Design, synthesis, and evaluation of novel 3,6-diaryl-4- aminoalkoxyquinolines as selective agonists of somatostatin receptor subtype 2

Article abstract of DOI:10.1021/jm101501b

Agonists of somatostatin receptor subtype 2 (sst₂) have been proposed as therapeutics for the treatment of proliferative diabetic retinopathy and exudative age-related macular degeneration. An HTS screen identified 2-quinolones as weak agonists of sst₂, and these were optimized to provide small molecules with sst₂ binding and functional potency comparable to peptide agonists. Agonist 21 was shown to inhibit rat growth hormone secretion following systemic administration and to inhibit ocular neovascular lesion formation after local administration.

Full text of DOI:10.1021/jm101501b

ARTICLE
pubs.acs.org/jmc
Design, Synthesis, and Evaluation of Novel 3,6-Diaryl-4-
aminoalkoxyquinolines as Selective Agonists of Somatostatin
Receptor Subtype 2
||
Scott E. Wolkenberg,*,† Zhijian Zhao,† Catherine Thut,‡, Jill W. Maxwell,‡ Terrence P. McDonald,‡
Fumi Kinose,‡ Michael Reilly,§,¥ Craig W. Lindsley,†,^ and George D. Hartman†
Departments of †Medicinal Chemistry, ‡Ophthalmics Research, and §Drug Metabolism, Merck Research Laboratories, Sumneytown
Pike, P.O. Box 4, West Point, Pennsylvania 19486, United States
S Supporting Information
b
ABSTRACT:
Agonists of somatostatin receptor subtype 2 (sst2) have been proposed as therapeutics for the treatment of proliferative diabetic
retinopathy and exudative age-related macular degeneration. An HTS screen identified 2-quinolones as weak agonists of sst2, and
these were optimized to provide small molecules with sst2 binding and functional potency comparable to peptide agonists. Agonist
21 was shown to inhibit rat growth hormone secretion following systemic administration and to inhibit ocular neovascular lesion
formation after local administration.
’ INTRODUCTION
equal potency for sst1, 2A, 2B, 3-5).9 Two such sst2/sst5 selective
cyclic peptides, octreotide and lanreotide, are currently used for
the management of acromegaly as well as carcinoid tumors and
VIPomas. Despite their improved PK and selectivity versus
somatostatin, both are delivered via intramuscular injection,
and the development of novel orally bioavailable sst2 agonists
is desirable.
In addition to their established role in the treatment of
acromegaly, sst2 agonists have been proposed as therapeutics for
the treatment of ocular angiogenic diseases such as proliferative
diabetic retinopathy (PDR) and exudative age-related macular
degeneration (wet AMD).10 The role of somatostatin in these
diseases is somewhat unclear, and its putative beneficial effects in
these diseases could be mediated directly, via sst2 expressed on
retinal endothelial cells,6 or indirectly via sst2-dependent modula-
tion of the GH-insulin-like growth factor 1 (IGF-1) axis.11 Initial
preclinical and clinical studies suggested that sst2 agonists might
inhibit and even regress PDR through its actions on GH
release.12,13 However, these initial findings have not been recapi-
tulated in Ph 3 clinical trials. Recently, sst2 expression on vascular
Somatostatin is a peptide hormone secreted by the hypotha-
lamus that signals through six receptor subtypes (sst1, 2A, 2B, 3-5
)
of the G protein-coupled receptor (GPCR) class.1,2 Somatostatin
has a wide variety of functions in the body, the most well-studied
of which are its inhibitory actions on hormones of the pituitary/
hypothalamic axis including thyroid stimulating hormone
(TSH), growth hormone releasing hormone (GHRH), ghrelin,
and growth hormone (GH). Recently, a variety of nonhormonal
activities have been attributed to somatostatin as well, including
roles in inflammation,3,4 cell proliferation,5 angiogenesis,6,7 and
neurotransmission.1
Somatostatin receptor subtype 2 (sst2) mediates the inhibitory
effects of somatostatin on GH, adrenocorticotropin, glucagon,
vasoactive intestinal peptide, and gastric acid secretion. These
actions have led a number of groups to seek to develop sst2
selective agonists for the treatment of a variety of neuroendocrine
tumors that result in acromegaly and diarrheas associated with
carcinoid tumors and endocrine tumors producing vasoactive
intestinal peptides (VIPomas). Early sst2 agonists were peptide-
based somatostatin analogues with improved plasma half-life
(t1/2 of several hours), potency, and selectivity (primarily sst2 and
sst5)8 versus endogenous somatostatin (plasma t1/2 = 1-3 min,
Received: November 22, 2010
Published: March 11, 2011
r
2011 American Chemical Society
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Journal of Medicinal Chemistry
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endothelial cells has been demonstrated, as has the ability of sst2
agonists to inhibit endothelial cell proliferation, suggesting a
potential non-GH dependent antiangiogenic mechanism.6
Herein, we describe the discovery and in vivo characterization
of selective nonpeptide sst2 agonists. Consistent with the
reported effects of peptide sst2 agonists, the novel agents sup-
press GH secretion in rats. In addition, they decrease neovascular
lesions when administered locally to the eye in a rat choroidal
neovascularization model.
