Synthesis and evaluation of double bond substituted combretastatins

Article abstract of DOI:10.1016/j.ejmech.2004.12.008

A series of combretastatins substituted with epoxides, amides and small alkyl groups has been synthesised and evaluated for cytotoxicity and their ability to inhibit the assembly of tubulin. The methyl and ethyl substituted phenols 36, 44 have shown potent antimitotic effects whilst exhibiting reduced cytotoxicity.

Full text of DOI:10.1016/j.ejmech.2004.12.008

European Journal of Medicinal Chemistry 40 (2005) 529–541
www.elsevier.com/locate/ejmech
Original article
Synthesis and evaluation of double bond substituted combretastatins
John A. Hadfield a,b,*, Keira Gaukroger b, Nicholas Hirst a, Anna P. Weston a,
Nicholas J. Lawrence c,d, Alan T. McGown a,b
a Centre for Molecular Drug Design, Cockcroft Building, University of Salford, Manchester M5 4WT, UK
b Drug Development Section, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Wilmslow Road, Manchester M20 4BX, UK
c Department of Chemistry, UMIST, P.O. Box 88, Manchester M60 1QD, UK
d Department of Chemistry, Cardiff University, P.O. Box 912, Cardiff CF10 3TB, UK
Received 28 August 2004; revised and accepted 21 December 2004
Available online 09 March 2005
Dedicated to Professor David Crout to mark the occasion of his retirement
Abstract
A series of combretastatins substituted with epoxides, amides and small alkyl groups has been synthesised and evaluated for cytotoxicity
and their ability to inhibit the assembly of tubulin. The methyl and ethyl substituted phenols 36, 44 have shown potent antimitotic effects
whilst exhibiting reduced cytotoxicity.
© 2005 Elsevier SAS. All rights reserved.
Keywords: Combretastatin; Tubulin; Antimitotic
1. Introduction
The combretastatins are a group of compounds isolated
[1–3] from the bark and stemwood of the South African tree
Combretum caffrum. Combretastatin A-4 (1) (Fig. 1) is the
most potent antimitotic agent isolated from C. caffrum and
interacts with the colchicine site on tubulin [2].Also combre-
tastatin A-4 (1) has the ability to damage tumour vasculature
Fig. 1
cle (2).
. Structures of antimitotic agents combretastatin A-4 (1) and heterocy-
at 10% of its maximum tolerated dose whilst leaving normal
vasculature intact [4].
The structural features of the combretastatins, which are
thought to play an important role in their antimitotic activi-
ties, have previously been published [5–7]. These features
include: a cis double bond, a trimethoxylated A ring, a small
substituent on the B ring 4-position. Recently it has been
shown [8] that a trimethylated A ring combretastatin is less
cytotoxic to K562 human leukaemia cells but a more potent
antimitotic agent than combretastatin A-4. This suggests that
a trimethoxy unit is not essential for antimitotic activity.
Several combretastatins (e.g. 2) (Fig. 1) which have the
olefinic bond incorporated into a heterocyclic ring have shown
[9] potent antimitotic properties. This suggested that modifi-
cation of the double bond could produce effective antimitotic
agents. The chalcones are another group [3,10–13] of antimi-
totic agents, which are similar in structure to the combretast-
atins and also possess a double bond. With the chalcones their
biological activities are enhanced when the double bond is
substituted with a small alkyl group. Having noted this, our
group has synthesised several combretastatin derivatives
which have the double bond possessing substituents or incor-
porated into a ring system. The syntheses and biological activi-
ties of these compounds are described herein.
* Corresponding author. Tel.: +44 161 295 4030; fax: +44 161 295 5111.
E-mail address: j.a.hadfield@salford.ac.uk (J.A. Hadfield).
0223-5234/$ - see front matter © 2005 Elsevier SAS. All rights reserved.
doi:10.1016/j.ejmech.2004.12.008

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J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
2. Chemistry
We first explored replacing the double bond with an
epoxide ring. A previous attempt [14] by Pettit et al. at the
formation of an oxirane using Jacobsen oxidation from
TBDMS protected combretastatin A-4 resulted in the forma-
tion of the diaryl ketone 4 (Scheme 1). Cope et al. have
described [15] the epoxidation of both cis and trans stilbene
using peracetic acid and sodium acetate. However, our
attempts to oxidise combretastatins using this method yielded
only starting materials.
Scheme 3. Synthesis of oxiranes (8, 9). Reagents and conditions (i) NaH,
3,4,5-trimethoxybenzaldehyde; (ii) benzyltriethylammonium chloride, tetra-
hydrothiophene, 4-ethylbenzaldehyde, Rh2(OAc)2.
As an alternative strategy we next attempted to create the
desired epoxide bond at the same time as forming the two-
carbon bridge between the two aryl rings. Aggarwal et al.
have investigated [16–19] the enantioselective synthesis of
epoxides using the reaction of enantiopure sulphur ylides with
aldehydes and ketones. As the potential bioactivities of cis or
trans epoxidised combretastatins were unknown, we used tet-
rahydrothiophene as the ylide in an attempt to isolate both
isomers (each in racemic form) for testing. The tosyl hydra-
zone salt 6 was synthesised (Scheme 2) and reacted with 3,4,5-
trimethoxybenzaldehyde. However, only the hydrazone 5 pre-
cursor could be isolated from this reaction. Using a one-pot
procedure 3,4,5-trimethoxybenzaldehyde and 4-toluene-
sulfonylhydrazide 7 were treated with sodium hydride fol-
lowed by rhodium(II) acetate dimer, tetrahydrothiophene, ben-
zyltriethylammonium chloride and 4-ethylbenzaldehyde. This
reaction afforded, after chromatography, the cis epoxide 8 in
moderate yield along with a small amount of the trans iso-
mer 9 (Scheme 3). The stereochemistry of the isomers could
be determined using NMR spectroscopy. The epoxide ring
protons for the cis isomer 8 appear ca. 1 ppm downfield from
those of the trans compound 9. The assignment is supported
by the Karplus equation which predicts that the cis epoxide
8, in which the protons have a dihedral angle of ca. 0°, would
have a greater coupling constant than the trans isomer 9 where
the dihedral angle is 120°. In the NMR spectra, these protons
in the cis 8 and trans 9 isomers showed coupling constants of
4.5 and 1.9 Hz respectively.
Replacing 4-ethylbenzaldehyde with isovanillin in the
above procedure failed to yield any epoxides. However, when
the reaction was carried out using silyl-protected isovanillin
10 [20] the trans epoxide 11 alone was isolated. Desilylation
using fluoride (Scheme 4) gave the required epoxide 12. The
stereochemistry of these epoxides was again elucidated using
NMR spectroscopy. The epoxide ring protons showed a cou-
pling constant of 1.9 Hz in both cases.
Colchicine is an antimitotic agent [3,10], which is water
soluble owing to its amide group. This led us to synthesise a
series of combretastatins with amide substituents on the
double bond. Reaction of 4-methoxyphenylacetic acid with
3,4,5-trimethoxybenzaldehyde under Perkin conditions
afforded [6] the propenoic acid 13. Esterification to 14 fol-
lowed by reduction using lithium aluminium hydride afforded
alcohol 15 in good yield. Treatment of this alcohol 15 under
Mitsunobu conditions gave phthalimide 16 which then yielded
methylamine 17 after treatment with hydrazine. The desired
combretastatins 18–25 with amide groups on the side of the
double bond distal to the trimethoxy aryl ring were synthe-
sised by treating amine 17 with either an acid chloride or
with a carboxylic acid in the presence of 1-hydroxy-
benzotriazole (HOBt) and 1-(3-dimethylaminopropyl)-3-
ethylcarbodiimide (EDC) (Scheme 5). Similarly, starting from
the known [21] amine 26, a series of combretastatins 27–32
with the amide group on the side of the double bond proxi-
mal to the trimethoxy aryl ring were prepared (Scheme 6).
As mentioned earlier, the chalcones which have an -alkyl
group attached to the double bond show greater antimotic
activities than those which are unsubstituted. This led us to
synthesise a series of stilbenes where the side of the olefinic
Scheme 1. Formation of the phenstatin (4) from stilbene (3).
Scheme 4. Synthesis of oxiranes (11) and (12). Reagents and conditions: (i)
NaH; (ii) tetrahydrothiophene, 3,4,5-trimethoxybenzaldehyde, benzyltriethy-
lammonium chloride, Rh2(OAc)2, (iii) tetrabutylammonium fluoride.
Scheme 2
NaOMe.
.
Preparation of sodium salt (6). Reagents and conditions (i)

J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
531
Scheme 5
. Synthesis of amides (18–25). Reagents and conditions: (i) MeOH/H2SO4; (ii) LiAlH4; (iii) diisopropyl azodicarboxylate, phthalimide, Ph3P; (iv)
N2H2; (v) RCOCl/pyridine or RCOOH/EDC/HOBt/N-ethyldiisopropylamine.
Scheme 7. Attempted preparation of stilbenes (35, 36). Reagents and condi-
tions: (i) EtPPh3Br, KN(Me3Si)2.
rable mixture of the desired Z- and E-stilbenes 35, 39. Silyl
group deprotection using fluoride provided the desired phe-
nols 36, 40. Similarly the reaction of acetophenone 41 with
phosphonium bromide 37 yielded a mixture of the desired Z-
and E-ethyl substituted stilbenes 42, 43.Again treatment with
fluoride yielded the free phenols 44, 45 (Scheme 8). Wittig
chemistry was also successful in the synthesis of the
tetramethoxy stilbenes 47, 48 from the reaction of 4-methoxy-
benzyltriphenylphosphonium bromide 46 and acetophenone
38 (Scheme 9).
The stereochemistry of these methyl and ethyl substituted
stilbenes was elucidated using UV and NMR spectroscopy.
Stilbenes with the aryl rings cis to each other have extinction
coefficients in their UV spectra of lower magnitude (ca.
10,000–20,000) compared to their trans isomers and have
maximum absorptions at 20–30 nm lower than their trans
counterparts. For these stilbenes all the designated stere-
ochemistries are in agreement with the above criteria. Also
Scheme
6. Reagents and conditions: (i) RCOCl/pyridine or
RCOOH/EDC/HOBt/N-ethyldiisopropylamine.
bond proximal to the trimethoxy group was substituted with
a small alkyl group (Scheme 7).
The first attempt to synthesise a combretastatin with a
methyl group on the olefinic bond utilised Heck chemistry.
Treatment of aldehyde 10 with ethyltriphenylphosphonium
bromide afforded an inseparable isomeric mixture of predomi-
nantly cis alkene 33 cis/trans (15:1). Treatment of this alkene
mixture 33 with 3,4,5-trimethoxyiodobenzene under Heck
conditions using triphenylphosphine and palladium(II) acetate
failed to produce the desired stilbene 35. Using the free phe-
nol 34 in place of 33 also failed to give stilbene 36 under
these conditions. However, reaction of phosphonium bro-
mide 37 with acetophenone 38 successfully provided a sepa-

