Carboxy-substituted cinnamides: A novel series of potent, orally active LTB4 receptor antagonists

Article abstract of DOI:10.1021/jm980540v

A series of carboxy-substituted cinnamides were investigated as antagonists of the human cell surface leukotriene B₄ (LTB₄) receptor. Binding was determined through measurement of [³H]-LTB₄ displacement from hum

Full text of DOI:10.1021/jm980540v

164
J . Med. Chem. 1999, 42, 164-172
Ca r boxy-Su bstitu ted Cin n a m id es: A Novel Ser ies of P oten t, Or a lly Active LTB4
Recep tor An ta gon ists
Paul D. Greenspan,* Roger A. Fujimoto, Paul J . Marshall, Anil Raychaudhuri, Kenneth E. Lipson,
Huanghai Zhou, Robert A. Doti, David E. Coppa, Lijuan Zhu, Roberta Pelletier, Susan Uziel-Fusi,
Robert H. J ackson, Michael H. Chin, Bernard L. Kotyuk, and J ohn J . Fitt
Arthritis and Bone Metabolism Research, Novartis Pharmaceuticals Corporation, 556 Morris Avenue,
Summit, New J ersey 07901
Received September 28, 1998
A series of carboxy-substituted cinnamides were investigated as antagonists of the human cell
surface leukotriene B4 (LTB4) receptor. Binding was determined through measurement of [3H]-
LTB4 displacement from human neutrophils. Receptor antagonism was confirmed through a
functional assay, which measures inhibition of Ca2+ release in human neutrophils. Potent
antagonists were discovered through optimization of a random screening hit, a p-(R-
methylbenzyloxy)cinnamide, having low-micromolar activity. Substantial improvement of in
vitro potency was realized by the attachment of a carboxylic acid moiety to the cinnamide
phenyl ring through a flexible tether, leading to identification of compounds with low-nanomolar
potency. Modification of the benzyloxy substituent, either through ortho-substitution on the
benzyloxy phenyl group or through replacement of the ether oxygen with a methylene or sulfur
atom, produced achiral antagonists of equal or greater potency. The most potent compounds
in vitro were assayed for oral activity using the arachidonic acid-induced mouse ear edema
model of inflammation. Several compounds in this series were found to significantly inhibit
edema formation and myeloperoxidase activity in this model up to 17 h after oral administration.
Representatives of this series have been shown to be potent and long-acting orally active
inhibitors of the LTB4 receptor.
Ch a r t 1. Structures of LTB4 Antagonists Previously
Reported by Novartis
In tr od u ction
Leukotriene B4 (LTB4), a product of 5-lipoxygenase-
induced arachidonic acid metabolism, has been shown
to be a potent mediator of the inflammatory process and
has thus been implicated in the progression of a variety
of inflammatory diseases.1 At the cellular level, LTB4
exerts its effect through recruitment and activation of
neutrophils and eosinophils, via binding to a G-protein-
coupled cell-surface receptor.2 More recently, it was
reported that LTB4 can activate the nuclear receptor
PPARR, raising the possibility that it may be involved
in feedback regulation of lipid metabolism.3 Clinically,
elevated levels of LTB4 have been observed in patients
of a number of inflammatory diseases, including rheu-
matoid arthritis,4 ulcerative colitis,5 asthma,6 and chronic
bronchitis.7
A variety of potent, orally active antagonists of the
cell-surface LTB4 receptor have been reported over
recent years.8 Preclinical pharmacology conducted with
these compounds has strengthened the case for LTB4
receptor antagonism as a viable drug discovery target.
Representative antagonists have been found to be
effective in the collagen-induced mouse arthritis model,9
a primate model of inflammatory bowel disease,10 and
a guinea pig model of respiratory inflammation.11
Several of these compounds have been reported to be
undergoing clinical development.
Previously, we reported the discovery of potent LTB4
antagonists, exemplified by the arylamidine CGS 25019C
(1)12 and the phenylcinnamide 2 (Chart 1).13 As part of
our continued effort in this area, we report herein the
identification of a novel carboxyphenylcinnamide series
of potent, orally active antagonists of the human cell-
surface LTB4 receptor.
Ch em istr y
The compounds discussed in this report contain a
cinnamide nucleus, with varying substitution on the
aryl moiety (Table 1). Syntheses of the required cinna-
mides proceeded either through Horner-Emmons cou-
pling of an appropriately substituted methyl ketone or
via Heck olefination of the corresponding aryl bromide.14
In our first series of compounds (Scheme 1), cinnamate
ester 3 was prepared through a Heck coupling with an
aryl bromide generated from the alkylation of p-bro-
mophenol. Compounds with R2 ) Me were prepared
stereospecifically from ethyl crotonate. Hydrolysis of the
10.1021/jm980540v CCC: $18.00 © 1999 American Chemical Society
Published on Web 12/24/1998

Carboxy-Substituted Cinnamides
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1 165
Sch em e 1. Synthesis of 4-Alkoxyphenylcinnamidesa
a
(a) R1Br, K2CO3; (b) ethyl crotonate (R2 ) Me) or ethyl acrylate (R2 ) H), Pd(OAc)2, P(o-tol)3, triethylamine, 80 °C; (c) 1 N NaOH,
MeOH, reflux; (d) (COCl)2, DMF, CH2Cl2; (e) HNR3R4, THF.
Ch a r t 2. Miscellaneous Compounds Prepared Similarly
to Scheme 1
Compounds 23 and 24 were prepared from 2-hydroxy-
phenylacetic acid (Scheme 5). Bromination in alcohol
solvent effected simultaneous esterification, providing
21, which was carried on as before. Enantiomers of 23
were prepared via Mitsunobu alkylation of intermediate
22,18 using either enantiomer of 1-methylbenzyl alcohol
as the nucleophile (Scheme 6). Alkylation is known to
proceed with inversion of stereochemistry at the meth-
ylbenzyl position,18 and ee values for the alkylation,
1
which were determined using H NMR,19 were found
ester and acid chloride formation, followed by coupling
with the appropriate amine, yielded products of type 4.
Dihydrocinnamide 5 (Chart 2) was prepared through Pd/
C-catalyzed hydrogenation of cinnamide 4 (R1 ) Ph(Me)-
CHO, R2 ) H). Synthesis of phenylcinnamide 6 pro-
ceeded through Horner-Emmons coupling of 4-acetylbi-
phenyl with triethyl phosphonoacetate, followed by
amide formation as described in Scheme 1. Benzoic acid
7 was prepared from methyl 5-bromosalicylate, using a
protocol similar to Scheme 1.
Compounds oxygenated in the 3-position of the cin-
namide phenyl ring (Scheme 2) were prepared through
selective alkylation of 3,4-dihydroxyacetophenone, ac-
cording to the reported procedure,15 followed by a second
alkylation with the appropriate alkyl halide. Previous
SAR studies had identified the N,N-diethylamide moiety
as being the optimal amide substitution pattern for in
vitro potency (see Table 1, compounds 4a -e). Therefore,
to improve the efficiency of the syntheses, Horner-
Emmons olefinations were carried out with phospho-
noamide 8. This reaction generally provided a ca. 5:1
ratio of E/ Z isomers (determined by 1H NMR), from
which the desired E isomer could be easily isolated via
chromatography. The X group was then appropriately
modified to provide the desired targets, as indicated in
Scheme 2.