Scheme 1. Initial Synthesis of Quinoline Compounds 4 and 5
’ RESULTS AND DISCUSSION
A high throughput screen of the Merck screening collection
resulted in the identification of 1 as a modest affinity binder of
sst2 (Figure 1). The 3-aryl-4-aminoalkoxy-6-carboxamide series
was originally discovered as gonadotropin-releasing hormone
(GnRH) antagonists, and 1 exhibits potent GnRH activity.14-18
Two modifications of this structure eliminate GnRH activity and
dramatically increase affinity for sst2: removal of the C6 carbox-
amide and removal of the C2 carbonyl. These beneficial changes
were discovered serendipitously via sst2 screening of compounds
from this series prepared during the GnRH effort. Individually,
these changes boost sst2 binding potency by 1000- and 100-fold,
respectively (see 2 and 3) and when combined, as in 4, an
extremely potent sst2 ligand results. This ligand also displays
functional agonism, as 4 inhibits forskolin-stimulated cyclic
adenosine monophosphate (cAMP) release with an IC50 of 17
nM. In some cases, removal of the 7-chlorine is also tolerated (5)
without deleterious effect on binding or functional potency
(cAMP IC50 = 7.6 nM) or selectivity (>250-fold vs sst1, 3-5).
Despite these advances upon simplification of 1-5, further
optimization was required, especially with regard to physical and
pharmacokinetic properties. Compound 5 exhibits low aqueous
solubility (<0.03 μg/mL at pH 7.4) and poor pharmacokinetics
(e.g., dog Cl = 46 mL/min/kg), making it unsuitable for in vivo
study, and an iterative analogue library approach was employed
in its optimization.
Compounds 1-5 were prepared according to the route
shown in Scheme 1, a slight modification of the published route
used to synthesize GnRH inhibitors.14,15,18 The advanced qui-
nolone intermediate 6 was converted to biaryl 7 under Pd
catalysis before being converted to its corresponding triflate.
This intermediate could be converted to the 7-Cl and des-Cl
analogues via partial or exhaustive reduction prior to Boc
deprotection. This route efficiently provided the target com-
pounds; however, the quinoline 3- and 6-aryl groups cannot be
easily modified in parallel. To address this inefficiency, alternative
syntheses of 4-alkoxy-3,6-biarylquinolines were utilized to pre-
pare focused libraries of analogues.19 These libraries typically
contained 24-48 members and were prepared in an iterative
fashion, with in vitro binding and functional data informing
monomer selection in each round of synthesis.
Selected results for optimization of the 6-aryl group are
presented in Table 1. Because of the objective of improving
physical and pharmacokinetic properties, studies focused on
heteroaromatics and carbocyclic aromatics bearing polar substit-
uents. In terms of binding potency, both were well tolerated,
providing sst2 binders with affinity <1 nM. Five- and six-
membered heteroaromatics and phenyl rings bearing hydrogen
bond donating and accepting groups all provided very potent
binders, and so long as an aromatic group was present, no
significant steric or electronic effects were found. In contrast,
functional potency varied, and in most cases, significant cAMP
IC50/Ki shifts (10-100-fold) were observed. The structure-
activity relationship within the pyridine series at C6 (8-14)
indicates that hydroxyl substitution (i.e., replacement of pyridine
with pyridinone) is especially effective in reducing the shift
between functional and binding potency (compare 8 and 9).
The effect is not reproduced with analogous amino substitution
(compare 10 and 9) or the corresponding phenol (15). The
shifts observed could not be rationalized in terms of electronic
effects or H-bond donors/acceptors, but a relationship between
logD and functional/binding shifts was observed. Plotting the
Figure 1. Screening lead and initial optimization.