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J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
Scheme 8. Synthesis of stilbenes (35, 36, 39–45). Reagents and conditions: (i) n-BuLi, (ii) Bu4NF.
the E isomers the CH2 protons form crosspeaks with both the
2′, 6′ aromatic protons of ring A and the 2″, 6″ aromatic pro-
tons of ring B. For the E compounds no crosspeaks are seen
for the olefinic proton. These spectra again confirm the ste-
reochemistry of these stilbenes (Fig. 3).
3. Biological results and discussion
Scheme 9. Synthesis of stilbenes (47, 48). Reagents and conditions: (i)
n-BuLi.
The stilbenes were tested for cytotoxicity against the
human leukaemia K562 cell line and for their ability to inhibit
the assembly of tubulin and to displace colchicine from its
binding site on tubulin. For the epoxides the biochemical data
is shown in Table 1.Although the stilbene equivalent of ethyl-
substituted epoxides shows good cytotoxicity and the ability
to inhibit the assembly of tubulin, these epoxides 8, 9 are
non-cytotoxic and do not interact with tubulin. However, it is
noteworthy that the cis epoxide 8 is ca. 20 times more cyto-
toxic than the trans equivalent 9. The trans epoxide 11 of
combretastatin A-4 shows good cytotoxicity in K562 cells
(IC50 = 90 nM). Although epoxides in general are poor drugs
this suggests that the cis isomer of 11 may be a good target
for SAR studies. However, this agent 11 (trans) was ineffec-
tive in the tubulin assays.
the signals corresponding to the methyl group (or CH2 pro-
tons of the ethyl group) and the olefinic proton in the E iso-
1
mers appear downfield to those in the Z equivalents. In H
NOESY spectra (spectra not shown) of the Z isomers the CH3
protons of the methyl group and CH2 protons of the ethyl
group form crosspeaks with both the olefinic proton and 2′,
6′ aromatic protons on the A ring (Fig. 2). In the spectra of
The data for the amines (17, 26) and amides (18–25, 27–32)
is depicted in Table 2. For these amides only the chloroethyl
21, chlorobenzyl 30 and trifluoroethyl 25 compounds showed
less than µM IC50s. The amine 26 showed the most potent
cytotoxicity (0.23 µM) of these compounds. This is a 200-
fold less potent than combretastatinA-4 (1).Also these agents
were not able to inhibit the assembly of tubulin (data not
shown).
Fig. 2. Idealised conformers of the Z isomer to illustrate the formation of
NOESY crosspeaks between the CH2 protons, and both the olefinic proton,
shown underlined, and aromatic protons, 2′ and 6′, (2′ shown in italics).
Fig. 3
. Idealised conformers of the E isomer to illustrate the formation of NOESY crosspeaks between the CH2 protons, and both the aromatic protons (under-
lined), 2′ and 6′ on the A ring, and the aromatic protons on the B ring, 2″ and 6″, 2″ shown in italics.

J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
533
Table 1
on the double bond showed more potent abilities in inhibit-
ing the assembly of tubulin than combretastatinA-4 (1). More-
over, both the agents 36, 44 were 40 and 120 times less cyto-
toxic (IC50s 40 and 120 nM respectively) than combretastatin
A-4 (1) (IC50 = 1 nM).
Compound
IC50 (K562)
0.001
0.54
IC50 MA
0.175
>10
IC50 CD
3
1
8
9
11
>25
>25
>25
10
>10
0.09
>10
Cells treated with antimitotic agents accumulate their DNA
in the G2/M phase of the cell cycle and several of the above
tubulin active agents were subjected to cell cycle analysis.
These results are depicted in Table 4. Of the epoxides only
the cis ethyl-substituted stilbene 8 showed potent ability to
cause cells to accumulate in the G2/M phase. This perhaps
indicates the requirement for the two aryl rings to be cis. The
three tubulin active alkyl substituted stilbenes 36, 44, 47 also
showed potent ability to cause cells to accumulate in the G2/M
phase.
Table 2
Compound
IC50 (K562)
2.95
0.23
2.3
17
26
18
19
20
21
22
23
24
25
27
28
29
30
31
32
3.3
27.0
0.6
0.7
22.4
20.6
0.6
4. Conclusions
11.3
1.5
Stilbenes possessing heterocyclic rings on the double bond
(e.g. 2) have previously shown potent antimitotic effects. The
simple epoxides 8, 9 showed only moderate cytotoxicity to
K562 cells, but failed to interact with tubulin (Table 1). The
trans isomer 9 of the epoxide of combretastatin A-4 (1) did
show potent cytotoxicity (IC50 = 90 nM) although this agent
also failed to inhibit the assembly of tubulin.
Of the amides the choroethyl and trifluoroethyl agents 21,
25 showed the best cytotoxicities (IC50 = 600 nM) (Table 2).
However, these agents did not inhibit the assembly of tubu-
lin.
The phenolic Z-stilbenes 36, 44 and the tetramethoxystil-
bene 47 possessing alkyl groups on the double bond all
showed potent ability to block cells in the G2/M phase of the
cell cycle. The phenolic stilbenes 36, 44 were more potent
(ca. 25%) in inhibiting the assembly of tubulin than combre-
tastatin A-4 (1). However, these agents 36, 44 were consider-
ably less cytotoxic to K562 cells than combretastatin A-4 (1)
(40- and 120-fold, respectively).
All the data here are consistent with the known pharma-
cophore [5–8] for the combretastatins [(Z) double bond, small
group on the 4-position of ring B, trimethoxy/trimethyl sub-
stitution on ring A]. What is particularly significant is the
potent ability of phenols 36, 44 to inhibit the assembly of
tubulin whilst showing considerably less cytotoxicity in com-
parison with combretastatin A-4. This may suggest that an
agent able to cause vascular damage (via microtubule disrup-
tion) may be designed to possess minimal cytotoxicity. The
4.8
1.0
3.1
4.5
The biochemical data for the agents with methyl or ethyl
groups 35, 36, 39–48 on the double bond is shown in Table 3.
As expected all the Z-stilbenes 35, 36, 42, 44, 47 showed
greater potencies in the cytotoxicity assay and the tubulin
assay than their E-counterparts 39, 40, 43, 45, 48. The tet-
ramethoxycombretastatin 47 possessing a methyl group on
the double bond (but without a hydroxy group on the B ring)
showed some cytotoxicity (IC50 = 100 nM) and moderate abil-
ity to inhibit the assembly of tubulin. More significantly the
phenolic compounds 36, 44 with both methyl and ethyl groups
Table 3
Compound
IC50 (K562)
IC50 MA
0.175
1.5
IC50 CD
3
1
0.001
0.2
6
35
39
36
40
42
43
44
45
46
47
>25
>25
6
>10
0.04
0.7
0.5
3.4
0.12
4
0.13
>10
>25
>25
>25
>25
>25
>25
>25
>10
>10
0.13
>10
0.1
0.8
1.3
>10
Table 4
Compound
% of cells with DNA content <2n
% of cells with DNA content ≥ 2n
% of cells in G0–G1 phase
% of cells in S phase
% of cells in G2–M phase
8
9
11
36
44
47
16
27
3
4
20
40
55
22
19
22
76
50
27
73
74
73
10
19
5
23
24
23
7
5