Compounds 14 and 15, which are 3,5- or 2,4-dioxy-
genated (respectively), were also prepared via sequential
alkylation, although mixtures were obtained in the first
alkylation (Chart 3).
Synthesis of phenoxypropionate 13 via an ester
intermediate was complicated by the tendency for these
compounds to undergo retro-Michael elimination during
hydrolysis. For this reason, olefinic 10 (n ) 2, X ) CHd
CH2, R ) Ph(Me)CHO-) was prepared. Oxidative olefin
cleavage, followed by immediate oxidation of the un-
stable aldehyde, yielded the desired product.
to be 93% and 97%, respectively, for the R and S
isomers.
The synthesis of phenylpropionate 27 is shown in
Scheme 7. The carbon side chain was incorporated via
a Claisen rearrangement. Rhodium-catalyzed hydrobo-
ration20 and oxidation provided the desired compound.
Resu lts
In Vitr o Activity. LTB4 receptor binding potency
was determined through the measurement of [3H]LTB4
displacement from human neutrophils (PMNs). Our
early lead compound 4a , identified from random screen-
ing, displayed modest LTB4 receptor binding potency
(see Table 1). Removal of the R-methyl group (4h )
caused a substantial drop in potency. Modification the
amide substitution pattern, through variation of alkyl
chain length or acylation of a cyclic amine (4b-e), also
reduced potency. Replacing the pendant R-methylbenzyl
ether with an isopropyl ether resulted in complete loss
of activity (4i). A tertiary amide was found to be
important, as demonstrated by the drop in potency
observed with secondary amide 4f. Olefin reduction (5)
and removal of the â-methyl group (4g) both resulted
in loss of potency. In addition, compounds 4j and 6,
which incorporated elements of an N-arylcinnamide
series previously reported by our group (exemplified by
compound 2, Chart 1),13 were prepared but found to be
inactive.
A feature common to many potent LTB4 receptor
antagonists is the presence of a carboxylic acid or
carboxylate isostere tethered to a hydrophobic nucleus.8
With this in mind, we set out to incorporate a carboxyl-
ate moiety on the template. Since the benzyloxycinna-
mide template 4a already demonstrated submicromolar
activity, it was hoped that an additional electrostatic
interaction would be sufficient to yield more potent
derivatives. Incorporation of a carboxylic acid group at
the R2 position had no effect on potency (7). However, a
simple hydroxy substituent at this position resulted in
a 2-fold improvement (12). Having determined that
acidic substitution at this position would not interfere
with receptor binding, carboxylate groups were then
tethered to the aromatic ring using the phenol as a
linker, as shown in compounds 11a -20. Compound 11a
was found to be 15-fold more potent than the lead
compound 4a .
To prepare 17, phenol 10 (n ) 0, X ) H, R ) PhCH2)
was converted to aryl triflate 16 and then subjected to
Pd(0)-catalyzed acetylene coupling.16 After acetylene
hydrogenation, the synthesis was completed as de-
scribed previously (Scheme 3).
Sulfide 20 was prepared via methoxy thiol 18. This
intermediate was obtained through thermal rearrange-
ment of a thiocarbamate (Scheme 4).17 The synthesis
was completed as shown.

166 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1
Sch em e 2. Synthesis of Dialkoxyphenylcinnamidesa
Greenspan et al.
a
(a) Li2CO3, DMF, RBr; (b) ethyl bromoacetate, K2CO3, acetone, reflux; (c) 8, NaH, THF, reflux; (d) 1 N NaOH, MeOH; (e)
tetrabutylammonium fluoride, THF; (f) OsO4, NaIO4, THF, H2O; (g) NaClO2, NaH2PO4, 2-methyl-2-butene, t-BuOH, H2O.
Ch a r t 3. Regioisomers of Compound 4
caused a 2-3-fold loss in potency, as observed in 11c.
However, potency could be regained by replacement of
the oxygen in the aryl tether with either a sulfur or a
methylene group (20, 17). It was also observed that
o-halo substitution on the benzylic phenyl ring of the
benzyloxy moiety provided a binding enhancement
similar in magnitude to that observed with the 2-phen-
ylethyl group (11d ,e). This effect was even more pro-
nounced for 2,6-disubstituted benzyl groups (11f,g) and
was found to carry over to compounds with the short-
ened carboxylate tether (24). Replacement of the ben-
zyloxy group with a phenyl ether was ineffective (11i).
As an alternative means of removing chirality, the
methylbenzyloxy group was replaced with a diphenyl-
methoxy substituent. This achiral compound was found
to be reasonably potent (11h ), although lack of activity
in the ear edema model precluded further exploration
of this approach (vide infra).
To confirm that these compounds were indeed an-
tagonists (not agonists) of the LTB4 receptor, several of
the most potent inhibitors were tested in a functional
assay which measures the inhibition of LTB4-induced
Ca2+ release from human PMNs. As can be seen from
Table 1, these compounds are indeed potent receptor
antagonists. To confirm that the compounds were not
inhibiting LTB4 production, compound 11a was tested
for 5-lipoxygenase activity.21 The compound displayed
no enzyme inhibition at 100 µM.
Substantial efforts were then undertaken to define
the binding requirements of this carboxylate. Changes
in the tether length (11b, 13) resulted in reduced
potency. Replacement of the oxygen in the tether with
a methylene group had no effect on in vitro activity (27),
while reducing the tether length to one carbon resulted
in only a modest decrease in potency (23). Moving the
carboxylate attachment point from the 3- to the 2-posi-
tion of the core aromatic ring drastically reduced activity
(15). Relocation of the benzyloxy substituent from the
4- to the 5-position resulted in a modest drop in potency
(14). From this study, it was clearly established that a
one- or two-atom carboxylate tether to the 3-position of
the cinnamide phenyl group was optimal for in vitro
activity.
One obvious point of concern with this series was its
chirality. To determine if a stereochemical binding
preference existed within the series, both enantiomers
of 23 were prepared. Indeed, the S isomer (S)-23 was
found to be substantially more potent than the R isomer
(R)-23. Since the need for an enantiomerically pure
synthesis was viewed as a disadvantage for this series,
attention was turned to modification of the benzyloxy
group, to determine if the chiral center was necessary.
Simple removal of the methyl substituent from 11a
In Vivo Activity. To determine the in vivo potency
of our inhibitors, we utilized the arachidonic acid-
induced mouse ear edema model. In this model, inhibi-
tors were administered orally. After a set time period
(see Table 2), the left ear was treated with an acetone
solution of arachidonic acid. (The right ear was treated
with acetone alone.) After 1 h, punches were taken from

Carboxy-Substituted Cinnamides
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1 167
Sch em e 3. Synthesis of Cinnamide with 4′-Carbon Tethera
a
(a) tert-Butyl bromoacetate, K2CO3, acetone, reflux; (b) 10% Pd/C, H2, EtOH; (c) Tf2O, pyr, CH2Cl2, -30 °C; (d) phenylacetylene, TEA,
(Ph3)2PdCl2, CuI, 60 °C; (e) 8, NaH, THF, reflux; (f) HCl, EtOAc.
