Synthesis and biological activity of novel thyroid hormone analogues: 5′-aryl substituted GC-1 derivatives

Article abstract of DOI:10.1016/S0968-0896(01)00284-X

Compounds that selectively modulate thyroid hormone action by functioning as isoform-selective agonists or antagonists of the thyroid hormone receptors (TRs) might be useful for medical therapy. We have synthesized a high affinity TRβ-selective agonist ligand, GC-1, and optimized the synthetic route to provide large quantities of the compound for animal testing. In addition to an improvement in efficiency, the new synthetic route offers a chemical handle for selective modification of the thyronine skeleton to produce new derivatives. To explore the effect of GC-1 core structure modifications on binding to TR isoforms and activation of transcription, we developed here an efficient and flexible route to a new series of 5'-substituted GC-1 analogues. This route relies on ortho lithiation and in situ boration of the biarylmethane compound 1, a key intermediate of the revised GC-1 synthesis, followed by Suzuki cross-coupling. Using this approach we prepared and tested eleven 5'-substituted GC-1 analogues. Substitution at the 5'-position decreased binding affinity, but retained TRβ-selectivity for most of the compounds. Transactivation assays reveal that most of these compounds function as thyroid hormone agonists, but one compound (GC-14) antagonizes the response to thyroid hormone. Copyright

Full text of DOI:10.1016/S0968-0896(01)00284-X

Bioorganic & Medicinal Chemistry 10 (2002) 333–346
Synthesis and Biological Activity of Novel Thyroid Hormone
Analogues: 50-Aryl Substituted GC-1 Derivatives
Grazia Chiellini,a Ngoc-Ha Nguyen,a James W. Apriletti,b John D. Baxterb
a,
andThomas S. Scanlan *
aDepartments of Pharmaceutical Chemistry and Cellular & Molecular Pharmacology, University of California, San Francisco,
CA 94143-0446, USA
bMetabolic Research Unit, University of California, San Francisco, CA 94143-0540, USA
Received20 June 2001; accepted1 August 2001
Abstract—Compounds that selectively modulate thyroid hormone action by functioning as isoform-selective agonists or antago-
nists of the thyroidhormone receptors (TRs) might be useful for medical therapy. We have synthesizeda high affinity TR b-selective
In addi-
2
agonist ligand, GC-1,1 andoptimizedthe synthetic route to provide large quantities of the compoundfor animal testing.
tion to an improvement in efficiency, the new synthetic route offers a chemical handle for selective modification of the thyronine
skeleton to produce new derivatives. To explore the effect of GC-1 core structure modifications on binding to TR isoforms and
activation of transcription, we developed here an efficient and flexible route to a new series of 50-substituted GC-1 analogues. This
route relies on ortho lithiation andin situ boration of the biarylmethane compound 1, a key intermediate of the revised GC-1
synthesis,2 followedby Suzuki cross-coupling. Using this approach we preparedandtestedeleven 5 0-substituted GC-1 analogues.
Substitution at the 50-position decreased binding affinity, but retained TRb-selectivity for most of the compounds. Transactivation
assays reveal that most of these compounds function as thyroid hormone agonists, but one compound (GC-14) antagonizes the
response to thyroidhormone. # 2001 Elsevier Science Ltd. All rights reserved.
Introduction
sive genes.6ꢀ8 LigandedandunligandedTRs bindat
specific cis-acting thyroidhormone response elements
(TREs), andmay bindas monomers, homodimers, or
Thyroidhormone, (T , Fig. 1), produced by deiodina-
3
tion of thyroxine (T4, Fig. 1) in peripheral tissues andby
the thyroidglan,d exerts critical influences on the
growth, development and metabolism of vertebrates.3
Lack of T3 in early human development results in
growth disturbances and severe mental retardation;4
later in life, T3 plays an important role in metabolic
balance.5 In excess, thyroidhormones may cause weight
loss, lowering of plasma lipidlevels, tachycardia, atrial
arrhythmias, andheart failure.
heterodimers with other transcription factors such as
9
the retinoidX receptor (RXR).
Like other nuclear
receptors, the TRs have three structural domains; an N-
terminal domain, a central DNA binding domain
(DBD), anda C-terminal ligandbinidng odmain
(LBD). Crystal structures of the ligand-bound TR
LBDs have been solvedrecently andreveal an internal
binding mode for the ligand.10ꢀ12
There are two TR genes designated TRa andTR b,
locatedon different chromosomes (17 and3, respec-
tively, in humans). Alternative splicing from each gene
generates at least four isoforms: TRa1, TRa2, TRb1 and
TRb2.9 The TRa1, TRa2, andTR b1 isoforms are widely
Essentially all known physiological actions of thyroid
hormone are believedto occur through thyroidhor-
mone receptors (TRs), which are members of the
nuclear hormone receptor superfamily. Members of this
superfamily are ligand-activated transcription reg-
ulators that control transcription of hormone-respon-
13ꢀ15
expressedwith characteristic tissue idstribution,
whereas TRb2 expression is largely confinedto the
anterior pituitary.16 Although thyroidhormone displays
no selectivity in binding or activation of the TR iso-
forms, synthetic analogues have been developed that are
TRb-selective agonists.17 The further development of
*Corresponding author. Tel.: +1-415-476-3620; fax: +1-415-502-
7220; e-mail: scanlan@cgl.ucsf.edu
0968-0896/02/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(01)00284-X

334
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
Figure 1.
TR isoform-selective agonists andantagonists will pro-
vide useful pharmacological probes for studying thyroid
hormone action, andmay also provide new therapeutics
for the treatment of metabolic disorders.
receptor-binding and transactivation properties of these
compounds. These analogues all bind TRs and most
retain agonist activity with TRb selectivity. However,
one compound( GC-14) was foundto have TR b-selec-
tive antagonist activity.
Comparedto steroidligands for nuclear receptors, T
3
analogue chemistry is relatively unexplored. Previous
studies have focused on structure–activity relationships
of the features of T3,18 as well as development of liver-
specific thyroidhormone agonists for treatment of
hypercholesterolemia.19,20 There are, however, struc-
tural features of T3 that present significant challenges to
chemical synthesis, andthus limit analogue design. We
initially designed and synthesized the high-affinity TRb-
selective thyroidhormone analogue, GC-1 (Fig. 1), in
an attempt to finda thyroidhormone scaffoldthat was
more synthetically accessible than T3.1 GC-1 differs
from T3 in three key respects: replacement of the ether
bridge joining the two0 rings with methylene; replace-
ment of the 3, 5, and3 iodine atoms with methyl (3,5)
andisopropyl (3 0); andreplacement of 1-amino-
propionic acidwith oxyacetic acid. These changes pro-
duce an analogue with comparable dimensions to T3 but
significantly lower molecular weight.
Results and Discussion
Rationale and design
Our interest in probing the substituent effects at the
50 position of GC-1 was basedon a crystallographic
analyses that suggestedthis wouldbe a goodposition to
introduce a large extension that would result in a ligand
with T3 antagonist activity.21 Our recently solvedstruc-
ture of the TRb LBD boundto GC-112 reveals that the
50 position of the ligandis adjacent to the loop between
helices 11 and12, andsubstituents at this position
wouldnot be accommoadtedby the ligandbinidng
cavity. In analogy to the raloxifene andtamoxifen-
22,23
boundestrogen receptor structures,
a large sub-
stituent at this position may perturb the packing of helix
12 andformation of the coactivator binding surface,
resulting in abolishment of transciptional activity from
the liganded TR.
Because the GC-1 synthesis is well suitedto generating
analogues, we are using the scaffoldto test the effects of
substitution at various positions on the scaffold. We
describe here the design and synthesis of a variety of 50-
aryl substituted GC-1 derivatives (Fig. 1), and the
We have recently optimizedour original synthesis of
GC-1 using methoxymethyl (MOM) andtriisopropylsi-
lyl (TiPS) substituents as phenolic protecting groups.2

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
335
The new route allowedus to prepare multigram quan-
tities of GC-1 andoffereda chemical handle for selective
modification of the thyronine skeleton to produce new
derivatives. Thus, this synthetic route was adopted for
the synthesis of a new series of 50-aryl GC-1 analogues,
andthe chemistry usedis outlinedin Scheme 1.
variety of aryl iodides was straightforward and provided
the desired cross-coupled products in good yield.
De-silylation of 3a–3f with tetrabutylammonium fluo-
ride generated the phenols 4a–4f, which were then
mono-alkylatedusing bromoethylacetate to give the
mono-ester 5a–5f. The desired 50-aryl substitutedthyr-
onine analogues, GC-13, GC-14, GC-19, GC-20, GC-21
and GC-22 were obtainedfrom the corresponding ester
by removal of the methoxymethyl phenolic protecting
group under acidic conditions, followed by basic sapo-
nification of the ethyl esters.
Chemical synthesis
Compounds GC-13, GC-14, GC-19, GC-20, GC-21, and
GC-22 were preparedas describedin Scheme 1.
24
metalation andin situ boration
Ortho
of the biarylmethane
compound 1, which was a key intermediate in the
revisedsynthesis of GC-1,2 using n-butyllithium as the
base andtriisopropylborate as the electrophile, in a 2:1
THF/hexanes solvent mixture, generates the boronic
acid 2. Suzuki coupling of 2 with a variety of aryl
halides produced a series of 50-aryl analogues 3a–3f. The
lithiation directed by the MOM group turned out to be
a difficult step; the rate of lithiation was affected greatly
by the polarity of the solvent. The best conditions we
foundwere using a 2:1 THF/hexanes as the reaction
solvent. Under these conditions the lithiation and sub-
sequent boration proceeded in good overall yield. The
subsequent Suzuki cross-coupling reaction with a
The 40-carboxymethyl-amino analogue, GC-15 andthe
urea analogue GC-16 were preparedfrom the inter-
mediate compound 3b as shown in Scheme 2. The nitro
group reduction of 3b by iron/acetic acidledto the ani-
line 6. Selective removal of the triisopropylsilyl phenolic
protecting group of 6 followedby alkylation generated
the bis-ester 7, which after removal of the meth-
oxymethyl phenolic protecting group was subjected
to alkaline hydrolysis to yield GC-15. Reaction of 6
with phenylisocyanate generatedthe phenyl urea deri-
vative 8, which was elaboratedto GC-16 as described
above.
0
Scheme 1. Synthetic route usedfor the preparation of 5 -aryl substituted GC-1 analogues: GC-13, GC-14, GC-19, GC-20, GC-21 and GC-22.

336
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
Scheme 2. Synthesis of GC-15 and GC-16.
Scheme 3. Synthesis of GC-17 and GC-18.