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Table 1. sst2 Binding Affinities and Functional Potency for
Test Compoundsa
Figure 2. cAMP IC50/Ki ratio as a function of ClogD.
logD, certain C6 aryl substituents increased binding potency so
much that even with a 10-fold cAMP IC50/Ki shift, very potent
functional agonists were obtained (e.g., 15 and 18). A general
preference for the R stereochemistry at the piperidine C2
position was observed and is demonstrated by the 60-fold greater
potency of 19 versus ent-(S)-19.
The quinoline 4-alkoxy substituent was varied via Mitsunobu
etherification, and two acyclic aminopropyl ethers are shown in
Table 2 (20 and 21). As was observed in the GnRH optimization
of the related quinolone series,14 these acyclic aminopropyl
ethers retain potent binding and functional activity. Extension
or truncation of the four atom chain linking the amine with the
quinoline results in dramatic decreases in potency (data not
shown), which suggests that these analogues bind within the well
established somatostatin β-turn pharmacophore. Binding in this
mode would require the aminoalkyl chain of 20 and 21 to occupy
the same space as the side chain of somatostatin Lys9.2 Substitu-
tion of the linking chain was not tolerated. Replacement of the
3,5-dimethylphenyl substituent at the quinoline C3 position was
tolerated (see 22 and 23), and 3-hydroxymethylphenyl provided
near equivalent binding and functional potency.
Within the 3,6-diarylquinoline series, excellent selectivity
versus other sst subtypes was observed (e.g., >1000-fold for 19
and 21). Additionally, among selected agonists within this series,
good selectivity versus off-target GPCRs was observed. In a
screen of 116 GPCRs, 9 and 19 were found to bind to or inhibit 4
and 12 receptors with Ki or IC50 values <1 uM, respectively.
The reductions in logD observed for compounds in Table 1
wereaccompanied byimprovementinpharmacokinetic properties
(see Table 3), and these compounds were suitable for dosing in rat
pharmacodynamic studies. The moderate bioavailabilty observed
with 19 and 21 is notable among small molecule sst ligands; while
little published pharmacokinetic data are available, nonpeptide sst
ligands have, to date, exhibited very low bioavailability.
1
a All compounds were >95% pure by HPLC and characterized by H
NMR and HRMS. Values represent the numerical average of at least two
experiments. Interassay variability was (25% for the binding assay (Ki)
and for the cAMP assay (IC50).
cAMP IC50/Ki ratio as a function of logD (or, as in Figure 2, a
larger set of calculated logD) reveals an apparent threshold
ClogD below which minimal cAMP IC50/Ki shifts are observed
(threshold ClogD ∼ 2.1 as indicated by the vertical line in
Figure 2). The discovery of this threshold was facilitated by the
parallel synthesis of >200 analogues and rapid assays for binding,
functional potency, and logD. Apart from the relationship to
To investigate the in vivo activity of compounds from this
series, the ability of selected compounds to inhibit GH release
was assessed in Sprague-Dawley rats. GH is secreted from the
anterior pituitary gland in a pulsatile cycle that is controlled by
GHRH and somatostatin,20,21 and the resulting dynamic peaks
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Table 2. sst2 Binding Affinities and Functional Potency for
dose-dependent decrease in GH secretion (38 and 91% reduc-
tion in plasma GH AUC following administration of 0.2 and
2 mg/kg, respectively). Similar effects on GH secretion were seen
with the sst2 agonists 9 and 19 (data not shown). Administration
of the peptide agonist octreotide (50 μg/kg resulted in a 99%
reduction in plasma GH AUC). The in vivo potency of 21
approaches that of the octreotide, and taken together, the results
demonstrate that 21 possesses potent in vivo GH suppressing activity.
Test Compoundsa
Figure 3. Effect of systemic administration of 21 on GH release.
(A) Plasma GH concentration as a function of time following iv
administration of octreotide (0.05 mg/kg) or 21 (0.2 and 2 mg/kg)
at t = -50 min followed by GH secretagogue (t = 0 min). (B) AUC
calculated from data in panel A for 21 (0.2 and 2 mg/kg) and octreotide
(0.05 mg/kg). *p < 0.05. **p < 0.005.
1
a All compounds were >95% pure by HPLC and characterized by H
NMR and HRMS. Values represent the numerical average of at least two
experiments. Interassay variability was (25% for the binding assay (Ki)
and for the cAMP assay (IC50).
