1-(3,4,5-tri-
methoxyphenyl)prop-2-en-1-one (E-31 and Z-31)
indicated that the product 34 exists as an equilibrium
mixture of an enol tautomer and the trans-keto tauto-
1
mer. H NMR (300 MHz, CDCl3) d trans-Keto tauto-
Pd(dba)2 (27 mg, 0.05 mmol) was added to a solution of
PPh3 (50 mg, 0.20 mmol) in THF (7 mL) and stirred for
0.25 h at 18 ꢁC. After this time, 26 (326 mg, 1.00 mmol)
was added and the reaction mixture cooled to 0 ꢁC.
Bu3SnH (0.28 mL, 1.00 mmol) was then added dropwise
and the mixture warmed to room temperature over 1 h.
4-Iodoanisole 24 (281 mg, 1.20 mmol) and CuCl
(200 mg, 2.0 mmol) were then added and the reaction
mixture stirred at 18 ꢁC for 72 h. Then KF(aq) (30%,
20 mL) was added and the reaction mixture stirred for
2 h. The triphasic (organic, aqueous and solid) mixture
was filtered through Celite, and the retained solid was
washed with ethyl acetate (25 mL). The aqueous and
organic phases were separated and the latter dried over
MgSO4 and concentrated onto silica gel (1 g) under re-
duced pressure. The solid residue was subjected to flash
chromatography (silica gel, hexanes/dichloromethane/
diethyl ether 1:1:0.1/1:1:0.15) giving the product as two
separable tan solids (combined mass 404 mg, 93%).
Higher Rf isomer Z-31, (160 mg, 37%, mp = 136–7 ꢁC).
1H NMR (300 MHz, CDCl3) d 7.35 (d, J = 8.9 Hz,
2H), 7.28 (s, 2H), 7.21 (d, J = 8.8 Hz, 2H), 7.05 (s,
1H), 6.87 (d, J = 8.8 Hz, 2H), 6.73 (d, J = 8.9 Hz, 2H),
3.87 (s, 3H), 3.80 (s, 3H), 3.79 (s, 6H), 3.74 (s, 3H).
13C NMR + APT (75 MHz, CDCl3) d 198.7 (C), 159.4
(C), 159.2 (C), 153.0 (C), 142.7 (C), 138.1 (C), 131.4
(C), 131.1 (C), 130.0 (CH), 128.4 (C), 128.1 (CH),
127.4 (CH), 114.2 (CH), 113.9 (CH), 106.9 (CH), 60.9
(CH3), 56.1 (CH3), 55.3 (CH3), 55.2 (CH3). IR (KBr
disc, cmÀ1): 3003, 2940, 2836, 1654, 1606, 1578, 1512,
1501, 1462, 1412, 1325, 1246, 1176, 1158, 1123, 1028,
999, 852, 763, 564. LRMS (70 eV) m/z (%): 424 (M+Å,
100), 287 (70), 239 (35), 195 (100). HRMS calcd for
C26H26O6: 434.1729. Found: 434.1731. Lower Rf Isomer
(E-31), (244 mg, 56%, mp = 112–4 ꢁC) 1H NMR
(300 MHz, CDCl3) d 7.23 (s, 1H), 7.20 (d, J = 8.7 Hz,
2H), 7.10 (d, J = 8.9 Hz, 2H), 7.05 (s, 2H), 6.90 (d,
J = 8.7 Hz, 2H), 6.73 (d, J = 8.9 Hz, 2H), 3.90 (s, 3H),
3.83 (s, 3H), 3.82 (s, 6H), 3.78 (s, 3H). 13C NMR + APT
(75 MHz, CDCl3) d 196.5 (C), 160.0 (C), 159.1 (C),
152.6 (C), 141.2 (C), 139.3 (CH), 138.2 (C), 133.3 (C),
132.0 (CH), 130.9 (CH), 129.3 (C), 127.5 (C), 114.3
(CH), 113.7 (CH), 107.2 (CH), 60.9 (CH3), 56.1 (CH3),
55.2 (CH3). IR (KBr disc, cmÀ1): 3003, 2968, 2941,