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J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
antivascular activity of 36 and 44 is currently being assessed
and these results will be reported in due course.
ride (557 mg, 2.25 mmol), tetrahydrothiophene (198 mg,
198 µl, 2.25 mmol) and 4-ethylbenzaldehyde (1.64 g, 1.67 ml,
12.2 mmol) were added sequentially. The reaction mixture
was stirred vigorously at 40 °C for 6 h and quenched by the
addition of water (20 ml) and EtOAc (20 ml). The organic
layer was separated and the aqueous layer was extracted with
EtOAc (2 × 20 ml), the combined organic phases dried
(MgSO4) and concentrated in vacuo. Flash column chroma-
tography (petroleum ether/EtOAc 9:1) afforded trans epoxide
9 as a clear oil (1.10 g, 29%). Rf 0.24 (petroleum ether/EtOAc
3:1). dH (300 MHz) 1.27 (3 H, t, J = 7.5, CH3), 2.68 (2 H, q,
J = 7.5, CH2), 3.81 (1 H, d, J = 1.9, CH), 3.85 (1 H, d, J = 1.9,
CH), 3.87 (3 H, s, OCH3), 3.89 [6 H, s, (CH3)2], 6.59 (2 H, s,
H-2′,6′), 7.14 (2 H, d, J = 8.3, H-3″,5″), 7.19 (2 H, d, J = 8.3,
H-2″,6″). dC (100 MHz) 16.1 (CH3), 29.1 (CH2), 56.5 (CH3),
61.3 (CH3), 63.2 (CH), 63.4 (CH), 102.4 (CH), 126.0 (CH),
128.6 (CH), 133.4 (C), 134.6 (C), 138.3 (C), 145.1 (C), 154.0
(C). m/z (FAB) 315 [(MH)+, 100%]. (Found: M+ 314.1512;
C, 72.7; H, 7.0%. C19H22O4 requires M+ 314.1518; C, 72.7;
H, 7.05%). Further elution afforded cis isomer 8 as a white
solid (94 mg, 2%). M.p. 54–56 °C. Rf 0.19 (petroleum
ether/EtOAc 3:1). dH (300 MHz) 1.18 (3 H, t, J = 7.5, CH3),
2.59 (2 H, q, J = 7.5, CH2), 3.71 [6 H, s, (CH3)2], 3.78 (3 H,
s, OCH3), 4.26 (1 H, d, J = 4.5, CH), 4.35 (1 H, d, J = 4.5,
CH), 6.37 (2 H, s, H-2′,6′), 7.07 (2 H, d, J = 8.3, H-3″,5″),
7.15 (2 H, d, J = 8.3, H-2″,6″). dC (100 MHz) 16.0 (CH3),
28.9 (CH2), 56.4 (CH3), 60.1 (CH3), 60.5 (CH), 61.2 (CH),
104.5 (CH), 127.4 (CH), 127.8 (CH), 130.5 (C), 132.0 (C),
137.6 (C), 144.1 (C), 153.1 (C). m/z (FAB) 315 [(MH)+, 45%],
135 (100%). (Found: M+ 314.1516; C, 72.7; H, 7.2. C19H22O4
requires M+ 314.1518; C, 72.7; H, 7.05%).
5. Experimental protocols
5.1. Chemistry
General: All reagents and chromatography grade solvents
were obtained from commercial sources and used without
further purification unless indicated. Flash column chroma-
tography was performed on silica gel [Fluka Silica gel 60
220–440 mesh (35–70 µm)] and TLC was carried out using
silica (0.2 mm, 60 F254) pre-coated, aluminium backed plates.
Mass spectra were recorded onVG70-70 Eq. (FAB, CI+, EI+)
and MS50 (FAB) spectrometers, with only major peaks being
reported. Melting points (m.p.) were determined on a Gallen-
kamp m.p. apparatus and are uncorrected. The UV/VIS spec-
tra were determined using a Hewlett–Packard HP8452 diode-
array spectrophotometer. Elemental analyses were carried out
by the Microanalytical Department at UMIST and Manches-
ter University and are within 0.3% of theoretical values. GC
was carried out using a Perkin–Elmer 8500 Gas Chromato-
graph analyser with a CW20 M column, 25 m × 0.31 mm
(film thickness 0.17 µM). 1H NMR spectra were recorded at
300 MHz on a Bruker AC-300 instrument or at 400 MHz on
a Bruker AC-400 MHz instrument. 13C NMR spectra were
recorded at either 75.5 MHz on a Bruker AC-300 instrument
or at 100 MHz on a Bruker AC-400 instrument. Chemical
shifts (d) are quoted in ppm, relative to TMS and are refer-
enced to the CDCl3 unless otherwise stated. Coupling con-
stants (J) are reported to 1 decimal place. For 1,4-disubstituted
compounds, only JA–B is given.
5.1.3. Trans-2-(3′,4′,5′-Trimethoxyphenyl)-3-(3″-t-
butyldimethylsilyloxy-4″-methoxy-phenyl)oxirane (11)
Oxirane 11 was prepared from 3,4,5-trimethoxybenzal-
dehyde and 3-t-butyldimethylsilyloxy-4-methoxybenzal-
dehyde (10) according to the procedure described above for
compounds 8, 9. Flash column chromatography (petroleum
ether/EtOAc 9:1) afforded oxirane 11 as a colourless oil
(274 mg, 9%). Rf 0.65 (petroleum ether/EtOAc 1:1). dH
(300 MHz) 0.18 [6 H, s, (CH3)2], 1.02 [9 H, s, (CH3)3], 3.73
(1 H, d, J = 1.9, CH), 3.80 (1 H, d, J = 1.9, CH), 3.84 (3 H, s,
OCH3), 3.87 (3 H, s, OCH3), 3.89 [6 H, s, (OCH3)2], 6.59
(2 H, s, H-2′,6′), 6.83 (1 H, d, J = 1.9, H-2″), 6.86 (1 H, d,
J = 8.3, H-5″), 6.92 (1 H, dd, J = 8.3, 1.9, H-6″). dC (100 MHz)
–4.2 (CH3), 18.9 (C), 26.1 (CH3), 56.0 (CH3), 56.5 (CH3),
61.3 (CH3), 63.1 (CH), 63.2 (CH), 102.5 (CH), 112.4 (CH),
118.4 (CH), 119.4 (CH), 129.8 (C), 133.3 (C), 138.3 (C),
145.7 (C), 151.7 (C), 154.0 (C). m/z (FAB) 447 [(MH)+, 50%],
417 {[M-(CH3)2]+ 60%}, 73 (100%).
5.1.1. 4-Methoxybenzaldehyde tosyl hydrazone sodium salt
(6)
To a solution of sodium methoxide (0.6 g, 26.1 mmol) in
MeOH (20 ml) was added 4-methoxybenzaldehyde tosyl
hydrazone 5 (8 g, 26.3 mmol) and the mixture stirred until
the solid had dissolved. After stirring for a further 15 min the
methanol was removed under reduced pressure to give the
title salt 6 [19] as a fine white powder (7.11 g, 72%). dH
(300 MHz, D2O) 2.19 (3 H, s, CH3), 3.63 (3 H, s, OCH3),
6.76 (2 H, d, J = 8.3, H-3″,5″), 7.19 (2 H, d, J = 8.3, H-3′,5′),
7.33 (2 H, d, J = 8.3, H-2″,6″), 7.57 (2 H, d, J = 8.3, H-2′,6′),
7.77 (1 H, s, CH).
5.1.2. Cis and trans 2-(3′,4′,5′-trimethoxyphenyl)-
3-(4″-ethylphenyl) oxirane (8, 9)
3,4,5-Trimethoxybenzaldehyde (2.51 g, 12.8 mmol) was
added to a solution of 4-toluenesulfonylhydrazide 7 (2.5 g,
13.4 mmol) in dry 1,4-dioxane (30 ml) at room temperature.
The solution was stirred for 30 min after which sodium
hydride (510 mg of 60% dispersion in oil, 12.8 mmol) was
added. The mixture was stirred for 1 h and rhodium(II) acetate
dimer (54 mg, 0.122 mmol), benzyltriethylammonium chlo-
5.1.4. Trans-2-(3′,4′,5′-Trimethoxyphenyl)-
3-(3″-hydroxy-4″-methoxyphenyl)oxirane (12)
To a stirred solution of TBDMS ether 11 (500 mg,
1.12 mmol) in dry THF (20 ml) was added tetra-n-
butylammonium fluoride (2 ml of 1 M solution in THF,

J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
535
2 mmol). The resulting yellow solution was stirred for 20 min
and treated with water (30 ml). The aqueous layer was sepa-
rated, extracted with chloroform (3 × 25 ml) and the com-
bined organic layers were washed with water (2 × 25 ml),
brine (25 ml), dried (MgSO4) and concentrated in vacuo. Flash
column chromatography (petroleum ether/EtOAc 9:1) af-
forded phenolic oxirane 12 as a colourless oil (272 mg, 73%).
Rf 0.34 (petroleum ether/EtOAc 1:1). dH (300 MHz) 3.76 (1 H,
d, J = 1.9, CH), 3.82 (1 H, d, J = 1.9, CH), 3.87 (3 H, s,
OCH3), 3.89 [6 H, s, (OCH3)2], 3.93 (3 H, s, OCH3), 5.73
(1 H, s, OH), 6.59 (2 H, s, H-2′,6′), 6.86–6.92 (3 H, m,
H-2″,5″,6″). dC (100 MHz) 55.0 (CH3), 55.1 (CH3), 59.9
(CH3), 61.6 (CH), 61.8 (CH), 101.1 (CH), 109.6 (CH), 110.4
(CH), 116.6 (CH), 129.1 (C), 131.8 (C), 136.8 (C), 144.9 (C),
145.8 (C), 152.5 (C). m/z (FAB) 333 [(MH)+, 25%], 303
(75%).
H-2′ and H-6′), 7.71 (1 H, s, C=CH). dC (DMSO-d6) 52.3
(OCH3), 55.3 (OCH3), 55.6 (OCH3), 60.8 (OCH3), 108.0,
114.2, 128.2, 130.0, 131.0, 138.7, 140.2, 152.5, 159.2 (CH
and C), 168.4 (CO2Me). m/z (EI) 359 [(M+H)+, 100%].
(Found: M+, 358.1420; C, 67.1; H, 6.0. C20H22O6 requires
M+, 358.1416; C, 67.0; H, 6.1%).
5.1.7. E-2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxyphe-
nyl)prop-2-en-1-ol (15)
To a stirred solution of cinnamic ester 14 (10 g, 0.028 mol)
in dry THF (100 ml) at –20 °C was added LiAlH4 powder
(4.25 g, 0.112 mol). The reaction mixture was stirred at room
temperature for 1 h before the careful addition of aqueous
solutions of THF, followed by the addition of water (the solu-
tion went from grey to white). The lithium salts were removed
by filtration. Water was added to the filtrate and the product
extracted with diethyl ether (3 × 50 ml). The organics were
washed with water (2 × 100 ml), brine (1 × 100 ml) and dried
over magnesium sulphate before concentrating under reduced
pressure to furnish the alcohol 15 as a yellow oily solid (8.88 g,
96%). Rf 0.62 (petroleum ether/EtOAc 1:1). mmax 3474 (b,
OH), 1581 (s, C=C), 1509 (s, C=C), 1126 (s, CO). dH (DMSO)
3.47 (6 H, s, 2 × OCH3), 3.57 (3 H, s, OCH3), 3.74 (3 H, s,
OCH3), 4.18 (2 H, dd, J = 5.7 and 1.6, CH2), 6.25 (2 H, s,
H-2″ and H-6″), 6.54 (1 H, d, J = 1.6, C=CH), 6.95 (2 H, d,
J = 8.8, H-3′ and H-5′), 7.11 (2 H, d, J = 8.8, H-2′ and H-6′).
dC 55.0 (OCH3), 55.3 (OCH3), 60.5 (OCH3), 68.2 (CH2),
106.0, 114.0, 125.6, 128.7, 129.7, 130.5, 131.7, 140.4, 152.0,
158.5 (CH and C). m/z (EI) 331 [(M + H)+, 100%]. (Found:
M+, 330.1464; C, 69.1; H, 6.8. C19H22O5 requires M+,
330.1467; C, 69.0; H, 6.7%).
5.1.5. E-2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxyphe-
nyl)acrylic acid (13)
A mixture of 3,4,5-trimethoxybenzaldehyde (11.8 g,
0.06 mol), 4-methoxyphenylacetic acid (20 g, 0.12 mol), tri-
ethylamine (25 ml) and acetic anhydride (50 ml) was heated
under reflux for 3 h After acidification with concentrated
hydrochloric acid (150 ml), the solid formed was removed by
filtration and recrystallised from ethanol to afford the cin-
namic acid 13 as a yellow solid (20.1 g, 97%). M.p. 200–
203 °C (lit. [21] m.p. 207–8 °C) Rf 0.56 (petroleum
ether/EtOAc 1:1). mmax 2967 (b, OH), 1676 (s, C=O), 1612
(s, C=C), 1499 (s, C=C). dH (DMSO-d6) 3.48 (6 H, s, 2 ×
OCH3), 3.61 (3 H, s, OCH3), 3.76 (3 H, s, OCH3), 6.42 (2 H,
s, H-2″ and H-6″), 6.99 (2 H, d, J = 8.7, H-3′ and H-5′), 7.11
(2 H, d, J = 8.7, H-2′ and H-6′), 7.67 (1 H, s, C=CH). dC
(DMSO-d6) 54.9 (OCH3), 55.8 (OCH3), 59.7 (OCH3), 107.7,
113.8, 128.3, 129.6, 130.5, 131.7, 137.9, 138.7, 152.0, 158.5
(CH and C), 168.3 (CO2H). m/z (EI) 345 [(M + H)+, 100%].
(Found: M+, 344.1267; C, 66.0; H, 5.8%. C19H20O6 requires
M+, 344.1259; C, 66.2; H, 5.8%).
5.1.8. E-2-[2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethox-
yphenyl)allyl]isoindole-1,3-dione (16)
Following a similar method to Hammerschmidt and Han-
bauer [22], diisopropyl azodicarboxylate (4.9 ml, 0.025 mol),
phthalimide (3.85 g, 0.025 mol) and triphenylphosphine
(5.60 g, 0.021 mol) were added to a solution of alcohol 15
(6.93 g, 0.021 mol) in THF (30 ml). The reaction mixture
was stirred at room temperature for 45 min, the THF removed
under reduced pressure and the residue purified by flash col-
umn chromatography (petroleum ether/EtOAc 2:1). The solid
obtained was further purified by recrystallisation from etha-
nol to yield the phthalimide 16 as white crystals (2.78 g, 30%).
M.p. 140–142 °C. Rf 0.67 (petroleum ether/EtOAc 1:1). mmax
1771 (s, C=C), 1716 (s, C=O), 1244 (s, CN). dH 3.45 (6 H, s,
2 × OCH3), 3.65 (6 H, s, 2 × OCH3), 4.60 (2 H, s, CH2), 6.15
(2 H, s, H-2″ and H-6″), 6.45 (1 H, s, C=CH), 6.75 (2 H, d,
J = 8.8, H-3′ and H-5′), 7.11 (2 H, d, J = 8.8, H-2′ and H-6′),
7.70 (2 H, dd, J = 5.4 and 5.6, phthalimide H), 7.82 (2 H, dd,
J = 5.4 and 5.6, phthalimide H). dC 45.4 (CH2), 55.5 (OCH3),
56.4 (2 × OCH3), 61.3 (OCH3), 106.2, 113.9, 125.6, 128.7,
129.5, 130.7, 131.9, 133 7, 134.3, 134.6, 137.8, 153.6 (CH
and C), 158.9, 168.3 (C=O). m/z (EI) 460 [(M + H)+ 100%].
(Found: M+, 459.1681; C, 70.4; H, 5.7; N, 3.1. C27H25NO6
requires M+, 459.1681; C, 70.5; H, 5.5; N, 3.1%).
5.1.6. E-2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxyphe-
nyl)acrylic acid methyl ester (14)
Concentrated sulphuric acid (40 ml) was added to a solu-
tion of acid 13 (21.6 g, 0.063 mol) in methanol (320 ml) and
the mixture was heated under reflux conditions for 45 min.
Upon cooling some ester 14 was formed as a solid and was
removed by filtration. The methanol solution was concen-
trated under reduced pressure, the residue dissolved in diethyl
ether and washed with water (20 ml) and sodium bicarbonate
(40 ml). The organics were dried over magnesium sulphate
before concentration under reduced pressure. The crude prod-
uct obtained was recrystallised from methanol to give the title
ester 14 as fine yellow crystals (14.4 g, 64%). M.p. 65–67 °C.
Rf 0.80 (petroleum ether/EtOAc 1:1). mmax 2950 (s, CH), 2838
(s, CH), 1709 (s, C=O), 1618 (s, C=C), 1508 (s, C=C). dH
3.48 (6 H, s, 2 × OCH3), 3.60 (3 H, s, OCH3), 3.77 (3 H, s,
OCH3), 3.78 (3 H, s, OCH3), 6.44 (2 H, s, H-2″ and H-6″),
6.99 (2 H, d, J = 8.7, H-3′ and H-5′), 7.09 (2 H, d, J = 8.7,