Table 3. Pharmacokinetic Data for Selected Compounds
The ability of sst2 agonists to inhibit ocular neovascularization
was studied in the rat laser-induced choroidal neovascularization
model, a model that mimics aspects of wet AMD.24 Local
(intravitreal) dosing enabled an assessment of the effects of
sst2 agonists acting on receptors in the eye. Intraocular admin-
istration of 21 (5 or 15 μg) once every 4 days demonstrated a
dose-dependent antiangiogenic effect as evidenced by a 35 and
53% reduction in neovascular lesion area with 5 or 15 μg per eye,
respectively (Figure 4). The known antiangiogenic compound,
a
a
a
compound
species
Clp
t1/2
Vdss
Fa (%)
9
dogb
ratb
dogc
ratd
5.0
14
7.1
52
0.55
3.7
0.094
3.1
ND
27
19
21
11
5.7
ND
2.9
9.4
17
a Plasma clearance (Clp) in mL/min/kg; plasma half-life (t1/2) in h;
steady-state volume of distribution (Vdss) in L/kg; and oral bioavail-
c
ability (F). b 2 mg/kg iv dose and 10 mg/kg po dose. 0.125 mg/kg
iv dose. d 2 mg/kg iv dose and 5 mg/kg po dose.
and troughs of GH in the plasma can confound the in vivo
assessment of the effects of sst2 agonists on GH levels. To
overcome this confounding factor, administration of a GH
secretagogue was used to strongly increase the secretion of GH
such that the normal GH pulses became insignificant. Impor-
tantly, GH secretion induced by GH secretagogues remains
sensitive to the inhibitory effects of somatostatin.22 To assess
the in vivo effects of our sst2 agonists, anesthetized rats were
dosed intravenously with compound 21, followed by a GH
secretagogue challenge 50 min later. Plasma GH levels were
measured every 5-15 min,23 and the data were plotted as both
plasma GH concentration as a function of time and as the area
under the curve (AUC, Figure 3). In this model, 21 caused a
Figure 4. Effect of intraocular administration of 21 on ocular neovas-
cular response. Neovasular lesion size following intraocular administra-
tion of 21 (5 or 15 μg/eye) or triamcinolone (50 μg/eye). See the text
and ref 25. *p < 0.005.
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triamcinolone acetonide, demonstrated an 81% reduction in
neovascular lesion area at a dose of 50 μg/eye. The maximal
antiangiogenic effects of 21 could not be determined as the
maximum feasible dose of this compound was limited by its
aqueous solubility. These results suggest that local delivery of sst2
agonists could be useful for the treatment of neovascular eye
diseases such as wet AMD and PDR.
7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-2-
yl]ethoxy}-N-(pyrimidin-4-yl)quinoline-6-carboxamide (3).
1H NMR (CD3OD, 500 MHz): δ 8.90 (s, 1H), 8.72 (d, J = 5.6 Hz,
1H), 8.35 (dd, J = 5.8, 1.4 Hz, 1H), 8.11 (s, 1H), 7.52 (s, 1H), 7.09 (d,
J = 16.5 Hz, 5H), 3.89-3.74 (m, 2H), 3.03 (s, 1H), 2.94-2.82 (m, 1H), 2.38
(s, 6H), 2.09-1.94(m, 2H), 1.89-1.50(m, 5H), 1.47-1.34(m, 1H), 1.26-
1.14 (m, 1H). HRMS [M þ H]þ calculated, 532.211; observed, 532.2128.
7-Chloro-3-(3,5-dimethylphenyl)-6-(4-fluorophenyl)-
4-{2-[(2R)-piperidin-2-yl]ethoxy}quinoline (4). 1H NMR
(CD3OD, 500 MHz): δ 8.75 (s, 1H), 8.20 (s, 1H), 8.16 (s, 1H),
7.59-7.53 (m, 2H), 7.24 (t, J = 8.6 Hz, 4H), 7.13 (s, 1H), 3.89-3.85 (m,
2H), 2.90 (d, J = 12.1 Hz, 1H), 2.56-2.50 (m, 1H), 2.51-2.37 (m, 7H),
1.75-1.66 (m, 2H), 1.62-1.49 (m, 2H), 1.46 (d, J = 13.1 Hz, 1H),
1.38-1.17 (m, 2H), 1.00-0.90 (m, 1H). HRMS [M þ H]þ calculated,
489.2103; observed, 487.2101.
3-(3,5-Dimethylphenyl)-6-(4-fluorophenyl)-4-[2-(piperidin-
2-yl)ethoxy]quinoline (5). 1H NMR (CD3OD, 500 MHz): δ 8.95-
8.91 (m, 1H), 8.66 (d, J = 11.1 Hz, 1H), 8.44-8.28 (m, 2H), 8.19
(s, 2H), 7.94-7.89 (m, 2H), 7.41 (t, J = 8.7 Hz, 2H), 7.30 (s, 2H), 7.16
(s, 1H), 4.00-3.87 (m, 2H), 3.26 (d, J = 12.7 Hz, 1H) 3.13 (s, 1H),
2.87-2.76 (m, 1H), 2.39 (s, 6H), 2.12-2.04 (m, 1H), 1.81-1.60 (m, 4H),
1.56-1.44 (m, 1H), 1.38-1.15 (m, 2H). HRMS [M þ H]þ calculated,
455.2499; observed, 455.2493.