mer: 8.00 (d, J = 8.9 Hz, 2H), 7.03 (d, J = 8.7 Hz, 2H),
7.03 (s, 1H), 6.94 (d, J = 8.9 Hz, 2H), 6.82 (d,
J = 8.7 Hz, 2H), 5.10 (d, J = 2.4 Hz, 1H), 4.61 (d,
J = 2.4 Hz, 1H), 3.92 (s, 3H), 3.89 (s, 3H), 3.87 (s,
3H), 3.77 (s, 3H), 3.45 (s, 3H). Enol tautomer: 7.68 (d,
J = 8.9 Hz, 2H), 7.20 (s, 1H), 6.99 (d, J = 8.7 Hz, 2H),
6.81 (d, J = 8.9 Hz, 2H), 6.63 (d, J = 8.7 Hz, 2H), 5.23
(s, 1H), 3.93 (s, 3H), 3.88 (s, 3H), 3.80 (s, 3H), 3.68 (s,
3H), 3.28 (s, 3H). 13C NMR + APT (75 MHz, CDCl3)
d 199.2 (C), 195.8 (C), 192.2 (C), 170.7 (C), 163.9 (C),
161.7 (C), 158.5 (C), 157.9 (C), 155.0 (C), 154.6 (C),
150.1 (C), 149.7 (C), 149.2 (C), 147.5 (C), 144.3 (C),
140.1 (C), 135.2 (C), 132.8 (C), 132.2 (CH), 132.0 (C),
130.5 (C), 130.4 (CH), 129.2 (CH), 129.1 (C), 128.5
(CH), 126.2 (C), 115.2 (C), 114.0 (CH), 113.7 (CH),
113.33 (CH), 113.27 (CH), 100.8 (CH), 100.6 (CH),
67.1 (CH), 60.9 (CH3), 60.8 (CH3), 60.14 (CH3), 60.08
(CH3), 56.2 (CH3, 2C), 55.5 (CH3), 55.3 (CH3), 55.2
(CH3), 55.0 (CH3), 45.6 (CH), 45.2 (CH). IR (KBr disc,
cmÀ1): 2942, 2837, 1708, 1664, 1602, 1512, 1466, 1421,
1343, 1315, 1265, 1175, 1123, 1092, 1031, 835, 821,
792, 570. LRMS (70 eV) m/z (%): 462 (M+Å, 35), 327
(95), 135 (100). HRMS calcd for C27H26O7: 462.1679.
Found: 462.1676.
4.6. ( )-trans-4,5,6-Trimethoxy-2,3-bis(4-methoxyphenyl)-
indan-1-one (37)
Cupric triflate (78 mg, 0.216 mmol) was added to a solu-
tion of E,Z-31 (78 mg, 0.180 mmol) in dry dichloro-
methane (2 mL). After stirring for 4 h, the solution
was concentrated directly onto silica gel (0.5 g). Flash
chromatography (silica gel, hexanes/dichloromethane/
diethyl ether 1:1:0.1/1:1:0.15) yielded 37 as a tan solid
(74 mg, 94%, mp = 128 ꢁC), as well as oxidised material
1
(3 mg, 3%) and impure cis-isomer (2 mg, 2%). H NMR
(300 MHz, CDCl3) d 7.15 (s, 1H), 7.01 (d, J = 8.7 Hz,
4H), 6.84 (d, J = 8.7 Hz, 2H), 6.83 (d, J = 8.7 Hz, 2H),
4.48 (d, J = 3.2 Hz, 1H), 3.94 (s, 3H), 3.93 (s, 3H),
3.78 (s, 3H), 3.77 (s, 3H), 3.66 (d, J = 3.2 Hz, 1H),
3.38 (s, 3H). 13C NMR + APT (75 MHz, CDCl3) d
205.0 (C), 158.6 (C), 158.3 (C), 155.0 (C), 150.2 (C),
149.0 (C), 143.2 (C), 135.7 (C), 131.5 (C), 131.3 (C),
128.8 (CH), 128.2 (CH), 114.2 (CH), 113.9 (CH), 100.8

3296
D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
(CH), 64.0 (CH), 60.8 (CH3), 60.0 (CH3), 56.2 (CH3),
55.1 (CH3), 51.6 (CH). IR (KBr disc, cmÀ1): 3084,
3067, 3037, 3011, 2938, 2836, 1709, 1612, 1599, 1584,
1512, 1466, 1417, 1344, 1306, 1249, 1175, 1127, 1102,
1028, 974, 835, 801. LRMS (70 eV) m/z (%): 434 (M+Å,
100), 135 (20), 91 (25). HRMS calcd for C26H26O6:
