Indole cytosolic phospholipase A2 α inhibitors: Discovery and in vitro and in vivo characterization of 4-{3-[5-chloro-2-(2-{[(3,4- dichlorobenzyl)sulfonyl]amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl} benzoic acid, efipladib

3388

J. Med. Chem. 2008, 51, 3388–3413

Indole Cytosolic Phospholipase A₂r Inhibitors: Discovery and in Vitro and in Vivo

Characterization of 4-{3-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid, Eﬁpladib

John C. McKew,*^,†Katherine L. Lee,^†Marina W. H. Shen,^‡Paresh Thakker,^†Megan A. Foley,^†Mark L. Behnke,^†Baihua Hu,^†

Fuk-Wah Sum,^†Steve Tam,^†Yonghan Hu,^†Lihren Chen,^†Steven J. Kirincich,^†Ronald Michalak,^#Jennifer Thomason,^†

Manus Ipek,^†Kun Wu,^†Lane Wooder,^†Manjunath K. Ramarao,^‡Elizabeth A. Murphy,^‡Debra G. Goodwin,^‡Leo Albert,^‡

Xin Xu,^§Frances Donahue,^#M. Sherry Ku,^#James Keith,^‡Cheryl L. Nickerson-Nutter,^‡William M. Abraham,

Cara Williams,^‡Martin Hegen,^‡and James D. Clark^‡

Departments of Chemical and Screening Sciences, Inﬂammation, Drug Safety and Metabolism, and Chemical and Pharmaceutical

DeVelopment, Wyeth Research, 200 CambridgePark DriVe, Cambridge, Massachusetts 02140, and Mount Sinai Medical Center,

4300 Alton Road, Miami Beach, Florida 33140

ReceiVed NoVember 21, 2007

The optimization of a class of indole cPLA₂R inhibitors is described herein. The importance of the substituent

at C3 and the substitution pattern of the phenylmethane sulfonamide region are highlighted. Optimization

of these regions led to the discovery of 111 (eﬁpladib) and 121 (WAY-196025), which are shown to be

potent, selective inhibitors of cPLA₂R in a variety of isolated enzyme assays, cell based assays, and rat and

human whole blood assays. The binding of these compounds has been further examined using isothermal

titration calorimetry. Finally, these compounds have shown efﬁcacy when dosed orally in multiple acute

and chronic prostaglandin and leukotriene dependent in vivo models.

Introduction

(COX-2) inhibitors block the conversion of AA to PGs, and

extensive clinical trials have conﬁrmed that PGs are proinﬂam-

matory and potentiate pain.⁴LTB₄contributes to inﬂammation

by both recruiting and activating leukocytes, while cysteinyl

leukotrienes (LTC₄, D₄, and E₄) promote edema by increasing

vascular permeability and permitting leakage of plasma to the

extravascular space.⁵5-Lipoxygenase inhibition and LTD₄

receptor antagonists are both effective in animal models of pain.⁶

Thus, there may be added beneﬁt in inhibiting both PGs and

LTs in the treatment of inﬂammation and pain. PAF receptor

antagonists have not been successful in the clinic, but genetically

altered mice either overexpressing or deﬁcient in the PAF

receptor do support a role for PAF in inﬂammation and pain.^7,8

The arachidonic acid pathway is rich with targets for phar-

maceutical intervention, and as such, selected enzymes and

receptors have been successfully targeted in the past for the

treatment of pain and asthma. New genetic data in humans and

mice have led to renewed interest in additional targets in the

arachidonic acid pathway with potential to deliver safer chronic

therapies and to expand into treatment of cardiovascular disease.

The pathway is of interest because metabolism of arachidonic

acid (AA^a) produces multiple mediators of inﬂammation includ-

ing prostaglandins (PGs), thromboxanes (TXs) and leukotrienes

(LTs). Platelet activating factor (PAF), another inﬂammatory

mediator, can be formed from the lysophospholipid that is

produced in the cleavage of membrane phospholipids by

cPLA₂R to release AA.^1–3Each of these mediators has been

implicated in a variety of disease states. Nonsteroidal anti-

inﬂammatory drugs (NSAIDs) and selective cyclooxygenase-2

The key step in the biosynthesis of each of these potent

mediators is the selective release of AA from glycerophospho-

lipids. Cytosolic phospholipase A₂R (cPLA₂R, a group IVA

phospholipase) is exceptionally well validated^3,9,10to be the

source of the AA coupled to the synthesis of the above-

mentioned inﬂammatory mediators. The generation of gene

deletion mice^10,11has proven that cPLA₂R plays not only a

central role in the AA pathway but in a broad range of disease

states. These gene deletion mice are generally healthy and are

also resistant to numerous inﬂammatory disease models includ-

ing collagen induced arthritis,¹²ova induced model of anaphy-

laxis,³acid or sepsis induced adult respiratory distress syndrome

(ARDS),¹³reperfusion injury in a model of middle cerebral

artery occlusion,¹⁴MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahy-

dropyridine) induced model of Parkinson’s disease,¹⁵polyp

formation in APC (adenoma polyposis carcinoma) mice^16,17and

are resistant to experimental autoimmune encephalomyelitis

(EAE), a model of human multiple sclerosis.¹⁸Clearly cPLA₂R

represents a target for pharmaceutical intervention with the

potential to yield therapeutics useful in a broad range of disease

states.

* To whom correspondence should be addressed. Phone: 617-665-5603.

Fax: 617-665-5685. E-mail: jmckew@wyeth.com.

†

Department of Chemical and Screening Sciences.

Department of Inﬂammation.

Department of Chemical and Pharmaceutical Development.

Department of Drug Safety and Metabolism.

‡

#

§

Mount Sinai Medical Center.

^aAbbreviations: cPLA₂R, cytosolic phospholipase A₂R; AA, arachidonic

acid; PGs, prostaglandins; TXs, thromboxanes; LTs, leukotrienes; PAF,

platelet activating factor; NSAIDs, nonsteroidal anti-inﬂammatory drugs;

COX-2, cyclooxygenase-2; LTC₄, D₄, and E₄, cysteinyl leukotrienes; ARDS,

adult respiratory distress syndrome; MPTP, 1-methyl-4-phenyl-1,2,3,6-

tetrahydropyridine; APC, adenoma polyposis carcinoma; EAE, experimental

autoimmune encephalomyelitis; GLU, 7-hydroxycoumarinyl-γ-linolenate;

A23187, a calcium ionophore; COX-1, cyclooxygenase-1; 5-LO, 5-lipoxy-

genase; ITC, isothermal titration calorimetry; PAPC, 1-palmitoyl-2-arachi-

donoyl-sn-glycero-3-phosphocholine; PAPE, 1-palmitoyl-2-arachidonoyl-

sn-glycero-3-phosphoethanolamine; sPLA₂, type II secreted phospholipase

A₂; TMPD, N,N,N′,N′-tetramethylbenzene-1,4-diamine; F, oral bioavail-

ability; CPE carrageenan paw edema; CIA, collagen-induced arthritis; AIA,

adjuvant-induced arthritis; AHR, acute hyperresponsiveness; LAR, late

asthmatic response; FT-ICR, Fourier transform ion cyclotron resonance;

ESI, electrospray ionization.

The search for well-behaved cPLA₂R inhibitors began when

the enzyme was ﬁrst characterized nearly 2 decades ago. This

10.1021/jm701467e CCC: $40.75

2008 American Chemical Society

Published on Web 05/23/2008

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3389

Figure 1. Wyeth’s indole cPLA₂R inhibitors.

effort has produced compounds as distinct as electrophilic

ketones,^19–24natural products that inhibit cPLA₂R,^25,26and

compounds that are purported to have dual cPLA₂R and

sPLA₂activity.²⁷Pyrimidone inhibitors from Elan,²⁸dicar-

boxylic acids from the Lehr group,^29–31pyrrolidine-based

inhibitors from Shionogi,^32–34propane-2-ones from Astra

Zeneca,³⁵tricarbonyl inhibitors from the Dennis laboratory,²¹

and the oxamide-based inhibitors from Kokotos^36,37have been

reported. Synthetic inhibitors of phopholipases have been

reviewed recently.^38–40

intraperitoneal and intrathecal administration^46,47but has not

been able to show the broad spectrum of activity one would

expect from a potent cPLA₂R inhibitor.

This report details the optimization of the C3 acid linker and

the nature of the sulfonamide group in the indole based series

of inhibitors shown in Figure 1 and provides data on 111

(eﬁpladib), Wyeth’s second clinical candidate, and 121 (WAY-

196025), a compound undergoing preclinical evaluation. These

two compounds demonstrate increased potency over 2 (Ecop-

ladib),⁴⁴reduced clearance in vivo and efﬁcacy in the broad

range of in vivo models one would expect for compounds that

inhibit cPLA₂R.

cPLA₂R assays are complicated in that cPLA₂R is a soluble

enzyme that cleaves its phospholipid substrate at the membrane/

water interface, and thus, Michaelis–Menten kinetics do not

apply. The initial substrate-binding step includes the binding

of the enzyme to the membrane surface and then the

subsequent binding of an individual phospholipid at the active

site. Therefore, the rate of reaction is dependent on the

equilibrium between membrane-bound and free enzyme,

substrate accessibility and replenishment, and the kinetics

of the catalytic steps. In many assay systems, compounds

interfering with any of these parameters score as inhibitors.

We have validated an assay paradigm⁴¹that relies on a

7-hydroxycoumarinyl-γ-linolenate (GLU) micelle assay that

allows micellar presentation of the inhibitor and substrate to

the enzyme. The high lipid content in this assay selects

against inhibitors that would act as inhibitors by altering the

membrane surface. This assay is followed by a physiologi-

cally relevant rat whole blood assay. Stimulation of rat whole

blood with A23187, a calcium ionophore, reproducibly leads

to production of thomboxane A₂that is downstream of both

cPLA₂R and cyclooxygenase-1 (COX-1). This assay is

stringent in that the blood contains both serum proteins that

can bind and sequester inhibitor and a high lipid content

relative to standard cellular assays. Since NSAIDS, COX-2

inhibitors, and 5-lipoxygenase (5-LO) inhibitors are all active

in whole blood assays at the plasma concentrations observed

in humans at clinical doses,^42,43this assay is critical to the

development of SAR and to the identiﬁcation of compounds

for further characterization. Finally, evidence of direct

binding to target and detailed thermodynamics of binding

can also be generated using isothermal titration calorimetry.⁴⁴

At Wyeth we have used these assays to develop a series of

potent and selective cPLA₂R inhibitors.^41,44,45When repre-

sentatives of many of the classes of inhibitors mentioned

above are tested under these stringent assays used to develop

Wyeth’s inhibitors, they have limited activity.⁴⁴The pyrro-

lidine inhibitor from Shionogi is the only compound to

display activity in a stringent isolated enzyme assay and in

whole blood assays; however, physicochemical properties

limit its activity in vivo. The oxamide described by Kokotos

has been shown to have an antihyperalgesia effect with

Chemistry

The observation⁴¹that more potent cPLA₂R inhibitors could

be achieved by varying the linker between the indole ring and

the benzoic acid suggested a re-examination of this part of the

molecule once the third part of the pharmacophore, the C2

sulfonamide,⁴⁴had been established. The synthetic approach

that was utilized was to build on our earlier synthesis⁴⁴and to

install the C3 portion, and the required diversity, via reductive

alkylation^48,49as the penultimate step. This approach was

successful for a number of analogues resulting from reaction

of both aryl- and alkylaldehydes, as shown in Scheme 1. We

observed side reactions, including loss of the benzhydryl group

under the conditions of the reductive alkylation reaction, as well

as cyclization of the sulfonamide nitrogen onto the intermediate

indolium ion before it could be reduced. The formation of these

undesired byproduct prompted us to explore other routes to vary

the C3 position.

In order to increase the yield and the versatility of the

synthesis, an approach in which the C3 group was installed

earlier in the synthesis and generally gave higher yields was

employed. The C3 group was added at the C2 methyl stage,

(e.g., compound 18 in Scheme 2), and then the C2 methyl

substituent was elaborated to the sulfonamide using previously

established chemistry.⁴⁴This approach provided the all carbon

linked analogue 24.

The installation of the sulfone linker utilized a similar

approach, except the reductive alkylation was performed on the

known C2 alcohol 25⁵⁰as depicted in Scheme 3. The alcohol

was ﬁrst protected as the tBDPS ether, which survived the

conditions used to install the C3 linker. The C2 group was then

elaborated by deprotection to the alcohol, activation as the

mesylate, displacement by azide, reduction to the amine, and

then sulfonylation to produce 35 after hydrolysis of the C3

methyl ester.

Another synthetic approach was used to synthesize C3 linkers

with sulfone propionate functionality. The known alcohol 36,⁴⁴

Scheme 4, was activated as the bromide and then displaced with

3390 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

Scheme 1. Late Stage Introduction of C3 Linker^a

McKew et al.

^a(a) NaH, DMF, BrCH(Ph)₂; (b) CH₃NO₂, NH₄OAc, reﬂux; (c) Zn(Hg) amalgam, HCl, THF; (d) NaHCO₃, PhCH₂SO₂Cl, CH₂Cl₂; (e) R³CHO or

R³CH(OEt)₂, TFA, Et₃SiH; (f) NaOH, THF, MeOH.

the desired thiol nucleophile. Thioether 38 was then oxidized

with TPAP/NMO to the sulfone, and then the C2 substituent

was elaborated to the amine as shown earlier. The amine was

then sulfonylated and the ester hydrolyzed to yield the desired

45.

The synthesis of amine-linked analogues made use of the

same versatile intermediate 36, as shown in Scheme 5. In

this case, the alcohol was oxidized under Swern conditions

and the resulting aldehyde was treated with a primary or

secondary amine under reductive amination conditions to

install the benzoate. Both of these intermediates were then

elaborated at C2 to the amine as described above, then

sulfonylated, and the C3 ester was hydrolyzed to yield the

desired acids 58 and 60.

and that substitution in this ring could have a dramatic impact

on in vivo clearance in rats. The synthesis of the analogues was

accomplished by simply coupling the amino ester 79 (Scheme

8) with sulfonyl chlorides under Schotten-Baumann conditions.

This approach successfully provided much diversity at this

position with the C3 oxygen linked series. More challenging

was the fact that only a handful of substituted phenylmethane

sulfonyl chlorides were commercially available at the time

of this work. We used a variety of literature methods⁵¹to

synthesize reagents (see Scheme 6) and modiﬁed conditions to

generate more difﬁcult to synthesize compounds such as the

2,6-disubstituted reagents shown in Scheme 7. It is has been

reported⁵²that under standard conditions to synthesize sulfonyl

chlorides from benzyl halides, extrusion of SO₂occurs, returning

starting halide and signiﬁcantly lowering the yield of the desired

sulfonyl chloride. Therefore, reaction conditions were modiﬁed

We next varied the substituent on the sulfonamide portion

of the molecule. Earlier SAR⁴⁴had shown that a benzyl

substituent was much more potent than unsubstituted phenyl

Indole Cytosolic Phospholipase A₂R Inhibitors

Scheme 2. Synthesis of a Propyl C3 Linker^a

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3391

^a(a) Methyl 4-(2-formylethyl)benzoate, TFA, Et₃SiH; (b) NaH, DMF, BrCH(Ph)₂; (c) NBS, benzoyl peroxide, CCl₄; (d) Ag₂CO₃, H₂O, acetone; (e)

CH₃NO₂, NH₄OAc, reﬂux; (f) Zn(Hg) amalgam, HCl, THF; (g) NaHCO₃, PhCH₂SO₂Cl, CH₂Cl₂; (h) NaOH, THF, MeOH.

Scheme 3. Synthesis of C3 Sulfone Benzoate Linker^a

^a(a) tBDPSCl, imidazole, DMF; (b) methyl 4-[(2-oxoethyl)thio]benzoate,⁴¹TFA, Et₃SiH; (c) NaH, DMF, BrCH(Ph)₂; (d) NMO, TPAP; (e) TBAF, THF;

(f) MsCl, Et₃N; (g) NaN₃, DMF, 60 °C; (h) PPh₃, H₂O, THF; (i) NaHCO₃, PhCH₂SO₂Cl, CH₂Cl₂; (j) NaOH, THF, MeOH.

as shown in Scheme 7 to avoid this. Speciﬁcally, we found that

if the sodium salt of the sulfonic acid, e.g., 74, is protonated

with gaseous HCl before treatment with oxalyl chloride, the

yield of sulfonyl chloride 77 increases from <10% without HCl

treatment to reproducibly ∼90%. This method was also ap-

plicable to monosubstituted benzyl halides. The reaction thus

performed was amenable to scale-up.

With these sulfonyl chloride reagents in hand, variations to

the sulfonamide were quickly explored using the route shown

in Scheme 8 for the C3 ether linked amine.

This same approach was used to make sulfonamide

analogues with C3 methylene and sulfone linkers shown in

Scheme 9. Sulfone propionates were made as shown in

Scheme 10 from the amino methyl ester previously described

3392 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

Scheme 4. Synthesis of C3 Sulfone Propionate Linked Analogues^a

^a(a) DPPP, CBr₄; (b) K₂CO₃, methyl-3-(4-mercaptophenyl)propionate, DMF; (c) NMO, TPAP, ACN; (d) TBAF, THF, H₂O; (e) MsCl, Et₃N, CH₂Cl₂; (f)

NaN₃, DMF, 60 °C; (g) PPh₃, THF, H₂O; (h) PhCH₂SO₂Cl, NaHCO₃, CH₂Cl₂; (i) NaOH, THF, H₂O.

Scheme 5. Synthesis of C3 Amine Linked Analogues^a

^a(a) oxalyl chloride, DMSO, DIPEA; (b) NaBH(OAc)₃, methyl 4-aminobenzoate for 47 and methyl 4-(methylamino)benzoate for 49; (c) TBAF, THF,

HOAc; (d) MsCl, NEt₃; (e) NaN₃; (f) PPh₃,THF, H₂O; (g) H₂, Pd/C; (h) PhCH₂SO₂Cl, NaHCO₃, CH₂Cl₂; (i) NaOH, THF, MeOH.

(43 in Scheme 4) or from the amino ethyl ester synthesized

using similar chemistry. The chemistry described herein

allowed the synthesis of multiple analogues and allowed a

full SAR to be developed. The chemistry was also versatile

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3393

Scheme 6. Synthesis of Novel Sulfonyl Chlorides^a

shown this region to be very important in both enabling

nanomolar inhibitors and providing a platform for substitutions

that would attenuate the high clearance seen with 141. Previ-

ously, halogens had been used to probe space around this ring;

a broader scan of allowed functionality is shown in Table 2.

Both the nitro group and cyano group were allowed at all

positions. Substitution of the phenyl ring by the three pyridyl

regioisomers also resulted in very potent compounds. This

substitution allows a decrease of ∼1.5 log units of clogP and

indicates the feasibility of using this region to modify physi-

cochemical properties. Other interesting analogues include the

cyclohexyl and the napthyl analogues, both of which were quite

potent. The ability to substitute around all positions of the phenyl

ring, incorporate polarity or increased size renders this sulfona-

mide region a versatile part of the pharmacophore.

^a(a) Na₂SO₃, EtOH; (b) SOCl₂, DMF.

With the knowledge gained from varying the linker to the

acid functionality and a broader understanding of the allowed

functionality at the sulfonamide region, it seemed prudent to

explore variations at the sulfonamide with some of the more

potent linkers. These data are summarized in Table 3. Com-

pounds that had increased potency over 141 and 2 with lower

in vivo clearance values were desired. All four potent linkers

were examined with multiple sulfonamide substitution patterns,

and assay data and rat clearance (CL) after iv administration

are reported in Table 3. From the unsubstituted analogues, only

methylene linker 24 is potent and cleared slowly in vivo. The

3,4-dichloro substitution remarkably lowered the clearance in

2, 111, 113, and 138 when compared to their unsubstituted

counterparts while also maintaining potency. In fact, 111 showed

the pattern sought, a low nanomolar inhibitor that was cleared

quite slowly. More focus was given to 2-substition and 2,6-

disubstitution of the sulfonamide. The 2-chloro analogues were

all quite potent, but unfortunately all of these analogues, with

the exception of 115, showed rapid clearance. The 2-methyl

analogues were also potent and typically had reduced clearance

when compared to the 2-chloro analogues. The 2,6-dimethyl

substitution also yielded very potent compounds, now with

acceptable clearance (<20 (mL/min)/kg). In fact 121 is signiﬁ-

cantly more potent while being cleared much more slowly than

2. The 2,6-diﬂuoro substituents were also explored with each

linker and also yielded very potent analogues. Unfortunately,

most of these compounds were also cleared rapidly and were

unsuitable for further in vivo studies. The trends seen in this

table were that 2- and 2,6-substitution patterns generally resulted

in more potent compounds. The 2,6-dimethyl substitution

increased potency and resulted in compounds with attenuated

clearance, whereas the 3,4-dichloro analogues maintained

potency but also had reduced clearance. Within a given series,

the clearance was dependent on the linker; the methylene linkers

were cleared more slowly, while the sulfone benzoates and

propionates were cleared much more rapidly. Several examples

of oxygen and methylene linked analogues were chosen for

further in vitro and in vivo validation.

Scheme 7. High Yielding Synthesis of Hindered Sulfonyl

Chlorides^a

^a(a) (i) Na₂SO₃, TBAI, H₂O; (ii) HCl (g), CH₃OH; (b) oxalyl chloride,

THF.

enough to allow the synthesis of key compounds on gram

scale for further characterization.

Results and Discussion

Previous SAR had elucidated that a three atom linker to a

benzoic acid at the C3 position of these indole cPLA₂R inhibitors

was essential for well-behaved inhibitors.⁴¹Subsequently,

extension at C2 through an ethyl bridge to a benzyl sulfona-

mide⁴⁴was determined to be essential for nanomolar potency

in both isolated enzyme and whole blood assays. Once this level

of potency was achieved, the C3 linker was revisited. Table 1

displays variations to the C3 substituent. First, shortening the

benzoic acid linker, or sliding the benzene ring closer to the

indole while maintaining the distance, as in 9-13, dramatically

reduced potency when compared to 141.⁴⁴When the benzene

was replaced with an oxadiazole, 15, potency was again

signiﬁcantly reduced. When the benzoic acid was extended to

a propionic acid, 17, potency was maintained. This SAR trend

had also been observed in compounds that were signiﬁcantly

less potent. When the linker was modiﬁed to the all carbon linker

24 or the sulfone linker 35, potency in both assays increased

signiﬁcantly. Sulfone propionate 45 was the most potent

compound in the rat whole blood assay with a low nanomolar

IC₅₀. When a secondary or tertiary amine linker, 58 or 60, was

examined, potency dropped off dramatically. The compounds

that were most promising were the ether, methylene, and sulfone

benzoates and propionates. It is difﬁcult to speculate as to what

property caused the increase in potency in this series because

effects on benzoic acid pK_aor hydrogen bond donor/acceptor

properties do not correlate with the observed potency changes.

This quick re-examination of the C3 linker gave a deﬁned group

of very potent compounds to further optimize.

As noted earlier, the GLU micelle assay can ﬁlter out

compounds that are presented as false positives by disrupting

the membrane/water interface without forming 1:1 interactions

with cPLA₂R. We note that at the GLU micelle IC₅₀values

listed in Table 3, which vary from 0.15 to 0.004 µM, there are

>7000 to >250 000 molecules of triton or lipid for every

molecule of inhibitor. Therefore, we felt it was likely that these

molecules bind directly to cPLA₂R and do not affect the

membrane surface.

Another region of the pharmacophore that was ripe for further

Since 111 and 121 combined the properties of high potency

and low clearance, these compounds were characterized more

optimization was the benzyl sulfonamide. Previous efforts⁴⁴had

3394 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

Scheme 8. Sulfonamide Analogues with a C3 Ether Linkage^a

McKew et al.

^a(a) RSO₂Cl, NaHCO₃, CH₂Cl₂; (b) NaOH, THF, MeOH.

carefully. After conﬁrmation that both inhibitors were reversible

inhibitors in the GLU micelle assay, their binding properties

were measured by isothermal titration calorimetry (ITC) using

triton micelles analogous to those used in the GLU micelle

assay.⁵³In ITC, cPLA₂R in the presence of micelles is titrated

with inhibitor also in the presence of micelles, and the heat

released with each equal addition of inhibitor is measured until

cPLA₂R is saturated with compound. No detectable heat was

generated when inhibitors were titrated against assay buffer

alone. The binding to cPLA₂R is exothermic for both com-

pounds, and the isotherm ﬁts well with a single site model,

indicating that one molecule of each inhibitor interacts with one

molecule of cPLA₂R. The K_dfor 111 was determined to be

0.067 and 0.013 µM for 121. These values agree with the IC₅₀

values from the GLU micelle assays, which are 0.04 and 0.01

µM respectively.