The potential utility of sst2 agonists for the treatment of ocular
angiogenic diseases has been assessed clinically using the mar-
keted peptides octreotide and lanreotide with mixed results.
Several phase 2 studies of advanced nonproliferative diabetic
retinopathy patients treated with octreotide showed encouraging
reductions in disease progression;12,13 however, the results of
two subsequent prospective, controlled phase 3 studies were
ambiguous.25 Likewise, a small pilot study with lanreotide in
patients with wet AMD suggested a potential positive impact on
disease progression, but the trial was small, and the data did not
reach statistical significance. It is worth noting that in the studies
reported to date, octreotide and lanreotide were administered
systemically, and controlled clinical trials in which sst2 agonists
are delivered locally to the eye have not yet been performed.
Our results suggest that local delivery of sst2 agonists could be
useful for the treatment of neovascular eye diseases, although
further clinical studies will be necessary to fully elucidate the
potential role for sst2 agonists in the treatment of PDR and AMD.
The 3,6-diarylquinoline agonists disclosed here represent useful
tools for the preclinical study of sst2, although further improve-
ment in aqueous solubility may be needed to achieve maximal
inhibition of ocular neovascularization and the development a
potentially useful therapeutic.
Analogues 8-23 were prepared according to the published synthetic
route (see ref 19 and the Supporting Information, Scheme S1), and the
general procedure is exemplified below for 19.
7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-2-
yl]ethoxy}-6-(pyridin-3-yl)quinoline (8). 1H NMR (CD3OD,
500 MHz): δ 8.80 (s, 1H), 8.74 (dd, J = 2.3, 0.9 Hz, 1H), 8.65 (dd,
J = 4.9, 1.6 Hz, 1H), 8.29 (s, 1H), 8.22 (s, 1H), 8.08 (dt, J = 7.9, 1.9 Hz,
1H), 7.61 (ddd, J = 7.9, 5.0, 0.9 Hz, 1H), 7.25 (s, 2H), 7.14 (s, 1H),
3.93-3.85 (m, 2H), 2.90 (d, J = 12.3 Hz, 1H), 2.57-2.50 (m, 1H),
2.51-2.39 (m, 7H), 1.75-1.66 (m, 2H), 1.63-1.44 (m, 3H),
1.38-1.28 (m, 1H), 1.27-1.17 (m, 1H), 0.99-0.90 (m, 1H). HRMS
[M þ H]þ calculated, 472.2150; observed, 472.2160.
’ EXPERIMENTAL SECTION
1
General Experimental Information. H NMR spectra were re-
5-[7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-
2-yl]ethoxy}quinolin-6-yl]pyridin-2(1H)-one (9). 1H NMR
(CD3OD, 500 MHz): δ 8.92 (s, 1H), 8.32 (s, 1H), 8.26 (s, 1H), 7.84
(dd, J = 9.4, 2.7 Hz, 1H), 7.72 (d, J = 2.6 Hz, 1H), 7.26 (s, 2H), 7.21 (s,
1H), 6.68 (d, J = 9.4 Hz, 1H), 4.10-3.99 (m, 2H), 3.34 (d, J = 13.0 Hz,
1H), 3.16 (s, 1H), 2.94-2.86 (m, 1H), 2.42 (s, 6H), 2.16-2.08 (m,
1H), 1.90-1.77 (m, 3H), 1.76 (d, J = 14.3 Hz, 1H), 1.66-1.55 (m, 1H),
1.50-1.38 (m, 1H), 1.38-1.26 (m, 1H). HRMS [M þ H]þ calculated,
488.2099; observed, 488.2107.
5-[7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-
2-yl]ethoxy}quinolin-6-yl]pyridin-2-amine (10). 1H NMR
(CD3OD, 500 MHz): δ 8.79 (s, 1H), 8.56-8.55 (m, 1H), 8.29 (s,
1H), 8.21 (s, 1H), 8.05 (dd, J = 8.3, 2.5 Hz, 1H), 7.62 (dd, J = 8.3, 0.7 Hz,
1H), 7.25 (s, 2H), 7.14 (s, 1H), 3.93-3.85 (m, 2H), 2.91 (dd, J = 12.3,
3.0 Hz, 1H), 2.57-2.49 (m, 1H), 2.48-2.38 (m, 7H) 1.75-1.67 (m,
2H), 1.62-1.50 (m, 2H), 1.46 (d, J = 13.2 Hz, 1H), 1.38-1.28 (m, 1H),
1.28-1.17 (m, 1H), 1.01-0.91 (m, 1H). HRMS [M þ H]þ calculated,
487.2259; observed, 487.2261.