Sch em e 4. Synthesis of Sulfur-Tethered Phenylcinnamidesa
a
(a) Me2NCSCl, KOH; (b) 250 °C, neat; (c) HO(CH2)2OH, KOH, H2O; (d) BBr3, CH2Cl2, -78 °C; (e) BnBr, K2CO3, acetone, reflux; (f)
ethyl bromoacetate, K2CO3, acetone, reflux; (g) 8, NaH, THF; (h) 1 N NaOH, MeOH.
Sch em e 5. Synthesis of Phenylacetate Derivativesa
(a) Bu4N+Br3-, ROH; (b) RBr, K2CO3, acetone, reflux; (c) diethyl crotonamide, Pd(OAc)2, P(o-tol)3, triethylamine, 80 °C; (d) 1 N NaOH,
a
MeOH.
Sch em e 6. Synthesis of Optically Enriched 23
Sch em e 7. Synthesis of Phenylpropionate Derivativesa
a
(a) Allyl bromide, K2CO3, acetone, reflux; (b) 230 °C; (c) K2CO3, Ph(Me)CHBr, acetone, reflux; (d) 8, NaH, THF, reflux; (e) catecholborane,
Wilkinson cat., THF, 0 °C; (f) (COCl)2, DMSO, -78 °C; (g) NaClO2, 2-methyl-2-butene, Na2HPO4, t-BuOH, H2O.
both ears, and they were measured for myeloperoxidase
(MPO) activity (a marker of neutrophil influx and
activation) and punch weight (edema). Results are
shown in Table 2. In general, inhibition of both mea-
surements was dose-dependent, although a maximal
inhibition of 60-70% was normally observed for both
parameters. The reason for this plateau effect is not
known, although one might surmise that other arachi-
donic acid metabolites might be responsible for the
remainder of the observed inflammatory response. As
an initial study, compounds were dosed 0.5 h prior to
arachidonic acid challenge. At this time point, 11a was
found to be extremely potent in vivo, demonstrating
significant inhibition at doses as low as 0.1 mg/kg.
Indeed, this compound was the most potent compound
tested in this model at this time point, with several
other compounds showing appreciable activity at 1 mg/
kg. To gauge the duration of action of these compounds,
animals were dosed 17 h prior to arachidonic acid
challenge. Under these conditions, 11a displayed only
modest inhibition even at 10 mg/kg. On the other hand,
compounds with an altered carboxylate tether (23, 13)
and 2,6-difluorobenzyloxy substitution (11g) were found
to have excellent duration of action, demonstrating good
inhibition at the 17-h time point, despite lower inhibi-
tion levels than 11a at the shorter time point. The best
potency at the longer time point was observed with 2,6-
difluorobenzyloxy-substituted cinnamide 24, for which
excellent inhibition was observed at doses as low as 3
mg/kg. This result indicates that 24 maintains a level
of potency at 18 h virtually identical to that observed
at the 0.5-h time point. As a general trend, it appears

168 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1
Greenspan et al.
Ta ble 1. Substituted Cinnamides and Their Antagonism of the LTB4 Receptor
a
compd
R1
R2
R3
R4
-(CH2)5-
R5
Et
LTB4 IC50
Ca2+ inhibn Kib
4a
4b
4c
4d
4e
4f
4g
4h
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
PhCH2O-
H
H
H
H
H
H
H
H
H
H
H
H
Me
Me
Me
Me
Me
Me
H
Et
744 ( 27
5800c
i-Pr
Me
n-Pr
Et
Et
Et
i-Pr
Me
n-Pr
H
Et
Et
Et
H
1100c
2100 ( 43
1400 ( 60
2000 ( 43
1600c
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
7900 ( 900
>10000c
>10000
4300c
4i
i-PrO-
Et
4j
Ph(Me)CHO-
Ph(Me)CHO-
Ph-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
PhCH2O-
(2-ClPh)CH2O-
(2-FPh)CH2O-
(2,6-di-ClPh)CH2O-
(2,6-di-FPh)CH2O-
Ph2CHO-
2-(MeO)-5-(CO2H)Ph
5d
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
Et
6
7
>10000c
884 ( 54
50 ( 2
216 ( 18
182 ( 6
67c
COOH
11a
11b
11c
11d
11e
11f
11g
11h
11i
12
OCH2COOH
O(CH2)3COOH
OCH2COOH
OCH2COOH
OCH2COOH
OCH2COOH
OCH2COOH
OCH2COOH
OCH2COOH
OH
O(CH2)2COOH
OCH2CO2H
OCH2CO2H
OCH2COOH
OCH2COOH
CH2COOH
CH2COOH
CH2COOH
CH2COOH
CH2CH2COOH
9.1
82
16
27
14
18
5.2
119c
31 ( 4
56 ( 6
64 ( 4
2400c
PhO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
Ph(Me)CHO-
PhCH2CH2-
PhCH2S-
Ph(Me)CHO-
(S)-Ph(Me)CHO-
(R)- Ph(Me)CHO-
(2,6-di-FPh)CH2O-
Ph(Me)CHO-
420 ( 32
128 ( 7
84 ( 4
2225 ( 819
56 ( 9
34 ( 6
81 ( 4
39 ( 9
536 ( 22
87c
13
81
11.2
14e
15f
17
7.7
26
9.5
20
23
(S)-23
(R)-23
24
22
9.5
27
48 ( 3
a
b
Inhibition of [3H]LTB4 binding to human PMNs. IC50’s reported in nM; n ) 3 except where stated. Inhibition of Ca2+ release from
human PMNs. Ki’s reported in nM; n ) 1 for all compounds. c n ) 1 for this compound. Dihydrocinnamide. e Ph(Me)CHO substituent at
d
5-position of aryl ring. f OCH2CO2H substituent at 2-positon of aryl ring.
Ta ble 2. Inhibition of Arachidonic Acid (AA)-Induced Ear Edemaa
dosing 0.5 h prior to AA challenge
1 mg/kg
dosing 17 h prior to AA challenge
compd
0.1 mg/kg
3 mg/kg
3 mg/kg
10 mg/kg
11a
13
23
11g
24
11d
11e
11f
11h
20
41**/49**
21/15
nt
nt
nt
nt
nt
nt
nt
50**/67**
24**/24*
41**/41**
26**/32**
32*/38**
nt
nt
nt
56**/71**
39**/58**
nt
27/31*
40**/55**
55**/55**
46**/54**
59**/67**
33**/2
19/30*
0/0
25*/12
29*/26
34*15
44**/53**
nt
52**58**
45**/53**
nt
nt
nt
nt
nt
nt
nt
14/0
nt
nt
nt
nt
nt
nt
1/1
27/0
nt
nt
17
a
Compounds were dosed orally to mice in suspension. One ear was then challenged with AA. Animals were sacrificed 2 h after AA
challenge. Values are percent inhibition relative to control ear (reported as punch wt/MPO activity). nt, not tested; *p < 0.05; **p < 0.01.
that many of the more lipophilic compounds, even those
with good in vitro potency, displayed only minimal in
vivo activity. Examples of these compounds include
11d ,f,h , 17, and 20, which all either possess additional
hydrophobic substituents on the pendent phenyl ring
or have the oxygen of the phenyl ring replaced with a
sulfur or methylene group.22 The 2,6-difluorobenzyloxy
group found in 11g and 24 appears to be the optimal
substituent in terms of balancing in vivo and in vitro
potency. The lack of in vivo potency for the monofluoro
compound 11e may be due to its lower in vitro potency.