Two isoforms of cPLA₂R were initially identiﬁed, cPLA₂ꢀ

and cPLA₂γ, while more recently, three additional isoforms

closely related to cPLA₂ꢀ were identiﬁed.⁵⁴To assess selectivity,

111 and 121 were assayed for their ability to inhibit cPLA₂ꢀ

and γ, which are ∼35% identical in the catalytic domains. By

use of PAPC (1-palmitoyl-2-arachidonoyl-sn-glycero-3-phos-

phocholine) liposomes to assess activity, 111 and 121 both

showed greater than 90% inhibition of cPLA₂R at a concentra-

tion of 0.020 µM but no inhibition with cPLA₂ꢀ, and cPLA₂γ

at concentrations as high as 0.5 µM. Similarly, by use of PAPE

(1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphoethanola-

mine) liposome assays to monitor inhibition of type II secreted

phospholipase A₂(sPLA₂), both compounds inhibited cPLA₂R

in this assay with IC₅₀< 0.010 µM but did not inhibit sPLA₂

at 0.5 µM.

MC-9 cells are a murine mast cell line that can be stimulated

through the IgE receptor to activate release of arachidonic acid

from the cellular membrane⁴⁴resulting in generation of pros-

taglandins by the COX-1 pathway and leukotrienes by the 5-LO

pathway. As expected, the 5-LO inhibitor zileuton^55,56(N-[1-

(1-benzothien-2-yl)ethyl]-N-hydroxyurea) selectively inhibits LT

production in this assay but does not effect PG production. The

COX-1 dependence of the assay was conﬁrmed using SC-560⁵⁷

(5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(triﬂuoromethyl)-

1H-pyrazole) and celecoxib,⁵⁸(4-[5-(4-methylphenyl)-3-(triﬂu-

oromethyl)-1H-pyrazol-1-yl]benzenesulfonamide), which are

structurally related but highly selective for COX-1 and COX-

2, respectively (see Table 4). The COX-1-dependent PG

synthesis can also be initiated by bypassing cPLA₂R with the

addition of exogenous AA directly to the cells. In this case,

NSAIDs such as naproxen ((2S)-2-(6-methoxy-2-naphthyl)pro-

panoic acid) and COX-1 selective inhibitors will still inhibit

PG production, but a selective cPLA₂R inhibitor should not.

When 111 and 121 were tested in this assay, they were found

to inhibit LT and PG production with similar IC₅₀values for

each pathway, suggesting inhibition of AA release. When

cPLA₂R was bypassed by the addition of exogenous AA, the

inhibitors did not affect PGF₂R production, indicating that they

do not inhibit COX-1.

111 was also tested in a COX-2 dependent PGE₂⁵⁹assay using

A549 cells. In this assay, A549 cells are stimulated overnight

with IL-1B to induce COX-2 expression, and the medium is

removed and replaced with medium containing either inhibitor

alone or inhibitor plus exogenous AA. Celecoxib inhibits PGE₂

production in the presence or absence of AA. In contrast, 111

inhibited PGE₂production by >95% at 0.040 µM in the absence

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3395

Scheme 9. Sulfonamide Analogues with a C3 Methylene and Sulfone Linkers^a

^a(a) RSO₂Cl, NaHCO₃, CH₂Cl₂; (b) NaOH, THF, MeOH.

of exogenous arachidonate but was inactive at 1 µM when

cPLA₂R was bypassed with exogenous AA. This assay adds

additional evidence that 111 acts through the inhibition of

cPLA₂R in cells.

Finally, 111 and 121 were also assayed for their ability to

inhibit COX-1 and 2 in microsomes in a colorimetric COX assay

(Cayman Chemical) where the oxidation of N,N,N′,N′-tetrameth-

ylbenzene-1,4-diamine, TMPD, is monitored. No inhibition was

observed at 100 µM.

Inhibition of these inhibitors in a human whole blood (HWB)

assay was also examined. The rat and human⁴⁴whole blood

assays are similar except the A23187 concentration required

for consistent stimulation is 30 µM for human blood vs 5 µM

for rat. In addition, we test for a broader range of AA metabolites

and also monitor PAF production. The results in Table 5 indicate

that these inhibitors are acting on cPLA₂R where they can block

the initial cleavage of arachidonoyl phospholipids to generate

free AA and lyso-PC, which is the precursor to PAF.

The data presented above were sufﬁcient to convince us that

these inhibitors were potent and selective inhibitors of cPLA₂R

capable of inhibiting multiple classes of inﬂammatory mediators.

The in vivo clearance value, presented in Table 3, shows both

of these compounds to be cleared quite slowly in rats. The

pharmacokinetics from oral dosing for both inhibitors were

examined as a prelude to in vivo pharmacology models, and

the oral bioavailability (F) for 111 and 121 in rats was 6% and

4%, respectively. Despite this low bioavailability, the plasma

levels from reasonable po doses exceeded the rat whole blood

IC₅₀values, and therefore examination of the in vivo efﬁcacy

of these compounds was warranted. These compounds were

compared to 2, which has slightly better bioavailability but lower

potency and higher clearance. In estimating in vivo potential,

we found oral exposure following 25 mg/kg po dosing divided

by the IC₅₀in rat whole blood to be informative for prioritizing

compounds. These AUC/IC₅₀values are listed in Table 6.

The strategy for evaluating these compounds in vivo was to

explore standard inﬂammation and asthma models in which AA

metabolites play a central role. COX-2 selective inhibitors and

NSAIDs have been characterized previously in short-term

models, including the rat air pouch model^57,60,61and the

carrageenan paw edema (CPE) model.⁶²In the air pouch model,

carrageenan is injected into a preformed air pouch 2 h after po

administration of drug. Air pouch contents are then removed

6 h later, and the amount of PGE₂produced is quantitated. In

developing the assay internally, we demonstrated that celecoxib

administered at 2 mg/kg ip inhibited ∼90% of the PGE₂

production. For each of the cPLA₂R inhibitors tested, the

maximum inhibition of PGE₂was >90%. As shown in Table

6, all three compounds were active, with 121 the most potent.

The ED₅₀for 2 was more variable, but when tested head to

head with 121, in multiple experiments at 5 mg/kg, 121 gave

>50% inhibition whereas 2 showed <10%. This is consistent

with the predictions of relative potency from the AUC/IC₅₀

values.

The rat CPE model has been used extensively to evaluate

NSAIDS and selective COX-2 inhibitors, and activity in this

model correlates well with clinical efﬁcacy in man.⁶³In this

model, compound is administered 2 h before subplantar injection

of carrageenan and the inhibition of swelling over the next 3 h

is measured. The maximum inhibition effect observed is ∼50%

3396 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

Scheme 10. Sulfonamide Analogues with Sulfone Propionate Linkers^a

^a(a) TFA, Et₃SiH, ethyl 4-(2-oxoethyl)sulfanylpropanoate; (b) NaH, DMF, BrCH(Ph)₂; (c) NMO, TPAP; (d) TBAF; (e) MsCl, NEt₃; (f) NaN_3,DMF, 60°

C; (g) PPh₃, H₂O, THF; (h) RSO₂Cl; NaHCO₃, CH₂Cl₂; (i) NaOH, THF, MeOH.

when dosed with naproxen po at a dose of g10 mg/kg, and the

ED₅₀is deﬁned as the dose that inhibits 25%, or half-the

maximal value. Again, 121 was superior to 111 and 2 (see Table

6). The differential between 111 and 2 was less pronounced

presumably because the main advantage of 111 is slower

clearance, which is less important in this short-term model. In

ﬁve independent experiments where 121 and celecoxib were

compared at 25 mg/kg to determine the near maximum effect,

the inhibition of edema was essentially identical at 34 ( 9%

for 121 and 37 ( 15% for celecoxib (reported as % inhibition

of edema ( SE).

To characterize these compounds in a long-term model, 2,

111, and 121 were tested in the mouse collagen-induced arthritis

(CIA) model, which has many immunological and pathological

similarities to human rheumatoid arthritis. We had previously

reported that cPLA₂R deﬁcient mice were resistant to disease

in this model.¹²Efﬁcacy was assessed in a semitherapeutic

dosing regimen, which involved scoring and assignment to

treatment groups when 10% of the mice showed disease

symptoms. All animals were scored daily in a blinded fashion

for signs of disease symptoms. The data in Table 7 represent a

summary of the scores in the treatment groups compared to the

vehicle groups in each experiment. Both 121 and 111 (tested at

a single dose level of 100 mg/kg, b.i.d.) gave a dramatic

reduction in the clinical disease severity score relative to the

vehicle treated group, whereas 2 with its poorer potency relative

to 121 was only marginally effective. The reduction in disease

score correlated with the histological assessment where each

paw was assigned a numerical score for arthritis severity and

the general number of joints affected. In addition, the 121 and

111 animals had a high percentage of paws with grade 0 arthritis

(>80%) and no paws with grade 4 (severe) arthritis. In contrast,

17% of vehicle treated mice had a severity score of 4 and only

39% of the paws were unaffected. We were surprised that 111

outperformed 121 in this study and also in a repeat study, but

plasma levels taken at the end of the experiment with time points

spanning the peak and trough plasma levels showed that the

exposure of 111 was signiﬁcantly higher than that seen for 121.

To further assess efﬁcacy in long-term models predictive of

clinical utility, 111 and 121 were studied in adjuvant-induced

arthritis (AIA) in Lewis rats. Adjuvant arthritis was induced in

Lewis rats by intradermal injection of complete Freund’s

adjuvant at the base of the tail. Treatment was begun at day 8

when mean clinical joint scores were 12 and continued for 11

days, and the hind paws were scored daily for clinical signs of

arthritis. Treatment with celecoxib, 111, and 121, at doses as

low as 5 mg/kg, rapidly reduced the mean clinical joint scores

to levels between 0 and 1. At the completion of the 11-day

experiment, the tarsal joints were collected at necropsy and

prepared for histologic examination, and the arthritic lesions in

each animal were evaluated in a blinded fashion. Each tarsal

was assigned a numerical score for synovitis (synovitis score,

0–11, 11 is most severe) and cartilage damage⁶⁴(Mankin score,

0–14, 14 most severe). As can be seen in Table 8, 111, 121,

and celecoxib were efﬁcacious with a clear, statistically

signiﬁcant reduction in synovitis and cartilage damage at all

doses. There was no statistically signiﬁcant difference between

the nonvehicle treated groups.

Allergen-induced reversible airway bronchoconstriction and

acute hyperresponsiveness (AHR) are two hallmark features of

allergic asthma that can be examined in vivo in a sheep model

of asthma. Studies performed in this animal model present strong

evidence that the release of AA metabolites plays an important

role in the development of late bronchial responses to antigen

Indole Cytosolic Phospholipase A₂R Inhibitors

Table 1. SAR from C3 Linker Variations

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3397

compared to historical control values pre- and postantigen

challenge. As can be seen from Table 9, both cPLA₂R inhibitors

dramatically attenuated the late phase bronchocontriction be-

cause of allergen challenge and AHR as measured by a

secondary carbachol challenge. Activity in this model shows

that cPLA₂R inhibitors display signiﬁcant efﬁcacy in LT

dependent in vivo models.

These indole cPLA₂R inhibitors are potent and selective in a

variety of stringent assay formats in vitro and in vivo. All of

the previously reported inhibitors of this target tend to be large

lipophilic molecules or have electrophilic ketones or both. The

potent inhibitors disclosed here also are large, but notably,

increases in molecular weight in areas allowed by the pharma-

cophore⁴⁴have returned substantial increases in potency. The

stringent assays used to evaluate these compounds have proven

to resist false positives and as such accurately reﬂect binding

to the target. One way to examine this trend is through the

concept of ligand efﬁciency.^70,71The graph in Figure 2

represents on the Y axis the log of the IC₅₀of all of the indole

cPLA₂R inhibitors, and heavy atom count is on the X axis. What

can be clearly seen is the trend that when molecular weight is

added in an allowed part of the pharmacophore, potency is

increased (along the top of the curve) and when molecular

weight is added in places not allowed by the pharmacophore,

potency is lost (bottom of the curve). The initial validated hits⁴¹

are the two blue triangles with atom count of ∼36. These

compounds were optimized to the three blue triangles, from

bottom to top 2, 111, 121. A signiﬁcant increase in potency

was gained from the increase in molecular weight. It can also

be seen that without increasing atom count further, increases

in potency could be attained. The top of the curve continues to

increase beyond the highlighted compounds; however, the trade

off between atom count and potency becomes less appealing.

In summary we have disclosed a group of indole cPLA₂R

inhibitors that are potent and selective. These compounds are

potent in stringent isolated enzyme assays, cell-based assays,

and rat and human whole blood assays, and their binding has

been further characterized using isothermal titration calorimetry.

Examples from this series have been proﬁled in vivo in both

PG and LT dependent models and have shown impressive

efﬁcacy when dosed po. These are the ﬁrst cPLA₂R inhibitors

to show PO in vivo efﬁcacy⁷²in this broad a class of in vivo

models, and as such, they begin to demonstrate the therapeutic

potential of cPLA₂R inhibitors. Clinical trials to evaluate the

efﬁcacy of 111 in humans have been initiated, and 121 continues

to be proﬁled in preclinical models. Additional in vivo efﬁcacy

data will published shortly.

^aAssay protocol reported previously.⁴¹Values are generated from at

least two runs, and each run consists of a mean value generated from

duplicate assays. ^bAssay protocol reported previously.⁴¹Values are

generated from at least two runs, and each run consists of a mean value

generated from triplicate assays. ^cNT ) not tested.

Experimental Section

Chemistry General Procedures. All solvents and reagents were

used as obtained. All reaction mixtures were stirred using a magnetic

stir bar, and reactions were conducted at room temperature unless

otherwise noted. Aqueous workup was performed using H₂O and

brine, and organic solutions were dried with MgSO₄unless

otherwise noted. Proton NMR spectra were recorded on a 300 MHz

Varian Gemini 2000, a 400 MHz Bruker AV-400, or a 500 MHz

Bruker AV-400 using TMS (δ 0.0) as a reference. Combustion

analyses were obtained using a Perkin-Elmer series II 2400

CHNS/O analyzer or by Robertson-Microlit. High resolution mass

spectra were obtained using a Bruker (Billerica, MA) APEXIII

Fourier transform ion cyclotron resonance (FT-ICR) mass spec-

trometer equipped with an actively shielded 7 T superconducting

magnet (Magnex Scientiﬁc Ltd., U.K.) and an external Bruker

APOLLO electrospray ionization (ESI) source. Flash chromatog-

raphy was performed using EM Science 230–400 mesh silica gel

or Biotage ﬂash columns packed with KP-SIL 60 Å silica gel. Thin-

challenge.⁶⁵The 5-LO inhibitor zileuton blocks allergen-induced

late airway responses, inﬂammation, and AHR⁵⁵in this model,

whereas a continuous iv infusion of the selective LTD₄receptor

antagonist montelukast attenuates both the early and late-phase

asthmatic responses.^66,67PAF has also been implicated in the

late-phase response in this model, suggesting^68,69that a more

complete blockade of lipid mediators by a cPLA₂R antagonist

may be beneﬁcial. When cPLA₂R inhibitors 121 and 111 where

dosed po b.i.d. the day before and 2 h before the time of antigen

challenge, they both had a dramatic impact on the late asthmatic

response (LAR) as shown in Table 9. A fourth po dose was

then administered 8 h after antigen challenge. The following

day AHR due to aerosolized carbachol was measured and

3398 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

Table 2. Sulfonamide Analogues of 141

McKew et al.

IC₅₀(µM)

b

compd

X

GLU micelle^a

RWB TXB₂

compd

X

GLU micelle

RWB TXB₂

141

81

83

85

87

89

Ph

0.11

0.085

0.11

0.16

0.06

0.30

0.12

0.03

0.07

0.09

0.07

0.16

91

93

95

97

99

4-CN Ph

2-Pyr

3-Pyr

4-Pyr

cyclohexyl

2-napthyl

0.26

0.4

0.22

0.18

0.20

0.23

0.15

0.35

0.36

0.34

0.15

0.14

2-NO₂Ph

3-NO₂Ph

4-NO₂Ph

2-CN Ph

3-CN Ph

101

^aAssay protocol reported previously.⁴¹Values are generated from at least two runs, and each run consists of a mean value generated from duplicate

assays. ^bAssay protocol reported previously.⁴¹Values are generated from at least two runs, and each run consists of a mean value generated from triplicate

assays.

Table 3. Effect of substitution on potency and clearance in the rat

Table 4. MC-9 Assay

inhib LTB₄

inhib PGF₂R

(IC₅₀, µM)

inhib PGF₂R w/AA

stimulation (IC₅₀, µM)

compd

111

121

zileuton

SC-560

celecoxib

naproxen

(IC₅₀, µM)^a

0.020

0.012

0.55

not active

0.020

0.006

not active

<0.005

0.40

0.900

>1

not active

<0.005

0.30

0.20

0.33

^aAssay protocol reported previously.⁴⁴Values are generated from at

least two runs, and each run consists of a mean value generated from

duplicaate assays.

IC₅₀(µM)

R²GLU micelle^aRWB TXB₂(mL/min)/kg^c

rat CL

b

compd

X

n

R¹

Table 5. Activity in Human Whole Blood Assays

141

24

35

45

2

O

0 H

H

0.11

0.07

0.02

0.03

0.15

0.04

0.02

0.04

0.05

0.02

0.01

0.06

0.03

0.01

0.004

0.18

0.06

0.02

0.07

0.12

0.07

0.08

0.02

0.16

0.07

0.15

0.04

0.05

0.03

0.06

0.02

0.03

0.02

0.03

0.07

0.08

0.36

0.15

0.02

69

13

54

150

14

5

19

10

>200

7

71

63

18

6

13

3

25

32

10

186

52

% inhibition 121

at 0.039 µM^a

% inhibition 111

at 0.15 µM

CH₂0 H

SO₂0 H

SO₂2 H

mediator

TXB₂

LTB₄

PGE₂

PGF_2R

PAF

72^b

78^b

79^b

72^b

57^b

57^d

64^d

78^d

66^d

50^c

O

0 3-Cl 4-Cl

111 CH₂0 3-Cl 4-Cl

113 SO₂0 3-Cl 4-Cl

136 SO₂2 3-Cl 4-Cl

^aAssay protocol reported previously.^{44 b}Average of 10 different donors.

^cAverage of 2 different donors in 6 different experiments. ^dAverage of 14

different donors.

103

O

0 2-Cl

H

115 CH₂0 2-Cl

117 SO₂0 2-Cl

138 SO₂2 2-Cl

105

119 CH₂0 2-Me H

107 0 2-Me 6-Me

121 CH₂0 2-Me 6-Me

123 SO₂0 2-Me 6-Me

109

125 CH₂0 2-F 6-F

127 SO₂0 2-F 6-F

140 SO₂2 2-F 6-F

^aAssay protocol reported previously.⁴¹Values are generated from at

least two runs, and each run consists of a mean value generated from

duplicate assays. ^bAssay protocol reported previously.⁴¹Values are

generated from at least two runs, and each run consists of a mean value

generated from triplicate assays; ^cSee Experimental Section for rat

pharmacokinetic protocol.

O

0 2-Me H

Table 6. PO Efﬁcacy in Short-Term Prostaglandin Dependent Models

AUC (µM h)/

ED₅₀(mg/kg) for air

ED₅₀(mg/kg) for

O

compd IC₅₀(µM)^apouch PGE₂inhibition, po^bCPE inhibition, po^c

2

18

70

160

10–25

6

3.5

40

35

8

O

0 2-F 6-F

111

121

^aThe AUC was determined at 25 mg/kg po PK experiment, and the

IC₅₀is from the rat whole blood assay (see Experimental Section). ^bData

are derived from more than two independent dose response experiments

for each compound, with six to eight mice per group (see Experimental

Section for details). ^cData are derived from more than three independent

dose response experiments for each compound, with 10 mice per group

(see Experimental Section for details).

(3.0 equiv). After being stirred at 0 °C for 1 h, the reaction mixture

was warmed to room temperature and the appearance of product

detected by TLC. The reaction was then quenched with saturated

sodium bicarbonate, diluted with CH₂Cl₂, washed with H₂O and

brine, dried, and puriﬁed by column chromatography to yield the

desired product.

General Procedure for Indole N-Alkylation with Bromo-

diphenylmethane. A solution of the indole (1.0 equiv) in DMF

(0.6 M) was added to a mixture of sodium hydride (60% dispersion,

layer chromatography (TLC) was performed using EMD 250 µm

prescored silica gel 60 F₂₅₄plates. Purity in two solvent systems

(H₂O-CH₃CN and H₂O-MeOH) was determined using an Agilent

1100 HPLC instrument, and all ﬁnal compounds were >95% pure

(see Supporting Information for details).

General Procedure for Indole Reductive Alkylation. To the

indole (1.0 equiv) and the aldehyde or acetal (1.1 equiv) in CH₂Cl₂

(0.06 M) at 0 °C was added HSiEt₃(3.0 equiv) followed by TFA

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3399

Table 7. Disease Severity Scores and Histological Scores in the Mouse CIA

mean disease severity score

histological severity score

plasma levels

plasma level

compd^a

at day 31^b( SE (0–16)

at day 31^c(0–4)

(ng/mL), peak concn^d

(ng/mL), trough concn^e

vehicle

2

111

121

6.7 ( 1.1

4.6 ( 0.9

0.83 ( 0.4

1.3 ( 0.7

1.28

1.5

0.22

0.23

4085

7195

923

531

2315

118

^aCompounds dosed 100 mg/kg PO, BID, with 10 mice /group, see experimental section for full details; ^bEach paw was scored daily using a 0–4 scale

(4 is severe), the maximum score is 16. ^csee experimental section for full details, 4 is most severe ^dSamples by eye bleed at 1.5 h post dose for 2 and 3 h

post dose for 111 and 121. ^eSamples 12–14 h after last dose via end bleed.

Table 8. Histological Scoring of Synovitis and Cartilage Damage in the AIA Model

compd

vehicle

111, 50 mg/kg

111, 25 mg/kg

111, 5 mg/kg

121, 50 mg/kg

121, 25 mg/kg

121, 5 mg/kg

total synovitis score^a(0–11)

Mankin score,^64,b(0–14)

plasma levels (ng/mL)^c(4 h)

plasma level (ng/mL) (16 h)

10.00 ( 1.38

4.33 ( 2.14^d

5.08 ( 2.71^d

5.67 ( 1.69^d

4.75 ( 1.70^d

6.58 ( 0.92^d

6.67 ( 1.75^d

4.42 ( 2.31^d

8.83 ( 0.97

4.92 ( 1.24^e

4.67 ( 2.27^e

5.33 ( 1.21^e

5.25 ( 1.44^e

6.25 ( 0.69^e

6.25 ( 0.76^e

5.17 ( 1.33^e

3598 ( 838

1126 ( 350

147 ( 106

1140 ( 487

698 ( 325

69 ( 44

692 ( 493

166 ( 45

34 ( 16

110 ( 20

73 ( 31

26 ( 10

129 ( 83

celecoxib, 5 mg/kg

1130 ( 336

^aTotal score ( SD; 11 is most severe. ^bTotal score ( SD; 14 is most severe. ^cPlasma at approximately t_max, (SD (see Experimental Section for full

details). ^dPlasma at trough levels, (SD (see Experimental Section for full details). ^eLower than vehicle, P < 0.05.

Table 9. PO Efﬁcacy Data in Ascaris Suum Airway Challenge with

Naturally Sensitized Sheep

a rate that maintained the temperature below 0 °C. The cooling

bath was removed, and the reaction mixture was stirred at room

temperature for 30 min, ﬁltered, concentrated to an oil, and then

azeotroped with toluene. This crude sulfonic acid was then dissolved

in THF (0.5 M) and DMF (catalytic amount, 1 g of DMF/20 g of

sulfonic acid) and cooled to –20 to –10 °C. Oxalyl chloride (3.5

equiv) was added slowly, and then the reaction was maintained at

this temperature until LC/MS showed complete conversion to the

desired sulfonyl chloride. The solvent volume was reduced in half

in vacuo, the mixture was cooled to –20 to –10 °C, and then water

was cautiously added to quench the excess oxalyl chloride. The

THF/H₂O was further concentrated and then cooled to 10 °C to

allow the desired sulfonyl chloride to precipitate. The sulfonyl

chloride was collected by ﬁltration, dried in vacuo at room

temperature, and then used without further puriﬁcation. Alternatively

the sulfonyl chloride could be puriﬁed by low-temperature recrys-

tallization from petroleum ether.

early asthmatic

response^b

late asthmatic^c

response

compd^a

AHR^d

111

121

no effect

partial blockade

complete blockade

^aCompounds dosed at 10 mg/kg b.i.d. 24 h before challenge and 2 h

before challenge to generate the EAR and LAR data. Then a fourth dose

was given 8 h after challenge, and 16 h later AHR was measured. N ) 2

sheep. ^bNo effect is deﬁned as not signiﬁcantly different from controls.