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
337
Analogues GC-17 and GC-18 were preparedas outlined
in Scheme 3. N-alkylation of 6 with 1-bromo-2-butyne
afforded the acetylene derivative 9, which was elabo-
ratedto the final compound GC-17 as described above.
Nitro group reduction of 5b gave aniline 10, which was
elaboratedto GC-18 as described above.
with at least a two orders of magnitude reduced affinity.
Although binding is impaired, the TRb selectivity of
GC-1 is retainedby most of the 5 -substitutedcom-
pounds. This result is consistent with structural data,12
which suggests the molecular determinant of selectivity is
locatedon the oxyacetic acidside chain at the opposite
endof the thyronine core structure.
0
The guanidine derivative GC-23 was preparedas out-
linedin Scheme 4. Guanylation of 6 with Pmc-S-
methylisothiourea in the presence of triethylamine and
Hg(ClO4)2 in refluxing THF ledto the corresponding
Pmc-protectedguanidine 11.25 De-silylation of 11 fol-
lowedby alkylation with tert-butylchloroacetate gave
compound 12, which upon acidic hydrolysis provided
GC-23.
To examine the transcriptional transactivation proper-
ties of the compounds, HeLa cells were co-transfected
with an expression plasmidfor TR b1 or TRa1, together
with a TRE-driven luciferase reporter plasmid, and
luciferase expression was determined at different con-
centrations of added ligand. All of the compounds
tested, except GC-14, were foundto be full or nearly full
agonists of TRb1 activation andthe EC
values for
50
each compoundare shown in Table 1. Two of the com-
pounds that had reasonably high affinity for TRa1 (GC-
13, GC-17) were foundto be full agonists of TR a1, but
retainedactivation selectivity for TR b1 (Table 1). The
majority of the compounds were not tested in the TRa1
activation assay because their relatively poor affinity
andpotency for TR a1 made it difficult to obtain com-
plete dose–response curves. The compound GC-14 dis-
playedweak partial agonism of reporter activation with
both TRb1 andTR a1; the maximum activation by GC-
14 was approximately 20 and35% comparedto GC-1
for TRb1 andTR a1, respectively (Table 1). We next
testedwhether GC-14 couldcompetitively block TR b1
activation by T3 in a dose-dependent manner and found
that GC-14 did indeed antagonize the activation of 1 nM
Receptor binding and transactivation properties
The human TRa andTR b binding affinities for the 50-
aryl substituted GC-1 analogues GC-13–GC-23 are
shown in Table 1. As a comparison, the parent com-
pound GC-1 was also tested. Binding affinity was mea-
sured with an in vitro radioligand-displacement assay,
where recombinant human TRa1 andTR b1 were ana-
lyzed independently using a fixed concentration of
[
125I]T3 in the presence of a range of concentrations of
each analogue. In general, substitution at the 50-position
results in a decreased binding affinity for both TRa and
TRb comparedto the parent compound GC-1. The
parent compoundhas a KD of 0.10 nM for TRb
whereas all of the 50-substitutedcompounds bindTR
b
Scheme 4. Synthesis of GC-23.

338
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
T3 down to the maximum level of activation observed
with GC-14 alone (Table 1 andFig. 2). Under these
conditions, the IC50 value of this antagonism by GC-14
was 700 nM (Table 1). A similar competition experiment
of GC-14 is not relatedto the size of the para-sub-
stituent appended to the 5-phenyl. For example, GC-16
and GC-17 bear significantly larger phenyl substituents
than the nitro of GC-14 andthey are both agonists with
tighter binding affinity to TRb than GC-14. Moreover,
the data indicate that the para position of the nitro
group in GC-14 is critical; the meta andortho analogues
(GC19 and GC-20) are agonists andthe ortho analogue
GC-20 is one of the more potent agonists within this
series. The data further indicate that for this series of
was performedwith GC-14 andTR a1, andthe IC
value of T3 antagonism was 5000 nM (Table 1), further
50
demonstrating the TRb selectivity of the compound.
The structure–activity relationship (SAR) data provided
in Table 1 suggests that the partial agonism/antagonism
Table 1. 50-Aryl substitutedGC-1 analogues TR b1 andTR a1 binding affinities and transcriptional activity
R
KDꢁSE (nM)a
% TRb1
TRb1 EC50
% TRa1
TRa1 EC50
(IC50) (nM)
d
activationb
(IC50
)
(nM)
activationf
hTRb1
hTRa1
GC-1
H
0.1ꢁ0.02
30ꢁ13
1.8ꢁ0.2
100
99
7
100
99
45
GC-13
170ꢁ10
200ꢁ60
140ꢁ15
140ꢁ15
42ꢁ8
240
680e
750
900
GC-14
GC-15
GC-16
GC-17
GC-18
GC-19
GC-20
GC-21
GC-22
GC-23
35ꢁ12
23ꢁ3
18
72
35
n.d.
n.d.
100
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
5000e
n.d.
n.d.
4000
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
45ꢁ20
12ꢁ8
86
900
79
650
21ꢁ5
150ꢁ80
680ꢁ380
170ꢁ120
120ꢁ10
200ꢁ10
2300ꢁ300
100
100
100
100
43c
57c
550
230ꢁ30
22ꢁ10
16ꢁ2
1120
660
630
38ꢁ6
550
320ꢁ20
4950
aThe KD and standard error (SE) values were calculated by fitting the competition data to the equations of Swillens27 andusing the Graph-Pad
Prism computer program.
bHeLa cells were co-transfectedwith a TR b1 expression vector anda TRE-luciferase reporter plasmid. Luciferase activity is expressedas a percent of
the TRb1 response with 10ꢀ9 M T3.
cCompound GC-22 and GC-23 testedin competition experiments with T (10ꢀ9M) were not able to antagonize T3 activation in a dose-dependent
3
manner.
dThe EC50 value is the concentration of ligandrequiredfor half-maximun activation, whereas the IC 50 value is the concentration of ligandrequired
for half-maximun inhibition. EC50 values of transcriptional activation were determined graphically from dose response curves. IC50 values were
determined graphically from dose-response curves obtained in competition experiments. In these experiments a fixed concentration of T3 (10ꢀ9 M)
was added to the cells along with a range of concentrations of the selected compound. See experimental for more details.
eThese are IC50 values on TRb1 andTR a1 respectively.
fHeLa cells were co-transfectedwith a TR a1 expression vector anda TRE-luciferase reporter plasmid. Luciferase activity is expressedas a percent of
the TRa1 response with 10ꢀ9 M T3.

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
339
Experimental
General
Proton andcarbon-13 nuclear magnetic resonance
spectra (1H NMR and 13C NMR) were recorded on
either General Electric QE 300 (300 MHz) or Varian
Unity 400 MHz spectrometers, using CDCl3 or MeOD
as solvent. Chemical shifts were reportedas parts per
million downfield from an internal tetramethylsilane
standard (d=0.0 for 1H) or from solvent references.
NMR coupling constants are reportedin Hertz. 13C
NMR were determined using 13C pulse sequence para-
meters. High-resolution mass spectrometry was per-
formedby the National Bio-Organic, Biomedical Mass
Spectrometry Resource at UCSF. Flash chromato-
graphy on crude products was performed using 230–400
mesh silica gel (Aldrich Chemical Co.). Purity of com-
pounds was determined by TLC using commercial silica
gel plates (Alltech, AlugramR Sil G/UV 254) andby 1H
NMR andHRMS.
Figure 2. Transcription activation profile for GC-14 with TRb.
Human uterine cervix cancer (HeLa) cells were trasfectedwith 0.5 mg
of the TRb expression vector and10 mg of the DR4-Luciferase
reporter gene andwere treatedwith indicatedconcentrations of GC-14
alone (triangle) or GC-14 in the presence of 10ꢀ9 M T3 (circle) for 24
h. Values are the meanꢁSD for three separate experiments, andare
expressedas a percent of the TR b response with 10-9 M T3 , which is
set at 100%.
Glassware was oven- or flame-dried prior to use. Meth-
ylene Chloride (anhydrous), tetrahydrofuran (anydrous)
andreagents were purchasedfrom Aldrich Chemical
Co. andusedwithout further purification. Reactions
were performedunder Argon inert atmosphere.
compounds, the electronic properties of the GC-14 nitro
group are also critical as the isosteric carboxylate (GC-
21), carboxyamide (GC-22), andguanidinium ( GC-23)
analogues all function as agonists. The SAR data pre-
sently in handsuggest a very restrictive set of structural
criteria for antagonism within this series mandating an
absolute requirement for a nitro group in a particular
position on the 50-phenyl ring.
Thyroid hormone receptor ligand binding assays
Full-length hTRa1 andhTR b1 were produced using the
TNT coupledreticulocyte lysate system (Promega). The
ligand binding domains of hTRa1 andhTR b1 were
expressedin Escherichia coli andpurifiedto greater than
95% homogeneity as described previously.26 Competi-
tion ligand binding affinities were determined using
1nM [125I]T3 in gel filtration binding assays as descri-
bed.26 The KD andstandarderror (SE) values were cal-
culatedby fitting the competition data to the equations
of Swillens27 andusing the Graph-PadPrism computer
program (GraphPadSoftware, Inc.).
Conclusions
0
We have prepareda new series of 5 -substitutedthyroid
hormone analogues using the TRb-selective thyr-
omimetic GC-1 as the core element. These compounds
were designed to not completely fit into the ligand
binding cavity of the TR, and therefore to perturb
potentially agonist-induced structure of the TR. All of
the compounds within the series show reduced binding
affinity for TRs comparedto GC-1, yet like GC-1, they
bindTR b in preference to TRa. Surprisingly, all of the
compounds in the series function as T3 agonists in a
TRE-driven reporter gene assay with the exception of
one compound, GC-14. GC-14 shows weak partial ago-
nist activity by itself, andin competition experiments
with T3, it is able to antagonize T3 activation of TRa1
andTR b1 in a dose-dependent manner. GC-14 antag-
onizes the T3 response more potently with TRb1 than
with TRa1 indicating that the TRb selectivity of the
parent compound GC-1 is retainedin GC-14. The
available SAR data indicates that the antagonistic
property of GC-14 is dictated by the nitro group
Transcriptional activation assay
Human uterine cervix cancer (HeLa) cells were man-
tainedin culture andtransfectedas edscribedpre-
viously.28,29 Briefly, cells were collectedandresuspended
in Dulbecco’s PBS (0.5 mL/transfection) containing
0.1% dextrose, 10 mg/mL bioprene, and mixed with 0.5
mg of the appropriate TR expression vector and10 mg of
the reporter plasmid. The TR expression vector con-
tainedeither the full length human TR b1 or human
TRa1 under the control of the cytomegalovirus pro-
moter, CMVTRb1 andCMVTR a1, respectively. The
reporter plasmidcontaineda synthetic TR response
element (DR-4) containing two copies of a direct repeat
spacedby four nucleotides (AGGTCA-cagg-AGGTCA)
clonedimmediately upstream of a minimal ( ꢀ32/+45)
thymidine kinase (tk) promoter linked to luciferase
coding sequence. Cells (0.8ꢂ107) were electroporated
using a Bio-Radgene pulser at 350V and960 micro-
farads, pooled in growth medium (DME H-21 with
10% charcoal-treated, hormone stripped, newborn
bovine serum), and plated in 6-well dishes. Compounds
0
attachedto the 5 -phenyl extension, andthat the size,
position, andelectronic properties of this nitro group
are all essential for the observedactivity.