7-Chloro-3-(3,5-dimethylphenyl)-6-(6-methoxypyridin-3-
yl)-4-{2-[(2R)-piperidin-2-yl]ethoxy}quinoline (11). 1H NMR
(CD3OD, 500 MHz): δ 8.75 (s, 1H), 8.32-8.27 (m, 1H), 8.22 (s, 1H),
8.16 (s, 1H), 7.89 (dd, J = 8.6, 2.5 Hz, 1H), 7.24 (s, 2H), 7.13 (s, 1H),
6.93 (dd, J = 8.6, 0.8 Hz, 1H), 3.99 (s, 3H), 3.91-3.82 (m, 2H), 2.90 (dd,
J = 12.2, 3.0 Hz, 1H), 2.57-2.52 (m, 1H), 2.51-2.37 (m, 7H), 1.76-
1.66 (m, 2H), 1.63-1.49 (m, 2H), 1.46 (d, J = 13.2 Hz, 1H), 1.38-1.17
(m, 2H), 1.01-0.91 (m, 1H). HRMS [M þ H]þ calculated, 502.2256;
observed, 502.2262.
corded using Varian VXR spectrometers. Chemical shifts are reported in
δ (ppm) using tetramethylsilane (δ 0 ppm) as an internal standard. High-
resolution mass spectral data were obtained using a Bruker Daltonics
FTICR/MS in electrospray ionization mode. HPLC spectra were obtained
using Agilent 1100 HPLC systems. All animal studies were reviewed and
approved by Merck's Institutional Animal Care and Use Committee.
Purity Determination. Analytical reversed phase high-perfor-
mance liquid chromatography-mass spectrometry (LC-MS) was per-
formed on an Agilent 1100 HPLC system equipped with an
autosampler, a high-pressure pump (a binary pump was used), a single
quadrupole mass spectrometer, and a photodiode array detector. The
purity of the final compounds was determined using UV detection
(λ = 214 nm). The chromatographic method employed the following:
column, YMC J'sphere C18 (4 μM, 3.0 mm ꢀ 50 mm); mobile phase A,
0.05% TFA in water; mobile phase B, acetonitrile with 0.05% TFA; flow
rate, 1.1 mL/min; elution profile, gradient elution from 5 to 100% B over
3.6 min followed by isocratic elution at 100% B for 0.45 min. According
to these methods, purities for compounds 2-23 were >98%. Com-
pounds 2-7 were prepared as described previously.14-18
7-Chloro-3-(3,5-dimethylphenyl)-6-(4-fluorophenyl)-
4-{2-[(2R)-piperidin-2-yl]ethoxy}quinolin-2(1H)-one (2). H
1
NMR (CD3OD, 500 MHz): δ 7.81 (s, 1H), 7.55 (s, 1H), 7.51-7.47 (m,
2H), 7.24-7.18 (m, 2H), 7.09 (s, 1H), 7.07 (s, 2H), 3.84 (dt, J = 10.2,
5.1 Hz, 1H), 3.77 (td, J = 9.3, 4.2 Hz, 1H), 2.94 (s, 1H), 2.87-2.76 (m,
1H), 2.39-2.32 (m, 7H), 2.02-1.94 (m, 1H), 1.83 (d, J = 14.5 Hz, 1H),
1.76 (d, J = 13.4 Hz, 1H), 1.72-1.63 (m, 1H), 1.62-1.49 (m, 2H),
1.39-1.29 (m, 1H), 1.22-1.12 (m, 1H). HRMS [M þ H]þ calculated,
505.2053; observed, 505.207.
7-Chloro-6-(6-chloropyridin-3-yl)-3-(3,5-dimethylphenyl)-
4-{2-[(2R)-piperidin-2-yl]ethoxy}quinoline (12). 1H NMR
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(CD3OD, 500 MHz): δ 8.79 (s, 1H), 8.56-8.55 (m, 1H), 8.29 (s, 1H),
8.21 (s, 1H), 8.05 (dd, J = 8.3, 2.5 Hz, 1H), 7.62 (dd, J = 8.3, 0.7 Hz, 1H),
7.25 (s, 2H), 7.14 (s, 1H), 3.93-3.85 (m, 2H), 2.91 (dd, J = 12.3, 3.0 Hz,
1H), 2.56-2.49 (m, 1H), 2.49-2.37 (m, 7H), 1.75-1.67 (m, 2H),
1.62-1.50 (m, 2H), 1.46 (d, J = 13.2 Hz, 1H), 1.38-1.25 (m, 1H),
1.26-1.17 (m, 1H), 1.01-0.91 (m, 1H). HRMS [M þ H]þ calculated,
506.1760; observed, 506.1768.