^cPartial blockade deﬁned as approximately 50% reduction in lung resistance

compared to controls 5–8 h after challenge. Complete blockade deﬁned as

approximately 85% reduction in lung resistance compared to controls 5–8

h after challenge. ^dComplete blockade deﬁned as statistically equivalent

amount of carbachol needed to achieve a 400% increase in resistance before

and after antigen challenge.

1.1 equiv) in DMF (1.3 M) at 0 °C. The resulting brown reaction

mixture was stirred for 0.5 h at 0 °C, and then bromodiphenyl-

methane (1.1 equiv, 2.5 M solution in DMF) was added. The

mixture was allowed to warm to room temperature overnight and

then subjected to aqueous workup. The organic layer was dried,

ﬁltered, and evaporated to a solid that was puriﬁed by silica gel

chromatography.

General Procedure for Synthesis of Sulfonyl Chlorides A.

Step 1. A mixture of halide (1.0 equiv) and sodium sulﬁte (1.2

equiv) in H₂O (0.1 M) and EtOH (0.2 M) was heated to reﬂux

overnight. The mixture was cooled to room temperature and

concentrated until a precipitate began to form. The product was

collected by ﬁltration and azeotroped with toluene. The resulting

solid was used in the next step.

Step 2. To a suspension of the sodium sulfonate (1.0 equiv) in

CH₂Cl₂(0.1 M) were added DMF (0.7 equiv) and SOCl₂(3.9

equiv). After 1.5 h, the white suspension was concentrated and

azeotroped with toluene. The sulfonyl chlorides thus formed were

used without further puriﬁcation.

General Procedure for Synthesis of Sulfonyl Chlorides B. The

benzyl halide (1.0 equiv), sodium sulﬁte (1.05 equiv), and TBAI

(0.5 mg/mmol) were dissolved in H₂O (1.0 M) and warmed to 100

°C for 14 h. The mixture was cooled to room temperature, and the

voluminous precipitate was collected by ﬁltration and dried in a

vacuum oven. The aqueous ﬁltrate was saturated with NaCl at 100

°C and then cooled to 0 °C, and a second crop of crystalline sodium

sulfate was collected by ﬁltration and dried in vacuo. These two

crops were combined and suspended in MeOH (0.09 M) to yield a

hazy solution at room temperature. This was cooled to –10 to 0

°C, and HCl gas (3.75 equiv) was bubbled through the mixture at

GeneralProcedureforSulfonylationofAminesviaSchotten-

Baumann Reaction. To a solution of the amine (1.0 mmol) in

CH₂Cl₂(10 mL) were added sulfonyl chloride (1.2 mmol) and

saturated NaHCO₃(10 mL). The resulting suspension was stirred

until the amine was consumed (TLC analysis in 10%

MeOH-CH₂Cl₂). The mixture was diluted with CH₂Cl₂(20 mL),

washed with H₂O (20 mL) and brine, dried, and concentrated.

Puriﬁcation of the crude product by ﬂash chromatography

(EtOAc-hexanes) afforded the sulfonamide.

General Procedure for Ester Hydrolysis. To a solution of the

ester (1.0 mmol) in inhibitor free THF (0.5 M) was added 1 N

aqueous NaOH or LiOH (3.0 mmol) and MeOH (0.5 M). The

mixture was heated at 50 °C until the ester starting material was

consumed (TLC analysis in 50% EtOAc-hexanes). The reaction

mixture was concentrated, and the residue was diluted with H₂O

and acidiﬁed to pH 1 using 1 N HCl. The resulting mixture was

extracted with EtOAc; the organic extracts were washed with H₂O

and brine, then were dried, concentrated, and lyophilized to afford

the carboxylic acid.

5-Chloro-1-(diphenylmethyl)-1H-indole-2-carbaldehyde (4).

A solution of 5-chloroindole-2-carboxaldehyde 3⁷³(3.12 g, 17.3

mmol) in DMF was added to a suspension of NaH (0.83 g of 60%

dispersion in mineral oil, 21 mmol) in DMF. After 30 min, a

solution of bromodiphenylmethane (4.12 g, 14 mmol) in DMF was

added. After 1 h aqueous workup was performed, and ﬂash

chromatography afforded the N-benzhydrylindole 4 (3.65 g, 62%

1

yield). H NMR (300 MHz, CDCl₃) δ 6.62 (d, J ) 9.1 Hz, 1 H),

6.95 (dd, J ) 9.2, 2.1 Hz, 1 H), 7.04-7.47 (m, 11 H), 7.62 (d, J

) 1.6 Hz, 1 H), 8.17 (s, 1 H), 9.82 (s, 1 H).

3400 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

Figure 2. Atom efﬁciency of indole cPLA₂R inhibitors.

2-[5-Chloro-1-(diphenylmethyl)-1H-indol-2-yl]ethanamine (6).

A mixture of aldehyde 4 (1.46 g, 4.2 mmol), NH₄OAc (1.30 g, 17

mmol), and MeNO₂(40 mL) was heated to reﬂux for 2 h. The

mixture was diluted with H₂O (100 mL) and brine (100 mL) and

extracted with EtOAc (3 × 150 mL). Aqueous workup was

performed to afford the nitro oleﬁn, 5, which was used without

Methyl 4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]methyl}benzoate (8). The general

reductive alkylation procedure was followed utilizing indole 7 (225

mg, 0.43 mmol), methyl 4-formylbenzoate (79 mg, 0.48 mmol),

Et₃SiH (0.21 mL, 1.3 mmol), and TFA (67 µL, 0.87 mmol). After

8 h, aqueous workup was performed, followed by ﬂash chroma-

tography (gradient elution with 10-30% EtOAc-hexanes) to afford

the C3 alkylated indole 8 (107 mg, 37% yield) as a brown oil. ¹H

NMR (300 MHz, CDCl₃) δ 2.40-2.53 (m, 2 H), 2.72-2.82 (m, 2

H), 3.72 (s, 3 H), 3.79-3.84 (m, 2 H), 3.90-3.95 (m, 2 H), 6.35

(d, J ) 8.8 Hz, 1 H), 6.64 (dd, J ) 8.8, 1.9 Hz, 1 H), 6.73 (s, 1 H),

6.88-6.98 (m, 7 H), 6.99-7.08 (m, 3 H), 7.08-7.12 (m, 2 H),

7.13-7.20 (m, 5 H), 7.75 (d, J ) 8.2 Hz, 2 H).

1

further puriﬁcation. H NMR (300 MHz, CDCl₃) δ 6.87 (d, J )

9.1 Hz, 1 H), 7.01-7.21 (m, 7 H), 7.31-7.41 (m, 6 H), 7.46 (d, J

) 13.2 Hz, 1 H), 7.62 (d, J ) 1.6 Hz, 1 H), 7.88 (d, J ) 13.2 Hz,

1 H). To a solution of the crude nitro oleﬁn (1.64 g, 4.2 mmol) in

THF (100 mL) and concentrated HCl (10 mL) was added Zn(Hg)

(prepared by shaking Zn dust (5.5 g, 84 mmol) and HgCl₂(0.55 g,

1.2 mmol) in 5% aqueous HCl (10 mL) and decanting the aqueous

phase). The nitro oleﬁn mixture was heated to reﬂux for 1.5 h,

cooled to room temperature, and ﬁltered through Celite. Concen-

trated aqueous NH₄OH solution (200 mL) was added to the ﬁltrate,

and the resulting mixture was stirred for 15 min. THF was removed

under reduced pressure. The aqueous layer was extracted with

CH₂Cl₂, and the combined organic layer was washed with brine,

dried (Na₂SO₄), and concentrated. Puriﬁcation by ﬂash chroma-

tography (gradient elution with 1% MeOH-0.1% Et₃N-CH₂Cl₂

to 10% MeOH-CH₂Cl₂) afforded the amine 6 (0.53 g, 35% yield,

4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphenyl-

methyl)-1H-indol-3-yl]methyl}benzoic acid (9). Hydrolysis of the

methyl ester (107 mg, 0.16 mmol) according to the general

procedure afforded the carboxylic acid 9 (80 mg, 75% yield) as a

1

tan solid. H NMR (300 MHz, DMSO-d₆) δ 2.65-2.86 (m, 4 H),

3.87-3.93 (m, 2 H), 3.99-4.06 (m, 2 H), 6.24 (d, J ) 8.8 Hz, 1

H), 6.58 (d, J ) 10.7 Hz, 1 H), 6.86-6.92 (m, 5 H), 6.97-7.03

(m, 2 H), 7.04-7.13 (m, 6 H), 7.14-7.24 (m, 6 H), 7.59-7.67

(m, 2 H).

1

two steps) as a pale-yellow foam. H NMR (300 MHz, CDCl₃) δ

Methyl (4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]methyl}phenoxy)acetate (10). Us-

ing the general reductive alkylation procedure, indole 7 (200 mg,

0.39 mmol) was reacted with methyl (4-formylphenoxy)acetate⁷⁴

(83 mg, 0.42 mmol) to afford the C3 alkylated indole 10 (50 mg,

1.42 (br s, 2 H), 2.85 (t, J ) 6.7 Hz, 2 H), 2.97 (t, J ) 6.5 Hz, 2

H), 6.35 (s, 1 H), 6.53 (d, J ) 9.1 Hz, 1 H), 6.79 (dd, J ) 8.9, 2.1

Hz, 1 H), 6.90 (s, 1 H), 7.02-7.17 (m, 4 H), 7.27-7.37 (m, 6 H),

7.49 (d, J ) 1.9 Hz, 1 H).

1

22% yield). H NMR (300 MHz, CDCl₃) δ 2.35-2.46 (m, 2 H),

N-{2-[5-Chloro-1-(diphenylmethyl)-1H-indol-2-yl]ethyl}-1-

phenylmethanesulfonamide (7). Amine 6 (1.1 g, 3.0 mmol),

R-toluenesulfonyl chloride (0.64 g, 3.3 mmol), and saturated

aqueous NaHCO₃(25 mL) were reacted according to the general

Schotten-Baumann procedure. After 3 h aqueous workup was

performed to afford the sulfonamide 7 (1.4 g, 90% yield) as a white

2.71-2.81 (m, 2 H), 3.59-3.61 (m, 3 H), 3.79-3.83 (m, 4 H),

4.42-4.46 (m, 2 H), 6.32 (d, J ) 8.8 Hz, 1 H), 6.58-6.66 (m, 2

H), 6.69 (s, 1 H), 6.86-6.93 (m, 5 H), 6.93-7.00 (m, 3 H),

7.05-7.11 (m, 4 H), 7.11-7.18 (m, 6 H), 7.21 (d, J ) 2.2 Hz,

1 H).

1

foam. H NMR (300 MHz, CDCl₃) δ 2.87 (t, J ) 6.9 Hz, 2 H),

(4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphenyl-

methyl)-1H-indol-3-yl]methyl}phenoxy)acetic acid (11). Hy-

drolysis of the methyl ester (46 mg, 0.066 mmol) according to the

general procedure afforded the carboxylic acid 11 (27 mg, 61%

yield) as a tan solid. ¹H NMR (300 MHz, DMSO-d₆) δ 2.78-2.98

3.07 (q, J ) 6.7 Hz, 2 H), 4.11 (s, 2 H), 4.17 (t, J ) 6.0 Hz, 1 H),

6.24 (s, 1 H), 6.55 (d, J ) 9.1 Hz, 1 H), 6.76-6.95 (m, 2 H), 7.07

(dd, J ) 5.6, 3.7 Hz, 4 H), 7.14-7.22 (m, 2 H), 7.22-7.38 (m, 9

H), 7.47 (d, J ) 1.6 Hz, 1 H).

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3401

(m, 6 H), 3.94 (s, 2 H), 4.20-4.24 (m, 2 H), 6.41 (d, J ) 8.8 Hz,

1 H), 6.67-6.78 (m, 3 H), 6.98-7.09 (m, 7 H), 7.21-7.31 (m, 5

H), 7.31-7.44 (m, 7 H).

7.28-7.35 (m, 6H), 7.49 (d, J ) 2.1 Hz, 1H). HRMS calcd for

[C₄₁H₃₉ClN₂O₅S + H] 705.219 54; found 705.219 28. Anal.

(C₄₁H₃₉ClN₂O₅S) C, H, N.

Methyl 3-(4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]methyl}phenyl)propanoate (12).

Using the general reductive alkylation procedure, indole 7 (220

mg, 0.42 mmol) was reacted with the methyl 3-(4-formylphenyl)-

propanoate⁷⁵(76 mg, 0.39 mmol) to afford the C3 alkylated indole

Methyl 4-[3-(5-Chloro-2-methyl-1H-indol-3-yl)propyl]ben-

zoate (18). 5-Chloro-2-methylindole (0.86 g, 5.2 mmol), methyl

4-(2-formylethyl)benzoate⁷⁷(1.0 g, 5.2 mmol), TFA (1.78 g, 15.6

mmol), and Et₃SiH (1.81 g, 15.6 mmol) were reacted according to

the general reductive alkylation procedure. The residue was puriﬁed

by ﬂash column chromatography with 10–20% EtOAc-hexanes

1

12 (50 mg, 7% yield). H NMR (300 MHz, CDCl₃) δ 2.37-2.52

1

(m, 4 H), 2.65-2.82 (m, 4 H), 3.47 (s, 3 H), 3.79 (s, 2 H), 3.85 (s,

2 H), 6.33 (d, J ) 8.8 Hz, 1 H), 6.63 (dd, J ) 8.8, 2.2 Hz, 1 H),

6.71 (s, 1 H), 6.88-6.98 (m, 9 H), 7.03-7.11 (m, 5 H), 7.13-7.18

(m, 5 H), 7.20 (d, J ) 1.9 Hz, 1 H).

to yield the desired 18 (1.67 g, 94% yield). H NMR (300 MHz,

CDCl₃) δ 1.88-2.04 (m, 2 H), 2.33 (s, 3 H), 2.65-2.76 (m, 4 H),

3.87-3.94 (m, 3 H), 7.06 (m, 1 H), 7.18 (m, 2 H), 7.24 (s, 1 H),

7.41 (d, J ) 1.9 Hz, 1 H), 7.76 (s, 1 H), 7.96 (d, J ) 8.2 Hz, 2 H).

Methyl 4-{3-[5-Chloro-1-(diphenylmethyl)-2-methyl-1H-in-

dol-3-yl]propyl}benzoate (19). 18(1.66 g, 4.86 mmol) was treated

with NaH (60% in mineral oil, 0.24 g, 5.83 mmol) and bromo-

diphenylmethane (1.8g, 7.29 mmol) in DMF (5 mL) as described

in the general N-alkylation procedure, and ﬂash chromatography

(10% EtOAc-hexanes) delivered 19 (1.47 g, 59% yield) as a white

solid. ¹H NMR (300 MHz, CDCl₃) δ 1.83-1.99 (m, 2 H), 2.15 (s,

3 H), 2.61-2.74 (m, 4 H), 3.84-3.89 (s 3 H), 6.48 (d, J ) 8.8 Hz,

1 H), 6.76 (dd, J ) 8.7, 2.1 Hz, 1 H), 6.82 (s, 1 H), 7.03-7.09 (m,

4 H), 7.19 (d, J ) 8.2 Hz, 2 H), 7.22-7.24 (m, 1 H), 7.26-7.32

(m, 5 H), 7.38 (d, J ) 1.9 Hz, 1 H), 7.91 (d, J ) 8.2 Hz, 2 H).

Methyl 4-{3-[5-Chloro-1-(diphenylmethyl)-2-formyl-1H-indol-

3-yl]propyl}benzoate (20). To a solution of 19 (1.46 g, 2.87mmol)

in CCl₄(14.5 mL) was added NBS (1.02 g, 5.73 mmol) and benzoyl

peroxide (2 mg). The reaction mixture was heated to reﬂux for

1 h, cooled to room temperature, and ﬁltered, and the solid was

washed with CCl₄. The ﬁltrate was evaporated to afford a brown

residue that was dissolved in acetone (40 mL) and water (4 mL).

Ag₂CO₃(1.75 g, 3.16 mmol) was then added, and the resulting

suspension was stirred overnight. The mixture was ﬁltered through

Celite, the solvent was evaporated under reduced pressure, and the

residue was taken up in H₂O, extracted with EtOAc, washed with

brine, dried (Na₂SO₄), and concentrated. Flash chromatography

(10% EtOAc-hexanes) afforded 20 (1.13 g) in 75% yield. ¹H NMR

(300 MHz, CDCl₃) δ 1.98-2.14 (m, 2 H), 2.76 (t, J ) 7.7 Hz, 2

H), 3.07 (m, 2 H), 3.89 (s, 3 H), 6.61 (d, J ) 9.1 Hz, 1 H), 6.99

(dd, J ) 9.1, 2.2 Hz, 1 H), 7.09-7.14 (m, 4 H), 7.21 (s, 1 H),

7.26-7.31 (m, 7 H), 7.55 (d, J ) 2.2 Hz, 1 H), 7.95 (d, J ) 8.2

Hz, 2 H), 8.21 (s, 1 H), 10.02 (s, 1 H).

3-(4-{[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphe-

nylmethyl)-1H-indol-3-yl]methyl}phenyl)propanoic acid (13).

Hydrolysis of the methyl ester (50 mg, 0.072 mmol) according to

the general procedure afforded the carboxylic acid 13 (32 mg, 65%

yield) as a tan solid. ¹H NMR (300 MHz, DMSO-d₆) δ 2.15-2.26

(m, 2 H), 2.50-2.61 (m, 2 H), 2.64-2.84 (m, 4 H), 3.79 (s, 2 H),

4.03 (s, 2 H), 6.24 (d, J ) 9.1 Hz, 1 H), 6.57 (dd, J ) 8.8, 1.9 Hz,

1 H), 6.85-6.92 (m, 8 H), 7.03-7.12 (m, 6 H), 7.14-7.24 (m,

7 H).

4,4-Diethoxy-N′-hydroxybutanimidamide. A mixture of 4,4-

diethoxybutanenitrile (3.0 g, 19.1 mmol) and hydroxylamine (50

wt % in water, 4.2 g, 63.6 mmol) was stirred for 3 days. The

volatiles were removed under high vacuum to give the hydroxya-

midine in quantitative yield. ¹H NMR (300 MHz, DMSO-d₆) δ

1.12 (t, J ) 7.0 Hz, 6 H), 1.65-1.79 (m, 2 H), 1.93–2.06 (m, 2 H),

3.37-3.51 (m, 2 H), 3.51-3.64 (m, 2 H), 4.46 (t, J ) 5.6 Hz, 1

H), 5.35 (s, 2 H), 8.74 (s, 1 H).

Ethyl [3-(3,3-Diethoxypropyl)-1,2,4-oxadiazol-5-yl]acetate. To

the hydroxyamidine (1.79 g, 9.4 mmol) in THF (30 mL) under

nitrogen was added NaH (400 mg, 60% in mineral oil, 10 mmol).

The mixture was heated to 50 °C for 1 h. The mixture was cooled

to room temperature, and diethyl malonate (4.3 mL, 28.3 mmol)

was added dropwise. The resulting mixture was heated to 85 °C

for 1 h. The mixture was concentrated and puriﬁed by ﬂash

chromatography (10% EtOAc-hexane) to afford the oxadiazole

(1.4 g) in 52% yield. ¹H NMR (300 MHz, DMSO-d₆) δ 0.90 (t, J

) 7.0 Hz, 6 H), 1.00 (t, J ) 7.1 Hz, 3 H), 1.65-1.74 (m, 2 H),

2.53 (t, J ) 7.7 Hz, 2 H), 3.17-3.29 (m, 2 H), 3.32-3.44 (m, 2

H), 3.95 (q, J ) 7.1 Hz, 2 H), 4.04 (s, 2 H), 4.32 (t, J ) 5.5 Hz,

1 H).

(3-{3-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphe-

nylmethyl)-1H-indol-3-yl]propyl}-1,2,4-oxadiazol-5-yl)acetic acid

(15). To a mixture of 7 (90 mg, 0.17 mmol), oxadiazole (54 mg,

0.19 mmol), and Et₃SiH (84 µL, 0.53 mmol) under nitrogen was

added TFA dropwise (41 µL, 0.53 mmol) according to the general

reductive alkylation procedure. The mixture was concentrated and

puriﬁed by preparative TLC to afford indole 14 in 54% yield (65

mg). The ethyl ester intermediate was hydrolyzed according to the

general procedure to afford the title acid 15 (60 mg, 96% yield).

¹H NMR (300 MHz, DMSO-d₆) δ 1.64-1.77 (m, 2 H), 2.37-2.71

(m, 8 H), 3.41 (s, 2 H), 4.09 (s, 2 H), 6.23 (d, J ) 8.8 Hz, 1 H),

6.58 (dd, J ) 8.8, 2.2 Hz, 1 H), 6.72-7.05 (m, 7 H), 7.05-7.25

(m, 9 H), 7.38 (d, J ) 1.9 Hz, 1 H), 7.82 (s, 1 H).

Methyl 4-(3-{5-Chloro-1-(diphenylmethyl)-2-[(E)-2-nitrovi-

nyl]-1H-indol-3-yl}propyl)benzoate (21). To a solution of 20 (0.52

g, 1.0 mmol) in CH₃NO₂(6.2 mL) was added NH₄OAc (0.077 g,

1.0 mmol), and the mixture was heated to reﬂux for 1 h. Additional

NH₄OAc (0.077 g, 1.0 mmol) was then added, and heating at reﬂux

was continued for an additional 1 h. NH₄OAc (0.077 g, 1.0 mmol)

was added again, and the heating continued for a further 1 h. The

reaction mixture was cooled to room temperature, and aqueous

workup was performed followed by ﬂash chromatography (10%

EtOAc-hexanes) to yield the nitro oleﬁn 21 (0.38 g, 68% yield)

as a yellow foam.

Methyl 4-{3-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]propyl}benzoate (22). Zn(Hg) was made by adding

HgCl₂(3.4 g, 7.2 mmol) to a mixture of Zn dust (34.7 g, 530 mmol)

and 5% HCl (38 mL) and stirring this vigorously for 10 min. The

aqueous phase was decanted and washed with 38 mL of 5% HCl.

This solid was added to a mixture of the nitro oleﬁn 21(15 g, 26.6

mmol) in THF (660 mL) and concentrated HCl (65 mL). This

mixture was stirred at room temperature for 1 h, then at reﬂux for

15 min. The reaction mixture was cooled to room temperature and

ﬁltered through Celite. Concentrated aqueous NH₄OH solution (200

mL) was added to the ﬁltrate, the resulting mixture was stirred for

15 min, and THF was removed under reduced pressure. The

aqueous layer was extracted with CH₂Cl₂, and the combined organic

layer was washed with brine, dried (Na₂SO₄), and concentrated to

afford a brown foam that was puriﬁed by column chromatography

(0-2% MeOH-CHCl₃) to isolate the desired amine 22 (6.1 g, 46%

Methyl 3-(4-{2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-

1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}phenyl)propanoate (16).

Using the general reductive alkylation procedure, 7 (220 mg, 0.43

mmol) was reacted with methyl 3-[4-(2-oxoethoxy)phenyl]pro-

panoate⁷⁶(150 mg, 0.65 mmol) to afford the C3 alkylated indole

16 (90 mg, 30% yield).