340
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
were added to the cell culture media as ethanol solutions
so as to yielda final ethanol concentration of 0.1%.
After incubation for 24 h at 37 ꢃC cells were detached
with 1 mL of calcium-magnesium-free PBS, 1 mM
was effectedusing the general procedure to afford370
mg (68%) of the title compoundas a colorless oil. 1H
NMR (300 MHz, CDCl3) d 1.1 (d, 18H, J=6.9 Hz),
1.16 (d, 6H, J=6.9 Hz), 1.23 (m, 3H), 2.20 (s, 6H), 3.18
(s, 3H), 3.37 (heptet, 1H, J=6.9 Hz), 3.96 (s, 2H), 4.52
(s, 2H), 6.61 (s, 2H), 6.71 (s, 1H), 6.98 (s, 1H), 7.63 (d,
2H, J=8.7 Hz), 8.22 (d, 2H, J=8.7 Hz); 13C NMR
(300 MHz, CDCl3) d 156.2, 152.6,147.3, 142.7, 138.4,
137.3, 135.5, 135.3, 128.3, 126.1, 125.5, 124.1, 122.4,
118.3, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3, 14.8, 12.1.
ꢃ
EDTA, pre-warmedat 37 C, andtransferredto 1.5 mL
Eppendorf tubes. Cells were pelleted by centrifugation
in a microfuge for 1 min at room temperature. The
supernatants were aspiratedandthe pellets were lysed
by addition of 120 mL of Tris–Cl 0.25 M pH 7.6, 0.1%
Triton. After resuspension by vortexing for 5–10 s, the
lysates were pelletedby centrifugation in a microfuge
for 5 min at rt. Cellular lysates (100 mL) were then
Triisopropil-[4-(5-isopropyl-6-methoxymethoxy-30-nitro-
30
assayedfor luciferase activity as previously described.
biphenyl-3ylmethyl)-3,5-dimethyl-phenoxy]-silane
(3c).
The coupling of 3-iodonitrobenzene with phe-
nylboronic acidwas effectedusing the general procedure
to afford380 mg (65%) of the title compoundas a col-
Chemistry
{50-[2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl]-3-iso-
propyl-2-methoxymethoxy-phenyl}-boronic acid (2). A
solution of 1 (0.5 g, 1.06 mmol ) in 5 mL of a 2:1 mix-
ture of dry tetrahydrofuran/hexanes was treated under
an inert atmosphere with 2.0 equiv of n-butyllithium in
hexane andthe mixture was stirred2 h at rt to give a
cloudy white suspension. Triisopropyl borate (0.3 mL,
1.2 mmol) was added and the mixture was stirred 1 h at
room temperature. The reaction mixture was quenched
by pouring into 1 N HCl aq, extractedwith ethyl ace-
tate, dried and filtered. The crude boronic acid 2 was
usedin subsequent Suzuki coupling reactions without
further purification.
orless oil. H NMR (300 MHz, CDCl3) d 1.1 (d, 18H,
1
J=6.9 Hz), 1.18 (d, 6H, J=6.9 Hz), 1.24 (m, 3H), 2.19
(s, 6H), 3.18 (s, 3H), 3.36 (heptet, 1H, J=6.9 Hz), 3.97
(s, 2H), 4.53 (s, 2H), 6.61 (s, 2H), 6.74 (s, 1H), 6.94 (s,
1H), 7.52 (t, 1H, J=8.0 Hz), 7.77 (d, 1H, J=8.0 Hz),
8.15 (d, 1H, J=8.0), 8.37 (s, 1H); 13C NMR (300 MHz,
CDCl3) d 156.2, 152.6,148.9, 138.4, 137.5, 137.3, 135.5,
135.3, 133.5, 129.9, 126.1, 125.5, 122.5, 122.4, 118.3,
101.3, 50.2, 28.9, 24.7, 22.4, 15.3, 14.8, 12.2.
Triisopropil-[4-(5-isopropyl-6-methoxymethoxy-20-nitro-
biphenyl-3ylmethyl)-3,5-dimethyl-phenoxy]-silane (3d).
The coupling of 2-iodonitrobenzene with phe-
nylboronic acidwas effectedusing the general procedure
to afford435 mg (75%) of the title compoundas a col-
General procedure for Suzuki coupling of aryl iodines
(3a–f)
1
orless oil. H NMR (300 MHz, CDCl3) d 1.1 (d, 18H,
J=6.9 Hz), 1.16 (d, 6H, J=6.9 Hz), 1.23 (m, 3H), 2.18
(s, 6H), 3.0 8 (s, 3H), 3.27 (heptet, 1H, J=6.9 Hz), 3.95
(s, 2H), 4.51 (s, 2H), 6.60 (s, 2H), 6.63 (s, 1H), 6.97 (s,
1H), 7.40 (d, 1H, J=7.6 Hz), 7.43 (m, 1H), 7.56 (m,
1H), 7.90 (d, 1H, J=8.0); 13C NMR (300 MHz, CDCl3)
d 156.2, 152.6, 147.3, 138.4, 137.3, 135.5, 135.3, 135.1,
131.7, 128.3, 126.1, 124.1, 122.4, 118.3, 101.3, 50.2, 28.9,
24.7, 22.4, 15.3, 14.8, 12.2.
A stirredmixture of the appropriate aryl iodine (1.0
mmol), Pd2(dba)3.CHCl3 (34.7 mg, 0.03 mmol) in tolu-
ene (25 mL) under argon was successively treated with
the phenyl boronic acid 2 (565.0 mg, 1.1 mmol), dis-
solvedin a minimun volume of EtOH, and2 M Cs 2CO3
(1.1 mL). The resulting mixture was heatedat reflux for
8 h, cooled, subjected to filtration. The filtrate was eva-
porated to dryness in vacuo and the residue was treated
with satdNaCl solution. The resulting mixture was
extractedwith CH 2Cl2, dried (MgSO4), filtered, and
concentratedin vacuo. The crude material was purified
by flash column chromatography on silica gel.
50-[2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl]-30-iso-
propyl-20-methoxymethoxy-biphenyl-4-carboxylic
acid
(3e). The coupling of 4-iodobenzoic acid with phe-
nylboronic acidwas effectedusing the general procedure
to afford390 mg (71%) of the title compoundas a col-
1
Triisopropil-[4-(5-isopropyl-6-methoxymethoxy-biphenyl-
3ylmethyl)-3,5-dimethyl-phenoxy]-silane (3a). The cou-
pling of iodobenzene with phenylboronic acid was
effectedusing the general procedure to afford382 mg
(70%) of the title compoundas a colorless oil. 1H NMR
(300 MHz, CDCl3) d 1.1 (d, 18H, J=6.9 Hz), 1.16 (d,
6H, J=6.9 Hz), 1.23 (m, 3H), 2.20 (s, 6H), 3.24 (s, 3H),
3.39 (heptet, 1H, J=6.9Hz), 3.95 (s, 2H), 4.49 (s, 2H),
6.59 (s, 2H), 6.78 (s, 1H), 6.99 (s, 1H), 7.22 (m, 1H), 7.32
(m, 2H), 7.48 (d, 2H); 13C NMR (300 MHz, CDCl3) d
156.2, 152.6, 138.4, 137.3, 136.6, 135.5, 135.3, 129.0,
127.4, 126.1, 125.5, 122.4, 118.3, 101.3, 50.2, 28.9, 24.7,
22.4, 15.3, 14.8, 12.2.
orless oil. H NMR (300 MHz, CDCl3) d 1.1 (d, 18H,
J=6.9 Hz), 1.16 (d, 6H, J=6.9 Hz), 1.23 (m, 3H), 2.21
(s, 6H), 3.19 (s, 3H), 3.39 (heptet, 1H, J=6.9 Hz), 3.97
(s, 2H), 4.53 (s, 2H), 6.61 (s, 2H), 6.76 (s, 1H), 6.94 (s,
1H), 7.60 (d, 2H, J=8.0 Hz), 8.12 (d, 2H, J=8.0 Hz);
13C NMR (300 MHz, CDCl3) d 172.0, 156.2, 152.6,
141.8, 138.4, 137.3, 135.5, 135.3, 130.6, 129.5, 127.3,
126.1, 122.4, 118.3, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3,
14.8, 12.0.
50-(2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl)-30-iso-
propyl-20-methoxymethoxy-biphenyl-4-carboxylic
acid
amide (3f). The coupling of 4-bromobenzamide with
the phenyl boronic acid 6 was effectedusing the general
procedure with 3.0 mol% Pd2(dba)3.CHCl3 and2 M
Cs2CO3 to afford200 mg (70%) of the title compound
Triisopropil-[4-(5-isopropyl-6-methoxymethoxy-4-nitro-bi-
phenyl-3ylmethyl)-3,5-dimethyl-phenoxy]-silane (3b). The
coupling of 4-iodonitrobenzene with phenylboronic acid
1
as a colorless oil. H NMR (300 MHz, CDCl3) d 1.1 (d,