Con clu sion
Reported herein is a novel series of LTB4 receptor
antagonists. Although initial members of the series were
found to have only moderate potency, identification of
a site for carboxylate binding resulted in preparation
of nanomolar antagonists. The compounds containing
the chiral 1-phenylethoxy substituent exhibited enan-
tiomeric binding selectivities, with the S isomer some
12-fold more potent than the R isomer. In addition,
potent achiral antagonists were also identified, either

Carboxy-Substituted Cinnamides
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1 169
determined by subtracting the weight of the left ear punch
from that of the right ear. As the marker for neutrophil
infiltration, myeloperoxidase activity was measured.28 The
right ear punches from the both the vehicle- and compound-
treated groups were used. The percentage of inhibition was
calculated by comparing the myeloperoxidase activity of the
compound-treated groups with those of the vehicle-treated
group. Statistical significance was determined using a 2-tail
T-test.
by replacement of the oxygen in the phenyl tether with
a carbon or sulfur atom or by ortho-substitution on the
benzylic aromatic ring. Subsequent in vivo studies led
to the discovery of several members of this series which
possess excellent oral activity as long as 17 h after
dosing.
Exp er im en ta l Section
Ch em istr y. Melting points (mp) were determined on either
a Thomas-Hoover or a Mel-Temp II melting point apparatus
and are uncorrected. 1H NMR spectra were recorded on either
a Bruker AC-250, a Bruker AC-300, or a Bruker AC-400
spectrometer using CDCl3 or DMSO-d6 as internal standard.
Chemical ionization MS (CI) were perfomed on an HP 5985
mass spectrometer, using CH4 as the reagent gas. Microanaly-
ses were performed at Robertson Laboratory, Inc., Madison,
NJ . All organic solvents used were of anhydrous grade. All
reactions were run under a positive pressure of nitrogen unless
otherwise stated. Chromatographic separations were per-
formed with silica gel 60. Compounds were dried by suspension
of anhydrous MgSO4, followed by vacuum filtration.
P r ep a r a tion of Com p ou n d for in Vitr o An a lysis. Iden-
tical procedures were used to prepare and dilute compounds
for all in vitro studies. LTB4 was purchased as a solution in
either ethanol or dimethyl sulfoxide (DMSO) (Biomol, Ply-
mouth Meeting, PA) and diluted into Hank’s balanced salt
solution (HBSS) before use. Test compounds were dissolved
in DMSO to produce stock solution of 10 mM. Dilutions were
made so that the final concentration of DMSO was 0.35%.
An t a gon ism of [3H ]LTB4 Bin d in g t o In t a ct H u m a n
Neu tr op h ils. Neutrophils were prepared from citrated venous
blood. Blood (25 mL) was mixed with HESPAN (15 mL)
(DuPont, Wilmington, DE) and allowed to stand at room
temperature for 40 min. The supernatant was removed and
centrifuged for 10 min at 400g. The resulting pellet was
resuspended in phosphate-buffered saline without calcium and
magnesium (GIBCO, Grand Island, NY); 35 mL of the resus-
pended cells was layered over 15 mL of Ficoll-Paque (Sigma,
St. Louis, MO) and then centrifuged for 15 min at 420g. The
resulting cell pellet was resuspended in 10 mL of phosphate-
buffered saline without calcium and magnesium; 25 mL of
deionized water was added to the suspension for 20 s followed
by the same volume of buffer at twice the normal concentra-
tion. The suspension was centrifuged for 5 min at 200g, and
the pellet resuspended in HBSS.
Binding of [3H]LTB4 to neutrophils was measured as
described previously.23,24 Intact human neutrophils (3 × 106)
were added to HBSS containing 0.5 nM [3H]LTB4 (specific
activity 32 Ci/mmol; DuPont-NEN, Boston, MA) and compound
(final volume 0.5 mL). After incubating for 20 min at 0 °C,
the bound radioactivity was collected on Whatman GF/C filters
by vacuum filtration using a Brandel harvester. The filters
were washed twice with ice-cold HBSS. Filters were counted
using Formula-989 scintillation cocktail (DuPont-NEN, Bos-
ton, MA). Nonspecific binding was determined in the presence
of 300 nM LTB4 (Biomol, Plymouth Meeting, PA).
In h ibition of th e LTB4-In d u ced In tr a cellu la r Ca lciu m
Rise in Hu m a n Neu tr op h ils. Increases in intracellular Ca2+
were measured as described previously.25 Neutrophils were
purified from citrated human venous blood by sedimentation
in HESPAN as described above. Neutrophils were isolated
from the resulting pellet by centrifugal elutriation.26 The
neutrophils (2 × 106/mL) were incubated with acetoxymethyl
ester of Fura-2 (0.2 µM) (Molecular Probes Inc.) for 30 min at
37 °C in HEPES-buffered Hank’s solution containing Ca2+ and
Mg2+. The Fura-2-loaded cells were washed and stored on ice
at a concentration of 2 × 106 cells/mL in 10 mM HEPES-
buffered HBSS without Ca2+ and Mg2+. Fifteen minutes before
assay, 1.5 mL of the cell suspension was mixed with 10 µL of
0.15 M Ca2+ and 0.15 M Mg2+ by stirring at 37 °C. Compounds
were added 40 s before the addition of 1 nM LTB4. The change
in fluorescence was followed using a DMX 1000 spectrofluo-
rometer (SLM-Aminco Instruments, Urbana, IL). The Ki was
Compounds 4a -j were prepared using the same synthetic
sequence. Compound 4h is representative.
(R,S)-(E)-Eth yl 3-(4-Ben zyloxyph en yl)-2-bu ten oate (3h ).
To a solution of p-bromophenol (9.51 g, 55 mmol) and benzyl
bromide (5.95 mL, 50 mmol) in acetone (250 mL) was added
K2CO3, and the mixture was heated overnight to reflux. After
cooling, the solvent was evaporated, and the residue was
dissolved in ethyl acetate (EtOAc) (400 mL), washed with
NaOH (1 N, 3 × 200 mL) and brine (200 mL), dried,
evaporated, chromatographed (10% EtOAc/hexane) to yield
1
1-benzyloxy-4-bromobenzene as a clear oil (12.12 g). H NMR
(CDCl3, 250 MHz): δ 7.45 (7H, m); 6.83 (2H, d, J ) 8.1 Hz);
5.01 (s, 2H). A 5.26-g portion of this compound (20 mmol) was
taken up in triethylamine (12 mL), and ethyl crotonate (5.0
mL, 40 mmol) was added to the solution. After the mixture
was purged with nitrogen for 5 min, tri-o-tolylphosphine ((o-
tol)3P) (0.61 g, 2.0 mmol) and palladium acetate (Pd(OAc)2)
(224 mg, 1.0 mmol) were added, the mixture was deoxygenated
for another 5 min, and then the tube was sealed and heated
to 100 °C for 5 h. The mixture was then cooled to room
temperature, diluted with EtOAc (300 mL), and filtered
through Celite. The filtrate was then washed with 1 N HCl (2
× 200 mL) and brine (100 mL), dried, evaporated, and
chromatographed (5% EtOAc/hexane, then 7% EtOAc/hexane)
to yield 3h (2.15 g, 30% for 2 steps) as a white solid, mp 67-
1
68 °C. H NMR (CDCl3, 400 MHz): δ 7.32-7.53 (7H, m); 7.47
(2H, d, J ) 8.1 Hz); 6.11 (1H, s); 5.09 (2H, s); 4.20 (1H, q, J )