536
J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
5.1.9. E-2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxyphe-
nyl)allylamine (17)
30.1 (CH2), 47.2 (CH2), 55.5 (OCH3), 56.1 (2 × OCH3), 61.2
(OCH3), 106.8, 114.7, 127.6, 130.5, 131.2, 132.4, 137.4,
138.1, 152.9, 159.5 (CH and C), 173.8 (C=O). m/z (EI) 386
[(M + H)+, 100%]. (Found: M+ 385.1893. C22H27NO5
requires M+ 385.1889).
A solution of phthalimide 16 (1.69 g, 3.68 mmol) and
hydrazine hydrate (4.00 g, 12.14 mmol) in ethanol (25 ml)
was heated at 100 °C for 1.25 h The solid phthalimide
by-product formed was removed by filtration and the solu-
tion remaining was washed with ethanol, concentrated and
refiltered. Evaporation of the solvent afforded the amine 17
(857 mg, 71%) as a yellow oily solid. Rf 0.12 (MeOH/EtOAc
1:9). mmax 3378 (m, NH), 1605 (s, C=C), 1506 (s, C=C), 1242
(s, CN). dH (DMSO-d6) 3.44 (2 H, d, J = 1.6, CH2), 3.46 (6 H,
s, 2 × OCH3), 3.57 (3 H, s, OCH3), 3.74 (3 H, s, OCH3), 6.22
(2 H, s, H-2″ and H-6″), 6.50 (1 H, d, J = 1.6, C=CH), 6.95
(2 H, d, J = 8.7, H-3′ and H-5′), 7.05 (2 H, d, J = 8.7, H-2′
and H-6′). dC 50.7 (CH2), 55.0 (OCH3), 56.5 (2 × OCH3),
106.0, 114.0, 125.6, 129.7, 130.5, 135.7, 137.4, 153.9, 158.5
(CH and C). m/z (EI) 329 [(M)+ 40%]. (Found M+, 329.1624.
C19H23NO4 requires M+, 329.1627).
5.1.12. E-N-[2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxy-
phenylallyl]-2,2-dimethyl-propionamide (20)
Prepared according to procedureA from amine 17 (60 mg,
0.18 mmol) and trimethylacetyl chloride (27 µl, 0.22 mmol).
Purification by flash column chromatography (petroleum
ether/EtOAc 2:1) provided the title amide 20 as a cream
coloured solid (51 mg, 67%). M.p. 96–97 °C. Rf 0.41 (petro-
leum ether/EtOAc 1:1). mmax 3352 (b, NH), 1645 (s, C=O),
1510 (s, C=C). dH 1.10 (12 H, s, 3 × CH3), 3.57 (6 H, s, 2 ×
OCH3), 3.78 (3 H, s, OCH3), 3.80 (3 H, s, OCH3), 4.24 (2 H,
dd, J = 5.7 and 1.2, CH2), 5.39 (1 H, t, J = 5.7, NH), 6.23
(2 H, s, H-2″ and H-6″), 6.45 (1 H, d, J = 1.2, C=CH), 6.88
(2 H, d, J = 8.8, H-3′ and H-5′), 7.14 (2 H, d, J = 8.8, H-2′
and H-6′). dC 27.9 (CH3), 39.1 (CH2), 55.7 (OCH3), 56.1 (2 ×
OCH3), 61.2 (OCH3), 98.5, 106.8, 114.7, 130.5, 131.2, 132.3,
152.9, 159.5 (CH and C), 173.5 (C=O). m/z (EI) 414 [(M +
H)+, 100%]. (Found: M+ 413.2199; C, 69.8; H, 7.6; 3.7.
C24H31NO5 requires M+ 413.2202; C, 69.7; 7.5; 3.4%).
5.1.10. E-N-[2-(4-Methoxyphenyl)-3-(3,4,5-trimethoxyphe-
nyl)allyl]acetamide (18)
Procedure A: To a solution of aminostilbene 17 (158 mg,
0.480 mmol) and pyridine (2.4 mmol) in chloroform (15 ml)
was added acetyl chloride (41 µl, 0.576 mmol. After stirring
for 1 h the solution was washed with aqueous hydrochloric
acid (0.1 M, 2 × 30 ml), water (10 ml) and brine (10 ml).
After drying (MgSO4) and removal of the solvent the fol-
lowed by purification by flash column chromatography (petro-
leum ether/EtOAc 1:1) the target compound 18 was isolated
as a brown oil (100 mg, 56%). Rf 0.24 (petroleum ether/EtOAc
1:2); mmax (neat) 3294 (s, NH), 2938 (s), 1663 (s, C=O), 1581
(s), 1513 (s), 1416 (s), 1243 (s), 1123 (s). dH 1.95 (3 H, s,
CH3), 3.56 (6 H, s, 2 × OCH3), 3.77 (3 H, s, OCH3), 3.79
(3 H, s, OCH3), 4.23 (2 H, d, J = 5.7, CH2), 5.51 (1 H, t J = 5.7,
NH), 6.21 (2 H, s, H-2′ and H-6′), 6.46 (1 H, s, C=CH), 6.88
(2 H, d, J = 8.8, H-3″ and H-5″), 7.15 (2 H, d, J = 8.8, H-2″and
H-6″). dC 23.6 (CH3), 47.7 (CH2), 55.7 (OCH3), 56.0 (2 ×
OCH3), 61.2 (OCH3), 106.7 (CH), 114.4 (CH), 127.9 (CH),
130.4 (CH), 131.1, 132.3, 137.2, 137.9, 153.2, 159.5, 170.3
(C=O) ppm. m/z (EI) 372 [(M+H)+, 25%]. (Found: M+,
371.1726. C21H25NO5 requires M+, 371.1727).
5.1.13. E-2-Chloro-N-[2-(4′-methoxyphenyl)-3-(3″,4″,5″-
trimethoxy-phenyl)-allyl]-acetamide (21)
Prepared according to procedureA from amine 17 (60 mg,
0.18 mmol) and chloroacetyl chloride (17 µl, 0.22 mmol).
Purification by flash column chromatography (petroleum
ether/EtOAc 2:1) provided the title amide 21 as a pale yellow
solid (18 mg, 24%). M.p. 115–117 °C. Rf 0.35 (petroleum
ether/EtOAc 1:1). mmax 3309 (b, NH), 1665 (s, C=O), 1511
(s, C=C), 1244 (s, CN), 733 (w, CCl). dH 3.57 (6 H, s, 2 ×
OCH3), 3.78 (3 H, s, OCH3), 3.80 (3 H, s, OCH3), 4.03 (2 H,
s, CH2Cl), 4.28 (2 H, d, J = 5.7, CH2), 6.23 (2 H, s, H-2″ and
H-6″), 6.48 (1 H, s, C=CH), 6.68 (1 H, t, J = 5.7, NH), 6.89
(2 H, d, J = 8.7, H-3′ and H-5′), 7.16 (2 H, d, J = 8.7, H-2′
and H-6′). dC 35.1 (CH2), 47.2 (CH2), 55.7 (OCH3), 56.1 (2 ×
OCH3), 61.2 (OCH3), 100.0, 106.8, 114.7, 130.8, 131.2,
132.4, 137.4, 138.1, 152.9, 159.5, 166.0 (CH and C), 173.5
(C=O). m/z (EI) 406 [(M + H)+, 100%]. (Found: M+ 405.1342;
C, 62.0; H, 6.1; N, 3.5. C21H24ClNO5 requires M+ 405.1343;
C, 62.0; H, 5.9; N, 3.5%).
5.1.11. E-N-[2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxy-
phenyl)allyl]propionamide (19)
Prepared according to procedureA from amine 17 (60 mg,
0.18 mmol) and propionyl chloride (19 µl, 0.22 mmol). Puri-
fication by flash column chromatography (petroleum
ether/EtOAc 1:1) provided the title amide 19 as a cream solid
(48 mg, 69%). M.p. 115–117 °C. Rf 0.2 (petroleum
ether/EtOAc 1:1). mmax 3295 (b, NH), 1642 (s, C=O), 1510
(s, C=C), 1245 (s, CN). dH 1.10 (3 H, t, J = 7.6, CH3), 2.16
(2 H, q, J = 7.6, CH2CH3), 3.57 (6 H, s, 2 × OCH3), 3.78
(3 H, s, OCH3), 3.80 (3 H, s, OCH3), 4.26 (2 H, dd, J = 5.7 and
1.2, CH2), 5.49 (1 H, s, NH), 6.22 (2 H, s, H-2″ and H-6″),
6.45 (1 H, d, J = 1.2, C=CH), 6.88 (2 H, d, J = 8.8, H-3′ and
H-5′), 7.15 (2H, d, J = 8.8, H-2′ and H-6′). dC 10.4 (CH3),
5.1.14. E-2-(4-Chlorophenyl)-N-[2-(4′-methoxyphenyl)-3-
(3″,4″,5″-trimethoxyphenyl)-allyl]acetamide (22)
Prepared according to procedureA from amine 17 (86 mg,
0.26 mmol) and 4-chlorophenylacetyl chloride (60 mg,
0.31 mmol). Purification by flash column chromatography
(petroleum ether/EtOAc 1:1) provided amide 22 as a yellow
solid (84 mg, 67%). M.p. 128–130 °C. Rf 0.22 (petroleum
ether/EtOAc 1:1). mmax 3292 (b, NH), 1648 (s, C=O), 1509
(s, C=C), 1244 (s, CN). dH 3.47 (2 H, CH2Ar), 3.55 (6 H, s, 2
× OCH3), 3.77 (3 H, s, OCH3), 3.81 (3 H, s, OCH3), 4.22
(2 H, d, J = 5.4, CH2), 5.35 (1 H, t, J = 5.4, NH), 6.17 (2 H, s,