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
341
18H, J=6.9 Hz), 1.18 (d, 6H, J=6.9 Hz), 1.25 (m, 3H),
2.18 (s, 6H), 3.20 (s, 3H), 3.39 (heptet, 1H, J=6.9 Hz),
3.95 (s, 2H), 4.50 (s, 2H), 6.60 (s, 2H), 6.74 (s, 1H), 6.92
(s, 1H), 7.55 (d, 2H, J=8.0 Hz), 7.81 (d, 2H, J=8.0
Hz); 13C NMR (300 MHz, CDCl3) d 169.7, 156.2, 152.6,
140.8, 138.4, 137.3, 135.5, 135.3, 132.6, 127.8, 127.5,
126.1, 122.4, 118.3, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3,
14.8, 12.2.
4-[5-Isopropyl-6-methoxymethoxy-20-nitro-biphenyl-3-yl-
methyl)-3,5-dimethyl-phenol (4d). Compound 3d (150
mg, 0.25 mmol) andBu NF (0.315 mL, 1.0 M in THF)
4
were combinedin a roundbottom flask. Deprotection
was determined to be nearly instantaneous by TLC. The
reaction mixture was diluted with ethyl acetate (25 mL)
andwashedwith water (2 ꢂ25 mL) andbrine (30 mL),
dried, and concentrated. The crude product was purified
by flash column chromatography (80:20 hexane/ethyl
acetate) to yield 4d (95.0 mg, 0.20 mmol, 85%). 1H
NMR (300 MHz, CDCl3) d 1.18 (d, 6H, J=6.9 Hz),
2.20 (s, 6H), 3.11 (s, 3H), 3.32 (heptet, 1H, J=6.9 Hz),
3.95 (s, 2H), 4.52 (s, 2H), 6.56 (s, 2H), 6.63 (s, 1H), 6.97
(s, 1H), 7.41 (d, 1H, J=7.6 Hz), 7.45 (m, 1H), 7.56 (m,
1H), 7.92 (d, 1H, J=8.0); 13C NMR (300 MHz, CDCl3)
d 156.2, 154.6, 147.3, 138.9, 137.0, 135.5, 135.3, 135.1,
131.7, 128.3, 126.1, 124.1, 122.4, 113.9, 101.3, 50.2, 28.9,
24.7, 22.4, 15.3.
4-[5-Isopropyl-6-methoxymethoxy-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenol (4a). Compound 3a (137 mg, 0.25
mmol) andBu 4NF (0.315 mL, 1.0 M in THF) were
combinedin a roundbottom flask. Deprotection was
determined to be nearly instantaneous by TLC. The
reaction mixture was diluted with ethyl acetate (25 mL)
andwashedwith water (2 ꢂ25 mL) andbrine (30 mL),
dried, and concentrated. The crude product was purified
by flash column chromatography (80:20 hexane/ethyl
acetate) to yield 4a (90.0 mg, 0.24 mmol, 95%) 1H
NMR (300 MHz, CDCl3) d 1.20 (d, 6H, J=6.9 Hz),
2.20 (s, 6H), 3.25 (s, 3H), 3.44 (heptet, 1H, J=6.9 Hz),
3.95 (s, 2H), 4.50 (s, 2H), 6.53 (s, 2H), 6.75 (s, 1H), 6.94
(s, 1H), 7.28 (m, 1H), 7.37 (m, 2H), 7.48 (d, 2H); 13C
NMR (300 MHz, CDCl3) d 156.2, 154.6, 138.9, 137.0,
136.6, 135.5, 135.3, 129.0, 127.4, 126.1, 125.5, 122.4,
113.9, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3.
50 -(4-Hydroxy-2,6-dimethyl-benzyl)-30-isopropyl-20-meth-
oxymethoxy-biphenyl-4-carboxylic acid (4e). Compound
3e (148 mg, 0.25 mmol) andBu 4NF (0.315 mL, 1.0 M in
THF) were combinedin a roundbottom flask. Depro-
tection was determined to be nearly instantaneous by
TLC. The reaction mixture was diluted with ethyl ace-
tate (25 mL) andwashedwith water (2 ꢂ25 mL) and
brine (30 mL), dried, and concentrated. The crude pro-
duct was purified by flash column chromatography
(80:20 hexane/ethyl acetate) to yield 4e (96.0 mg, 0.22
4-[5-Isopropyl-6-methoxymethoxy-40-nitro-biphenyl-3-yl-
methyl)-3,5-dimethyl-phenol (4b). Compound 3b (150
mg, 0.25 mmol) andBu NF (0.315 mL, 1.0 M in THF)
4
1
mmol, 90%). H NMR (300 MHz, CDCl3) d 1.21 (d,
were combinedin a roundbottom flask. Deprotection
was determined to be nearly instantaneous by TLC. The
reaction mixture was diluted with ethyl acetate (25 mL)
andwashedwith water (2 ꢂ25 mL) andbrine (30 mL),
dried, and concentrated. The crude product was purified
by flash column chromatography (80:20 hexane/ethyl
acetate) to yield 4b (100.0 mg, 0.23 mmol, 95%) 1H
NMR (300 MHz, CDCl3) d 1.21 (d, 6H, J=6.9 Hz),
2.20 (s, 6H), 3.19 (s, 3H), 3.37 (heptet, 1H, J=6.9 Hz),
3.96 (s, 2H), 4.53 (s, 2H), 6.55 (s, 2H), 6.70 (s, 1H), 7.03
(s, 1H), 7.63 (d, 2H, J=8.7 Hz), 8.22 (d, 2H, J=8.7
Hz); 13C NMR (300 MHz, CDCl3) d 156.2, 154.6, 147.3,
142.7, 138.9, 137.0, 135.5, 135.3, 128.3, 126.1, 125.5,
124.1, 122.4, 113.9, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3.
6H, J=6.9 Hz), 2.19 (s, 6H), 3.18 (s, 3H), 3.40 (heptet,
1H, J=6.9 Hz), 3.95 (s, 2H), 4.51 (s, 2H), 6.56 (s, 2H),
6.71 (s, 1H), 6.99 (s, 1H), 7.54 (d, 2H, J=8.0 Hz), 8.09
(d, 2H, J=8.0 Hz); 13C NMR (300 MHz, CDCl3) d
172.0, 156.2, 154.6, 141.8, 138.9, 137.0, 135.5, 135.3,
130.6, 129.5, 127.3, 126.1, 122.4, 113.9, 101.3, 50.2, 28.9,
24.7, 22.4, 15.3.
50-(4-Hydroxy-2,6-dimethyl-benzyl)-30-isopropyl-20-meth-
oxymethoxy-biphenyl-4-carboxylic acid amide (4f).
Compound 3f (150 mg, 0.25 mmol) andBu NF (0.315
4
mL, 1.0 M in THF) were combinedin a roundbottom
flask. Deprotection was determined to be nearly instan-
taneous by TLC. The reaction mixture was diluted with
ethyl acetate (25 mL) andwashedwith water (2 ꢂ25 mL)
and brine (30 mL), dried, and concentrated. The crude
product was purified by flash column chromatography
(80:20 hexane/ethyl acetate) to yield 4f (98.0 mg, 0.22
4-[5-Isopropyl-6-methoxymethoxy-30-nitro-biphenyl-3-yl-
methyl)-3,5-dimethyl-phenol (4c). Compound 3c (150
mg, 0.25 mmol) andBu NF (0.315 mL, 1.0 M in THF)
4
1
were combinedin a roundbottom flask. Deprotection
was determined to be nearly instantaneous by TLC. The
reaction mixture was diluted with ethyl acetate (25 mL)
andwashedwith water (2 ꢂ25 mL) andbrine (30 mL),
dried, and concentrated. The crude product was purified
by flash column chromatography (80:20 hexane/ethyl
mmol, 90%). H NMR (300 MHz, CDCl3) d 1.20 (d,
6H, J=6.9 Hz), 2.19 (s, 6H), 3.20 (s, 3H), 3.40 (heptet,
1H, J=6.9 Hz), 3.93 (s, 2H), 4.50 (s, 2H), 6.56 (s, 2H),
6.70 (s, 1H), 6.99 (s, 1H), 7.55 (d, 2H, J=8.0 Hz), 7.81
(d, 2H, J=8.0 Hz); 13C NMR (300 MHz, CDCl3) d
169.7, 156.2, 154.6, 140.8, 138.9, 137.0, 135.5, 135.3,
132.6, 127.8, 127.5, 126.1, 122.4, 113.9, 101.3, 50.2, 28.9,
24.7, 22.4, 15.3.
1
acetate) to yield 4c (100.0 mg, 0.22 mmol, 90%). H
NMR (300 MHz, CDCl3) d 1.19 (d, 6H, J=6.9 Hz),
2.21 (s, 6H), 3.16 (s, 3H), 3.38 (heptet, 1H, J=6.9 Hz),
3.97 (s, 2H), 4.53 (s, 2H), 6.56 (s, 2H), 6.73 (s, 1H), 6.99
( s, 1H), 7.54 (t, 1H, J=8.0 Hz), 7.78 (d, 1H, J=7.6
Hz), 8.15 (d, 1H, J=8.0), 8.36 (s, 1H); 13C NMR
(300 MHz, CDCl3) d 156.2, 154.6, 148.9, 138.9, 137.5,
137.0, 135.5, 135.3, 133.5, 129.9, 126.1, 125.5, 122.5,
122.4, 113.9, 101.3, 50.2, 28.9, 24.7, 22.4, 15.3.
[4-(5-Isopropyl-6-methoxymethoxy-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenoxy]-acetic acid ethyl ester (5a). To
cesium carbonate (334.0 mg, 1.02 mmol) and 4a (80.0
mg, 0.20 mmol) in 5 mL of DMF was added ethyl-
bromoacetate (0.023 mL, 0.20 mmol). The reaction
mixture was stirredfor 30 min at room temperature,