434.1729. Found: 434.1732.
55.9 (CH3), 55.7 (CH3). IR (KBr disc, cmÀ1): 3369,
3080, 2925, 2853, 1697, 1607, 1581, 1501, 1467, 1412,
1351, 1296, 1123, 1023. LRMS (70 eV) m/z (%): 508
(M+Å, 100), 493 (35). HRMS calcd for C28H28O9:
508.1733. Found: 508.1727.
4.9. ( )-(trans)-Methyl-4,5,6-trimethoxy-3-(4-methoxy-
phenyl)indan-1-one-2-carboxylate (44)
4.7. 4,5,6-Trimethoxy-2-(4-methoxybenzoyl)-3-(4-meth-
oxyphenyl)-1H-inden-1-one (40)
n-Butyllithium (1.2 mL, 1.7 M in hexanes, 2.0 mmol)
was added dropwise to a stirred solution of gem-dib-
romostyrene 18 (292 mg, 1.00 mmol) in THF (7 mL)
at À78 ꢁC. The solution was warmed to 18 ꢁC over
1 h. The solution was recooled to À78 ꢁC, and methyl
chloroformate (84 lL, 1.05 mmol) was added. The
solution was rewarmed to 18 ꢁC and PPh3 (50 mg,
0.20 mmol) and Pd(dba)2 (27 mg, 0.05 mmol) were
added. This solution was stirred for 0.5 h. Bu3SnH
(0.29 mL, 1.04 mmol) was added dropwise, followed
0.5 h later by 3,4,5-trimethoxybenzoyl chloride 23
(282 mg, 1.2 mmol) and CuCl (100 mg, 1.0 mmol).
After stirring for 24 h, the solvent was removed under
the flow of a stream of nitrogen, followed by evacua-
tion. The residue was dissolved in dichloromethane
(7 mL), and methanesulfonic acid (325 lL, 5.0 mmol)
was added. After 0.5 h, KF (30% w/v in H2O,
15 mL) was added, and the triphasic mixture was stir-
red for 12 h. To this mixture, H2O (50 mL) and
diethyl ether (50 mL) were added and the phases sep-
arated. The aqueous phase was re-extracted with ether
(2· 30 mL), and the combined organic fractions were
dried over MgSO4 and concentrated onto silica gel
(2 g) under reduced pressure. The solid residue was
subjected to flash chromatography (silica gel, hex-
anes/dichloromethane/diethyl ether 20:20:3), and 44
Indanone 34 (62 mg, 0.132 mmol) and 2,3-dichloro-5,6-
dicyanoquinone (45 mg, 0.198 mmol) were dissolved in
dry 1,2-dichloroethane (2 mL) and stirred at reflux for
7 days. After this time, the solution was decanted from
the precipitate (dihydro-DDQ), concentrated onto sil-
ica gel (0.5 g) and flash chromatographed (silica gel,