J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
537
H-2″ and H-6″), 6.36 (1 H, s, C=CH), 6.83 (2 H, d, J = 8.7,
5.1.17. E-3,3,3-Trifluoro-N-[2-(4′-methoxyphenyl)-3-
(3″,4″,5″-trimethoxyphenyl)allyl]propionamide (25)
H-3′ and H-5′), 7.01 (2 H, d, J = 8.2, H-2, and H-6), 7.02
(2 H, d, J = 8.7, H-2′ and H-6′), 7.23 (2 H, d, J = 8.2, H-3 and
H-5). dC 42.8 (CH2), 46.9 (CH2), 55.3 (OCH3), 56.1 (2 ×
OCH3), 60.5 (OCH3), 99.3, 106.0, 113.9, 127.2, 128.7, 129.6,
130.3, 131.4, 136.9, 152.2, 158.8 (CH and C), 169.7 (C=O).
m/z (EI) 482 [(M + H)+, 100%]. (Found: M+ 481.1664; C,
67.2; H, 6.2; N, 3.2; Cl, 7.2. C27H28ClNO5 requires M+
481.1656; C, 67.2; H, 5.8; N, 2.9; Cl, 7.3%).
Prepared according to procedure B from amine 17 (90 mg,
0.27 mmol) and 3,3,3-trifluoropropionic acid (24 µl,
0.27 mmol). Purification by flash column chromatography
(petroleum ether/EtOAc 2:1) gave amide 25 as a cream
coloured solid (39 mg, 49%). M.p. 132–135 °C. Rf 0.45
(petroleum ether/EtOAc 1:1). mmax 3309 (b, NH), 1665 (s,
C=O), 1510 (s, C=C), 1243 (s, CN), 665 (m, CF). dH 3.57
(6 H, s, 2 × OCH3), 3.78 (3 H, s, OCH3), 3.80 (3 H, s, OCH3),
3.86 (2 H, s, CH2), 4.30 (2 H, dd, J = 5.9 and 1.2, CH2), 5.82
(1 H, t, J = 5.9, NH), 6.22 (2 H, s, H-2″ and H-6″), 6.48 (1 H,
d, J = 1.2, C=CH), 6.88 (2 H, d, J = 8.9, H-3′ and H-5′), 7.15
(2 H, d, J = 8.9, H-2′ and H-6′). dC 13.8 (CF3), 20.4 (CH2),
47.2 (CH2), 55.5 (OCH3), 56.1 (2 × OCH3), 61.3 (OCH3),
127.9, 128.5, 130.5, 130.6, 132.0, 136.9, 152.9. m/z (EI) 440
[(M+H)+, 100%]. (Found: M+ 439.1893; C, 60.2; H, 5.8; N,
3.4; F, 12.6%. C22H24F3NO5 requires M+ 439.1889; C, 60.1;
H, 5.5; N, 3.2; F, 12.9%).
5.1.15. E-N-[2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxy-
phenyl)allyl]isobutyramide (23)
Procedure B: To a solution of 1-[3-(dimethyl-
amino)propyl]-3-ethylcarbodiimide hydrochloride (35 mg,
0.18 mmol), 1-hydroxybenzotriazole (25 mg, 0.18 mmol) and
isobutyric acid (17 µl, 0.18 mmol) in DMF, amine 17 (60 mg,
0.18 mmol) and N-ethyldiisopropylamine (95 µl, 0.55 mmol)
were added. The solution was stirred overnight, ethyl acetate
(10 ml) added and washed with water (10 ml), hydrochloric
acid (0.1 M, 10 ml) and saturated sodium bicarbonate solu-
tion (10 ml). The organics were dried over magnesium sul-
phate and concentrated under reduced pressure. Purification
by flash column chromatography (petroleum ether/EtOAc 1:1)
gave amide 23 as a cream coloured solid (49 mg, 67%). M.p.
122–124 °C. Rf 0.28 (petroleum ether/EtOAc 1:1). mmax 3307
(b, NH), 1657 (s, C=O), 1601 (s, C=C), 1245 (s, CN).
kmax = 278 (e = 9380). dH 1.06 (6 H, d, J = 6.9, 2 × CH3),
2.29 (1 H, septet, J = 6.9, CH), 3.57 (6 H, s, 2 × OCH3), 3.74
(3 H, s, OCH3), 3.79 (3 H, s, OCH3), 4.25 (2 H, dd, J = 5.7 and
1.2, CH2), 5.53 (1 H, t, J = 5.7, NH), 6.22 (2 H, s, H-2″ and
H-6″), 6.46 (1 H, d, J = 1.2, C=CH), 6.87 (2 H, d, J = 8.8,
H-3′ and H-5′), 7.14 (2 H, d, J = 8.8, H-2′ and H-6′). dC 19.9
(3 × CH3), 36.1 (CH), 47.5 (CH2), 55.7 (OCH3), 56.2 (2 ×
OCH3), 61.2 (OCH3), 106.9, 112.0, 114.7, 127.3, 128.0,
130.5, 131.1, 132.3, 137.4, 138.2, 152.9, 159.5 (CH and C),
177.3 (C=O). m/z (EI) 400 [(M + H)+, 100%]. (Found: M+
399.2044. C23H29NO5 requires M+ 399.2046).
5.1.18. E-N-[3-(4′-Methoxyphenyl)-2-(3″,4″,5″-trimethoxy-
phenyl)allyl]acetamide (27)
Acetamide 27 was prepared according to procedureA from
amine 26 [21] (110 mg, 0.33 mmol) and acetyl chloride (24 µl,
0.33 mmol) as a cream coloured solid (25 mg, 20%) from
diethyl ether. Product decomposition before m.p. reached. Rf
0.23 (petroleum ether/EtOAc 1:1). 3294 (b, NH), 1652 (s,
C=O), 1510 (s, C=C), 1249 (s, CN), 1032 (m, CN). dH 1.98
(3 H, s, CH3), 3.71 (6 H, s, 2 × OCH3), 3.75 (3 H, s, OCH3),
3.80 (3 H, s, OCH3), 4.25 (2 H, d, J = 5.7 Hz, CH2), 5.48
(1 H, t, J = 5.7, NH), 6.38 (2 H, s, H-2″ and H-6″), 6.45 (1 H,
s, C=CH), 6.68 (2 H, d, J = 8.8, H-3′ and H-5′), 6.92 (2 H, d,
J = 8.8, H-2′ and H-6′). dC 23.8 (CH3), 47.5 (CH2), 55.6
(OCH3), 56.5 (2 × OCH3), 61.3 (OCH3), 106.2, 114.1, 127.8,
129.2, 130.8, 134.4, 136.4, 137.8, 153.7, 158.9 (CH and C),
170.2 (C=O). m/z (EI) 371 [(M)+ 100%]. (Found M+,
371.1736. C21H25NO5 requires M+, 371.1733).
5.1.16. E-N-[2-(4′-Methoxyphenyl)-3-(3″,4″,5″-trimethoxy-
phenyl)allyl]butyramide (24)
5.1.19. E-N-[3-(4′-Methoxyphenyl)-2-(3″,4″,5″-trimethoxy-
phenyl)allyl]propionamide (28)
Prepared according to procedure B from amine 17 (60 mg,
0.18 mmol) and butyric acid (17 µl, 0.18 mmol). Purification
by flash column chromatography (petroleum ether/EtOAc 1:1)
gave amide 24 as a yellow crystalline solid (55 mg, 75%).
M.p. 79–80 °C. Rf 0.18 (petroleum ether/EtOAc 1:1). mmax
3287 (b, NH), 1650 (s, C=O), 1510 (s, C=C), 1245 (s, CN).
dH 0.87 (3 H, t, J = 7.4, CH3), 1.58 (2 H, m, CH2CH3), 2.11
(2 H, t, J = 7.5, COCH2), 3.57 (6 H, s, 2 × OCH3), 3.78 (3 H,
s, OCH3), 3.87 (3 H, s, OCH3), 4.26 (2 H, dd, J = 5.7 and 1.2,
CH2), 5.52 (1 H, t, J = 5.7, NH), 6.22 (2 H, s, H-2″ and H-6″),
6.45 (1 H, d, J = 1.2, C=CH), 6.87 (2 H, d, J = 8.7, H-3′ and
H-5′), 7.15 (2 H, d, J = 8.7, H-2′ and H-6′). dC19.7 (CH3),
39.3 (CH2), 43.5 (CH2), 55.5 (OCH3), 56.2 (2 × OCH3), 61.2
(OCH3), 100.2, 107.0, 114.7, 127.8, 128.0, 130.4, 138.1,
152.9, 155.5 (CH and C), 173.3 (C=O). m/z (EI) 400 [(M +
H)+, 100%]. (Found: M+ 399.2046. C23H29NO5 requires M+
399.2046).
Prepared according to procedureA from amine 26 (60 mg,
0.18 mmol) and propionyl chloride (21 µl, 0.24 mmol).
Recrystallisation from ethanol yielded the title amide 28 as a
white solid (18 mg, 26%). M.p. 141–144 °C. Rf 0.13 (petro-
leum ether/EtOAc 1:1). mmax 3307 (b, NH), 1647 (s, C=O),
1510 (s, C=C), 1249 (s, CN), 1032 (m, CN). dH 1.10 (3 H, t,
J = 7.6, CH3), 2.17 (2 H, q, J = 7.6, CH2CH3), 3.73 (6 H, s, 2
× OCH3), 3.78 (3 H, s, OCH3), 3.87 (3 H, s, OCH3), 4.27
(2 H, dd, J = 5.7 and 1.2, CH2), 5.48 (1 H, t, J = 5.7, NH),
6.42 (2 H, s, H-2″ and H-6″), 6.49 (1 H, s, C=CH), 6.68 (2 H,
d, J = 8.7, H-3′ and H-5′), 6.95 (2 H, d, J = 8.7, H-2′ and
H-6′). dC 10.3 (CH3), 30.2 (CH2), 47.3 (CH2), 55.5 (OCH3),
56.5 (2 × OCH3), 61.3 (OCH3), 106.2, 113.8, 127.6, 129.3,
130.8, 134.4, 136.6, 137.8, 153.8, 158.9 (CH and C), 173.8
(C=O). m/z (EI) 386 [(M+H)+, 100%]. (Found: M+ 385.1887;
C, 68.4; H, 7.2; N, 3.6. C22H27NO5 requires M+ 385.1889; C,
68.4; H, 7.0; N, 3.6%).