342
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
pouredinto 15 mL of cold1 N HCl, andextractedwith
ethyl acetate (3 10 mL). The combinedorganic portions
were dried (MgSO4) andevaporatedto yield100 mg of
crude, which was purified using flash column chroma-
tography (silica gel, 90:10 hexane/ethyl acetate) to yield
mixture was stirredfor 30 min at room temperature,
pouredinto 15 mL of cold1 N HCl, andextractedwith
ethyl acetate (3ꢂ10 mL). The combinedorganic por-
tions were dried (MgSO4) andevaporatedto yield100
mg of crude, which was purified using flash column
chromatography (silica gel, 90:10 hexane/ethyl acetate)
1
5a (88.0 mg, 0.19 mmol, 90%). H NMR (300 MHz,
CDCl3) d 1.20 (d, 6H, J=6.9 Hz), 1.29 (t, 3H, J=7.2
Hz), 2.20 (s, 6H), 3.25 (s, 3H), 3.44 (heptet, 1H, J=6.9
Hz), 3.95 (s, 2H), 4.27 (q, 2H, J=7.2 Hz), 4.50 (s, 2H),
4.61 (s, 2H), 6.60 (s, 2H), 6.72 (s, 1H), 6.93 (s, 1H), 7.29
(m, 1H), 7.35 (m, 2H), 7.46 (d, 2H); 13C NMR
(300 MHz, CDCl3) d 159.3.6, 156.2, 138.5, 136.7, 136.6,
135.5, 135.3, 129.0, 127.4, 126.1, 125.5, 122.4, 112.3,
101.3, 75.6, 59.5, 50.2, 28.9, 24.7, 22.4, 15.3, 13.6.
to yield5d(98.0 mg, 0.19 mmol, 90%).
1H NMR
(300 MHz, CDCl3) d 1.18 (d, 6H, J=6.9 Hz), 1.27 (t,
3H, J=7.2 Hz), 2.20 (s, 6H), 3.08 (s, 3H), 3.29 (heptet,
1H, J=6.9 Hz), 3.97 (s, 2H), 4.13 (q, 2H, J=7.2 Hz),
4.52 (s, 2H), 4.59 (s, 2H), 6.57 (s, 2H), 6.60 (s, 1H), 7.01
(s, 1H), 7.41 (d, 1H, J=7.6 Hz), 7.44 (m, 1H), 7.58 (m,
1H), 7.90 (d, 1H, J=8.0); 13C NMR (300 MHz, CDCl3)
d 159.3, 156.2, 147.3, 138.5, 136.7, 135.5, 135.3, 135.1,
128.3, 126.1, 125.5, 122.4, 112.3, 101.3, 75.6, 59.5, 50.2,
28.9, 24.7, 22.4, 15.3, 13.6.
[4-(5-Isopropyl-6-methoxymethoxy-40-nitro-biphenyl-3-yl-
methyl)-3,5-dimethyl-phenoxy]-acetic acid ethyl ester
(5b). To cesium carbonate (334.0 mg, 1.02 mmol) and
4b (90 mg, 0.20 mmol) in 5 mL of DMF was added
ethylbromoacetate (0.023 mL, 0.20 mmol). The reaction
mixture was stirredfor 30 min at rt, pouredinto 15 mL
of cold1 N HCl, andextractedwith ethyl acetate (3 ꢂ10
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield100 mg of crued,
which was purifiedusing flash column chromatography
(silica gel, 90:10 hexane/ethyl acetate) to yield 5b (98.0
50-(4-Ethoxycarbonylmethoxy-2,6-dimethyl-benzyl)-30-iso-
propyl-2-methoxymethoxy-biphenyl-4-carboxylic
acid
(5e). To cesium carbonate (334.0 mg, 1.02 mmol) and
4e (87.0 mg, 0.20 mmol) in 5 mL of DMF was added
ethylbromoacetate (0.023 mL, 0.20 mmol). The reaction
mixture was stirredfor 30 min at rt, pouredinto 15 mL
of cold1 N HCl, andextractedwith ethylacetate (3 10
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield100 mg of crued,
which was purifiedusing flash column chromatography
(silica gel, 90:10 hexane/ethyl acetate) to yield 5e (95.0
1
mg, 0.19 mmol, 90%). H NMR (300 MHz, CDCl3) d
1.21 (d, 6H, J=6.9 Hz), 1.29 (t, 3H, J=7.2 Hz), 2.23 (s,
6H), 3.19 (s, 3H), 3.39 (heptet, 1H, J=6.9 Hz), 3.98 (s,
2H), 4.27 (q, 2H, J=7.2 Hz), 4.53(s, 2H), 4.61 (s, 2H),
6.64 (s, 2H), 6.67 (s, 1H), 7.02 (s, 1H), 7.63 (d, 2H,
J=8.7 Hz), 8.23 (d, 2H, J=8.7 Hz); 13C NMR
(300 MHz, CDCl3) d 159.3, 156.2, 147.3, 142.7, 138.5,
136.7, 135.5, 135.3, 128.3, 126.1, 125.5, 124.1, 122.4,
112.3, 101.3, 75.6, 59.5, 50.2, 28.9, 24.7, 22.4, 15.3, 13.6.
1
mg, 0.19 mmol, 89%). H NMR (300 MHz, CDCl3) d
1.21 (d, 6H, J=6.9 Hz), 1.27 (t, 3H, J=7.2 Hz), 2.22(s,
6H), 3.19 (s, 3H), 3.40 (heptet, 1H, J=6.9 Hz), 3.96 (s,
2H), 4.26 (q, 2H, J=7.2 Hz), 4.49 (s, 2H), 4.74 (s, 2H),
6.61 (s, 2H), 6.72 (s, 1H), 6.95 (s, 1H), 7.54 (d, 2H,
J=8.0 Hz), 8.08 (d, 2H, J=8.0 Hz); 13C NMR
(300 MHz, CDCl3) d 172.0, 171.0, 159.3, 156.2, 141.8,
138.5, 136.7, 135.5, 135.3, 130.6, 129.5, 127.3, 126.1,
122.4, 112.3, 101.3, 75.6, 59.5, 50.2, 28.9, 24.7, 22.4,
15.3, 13.6.
5-Isopropyl-6-methoxymethoxy-30-nitro-biphenyl-3-ylme-
thyl)-3,5-dimethyl-phenoxy]-acetic acid ethyl ester (5c).
To cesium carbonate (334.0 mg, 1.02 mmol) and 4c (90
mg, 0.20 mmol) in 5 mL of DMF was added ethyl-
bromoacetate (0.023 mL, 0.20 mmol). The reaction
mixture was stirredfor 30 min at room temperature,
pouredinto 15 mL of cold1 N HCl, andextractedwith
ethyl acetate (3ꢂ10 mL). The combinedorganic por-
tions were dried (MgSO4) andevaporatedto yield100
mg of crude, which was purified using flash column
chromatography (silica gel, 90:10 hexane/ethyl acetate)
to yield 5c (93.0 mg, 0.18 mmol, 85%). 1H NMR
(300 MHz, CDCl3) d 1.20 (d, 6H, J=6.9 Hz), 1.29 (t,
3H, J=7.2 Hz), 2.23 (s, 6H), 3.16 (s, 3H), 3.38 (heptet,
1H, J=6.9 Hz), 3.98 (s, 2H), 4.27 (q, 2H, J=7.2 Hz),
4.49 (s, 2H), 4.53 (s, 2H), 6.62 (s, 2H), 6.73 (s, 1H), 6.98
(s, 1H), 7.54 (t, 1H, J=8.0 Hz), 7.78 (d, 1H, J=7.6 Hz),
8.14 (d, 1H, J=8.0) 8.36 (s, 1H); 13C NMR (300 MHz,
CDCl3) d 159.3, 156.2, 148.9, 138.5, 137.5, 136.7, 135.5,
135.3, 133.5, 129.9, 126.1, 125.5, 122.5, 122.4, 112.3,
101.3, 75.6, 59.5, 50.2, 28.9, 24.7, 22.4, 15.3, 13.6.
[4-(40-Carbamoyl-5-isopropyl-6-methoxymethoxy-biphe-
nyl-3-ylmethyl)-3,5-dimethyl-phenoxy]-acetic acid ethyl
ester (5f). To cesium carbonate (335.6 mg, 1.03 mmol)
and 4f (90 mg, 0.21 mmol) in 5 mL of DMF was added
ethylbromoacetate (0.024 mL, 0.21 mmol). The reaction
mixture was stirredfor 30 min at room temperature,
pouredinto 15 mL of cold1 N HCl, andextractedwith
ethyl acetate (3ꢂ10 mL). The combinedorganic por-
tions were dried (MgSO4) andevaporatedto yield110
mg of crude, which was purified using flash column
chromatography (silica gel, 90:10 hexane/ethyl acetate)
to yield 5f (95.0 mg, 0.19 mmol, 90%). 1H NMR
(300 MHz, CDCl3) d 1.21 (d, 6H, J=6.9 Hz), 1.28 (t,
3H, J=7.2 Hz), 2.22 (s, 6H), 3.19 (s, 3H), 3.40 (heptet,
1H, J=6.9 Hz), 3.97 (s, 2H), 4.25 (q, 2H, J=7.2 Hz),
4.49 (s, 2H), 4.74 (s, 2H), 6.61 (s, 2H), 6.71 (s, 1H), 6.95
(s, 1H), 7.55 (d, 2H, J=8.4 Hz), 7.82 (d, 2H, J=8.4
Hz); 13C NMR (300MHz, CDCl3) d 169.7, 171.0, 159.3,
156.2, 140.8, 138.5, 136.7, 135.5, 135.3, 132.6, 127.8, 127.5,
126.1, 122.4, 112.3, 101.3,75.6, 59.5 50.2, 28.9, 24.7, 22.4,
15.3, 13.6.
5-Isopropyl-6-methoxymethoxy-20-nitro-biphenyl-3-ylme-
thyl)-3,5-dimethyl-phenoxy]-acetic acid ethyl ester (5d).
To cesium carbonate (334.0 mg, 1.02 mmol) and 4d (90
mg, 0.20 mmol) in 5 mL of DMF was added ethyl-
bromoacetate (0.023 mL, 0.20 mmol). The reaction
[4-(6-Hydroxy-5-isopropyl-biphenyl-3-ylmethyl)-3,5-di-
methyl-phenoxy]-acetic acid (GC-13). To the ester 5a