7.2 Hz); 1.58 (3H, s); 1.32 (3H, t, J ) 7.2 Hz).
(R,S)-(E)-Dieth yl 3-(4-Ben zyloxyp h en yl)-2-bu ten a m id e
(4a ). To a solution of 3a (1.6 g, 5.4 mmol) in methanol (MeOH)
(30 mL) and tetrahydrofuran (THF) (50 mL) was added 1 N
NaOH (21.6 mL), and the solution was stirred at room
temperature for 1 h. The organic solvents were evaporated,
and the aqueous residue was acidified with 1 N HCl (150 mL)
and extracted with EtOAc (2 × 80 mL). The combined organic
layers were washed with brine, dried, and evaporated. The
residue was then dissolved in methylene chloride (CH2Cl2) (90
mL). The solution was cooled to 0 °C, and N,N-dimethyl-
formamide (DMF) (50 µL) followed by oxalyl chloride (1.7 mL,
19.4 mmol) were then added. The mixture was then warmed
to room temperature over 30 min. Evaporation yielded 1.4 g
of a yellow solid, of which 0.7 g (ca. 2.44 mmol) was dissolved
in THF (50 mL), followed by addition of diethylamine (1.01
mL, 9.77 mmol). The now cloudy mixture was stirred at room
temperature for 2 h, during which time a white precipitate
formed. The solvent was evaporated, and the residue was
dissolved in EtOAc (100 mL), washed with 1 N HCl (2 × 200
mL) and brine, dried, evaporated, and chromatographed (35%
EtOAc/hexane) to yield 4a as a white solid (0.62 g, 71%), mp
determined assuming simple competitive inhibition: Ki ) IC50
(1 + [LTB4]/EC50 of LTB4).
/
In h ibition of Mou se Ea r In fla m m a tion . The methodol-
ogy used was essentially that described previously.27 Female
mice (A/J , J ackson Labs., Bar Harbor, ME) weighing 20 g were
divided into groups consisting of six mice per treatment group.
They were fasted overnight. Compounds were orally admin-
istered a set time before the application of arachidonic acid
using 3% fortified cornstarch, 5% poly(ethylene glycol) 400,
and 0.34% Tween 80 as the vehicle. Arachidonic acid (2 mg in
15 µL of acetone) (Sigma, St. Louis, MO) was applied to the
inner surface of the right ear. The left ear received 15 µL of
acetone. The animals were sacrificed 1 h later. Edema was
1
39-40 °C. H NMR (CDCl3, 400 MHz): δ 7.28-7.48 (7H, m);
6.96 (2H, d, J ) 8.1 Hz); 6.24 (1H, s); 5.09 (2H, s); 3.47 (2H, q,

170 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1
Greenspan et al.
J ) 7.3 Hz); 3.38 (2H, q, J ) 7.4 Hz); 2.29 (3H, s); 1.17 (6H, q,
J ) 7.4 Hz). MS (CI): m/z 324 (M + H). Anal. (C21H25NO2) C,
H, N.
NMR (CDCl3, 400 MHz): δ 7.25-7.40 (5H, m); 7.04 (1H, d, J
) 3.5 Hz); 6.78 (1H, dd, J ) 9.7, 3.5 Hz); 6.65 (1H, d, J ) 9.7
Hz); 6.19 (1H, s); 5.77 (1H, s); 5.33 (1H, q, J ) 8.6 Hz); 3.43
(2H, q, J ) 7.4 Hz); 3.37 (2H, q, J ) 7.4 Hz); 2.21 (3H, s); 1.68
(3H, d, J ) 8.6 Hz); 1.07-1.23 (6H, m). MS (CI): m/z 354 (M
+ H). Anal. (C24H29N5O3) H, N; C: calcd, 74.76; found, 74.10.
Intermediates of type 10 were all prepared using the same
general protocol. The following compound is provided as an
example.
(E)-3-[5-(2-Dieth ylca r ba m oyl-1-m eth ylvin yl)-2-(2,6-d i-
flu or oben zyloxy)p h en oxy]p r op ion ic Acid (13). To a solu-
tion of 10 (R ) Ph(Me)CH-, X ) CHdCH2, n ) 2) (1.7 g, 4.35
mmol) in THF/water (100 mL:100 mL) was added OsO4
solution (4% solution in water, 2.42 mL, 0.22 mmol). After 10
min, sodium periodate (4.65 g, 21.74 mmol) was added, and
the resulting mixture was stirred at room temperature for 5
h. The organic layer was separated, and the aqueous layer was
washed with EtOAc (50 mL). The combined organic layers
were washed with brine, dried, and evaporated. The resulting
residue was taken up in tert-butyl alcohol (60 mL), and 2.0 M
2-methyl-2-butene in THF (26 mL, 52.2 mmol) was added to
the solution. A freshly made solution of sodium chlorite (1.17
g, 13.05 mmol) and sodium dihyodrogen phosphate (1.44 g,
10.44 mmol) in water (12 mL) was then added. The reaction
mixture was stirred at room temperature for 6 h, after which
time it was diluted with 1 N NaOH (50 mL), extracted with
diethyl ether, dried, and evaporated. The product was chro-
matographed (75% EtOAc/hexane, 0.7% AcOH) to yield 13 as
3′-Hyd r oxy-4′-(2,6-d iflu or oben zyloxy)a cetop h en on e (9,
R ) 2,6-d iflu or oben zyl). A mixture of 3′,4′-dihydroxyac-
etophenone (25.0 g, 164.3 mmol), lithium carbonate (12.1 g,
164.3 mmol), and R-bromo-2,6-difluorotoluene (34.0 g, 164.3
mmol) in DMF (400 mL) was stirred at room temperature for
2 days. The mixture was then filtered through Celite, and the
filtrate was evaporated. The residue was diluted with water
(200 mL), and the mixture was filtered. The collected solid was
recrystallized from ethanol to give 9 (R ) 2,6-difluorobenzyl)
1
(17.9 g, 38%). H NMR (DMSO-d6, 250 MHz): δ 9.46 (1H, br
s); 7.10-7.56 (6H, m); 5.16 (2H, s); 2.50 (6H, s).
(E)-[5-(2-Diet h ylca r b a m oyl-1-m et h ylvin yl)-2-(2,6-d i-
flu or oben zyloxy)p h en oxy]a ceta te (10, R ) 2,6-d iflu o-
r oben zyl, X ) COOEt, n ) 1). A mixture of 9 (R )
2,6-difluorobenzyl) (15.0 g, 53.96 mmol), ethyl bromoacetate
(7.2 mL, 64.75 mmol), and K2CO3 (14.9 g, 107.92 mmol) in
acetone (350 mL) was heated to reflux for 18 h. After cooling,
the mixture was filtered, and the filtrate was concentrated in
vacuo. Recrystallization from EtOAc yielded ethyl [5-acetyl-
2-(2,6-difluorobenzyloxy)phenoxy]acetate (13.35 g, 68%). To a
solution of diethyl [2-(diethylamino)-2-oxoethyl]phosphonate
(8)29 (6.9 g, 27.45 mmol) in THF (150 mL) was added sodium
hydride (1.1 g, 27.45 mmol, 60% in mineral oil) in one portion.