3-{4-[2-(1-Benzhydryl-2-{2-[(benzylsulfonyl)amino]ethyl}-5-

chloro-1H-indol-3-yl)ethoxy]phenyl}propanoic acid (17). Hy-

drolysis of the methyl ester (90 mg, 0.13 mmol) according to the

general procedure afforded the carboxylic acid 17 (66 mg, 75%

yield), mp 94.8 °C. ¹H NMR (400 MHz, CDCl₃) δ 2.63 (t, J ) 7.3

Hz, 2H), 2.70-2.84 (m, 4H), 2.86 (t, 2H), 3.08 (t, J ) 6.3 Hz,

2H), 4.04 (s, 2H), 4.22 (t, J ) 6.3 Hz, 1H), 4.70 (s, 1H), 6.38-6.54

(d, J ) 9.1 Hz, 1 H), 6.75 (d, J ) 8.6 Hz, 2H), 6.79 (dd, J ) 8.9,

2.1 Hz, 1H), 6.83 (s, 1H), 7.02-7.11 (m, 6H), 7.13-7.25 (m, 5H),

1

yield). H NMR (300 MHz, CDCl₃) δ 1.99 (t, J ) 7.7 Hz, 2 H),

2.69-2.80 (m, 6 H), 2.84 (t, J ) 7.2 Hz, 2 H), 3.85-3.93 (s, 3 H),

3402 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

6.48 (d, J ) 8.8 Hz, 1 H), 6.77 (dd, J ) 8.8, 2.0 Hz, 1 H), 6.89 (s,

1 H), 7.05-7.12 (m, 4 H), 7.23 (s, 1 H), 7.27-7.33 (m, 7 H), 7.41

(d, J ) 2.0 Hz, 2 H), 7.95 (d, J ) 8.3 Hz, 2 H).

mixture was allowed to warm to room temperature and after 1 h

was quenched with aqueous NH₄Cl solution. Aqueous workup and

puriﬁcation via ﬂash chromatography (10% EtOAc/CH₂Cl₂) deliv-

ered 30 (3.31 g, 86% yield) as a white solid. ¹H NMR (400 MHz,

CDCl₃) δ 2.99 (t, J ) 6.3 Hz, 2 H), 3.16-3.25 (m, 2 H), 3.40-3.47

(m, 2 H), 3.65 (q, J ) 6.0 Hz, 2 H), 3.98 (s, 3 H), 6.45 (d, J ) 8.8

Hz, 1 H), 6.76 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.92 (s, 1 H), 7.02-7.08

(m, 4 H), 7.17 (d, J ) 1.8 Hz, 1 H), 7.26-7.34 (m, 6 H), 7.98-8.09

(m, 2 H), 8.18-8.27 (m, 2 H).

Methyl 4-{[2-(5-Chloro-1-(diphenylmethyl)-2-{2-[(methylsul-

fonyl)oxy]ethyl}-1H-indol-3-yl)ethyl]sulfonyl}benzoate (31).

MsCl (0.69 mL, 8.91 mmol) and Et₃N (1.55 mL, 11.1 mmol) were

added to a solution of alcohol 30 (2.62 g, 4.45 mmol) in CH₂Cl₂

(0.02 M) at 0 °C. After 1 h, the reaction mixture was warmed to

room temperature. After 1 h, aqueous workup was performed and

concentration afforded 31 (2.93 g, 86% yield) as a light-yellow

solid. ¹H NMR (400 MHz, CDCl₃) δ 2.82 (s, 3 H), 3.22 (t, J ) 6.3

Hz, 4 H), 3.38-3.46 (m, 2 H), 3.95-3.99 (m, 3 H), 4.01 (t, J )

6.8 Hz, 2 H), 6.48-6.54 (m, 1 H), 6.79-6.85 (m, 1 H), 6.87 (s, 1

H), 7.02-7.09 (m, 4 H), 7.27-7.36 (m, 7 H), 8.01-8.10 (m, 2 H),

8.23 (dd, J ) 8.6, 1.8 Hz, 2 H).

Methyl 4-{3-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]propyl}benzoate (23). The amine

(1.5 g, 2.79 mmol) was reacted with R-toluenesulfonyl chloride

according to the general Schotten-Baumann procedure to afford

sulfonamide 23 (1.62 g, 84% yield). ¹H NMR (300 MHz, CDCl₃)

δ 1.90-2.01 (m, 2 H), 2.67-2.80 (m, 6 H), 2.88-2.96 (m, 2 H),

3.91 (s, 3 H), 4.00 (t, J ) 6.0 Hz, 1 H), 4.03-4.05 (m, 2 H), 6.50

(d, J ) 8.8 Hz, 1 H), 6.81 (dd, J ) 8.8, 2.2 Hz, 1 H), 6.84-6.86

(m, 1 H), 7.04-7.09 (m, 5 H), 7.15 (d, J ) 1.6 Hz, 1 H), 7.17-7.19

(m, 1 H), 7.24-7.26 (m, 2 H), 7.26-7.28 (m, 2 H), 7.30-7.35

(m, 6 H), 7.41 (d, J ) 1.9 Hz, 1 H), 7.96 (d, J ) 8.2 Hz, 2 H).

4-{3-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphe-

nylmethyl)-1H-indol-3-yl]propyl}benzoic Acid (24). Ester 23

(1.59 g, 2.3 mmol) was hydrolyzed using the general procedure to

1

afford the desired product (1.56 g) in 100% yield. H NMR (300

MHz, CDCl₃) δ 1.90-2.02 (m, 2 H), 2.69-2.81 (m, 4 H),

3.73-3.79 (m, 4 H), 4.05 (s, 2 H), 4.10-4.18 (m, 1 H), 6.50 (d, J

) 8.8 Hz, 1 H), 6.81 (dd, J ) 8.8, 2.2 Hz, 1 H), 6.84-6.86 (m, 1

H), 7.03-7.10 (m, 5 H), 7.14-7.16 (m, 1 H), 7.16-7.19 (m, 2 H),

7.25 (s, 1 H), 7.30 (s, 2 H), 7.31-7.36 (m, 6 H), 7.41 (d, J ) 1.9

Hz, 1 H), 8.01 (d, J ) 8.2 Hz, 2 H). HRMS calcd for

[C₄₀H₃₇ClN₂O₄S + H] 677.2235 found 677.224.

2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-1H-in-

dole (26). 2-(5-Chloro-1H-indol-2-yl)ethanol 25⁵⁰(13.7 g, 70.0

mmol) was added to a solution (under N₂) containing tBDMSCl

(22 mL, 84.6 mmol), imidazole (11.9 g, 175.2 mmol), and DMF

(1.8 M). The reaction mixture was stirred overnight, quenched with

saturated aqueous NaHCO₃, and subjected to an aqueous workup

which delivered, after puriﬁcation via ﬂash chromatography (30%

hexanes/CH₂Cl₂), 26 (28.2 g, 95% yield) as a yellow oil.

Methyl 4-({2-[2-(2-Azidoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}sulfonyl)benzoate (32). A mixture of indole

31 (2.89 g, 4.34 mmol), sodium azide (1.43 g, 22.0 mmol), and

DMF (0.05 M) was heated to 60 °C. After 1 h the reaction mixture

was cooled and an aqueous workup was performed to afford 32

1

(2.67 g, 99% yield) as a light-yellow solid. H NMR (400 MHz,

acetone-d₆) δ 3.01 (t, J ) 7.2 Hz, 2 H), 3.04-3.11 (m, 2 H), 3.21

(t, J ) 7.1 Hz, 2 H), 3.48-3.55 (m, 2 H), 3.82 (s, 3 H), 6.48 (d,

J ) 8.6 Hz, 1 H), 6.66 (dd, J ) 9.0, 2.1 Hz, 1 H), 6.96-7.03 (m,

4 H), 7.07 (s, 1 H), 7.16 (d, J ) 1.8 Hz, 1 H), 7.20-7.27 (m, 6 H),

8.01 (d, J ) 8.6 Hz, 2 H), 8.08-8.14 (m, 2 H).

Methyl 4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-

chloro-1H-indol-3-yl]ethyl}thio)benzoate (27). Indole 26 (10.1 g,

23.3 mmol), methyl 4-[(2-oxoethyl)sulfanyl]benzoate⁴¹(18.2 g, 86.6

mmol), TFA (5.4 mL, 70.1 mmol), Et₃SiH (44 mL, 275.5 mmol)

were treated following the general reductive alkylation procedure

to yield, after puriﬁcation via ﬂash chromatography (20% EtOAc/

hexane), 27 (11.5 g, 79% yield) as a yellow solid.

Methyl 4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-

chloro-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}thio)benzoate (28).

Indole 27 (11.6 g, 18.4 mmol), NaH (0.81 g, 20.3 mmol), and

bromodiphenylmethane (8.2 g, 33.2 mmol) were reacted using the

general N-alkylation conditions to afford, after puriﬁcation via ﬂash

chromatography (20% EtOAc/hexanes), 28 (9.5 g, 65% yield) as a

yellow gum. ¹H NMR (400 MHz, CDCl₃) δ 0.98 (s, 9 H),

2.94-3.07 (m, 4 H), 3.16 (t, J ) 7.6 Hz, 2 H), 3.65 (t, J ) 7.3 Hz,

2 H), 3.90 (s, 3 H), 6.39 (d, J ) 8.8 Hz, 1 H), 6.69 (s, 1 H), 6.75

(dd, J ) 8.8, 2.0 Hz, 1 H), 6.92 (d, J ) 7.1 Hz, 3 H), 7.15-7.30

(m, 11 H), 7.30-7.43 (m, 5 H), 7.44-7.54 (m, 3 H), 7.71 (dd, J )

7.7, 1.9 Hz, 1 H), 7.85-7.94 (m, 2 H).

Methyl 4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoate (29).

NMO (6.45 g, 55.1 mmol) was added to a solution containing silyl

ether 28 (7.27 g, 9.15 mmol), CH₃CN (0.1 M), and molecular sieves

(1 g/mmol of benzoate). After 10 min, TPAP (0.39 g, 1.11 mmol)

was added and the mixture was heated to 40 °C. After 1.5 h the

reaction mixture was cooled and ﬁltered. The ﬁltrate was puriﬁed

via ﬂash chromatography (20% EtOAc/hexanes) to deliver 29 (5.30

g, 65% yield) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ

0.98 (s, 9 H), 2.99 (t, J ) 6.9 Hz, 2 H), 3.11-3.18 (m, 2 H),

3.24-3.31 (m, 2 H), 3.64 (t, J ) 6.8 Hz, 2 H), 3.97 (s, 3 H), 6.35

(d, J ) 8.8 Hz, 1 H), 6.65 (s, 1 H), 6.73 (dd, J ) 8.8, 2.0 Hz, 1 H),

6.87 (d, J ) 7.3 Hz, 4 H), 7.10 (d, J ) 2.0 Hz, 1 H), 7.16-7.28

(m, 9 H), 7.33-7.39 (m, 2 H), 7.42-7.51 (m, 4 H), 7.96 (d, J )

8.6 Hz, 3 H), 8.19 (d, J ) 8.6 Hz, 2 H).

Methyl 4-({2-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}sulfonyl)benzoate (33). Azide 32 (2.64 g, 4.31

mmol), PPh₃(2.30 g, 8.70 mmol), and THF (0.1 M) were placed

together under N₂and stirred overnight. H₂O (1 mL/mmol benzoate)

was added, and reaction mixture was stirred overnight. The solution

was concentrated and puriﬁed via ﬂash chromatography (gradient

elution 75% EtOAc/hexanes followed by 5% MeOH/CH₂Cl₂) to

afford 33 (2.52 g, 99% yield) as a light-yellow solid. ¹H NMR

(400 MHz, CDCl₃) δ 2.75 (d, J ) 6.5 Hz, 2 H), 2.83-2.92 (m, 2

H), 3.14-3.26 (m, 2 H), 3.38-3.49 (m, 2 H), 3.98 (s, 3 H), 6.47

(d, J ) 8.8 Hz, 1 H), 6.76 (dd, J ) 8.8, 2.3 Hz, 1 H), 6.88 (s, 1 H),

7.14 (d, J ) 2.0 Hz, 1 H), 7.22-7.34 (m, 5 H), 7.46 (d, J ) 3.0

Hz, 1 H), 7.50 (m, 5 H), 7.62-7.72 (m, 1 H), 8.05 (d, J ) 8.6 Hz,

2 H), 8.24 (d, J ) 8.3 Hz, 2 H).

Methyl 4-({2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoate (34). R-

Toluenesulfonyl chloride (0.094 g, 0.49 mmol) and amine 33 (0.14

g,0.25mmol),werereactedfollowingthegeneralSchotten-Baumann

procedure. After 2 h, aqueous workup and puriﬁcation by silica

gel preparatory plate (3% MeOH in CH₂Cl₂) delivered 34 (0.17 g,

94% yield). ¹H NMR (400 MHz, CDCl₃) δ 2.87 (t, J ) 6.6 Hz, 2

H), 2.95 (t, J ) 7.1 Hz, 2 H), 3.13-3.21 (m, 2 H), 3.34-3.41 (m,

2 H), 3.97 (s, 3 H), 4.08 (s, 2 H), 4.34 (t, J ) 6.3 Hz, 1 H), 6.46

(d, J ) 8.8 Hz, 1 H), 6.78 (dd, J ) 8.9, 2.14 Hz, 1 H), 6.81 (s, 1

H), 7.01-7.07 (m, 4 H), 7.18-7.23 (m, 3 H), 7.27-7.33 (m, 9 H),

8.03 (d, J ) 8.6 Hz, 2 H), 8.22 (d, J ) 8.6 Hz, 2 H).

4-{[2-(1-Benzhydryl-2-{2-[(benzylsulfonyl)amino]ethyl}-5-

chloro-1H-indol-3-yl)ethyl]sulfonyl}benzoic Acid (35). Ester 34

(0.13 g, 0.18 mmol) was hydrolyzed using the general procedure

to afford the desired product 35 (0.12 g, 92% yield), mp 97 °C. ¹H

NMR (400 MHz, CDCl₃) δ 2.87 (t, J ) 6.6 Hz, 2H), 2.95 (d, J )

6.8 Hz, 2H), 3.13-3.24 (m, 2H), 3.34-3.44 (m, 2H), 4.09 (s, 2H),

4.43 (t, J ) 6.1 Hz, 1H), 6.47 (d, J ) 8.8 Hz, 1H), 6.78 (dd, J )

9.1, 2.1 Hz, 1H), 6.81 (s, 1H), 7.05 (dd, J ) 6.6, 2.8 Hz, 4H),

7.19-7.23 (m, 3H), 7.27-7.34 (m, 9H), 8.06 (d, J ) 8.6 Hz, 2H),

8.24 (d, J ) 8.3 Hz, 2H). HRMS calcd [C₃₉H₃₅ClN₂O₆S₂+H]

725.155 23; found 725.154 37.

Methyl 4-({2-[5-Chloro-1-(diphenylmethyl)-2-(2-hydroxyethyl)-

1H-indol-3-yl]ethyl}sulfonyl)benzoate (30). TBAF (7.9 mL, 7.9

mmol, 1.0 M solution in THF) was added to a solution of silyl

ether 29 (5.42 g, 6.56 mmol) and THF (0.1 M) at 0 °C. The reaction

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3403

3-(2-Bromoethyl)-2-(2-{[tert-butyl(diphenyl)silyl]oxy}ethyl)-

5-chloro-1-(diphenylmethyl)-1H-indole (37). To a solution of

alcohol 36 (1.085 g, 1.7 mmol) in CH₂Cl₂(0.08 M) was added

1,3-bis(diphenylphosphino)propane (0.52 g, 1.3 mmol). The solution

was cooled to 0 °C under N₂, and CBr₄(0.69 g, 2.1 mmol) was

added. The mixture was warmed to room temperature over 2 h,

concentrated, and puriﬁed via ﬂash chromatography (40% CH₂Cl₂/

hexanes) to give 37 (0.33 g, 28%). ¹H NMR (400 MHz, CDCl₃) δ

1.02 (m, 9 H), 3.02-3.12 (m, 3 H), 3.18 (t, J ) 7.9 Hz, 1 H), 3.46

(t, J ) 7.9 Hz, 1 H), 3.60 (t, J ) 7.8 Hz, 1 H), 3.66 (t, J ) 7.1 Hz,

2 H), 6.39 (d, J ) 8.8 Hz, 1 H), 6.71 (s, 1 H), 6.73-6.78 (m, 1 H),

6.92 (d, J ) 7.1 Hz, 4 H), 7.15-7.30 (m, 8 H), 7.30-7.40 (m, 4

H), 7.43 (d, J ) 2.0 Hz, 1 H), 7.48-7.55 (m, 4 H).

Methyl 3-[4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-

chloro-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}thio)phenyl]propano-

ate (38). To a solution of bromide 37 (3.6 g, 5.1 mmol) in DMF

(0.1 M) were added methyl 3-(4-mercaptophenyl)propanoate⁴¹(1.51

g, 7.7 mmol) and K₂CO₃(1.1 g, 7.7 mmol). After 2 h, aqueous

workup followed by puriﬁcation by ﬂash chromatography (CH₂Cl₂)

afforded 38 (3.37 g, 80% yield).

Methyl 3-[4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-

chloro-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]-

propanoate (39). NMO (2.0 g, 16.4 mmol) was added to a solution

containing silyl ether 38 (3.35 g, 4.1 mmol), CH₃CN (0.1 M), and

molecular sieves (1 g/mmol benzoate). After 10 min, TPAP (0.75

g, 0.20 mmol) was added and the mixture was heated to 40 °C.

After 1.5 h the reaction mixture was cooled, and the ﬁltrate was

collected and puriﬁed via ﬂash chromatography (gradient elution

0-1% EtOAc-CH₂Cl₂) to deliver 39 (1.53 g, 44% yield) as a white

foam.

Methyl 3-[4-({2-[5-Chloro-1-(diphenylmethyl)-2-(2-hydrox-

yethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (40).

TBAF (2.1 mL, 2.1 mmol, 1.0 M solution in THF) was added to

a solution of silyl ether 39 (1.5 g, 1.8 mmol) and THF (0.1 M) at

0 °C. The reaction mixture was allowed to warm to room

temperature, and after 1 h it was quenched with aqueous NH₄Cl

solution. Aqueous workup and puriﬁcation via ﬂash chromatography

(gradient elution 10-25% EtOAc-CH₂Cl₂) delivered 40 (1.0 g,

90% yield) as a white foam. ¹H NMR (400 MHz, CDCl₃) δ

2.64-2.72 (m, 2 H), 2.97 (t, J ) 6.5 Hz, 2 H), 3.02-3.09 (m, 2

H), 3.12-3.20 (m, 2 H), 3.34-3.41 (m, 2 H), 3.60-3.65 (m, 2 H),

3.67 (s, 3 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.71-6.79 (m, 2 H), 6.92

(s, 1 H), 7.03-7.08 (m, 3 H), 7.10-7.17 (m, 2 H), 7.27-7.33 (m,

5 H), 7.41-7.45 (m, 2 H), 7.89 (d, J ) 8.3 Hz, 2 H).

Methyl 3-(4-{[2-(5-Chloro-1-(diphenylmethyl)-2-{2-[(methylsul-

fonyl)oxy]ethyl}-1H-indol-3-yl)ethyl]sulfonyl}phenyl)propanoate

(41). MsCl (0.15 mL, 2.0 mmol) and Et₃N (0.35 mL, 2.5 mmol)

were added to a solution of alcohol 40 (0.615 g, 1.0 mmol) in

CH₂Cl₂(0.02 M) at 0 °C under N₂. After 1 h the reaction mixture

was warmed to room temperature and stirred for 1 h. Aqueous

workup afforded 41 (0.730 g) in quantitative yield.

Methyl 3-[4-({2-[2-(2-Azidoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (42). To mesy-

late 41 (0.228 g, 0.33 mmol) in DMF (0.03 M) was added NaN₃

(0.065 g, 1.0 mmol). The mixture was heated to 60 °C for 2 h and

cooled and an aqueous workup was performed to afford 42 (0.250

g) in quantitative yield. ¹H NMR (400 MHz, CDCl₃) δ 2.63-2.71

(m, 2 H), 2.92-2.97 (m, 2 H), 3.03-3.10 (m, 2 H), 3.12-3.21

(m, 4 H), 3.34-3.41 (m, 2 H), 3.67 (s, 3 H), 6.49 (d, J ) 8.8 Hz,

1 H), 6.80 (dd, J ) 8.8, 2.0 Hz, 1 H), 6.87 (s, 1 H), 7.02-7.09 (m,

4 H), 7.10-7.15 (m, 2 H), 7.29-7.34 (m, 5 H), 7.41-7.46 (m, 2

H), 7.88-7.92 (m, 2 H).

Methyl 3-[4-({2-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (43). Azide 42

(0.25 g, 0.39 mmol), PPh₃(0.113 g, 0.43 mmol), and THF (0.1 M)

were stirred overnight. Water (1 mL/mmol benzoate) was added,

and reaction mixture was again stirred overnight. The solution was

concentrated and puriﬁed via ﬂash chromatography (4%

MeOH-CH₂Cl₂) to afford 43 (0.17 g, 71% yield) as a white

foam.¹H NMR (400 MHz, CDCl₃) δ 2.64-2.71 (m, 2 H), 2.73

(t, J ) 6.9 Hz, 2 H), 2.87 (t, J ) 7.1 Hz, 2 H), 3.03-3.09 (m,

2 H), 3.13-3.20 (m, 2 H), 3.33-3.40 (m, 2 H), 3.67 (s, 3 H),

6.46 (d, J ) 8.8 Hz, 1 H), 6.75 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.88

(s, 1 H), 7.01-7.07 (m, 4 H), 7.09 (d, J ) 2.0 Hz, 1 H),

7.27-7.32 (m, 6 H), 7.43 (d, J ) 8.6 Hz, 2 H), 7.90 (d, J ) 8.3

Hz, 2 H).

Methyl 3-[4-({2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate

(44). Amine 43 (0.100 g, 0.16 mmol), R-toluenesulfonyl chloride

(0.035 g, 0.18 mmol), and saturated aqueous NaHCO₃were reacted

according to the general Schotten-Baumann procedure. Aqueous

workup and puriﬁcation by chromatography (2% MeOH/CH₂Cl₂)

delivered sulfonamide 44 (0.116 g, 94% yield). ¹H NMR (400 MHz,

CDCl₃) δ 2.67 (t, J ) 7.6 Hz, 2 H), 2.80-2.96 (m, 4 H), 3.04 (t,

J ) 7.6 Hz, 2 H), 3.08-3.14 (m, 2 H), 3.28-3.35 (m, 2 H), 3.66

(s, 3 H), 4.08 (s, 2 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.72 (dd, J ) 7.4,

1.9 Hz, 1 H), 6.77 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.80-6.84 (m, 1 H),

7.01-7.07 (m, 4 H), 7.16-7.20 (m, 2 H), 7.20-7.24 (m, 2 H),

7.28-7.34 (m, 7 H), 7.40 (d, J ) 8.3 Hz, 2 H), 7.87 (d, J ) 8.3

Hz, 2 H).

3-[4-({2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphenyl-

methyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoic acid (45).

Ester 44 (0.087 g, 0.11 mmol) was hydrolyzed using the general

1

procedure to afford 45 (0.079 g, 92% yield), mp 108–110 °C. H

NMR (400 MHz, CDCl₃) δ 2.60 (s, 4H), 2.75 (d, J ) 6.1 Hz, 2H),

2.81-2.93 (m, 2H), 2.99 (t, J ) 6.2 Hz, 2H), 3.18-3.31 (m, 2 H),

3.98-4.15 (m, 2H), 6.37 (d, J ) 8.8 Hz, 1H), 6.71 (s, 1H),

6.73-6.82 (m, 2H), 6.91-7.05 (m, 4H), 7.07-7.32 (m, 10H), 7.35

(d, J ) 1.5 Hz, 1H), 7.41 (d, J ) 7.8 Hz, 2H), 7.85 (d, J ) 8.1 Hz,

2H). HRMS calcd [C₄₁H₃₉ClN₂O₆S₂+ H], 755.201 08; found

755.202 01.

[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-1-(diphe-

nylmethyl)-1H-indol-3-yl]acetaldehyde (46). To a solution of

oxalyl chloride (0.37 mL, 4.3 mmol) in CH₂Cl₂(10 mL) at –78 °C

was added DMSO (0.66 mL, 9.3 mmol) dropwise. After 5 min, a

solution of 2-{1-benzhydryl-2-[2-(tert-butyldiphenylsilanyloxy)ethyl]-

5-chloro-1H-indol-3-yl}ethanol 36⁴⁴(2.50 g, 3.9 mmol) in CH₂Cl₂

(8 mL) was added. After 40 min, iPr₂NEt (3.38 mL, 19.4 mmol)

was added. The reaction mixture was then subjected to an aqueous

workup, and the resulting product was used without further

puriﬁcation. ¹H NMR (400 MHz, acetone-d₆) δ 0.85 (s, 9 H), 3.11

(t, J ) 7.0 Hz, 2 H), 3.58 (t, J ) 7.0 Hz, 2 H), 3.71 (d, J ) 2.3 Hz,

2 H), 6.45 (d, J ) 9.1 Hz, 1 H), 6.68 (dd, J ) 8.8, 2.3 Hz, 1 H),

6.87-6.94 (m, 6 H), 7.12-7.20 (m, 10 H), 7.26 (d, J ) 7.3 Hz, 2

H), 7.36 (d, J ) 2.3 Hz, 4 H), 9.48 (t, J ) 2.3 Hz, 1 H).