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
343
(72.0 mg, 0.15 mmol) in 4 mL of a 50% (v/v) mixture of
i-PrOH and THF was added 0.2 mL of 1 N HCl. The
reaction mixture was stirredfor 2 h at rt, dilutedwith 5
mL of water andextractedwith ethyl acetate (2 ꢂ25
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield60 mg of the corre-
sponding O-methoxymethyl deprotected phenol,
which was useddirectly in the following step. To the
above phenol (5 0.0 mg, 0.11 mmol) in 4 mL of
methanol was added 2.6 mL of 1 N NaOH. The
reaction mixture was stirredfor 1 h at rt, acidifiedwith
3 mL of 2 N HCl, andextractedwith ethyl acetate
(2ꢂ25 mL). The combinedorganic portions were dried
(MgSO4) andevaporatedto give GC-13 (40.0 mg, 0.099
organic portions were dried (MgSO4) andevaporatedto
give GC-19 (36.0 mg, 0.082 mmol, 80%). 1H NMR
(300 MHz, CDCl3) d 1.23 (d, 6H, J=6.9 Hz), 2.25 (s,
6H), 3.18 (heptet, 1H, J=6.9 Hz), 3.96 (s, 2H), 4.65 (s,
2H), 6.62 (s, 1H), 6.65 (s, 2H), 6.95 (s, 1H), 7.59 (t, 1H,
J=8.0 Hz), 7.74 (d, 1H, J=7.6 Hz), 8.19 (d, 1H,
J=8.0), 8.29 (s, 1H); 13C NMR (300 MHz, CDCl3) d
159.3, 151.5, 148.9, 138.5, 137.5, 136.9, 136.7, 135.8,
133.5, 129.9, 126.5, 125.9, 122.5, 122.4, 112.3, 77.8, 28.9,
24.7, 22.1, 15.3. HR-MS calcdfor
449.1838. Found: 449.1848.
C 26H27NO6:
[4-(6-Hydroxy-5-isopropyl-20-nitro-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenoxy]-acetic acid (GC-20). To the ester
5d (75 mg, 0.14 mmol) in 4 mL of a 50% (v/v) mixture
of i-PrOH and THF was added 0.2 mL of 1 N HCl. The
reaction mixture was stirredfor 2 h at rt, dilutedwith 5
mL of water andextractedwith ethyl acetate (2 25 mL).
1
mmol, 78%). H NMR (300 MHz, CD3OD) d 1.18 (d,
6H, J=6.9 Hz), 2.22 (s, 6H), 3.32 (heptet, 1H, J=6.9
Hz), 3.92 (s, 2H), 4.37 (s, 2H), 6.57 (s, 1H), 6.65(s, 2H),
6.87 (s, 1H), 7.28 (m, 1H), 7.35 (m, 2H), 7.42 (d,
2H); 13C NMR (300 MHz, CD3OD)
d
159.3.6,
The combinedorganic portions were rdied(MgSO
andevaporatedto yield62 mg of the corresponding
)
4
O-
151.5, 138.5, 136.7, 136.6, 135.8, 136.9, 129.0, 127.4,
126.1, 125.5, 122.4, 112.3, 77.8, 28.9, 24.7, 22.1,
15.3. HR-MS calcdfor C 26H28O4: 404.1988. Found:
404.2000.
methoxymethyl deprotected phenol, which was used
directly in the following step. To the above phenol (5 2.0
mg, 0.104 mmol) in 4 mL of methanol was added 2.6
mL of 1 N NaOH. The reaction mixture was stirredfor
1 h at rt, acidified with 3 mL of 2 N HCl, and extracted
with ethyl acetate (2ꢂ25 mL). The combinedorganic
portions were dried (MgSO4) andevaporatedto give
GC-20 (34.0 mg, 0.077 mmol, 75%). 1H NMR
(300 MHz, CDCl3) d 1.19 (d, 6H, J=6.9 Hz), 2.23 (s,
6H), 3.11 (heptet, 1H, J=6.9 Hz), 3.94 (s, 2H), 4.65 (s,
2H), 6.49 (s, 1H), 6.63 (s, 2H), 6.95 (s, 1H), 7.36 (d, 1H,
J=7.6 Hz), 7.48 (m, 1H), 7.60 (m, 1H), 7.91 (d, 1H,
J=8.0); 13C NMR (300 MHz, CDCl3) d 159.3, 151.5,
147.3, 138.5, 136.9, 136.7, 135.8, 135.1, 131.7, 128.3,
126.5, 125.9, 124.0, 124.1, 112.3, 77.8, 28.9, 24.7, 22.1,
15.3. HR-MS calcdfor C 26H27NO6: 449.1838. Found:
449.1839.
[4-(6-Hydroxy-5-isopropyl-40-nitro-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenoxy]-acetic acid (GC-14). To the ester
5b (75.0 mg, 0.14 mmol) in 4 mL of a 50% (v/v) mixture
of i-PrOH andTHF was added0.2 mL of 1 N HCl. The
reaction mixture was stirredfor 2 h at rt, dilutedwith 5
mL of water andextractedwith ethyl acetate (2 25 mL).
The combinedorganic portions were rdied(MgSO
andevaporatedto yield65 mg of the corresponding
)
O-
4
methoxymethyl deprotected phenol, which was used
directly in the following step. To the above phenol (5 0.0
mg, 0.10 mmol) in 4 mL of methanol was added 2.6 mL
of 1 N NaOH. The reaction mixture was stirredfor 1 h
at rt, acidified with 3 mL of 2 N HCl, and extracted with
ethyl acetate (2ꢂ25 mL). The combinedorganic por-
tions were dried (MgSO4) andevaporatedto give GC-14
(33.0 mg, 0.075 mmol, 75%). 1H NMR (300 MHz,
CD3OD) d 1.19 (d, 6H, J=6.9 Hz), 2.21 (s, 6H), 3.31
(heptet, 1H, J=6.9 Hz), 3.94 (s, 2H), 4.36 (s, 2H), 6.63
(s, 1H), 6.65 (s, 2H), 6.95 (s, 1H), 7.62 (d, 2H, J=8.7
Hz), 8.21 (d, 2H, J=8.7 Hz); 13C NMR (300 MHz,
CD3OD) d 159.3, 151.5, 147.3, 142.7, 138.5, 136.9,
136.7, 135.8, 128.3, 126.5, 125.9, 124.1, 124.0, 112.3,
77.8, 28.9, 24.7, 22.1, 15.3. HR-MS calcdfor
C26H27NO6: 449.1838. Found: 449.1844.
50-(4-Carboxymethoxy-2,6-dimethyl-benzyl)-20-hydroxy-
30-isopropyl-biphenyl-4-carboxylic acid (GC-21). To the
ester 5e (83.0 mg, 0.16 mmol) in 5 mL of a 50% (v/v)
mixture of i-PrOH andTHF was added0.3 mL of 1 N
HCl. The reaction mixture was stirredfor 2 h at rt,
diluted with 7 mL of water and extracted with ethyl
acetate (3ꢂ25 mL). The combinedorganic portions
were dried (MgSO4) andevaporatedto yield70 mg of
the corresponding O-methoxymethyl deprotected phe-
nol, which was useddirectly in the following step. To
the above phenol (65.0 mg, 0.14 mmol) in 4 mL of
methanol was added 2.6 mL of 1 N NaOH. The reaction
mixture was stirredfor 1 h at rt, acidifiedwith 3 mL of
2 N HCl, andextractedwith ethyl acetate (2 ꢂ25 mL).
[4-(6-Hydroxy-5-isopropyl-30-nitro-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenoxy]-acetic acid (GC-19). To the ester
5c (75 mg, 0.14 mmol) in 4 mL of a 50% (v/v) mixture
of i-PrOH andTHF was added0.2 mL of 1 N HCl. The
reaction mixture was stirredfor 2 h at rt, dilutedwith 5
mL of water andextractedwith ethyl acetate (2 ꢂ25
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield60 mg of the corre-
sponding O-methoxymethyl deprotected phenol, which
was useddirectly in the following step. To the above
phenol (5 0.0 mg, 0.10 mmol) in 4 mL of methanol was
added 2.6 mL of 1 N NaOH. The reaction mixture was
stirredfor 1 h at rt, acidifiedwith 3 mL of 2 N HCl, and
extractedwith ethyl acetate (2 25 mL). The combined
The combinedorganic portions were rdied(MgSO
)
4
andevaporatedto give GC-21 (51.0 mg, 0.11 mmol,
75%). 1H NMR (300 MHz, CDCl3) d 1.21 (d, 6H,
J=6.9 Hz), 2.23 (s, 6H), 3.20 (heptet, 1H, J=6.9 Hz),
3.96 (s, 2H), 4.69 (s, 2H), 6.63 (s, 1H), 6.76 (s, 2H), 6.99
(s, 1H), 7.53 (d, 2H, J=8.0 Hz), 8.18 (d, 2H, J=8.0
Hz); 13C NMR (300 MHz, CDCl3) d 176.0, 172.0, 159.3,
151.5, 141.8, 138.5, 136.9, 136.7, 135.8, 130.6, 129.5,
127.3, 126.5, 124.0, 112.3, 77.8, 28.9, 24.7, 22.1, 15.3.
HR-MS calcdfor
448.1889.
C
27H28O6: 448.1885. Found:

344
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
[4-(40-Carbamoyl-6-hydroxy-5-isopropyl-biphenyl-3-ylme-
thyl)-3,5-dimethyl-phenoxy]-acetic acid (GC-22). To the
ester 5f (80.0 mg, 0.14 mmol) in 4 mL of a 50% (v/v)
mixture of i-PrOH and THF was added 0.2 mL of 1 N
HCl. The reaction mixture was stirredfor 2 h at rt,
diluted with 5 mL of water and extracted with ethyl
acetate (2ꢂ25 mL). The combinedorganic portions
were dried (MgSO4) andevaporatedto yield65 mg of
the corresponding O-methoxymethyl deprotected phe-
nol, which was useddirectly in the following step. To
the above phenol (53.0 mg, 0.10 mmol) in 4 mL of
methanol was added 2.6 mL of 1 N NaOH. The reaction
mixture was stirredfor 1 h at rt, acidifiedwith 3 mL of
2 N HCl, andextractedwith ethyl acetate (2 ꢂ25 mL).
mixture was stirredfor 30 min at rt, pouredinto 15 mL
of cold1 N HCl, andextractedwith ethyl acetate (3 ꢂ10
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield50 mg of crued,
which was purifiedusing flash column chromato-
graphy (silica gel, 90:20 hexane/ethyl acetate) to
yield 7 ( 45 mg, 0.075 mmol 80%). 1H NMR
(300 MHz, CDCl3) d 1.17 (d, 6H, J=6.9 Hz), 1.41 (s,
9H), 1.48 (s, 9H), 2.22 (s, 6H), 3.38 (s, 3H), 3.57 (heptet,
1H, J=6.9 Hz), 3.86 (s, 2H), 3.93 (s, 2H), 4.49 (s, 2H),
4.54 (s, 2H), 6.60 (s, 2H), 6.66 (d, 2H, J=8.7 Hz), 6.70
(s, 1H), 6.85 (s, 1H), 7.30 (d, 2H, J=8.7 Hz); 13C NMR
(300 MHz, CDCl3) d 159.3, 156.2, 142.4, 138.5, 136.7,
135.5, 135.3, 128.2, 126.1, 125.5, 125.0, 122.4, 112.8,
112.3, 101.3, 76.2, 73.2, 72.9, 55.5, 50.2, 28.9, 29.0, 24.7,
22.4, 15.3.
The combinedorganic portions were rdied(MgSO
)
4
andevaporatedto give GC-22 (34.0 mg, 0.075 mmol,
75%). 1H NMR (300 MHz, CDCl3) d 1.21 (d, 6H,
J=6.9 Hz), 2.23 (s, 6H), 3.25 (heptet, 1H, J=6.9 Hz),
3.94 (s, 2H), 4.35 (s, 2H), 6.60 (s, 1H), 6.65 (s, 2H), 6.90
(s, 1H), 7.49 (d, 2H, J=8.4 Hz), 7.88 (d, 2H, J=8.0
Hz); 13C NMR (300 MHz, CDCl3) d 176.0, 169.7, 159.3,
151.5, 140.0, 138.5, 136.9, 136.7, 135.8, 132.6, 127.8,
127.5, 126.5, 124.0, 112.3, 77.8, 28.9, 24.7, 22.1, 15.3.
{4-[40-(Carboxymethyl-amino)-6-hydroxy-5-isopropyl-bi-
phenyl-3-ylmethyl]-3,5-dimethyl-phenoxy}-acetic
acid
(GC-15). To the ester 7 (40 mg, 0.06 mmol) in 2 mL of
a 50% (v/v) mixture of i-PrOH and THF was added 0.2
mL of 1 N HCl. The reaction mixture was stirredfor 2 h
at rt, diluted with 3 mL of water and extracted with
ethyl acetate (2ꢂ15 mL). The combinedorganic por-
tions were dried (MgSO4) andevaporatedto yield30
mg of the corresponding O-methoxymethyl deprotected
phenol, which was useddirectly in the following step.
To the above phenol (25 mg, 0.04 mmol ) in 2 mL of
methanol was added 1.3 mL of 1 N NaOH. The reaction
mixture was stirredfor 1 h at rt, acidifiedwith 1.5 mL of
2 N HCl, andextractedwith ethyl acetate (2 ꢂ25 mL).
HR-MS calcdfor
447.2037.
C 27H29NO5: 447.2025. Found:
50-[2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl]-30-iso-
propyl-20-methoxymethoxy-biphenyl-4-ylamine (6). To a
50 mL round-bottomed flask equipped with stirrer and
reflux condenser was added: compound 3b (150 mg,
0.25 mmol), iron power (49 mg, 0.87 mmol), glacial
acetic acid(0.104 mL, 1.74 mmol), andabsolute ethanol
(3 mL). The mixture was stirredandrefluxedfor 2 h
under argon and was then added to water (25 mL). The
water layer was extractedwith chloroform (4 ꢂ25 mL).
The combinedorganic portions were washedwith brine,
dried (MgSO4), filtered, and concentrated in vacuo to
The combinedorganic portions were rdied(MgSO
)
4
andevaporatedto give GC-15 (15 mg. 0.03 mmol,
75%). 1H NMR (300 MHz, CDCl3) d 1.17 (d, 6H,
J=6.9 Hz), 2.22 (s, 6H), 3.44 (heptet, 1H, J=6.9 Hz),
3.92 (s, 2H), 3.98 (s, 2H), 4.60 (s, 2H), 6.65 (s, 2H), 6.68
(s, 1H), 6.84 (d, 2H, J=8.4 Hz), 6.90 (s, 1H), 7.31 (d,
2H, J=8.4 Hz); 13C NMR (300 MHz, CDCl3) d 159.3,
151.5, 142.4, 138.5, 136.9, 136.7, 135.8, 128.2, 126.5,
125.9, 125.0, 124.0, 112.8, 112.3, 77.8, 57.1, 28.9, 24.7,
22.1, 15.3. HR-MS calcdfor C 28H31NO6: 477.2151.
Found: 477.2142.
1
give 6 (112 mg, 0.20 mmol, 80%). H NMR (300 MHz,
CDCl3) d 1.1 (d, 18 H, J=6.9 Hz), 1.19 (d, 6H, J=6.9
Hz), 1.25 (m, 3H), 2.19 (s, 6H), 3.17 (s, 3H), 3.35 (hep-
tet, 1H, J=6.9 Hz), 3.90 (s, 2H), 4.53 (s, 2H), 6.58 (s,
2H), 6.61 (s, 1H), 6.74 (d, 2H, J=8.4 Hz), 6.81 (s, 1H),
7.15 (d, 2H, J=8.4 Hz); 13C NMR (300 MHz, CDCl3) d
153.9, 149.5, 145.2, 142.0, 138.1, 137.9, 136.3, 134.5,
130.3, 129.9, 129.7, 127.5, 124.3, 119.4, 114.9, 99.2, 76.4,
57.3, 33.9, 26.4, 23.7, 20.4, 18.0, 12.7.
1-{50-[2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl]-30-
isopropyl-20 -methoxymethoxy-biphenyl-4-yl}-3-phenyl-
urea (8). To the amine 6 (60 mg, 0.105 mmol) andpyri-
dine (2.65 mg, 0.03 mmol) in 2 mL of DMF was added
phenyl isocianate (14.5 mg, 0.105 mmol). The reaction
mixture was stirredfor 3 h at rt, pouredinto 5 mL of
water, andextractedwith ether (3 ꢂ10 mL). The com-
binedorganic portions were washedwith brine (20 mL),
dried (MgSO4), andevaporatedto yield70 mg of crude,
which was purifiedusing flash column chromatography
(silica gel, 90:20 hexane/ethyl acetate) to yield 8 (55 mg,
50-(4-tert-Butoxycarbonylmethoxy-2,6-dimethyl-benzyl)-
30-isopropyl-20-methoxymethoxy-biphenyl-4-ylamino]-ace-
tic acid tert-butyl ester (7). Compound 6 (85 mg, 0.15
mmol) andBu 4NF (0.190 mL, 1.0 M in THF) were
combinedin a roundbottom flask. Deprotection was
determined to be nearly instantaneous by TLC. The
reaction mixture was diluted with ethyl acetate (25
mL) andwashedwith water (2 ꢂ25 mL) andbrine
(30 mL), dried, and concentrated. The crude product
was purifiedby flash column chromatography (80:20
hexane/ethyl acetate) to yield52 mg, (0.12 mmol, 80%)
of 4-(40-Amino-5-isopropyl-6-methoxymethoxy-biphenyl-3
- ylmethyl)-3,5-dimethyl-phenol. To the above phenol
(40 mg, 0.092 mmol ) andcesium carbonate (150 mg,
0.46 mmol) in 3 mL of DMF was added tert-butyl-
chloroacetate (27.86 mg, 0.185 mmol). The reaction
1
0.079 mmol, 75%). H NMR (300 MHz, CDCl3) d 1.10
(d, 18 H, J=6.9 Hz), 1.17 (d, 6H, J=6.9 Hz), 1.25 (m,
3H), 2.18 (s, 6H), 3.26 (s, 3H), 3.37 (heptet, 1H, J=6.9
Hz), 3.94 (s, 2H), 4.51 (s, 2H), 6.6 (s, 2H), 6.74 (s, 1H),
6.8 (s, 1H), 7.00 (m, 1H), 7.3–7.5 (m, 8H); 13C NMR
(300 MHz, CDCl3) d 156.2, 152.6, 152.2, 138.4, 138.2,
137.3, 137.1, 135.5, 135.3, 128.7, 127.6, 126.1, 125.5,
124.1, 122.4, 120.9, 120.4, 118.3, 101.3, 50.2, 28.9, 24.7,
22.4, 15.3, 14.8, 2.2.