5:5:1, hexanes/dichloromethane/diethyl ether) to yield
40 as a red/orange solid (50 mg, 82%, mp = 164–
5 ꢁC). 1H NMR (300 MHz, CDCl3)
d 7.76 (d,
J = 8.9 Hz, 2H), 7.47 (d, J = 8.9 Hz, 2H), 7.08 (s,
1H), 6.78 (d, J = 8.9 Hz, 4H), 3.93 (s, 3H), 3.91 (s,
3H), 3.80 (s, 3H), 3.77 (s, 3H), 3.41 (s, 3H). 13C
NMR + APT (75 MHz, CDCl3) d 192.4 (C), 190.9
(C), 163.6 (C), 162.1 (C), 160.9 (C), 155.4 (C), 150.3
(C), 147.3 (C), 131.9 (C), 131.7 (CH), 130.1 (CH),
130.0 (C), 127.2 (C), 126.4 (C), 124.8 (C), 113.4
(CH), 112.9 (CH), 104.8 (CH), 61.3 (CH3), 61.1
(CH3), 56.4 (CH3), 55.3 (CH3), 55.1 (CH3). IR (KBr
disc, cmÀ1): 3073, 3010, 2962, 2843, 1694, 1648, 1594,
1503, 1468, 1407, 1362, 1310, 1243, 1169, 1122, 1045,
1024, 837. LRMS (70 eV) m/z (%): 460 (M+Å, 100),
445 (15), 432 (20), 353 (20), 327 (15), 135 (35), 105
(30). HRMS calcd for C27H24O7: 460.1522. Found:
460.1511.
1
was obtained as a light brown oil (155 mg, 40%). H
4.8. 3-(3-Hydroxy-4-methoxyphenyl)-4,5,6-trimethoxy-2-
(3,4,5-trimethoxyphenyl)-1H-inden-1-one (43)
NMR (300 MHz, CDCl3) d 7.08 (s, 1H), 7.03 (d,
J = 8.7 Hz, 2H), 6.82 (d, J = 8.7 Hz, 2H), 4.91 (d,
J = 3.2 Hz, 1H), 3.91 (s, 6H), 3.80 (s, 3H), 3.78 (s,
3H), 3.61 (d, J = 3.2 Hz, 1H), 3.38 (s, 3H). 13C
NMR + APT (75 MHz, CDCl3) d 197.8 (C), 168.7
(C), 158.4 (C), 155.0 (C), 150.1 (C), 149.3 (C), 143.5
(C), 134.5 (C), 130.2 (C), 128.2 (CH), 113.9 (CH),
100.8 (CH), 63.6 (CH), 60.7 (CH3), 59.9 (CH3), 56.1
(CH3), 55.0 (CH3), 52.7 (CH3), 45.3 (CH). IR (neat,
cmÀ1): 2998, 2949, 2838, 1738, 1709, 1600, 1512,
1471, 1313, 1248, 1126, 1032, 837. LRMS (70 eV) m/
z (%): 386 (M+Å, 85), 354 (40), 326 (100), 297 (15).
HRMS calcd for C21H22O7: 386.1366. Found:
386.1362.
AlCl3 (41 mg, 0.304 mmol) was added to a stirred solu-
tion of propenone E,Z-33 (42 mg, 0.076 mmol) in dry
dichloromethane (2 mL). After 30 min, the reaction
was quenched with aqueous ammonium chloride (10%,
10 mL). This mixture was extracted with diethyl ether
(3 · 10 mL) and the combined organic fractions dried
over MgSO4 and concentrated under reduced pressure.