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J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
5.1.20. E-N-[3′-(4-Methoxyphenyl)-2-(3″,4″,5″-trimethoxy-
phenyl)-2,2-dimethyl-propionamide (29)
(C=O). m/z (EI) 434 [(M + H)+, 100%]. (Found M+ 433.1892;
C, 72.1; H, 6.3; N, 3.1. C26H27NO5 requires M+ 433.1889; C,
72.0; H, 6.2; N, 3.2%).
Prepared according to procedureA from amine 26 (60 mg,
0.18 mmol) and trimethylacetyl chloride (29 µl, 0.24 mmol).
Flash column chromatography (petroleum ether/EtOAc 2:1)
provided the title amide 29 as a pale yellow solid (38 mg,
50%). M.p. 128–129 °C. Rf 0.27 (petroleum ether/EtOAc 2:1).
mmax 3355 (b, NH), 1645 (s, C=O), 1510 (s, C=C), 1249 (s,
CN), 1030 (m, CN). dH 1.10 (12 H, s, 3 × CH3), 3.73 (6 H, s,
2 × OCH3), 3.78 (3 H, s, OCH3), 3.85 (3 H, s, OCH3), 4.26
(2 H, dd, J = 5.9 and 0.9, CH2), 5.67 (1 H, t, J = 5.9, NH),
6.42 (2 H, s, H-2″ and H-6″), 6.47 (1 H, d, J = 0.9, C=CH),
6.68 (2 H, d, J = 8.7, H-3′ and H-5′), 6.96 (2 H, d, J = 8.7,
H-2′ and H-6′). dC 27.9 (CH3), 39.1 (CH2), 55.6 (OCH3), 56.5
(2 × OCH3), 61.4 (OCH3), 100.0, 106.2, 113.8, 127.3, 129.3,
130.8, 134.5, 137.1, 153.9, 159.9 (CH and C), 178.4 (C=O).
m/z (EI) 414 [(M + H)+, 100%]. (Found: M+ 413.2207; C,
69.4; H, 7.7; N, 3.4%. C24H31NO5 requires M+ 413.2202; C,
69.6; H, 7.5; N, 3.4%).
5.1.23. E-2-(4-Chlorophenyl)-N-[3-(4′-methoxyphenyl)-2-
(3″,4″,5″-trimethoxyphenyl)-allyl]acetamide (32)
Prepared according to procedureA from amine 26 (60 mg,
0.18 mmol) and 4-chlorophenylacetyl chloride (34 mg,
0.22 mmol). Recrystallisation from ethanol afforded the title
amide 32 as a white solid (30 mg, 35%). M.p. 114–116 °C. Rf
0.41 (petroleum ether/EtOAc 1:1). mmax 3292 (b, NH), 1647
(s, C=O), 1509 (s, C=C), 1250 (s, CN), 1016 (m, CN), 735
(m, CCl). dH 3.47 (2 H, CH2Ar), 3.69 (6 H, s, 2 × OCH3),
3.74 (3 H, s, OCH3), 3.89 (3 H, s, OCH3), 4.24 (2 H, d, J = 5.4,
CH2), 5.34 (1 H, t, J = 5.4, NH), 6.31 (2 H, s, H-2″ and H-6″),
6.38 (1 H, s, C=CH), 6.66 (2 H, d, J = 8.9, H-3′ and H-5′),
6.90 (2 H, d, J = 8.9, H-2′ and H-6′), 6.99 (2 H, d, J = 8.5,
H-2 and H-6), 7.23 (2 H, d, J = 8.5, H-3 and H-5). dC 43.5
(CH2), 47.5 (CH2), 55.6 (OCH3), 56.5 (2 × OCH3), 61.4
(OCH3), 99.4, 106.1, 113.8, 127.8, 129.0, 129.4, 130.8, 131.1,
133.5, 136.1, 153.9, 159.0 (CH and C), 170.5 (C=O). m/z
(EI) 482 [(M + H)+, 100%]. (Found: M+ 481.1653; C, 67.2;
H, 5.8; N, 2.9; Cl, 7.5. C27H28ClNO5 requires M+ 481.1656,
C, 67.2; H, 5.8; N, 2.9; Cl, 7.4%).
5.1.21. E-2-Chloro-N-[3-(4′-methoxyphenyl)-2-(3″,4″,5″-
trimethoxyphenyl)-allyl]acetamide (30)
Prepared according to procedureA from amine 26 (56 mg,
0.17 mmol) and chloroacetyl chloride (20 µl, 0.22 mmol).
Flash column chromatography (petroleum ether/EtOAc 2:1)
provided the title amide 30 as pale yellow crystals (18 mg,
25%). M.p. 120–121 °C. Rf 0.36 (petroleum ether/EtOAc 1:1).
mmax 3316 (b, NH), 1671 (s, C=O), 1509 (s, C=C), 1250 (s,
CN), 736 (w, CCl). dH 3.75 (6 H, s, 2 × OCH3), 3.78 (3 H, s,
OCH3), 3.88 (3 H, s, OCH3), 4.04 (2 H, s, CH2Cl), 4.28 (2 H,
d, J = 5.4, CH2), 5.34 (1 H, t, J = 5.4, NH), 6.41 (2 H, s, H-2″
and H-6″), 6.52 (1 H, s, C=CH), 6.68 (2 H, d, J = 8.7, H-3′
and H-5′), 6.95 (2 H, d, J = 8.7, H-2′ and H-6′). dC 43.0 (CH2),
47.8 (CH2), 55.5 (OCH3), 56.4 (2 × OCH3), 61.3 (OCH3),
105.9, 113.8, 128.3, 128.8, 130.7, 135.5, 154.0, 159.0, 165.9
(CH and C), 173.5 (C=O). m/z (EI) 406 [(M + H)+, 50%].
(Found M+ 405.1346; C, 62.0; H, 6.2; N, 3.4. C21H24ClNO5
requires M+ 405.1343; C, 62.0; H, 5.9; N, 3.4%).
5.1.24. 1-(3′-t-Butyldimethylsilyloxy-4′-methoxyphenyl)pro-
pene (33)
Potassium bis(trimethylsilyl)amide (34 ml of 0.5 M solu-
tion in toluene, 17 mmol) was added to ethyltriphenylphos-
phonium bromide (6.31 g, 17 mmol) in THF (150 ml) under
argon at 0 °C. The mixture was stirred at 0 °C for 2 h, cooled
to –78 °C and 3-t-butyldimethylsilyloxy-4-methoxybenzal-
dehyde 10 (2.74 g, 17 mmol) added. The resulting mixture
was stirred at –78 °C for 2 h and allowed to warm to room
temperature. Water (50 ml) was carefully added and the aque-
ous layer separated and extracted with ether (3 × 50 ml). The
combined organic layers were washed with water (2 × 50 ml),
brine (50 ml), dried (MgSO4) and concentrated in vacuo. Flash
column chromatography (petroleum ether/EtOAc 9:1) af-
forded a mixture of the two isomers, 33Z and 33E, as a colour-
less oil (2.88 g, 63%). Rf 0.76 (petroleum ether/EtOAc 8:3).
dH (300 MHz) 0.17 [6 H, s, (CH3)2 33E], 0.18 [6 H, s, (CH3)2
33Z], 1.01 [9H, s (CH3)3 33E], 1.02 [9H, s (CH3)3 33Z], 1.86
(3 H, dd, J = 6.4, 1.5, CH3 33E), 1.91 (3 H, dd, J = 6.4, 1.5,
CH3 33Z), 3.80 (3 H, s, OCH3 33E), 3.83 (3 H, s, OCH3
33Z), 5.70 (1 H, dq, J = 12.1, 6.4, olefinic H 33Z), 6.07 (1 H,
dq, J = 16.1, 6.4, olefinic H 33E), 6.27 (1 H, dd, J = 16.1,
1.5, olefinic H 33E), 6.34 (1 H, dd, J = 12.1, 1.5, olefinic H
33Z), 6.85–7.24 (6 H, m, H-2′,5′,6′ 33Z and 33E). Ratio
33Z/33E, 15:1. m/z (FAB) 279 [(MH)+, 20%], 73
{[C(CH3)3H]+ 100%}. (Found: (MH)+ 279.1774. C16H26O2Si
requires (MH)+ 279.1780).
5.1.22. E-N-[3-(4′-Methoxyphenyl)-2-(3″,4″,5″-trimethoxy-
phenyl)allyl]benzamide (31)
Prepared according to procedureA from amine 26 (56 mg,
0.17 mmol) and benzoyl chloride (28 µl, 0.22 mmol). Flash
column chromatography (petroleum ether/EtOAc 2:1) pro-
vided the title amide 31 as a yellow solid (51 mg, 32%). M.p.
147–149 °C. Rf 0.48 (petroleum ether/EtOAc 1:1). mmax 3325
(b, NH), 1640 (m, C=O), 1510 (s, C=C), 1249 (s, CN). kmax
270 (e = 15,900). dH 3.71 (6 H, s, 2 × OCH3), 3.75 (3 H, s,
OCH3), 3.87 (3 H, s, OCH3), 4.47 (2 H, d, J = 5.9, CH2), 6.18
(1 H, t, J = 5.9, NH), 6.47 (2 H, s, H-2″ and H-6″), 6.59 (1 H,
s, C=CH), 6.69 (2 H, d, J = 8.8, H-3′ and H-5′), 6.96 (2 H, d,
J = 8.8, H-2′ and H-6′), 7.41 (2 H, dd, J = 7.1 and 7.5, H-3 and
H-5), 7.49 (1 H, t, J = 7.5, H-4), 7.67 (2 H, d, J = 7.1, H-2 and
H-6). dC 48.0 (CH2), 55.6 (OCH3), 56.5 (2 × OCH3), 61.4
(OCH3), 106.2, 113.8, 127.2, 128.0, 129.0, 129.2, 130.8,
131.9, 134.5, 135.0, 136.4, 154.0, 159.0 (CH and C), 167.7
5.1.25. 1-(3′-Hydroxy-4′-methoxyphenyl)propene (34)
Phenols 34Z and 34E were prepared from the TBDMS
ethers, 34Z and 34E, (1 g, 3.6 mmol) as in the procedure