Methyl 4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}amino)benzoate (47). To a

solution of aldehyde 46 (3.9 mmol) in 1,2-dichloroethane (39 mL)

at 0 °C were added methyl 4-aminobenzoate (0.65 g, 4.3 mmol),

acetic acid (1.33 mL), and NaBH(OAc)₃(2.46 g, 11.6 mmol). The

reaction mixture was allowed to warm to room temperature

overnight and then subjected to an aqueous workup. The product

was used without further puriﬁcation. ¹H NMR (400 MHz, acetone-

d₆) δ 1.09 (s, 9 H), 3.21 (t, J ) 7.2 Hz, 2 H), 3.32 (t, J ) 7.1 Hz,

2 H), 3.57-3.64 (m, 2 H), 3.79 (t, J ) 7.2 Hz, 2 H), 3.91 (s, 3 H),

6.66-6.73 (m, 3 H), 6.90 (dd, J ) 8.8, 2.27 Hz, 1 H), 7.08-7.14

(m, 5 H), 7.37-7.45 (m, 10 H), 7.49-7.55 (m, 2 H), 7.63-7.68

(m, 4 H), 7.71 (d, J ) 2.0 Hz, 1 H), 7.84-7.89 (m, 2 H).

Methyl 4-({2-[5-Chloro-1-(diphenylmethyl)-2-(2-hydroxyethyl)-

1H-indol-3-yl]ethyl}amino)benzoate (48). To silyl ether 47 (3.9

mmol) in THF (25 mL) at 0 °C was added a mixture of HOAc/

TBAF (1 M in THF) (2.3 mL/5.8 mL), and the reaction mixture

was allowed to stir at room temperature for 18 h. Aqueous workup

followed by trituration (5% EtOAc/hexanes) afforded 48 (1.64 g,

1

92% yield, over three steps) as an off-white solid. H NMR (400

MHz, acetone-d₆) δ 3.00 (t, J ) 7.0 Hz, 2 H), 3.31-3.37 (m, 4 H),

3.40 (t, J ) 7.2 Hz, 2 H), 3.64 (s, 3 H), 6.41 (d, J ) 8.8 Hz, 1 H),

6.51 (d, J ) 8.8 Hz, 2 H), 6.62 (dd, J ) 8.8, 2.0 Hz, 1 H), 7.03

(dd, J ) 7.1, 2.0 Hz, 4 H), 7.11 (s, 1 H), 7.20-7.26 (m, 6 H), 7.45

(d, J ) 2.0 Hz, 1 H), 7.61 (d, J ) 9.1 Hz, 2 H).

3404 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

Methyl 4-({2-[2-(2-Azidoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}amino)benzoate (52). To a solution of alcohol

48 (1.64 g, 3.1 mmol) in CH₂Cl₂at 0 °C were added Et₃N (0.64

mL, 4.6 mmol) and MsCl (0.28 mL, 3.6 mmol). After 30 min,

aqueous workup afforded the crude mesylate 51 (1.70 g, 90% yield)

as an off-white solid. A solution of the crude mesylate (1.70 g, 2.8

mmol) and NaN₃(89 mg, 13.8 mmol) in DMF (14 mL) was stirred

at 80 °C for 6 h. An aqueous workup followed by ﬂash chroma-

tography (gradient elution 15-25% EtOAc-hexanes) afforded 49

(813 mg, 52% yield). ¹H NMR (400 MHz, acetone-d₆) δ 2.92-3.01

(m, 4 H), 3.15 (t, J ) 7.0 Hz, 2 H), 3.34-3.44 (m, 2 H), 3.60 (s,

3 H), 6.41-6.49 (m, 3 H), 6.64 (dd, J ) 8.8, 2.27 Hz, 1 H),

6.93-6.99 (m, 4 H), 7.02 (s, 1 H), 7.15-7.23 (m, 6 H), 7.44 (d, J

) 1.5 Hz, 1 H), 7.54-7.60 (m, 2 H).

2 H), 3.97-4.00 (m, 2 H), 4.01 (s, 3 H), 6.73 (d, J ) 8.8 Hz, 1 H),

6.91-6.98 (m, 3 H), 7.36 (dd, J ) 7.2, 2.4 Hz, 4 H), 7.44 (s, 1 H),

7.53-7.60 (m, 7 H), 8.01 (d, J ) 9.4 Hz, 2 H).

Methyl 4-[{2-[2-(2-Azidoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}(methyl)amino]benzoate (55). Alcohol 50

(1.20 mmol), Et₃N (0.25 mL, 1.44 mmol), and MsCl (0.11 mL,

1.2 mmol) were reacted using the procedure for 51 to afford the

mesylate 54. The crude mesylate 54 (1.2 mmol) was displaced with

NaN₃(102 mg, 1.56 mmol) as described for 52. Purifcation by

ﬂash chromatography (gradient elution 15–20% EtOAc/hexanes)

afforded 55 (426 mg, 61% yield).

Methyl 4-[{2-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}(methyl)amino]benzoate (56). A solution of

azide 55 (410 mg, 0.71 mmol) and 10% Pd/C (155 mg) in MeOH/

CH₂Cl₂(7 mL/1 mL) was stirred under H₂atmosphere (1 atm) for

2 h. The reaction mixture was ﬁltered through Celite and rinsed

with MeOH and CH₂Cl₂. Flash chromatography (gradient elution

with CH₂Cl₂to 8% MeOH/CH₂Cl₂) gave 56 (305 mg, 78% yield).

¹H NMR (400 MHz, acetone-d₆) δ 2.92 (s, 3 H), 3.05-3.15 (m, 4

H), 3.28 (t, J ) 7.3 Hz, 2 H), 3.77 (s, 3 H), 3.80 (t, J ) 6.8 Hz, 2

H), 6.61 (d, J ) 8.8 Hz, 1 H), 6.65-6.69 (m, 2 H), 6.80 (dd, J )

8.8, 2.3 Hz, 1 H), 7.11 (dd, J ) 7.1, 1.8 Hz, 4 H), 7.15 (s, 1 H),

7.30-7.38 (m, 6 H), 7.56 (d, J ) 1.8 Hz, 1 H), 7.75-7.80 (m,

2 H).

Methyl 4-({2-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}amino)benzoate (53). To a solution of azide

52 (400 mg, 0.7 mmol) in THF (4 mL) at 0 °C was added Ph₃P

(223 mg, 0.9 mmol) in portions. The reaction mixture was stirred

at room temperature for 11 h and then at 35 °C for 4 h before

water (50 uL) was added. The reaction mixture was stirred

overnight, and aqueous workup and puriﬁcation by ﬂash column

chromatography (EtOAc to 20% MeOH/EtOAc with 1% Et₃N)

1

afforded 50 (201 mg, 53% yield) as a solid. H NMR (400 MHz,

acetone-d₆) δ 2.97 (t, J ) 7.1 Hz, 2 H), 3.06 (t, J ) 6.6 Hz, 2 H),

3.23 (t, J ) 6.4 Hz, 2 H), 3.41 (t, J ) 7.1 Hz, 2 H), 3.64 (s, 3 H),

6.38 (d, J ) 8.8 Hz, 1 H), 6.50 (m, 2 H), 6.60 (dd, J ) 8.8, 2.3 Hz,

1 H), 6.93-7.05 (m, 4 H), 7.16-7.27 (m, 6 H), 7.33 (s, 1 H), 7.43

(d, J ) 2.3 Hz, 1 H), 7.60 (m, 2 H).

Methyl 4-({2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-

(diphenylmethyl)-1H-indol-3-yl]ethyl}amino)benzoate (57). To

amine 53 (69 mg, 0.13 mmol) was added R-toluenesulfonyl chloride

(30 mg, 0.16 mmol) according to the general Schotten-Baumann

procedure. Flash chromatography (gradient elution 20-40%

EtOAc-hexanes) afforded 57 (64 mg, 72% yield). ¹H NMR (400

MHz, acetone-d₆) δ 2.91-3.03 (m, 6 H), 3.37 (q, J ) 6.1 Hz, 2

H), 3.64 (s, 3 H), 4.06 (s, 2 H), 6.41 (d, J ) 8.8 Hz, 1 H), 6.47-6.51

(m, 2 H), 6.64 (dd, J ) 8.8, 2.3 Hz, 1 H), 6.96 (s, 1 H), 6.98-7.04

(m, 4 H), 7.12-7.19 (m, 5 H), 7.20-7.26 (m, 6 H), 7.45 (d, J )

1.8 Hz, 2 H), 7.58-7.64 (m, 2 H).

4-[{2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphenyl-

methyl)-1H-indol-3-yl]ethyl}(methyl)amino]benzoic Acid (59).

To amine 56 (61 mg, 0.11 mmol) was added R-toluenesulfonyl

chloride according to the general Schotten-Baumann procedure.

Flash chromatography (20-40% EtOAc/hexanes) afforded 59 (65

mg, 83% yield). ¹H NMR (400 MHz, acetone-d₆) δ 2.82 (s, 3 H),

2.90-2.99 (m, 6 H), 3.62 (t, J ) 6.9 Hz, 2 H), 3.66 (s, 3 H), 4.03

(s, 2 H), 6.42 (d, J ) 8.8 Hz, 1 H), 6.50-6.55 (m, 2 H), 6.62-6.68

(m, 1 H), 6.93 (s, 1 H), 6.97-7.02 (m, 4 H), 7.10-7.17 (m, 5 H),

7.21-7.27 (m, 6 H), 7.41 (d, J ) 2.0 Hz, 1 H), 7.62-7.68 (m,

2 H).

4-[{2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphenyl-

methyl)-1H-indol-3-yl]ethyl}(methyl)amino]benzoic Acid (60).

Ester 59 (62 mg, 0.09 mmol) was hydrolyzed according to the

general procedure to afford 60 (55 mg, 91% yield) as a white solid.

¹H NMR (400 MHz, acetone-d₆) δ 2.90 (s, 3 H), 2.97-3.06 (m, 6

H), 3.68 (t, J ) 6.8 Hz, 2 H), 4.10 (s, 2 H), 6.48 (d, J ) 8.8 Hz,

1 H), 6.60 (d, J ) 9.3 Hz, 2 H), 6.72 (dd, J ) 8.8, 2.0 Hz, 2 H),

7.00 (s, 1 H), 7.04-7.09 (m, 4 H), 7.18-7.24 (m, 5 H), 7.26-7.34

(m, 6 H), 7.48 (d, J ) 2.0 Hz, 1 H), 7.73-7.78 (m, 2 H). HRMS

calcd [C₄₀H₃₈ClN₃O₄S + H] 692.234 43; found 692.233 74.

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-nitroben-

zyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (80). Meth-

yl 4-{2-[2-(2-aminoethyl)-1-benzhydryl-5-chloro-1H-indol-3-yl]-

ethoxy}benzoate amine 79⁴⁴(1.0 g, 1.9 mmol) and (2-

nitrophenyl)methanesulfonyl chloride (0.43 g, 1.9 mmol) were

reacted according to the general Schotten-Baumann procedure.

Flash chromatography (gradient elution with 0-1% MeOH in

CH₂Cl₂) afforded the sulfonamide 80 (1.13 g, 82% yield) as a

yellow foam. ¹H NMR (300 MHz, CDCl₃) δ 2.80-2.98 (m, 2 H),

2.99-3.11 (m, 2 H), 3.19 (t, J ) 6.6 Hz, 2 H), 3.88 (s, 3 H), 4.20

(appar t, J ) 6.5 Hz, 3 H), 4.64 (s, 2 H), 6.51 (d, J ) 9.1 Hz, 1 H),

6.74-6.91 (m, 4 H), 7.00-7.16 (m, 4 H), 7.28-7.38 (m, 6 H),

7.40-7.62 (m, 4 H), 7.88-8.04 (m, 3 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-nitrobenzyl)sulfo-

nyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic acid (81). Ester

80 (1.13 g, 1.50 mmol) was hydrolyzed according to the general

procedure to afford 81 (0.95 g, 85% yield) as a pale-yellow foam.

¹H NMR (300 MHz, DMSO-d₆) δ 3.02 (s, 4 H), 3.17 (t, J ) 6.3

Hz, 2 H), 4.22 (t, J ) 6.5 Hz, 2 H), 4.76 (s, 2 H), 6.47 (d, J ) 8.8

Hz, 1 H), 6.81 (dd, J ) 9.1, 2.2 Hz, 1 H), 6.98 (d, J ) 8.8 Hz, 2

H), 7.02-7.21 (m, 5 H), 7.29-7.43 (m, 6 H), 7.52 (dd, J ) 7.1,

1.9 Hz, 1 H), 7.54-7.72 (m, 4 H), 7.86 (d, J ) 8.8 Hz, 2 H), 7.98

(dd, J ) 7.3, 2.1 Hz, 1 H). HRMS calcd for [C₃₉H₃₄ClN₃O₇.S +

H] 724.1879; found 724.1877.

4-({2-[2-{2-[(Benzylsulfonyl)amino]ethyl}-5-chloro-1-(diphe-

nylmethyl)-1H-indol-3-yl]ethyl}amino)benzoic Acid (58). Ester

57 (62 mg, 0.1 mmol) was hydrolyzed according to the general

1

procedure to afford 58 (53 mg, 87% yield) as a white solid. H

NMR (400 MHz, acetone-d₆) δ 2.97-3.10 (m, 6 H), 3.45 (t, J )

7.2 Hz, 2 H), 4.15 (s, 2 H), 6.49 (d, J ) 8.8 Hz, 1 H), 6.56-6.61

(m, 2 H), 6.72 (dd, J ) 8.8, 2.3 Hz, 1 H), 7.05 (s, 1 H), 7.07-7.11

(m, 4 H), 7.20-7.27 (m, 5 H), 7.29-7.36 (m, 6 H), 7.54 (d, J )

2.3 Hz, 1 H), 7.71-7.75 (m, 2 H). HRMS calcd [C₃₉H₃₆ClN₃O₄S

+ H] 678.218 78; found 678.2178.

Methyl 4-[{2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}(methyl)amino]benzoate

(49). To aldehyde 46 [2-(2-{[tert-butyl(diphenyl)silyl]oxy}ethyl)-

5-chloro-1-(diphenylmethyl)-1H-indol-3-yl]acetaldehyde (1.50 g,

1.3 mmol) were added methyl 4-(methylamino)benzoate (0.42 g,

2.56 mmol), acetic acid (0.8 mL), and NaBH(OAc)₃(1.48 g, 6.99

mmol) according to the procedure described for 47. Aqueous

workup and puriﬁcation via ﬂash chromatography (gradient elution

8-20% EtOAc-hexane) generated 49 (1.0 g, 54% yield from

alcohol 36). ¹H NMR (400 MHz, acetone-d₆) δ 0.91 (s, 9 H), 2.83

(s, 3 H), 3.05-3.11 (m, 4 H), 3.57 (t, J ) 7.0 Hz, 2 H), 3.73 (t, J

) 7.0 Hz, 2 H), 3.77 (s, 3 H), 6.51 (d, J ) 8.8 Hz, 1 H), 6.60-6.65

(m, 1 H), 6.75 (dd, J ) 8.8, 2.3 Hz, 1 H), 6.89 (s, 1 H), 6.92-6.97

(m, 4 H), 7.20-7.28 (m, 11 H), 7.33-7.39 (m, 2 H), 7.43-7.48

(m, 4 H), 7.53 (d, J ) 2.0 Hz, 1 H), 7.77 (d, J ) 9.1 Hz, 2 H).

Methyl 4-[{2-[5-Chloro-1-(diphenylmethyl)-2-(2-hydroxyethyl)-

1H-indol-3-yl]ethyl}(methyl)amino]benzoate (50). To silyl ether

49 (0.99 g, 1.25 mmol) in THF (9 mL) at 0 °C was added a mixture

of HOAc/TBAF (1.0 M in THF) (2.3 mL/5.8 mL) according to the

procedure used for 48. The resulting alcohol 49 was used without

puriﬁcation. ¹H NMR (400 MHz, acetone-d₆) δ 3.16 (s, 3 H), 3.26

(t, J ) 6.7 Hz, 2 H), 3.31 (t, J ) 6.7 Hz, 2 H), 3.92 (t, J ) 6.4 Hz,

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3405

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(3-nitrobenzyl)-

sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (82). 3-Ni-

trophenyl)methanesulfonyl chloride was reacted with amine 79⁴⁴

(0.30 g, 0.57 mmol) using the general Schotten-Baumann proce-

dure. Flash chromatography (20% EtOAc-hexanes) afforded 82

(120 mg, 29% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 2.98-3.06

(m, 2 H), 3.05-3.13 (m, 2 H), 3.17 (t, J ) 7.1 Hz, 2 H), 3.80 (s,

3 H), 4.23 (t, J ) 6.6 Hz, 2 H), 4.52 (s, 2 H), 6.45 (d, J ) 9.1 Hz,

1 H), 6.80 (dd, J ) 8.9, 2.1 Hz, 1 H), 7.00 (d, J ) 8.8 Hz, 2 H),

7.03-7.12 (m, 5 H), 7.31-7.41 (m, 6 H), 7.50 (t, J ) 5.2 Hz, 1

H), 7.59 (t, J ) 7.8 Hz, 1 H), 7.67 (d, J ) 1.9 Hz, 1 H), 7.74 (d,

J ) 8.0 Hz, 1 H), 7.87 (d, J ) 9.1 Hz, 2 H), 8.16-8.25 (m, 2 H).

Methyl 4-{2-[5-Chloro-2-(2-{[(3-cyanobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (88). 3-Bro-

momethylbenzamide (3.10 g, 18.3 mmol)) was reacted ﬁrst with

sodium sulﬁte to yield sodium salt 64 and then with thionyl chloride

to generate 70 as in the general sulfonyl chloride synthesis A. The

crude sulfonyl chloride was reacted with amine 79⁴⁴(0.085 g, 0.15

mmol) according to the Schotten-Baumann procedure to afford

the sulfonamide 88 as a gum. ¹H NMR (300 Hz, CDCl₃) δ

2.85-2.95 (m, 2 H), 3.05-3.15 (m, 2 H), 3.15–3.25 (m, 2 H), 3.88

(s, 3 H), 3.95-4.05 (m, 2 H), 4.15-4.30 (m, 2 H), 6.55 (d, J )

9.0 Hz, 1 H), 6.80-6.89 (m, 4 H), 6.90 (s, 1 H), 7.00-7.15 (m, 4

H), 7.25-7.50 (m, 9 H), 7.60 (d, J ) 7.2 Hz, 1 H), 7.95 (d, J )

8.2 Hz, 2 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(3-nitrobenzyl)sulfo-

nyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (83). Ester

82 (60 mg, 0.20 mmol) was hydrolyzed according to the general

4-{2-[5-Chloro-2-(2-{[(3-cyanobenzyl)sulfonyl]amino}ethyl)-1-(di-

phenylmethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (89). Ester 88

was hydrolyzed according to the general procedure to afford the

title acid (90 mg, 81% overall yield from the amine) as a white

1

procedure to afford 83 (55 mg, 94% yield). H NMR (300 MHz,

DMSO-d₆) δ 2.98-3.06 (m, 2 H), 3.05-3.13 (m, 2 H), 3.17 (t, J

) 5.8 Hz, 2 H), 4.22 (t, J ) 6.5 Hz, 2 H), 4.52 (s, 2 H), 6.45 (d,

J ) 9.1 Hz, 1 H), 6.80 (dd, J ) 8.6, 2.1 Hz, 1 H), 6.98 (d, J ) 9.1

Hz, 2 H), 7.05-7.11 (m, 4 H), 7.31-7.41 (m, 5 H), 7.50 (t, J )

5.6 Hz, 1 H), 7.59 (t, J ) 7.8 Hz, 1 H), 7.66 (d, J ) 1.9 Hz, 1 H),

7.74 (d, J ) 8.2 Hz, 1 H), 7.85 (d, J ) 8.8 Hz, 2 H), 8.16-8.25

(m, 2 H). HRMS calcd for [C₃₉H₃₄ClN₃O₇S + H] 724.1879; found

724.1885.

1

solid. H NMR (400 Hz, DMSO-d₆) δ 2.95-3.10 (m, 4 H), 3.17

(t, J ) 6.5 Hz, 2 H), 4.22 (t, J ) 6.5 Hz, 2 H), 4.39 (s, 2 H), 6.47

(d, J ) 8.9 Hz, 1 H), 6.81 (dd, J ) 8.9, 2.2 Hz, 1 H), 6.96 (d, J )

8.8 Hz, 2 H), 7.05–7.15 (m, 6 H), 7.30-7.40 (m, 6 H), 7.50 (t, J

) 5.9 Hz, 1 H), 7.61 (d, J ) 7.9 Hz, 1 H), 7.66 (d, J ) 2.1 Hz, 1

H), 7.74 (s, 1 H), 7.79 (d, J ) 7.7 Hz, 1 H), 7.90 (d, J ) 8.8 Hz,

2 H), 12.60 (br s, 1 H). HRMS calcd [C₄₀H₃₃ClN₃O₅S – H]

702.1834; found 702.1833. Anal. (C₄₀H₃₄ClN₃O₅S · 0.7H₂O) C,

H, N.

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(4-nitrobenzyl)-

sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (84). (4-Ni-

trophenyl)methanesulfonyl chloride was reacted with amine 79⁴⁴

(0.43 g, 0.80 mmol) using the general Schotten-Baumann proce-

dure. Flash chromatography (20% EtOAc-hexanes) afforded the

sulfonamide 84 (150 mg, 25% yield). ¹H NMR (300 MHz, DMSO-

d₆) δ 2.97-3.13 (m, 4 H), 3.18 (t, J ) 6.6 Hz, 2 H), 3.80 (s, 3 H),

4.23 (t, J ) 6.6 Hz, 2 H), 4.49 (s, 2 H), 6.45 (d, J ) 9.1 Hz, 1 H),

6.80 (dd, J ) 8.9, 2.1 Hz, 1 H), 7.01 (d, J ) 8.8 Hz, 2 H),

7.04-7.12 (m, 5 H), 7.32-7.40 (m, 6 H), 7.47-7.58 (m, 3 H),

7.67 (d, J ) 1.9 Hz, 1 H), 7.88 (d, J ) 9.1 Hz, 2 H), 8.13 (d, J )

8.8 Hz, 2 H).

Methyl 4-{2-[5-Chloro-2-(2-{[(4-cyanobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (90). 4-(Bro-

momethyl)benzonitrile (9.80 g, 50 mmol) was reacted with sodium

sulﬁte as in the general sulfonyl chloride synthesis A to generate

(4-cyanophenyl)methanesulfonyl chloride 71. The crude sulfonyl

chloride was reacted with methyl 4-(2-(2-(2-aminoethyl)-1-ben-

zhydryl-5-chloro-1H-indol-3-yl)ethoxy)benzoate amine 79⁴⁴(0.085

g, 0.15 mmol) according to the Schotten-Baumann procedure to

afford sulfonamide 90 as a gum. ¹H NMR (300 Hz, CDCl₃) δ

2.82-2.92 (m, 2 H), 3.10 (t, J ) 6.9 Hz, 2 H), 3.19 (t, J ) 6.4 Hz,

2 H), 3.88 (s, 3 H), 4.00-4.05 (m, 2 H), 4.22 (t, J ) 6.2 Hz, 2 H),

4.30 (t, J ) 6.3 Hz, 1 H), 6.52 (d, J ) 8.9 Hz, 1 H), 6.75-6.95

(m, 4 H), 7.05-7.10 (m, 4 H), 7.20-7.35 (m, 8 H), 7.55-7.65

(m, 3 H), 7.94 (d, J ) 8.9 Hz, 2 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(4-nitrobenzyl)sulfo-

nyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (85). Ester

84 (150 mg, 0.2 mmol) was hydrolyzed according to the general

1

procedure to afford the title acid (143 mg, 97% yield). H NMR

4-{2-[5-Chloro-2-(2-{[(4-cyanobenzyl)sulfonyl]amino}ethyl)-1-(di-

phenylmethyl)-1H-indol-3-yl]ethoxy}benzoic acid (91). Ester 90 was

hydrolyzed according to the general procedure to afford the title

acid (84 mg, 77% overall yield from the amine) as an off-white

(300 MHz, DMSO-d₆) δ 2.96-3.12 (m, 4 H), 3.16 (t, J ) 5.8 Hz,

2 H), 4.19 (t, J ) 6.9 Hz, 2 H), 4.49 (s, 2 H), 6.45 (d, J ) 9.1 Hz,

1 H), 6.80 (dd, J ) 8.8, 1.9 Hz, 1 H), 6.91 (d, J ) 8.8 Hz, 2 H),

7.03-7.13 (m, 5 H), 7.30-7.41 (m, 6 H), 7.50-7.63 (m, 3 H),

7.66 (d, J ) 1.9 Hz, 1 H), 7.83 (d, J ) 8.9 Hz, 2 H), 8.13 (d, J )

8.8 Hz, 2 H). HRMS calcd for [C₃₉H₃₄ClN₃O₇S + H] 724.1879;

found 724.1884.