The solution was then stirred at room temperature until it
became clear. A solution of the product from the previous step
(8.0 g, 21.96 mmol) in THF (50 mL) was added, and the
mixture was heated to reflux for 18 h. After cooling, the
mixture was then quenched with saturated aqueous am-
monium chloride (50 mL) and extracted with EtOAc (2 × 150
mL). The combined organic phase was washed with water (1
× 100 mL) and brine (1 × 100 mL), dried, evaporated, and
chromatographed (diethyl ether), providing a ca. 7:1 ratio of
E/ Z isomers of the product. Recrystallization from diethyl
ether provided 10 (R ) 2,6-difluorobenzyl, X ) COOEt, n ) 1)
(2.11 g, 20%), mp 73-76 °C. 1H NMR (CDCl3, 250 MHz): δ
6.90-7.42 (6H, m); 6.20 (1H, s); 5.19 (2H, s); 4.65 (2H, s); 4.17
(2H, q, J ) 7.1 Hz); 3.47 (2H, q, J ) 7.4 Hz); 3.38 (2H, q, J )
7.4 Hz); 2.25 (3H, s); 1.26 (3H, t, J ) 7.1 Hz); 1.18 (3H, t, J )
7.4 Hz); 1.15 (3H, t, J ) 7.4 Hz).
1
a white solid (160 mg, 8.6%). H NMR (CDCl3, 300 MHz): δ
7.16-7.38 (5H, m); 7.02 (1H, d, J ) 2.2 Hz); 7.85 (1H, dd, J )
8.5, 2.2 Hz); 6.68 (1H, d, J ) 8.5 Hz); 6.16 (1H, d, J ) 1.1 Hz);
5.23 (1, q, J ) 7.2 Hz); 4.31 (1H, t, J ) 6.4 Hz); 3.26-3.50
(4H, m); 2.86 (2H, t, J ) 6.3 Hz); 2.17 (3H, d, J ) 1.1 Hz);
1.62 (3H, d, J ) 7.2 Hz); 1.05-1.21 (6H, m). MS (CI): m/z 426
(M + H). Anal. (C25H31NO5) C, H, N.
ter t-Bu tyl {5-Acetyl-2-[(tr iflu or om eth yl)su lfon yloxy]-
p h en oxy}a ceta te (16). To a solution of 10 (X ) CO2t-Bu, R
) Bn, n ) 1) (2.0 g, 5.6 mmol) in EtOH (25 mL) was added
10% Pd/C (0.10 g), and the mixture was hydrogenated at 1
atm for 1.25 h. The solution was filtered, evaporated, and
dissolved in CH2Cl2. To this solution at -30 °C was added
pyridine (1.2 mL, 15.0 mmol), followed by triflic anhydride (1.5
g, 5.6 mmol) via syringe over 2 min. After stirring 10 min,
water (20 mL) was added; the solution was warmed to room
temperature, washed with 1 N HCl (1 × 50 mL) and brine (1
× 50 mL), dried, and concentrated in vacuo. The residue was
chromatographed (silica, 15% EtOAc/hexane) to yield 16 (1.3
1
g, 60% for 2 steps). H NMR (CDCl3, 300 MHz): δ 7.61 (1H,
dd, J ) 9.5, 1.2 Hz); 7.52 (1H, d, J ) 1.2 Hz); 7.35 (1H, d, J )
Compounds of type 11 were all prepared from their precur-
sors 10 using the same protocol. Compound 11g is representa-
tive.
9.5 Hz); 7.27 (1H, s); 4.66 (2H, s); 2.0.53 (3H, s); 1.49 (9H, s).
(R,S)-(E)-[5-(2-Dieth ylcar bam oyl-1-m eth ylvin yl)-2-ph en -
eth ylp h en oxy]a cetic Acid (17). A solution of 16 (0.50 g, 1.3
mmol) and phenylacetylene (0.33 mL, 3.0 mmol) in 20 mL of
triethylamine in a thick walled Pyrex tube was degassed with
nitrogen for 15 min. Bis(triphenylphosphine)palladium(II)
chloride (35 mg, 0.05 mmol) and copper(I) iodide (10 mg, 0.05
mmol) were added, and the vessel was sealed and heated to
60 °C for 18 h. After cooling, the triethylamine was removed
in vacuo, and the residue was dissolved in diethyl ether (100
mL), washed with 1 N HCl (1 × 100 mL) and brine (1 × 50
mL), dried, and evaporated. The product was chromatographed
(15% EtOAc/hexane), dissolved in 5 mL of THF, and diluted
with ethanol (15 mL). 10% Palladium on activated carbon (0.10
g) was added, and the mixture was hydrogenated at 1 atm
until the theoretical amount of hydrogen was consumed.
Filtration through Celite, followed by solvent removal in vacuo,
yielded tert-butyl (E)-(5-acetyl-2-phenethylphenoxy)acetate
(E)-[5-(2-Diet h ylca r b a m oyl-1-m et h ylvin yl)-2-(2,6-d i-
flu or oben zyloxy)p h en oxy]a cetic Acid (11g). To a solution
of 10 (R ) 2,6-difluorobenzyl, X ) COOEt, n ) 1) (2.1 g, 4.55
mmol) in methanol (30 mL) was added 1 N NaOH (13.7 mL,
13.7 mmol), and the mixture was stirred at room temperature
for 2 h. The solution was then acidified to pH 1 with 1 N HCl,
and the mixture was extracted with EtOAc (2 × 100 mL). The
combined organic phase was washed with water (1 × 100 mL)
and brine (1 × 100 mL), dried, and evaporated. The resulting
solid was triturated from diethyl ether, giving 11g (1.94 g,
98%), mp 120-122 °C. 1H NMR (DMSO-d6, 250 MHz): δ 6.90-
7.42 (6H, m); 6.20 (s, 1H); 5.21 (2H, s); 4.65 (2H, s); 3.50 (2H,
q, J ) 7.4 Hz); 3.40 (2H, q, J ) 7.4 Hz); 2.25 (3H, s); 1.21 (3H,
t, J ) 7.4 Hz); 1.18 (3H, t, J ) 7.4 Hz). Anal. (C23H25F2N2O5)
C, H, N.