J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
539
described for phenol 12. Flash column chromatography
5.1.27. Z-2-(3′,4′,5′-Trimethoxyphenyl)-3-(3″-hydroxy-4″-
(petroleum ether/EtOAc 4:1) afforded the mixture of the two
isomers (34Z and 34E) as a colourless oil (381 mg, 65%). Rf
0.80 (petroleum ether/EtOAc 1:1). dH (300 MHz) 1.87 (3 H,
dd, J = 6.4, 1.5, CH3 34E), 1.92 (3 H, dd, J = 6.4, 1.5, CH3
34Z), 3.90 (3 H, s, OCH3 34E), 3.92 (3 H, s, OCH3 34Z),
5.58 (1 H, d, J = 1.1, OH 34E), 5.60 (1 H, d, J = 1.1, OH
34Z), 5.72 (1 H, dq, J = 12.1, 6.4, olefinic H 34Z), 6.11 (1 H,
dq, J = 16.1, 6.4, olefinic H 34E), 6.29 (1 H, dd, J = 16.1,
1.5, olefinic H 34E), 6.35 (1 H, dd, J = 12.1, 1.5, olefinic H
34Z), 6.83 (4 H, m, H-5′,6′ 34Z and 34E), 6.95 (2 H, d,
J = 1.9, H-2′ 34Z), 6.98 (2 H, d, J = 1.9, H-2′ 34E); Ratio
34Z/34E, 16:1. m/z (FAB) 164 (M+, 100%). (Found: M+
164.0839. C10H12O2 requires M+ 164.0837).
methoxyphenyl)prop-2-ene (36)
Z-Phenol 36 was prepared from TBDMS ether 35 (111 mg,
0.250 mmol) by the method used to make phenol 12 from
silylether 11. Flash column chromatography (petroleum
ether/EtOAc 2:1) and recrystallisation from EtOAc afforded
phenol 36 as a fine white powder (49 mg, 60%). M.p. 156–
158 °C. Rf 0.36 (petroleum ether/EtOAc 2:1). kmax (MeOH)
270 (e = 11,524). dH (300 MHz) 2.18 (3 H, d, J = 1.5, CH3),
3.75 [6 H, s, (OCH3)2], 3.84 (3 H, s, OCH3), 3.88 (3 H, s,
OCH3), 5.42 (1 H, s, OH), 6.36 (1 H, d, J = 1.5, olefinic H),
6.43 (2 H, s, H-2′,6′) 6.48 (1 H, dd, J = 8.3, 2.3, H-6″), 6.62
(1 H, d, J = 8.3, H-5″), 6.63 (1 H, d, J = 2.3, H-2″); dC
(100 MHz) 27.4 (CH3), 56.3 (CH3), 56.5 (CH3), 61.4 (CH3),
105.7 (CH), 110.5 (CH), 115.4 (CH), 121.3 (CH), 126.4 (CH),
131.5 (C), 137.3 (C), 137.4 (C), 138.0 (C), 145.3 (C), 145.5
(C), 153.6 (C). m/z (FAB) 330 (M+, 95%). (Found: M+
330.1469; C, 68.9; H, 7.0. C19H22O5 requires M+ 330.1467 C,
69.1; H, 6.7%).
5.1.26. Z- and E-2-(3′,4′,5′-Trimethoxyphenyl)-3-(3″-t-
butyldimethylsilyloxy-4″-methoxyphenyl)prop-2-ene (35,
39)
To a slurry of phosphonium bromide 37 [23] (1 g,
1.69 mmol) in THF (15 ml) under argon was added
n-butyllithium (1.25 ml of 1.6 M solution, 2 mmol) at –15 °C.
The resulting red anion was stirred for 20 min and 3,4,5-
trimethoxyacetophenone (38) (355 mg, 1.69 mmol) added.
The resultant solution was stirred at room temperature for 1 h
and water (5 ml) carefully added. The aqueous layer was sepa-
rated and extracted with ether (3 × 10 ml). The combined
organic layers were washed with water (2 × 10 ml), brine
(10 ml), dried (MgSO4) and concentrated in vacuo. Follow-
ing flash column chromatography (petroleum ether/EtOAc
19:1), Z stilbene 35 was isolated as a colourless oil (109 mg,
15%). Rf 0.72 (petroleum ether/EtOAc 1:1). kmax (MeOH)
270 (e = 7607). dH (300 MHz) 0.01 [6 H, s, (CH3)2], 0.92
[9 H, s, (CH3)3], 2.17 (3 H, d, J = 1.5, CH3), 3.75 [6 H, s,
(OCH3)2], 3.76 (3 H, s, OCH3), 3.87 (3 H, s, OCH3), 6.35
(1 H, d, J = 1.5, olefinic H), 6.42 (2 H, s, H-2′,6′) 6.52 (1 H,
d, J = 1.9, H-2″), 6.62 (1 H, dd, J = 8.3, 1.9, H-6″), 6.67 (1 H,
d, J = 8.3, H-5″); dC (100 MHz) –4.5 (CH3), 18.6 (C), 26.0
(CH3), 27.6 (CH3), 55.8 (CH3), 56.4 (CH3), 61.2 (CH3), 105.4
(CH), 111.8 (CH), 121.4 (CH), 123.1 (CH), 126.4 (CH), 130.9
(C), 137.1 (C), 137.2 (C), 138.4 (C), 144.7 (C), 150.4 (C),
153.6 (C). m/z (FAB) 445 [(MH+), 40%], 73 (100%). (Found:
M+ 444.2329; C, 67.3; H, 8.4. C25H36O5Si requires M+
444.2332; C, 67.5; H, 8.2%). Further elution afforded E stil-
bene 39 as a colourless oil (258 mg, 34%). Rf 0.67 (petro-
leum ether/EtOAc 1:1). kmax (MeOH) = 296 (e = 16,541). dH
(300 MHz) 0.20 [6 H, s, (CH3)2], 1.03 [9 H, s, (CH3)3], 2.28
(3 H, d, J = 1.1, CH3), 3.85 (3 H, s, OCH3), 3.89 (3 H, s,
OCH3), 3.93 [6 H, s, (OCH3)2], 6.69 (1 H, d, J = 1.1, olefinic
H), 6.72 (2 H, s, H-2′,6′) 6.87 (1 H, d, J = 8.3, H-5″), 6.91
(1 H, d, J = 2.3, H-2″), 6.95 (1 H, dd, J = 8.3, 2.3, H-6″); dC
(100 MHz) –4.2 (CH3), 18.3 (CH3), 18.9 (C), 26.2 (CH3),
55.9 (CH3), 56.6 (CH3), 61.3 (CH3), 103.7 (CH), 112.1 (CH),
122.2 (CH), 123.3 (CH), 127.6 (CH), 131.6 (C), 136.4 (C),
137.6 (C), 140.7 (C), 144.9 (C), 150.2 (C), 153.4 (C). m/z
(FAB) 445 [(MH+), 20%], 73 (100%). (Found: M+ 444.2333;
C, 67.3; H, 8.4. C25H36O5Si requires M+ 444.2332; C, 67.5;
H, 8.2%).
5.1.28. E-2-(3′,4′,5′-Trimethoxyphenyl)-3-(3″-hydroxy-4″-
methoxyphenyl)-prop-2-ene (40)
E-Phenol 40 was prepared from TBDMS ether 39 (156 mg,
0.351 mmol) by the method used to make phenol 12. Flash
column chromatography (petroleum ether/EtOAc 2:1) and
recrystallisation from EtOAc afforded phenol 40 as a white
solid (106 mg, 91%). M.p. 116–117 °C. Rf 0.36 (petroleum
ether/EtOAc 2:1). kmax (MeOH) 290 (e = 21,161). dH
(400 MHz, acetone-d6) 2.28 (3 H, d, J = 1.5, CH3), 3.76 (3 H,
s, OCH3), 3.88 (3 H, s, OCH3), 3.90 [6 H, s, (OCH3)2], 6.79
(1 H, d, J = 1.5, olefinic H), 6.85 (2 H, s, H-2′,6′), 6.87 (1 H,
dd, J = 8.0, 2.0, H-6″), 6.93 (1 H, d, J = 2.0, H-2″), 6.93 (1 H,
d, J = 8.0, H-5″); dC (100 MHz) 18.2 (CH3), 56.4 (CH3), 56.6
(CH3), 61.3 (CH3), 103.8 (CH), 110.8 (CH), 115.7 (CH),
121.7 (CH), 127.5 (CH), 132.1 (C), 136.8 (C), 137.8 (C),
140.6 (C), 145.6 (C), 145.7 (C), 153.4 (C). m/z (FAB) 330
(M+, 65%). (Found: M+ 330.1472; C, 69.1; H, 6.7. C19H22O5
requires M+ 330.1467; C, 69.3; H, 6.7%).
5.1.29. Z- and E-3-(3′,4′,5′-Trimethoxyphenyl)-4-(3′-t-
butyldimethylsilyloxy-4′-methoxyphenyl)but-3-ene (42, 43)
The stilbenes 42 and 43 were prepared from phosphonium
bromide 37 (2 g, 3.37 mmol) and 1-(3′,4′,5′-trimethoxy-
phenyl)propan-1-one (41) [12] (755 mg, 3.37 mmol) by the
procedure described for ethers 35, 39. Following flash col-
umn chromatography (petroleum ether/EtOAc 19:1), Z stil-
bene 42 was isolated as a colourless oil (170 mg, 11%). Rf
0.35 (petroleum ether/EtOAc 17:3). dH (300 MHz) 0.024 [6 H,
s, (CH3)2], 0.93 [9 H, s, (CH3)3], 1.09 (3 H, t, J = 7.5, CH3),
2.46 (2 H, qd, J = 7.5, 1.5, CH2), 3.75 (3 H, s, OCH3), 3.76
[6 H, s, (OCH3)2], 3.88 (3 H, s, OCH3), 6.30 (1 H, d, J = 1.5,
olefinic H), 6.38 (2 H, s, H-2′,6′), 6.51 (1 H, d, J = 1.9, H-2″),
6.61 (1 H, dd, J = 8.3, 1.9, H-6″), 6.67 (1 H, d, J = 8.3, H-5″).
m/z (FAB) 458 (M+, 95%), 73 (100%). (Found: (MH)+
459.2564. C26H38O5Si requires (MH)+ 459.2566). Further
elution afforded E stilbene 43 as a colourless oil (392 mg,