1

solid. H NMR (400 Hz, DMSO-d₆) δ 2.95-3.15 (m, 4 H), 3.17

(t, J ) 6.5 Hz, 2 H), 4.23 (t, J ) 6.5 Hz, 2 H), 4.41 (s, 2 H), 6.46

(d, J ) 8.9 Hz, 1 H), 6.81 (dd, J ) 8.9, 2.2 Hz, 1 H), 6.97 (d, J )

8.8 Hz, 2 H), 7.05-7.15 (m, 6 H), 7.30-7.40 (m, 6 H), 7.46 (d, J

) 8.3 Hz, 2 H), 7.66 (d, J ) 2.1 Hz, 1 H), 7.74 (d, J ) 8.3 Hz, 2

H), 7.85 (d, J ) 8.8 Hz, 2 H), 12.60 (br s, 1 H). HRMS calcd

Methyl 4-{2-[5-Chloro-2-(2-{[(2-cyanobenzyl)sulfonyl]amino}

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (86).

2-(Bromomethyl)benzonitrile (3.40 g, 17.4 mmol) was reacted with

sodium sulﬁte as in the general sulfonyl chloride synthesis A to

generate (2-cyanophenyl)methanesulfonyl chloride. The crude sul-

fonyl chloride was reacted with amine 79⁴⁴(0.085 g, 0.15 mmol)

according to the Schotten-Baumann procedure to afford sulfona-

[C₄₀H₃₅ClN₃O₅S

(C₄₀H₃₄ClN₃O₅S) C, H, N.

+ H] 704.1980; found 704.1981. Anal.

Methyl

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-

2-ylmethyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (92).

This compound was prepared by stirring amine 79⁴⁴(300 mg, 0.56

mmol), 2-(pyridylmethyl)sulfonyl chloride·TFA (230 mg, 0.68

mmol), and DIEA (0.2 mL, 1.1 mmol) in CH₂Cl₂(6 mL) for 2 h.

The mixture was then subjected to an aqueous workup and puriﬁed

by ﬂash chromatography (50% EtOAc-hexanes) to afford the

1

mide 86 as a gum. H NMR (300 Hz, CDCl₃) δ 2.95–3.15 (m, 4

H), 3.18 (t, J ) 6.5 Hz, 2 H), 3.88 (s, 3 H), 4.22 (t, J ) 6.5 Hz, 2

H), 4.34 (s, 2 H), 6.49 (d, J ) 8.9 Hz, 1 H), 6.75-6.95 (m, 4 H),

7.05-7.10 (m, 4 H), 7.25-7.35 (m, 6 H), 7.35-7.45 (m, 1 H),

7.45-7.55 (m, 3 H), 7.61 (d, J ) 7.6 Hz, 1 H), 7.95 (d, J ) 8.9

Hz, 2 H).

1

sulfonamide 92 (163 mg, 42% yield) as a white foam. H NMR

(300 MHz, CDCl₃) δ 3.14 (s, 4 H), 3.23 (t, J ) 6.6 Hz, 2 H), 3.88

(s, 3 H), 4.18-4.32 (m, 4 H), 4.81 (s, 1 H), 6.49 (d, J ) 8.8 Hz,

1 H), 6.76-6.91 (m, 3 H), 6.95 (s, 1 H), 7.02-7.12 (m, 4 H), 7.18

(dd, J ) 7.1, 5.2 Hz, 1 H), 7.21-7.40 (m, 7 H), 7.56 (d, J ) 1.9

Hz, 1 H), 7.63 (dt, J ) 7.7, 1.7 Hz, 1 H), 7.94 (d, J ) 8.8 Hz, 2

H), 8.26 (d, J ) 4.1 Hz, 1 H).

4-{2-[1-Benzhydryl-5-chloro-2-(2-{[(2-cyanobenzyl)sulfonyl]-

amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (87). Ester 86

was hydrolyzed according to the general procedure to afford 87

1

(80 mg, 72% overall yield from the amine). H NMR (400 Hz,

DMSO-d₆) δ 2.95–3.15 (m, 4 H), 3.17 (t, J ) 6.5 Hz, 2 H), 4.23

(t, J ) 6.5 Hz, 2 H), 4.46 (s, 2 H), 6.47 (d, J ) 8.9 Hz, 1 H), 6.81

(dd, J ) 8.9, 2.1 Hz, 1 H), 6.98 (d, J ) 8.8 Hz, 2 H), 7.05-7.10

(m, 6 H), 7.30-7.40 (m, 6 H), 7.50-7.58 (m, 2 H), 7.60-7.70

(m, 3 H), 7.80-7.90 (m, 2 H), 12.60 (br s, 1 H). HRMS calcd

[C₄₀H₃₅ClN₃O₅S + H] 704.198 04; found 704.198 39.

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-2-ylmethyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic acid (93). Ester 92

(163 mg, 0.23 mmol) was hydrolyzed according to the general

1

procedure to afford 93 (90 mg, 56% yield) as a white foam. H

NMR (300 MHz, DMSO-d₆) δ 2.92-3.25 (m, 6 H), 4.22 (t, J )

3406 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

6.7 Hz, 2 H), 4.43 (s, 2 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.80 (dd, J

) 8.9, 2.1 Hz, 1 H), 6.99 (d, J ) 8.8 Hz, 2 H), 7.04-7.19 (m, 5

H), 7.26-7.53 (m, 9 H), 7.66 (d, J ) 1.9 Hz, 1 H), 7.73 (dt, J )

7.7, 1.9 Hz, 1 H), 7.85 (d, J ) 8.8 Hz, 2 H), 8.44 (d, J ) 4.9 Hz,

1 H). HRMS calcd [C₃₈H₃₄Cl₁N₃O₅S₁- H] 678.183 49; found

678.183 12.

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-3-yl-

methyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (94).

This compound was prepared by reacting amine 79⁴⁴(150 mg, 0.28

mmol) with 3-(pyridylmethyl)sulfonyl chloride ·TFA (115 mg, 0.34

mmol) using the DIEA procedure described for 92. Aqueous workup

and ﬂash chromatography (2% MeOH-CH₂Cl₂) afforded the

sulfonamide 94 (100 mg, 52% yield) as a yellow oil. ¹H NMR

(300 MHz, CDCl₃) δ 2.92 (q, J ) 7.1 Hz, 2 H), 3.03-3.15 (m, 2

H), 3.19 (t, J ) 6.6 Hz, 2 H), 3.88 (s, 3 H), 4.01 (s, 2 H), 4.22 (t,

J ) 6.6 Hz, 2 H), 4.54 (t, J ) 6.0 Hz, 1 H), 6.53 (d, J ) 8.8 Hz,

1 H), 6.74-6.88 (m, 3 H), 6.91 (s, 1 H), 7.00-7.14 (m, 4 H), 7.22

(dd, J ) 8.1, 5.1 Hz, 1 H), 7.28-7.39 (m, 6 H), 7.54 (d, J ) 1.9

Hz, 1 H), 7.60 (d, J ) 8.0 Hz, 1 H), 7.95 (d, J ) 8.8 Hz, 2 H),

8.39 (s, 1 H), 8.52 (d, J ) 4.4 Hz, 1 H).

procedure to afford the title acid (46 mg, 73% yield) as an off-

white foam. H NMR (300 MHz, DMSO-d₆) δ 0.65-1.35 (m, 6

1

H), 1.46-1.81 (m, 5 H), 2.71 (d, J ) 5.5 Hz, 2 H), 3.06 (s, 4 H),

3.20 (t, J ) 5.4 Hz, 2 H), 4.11-4.37 (m, 2 H), 6.48 (d, J ) 8.8

Hz, 1 H), 6.81 (dd, J ) 8.8, 2.2 Hz, 1 H), 6.98 (d, J ) 9.1 Hz, 2

H), 7.10 (dd, J ) 7.4, 1.9 Hz, 5 H), 7.25-7.52 (m, 7 H), 7.67 (d,

J ) 1.9 Hz, 1 H), 7.84 (d, J ) 8.8 Hz, 2 H). HRMS calcd

[C₃₉H₄₁Cl₁N₂O₅S₁- H] 683.235 19; found 683.23474.

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-naphthyl-

methyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (100).

2-(Bromomethyl)naphthalene (1.6 g, 7.4 mmol) was reacted with

sodium sulﬁte as in the general sulfonyl chloride synthesis A to

generate 2-naphthylmethanesulfonyl chloride 72. The crude sulfonyl

chloride was reacted with amine 79⁴⁴(0.17 g, 0.32 mmol) according

to the Schotten-Baumann procedure. Flash chromatography

(10-40% EtOAc-hexanes) afforded the sulfonamide 100 (140 mg,

58% yield) as a white foam. ¹H NMR (300 MHz, CDCl₃) δ

2.80-2.98 (m, 2 H), 2.99-3.24 (m, 4 H), 3.88 (s, 3 H), 4.05-4.18

(m, 3 H), 4.20 (s, 2 H), 6.51 (d, J ) 8.8 Hz, 1 H), 6.70-6.85 (m,

3 H), 6.88 (s, 1 H), 6.98-7.12 (m, 4 H), 7.19-7.36 (m, 7 H),

7.43-7.56 (m, 3 H), 7.63 (s, 1 H), 7.65-7.75 (m, 2 H), 7.76-7.85

(m, 1 H), 7.91 (d, J ) 9.1 Hz, 2 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-naphthylmethyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (101). Ester

100 (137 mg, 0.18 mmol) was hydrolyzed according to the general

procedure to afford 101 (100 mg, 75% yield) as a white foam. ¹H

NMR (300 MHz, DMSO-d₆) δ 2.87-3.25 (m, 6 H), 4.19 (t, J )

6.7 Hz, 2 H), 4.44 (s, 2 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.80 (dd, J

) 8.8, 2.2 Hz, 1 H), 6.98 (d, J ) 8.8 Hz, 2 H), 7.03-7.20 (m, 5

H), 7.28-7.45 (m, 8 H), 7.46-7.56 (m, 2 H), 7.66 (d, J ) 1.9 Hz,

1 H), 7.73-7.97 (m, 6 H). HRMS calcd for [C₄₃H₃₇ClN₂O₅S +

H] 729.2185; found 729.2189.

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-3-ylmethyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (95). Ester

94 (100 mg, 0.14 mmol) was hydrolyzed according to the general

1

procedure to afford 95 (92 mg, 94% yield) as a yellow foam. H

NMR (300 MHz, DMSO-d₆) δ 2.85-3.25 (m, 6 H), 4.22 (t, J )

6.5 Hz, 2 H), 4.35 (s, 2 H), 6.46 (d, J ) 8.8 Hz, 1 H), 6.82 (d, J

) 1.9 Hz, 1 H), 6.99 (d, J ) 8.8 Hz, 2 H), 7.09 (appar dd, J ) 5.2,

2.2 Hz, 5 H), 7.25-7.44 (m, 7 H), 7.50 (t, J ) 5.5 Hz, 1 H),

7.61-7.75 (m, 2 H), 7.86 (d, J ) 9.1 Hz, 2 H), 8.42-8.56 (m, 2

H). HRMS calcd [C₃₈H₃₄Cl₁N₃O₅S₁- H] 678.183 49; found

678.182 77.

Methyl

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-

4-ylmethyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (96).

This compound was prepared using methyl 4-{2-[2-(2-aminoethyl)-

1-benzhydryl-5-chloro-1H-indol-3-yl]ethoxy}benzoate 79⁴⁴(150

mg, 0.28 mmol) and 4-(pyridylmethyl)sulfonyl chloride·TFA (115

mg, 0.34 mmol) using the DIEA procedure described for 92.

Aqueous workup and puriﬁcation by ﬂash chromatography (2%

MeOH-CH₂Cl₂) afforded the sulfonamide 96 (110 mg, 57% yield)

Methyl 4-{2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (102). To

amine 79⁴⁴(215 mg, 0.4 mmol) was added (2-chlorophenyl-

)methanesulfonylchloride(0.45g,2.0mmol)usingtheSchotten-Baumann

general procedure to generate the sulfonamide 102 (250 mg, 86%

yield) as a white foam. ¹H NMR (300 MHz, CDCl₃) δ 2.88-2.97

(m, 2 H), 3.01-3.11 (m, 2 H), 3.18 (t, J ) 6.5 Hz, 2 H), 3.88 (s,

3 H), 4.19 (t, J ) 6.5 Hz, 1 H), 4.26 (t, J ) 6.0 Hz, 1 H), 4.34 (s,

2 H), 6.50 (d, J ) 8.8 Hz, 1 H), 6.78-6.93 (m, 4 H), 7.02-7.12

(m, 4 H), 7.16 – 7.38 (m, 9 H), 7.41 (d, J ) 7.4 Hz, 1 H), 7.53 (d,

J ) 1.6 Hz, 1 H), 7.95 (d, J ) 8.0 Hz, 2 H).

4-{2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}ethyl)-1-

(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (103). Ester

102 (250 mg, 0.34 mmol) was hydrolyzed according to the general

procedure to afford acid 103 (237 mg, 90% yield) as a yellow foam.

¹H NMR (300 MHz, CDCl₃) δ 2.95 (d, J ) 14.0 Hz, 2 H),

3.02-3.13 (m, 2 H), 3.19 (t, J ) 6.5 Hz, 2 H), 4.21 (t, J ) 6.5 Hz,

2 H), 4.34 (s, 2 H), 4.48 (t, J ) 5.9 Hz, 1 H), 6.50 (d, J ) 8.8 Hz,

1 H), 6.78-6.94 (m, 4 H), 7.03-7.12 (m, 4 H), 7.14-7.25 (m, 2

H), 7.28-7.35 (m, 7 H), 7.41 (dd, J ) 7.4, 1.9 Hz, 1 H), 7.53 (d,

J ) 2.2 Hz, 1 H), 8.00 (d, J ) 8.8 Hz, 2 H). HRMS calcd for

[C₃₉H₃₄Cl₂N₂O₅S + H] 713.1638; found 713.1644.

1

as a yellow oil. H NMR (300 MHz, CDCl₃) δ 2.91 (q, J ) 7.2

Hz, 2 H), 3.04-3.38 (m, 4 H), 3.88 (s, 3 H), 3.98 (s, 2 H), 4.23 (t,

J ) 6.5 Hz, 2 H), 4.63 (t, J ) 5.9 Hz, 1 H), 6.54 (d, J ) 9.1 Hz,

1 H), 6.84 (d, J ) 9.1 Hz, 3 H), 6.91 (s, 1 H), 7.02-7.19 (m, 6 H),

7.28-7.43 (m, 6 H), 7.54 (d, J ) 1.6 Hz, 1 H), 7.95 (d, J ) 9.1

Hz, 2 H), 8.46 (d, J ) 5.8 Hz, 2 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(pyridin-4-ylmethyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (97). Ester

96 (110 mg, 0.16 mmol) was hydrolyzed according to the general

procedure to afford acid 97 (111 mg, 94% yield) as a white foam.

¹H NMR (300 MHz, DMSO-d₆) δ 2.93-3.24 (m, 6 H), 4.22 (t, J

) 6.6 Hz, 2 H), 4.35 (s, 2 H), 6.47 (d, J ) 8.8 Hz, 1 H), 6.81 (dd,

J ) 8.4, 1.8 Hz, 1 H), 6.98 (d, J ) 9.1 Hz, 2 H), 7.04-7.19 (m,

5 H), 7.27 (d, J ) 5.8 Hz, 2 H), 7.32-7.44 (m, 6 H), 7.53 (t, J )

5.1 Hz, 1 H), 7.67 (d, J ) 1.9 Hz, 1 H), 7.86 (d, J ) 8.5 Hz, 2 H),

8.48 (d, J ) 5.8 Hz, 2 H). HRMS calcd [C₃₈H₃₄Cl₁N₃O₅S₁- H]

678.183 49; found 678.182 49.

Methyl 4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-methylben-

zyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoate (104). 2-M-

ethylphenylmethanesulfonyl chloride was reacted with amine 79⁴⁴

(0.116 g, 0.17 mmol) according to the Schotten-Baumann proce-

dure. Flash chromatography (gradient elution EtOAc-hexanes)

Methyl 4-{2-[5-Chloro-2-(2-{[(cyclohexylmethyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (98).

Cyclohexylmethanesulfonyl chloride was reacted with 79⁴⁴(0.25

g, 0.46 mmol) according to the Schotten-Baumann procedure and

afforded sulfonamide 98 (64 mg, 20% yield) as a pale-yellow foam

after puriﬁcation by ﬂash chromatography (gradient elution 20-50%

1

afforded the sulfonamide 104 (0.049 g, 35% yield) as a solid. H

NMR (300 MHz, CDCl₃) δ ppm 2.12 (s, 3 H), 2.63-2.73 (m, 2

H), 2.84-2.94 (m, 2 H), 2.97-3.05 (m, 2 H), 3.71 (s, 3 H), 3.96

(s, 2 H), 3.97-4.06 (m, 2 H), 6.34 (d, J ) 9.1 Hz, 1 H), 6.61-6.69

(m, 3 H), 6.72 (s, 1 H), 6.85-6.92 (m, 6 H), 6.93-7.05 (m, 2 H),

7.10-7.19 (m, 6 H), 7.36 (d, J ) 1.9 Hz, 1 H), 7.78 (d, J ) 8.8

Hz, 2 H).

4-{2-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-methylbenzyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (105). Ester

104 (0.046 g, 0.07 mmol) was hydrolyzed according to the general

procedure to afford acid 105 (0.031 g, 69% yield) as a beige solid.

¹H NMR (300 MHz, CDCl₃) δ ppm 2.13 (s, 3 H), 2.62-2.74 (m,

1

EtOAc-hexanes). H NMR (300 MHz, CDCl₃) δ 0.60-1.43 (m,

7 H), 1.58-1.89 (m, 4 H), 2.61 (d, J ) 5.8 Hz, 2 H), 2.90-3.09

(m, 2 H), 3.10-3.35 (m, 4 H), 3.88 (s, 3 H), 4.14 (t, J ) 6.9 Hz,

1 H), 4.25 (t, J ) 6.5 Hz, 2 H), 6.54 (d, J ) 8.8 Hz, 1 H), 6.75-6.91

(m, 3 H), 6.95 (s, 1 H), 7.09 (dd, J ) 3.4, 2.6 Hz, 4 H), 7.28-7.48

(m, 6 H), 7.56 (d, J ) 2.2 Hz, 1 H), 7.96 (d, J ) 8.5 Hz, 2 H).

4-{2-[5-Chloro-2-(2-{[(cyclohexylmethyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (99). Ester

98 (64 mg, 0.091 mmol) was hydrolyzed according to the general

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3407

2 H), 2.83-2.94 (m, 2 H), 2.95-3.06 (m, 2 H), 3.96 (s, 2 H), 4.02

(t, J ) 6.9 Hz, 2 H), 6.34 (d, J ) 8.5 Hz, 1 H), 6.59-6.70 (m, 3

H), 6.72 (s, 1 H), 6.84-6.93 (m, 6 H), 7.11-7.19 (m, 8 H), 7.35

(s, 1 H), 7.82 (d, J ) 8.2 Hz, 2 H). HRMS calcd for

[C₄₀₁H₃₇ClN₂O₅S - H] 691.203 89; found 691.203 50.

7.26-7.28 (m, 3 H), 7.29-7.31 (m, 2 H), 7.31-7.36 (m, 6 H),

7.43 (d, J ) 1.9 Hz, 1 H), 7.96 (d, J ) 8.2 Hz, 2 H)

4-{3-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid (111). Ester

110 (0.45 g, 0.61 mmol) was hydrolyzed according to the general

procedure to afford 111 (0.39 g, 86% yield), mp 172 °C. ¹H NMR

(300 MHz, CDCl₃) δ 1.92-2.04 (m, 2 H), 2.70-2.85 (m, 6 H),

2.93-3.02 (m, 2 H), 3.94 (s, 2 H), 6.52 (d, J ) 8.8 Hz, 1 H), 6.82

(dd, J ) 8.8, 2.2 Hz, 1 H), 6.87 (s, 1 H), 7.00 (dd, J ) 8.2, 1.9 Hz,

1 H), 7.05-7.11 (m, 4 H), 7.26-7.28 (m, 2 H), 7.30 (d, J ) 2.7

Hz, 2 H), 7.31-7.37 (m, 6 H), 7.42 (d, J ) 1.9 Hz, 1 H), 8.01 (d,

J ) 8.2 Hz, 2 H). Anal. (C₄₀H₃₅Cl₃N₂O₄S) C, H, N. HRMS calc

for [C₄₀H₃₅Cl₃N₂O₄S + H] 745.1456; found 745.1458.

2,6-Dimethylphenylmethanesulfonyl Chloride (77). This com-

pound was synthesized using sulfonyl chloride general procedure

C. 2-Chloromethyl-1,3-dimethylbenzene (10 g, 64.7 mmol) was

treated as in the general procedure to yield the desired sulfonate

sodium salt (11.92 g, 83%). This material was treated with HCl

(90% yield of 74) and chlorinated (92% yield of 77) as described

1

in the general procedure to yield sulfonyl chloride 77. H NMR

(300 MHz, CDCl₃) δ ppm 2.50 (s, 6 H), 5.17 (s, 2 H), 7.25–7.04

(m, 3 H).

Methyl 4-({2-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}-

Methyl 4-{2-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (106).

To amine 79⁴⁴(114 mg, 0.212 mmol) was added 2,6-dimethylphe-

nylmethanesulfonyl chloride 77 using the Schotten-Baumann

general procedure. Flash chromatography afforded the sulfonamide

106 (0.069 g, 45% yield). ¹H NMR (300 MHz, CDCl₃) δ ppm

2.11 (s, 6 H), 2.61-2.72 (m, 2 H), 2.82-2.92 (m, 2 H), 2.96-3.06

(m, 2 H), 3.71 (s, 3 H), 3.98-4.07 (m, 3 H), 4.13 (s, 2 H), 6.34 (d,

J ) 8.8 Hz, 1 H), 6.61-6.73 (m, 4 H), 6.78 (s, 1 H), 6.81 (s, 1 H),

6.85-6.95 (m, 5 H), 7.10-7.18 (m, 6 H), 7.36 (d, J ) 1.9 Hz, 2

H), 7.79 (d, J ) 8.8 Hz, 2 H).

sulfonyl)benzoate (112). This compound was prepared from amine

33 (0.15 g, 0.23 mmol) and (3,4-dichlorophenyl)methanesulfonyl

chloride (0.14 g, 0.54 mmol) according to the Schotten-Baumann

procedure and puriﬁed using ﬂash chromatography (EtOAc-hexanes)

to afford sulfonamide 112 (0.18 g, 87% yield) as a white solid. ¹H

NMR (400 MHz, acetone-d₆) δ 3.10-3.30 (m, 6 H), 3.60-3.67

(m, 2 H), 3.96 (s, 3 H), 4.33 (s, 2 H), 6.52 (d, J ) 8.8 Hz, 1 H),

6.77 (dd, J ) 8.8, 2.0 Hz, 1 H), 7.11-7.18 (m, 5 H), 7.27 (d, J )

2.3 Hz, 1 H), 7.33 (dd, J ) 8.2, 1.9 Hz, 1 H), 7.35-7.40 (m, 6 H),

7.52 (d, J ) 8.3 Hz, 1 H), 7.59 (d, J ) 2.0 Hz, 1 H), 8.12-8.17

(m, 2 H), 8.22-8.28 (m, 2 H).

4-({2-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoic Acid (113).