This crude material was dissolved in dry dichlorometh-
ane, and 2,3-dichloro-5,6-dicyanoquinone (18 mg,
0.080 mmol) was added. This solution was then refluxed
for 2 days. After this time, the solution was decanted
from the precipitate (dihydro-DDQ), concentrated onto
silica gel (0.5 g) and flash chromatographed (silica gel,
7% diethyl ether in dichloromethane) to yield 43 as a
4.10. 6-Methoxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxy-
benzoyl)-1H-inden-1-one (46) and 6-methoxy-2-(4-meth-
oxyphenyl)-3-(3,4,5-trimethoxybenzoyl)-1H-inden-1-one
(47)
1
dark red solid (23 mg, 59%, mp = 175–8 ꢁC). H NMR
(300 MHz, CDCl3) d 7.05 (s, 1H), 7.02 (d, J = 1.9 Hz,
1H), 6.82–6.86 (m, 2H), 6.46 (s, 2H), 5.65 (s, 1H), 3.91
(s, 3H), 3.91 (s, 3H), 3.87 (s, 3H,), 3.81 (s, 3H), 3.64
(s, 6H), 3.41 (s, 3H). 13C NMR + APT (75 MHz,
CDCl3) d 195.7 (C), 156.0 (C), 154.2 (C), 152.5 (C),
149.3 (C), 147.5 (C), 146.7 (C), 145.1 (C), 137.2 (C),
131.4 (C), 128.7 (C), 127.8 (C), 126.7 (C), 126.4 (C),
120.6 (CH), 114.8 (CH), 110.0 (CH), 107.0 (CH), 104.6
(CH), 61.3 (CH3), 61.1 (CH3), 60.8 (CH3), 56.5 (CH3),
Palladium(II) acetate (12 mg, 0.05 mmol), sodium ace-
tate (164 mg, 2.00 mmol), tetrabutylammonium chloride
(150 mg, 0.540 mmol), 2-bromo-5-methoxybenzalde-
hyde 45(108 mg, 0.500 mmol) and propynone 26
(326 mg, 1.00 mmol) were added to degassed N,N-
dimethylformamide (10 mL). This mixture was heated
at 100 ꢁC until disappearance of the aldehyde, which

D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
3297
was confirmed by TLC. The mixture was then taken up
References and notes
in diethyl ether (50 mL) and washed with aqueous
ammonium chloride (10%, 3· 30 mL), followed by dis-
tilled water (30 mL). The organic phase was dried over
MgSO4 and evaporated under reduced pressure onto
silica gel (0.5 g). Two isomers were isolated in similar
yields after flash chromatography (silica gel, 1:1:0.075/
1:1:0.18 hexanes/dichloromethane/diethyl ether). Lower
1. Pettit, G. R.; Singh, S. B.; Hamel, E.; Lin, C. M.; Alberts,
D. S.; Garcia-Kendall, D. Experientia 1989, 45, 209.
2. (a) Lin, C. M.; Singh, S. B.; Chu, P. S.; Dempcy, R. O.;
Schmidt, J. M.; Pettit, G. R.; Hamel, E. Mol. Pharmacol.
1988, 34, 200; (b) Lin, C. M.; Ho, H. H.; Pettit, G. R.;
Hamel, E. Biochemistry 1989, 28, 6984.
3. For a review see Jordan, M. A.; Wilson, L. Nat. Rev.
Cancer 2004, 4, 253.
1
Rfisomer (46), 52 mg, 23%, mp = 143–5 ꢁC; H NMR
(300 MHz, CDCl3) d 7.44 (d, J = 8.8 Hz, 2H), 7.30 (d,
J = 8.2 Hz, 1H), 7.19 (d, J = 2.5 Hz, 1H), 7.06 (s, 2H),
6.87 (dd, J = 8.2, 2.5 Hz, 1H), 6.86 (d, J = 8.8 Hz, 2H),
3.86 (s, 3H), 3.84 (s, 3H), 3.79 (s, 3H), 3.76 (s, 6H). 13C
NMR + APT (75 MHz, CDCl3) d 192.9 (C), 191.2 (C),
162.21 (C), 162.16 (C), 161.7 (C), 152.7 (C), 142.6
(C), 134.5 (C), 133.5 (C), 131.9 (C), 130.1 (CH), 129.4
(C), 124.3 (CH), 124.0 (C), 116.5 (CH), 114.2 (CH),
110.7 (CH), 106.9 (CH), 60.8 (CH3), 56.1 (CH3), 55.8
(CH3), 55.3 (CH3). IR (KBr disc, cmÀ1): 3064, 2997,
2938, 2838, 1707, 1629, 1604, 1581, 1508, 1447, 1415,
1349, 1255, 1123, 1020, 839, 797. LRMS (70 eV) m/z
(%): 460 (M+Å, 100), 417 (35), 293 (45), 195 (30). HRMS
calcd for C27H24O7: 460.1522. Found: 460.1523. Higher
4. For reviews, see: (a) Tozer, G. M.; Kanthou, C.;
Baguley, B. C. Nat. Rev. Cancer 2005, 5, 423; (b)
Griggs, J.; Metcalfe, J. C.; Hesketh, R. The Lancet
Oncol. 2001, 2, 82.