540
J.A. Hadfield et al. / European Journal of Medicinal Chemistry 40 (2005) 529–541
25%). Rf 0.29 (petroleum ether/EtOAc 17:3). dH (300 MHz)
0.20 [6 H, s, (CH3)2], 1.03 [9 H, s, (CH3)3], 1.11 (3 H, t,
J = 7.5, CH3), 2.73 (2 H, q, J = 7.5, CH2), 3.85 (3 H, s, OCH3),
3.89 (3 H, s, OCH3), 3.91 [6 H, s, (OCH3)2], 6.57 (1 H, s,
olefinic H), 6.68 (2 H, s, H-2′,6′), 6.84–6.93 (3 H, m,
H-2″,5″,6″); dC (100 MHz) –4.2 (CH3), 13.9 (CH3), 18.8 (C),
24.0 (CH2), 26.2 (CH3), 55.9 (CH3), 56.5 (CH3), 61.4 (CH3),
104.2 (CH), 112.3 (CH), 121.7 (CH), 122.8 (CH), 127.4 (CH),
131.4 (C), 137.7 (C), 139.4 (C), 143.6 (C), 145.1 (C), 150.3
(C), 153.4 (C). m/z (FAB) 458 (M+, 10%), 73 (100%). (Found:
(MH)+ 459.2558. C26H38O5Si requires (MH)+ 459.2566).
the method described for the synthesis of stilbene 35. Follow-
ing flash column chromatography (petroleum ether/EtOAc
9:1) and recrystallisation from EtOAc, Z stilbene 47 was iso-
lated as white needles (45 mg, 10%). M.p. 73–75 °C. Rf 0.46
(petroleum ether/EtOAc 3:1). kmax (MeOH) 273 (e = 14,926).
dH (300 MHz) 2.19 (1 H, d, J = 1.5, CH3), 3.74 [6 H, s,
(OCH3)2], 3.76 (3 H, s, OCH3), 3.88 (3 H, s, OCH3), 6.40
(1 H, d, J = 1.5, olefinic H), 6.42 (2 H, s, H-2′,6′), 6.69 (1 H,
d, J = 8.7, H-3″,5″), 6.93 (1 H, d, J = 8.7, H-2″,6″). dC
(100 MHz) 18.2 (CH3), 55.7 (CH3), 56.4 (CH3), 56.6 (CH3),
103.8 (CH), 114.1 (CH), 127.6 (CH), 130.4 (CH), 130.8 (C),
131.2 (C), 136.3 (C), 140.7 (C), 153.5 (C), 158.6 (C); m/z
(EI+) 314 (M+, 100%). (Found: C, 72.8; H, 6.9. C19H22O4
requires C, 72.6; H, 7.05%). Further elution and recrystalli-
sation from EtOAc afforded E-stilbene 48 as an off white
solid (44 mg, 10%). M.p. 80–82 °C. Rf = 0.41 (petroleum
ether/EtOAc 3:1). kmax (MeOH) 287 (e = 21,822). dH
(300 MHz) 2.28 (1 H, d, J = 1.5, CH3), 3.86 (3 H, s, OCH3),
3.90 (3 H, s, OCH3), 3.94 [6 H, s, (OCH3)2], 6.74 (2 H, s,
H-2′,6′), 6.75 (1 H, d, J = 1.5, olefinic H), 6.94 (1 H, d, J = 8.7,
H-3″,5″), 7.34 (1 H, d, J = 8.7, H-2″,6″). m/z (EI+) 314 (M+,
100%).
5.1.30. Z-3-(3′,4′,5′-Trimethoxyphenyl)-4-(3″-hydroxy-
4″-methoxyphenyl)but-3-ene (44)
Phenolic stilbene 44 was prepared from TBDMS ether 42
(125 mg, 0.273 mmol) by the method used to make phenol
12. Flash column chromatography (petroleum ether/EtOAc
2:1) and recrystallisation from EtOAc afforded Z phenol 44
as a white solid (77 mg, 85%). M.p. 106–108 °C. Rf 0.23
(petroleum ether/EtOAc 2:1). dH (300 MHz) 1.09 (3 H, t,
J = 7.5, CH3), 2.47 (2 H, qd, J = 7.5, 1.1, CH2), 3.77 [6 H, s,
(OCH3)2], 3.83 (3 H, s, OCH3), 3.89 (3 H, s, OCH3), 5.4
(1 H, s, OH), 6.30 (1 H, d, J = 1.1, olefinic H), 6.39 (2 H, s,
H-2′,6′), 6.46 (1 H, dd, J = 8.3, 2.3, H-6″), 6.60 (1 H, d,
J = 2.3, H-2″), 6.61 (1 H, d, J = 8.3, H-5″); dC (100 MHz)
13.4 (CH3), 33.9 (CH2), 56.3 (CH3), 56.5 (CH3), 61.4 (CH3),
106.0 (CH), 110.5 (CH), 115.5 (CH), 121.3 (CH), 124.9 (CH),
131.4 (C), 137.5 (C), 143.7 (C), 145.2 (C), 145.4 (C), 148.8
(C), 153.6 (C). m/z (FAB) 344 (M+, 100%). (Found: (MH)+
345.1710; C, 68.7; H, 7.3. C20H24O5 requires (MH)+
345.1702; C, 68.6; H, 7.3%).
5.2. Biochemistry
The stilbenes were tested for cytotoxicity using the previ-
ously published MTT assay [24]. Cell cycle analysis, mea-
surement of the inhibition of tubulin, the colchicine displace-
ment assays and immunohistochemistry were carried out as
previously published [5].
5.1.31. E-3-(3′,4′,5′-Trimethoxyphenyl)-4-(3″-hydroxy-4″-
methoxyphenyl)but-3-ene (45)
Acknowledgements
Phenol 45 was prepared from TBDMS ether 43 (221 mg,
0.483 mmol) by the method used to make phenol 12. Flash
column chromatography (petroleum ether/EtOAc 2:1) and
recrystallisation from EtOAc afforded E-phenol 45 as a white
solid (104 mg, 65%). M.p. 89–91 °C. Rf 0.18 (petroleum
ether/EtOAc 2:1). dH (300 MHz) 1.10 (3 H, t, J = 7.5, CH3),
2.73 (2 H, qd, J = 7.5, 1.1, CH2), 3.89 (3 H, s, OCH3), 3.92
[6 H, s, (OCH3)2], 3.94 (3 H, s, OCH3), 5.61 (1 H, s, OH),
6.58 (1 H, d, J = 1.1, olefinic H), 6.68 (2 H, s, H-2′,6′), 6.84
(1 H, dd, J = 8.3, 1.9, H-6″), 6.88 (1 H, d, J = 8.3, H-5″), 6.96
(1 H, d, J = 1.9, H-2″). dC (100 MHz) 13.9 (CH3), 24.0 (CH2),
56.4 (CH3), 56.6 (CH3), 61.3 (CH3), 104.2 (CH), 111.0 (CH),
115.2 (CH), 121.1 (CH), 127.3 (CH), 132.1 (C), 137.7 (C),
139.2 (C), 144.0 (C), 145.7 (C), 145.8 (C), 153.5 (C). m/z
(FAB) 344 (M+, 100%). (Found: (MH)+ 345.1702. C19H24O5
requires (MH)+ 345.1702).
Funding from the Association for International Cancer
Research, EPSRC, Astra Zeneca and Cancer Research UK,
the Universities of Salford and Cardiff is gratefully acknowl-
edged. We thank Professor Aggarwal for helpful advice.
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