Ester 112 (0.15 g, 0.19 mmol) was hydrolyzed according to the

general procedure to afford 113 (0.14 g, 93% yield) as a pale-yellow

solid; mp 94.8, 129.5 °C. ¹H NMR (400 MHz, CDCl₃) δ 2.85-2.97

(m, 2H), 2.98-3.09 (m, 2H), 3.16-3.29 (m, J ) 2.8 Hz, 2H),

3.37-3.50 (m, 2H), 4.01 (s, 2H), 4.39 (t, J ) 6.2 Hz, 1H), 6.49 (d,

J ) 8.0 Hz, 1H), 6.71-6.82 (m, 2H), 6.82-6.86 (m, 1H),

7.02-7.12 (m, 6H), 7.23 (s, 1H), 7.28-7.41 (m, 6H), 8.06 (d, J )

8.3 Hz, 2H), 8.26 (d, J ) 8.31 Hz, 2H). HRMS: calcd for

[C₃₉H₃₃Cl₃N₂O₆S₂– H] 793.077 28; found 793.076 29.

4-{2-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (107). Ester

106 (0.064 g, 0.089 mmol) was hydrolyzed according to the general

1

procedure to afford the acid 107 (0.056 g, 88% yield). H NMR

(300 MHz, DMSO-d₆) δ ppm 2.10 (s, 6 H), 2.87 (br s, 4 H),

2.94-3.02 (m, 2 H), 3.96-4.04 (m, 2 H), 4.13-4.19 (m, 2 H),

6.28 (d, J ) 8.8 Hz, 2 H), 6.62 (dd, J ) 8.7, 2.3 Hz, 2 H), 6.71 (d,

J ) 8.8 Hz, 2 H), 6.78 (s, 1 H), 6.80 (s, 1 H), 6.84-6.93 (m, 5 H),

7.12-7.22 (m, 5 H), 7.40-7.46 (m, 1 H), 7.47 (d, J ) 1.6 Hz, 1

H), 7.64 (d, J ) 8.8 Hz, 2 H). HRMS calcd for [C₄₁H₃₉Cl₁N₂O₅S₁

+ H] 707.2341; found 707.234 54.

Methyl 4-{2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoate (108).

2-(Bromomethyl)-1,3-diﬂuorobenzene (20 g, 96.6 mmol) was

reacted with sodium sulﬁte as in the general sulfonyl chloride

synthesis C to generate (2,6-diﬂuorophenyl)methanesulfonyl chlo-

ride 78. The crude sulfonyl chloride was reacted with amine 79⁴⁴

(2.0 g, 3.71 mmol) according to the Schotten-Baumann procedure.

Flash chromatography (gradient elution 10-30% EtOAc-hexanes)

afforded the sulfonamide 108 (2.65 g, 98% yield) as a white foam.

¹H NMR (300 MHz, DMSO-d₆) δ 2.96-3.24 (m, 6 H), 3.80 (s, 3

H), 4.24 (t, J ) 6.5 Hz, 2 H), 4.32 (s, 2 H), 6.46 (d, J ) 8.8 Hz,

1 H), 6.80 (dd, J ) 8.9, 2.1 Hz, 1 H), 7.01 (d, J ) 9.1 Hz, 2 H),

7.05-7.16 (m, 7 H), 7.29-7.52 (m, 7 H), 7.67 (d, J ) 2.2 Hz, 1

H), 7.73 (t, J ) 5.2 Hz, 1 H), 7.88 (d, J ) 9.1 Hz, 2 H).

4-{2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethoxy}benzoic Acid (109). Ester

108 (2.5 g, 3.43 mmol) was hydrolyzed according to the general

procedure to afford acid 109 (2.11 mg, 86% yield) as a white foam.

¹H NMR (300 MHz, DMSO-d₆) δ 2.97-3.26 (m, 6 H), 4.23 (t, J

) 6.6 Hz, 2 H), 4.32 (s, 2 H), 6.46 (d, J ) 8.8 Hz, 1 H), 6.76-6.84

(m, 1 H), 6.99 (d, J ) 8.8 Hz, 2 H), 7.04-7.17 (m, 7 H), 7.30-7.52

(m, 7 H), 7.67 (d, J ) 1.4 Hz, 1 H), 7.75 (t, J ) 5.5 Hz, 1 H), 7.86

(d, J ) 8.8 Hz, 2 H). HRMS calcd for [C₃₉H₃₃ClF₂N₂O₅S - H]

713.169 40; found 713.169 06.

Methyl 4-{3-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoate (110).

This compound was prepared from amine 22 (0.43 g, 0.80 mmol)

and (3,4-dichlorophenyl)methanesulfonyl chloride (0.22 g, 0.83

mmol) according to the Schotten-Baumann procedure and puriﬁed

using ﬂash chromatography (gradient elution with 2:1 EtOAc in

hexanes, then 10% MeOH CH₂Cl₂) to afford the sulfonamide 110

(0.47 g, 78% yield). ¹H NMR (300 MHz, CDCl₃) δ 1.87-2.04

(m, 2 H), 2.69-2.83 (m, 6 H), 2.92-3.00 (m, 2 H), 3.90 (s, 3 H),

3.93 (s, 2 H), 4.03 (t, J ) 6.2 Hz, 1 H), 6.52 (dd, J ) 8.8 Hz, 1 H),

7.00 (dd, J ) 8.1, 2.1 Hz, 1 H), 7.05-7.11 (m, 4 H), 7.25 (s, 1 H),

Methyl 4-{3-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoate(114).1-(Bro-

momethyl)-2-chlorobenzene (5.0 g, 31.0 mmol) was reacted with

PCl₅(15.0 g, 73 mmol over two additions) to generate (2-

chlorophenyl)methanesulfonyl chloride. The crude sulfonyl chloride

was dissolved in CH₂Cl₂, and the mixture was cooled to 0 °C. Then

amine 22 (6.2 g, 11.5 mmol) was added in one portion, followed

by DIEA (4.0 mL, 23 mmol). The mixture was warmed to room

temperature over 4 h. An aqueous workup was performed and ﬂash

chromatography (30% EtOAc-hexanes) afforded the sulfonamide

114 (7.89 g, 94% yield) as a white solid. ¹H NMR (300 MHz,

CDCl₃) δ 1.83-1.98 (m, 2 H), 2.63-2.74 (m, 4 H), 2.74-2.84

(m, 2 H), 2.83-2.95 (m, 2 H), 3.87 (s, 3 H), 4.29 (s, 2 H), 6.45 (d,

J ) 9.1 Hz, 1 H), 6.76 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.82 (s, 1 H),

7.02 (dd, J ) 5.8, 3.6 Hz, 4 H), 7.18-7.22 (m, 2 H), 7.25-7.32

(m, 8 H), 7.34-7.41 (m, 2 H), 7.92 (d, J ) 8.2 Hz, 2 H).

4-{3-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}ethyl)-1-

(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid (115). Ester

114 (7.89 g, 10.9 mmol) was hydrolyzed according to the general

procedure to afford the acid 115 (6.4 g, 83% yield) as a pale-yellow

1

solid. H NMR (300 MHz, CDCl₃) δ 1.84-1.98 (m, 2 H), 2.70

(m, 4 H), 2.76-2.86 (m, 2 H), 2.86-2.98 (m, J ) 7.4 Hz, 2 H),

4.30 (s, 2 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.76 (dd, J ) 8.8, 1.9 Hz,

1 H), 6.82 (s, 1 H), 7.00-7.07 (m, 4 H), 7.11-7.21 (m, 2 H),

7.22-7.25 (m, 2 H), 7.25-7.32 (m, 7 H), 7.33-7.39 (m, 2 H),

7.98 (d, J ) 8.0 Hz, 2 H). HRMS calcd for [C₄₀H₃₆Cl₂N₂O₄S -

H] 709.170 00; found 709.169 61.

Methyl 4-({2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoate (116).

To amine 33 (0.153 mg, 0.26 mmol) was added (2-chlorophenyl-

)methanesulfonyl chloride (0.200 g, 0.89 mmol) (see prep in 114),

using the Schotten-Baumann general procedure to generate the

sulfonamide 116 (0.08 g, 40% yield) after puriﬁcation by preparative

TLC (3% MeOH in CH₂Cl₂).

3408 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

4-({2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}ethyl)-1-

(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoic Acid (117).

Ester 116 (0.08 g, 0.103 mmol) was hydrolyzed according to the

general procedure to afford the acid 117 (0.063 g, 80% yield) as

an orange solid, mp 133 °C. ¹H NMR (400 MHz, CDCl₃) δ

2.89-3.01 (m, 4 H), 3.12-3.21 (m, 2 H), 3.37-3.45 (m, 2 H),

4.36 (s, 2 H), 4.52 (t, J ) 5.8 Hz, 1 H), 6.45 (d, J ) 8.8 Hz, 1 H),

6.77 (dd, J ) 9.1, 2.1 Hz, 1 H), 6.81 (s, 1 H), 7.01-7.07 (m, 4 H),

7.19 (d, J ) 2.01 Hz, 1 H), 7.21-7.24 (m, 1 H), 7.27-7.32 (m, 7

H), 7.33-7.37 (m, 1 H), 7.39-7.45 (m, 1 H), 8.05 (d, J ) 7.9 Hz,

2 H), 8.26 (d, J ) 7.93 Hz, 2 H). HRMS calcd for [C₃₉H₃₄Cl₂N₂O₆S₂

+ H] 761.130 81; found 761.131 46.

Methyl 4-{3-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-methylben-

zyl)sulfonyl]amino}ethyl)-1H-indol-3-yl]propyl}benzoate (118). This

compound was prepared using amine 22 (0.540 g, 10.0 mmol) and

[(2-methylphenyl)methane]sulfonyl chloride (15 mmol) using the

aboveDIEAprocedure.Flashchromatography(5–20%EtOAc-hexanes)

afforded the sulfonamide 118 (6.17 g, 88% yield) as a yellow foam.

¹H NMR (400 MHz, CDCl₃) δ 1.86-2.00 (m, 2 H), 2.30 (s, 3 H),

2.62-2.83 (m, 6 H), 2.84-3.02 (m, 2 H), 3.89 (s, 3 H), 4.06-4.18

(m, 3 H), 6.49 (d, J ) 8.8 Hz, 1 H), 6.75-6.83 (m, J ) 8.8, 2.0

Hz, 1 H), 6.84 (s, 1 H), 7.00-7.09 (m, 6 H), 7.09-7.14 (m, 1 H),

7.15-7.21 (m, 1 H), 7.22-7.28 (m, 2 H), 7.28-7.35 (m, 6 H),

7.40 (d, J ) 2.0 Hz, 1 H), 7.95 (d, J ) 8.1 Hz, 2 H).

4-{3-[5-Chloro-1-(diphenylmethyl)-2-(2-{[(2-methylbenzyl)sul-

fonyl]amino}ethyl)-1H-indol-3-yl]propyl}benzoic Acid (119). Ester

118 (6.0 g, 8.5 mmol) was hydrolyzed according to the general

procedure to afford acid 119 (5.03 g, 86% yield) as a yellow foam.

¹H NMR (400 MHz, DMSO-d₆) δ 1.80-1.95 (m, 2 H), 2.28 (s, 3

H), 2.71 (t, J ) 7.6 Hz, 4 H), 2.92 (br s, 4 H), 4.27 (s, 2 H), 6.44

(d, J ) 8.8 Hz, 1 H), 6.77 (dd, J ) 8.8, 2.3 Hz, 1 H), 6.99-7.12

(m, 6 H), 7.12-7.25 (m, 3 H), 7.28-7.44 (m, 9 H), 7.46 (d, J )

2.0 Hz, 1 H), 7.86 (d, J ) 8.3 Hz, 2 H), 12.76 (br s, 1 H). HRMS

calcd for [C₄₁H₃₉ClN₂O₄S + H] 691.239 18; found 691.239 46.

Anal. (C₄₁H₃₉ClN₂O₄S) C, H, N.

(m, 7 H), 7.19 (d, J ) 2.0 Hz, 1 H), 7.27-7.34 (m, 6 H), 8.03 (d,

J ) 8.6 Hz, 2 H), 8.21 (d, J ) 8.6 Hz, 2 H).

4-({2-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoic Acid (123).

Ester 122 (0.56 g, 0.73 mmol) was hydrolyzed according to the

general procedure to afford the acid 123 (0.55 g, 99% yield) as a

1

white solid, mp 144.1 °C. H NMR (400 MHz, CDCl₃) δ 2.33 (s,

6 H), 2.86-2.91 (m, 2 H), 2.92-3.00 (m, 2 H), 3.14-3.22 (m, 2

H), 3.39-3.47 (m, 2 H), 4.32-4.36 (m, 2 H), 4.61 (t, J ) 6.2 Hz,

1 H), 6.44 (d, J ) 8.8 Hz, 1 H), 6.77 (dd, J ) 8.8, 2.1 Hz, 1 H),

6.80 (s, 1 H), 6.96-7.11 (m, 7 H), 7.18 (d, J ) 2.01 Hz, 1 H),

7.27-7.35 (m, 6 H), 8.05 (d, J ) 8.3 Hz, 2 H), 8.23 (d, J ) 8.3

Hz, 2 H). HRMS calcd for [C₄₁H₃₉ClN₂O₆S₂– H] 753.186 53 found

753.185 97.

Methyl 4-{3-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoate (124).

To amine 22 (400 mg, 7.4 mmol) was added (2,6-diﬂuorophenyl-

)methanesulfonyl chloride 78 using the Schotten-Baumann general

procedure and ﬂash chromatography (20% EtOAc-hexanes) to

afford sulfonamide 124 (180 mg, 33% yield). ¹H NMR (300 MHz,

CDCl₃) δ 1.86-2.03 (m, 2 H), 2.61-2.80 (m, 4 H), 2.85-3.05

(m, 4 H), 3.90 (s, 3 H), 4.03-4.15 (m, 1 H), 4.22 (d, 2 H), 6.49 (d,

J ) 8.5 Hz, 1 H), 6.71-6.95 (m, 4 H), 6.98-7.15 (m, 4 H),

7.19-7.37 (m, 9 H), 7.41 (d, J ) 1.9 Hz, 1 H), 7.95 (d, J ) 8.5

Hz, 2 H).

4-{3-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid (125). Ester

124 (180 mg, 0.25 mmol) was hydrolyzed according to the general

1

procedure to afford acid 125 (46 mg, 26% yield). H NMR (300

MHz, CDCl₃) δ 1.78-2.03 (m, 2 H), 2.59-2.85 (m, 4 H),

2.84-3.08 (m, 4 H), 4.18-4.26 (m, 2 H), 4.25-4.32 (m, 1 H),

6.49 (d, J ) 8.8 Hz, 1 H), 6.66-6.94 (m, 4 H), 7.08 (s, 4 H),

7.19-7.39 (m, 9 H), 7.42 (s, 1 H), 8.00 (d, J ) 8.2 Hz, 2 H).

HRMS calcd for [C₄₀H₃₅ClF₂N₂O₄S - H] 711.190 13; found

711.189 65.

Methyl 4-{3-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]-

amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoate

(120). This compound was prepared by reacting amine 22 (4.40 g,

8.3 mmol) with (2,6-dimethylphenyl)methanesulfonyl chloride 77

(2.67 g, 12.0 mmol) using the DIEA procedure described for 92.

Aqueous workup and puriﬁcation by ﬂash chromatography (gradient

elution 5–30% EtOAc-hexanes) afforded the sulfonamide 120

(4.82 g, 81% yield) as a white foam. ¹H NMR (400 MHz, CDCl₃)

δ 1.87-2.01 (m, 2 H), 2.31 (s, 6 H), 2.65-2.82 (m, 6 H), 2.88-2.97

(m, 2 H), 3.90 (s, 3 H), 4.04 (t, J ) 6.2 Hz, 1 H), 4.28 (s, 2 H),

6.49 (d, J ) 8.8 Hz, 1 H), 6.80 (dd, J ) 8.8, 2.3 Hz, 1 H), 6.83 (s,

1 H), 6.96 (appar d, J ) 7.3 Hz, 2 H), 7.02-7.08 (m, 5 H),

7.21-7.28 (m, 3 H), 7.29-7.36 (m, 5 H), 7.40 (d, J ) 2.3 Hz, 1

H), 7.96 (d, J ) 8.3 Hz, 2 H).

Methyl 4-({2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]-

amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)-

benzoate (126). To amine 33 (0.157 g, 0.27 mmol) was added (2,6-

diﬂuorophenyl)methanesulfonyl chloride 78 (0.21 g, 0.91 mmol)

using the Schotten-Baumann general procedure and ﬂash chro-

matography (3% MeOH/CH₂Cl₂) to afford sulfonamide 126 (0.14

1

g, 67% yield). H NMR (400 MHz, CDCl₃) δ 2.98-3.08 (m, 4

H), 3.15-3.24 (m, 2 H), 3.37-3.45 (m, 2 H), 3.97 (s, 3 H), 4.26

(s, 2 H), 4.51 (t, J ) 5.8 Hz, 1 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.78

(dd, J ) 8.8, 2.0 Hz, 1 H), 6.85 (s, 1 H), 6.87-6.96 (m, 2 H), 7.05

(dd, J ) 5.7, 3.7 Hz, 4 H), 7.21 (d, J ) 2.0 Hz, 1 H), 7.27-7.35

(m, 7 H), 8.02 (d, J ) 8.6 Hz, 2 H), 8.22 (d, J ) 8.8 Hz, 2 H)

4-({2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)benzoic Acid (127).

Ester 126 (0.14 g, 0.18 mmol) was hydrolyzed according to the

general procedure to afford acid 127 (0.13 g, 96% yield) as a pale-

yellow solid, mp 124 °C. ¹H NMR (400 MHz, CDCl₃) δ 2.97-3.10

(m, 4 H), 3.14-3.24 (m, 2 H), 3.37-3.49 (m, 2 H), 4.27 (s, 2 H),

4.77 (t, J ) 5.8 Hz, 1 H), 6.45 (d, J ) 8.0 Hz, 1 H), 6.74-6.80

(m, 1 H), 6.85 (s, 1 H), 6.86-6.94 (m, 2 H), 7.06 (dd, J ) 5.7, 3.4

Hz, 4 H), 7.20 (t, J ) 2.1 Hz, 1 H), 7.27-7.34 (m, 7 H), 8.04 (d,

J ) 8.3 Hz, 2 H), 8.22 (d, J ) 8.3 Hz, 2 H). HRMS calcd for

[C₃₉H₃₃ClF₂N₂O₆S₂- H] 761.136 38; found 761.135 65.

Methyl 3-[4-({2-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]-

amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)-

phenyl]propanoate (135). This compound was prepared from amine

43 (0.130 g, 0.21 mmol) and (3,4-dichlorophenyl)methanesulfonyl

chloride (0.061 g, 0.23 mmol) according to the Schotten-Baumann

procedure and puriﬁed using ﬂash chromatography (EtOAc-hexanes)

to afford sulfonamide 135 (0.150 g, 85% yield) as a white solid.

¹H NMR (400 MHz, CDCl₃) δ 2.67 (t, J ) 7.6 Hz, 2 H), 2.88-3.01

(m, 4 H), 3.05 (t, J ) 7.6 Hz, 2 H), 3.11-3.18 (m, 2 H), 3.33-3.40

(m, 2 H), 3.66 (s, 3 H), 4.00 (s, 2 H), 6.47 (d, J ) 8.8 Hz, 1 H),

6.72 (dd, J ) 7.3, 1.8 Hz, 1 H), 6.79 (dd, J ) 8.8, 2.0 Hz, 1 H),

6.83 (d, J ) 7.3 Hz, 1 H), 6.86 (s, 1 H), 7.02-7.09 (m, 4 H),

4-{3-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid (121). Ester

120 (0.81 g, 1.1 mmol) was hydrolyzed according to the general

procedure to afford acid 121 (0.73 g, 93% yield) as a white foam,

mp 194–195 °C. ¹H NMR (400 MHz, DMSO-d₆) δ 1.81-1.95 (m,

2 H), 2.30 (s, 6 H), 2.68-2.79 (m, 4 H), 2.87-3.08 (m, 4 H), 4.34

(s, 2 H), 6.45 (d, J ) 8.8 Hz, 1 H), 6.78 (dd, J ) 8.8, 2.0 Hz, 1 H),

6.98 (appar d, J ) 7.1 Hz, 2 H), 7.03-7.14 (m, 6 H), 7.25-7.41

(m, 8 H), 7.46 (d, J ) 2.3 Hz, 1 H), 7.51 (t, J ) 5.3 Hz, 1 H), 7.85

(d, J ) 8.1 Hz, 2 H). HRMS calcd for C₄₂H₄₁ClN₂O₄S + H]

705.254 83; found 705.254 86. Anal. (C₄₂H₄₁ClN₂O₄S) C, H, N.

Methyl 4-({2-[5-Chloro-2-(2-{[(2,6-dimethylbenzyl)sulfonyl]-

amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)-

benzoate (122). This compound was prepared by reacting amine

33 (0.51 g, 0.87 mmol) with (2,6-dimethylphenyl)methanesulfonyl

chloride 77 (0.58 g, 2.63 mmol) using the Schotten-Baumann

general procedure and ﬂash chromatography (1% MeOH/CH₂Cl₂)

1

to afford the sulfonamide 122 (0.54 g, 81% yield). H NMR (400

MHz, CDCl₃) δ 2.33 (s, 6 H), 2.88 (t, J ) 6.7 Hz, 2 H), 2.95 (d,

J ) 7.1 Hz, 2 H), 3.14-3.20 (m, 2 H), 3.37-3.45 (m, 2 H), 3.97

(s, 3 H), 4.33 (s, 2 H), 4.39 (t, J ) 6.2 Hz, 1 H), 6.44 (d, J ) 8.8

Hz, 1 H), 6.77 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.81 (s, 1 H), 6.96-7.12

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3409

7.20-7.22 (m, 1 H), 7.28-7.33 (m, 5 H), 7.33-7.36 (m, 2 H),

7.40 (d, J ) 8.6 Hz, 2 H), 7.86 (d, J ) 8.3 Hz, 2 H).

(132). MsCl (0.26 mL, 3.4 mmol) and Et₃N (0.58 mL, 4.2 mmol)

were added to a solution of alcohol 131 (1.04 g, 1.65 mmol) in

CH₂Cl₂(0.02 M) at 0 °C. After 1 h the reaction mixture was warmed

to room temperature. After 1 h, aqueous workup afforded 132 (1.21

g, 98% yield) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ

1.23 (t, J ) 7.2 Hz, 3 H), 2.65 (t, J ) 7.7 Hz, 2 H), 2.83 (s, 3 H),

3.05 (t, J ) 7.7 Hz, 2 H), 3.16-3.25 (m, 4 H), 3.34-3.40 (m, 2

H), 4.03 (t, J ) 6.9 Hz, 2 H), 4.13 (q, J ) 7.1 Hz, 2 H), 6.50 (d,

J ) 8.8 Hz, 1 H), 6.81 (dd, J ) 8.8, 2.0 Hz, 1 H), 6.87 (s, 1 H),

7.02-7.09 (m, 4 H), 7.20 (d, J ) 2.0 Hz, 1 H), 7.29-7.35 (m, 6

H), 7.42 (d, J ) 8.6 Hz, 2 H), 7.90 (d, J ) 8.3 Hz, 2 H).

Ethyl 3-[4-({2-[2-(2-Azidoethyl)-5-chloro-1-(diphenylmethyl)-1H-

indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (133). A solution of

mesylate 132 (1.17 g, 1.65 mmol), sodium azide (0.54 g, 8.3 mmol),

and DMF (0.05 M) was heated to 60 °C. After 1 h the mixture was

cooled and aqueous workup provided 132 (1.04 g, 96% yield) as a

tan solid. ¹H NMR (400 MHz, CDCl₃) δ 1.23 (t, J ) 7.1 Hz, 3 H),

2.66 (t, J ) 7.7 Hz, 2 H), 2.95 (t, J ) 3.4 Hz, 2 H), 3.06 (t, J )

7.7 Hz, 2 H), 3.11-3.21 (m, 4 H), 3.33-3.40 (m, 2 H), 4.13 (q, J

) 7.2 Hz, 2 H), 6.49 (d, J ) 9.1 Hz, 1 H), 6.80 (dd, J ) 8.8, 2.01

Hz, 1 H), 6.87 (s, 1 H), 7.02-7.08 (m, 4 H), 7.13 (d, J ) 2.0 Hz,

1 H), 7.28-7.34 (m, 6 H), 7.44 (d, J ) 8.6 Hz, 2 H), 7.90 (d, J )

8.3 Hz, 2 H).

3-[4-({2-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]amino}-

ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]-

propanoic Acid (136). Ester 135 (0.120 g, 0.143 mmol) was

hydrolyzed according to the general procedure to afford 136 (0.101

1

g, 86% yield) as a white solid, mp 115–118 °C. H NMR (400

MHz, CDCl₃) δ 2.53-2.75 (m, 4H), 2.78-2.85 (m, 2H), 2.87-2.95

(m, 2H), 3.03 (t, J ) 6.6 Hz, 2H), 3.20-3.36 (m, 2 H), 3.98 (s,

2H), 6.12 (s, 1H), 6.40 (d, J ) 8.8 Hz, 1H), 6.73 (dd, J ) 7.4, 1.89

Hz, 1H), 6.76-6.85 (m, 3H), 6.94-7.08 (m, 5H), 7.28-7.37 (m,

6H), 7.38-7.44 (m, 1H), 7.46 (d, J ) 8.3 Hz, 2H), 7.89 (d, J )

8.31 Hz, 2H). Anal. (C₄₁H₃₇Cl₃N₂O₆S₂) C, H, N. HRMS calcd for

[C₄₁H₃₇Cl₃N₂O₆S₂+ H] 823.123 14; found 823.122 92.