G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
345
{4-[6-Hydroxy-5-isopropyl-40-(3-phenyl-ureido)-biphenyl-
3-ylmethyl]-3,5-dimethyl-phenoxy}-acetic acid (GC-16).
The above N,N-diphenylurea analogue 8 (50 mg, 0.072
mmol) was converted by the procedure described in the
synthesis of GC-14, starting from compound 3b, to give
GC-16 (24 mg, 0.045 mmol, 63%). 1H NMR (300 MHz,
CDCl3) d 1.18 (d, 6H, J=6.9 Hz), 2.21 (s, 6H), 3.30
(heptet, 1H, J=6.9 Hz), 3.92 (s, 2H), 4.36 (s, 2H), 6.56
(s, 1H), 6.65 (s, 2H), 6.85 (s, 1H), 7.01 (m, 1H), 7.27–
7.32 (m, 4H), 7.41–7.44 (m, 4H); 13C NMR (300 MHz,
CDCl3) d 159.3, 152.2, 151.5, 138.5, 138.2, 137.1, 136.7,
136.9, 135.8, 128.7, 127.6, 126.5, 125.5, 124.0, 124.1,
120.9, 120.4, 112.3, 77.8, 28.9, 24.7, 22.1, 15.3. HR-MS
calcdfor C 33H34N2O5: 538.2468. Found: 538.2488.
CDCl3) d 1.18 (d, 6H, J=6.9 Hz), 1.27 (t, 3H, J=6.8
Hz), 2.23 (s, 6H), 3.28 (s, 3H), 3.40 (heptet, 1H, J=6.9
Hz), 3.94 (s, 2H), 4.25 (q, 2H, J=6.8 Hz), 4.52 (s, 2H),
4.59 (s, 2H), 6.55 (s, 1H), 6.62 (s, 2H), 6.70 (d, 2H, J=8.4
Hz), 6.85 (s, 1H), 7.21 (d, 2H, J=8.4 Hz); 13C NMR
(300 MHz, CDCl3) d 159.3, 156.2, 145.6, 138.5, 136.7,
135.5, 135.3, 128.2, 126.6, 126.1, 125.5, 122.4, 115.6,
112.3, 101.3, 75.6, 59.5, 50.2, 28.9, 24.7, 22.4, 15.3.
[4-(40-Amino-6-hydroxy-5-isopropyl-biphenyl-3-ylmethyl)-
3,5-dimethyl-phenoxy]-acetic acid (GC-18). To the ester
10 (50 mg, 0.1 mmol) in 4 mL of a 50% (v/v) mixture of
i-PrOH and THF was added 0.2 mL of 1 N HCl. The
reaction mixture was stirredfor 2 h at rt, dilutedwith 5
mL of water andextractedwith ethyl acetate (2 ꢂ25
mL). The combinedorganic portions were rdied
(MgSO4) andevaporatedto yield45 mg of the corre-
sponding O-methoxymethyl deprotected phenol, which
was useddirectely in the following step. To the above
phenol (40 mg, 0.09 mmol) in 4 mL of methanol was
added 2.6 mL of 1 N NaOH. The reaction mixture was
stirredfor 1 h at rt, acidifiedwith 3 mL of 2 N HCl, and
extractedwith ethyl acetate (2 ꢂ25 mL). The combined
organic portions were dried (MgSO4) andevaporatedto
give GC-18 (31.0 mg, 0.072 mmol,72%). 1H NMR
(300 MHz, CDCl3) d 1.18 (d, 6H, J=6.9 Hz), 2.23 (s,
6H), 3.40 (heptet, 1H, J=6.9 Hz), 3.94 (s, 2H), 4.52 (s,
2H), 6.55 (s, 1H), 6.62 (s, 2H), 6.70 (d, 2H, J=8.4 Hz),
6.85 (s, 1H), 7.21 (d, 2H, J=8.4 Hz); 13C NMR
(300 MHz, CDCl3) d 159.3, 151.5, 145.6, 138.5, 136.9,
136.7, 135.8, 128.2, 126.6, 126.3, 125.9, 124.0, 115.6,
112.3, 77.8, 28.9, 24.7, 22.1, 15.3. HR-MS calcdfor
C26H29NO4: 419.2132. Found: 419.2146.
But-2-ynyl-{50 -[2,6-dimethyl-4-(trisopropyl-silanyloxy)-
benzyl]-30-isopropyl-20-methoxymethoxy-biphenyl-4-yl}-
amine (9). To the amine 6 (70 mg, 0.12 mmol) and
cesium carbonate (mg, 0.3 mmol) in 3 mL of DMF was
added 1-bromo-2-butyne (0.013 mL, 0.15 mmol). The
reaction mixture was stirredfor 1 h at rt, pouredinto 10
mL of cold1 N HCl, andextractedwith ethyl acetate
(3ꢂ10 mL). The combinedorganic portions were dried
(MgSO4) andevaporatedto yield80 mg of crude, which
was purifiedusing flash column chromatography (silica
gel, 2:1 hexane/ethyl acetate) to yield 9 (55 mg, 0.09
1
mmol, 75%). H NMR (300 MHz, CDCl3) d 1.12 (d,
18H, J=6.9 Hz), 1.18 (d, 6H, J=6.9 Hz), 1.25 (m, 3H),
1.81 (s, 3H), 2.18 (s, 6H), 3.27 (s, 3H), 3.42 (heptet, 1H,
J=6.9 Hz), 3. 88 (s, 2H), 3.93 (s, 2H), 4.53 (s, 2H), 6.65
(d, 2H, J=4.8 Hz), 6.74 (s, 1H), 6.81 (s, 1H), 7.30 (d,
2H, J=4.8 Hz); 13C NMR (300 MHz, CDCl3) d 156.2,
152.6, 142.4, 138.4, 137.3, 135.5, 135.3, 128.2, 126.1,
125.5, 125.0, 122.4, 118.3, 112.8, 101.3, 76.8, 50.2, 38.8,
28.9, 24.7, 22.4, 15.3, 14.8, 2.2, 1.2.
N-{50 -[2,6-Dimethyl-4-(triisopropyl-silanyloxy)-benzyl]-
30-isopropyl-20-methoxy methoxy-biphenyl-4-yl}-N-(2,2,
5,7,8-pentamethyl-chroman-6-yl)-guanidine (11). Com-
pound 6 (260 mg, 0.46 mmol) andPmc- S-methyl-
isothiourea (214 mg, 0.60 mmol) were dissolved in
anhydrous THF (20 mL). TEA (0.13 mL, 0.93 mmol)
andHg(ClO 4)2 (200 mg, 0.51 mmol) were added and the
mixture was refluxedovernight. An additional 100 mg (0.7
equiv) of Pmc-S-methylisothiourea was added and
refluxing continuedfor another 4 h. The mixture was
concentrated in vacuo and the remaining residue was dis-
solvedin ethyl acetate (75 mL), filteredthrough Celite,
which was washedwith ethyl acetate (3 ꢂ50 mL). The
[4-(40-But-2-ynylamino-6-hydroxy-5-isopropyl-biphenyl-
3-ylmethyl)-3,5-dimethyl-phenoxy]-acetic acid (GC-17).
The above amine (50 mg, 0.08 mmol) was convertedby
the procedure described in the synthesis of GC-14,
starting from compound 3b, to give GC-17 (25 mg, 0.05
mmol, 65%).1H NMR (300 MHz, CDCl3) d 1.20 (d, 6H,
J=6.9 Hz), 1.81 (s, 3H), 2.24 (s, 6H), 3.27 (heptet, 1H,
J=6.9 Hz), 3. 89 (s, 2H), 3.92 (s, 2H), 4.63 (s, 2H), 6.55
(s, 1H), 6.62 (s, 2H), 6.72 (d, 2H, J=4.8 Hz), 6.87 (s,
1H), 7.20 (d, 2H, J=4.8 Hz); 13C NMR (300 MHz,
CDCl3) d 159.3, 151.5, 142.4, 138.5, 136.9, 136.7, 135.8,
128.2, 126.5, 125.9, 125.0, 124.0, 112.8, 112.3, 77.8, 76.8,
38.8, 28.9, 24.7, 22.1, 15.3, 1.2. HR-MS calcdfor
C30H33NO4: 471.2410. Found: 471.2421.
combinedfiltrate was washedwith H 2O, satdNaHCO ,
3
andbrine, driedwith MgSO 4, filtered, and concentrated in
vacuo to yielda yellow foam. The foam was chromato-
graphedon silica gel (3:1 to 2:1 gradient hexane/ethyl
acetate) to yield the desired product (206 mg, 51%) as a
yellow solid. 1H NMR (400 MHz, CDCl3) d 1.1 (d, 18H,
J=6.9 Hz), 1.21 (d, 6H, J=6.9 Hz), 1.25 (m, 3H), 1.31 (s,
6H), 1.82 (t, 2H, J=6.8 Hz), 2.13 (s, 3H), 2.18 (s, 6H), 2.62
(s, 3H), 2.64 (s, 3H), 2.65 (t, 2H, J=6.8 Hz), 3.23 (s, 3H),
3.39 (heptet, 1H, J=6.9 Hz), 3.95 (s, 2H), 4.51 (s, 2H),
6.60 (s, 2H), 6.65 (s, 1H), 6.94 (s, 1H), 7.21 (d, 2H, J=8.4
Hz), 7.51 (d, 2H, J=8.4 Hz); 13C NMR (400MHz,
CDCl3) d 154.4, 153.9, 149.6, 142.4, 138.7, 138.0, 136.5,
135.7, 135.2, 134.1, 133.4, 132.8, 130.9, 129.4, 127.3,
125.7, 124.8, 124.2, 119.5, 118.0, 99.56, 73.7, 57.2, 33.9,
32.8, 26.7, 26.4, 23.7, 21.4, 20.4, 18.5, 17.9, 17.4, 12.6, 12.1.
[4-(40-Amino-5-isopropyl-6-methxymethoxy-biphenyl-3-yl-
methyl)-3,5-dimethyl-phenoxy]-acetic acid ethyl ester
(10). To a 50 mL round-bottomed flask equipped with
stirrer and reflux condenser was added: compound 5b
(75 mg, 0.14 mmol), iron power (27.4 mg, 0.49 mmol),
glacial acetic acid(1.0 mmol), and5 mL of absolute
ethanol. The mixture was stirredandrefluxedfor 2 h
under argon and was then added to water (25 mL). The
water layer was extractedwith chloroform (4 ꢂ25 mL).
The combinedorganic portions were washedwith brine,
dried (MgSO4), filtered, and concentrated in vacuo to
1
give 10 (55 mg, 0.11 mmol, 78%). H NMR (300 MHz,

346
G. Chiellini et al. / Bioorg. Med. Chem. 10 (2002) 333–346
(4-{5-Isopropyl-6-methoxymethoxy-40-[N-(2,2,5,7,8-pen-
tamethyl-chroman-6-yl)-guanidino]-biphenyl-3-ylmethyl}-
3,5-dimethyl-phenoxy)-acetic acid tert-butyl ester (12).
References and Notes
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Compound 11 (195 mg, 0.22 mmol) andBu NF (0.28
4
mL, 1.0 M in THF) were combinedin a roundbottom
flask. The reaction was allowedto stir at rt for 10 min.
It was then diluted with ether (25 mL) and washed with
water (2ꢂ25 mL) andbrine (30 mL), driedover MgSO
,
4
andconcentratedto yieldorange foam. The crude pro-
duct was purified by flash column chromatography (2:1
hexane/ethyl acetate) to yield153 mg (96%) of the
desired phenol product, which was used directly in the
following step. To the above phenol (145.0 mg, 0.20
mmol) andcesium carbonate (335.0 mg,1.00 mmol) in 5
mL DMF, was added tert-butylchloroacetate (0.036
mL, 0.25 mmol). The reaction mixture was stirredfor 30
min at rt, pouredinto 10 mL of cold1 N HCl, and
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column chromatography (silica gel, 4:1 hexane/ethyl
acetate) to yield 12 (50.0 mg, 0.06 mmol, 30%). 1H
NMR (400 MHz, CDCl3) d 1.19 (d, 6H, J=6.9 Hz),
1.31 (s, 6H), 1.48 (s, 9H), 1.81 (t, 2H, J=6.8 Hz), 2.12
(s, 3H), 2.21 (s, 6H), 2.60 (s, 3H), 2.62 (s, 3H), 2.65 (t,
2H, J=6.8 Hz), 3.22 (s, 3H), 3.39 (heptet, 1H, J=6.9
Hz), 3.95 (s, 2H), 4.48 (s, 2H), 4.50 (s, 2H), 6.61 (s, 2H),
6.64 (s, 1H), 6.95 (s, 1H), 7.25 (d, 2H, J=8.4 Hz), 7.47
(d, 2H, J=8.4 Hz); 13C NMR (400 MHz, CDCl3) d
154.3, 153.9, 149.5, 142.3, 138.4, 137.6, 136.5, 135.7,
135.1, 134.8, 133.7, 132.7, 130.4, 128.7, 127.1, 125.7,
124.2, 123.7, 118.0, 114.9, 99.4, 75.6, 73.7, 59.5, 57.2,
33.9, 32.7, 26.7, 26.4, 23.7, 21.4, 20.3, 18.5, 17.5, 14.1,
13.6, 12.1.
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[4-(40-Guanidino-6-hydroxy-5-isopropyl-biphenyl-3-ylme-
thyl)-3,5-dimethyl-phenoxy]-acetic acid (GC-23). To the
ester 12 (32.0 mg, 0.04 mmol) dissolved in CH2Cl2 (3
mL) was added TFA (3 mL). The reaction was stirred at
rt for 1 h. The reaction mixture was then diluted with
ethyl acetate (25 mL) andwashedwith satdNaHCO
3
(5ꢂ15 mL), water, andbrine. The combinedorganic
portions were dried (MgSO4) andevaporate.d The
crude product was purified by preparative TLC (4:1:1
ethyl acetate/hexane/MeOH) to yieldthe desiredpro-
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6H), 2.60 (s, 3H), 3.22 (s, 3H), 3.33 (heptet, 1H, J=6.9
Hz), 3.93 (s, 2H), 4.40 (s, 2H), 6.44 (s, 1H), 6.62 (s, 2H),
7.01 (s, 1H), 7.22 (d, 2H, J=8.0 Hz), 7.44 (d, 2H, J=8.0
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Acknowledgements
This work was supportedby grants from the National
Institutes of Health (DK 52798, T.S.S.; DK 41842,
J.D.B.). J.D.B. has proprietary interests in, andserves
as a consultant and deputy director to Karo Bio AB,
which has commercial interests in this area of research.