1
(R,S)-(E)-Dieth yl 3-(3-Hyd r oxy-4-ben zyloxyp h en yl)-2-
bu ten a m id e (12). To 10 (n ) 0, R ) Ph(Me)CHO, X ) TMS)
(0.93 g, 2.05 mmol) in THF (40 mL) at 0 °C was added 1 M
tetrabutylammonium fluoride (TBAF) in THF (2.25 mL, 2.25
mmol) slowly, via syringe. The solution was then warmed to
room temperature over 1.5 h. The solution was quenched with
1 N HCl (20 mL), and THF was evaporated. The residue was
dissolved in EtOAc (100 mL), washed with water and brine,
dried, and evaporated. The residue was chromatographed (45%
EtOAc/hexane) to yield 12 as a thick oil (0.353 g, 50%). 1H
(0.20 g, 43%). H NMR (CDCl3, 300 MHz): δ 7.14-7.41 (6H,
m); 6.78 (2H, s); 4.61 (2H, s); 2.53 (3H, s); 1.50 (9H, s). This
material was then subjected to Horner-Emmons olefination
as described for 10, directly affording 17 after chromatography
(5% MeOH/CH2Cl2) as a clear oil (0.14 g, 63%). 1H NMR
(CDCl3, 300 MHz): δ 7.13-7.42 (5H, m); 7.09 (d, 1H, J ) 8.0
Hz); 6.94 (1H, d, J ) 8.0 Hz); 6.83 (1H, s); 6.23 (1H, s); 4.65
(2H, s); 3.50 (2H, q, J ) 7.2 Hz); 3.38 (2H. q, J ) 7.2 Hz);
2.70-3.15 (4H, m); 2.19 (3H, s); 1.10-1.31 (6H, m). MS: m/z
396 (M + H). Anal. (C24H29NO4‚H2O) C, H, N.

Carboxy-Substituted Cinnamides
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1 171
4′-Mer ca p to-3′-m eth oxya cetop h en on e (18). To a solu-
tion of 3-hydroxy-4-methoxyacetophenone (8.31 g, 50 mmol)
and 2.81 g of potassium hydroxide (50 mmol) in water (34 mL),
at 0 °C, was added a solution of dimethylthiocarbamoyl
chloride (8.28 g, 67 mmol) in THF (14 mL), dropwise, at such
a rate as to keep the reaction temperature below 12 °C. The
reaction mixture was warmed to room temperature and stirred
for 30 min. It was then diluted with 1 N NaOH (100 mL) and
extracted with EtOAc (3 × 80 mL). The combined organic
phase was washed with water (1 × 100 mL) and brine (1 × 50
mL), dried, concentrated in vacuo, and then added to a thick
walled Pyrex tube. The tube was flushed with nitrogen, sealed,
and then heated to 250 °C for 1 h. After cooling, the residue
was chromatographed (silica gel, 50% EtOAc/hexane), and the
product was dissolved in ethylene glycol (50 mL). Potassium
hydroxide (1.0 g, 17.8 mmol) in water (5 mL) was added, and
this mixture was heated to reflux for 1 h. After cooling, this
mixture was poured into 250 mL of ice and then washed with
diethyl ether (3 × 75 mL). The aqueous phase was then
acidified to pH 1 with concentrated HCl, and the solution was
filtered to remove the precipitate. The aqueous layer was then
extracted with EtOAc (3 × 75 mL), and the combined organic
phase was washed with water (1 × 50 mL) and brine (1 × 50
mL), dried, and evaporated to yield 18 (3.59 g, 42% for 3 steps).
1H NMR (CDCl3, 250 MHz): δ 7.42 (1H, s); 7.41 (1H, d, J )
8.1 Hz); 7.28 (1H, d, J ) 8.1 Hz); 3.93 (3H, s); 2.60 (1H, s).
MHz): δ 7.16-7.40 (7H, m); 6.65 (1H, d, J ) 8.2 Hz); 6.17
(1H, s); 5.32 (1H, q, J ) 7.1 Hz); 3.74 (2H, s); 3.47 (q, 2H, J )
7.4 Hz); 3.36 (2H, q, J ) 7.4 Hz); 2.21 (3H, s); 1.60 (3H, d, J )
7.1 Hz); 1.20 (3H, t, J ) 7.4 Hz); 1.14 (3H, t, J ) 7.4 Hz). MS
(CI): m/z 396 (M + H). Anal. (C24H29NO4) C, H, N.
(R)-Meth yl [5-Br om o-2-(1-p h en yleth oxy)p h en yl]a ce-
ta te ((R)-25). To a solution of 22 (1.0 g, 4.1 mmol), (S)-(-)-
phenethyl alcohol (0.49 mL, 4.1 mmol), and triphenylphos-
phine (1.07 g, 4.1 mmol) in toluene (15 mL) at 0 °C was added
diethyl azodicarboxylate (0.64 mL, 4.1 mmol) in toluene (5 mL),
dropwise, over 15 min, and the solution was warmed to room
temperature overnight. The solution was then diluted with 20
mL of toluene, stirred with 10 g of bentonite, filtered, evapo-
rated, and chormatographed to yield (R)-25. 1H NMR (CDCl3,
250 MHz): δ 7.09-7.39 (7H, m); 6.51 (1H, d, J ) 7.2 Hz); 5.23
(1H, q, J ) 6.3 Hz); 3.78 (3H, s); 3.62 (2H, s); 1.57 (3H, d, J )
6.3 Hz).
(R)-(E)-[5-(2-Dieth ylca r ba m oyl-1-m eth ylvin yl)-2-((R)-
1-p h en ylet h oxy)p h en yl]a cet ic Acid ((R)-23). Compound
(R)-25 was carried on to product using the same protocol as
described for compound 23 to provide (R)-23. Optical purity
was determined via 1H NMR analysis of a solution of (R)-23
(11 mg) with (R)-naphthylethylamine (6.7 µL) in 0.5 mL of
CDCl3. This solution produced a doubling of most 1H signals
when racemic 23 was used. With (R)-23, comparison of signal
intensities for methyl singlets at δ 2.15 and 2.17 gave an ee of
97%.
(S)-(E)-[5-(2-Dieth ylca r ba m oyl-1-m eth ylvin yl)-2-((S)-1-
p h en yleth oxy)p h en yl]a cetic Acid ((S)-23). (S)-23 was
prepared exactly as was (R)-23, except that (R)-(-)-phenethyl
alcohol was employed in the Mitsunobu reaction. Optical
purity determination as described above gave an ee of 93%.
3′-Allyl-4′-(1-p h en yleth oxy)a cetop h en on e (26). A solu-
tion of 4-hydroxyacetophenone (9.53 g, 70 mmol), allyl bromide
(6.66 mL, 77 mmol), and K2CO3 (14.51 g, 105 mmol) in acetone
(150 mL) was heated to reflux for 6 h. The mixture was then
filtered, and the filtrate was concentrated in vacuo. The
residue was dissolved in EtOAc (100 mL), then washed with
water (1 × 100 mL) and brine (1 × 100 mL), dried, and
evaporated. The residue was dissolved in 10 mL of xylene and
was introduced into a thick walled Pyrex tube, which was
sealed with a Teflon cap. After heating to 230 °C for 5 h, the
solution was cooled to 0 °C. The precipitated white solid was
filtered and washed with toluene. Half of this material, along
with 1-bromoethylbenzene (3.05 mL, 21.63 mmol) and K2CO3
(4.07 g, 29.49 mmol), were dissolved in acetone (100 mL) and
heated to reflux for 20 h. The mixture was then filtered, and
the filtrate was concentrated in vacuo. The residue was
dissolved in EtOAc (100 mL), then washed with water (1 ×
100 mL) and brine (1 × 100 mL), dried, and evaporated.