Ethyl 3-[4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-

1H-indol-3-yl]ethyl}thio)phenyl]propanoate (128). 2-(2-{[tert-

Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-1-(diphenylmethyl)-1H-

indole

26

(7.98

g,

18.4

mmol),

ethyl

3-{4-[(2-

oxoethyl)thio]phenyl}propanoate (15.03 g, 59.6 mmol), TFA (4.25

mL, 55.2 mmol), and Et₃SiH (35 mL, 219.1 mmol) were reacted

following the general reductive alkylation procedure to yield, after

puriﬁcation via ﬂash chromatography (20% EtOAc-hexanes), 128

(7.92 g, 64% yield) as a yellow oil.

Ethyl 3-[4-({2-[2-(2-Aminoethyl)-5-chloro-1-(diphenylmethyl)-

1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (134). A suspension

of azide 133 (1.0 g, 1.53 mmol), PPh₃(0.66 g, 2.0 mmol, polymer

supported loaded at 3mmol/g), and THF (0.1 M) was stirred

overnight. H₂O (1 mL/mmol benzoate) was added, and the mixture

was stirred overnight. The solution was concentrated and puriﬁed

via ﬂash chromatography (2% MeOH in CH₂Cl₂) to afford 134

(0.63 g, 65% yield) as a tan solid. ¹H NMR (400 MHz, DMSO-d₆)

δ 1.14 (t, J ) 7.1 Hz, 3 H), 2.49-2.52 (m, 2 H), 2.55 (t, J ) 7.1

Hz, 2 H), 2.68 (t, J ) 7.4 Hz, 2 H), 2.76-2.83 (m, 2 H), 2.94-3.01

(m, 4 H), 3.52-3.60 (m, 2 H), 4.04 (q, J ) 7.1 Hz, 2 H), 6.49 (d,

J ) 8.8 Hz, 2 H), 6.75 (dd, J ) 8.8, 2.0 Hz, 1 H), 7.05-7.10 (m,

4 H), 7.12-7.17 (m, 2 H), 7.28-7.38 (m, 5 H), 7.53 (d, J ) 8.3

Hz, 2 H), 7.90 (d, J ) 8.3 Hz, 2 H).

Ethyl 3-[4-({2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]ami-

no}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phe-

nyl]propanoate (137). To amine 134 (0.15 g, 0.24 mmol) was added

(2-chlorophenyl)methanesulfonyl chloride (0.12 g, 0.53 mmol; see

114 preparation) using the Schotten-Baumann general procedure

to generate the sulfonamide 137 (0.15 g, 76% yield) after puriﬁca-

tion by preparative TLC (2% MeOH in CH₂Cl₂eluant).

3-[4-({2-[5-Chloro-2-(2-{[(2-chlorobenzyl)sulfonyl]amino}ethyl)-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]propan-

oic Acid (138). Ester 137 (0.15 g, 0.18 mmol) was hydrolyzed

according to the general procedure to acid 138 (0.12 g, 83% yield)

as a tan solid, mp 113 °C. ¹H NMR (400 MHz, CDCl₃) δ 2.55-2.65

(m, 2 H), 2.66-2.75 (m, 2 H), 2.75-2.82 (m, 2 H), 2.84-2.94

(m, 2 H), 2.98-3.06 (m, 2 H), 3.20-3.32 (m, 2 H), 4.33 (s, 2 H),

5.98-6.08 (t, J ) 5.9 Hz, 1H), 6.38 (d, J ) 9.06 Hz, 1 H), 6.76 (s,

1 H), 6.78 (d, J ) 2.01 Hz, 1 H), 6.96-7.06 (m, 4 H), 7.12-7.37

(m, 10 H), 7.38-7.41 (m, 1 H), 7.45 (d, J ) 8.3 Hz, 2 H), 7.89 (d,

J ) 8.3 Hz, 2 H). HRMS calcd for [C₄₁H₃₈Cl₂N₂O₆S₂+ H]

789.162 11; found 789.163 11.

Methyl 3-[4-({2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]-

amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)-

phenyl]propanoate (139). To amine 43 (0.085 g, 0.14 mmol) was

added (2,6-diﬂuorophenyl)methanesulfonyl chloride 78 (0.038 g,

0.17 mmol) using the Schotten-Baumann general procedure to

afford the sulfonamide 139 (0.047 g, 42% yield).

Ethyl

3-[4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-

chloro-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}thio)phenyl]pro-

panoate (129). Indole 128 (7.61 g, 11.4 mmol), NaH (0.50 g, 12.5

mmol), Ph₂CHBr (5.1 g, 20.5 mmol) were reacted using the general

N-alkylation conditions to afford, after puriﬁcation via ﬂash

chromatography (16% EtOAc-hexanes), 129 (4.03 g, 42% yield)

1

as a yellow gum. H NMR (400 MHz, CDCl₃) δ 0.99 (s, 9 H),

1.19-1.29 (m, 5 H), 2.59 (t, J ) 7.9 Hz, 2 H), 2.87-2.95 (m, 3

H), 2.98-3.07 (m, 3 H), 3.65 (t, J ) 7.4 Hz, 2 H), 4.12 (q, J ) 7.1

Hz, 2 H), 6.36 (d, J ) 8.8 Hz, 1 H), 6.69 (s, 1 H), 6.73 (dd, J )

8.8, 2.27 Hz, 1 H), 6.91 (d, J ) 7.1 Hz, 3 H), 7.12 (d, J ) 8.3 Hz,

2 H), 7.18-7.31 (m, 12 H), 7.32-7.43 (m, 4 H), 7.48-7.53 (m, 4

H).

Ethyl3-[4-({2-[2-(2-{[tert-Butyl(diphenyl)silyl]oxy}ethyl)-5-chloro-

1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]propano-

ate (130). NMO (2.23 g, 19.1 mmol) was added to a solution

containing silyl ether 129 (3.9 g, 4.7 mmol), CH₃CN (0.1 M), and

molecular sieves (1 g/mmol benzoate). After 10 min, TPAP (0.084

g, 0.24 mmol) was added and the mixture was heated to 40 °C.

After 1.5 h the mixture was cooled and the ﬁltrate was puriﬁed via

ﬂash chromatography (25% EtOAc-hexanes) to deliver 130 (3.51

g, 86% yield) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ

0.99 (s, 9 H), 1.20-1.28 (m, 5 H), 2.64 (t, J ) 7.7 Hz, 2 H),

2.96-3.06 (m, 4 H), 3.08-3.15 (m, 2 H), 3.20-3.27 (m, 2 H),

3.64 (t, J ) 6.9 Hz, 2 H), 4.12 (q, J ) 7.2 Hz, 2 H), 6.34 (d, J )

9.1 Hz, 1 H), 6.65 (s, 1 H), 6.72 (dd, J ) 8.9, 2.1 Hz, 1 H), 6.87

(d, J ) 7.3 Hz, 4 H), 7.03 (d, J ) 2.0 Hz, 1 H), 7.15-7.25 (m, 10

H), 7.32-7.41 (m, 4 H), 7.45-7.51 (m, 4 H), 7.84 (d, J ) 8.3 Hz,

2 H). HRMS calcd for [C₅₂H₅₄ClNO₅SSi + H] 868.325 32; found

868.32521. Anal. (C₅₂H₅₄ClNO₅SSi) C, H, N.

Ethyl 3-[4-({2-[5-Chloro-1-(diphenylmethyl)-2-(2-hydroxyethyl)-

1H-indol-3-yl]ethyl}sulfonyl)phenyl]propanoate (131). TBAF (3.4

mL of a 1.0 M solution in THF, 3.4 mmol) was added to a solution

of silyl ether 130 (2.45 g, 2.8 mmol) and THF (0.1 M) at 0 °C.

The reaction mixture was allowed to warm to room temperature,

and after 1 h it was quenched with aqueous NH₄Cl solution.

Aqueous workup and ﬂash chromatography (10% EtOAc-hexanes)

1

afforded 131 (1.57 g, 89% yield) as a white solid. H NMR (400

MHz, CDCl₃) δ 1.24 (t, J ) 7.1 Hz, 3 H), 2.66 (t, J ) 7.7 Hz, 2

H), 2.97 (t, J ) 6.5 Hz, 2 H), 3.05 (t, J ) 7.6 Hz, 2 H), 3.12-3.19

(m, 2 H), 3.34-3.41 (m, 2 H), 3.59-3.66 (m, 2 H), 4.12 (q, J )

7.1 Hz, 2 H), 6.44 (d, J ) 8.8 Hz, 1 H), 6.76 (dd, J ) 8.9, 2.1 Hz,

1 H), 6.92 (s, 1 H), 7.04 (dd, J ) 6.7, 2.9 Hz, 4 H), 7.14 (d, J )

1.8 Hz, 1 H), 7.27-7.33 (m, 6 H), 7.43 (d, J ) 8.3 Hz, 2 H),

7.86-7.92 (m, 2 H).

3-[4-({2-[5-Chloro-2-(2-{[(2,6-diﬂuorobenzyl)sulfonyl]amino}eth-

yl)-1-(diphenylmethyl)-1H-indol-3-yl]ethyl}sulfonyl)phenyl]pro-

panoic Acid (140). Ester 139 (0.046 g, 0.058 mmol) was hydrolyzed

according to the general procedure to afford acid 140 (38 mg, 83%

yield) as a yellow solid, mp 132–135 °C. ¹H NMR (400 MHz,

CDCl₃) δ 2.56-2.68 (m, 2 H), 2.73-2.81 (m, 4 H), 2.82-2.95

(m, 2 H), 2.97-3.13 (m, 2 H), 3.18-3.38 (m, 2 H), 4.22 (s, 2 H),

6.18 (br s, 1 H), 6.39 (d, J ) 8.8 Hz, 1 H), 6.70-6.83 (m, 3 H),

6.83-6.95 (m, 2 H), 6.98-7.09 (m, 4 H), 7.27-7.36 (m, 6 H),

Ethyl 3-(4-{[2-(5-Chloro-1-(diphenylmethyl)-2-{2-[(methylsul-

fonyl)oxy]ethyl}-1H-indol-3-yl)ethyl]sulfonyl}phenyl)propanoate

3410 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

McKew et al.

7.41-7.43 (m, 1 H), 7.43-7.47 (m, J ) 8.3 Hz, 2H), 7.80-7.97

(m, 2 H). HRMS calcd for [C₄₁H₃₇ClF₂N₂O₆S₂+ H] 791.182 24;

found 791.182 57.

Rat Carrageenan Paw Edema (CPE) Model. Male Spra-

gue–Dawley rats weighing 190–250 g from Taconic Farms were

housed for 1 week prior to experimentation and fed food and water

ad libitum. The protocol for the carrageenan-induced rat paw edema

model was adapted from procedures previously described.^78,79The

volume of the left hind footpad of the rat was measured using an

Ugo Basile plethysmometer prior to dosing. Compounds 2, 111,

and 121 were dissolved at 37.5 mg/mL in Phosal vehicle.

Compound was diluted with the appropriate amount of water and

administered at 4 mL/kg. Two hours after dosing, 60 µL of 1%

carrageenan in sterile H₂O was injected subplantar into the left hind

footpad. The paw volume measurement was repeated 3 h after the

carrageenan injection. There were 10 animals per group. Inhibition

was calculated using the following formula:

Biological Procedures. All in vivo experiments were performed

in accordance with protocols approved by Wyeth’s Institutional

Animal Care and Use Committee. GLU micelle, MC-9, and rat

whole blood assays were previously described,⁴¹as were isothermal

calorimetry, human whole blood assay, and COX assays.⁴⁴

A549 COX-2 Cell Assay. A-549 cells were plated at 0.2 million

cells/well in 1 mL of F12K medium containing 2 mM L-glutamine,

1.5 g/L sodium bicarbonate, 100 units/mL penicillin, 100 µg/mL

streptomycin, and 10% FBS. After 16–24 h, the cells were washed

with PBS three times and 1 mL of medium containing 2% FBS

and 1 ng/mL IL-1ꢀ was added. The negative controls did not contain

IL-1ꢀ, and inhibitor was added to the appropriate wells. The next

day, the supernatant was collected from all wells.

The cells were then washed with medium containing 2% FBS,

IL-1ꢀ, and inhibitor where appropriate. The cells were then

incubated for 15 min with medium containing 2% FBS, IL-1ꢀ,

inhibitor, and arachidonic acid (1 µM) where appropriate. After

15 min at 37 °C, the supernatant was collected, centrifuged,

transferred to a fresh plate, and stored at –20 °C until PGE₂

production was analyzed by ELISA. By measuring the PGE₂

production that occurs in the 15 min of incubation after overnight

induction of COX-2, we were able to determine the effect of

bypassing cPLA₂R with exogenous arachidonic acid.

Pharmacokinetics in Rats. Male Sprague–Dawley rats (200–300

g, Taconic, Germantown, NY) were used for PK assessment. For

iv administration, animals (n ) 3) received a single bolus dose of

2 mg/kg in DMSO/PEG-400 (50/50) via tail vein injection. For

oral administration, rats (n ) 3) were dosed via gavage at 25 mg/

kg. Compounds were made at 37.5 mg/mL in Phosal vehicle (50%

Phosal 53 MCT, 5% Tween-80, 15% Labrasol and is q.s. to 100%

with propylene carbonate), diluted to 6.25 mg/mL with H₂O, and

then dosed at 4 mL/kg. Blood samples were collected over a period

of 24 h via jugular cannulae. Plasma concentrations of cPLA₂R

inhibitors were determined by LC/MS/MS.

percent inhibtion ) {1 - [(3 h paw volume)

- (0 h paw volume (test group)] ⁄ [(3 h paw volume)

- (0 h paw volume (vehicle group)]} × 100

The maximum inhibition effect observed is ∼50% when dosed with

naproxen po at a dose of g10 mg/kg, and the ED₅₀is deﬁned as

the dose of the cPLA₂R inhibitor that inhibits 25% of edmea, or

half-the maximal value.

Collagen Induced Arthritis (CIA) Model. Arthritis was induced

by immunization with bovine type II collagen (Chondrex, Redmond,

WA) that had been dissolved in 0.1 M acetic acid to a concentration

of 2 mg/mL. This solution was then emulsiﬁed 1:1 with either

complete Freund’s Adjuvant (Sigma Chemical Co., St. Louis, MO)

or incomplete Freund’s Adjuvant (Sigma Chemical Co., St. Louis,

MO).

An appropriate amount 2, 111, or 121 was weighed to make a

stock solution of 37.5 mg/mL Phosal vehicle. For each treatment

day over the course of 31 days the stock solution was diluted daily

with deionized water to a ﬁnal concentration of 10 mg/mL 111

and dosed at 100 mg/kg (10 mL/kg) and the compounds were dosed

b.i.d. via oral gavage.

The mice were monitored daily for signs of arthritis using the

scoring system shown below. When 10% of the mice demonstrated

signs of arthritis, all the mice were randomly assigned to treatment

groups. On the day that the animals were assigned to a treatment

group, the mice began receiving daily doses via oral gavage of

compound or the vehicle control. The oral dose administration was

conducted for 31 days; one assigned group in the oral study was

left untreated. The disease severity was scored in a blinded fashion:

no arthritis (score 0); one or two swollen digits (score 1); three or

more swollen digits or mild to moderate swelling of the entire paw

(score 2); extensive swelling of the entire paw (score 3); resolution

of swelling with ankylosis of the paw (score 4). All paws were

evaluated for each animal; therefore, the maximum score per animal

was 16.

Following euthanasia with CO₂on day 32 after 31 days of

treatment, all four paws of nine animals from each of the three

groups were placed in 10% neutral buffered formalin, decalciﬁed,

processed, parafﬁn-embedded, and prepared as standard hematoxy-

lin and eosin-stained glass slides. All slides were evaluated in a

blinded fashion by a board certiﬁed veterinary pathologist using

the following qualitative scoring system for arthritis severity: “grade

0” for no abnormal ﬁndings (normal synovial membrane at 1–3

synoviocytes thick, absence of inﬂammatory cells, and smooth

articulating cartilage surfaces); “grade 1” (synoviocyte hypertrophy,

slight synovial membrane ﬁbrosis, slight to mild inﬂammatory cell

inﬁltrates into the synovial membrane/articular capsule and/or joint

space); “grade 2” (grade 1 plus mild to moderate inﬂammatory cell

inﬁltrates, pannus formation (if present) is minimal with superﬁcial

cartilage erosion); “grade 3” (grade 2 plus marked inﬂammatory

cell inﬁltrates and ﬁbrosis, mild to severe erosion of the cartilage

extending into subchondral bone); and “grade 4” (loss of joint

integrity through erosion or destruction with bone remodeling,

massive inﬂammatory cell inﬁltrates, ﬁbrosis, and ankylosis).

Adjuvant Induced Arthritis (AIA) Model. Rats were injected

intradermally with 0.1 mL of Freund’s adjuvant-complete at the

The pharmacokinetic parameters (AUC and clearance) were

calculated with noncompartment method (WinNonlin, version 4.0,

Pharsight Corp., Mountain View, CA).

Carrageenan Air Pouch. Rats were anesthetized, and 10–20

mL of ﬁltered air was injected subcutaneously under the dorsal

skin to form a pouch. Three and six days later, the pouches were

reinﬂated with 10–15 mL of sterile air. On the seventh day, the

appropriate dose of 2, 111, 121, or Phosal vehicle (50% Phosal 53

MCT, 5% Tween-80, 15% Labrasol and is q.s. to 100% with

propylene carbonate) was administered to the rats by oral gavage.

Compound at 37.5 mg/mL in Phosal vehicle was diluted with the

appropriate amount of water and administered at 4 mL/kg. Two

hours later, 2 mL of a 1% solution of carrageenan (Viscarin

Carrageenan type GP-209NF from FMC Corporation (Philadelphia,

PA)) in saline was injected into the pouch. Six hours after the

carrageenan injection, the rats were individually sacriﬁced and the

contents of the pouch were harvested. The amount of ﬂuid recovered

was measured. An aliquot of the exudate was centrifuged at

3407.35g for 10 min, and 300 µL of each supernatant was

precipitated with 800 µL of ice-cold methanol. The samples were

well vortexed and were kept at –80 °C overnight. Before perfor-

mance of the PGE₂test, the samples were centrifuged again.

Supernatants were used directly by a dilution of 1:5 or greater in

assay buffer (supplied in the PGE₂kit) to locate the PGE₂

production within the linear range of the PGE₂standard curve (PGE₂

ELISA kit, Assay Design Inc. (Ann Arbor, MI)). Generally, the

concentration of the linear range was from 62.5 to 1000 pg/mL.

To minimize the difference in binding environments for the

standards and samples, the standard curve was generated in a 1%

solution of carrageenan that was mixed with assay buffer to the

same dilution as the samples. The approximate ED₅₀values were

extrapolated from the dose response curve for each compound.

There were six to eight mice per group.

Indole Cytosolic Phospholipase A₂R Inhibitors

Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12 3411

tail. Each milliliter contained 1 mg of Mycobacterium tuberculosis

heat-killed and dried, 0.85 mL of mineral oil, and 0.15 mL of

mannide monooleate. After 8 days the animals were randomized

into ﬁve groups, each group containing six rats. The eight groups

were dosed orally using Phosal vehicle as described above. The

animals were treated for 11 days. During the 11 treatment days,

the severity of arthritis was monitored daily. This was done using

a 0–3 scale for swelling and for erythema of the hindpaws (0 )

normal paw, 1 ) mild, 2 ) moderate, 3 ) severe). The maximum

possible score per day was 12.

Supporting Information Available: Purity data from HPLC

analysis or full combustion data for all ﬁnal compounds. This

material is available free of charge via the Internet at http://

pubs.acs.org.

Note Added in Proof. Human cPLA₂ꢁ (PLA2gIVf) was

expressed in COS-M6 cells and the cleared lysate was assayed

analogously to the cPLA₂ꢀ assay. The maximum inhibition observed

for 121 was 30% at 2 µM. In contrast, cPLA₂R assayed in parallel

was 90% inhibited at 30 nM and had an IC50 ) 8 nM.

At the end of the study, treatment day 11, the rats were

euthanized with CO₂. During necropsy, the tarsal joints were

removed and ﬁxed in 10% buffered formalin. After decalciﬁcation,

histologic sections were obtained and stained with hematoxylin and

eosin or safranin O–fast green stain. Subsequently, an examiner

blinded to the treatment groups evaluated the slides. Synovial tissue

from tarsal joints was evaluated on the basis of synovial hyperplasia

(score 0–3), ﬁbroplasia (score 0–3), inﬂammatory cell inﬁltration

(score 0–3), and pannus formation (score 0–2). Articular cartilage

was evaluated using Mankin’s histological grading system,⁶⁴based

on structure (score 0–6), cellularity (score 0–3), safranin-O staining

(score 0–4), and tidemark integrity (score 0–1).

Allergen Induced Sheep Bronchoconstriction Model. Allergic

sheep weighing 27-50 kg were used to assess efﬁcacy of test

articles. All sheep had previously been shown to develop both early

and late bronchial responses to inhaled Ascaris Suum antigen. The

sheep were conscious and were restrained in a modiﬁed shopping

cart in the prone position with their heads immobilized. After topical

anesthesia of the nasal passages with 2% lidocaine a balloon catheter

was advanced through one nostril into the lower esophagus. The

animals were intubated with a cuffed endotracheal tube through

the other nostril with a ﬂexible ﬁberoptic bronchoscope as a guide.

Animals were challenged via the airways with Ascaris Suum antigen

(Greer Diagnostics, Lenoir, NC), and breath-by-breath determination

of mean pulmonary resistance (R_L) was measured with the esoph-

ageal balloon technique as described previously.⁸⁰To assess

bronchial responsiveness (AHR), the day following allergen chal-

lenge cumulative concentration–response curves to carbachol were

generated by measuring speciﬁc lung resistance immediately after

inhalation of buffer and after each consecutive administration of

10 breaths of increasing concentrations of carbachol. The provoca-

tion test was discontinued when speciﬁc lung resistance increased

by more than 400% from the postsaline value or after the highest

carbachol concentration had been administered.

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To determine efﬁcacy by oral administration, test articles were

administered at 10 mg/kg b.i.d. on the day prior to antigen challenge

and again 2 h prior to challenge and 8 h after challenge. For oral

administration at 10 mg/kg, test articles were dissolved in Phosal

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mg/mL with water and dosed at 0.25 mL/kg. In each experiment

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Acknowledgment. The authors thank Molly Hoke, Wei

Li, Jianchang Li, and Dianne DeVincentis for the preparation

of chemical intermediates; Yelena Leathurby for help with

the AIA study; Nelson Huang, Ying Ge, Walter Massefski,

Ning Pan, and Peter Tate for analytical support; Wen Zhang,

Weili Duan, and Yajuan Zhao for assay support; Nevana

Mollova, Uma Ruat, and Elizabeth Vayntrub for providing

analytical analysis of drug concentrations; and Douglas

Shorten and Shannon Chesley for coordinating animal PK

studies. We also thank Howard Sard, Anu Mahadevan, Mario

Gonzalez, Vishnu Hegede, and Shanghao Liu of Organix,

Inc. for the preparation of chemical intermediates.

3412 Journal of Medicinal Chemistry, 2008, Vol. 51, No. 12

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5×10^–3where Xi₅₀is the concentration of the inhibitor at which 50%

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5

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)

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JM701467E

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Indole cytosolic phospholipase A2 α inhibitors: Discovery and in vitro and in vivo characterization of 4-{3-[5-chloro-2-(2-{[(3,4- dichlorobenzyl)sulfonyl]amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl} benzoic acid, efipladib

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