5. Pettit, G. R.; Temple, C., Jr.; Narayanan, V. L.; Varma,
R.; Simpson, M. J.; Boyd, M. R.; Rener, G. A.; Bansal, N.
Anti-Cancer Drug Des. 1995, 10, 299.
6. As reported at http://www.oxigene.com, June 2006.
7. For reviews, see: (a) Hsieh, H. P.; Liou, J. P.; Mahindroo,
N. Curr. Pharm. Des. 2005, 11, 1655; (b) Cirla, A.; Mann,
J. Nat. Prod. Rep. 2003, 20, 558; (c) Li, Q.; Sham, H. L.
Expert Opin. Ther. Patents 2002, 12, 1663; (d) Marx, M.
A. Expert Opin. Ther. Patents 2002, 12, 769; (e) Tron, G.
C.; Pirali, T.; Sorba, G.; Pagliai, F.; Busacca, S.; Genaz-
zani, A. A. J. Med. Chem. 2006, 49, 3033.
8. (a) Pinney, K. G.; Bounds, A. D.; Dingeman, K. M.;
Mocharla, V. P.; Pettit, G. R.; Bai, R.; Hamel, E. Bioorg.
Med. Chem. Lett. 1999, 9, 1081–1086; (b) Flynn, B. L.;
Verdier-Pinard, P.; Hamel, E. Org. Lett. 2001, 3, 651.
9. (a) Flynn, B. L.; Hamel, E.; Jung, M. K. J. Med. Chem.
2002, 45, 2670; (b) Pinney, K. G.; Pettit, G. R.; Mocharla,
V. P.; Del Pilar Majia, M.; Shirali, A. PCT Int. Appl. WO
9839323, 1998. Chem. Abstr. 1998, 129, 245037.
10. (a) Medarde, M.; Ramos, A. C.; Caballero, E.; Pelaez-
Lamamie de Clairac, R.; Lopez, J. L.; Gravalos, D. G.;
San Feliciano, A. Bioorg. Med. Chem. Lett. 1999, 9, 2303;
(b) Gastpar, R.; Goldbrunner, M.; Marko, D.; Von
Angerer, E. J. Med. Chem. 1998, 41, 4965; (c) Liou, J.-
P.; Chang, Y.-L.; Kuo, F.-M.; Chang, C.-W.; Tseng, H.-
Y.; Wang, C.-C.; Yang, Y.-N.; Chang, J.-Y.; Lee, S.-J.;
Hsieh, H.-P. J. Med. Chem. 2004, 47, 4247; (d) De
Martino, G.; Edler, M. C.; Regina, G. L.; Coluccia, A.;
Barbera, M. C.; Barrow, D.; Nicholson, R. I.; Chiosis, G.;
Brancale, A.; Hamel, E.; Artico, M.; Silvestri, R. J. Med.
Chem. 2006, 49, 947.