The warmed product 25 is used directly in next step (410 g, yield
95%). (The anilinoacrylate can be recrystallized from petroleum ether
as slender white needles.) 1H NMR (DMSO-d6, 400 MHz): δ 10.55
(d, J = 14.0 Hz, 1H), 8.29 (d, J = 13.6 Hz, 1H), 7.83 (d, J = 8.8 Hz, 1H),
7.67 (d, J = 2.4 Hz, 1H), 7.10 (dd, J = 8.4, 2.4 Hz, 1H), 4.17 (q, J =
7.2 Hz, 2H), 4.09 (q, J = 7.2 Hz, 2H), 1.23 (d, J = 7.2 Hz, 3H), 1.19 (d,
J = 7.2 Hz, 3H). ESI-MS m/z (M þ Hþ): 424.0, 426.0.
Ethyl 7-Chloro-4-hydroxy-6-iodoquinoline-3-carboxylate (26;
Supporting Information, Scheme S1). Biphenyl ether (1.5 L) and
compound 25 from the previous step were heated at reflux for 1 h
before being cooled and filtered. The solids were washed with
petroleum to obtain 26 (330.0 g, yield 90%). ESI-MS m/z (M þ
Hþ): 377.9, 379.9.
7-Chloro-3-(3,5-dimethylphenyl)-6-(6-fluoropyridin-3-
yl)-4-[2-(piperidin-2-yl)ethoxy]quinoline (13). 1H NMR
(CD3OD, 500 MHz): δ 8.79 (s, 1H), 8.38 (d, J = 2.5 Hz, 1H), 8.28
(s, 1H), 8.21-8.15 (m, 2H), 7.25-7.21 (m, 3H), 7.14 (s, 1H), 3.92-
3.83 (m, 2H), 2.94-2.86 (m, 1H), 2.56-2.49 (m, 1H), 2.53-2.37 (m,
7H), 1.77-1.67 (m, 2H), 1.63-1.49 (m, 2H), 1.46 (d, J = 13.1 Hz, 1H),
1.38-1.25 (m, 1H), 1.26-1.18 (m, 1H), 1.00-0.90 (m, 1H). HRMS
[M þ H]þ calculated, 490.2056; observed, 490.2064.
7-Chloro-4-hydroxy-6-iodoquinoline-3-carboxylic Acid (27; Sup-
porting Information, Scheme S1). Compound 26 (312.5 g, 0.827 mol)
was mixed with 10% aqueous sodium hydroxide (1 L), and the mixture
was heated at reflux until all solids dissolved. The reaction mixture was
cooled, and the aqueous solution was separated from any oil present.
The aqueous solution was acidified to pH 3, and solids were collected by
filtration and washed with water until the filtrate measured pH 7. The
solid was washed with two 2.5 L portions of methanol to remove the
7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-2-
1
yl]ethoxy}-6-(pyridin-4-yl)quinoline (14). H NMR (CD3OD,
500 MHz): δ 8.80 (s, 1H), 8.69 (dd, J = 4.5, 1.7 Hz, 2H), 8.28 (m, 1H),
8.22 (s, 1H), 7.65 (dd, J = 7.6, 4.5 Hz, 2H), 7.25 (s, 2H), 7.14 (s, 1H),
3.92-3.84 (m, 2H), 2.90 (d, J = 12.2 Hz, 1H), 2.56-2.49 (m, 1H),
2.49-2.39 (m, 7H), 1.76-1.66 (m, 2H), 1.64-1.44 (m, 3H), 1.38-
1.27 (m, 1H), 1.27-1.16 (m, 1H), 1.00-0.90 (m, 1H). HRMS
[M þ H]þ calculated, 472.2150; observed, 472.2150.
1
major impurities and provide pure 27 (281.7 g, yield 97%). H NMR
(DMSO-d6, 400 MHz): δ 14.80 (br s, 1H), 12.40 (br s, 1H), 8.94 (s,
1H), 8.67 (s, 1H), 7.95 (s, 1H). ESI-MS m/z (M þ Hþ): 349.9, 351.9.