Chromatography (15% EtOAc/hexane) yielded 26 as a clear
oil (4.28 g, 39% for 3 steps). 1H NMR (CDCl3, 250 MHz): δ
7.91 (2H, d, J ) 9.4 Hz); 6.91 (2H, d, J ) 9.4 Hz); 5.95-6.14
(1H, m); 5.41 (1H, dq, J ) 19.4, 1.1 Hz); 5.29 (1H, dq, J )
11.8, 1.1 Hz); 4.58 (2H, dt, J ) 6.8 Hz, 1.1 Hz); 2.52 (3H, s).
(R,S)-(E)-3-[3-(3-H yd r oxyp r op yl)-4-(1-p h en ylet h oxy)-
p h en yl]bu t-2-en a m id e (27). 26 (2.91 g, 10.4 mmol) was
subjected to Horner-Emmons olefinations with phosphonate
8 as described for compound 10. This material was then
dissolved in THF (40 mL), and Wilkinson’s catalyst (64 mg,
0.069 mmol) was added to the solution, followed by a 1.0 M
solution of catecholborane in THF (7.62 mL, 7.62 mmol), via
syringe. After stirring for 3 h at 0 °C, the solution was
quenched with methanol (15 mL), followed by addition of a
solution 30% hydrogen peroxide (1.94 mL) in 3 M NaOH (18
mL). The solution was then warmed to room temperature over
3 h. The solution was concentrated to 25 mL in vacuo, and
the residue was taken up in water (100 mL) and extracted
with diethyl ether (3 × 50 mL). The combined organic phase
was washed with water (1 × 50 mL) and brine (1 × 50 mL),
dried, evaporated, and chromatographed (20% EtOAc/hexane)
to yield 0.25 g of product. A solution of oxalyl chloride (60 µL,
0.696 mmol) in CH2Cl2 (5 mL) was cooled to -78 °C, and
DMSO (98 µL, 1.39 mmol) was added dropwise via syringe.
4′-Ben zylth io-3′-h yd r oxya cetop h en on e (19). To a solu-
tion of 18 (3.59 g, 19.73 mmol) in CH2Cl2 (100 mL) at -78 °C
was added BBr3 (3.73 mL, 39.46 mmol) dropwise via syringe,
and the resulting solution was stirred for 2 h. The solution
was then poured into ice water (300 mL), and the organic layer
was collected and evaporated. The residue was dissolved in
EtOAc (140 mL), washed with water and brine, dried, and
evaporated to yield 2.51 g of crude phenol, of which 0.84 g (ca.
5 mmol) was dissolved in acetone (30 mL). To this solution
were added benzyl bromide (0.60 mL, 5 mmol) and K2CO3 (0.69
g, 5 mmol), and the mixture was heated to reflux for 2 h. After
cooling, the solvent was evaporated, and the residue was
dissolved in EtOAc (400 mL), washed with HCl (1 N, 3 × 200
mL) and brine (200 mL), dried, evaporated, and chromato-
graphed (35% EtOAc/hexane). The lower, minor spot was
1
isolated as 19 (0.38 g, 20% for 2 steps). H NMR (CDCl3, 250
MHz): δ 702-7.43 (8H, m); 6.51 (1H, s); 4.90 (2H, s); 2.04 (3H,
s).
(E)-[5-(2-Diet h ylca r b a m oyl-1-m et h ylvin yl)-2-(1-b en -
zylth io)p h en yl]a cetic Acid (20). Phenol 19 (1.16 g, 4.5
mmol) was carried on as described for compounds 10 and 11
to yield 20 as a white solid, mp 132-134 °C (0.35 g, 19% for 3
steps). 1H NMR (CDCl3, 300 MHz): δ 7.17-7.34 (5H, m); 7.15
(1H, d, J ) 8.0 Hz); 6.91 (1H, dd, J ) 8.0, 1.8 Hz); 6.81 (1H,
d, J ) 1.8 Hz); 6.20 (1H, d, J ) 1.0 Hz); 4.67 (2H, s); 4.11 (2H,
s); 3.45 (1H, q, J ) 7.1 Hz); 3.33 (1H, q, J ) 7.1 Hz); 2.13 (3H,
d, J ) 1.0 Hz); 1.16 (3H, t, J ) 7.1 Hz); 1.13 (3H, t, J ) 7.1
Hz). MS (CI): m/z 414 (M + H). Anal. (C23H27NO4S) C, H, N.
Eth yl (5-Br om o-2-h yd r oxyp h en yl)a ceta te (21). 2′-Hy-
droxyphenylacetic acid (25.0 g, 164 mmol) was dissolved in
ethanol (400 mL). Tetrabutylammonium tribromide (79.23 g,
164 mmol) was added to the solution, and the resulting
mixture was stirred at room temperature for 18 h. After
evaporation of solvent, the residue was dissolved in diethyl
ether (300 mL), washed with 1 N HCl (100 mL), 2 M sodium
bisulfate (50 mL), water (50 mL), and brine (50 mL), dried,
and evaporated to yield 21 (38.25 g, 90%) which was carried
on directly. 1H NMR (CDCl3, 250 MHz): δ 7.75 (1H, br s); 7.28
(1H, d, J ) 1.1 Hz); 7.24 (1H, s); 7.20 (1H, d, J ) 1.1 Hz); 6.82
(1H, d, J ) 7.5 Hz); 4.20 (2H, q, J ) 7.1 Hz); 3.16 (3H, s); 1.30
(3H, t, J ) 7.1 Hz).
(R,S)-(E)-[5-(2-Dieth ylca r ba m oyl-1-m eth ylvin yl)-2-(1-
p h en yleth oxy)p h en yl]a cetic Acid (23). 21 (3.7 g, 14 mmol)
was alkylated with 1-bromoethylbenzene and subjected to
Heck arylation with diethyl crotonamide using the procedure
described for compound 3a . This product was then subjected
to ester hydrolysis as described for compound 11d , yielding
1
23 as a clear oil (1.2 g, 21% for 3 steps). H NMR (CDCl3, 300

172 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 1
Greenspan et al.
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After 5 min, a solution of the product from the previous step
was added to this solution. After 15 min, triethylamine (0.40
mL, 2.85 mmol) was added, and the solution was warmed to
room temperature over 15 min. The mixture was then quenched
with water (50 mL) and extracted with CH2Cl2 (25 mL), and
the organic phase was washed with water and brine, and dried.
This material was then subjected to sodium chlorite oxidation
as described for compound 13 to yield 27 as a thick oil (0.10 g,
3% yield for 3 steps). 1H NMR (CDCl3, 300 MHz): δ 7.20-
7.40 (6H, m); 7.10 (1H, dd, J ) 7.5, 1.1 Hz); 6.62 (1H, d, J )
7.5 Hz); 6.16 (1H, s); 5.81 (1H, q, J ) 7.3 Hz); 3.31-3.47 (4H,
m); 3.04 (t, 2H, J ) 7.7 Hz); 2.75 (2H, t, J ) 7.5 Hz); 2.21 (3H,
s); 1.63 (3H, d, J ) 7.3 Hz); 1.15 (6H, t, J ) 7.3 Hz). MS (CI):
m/z 410 (M+ + H). Anal. (C25H29NO4‚H2O) C, H, N.
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