1
Rf isomer (47), 50 mg, 22%, mp = 104–5 ꢁC; H NMR
(300 MHz, CDCl3) d 7.34 (d, J = 8.7 Hz, 2H), 7.18 (s,
2H), 7.16 (d, J = 2.3 Hz, 1H), 6.94 (d, J = 8.1 Hz, 1H),
6.78 (dd, J = 8.1, 2.3 Hz, 1H), 6.75 (d, J = 8.7 Hz, 2H),
3.86 (s, 3H), 3.82 (s, 3H), 3.74 (s, 9H). 13C NMR + APT
(75 MHz, CDCl3) d 196.4 (C), 193.3 (C), 160.9 (C), 159.9
(C), 153.0 (C), 149.0 (C), 143.5 (C), 136.0 (C), 133.0
(C), 131.5 (C), 130.5 (CH), 129.8 (C), 122.5 (C), 122.4
(CH), 117.2 (CH), 113.9 (CH), 111.4 (CH), 106.6 (CH),
60.9 (CH3), 56.1 (CH3), 55.7 (CH3), 55.1 (CH3). IR
(KBr disc, cmÀ1): 3098, 2994, 2938, 2831, 1712, 1637,
1607, 1578, 1509, 1470, 1413, 1349, 1312, 1250, 1126,
1027, 835, 794, 768. LRMS (70 eV) m/z (%): 460 (M+Å,
100), 195 (25). HRMS calcd for C27H24O7: 460.1522.
Found: 460.1519.
4.11. Biological materials and methods
Bovine brain tubulin was prepared as described previ-
ously,25 and MCF-7 human breast cancer cells were pro-
vided by the Screening Technologies Branch, National
Cancer Institute. The tubulin assembly procedure26
and techniques used to culture the MCF-7 cells and
quantitate their growth27 have been described in detail
elsewhere.
11. (a) Ducki, S.; Mackenzie, G.; Lawrence, N. J.; Snyder, J.
P. J. Med. Chem. 2005, 48, 457; (b) Ducki, S.; Forrest, R.;
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C.; Zaharevitz, D. W.; Day, B. W.; Wipf, P.; Hamel, E.;
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13. (a) Certain aspects of this work are the subject of a
recently filed patent application and a communication:
Flynn, B. L., Hamel, E. PCT application WO 02/060872
A1, published August 2002; (b) Kerr, D. J.; Metje, C.;
Flynn, B. L. Chem. Commun. 2003, 1308.
14. Subsequent to our initial reports in this area (see Ref. 13)
others have reported on the synthesis of diarylchalcones
and indanones and their activity as tubulin polymerisation
inhibitors Lawrence, N. J.; Armitage, E. S. M.; Greedy,
B.; Cook, D.; Ducki, S.; McGown, A. T. Tetrahedron Lett.
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15. Cushman, M.; Nagarathnam, D.; Gopal, D.; Chakraborti,
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16. Jackson, K., Flynn, B. L. unpublished results, presumably
uncoordinated Ph3P can induce cis-trans isomerism of the
enone.
Acknowledgment
This work was supported in part by National Cancer
Institution Contract Number NO-CO-12400.
Supplementary data
Preparative procedures and spectral data for com-
pounds 29, 30, 32, 35, 36, 38, 41, 42, 50, 51 and 52.
NOESY NMR for compound Z-31. Supplementary
data associated with this article can be found, in the on-
line version, at doi:10.1016/j.bmc.2007.02.006.

3298
D. J. Kerr et al. / Bioorg. Med. Chem. 15 (2007) 3290–3298
17. Mittal, S.; Durani, S.; Kapil, R. J. Med. Chem. 1985, 28,
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18. See Supplementary data.
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23. Hessian, K. O.; Flynn, B. L. Org. Lett. 2003, 5, 4377.
24. Banwell, M. G.; Flynn, B. L.; Hockless, D. C. R. Chem.
Commun. 1997, 23, 2259; Riddley, C. P.; Reddy, M. V. R.;
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20. Larock, R. C.; Doty, M. J.; Cacchi, S. J. Org. Chem. 1993,
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21. Ramkumar, D.; Kalpana, M.; Varghese, B.; Sankarar-
aman, S. J. Org. Chem. 1996, 61, 2247.
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27. Verdier-Pinard, P.; Lai, J.-Y.; Yoo, H.-D.; Yu, J.; Mar-
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