7-Chloro-6-iodoquinolin-4-ol (28; Supporting Information,
Scheme S1). The carboxylic acid 27 (281.7 g, 0.806 mol) was suspended
in biphenyl ether (1 L) and heated at reflux for 1 h before being cooled
and filtered. The collected solids were washed with two 2.5 L portions of
petroleum ether, two 2.5 L portions of methanol, two 2.5 L portions of
water, and two 2.5 L portions of acetone to remove the major impurities
4-[7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-
2-yl]ethoxy}quinolin-6-yl]phenol (15). 1H NMR (CD3OD, 500
MHz): δ 8.70 (s, 1H), 8.16 (s, 1H), 8.11 (s, 1H), 7.32-7.23 (m, 4H),
7.13 (s, 1H), 6.80 (d, J = 8.1 Hz, 2H), 3.90-3.83 (m, 2H), 2.91 (d, J =
12.2 Hz, 1H), 2.63-2.57 (m, 1H), 2.51-2.44 (m, 1H), 2.41 (s, 6H),
1.76-1.67 (m, 2H), 1.62-1.42 (m, 3H), 1.38-1.22 (m, 2H),
1.01-0.92 (m, 1H). HRMS [M þ H]þ calculated, 487.2147; observed,
487.2146.
1
and provide pure 28 (241.1 g, yield 97%). H NMR (DMSO-d6, 400
3-[7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperidin-
2-yl]ethoxy}quinolin-6-yl]phenol (16). 1H NMR (CD3OD, 500
MHz): δ 8.73 (s, 1H), 8.18 (s, 1H), 8.11 (s, 1H), 7.29-7.20 (m, 3H),
7.12 (s, 1H), 6.94-6.80 (m, 3H), 3.88-3.82 (m, 2H), 2.89 (d, J = 12.0
Hz, 1H), 2.55 (s, 1H), 2.60-2.28 (m, 7H), 1.75-1.64 (m, 2H), 1.61-
1.43 (m, 3H), 1.38-1.17 (m, 2H), 1.00-0.90 (m, 1H). HRMS
[M þ H]þ calculated, 487.2147; observed, 487.2149.
MHz): δ 11.85 (br s, 1H), 8.48 (s, 1H), 7.93 (d, J = 7.6 Hz, 1H), 7.72
(s, 1H), 6.06 (d, J = 7.2 Hz, 1H).
3-Bromo-7-chloro-6-iodoquinolin-4-ol (29; Supporting Informa-
tion, Scheme S1). Compound 28 (120.0 g, 0.393 mol) was dissolved
in acetic acid (1800 mL) and treated with NBS (70.0 g, 0.393 mol)
before being heated at 60 ꢀC for 2 h, cooled, and evaporated. Saturated
aqueous NaHCO3 was added, and the resulting solid was collected by
filtration. The solid was washed with two 2.5 L portions of water and two
2.5 L portions of acetone to remove the major impurities and provide
pure 29 (133.0 g, yield 88%). 1H NMR (DMSO-d6, 400 MHz): δ 8.52
(s, 1H), 8.49 (s, 1H), 7.74 (s, 1H). ESI-MS m/z (M þ Hþ): 383.8,
385.8, 387.8.
{4-[7-Chloro-3-(3,5-dimethylphenyl)-4-{2-[(2R)-piperi-
din-2-yl]ethoxy}quinolin-6-yl]phenyl}methanol (17). 1H
NMR (CD3OD, 500 MHz): δ 8.75 (s, 1H), 8.21 (s, 1H), 8.16 (s,
1H), 7.55-7.47 (m, 4H), 7.25 (s, 2H), 7.14 (s, 1H), 4.71 (s, 2H), 3.92
-3.84 (m, 2H), 2.89 (d, J = 12.1 Hz, 1H), 2.57-2.50 (m, 1H),
2.50-2.38 (m, 7H), 1.74-1.65 (m, 2H), 1.61-1.42 (m, 3H), 1.38-
1.18 (m, 2H), 1.00-0.90 (m, 1H). HRMS [M þ H]þ calculated,
501.2303; observed, 501.2305.
tert-Butyl(2R)-2-{2-[(3-bromo-7-chloro-6-iodoquinolin-4-yl)-
oxy]ethyl}piperidine-1-carboxylate (30; Supporting Information,
Scheme S1). Quinolinol 29 (7.69 g, 30.0 mmol), tert-butyl(2R)-2-(2-
hydroxyethyl)piperidine-1-carboxylate (4.59 g, 20.0 mmol), PPh3
(6.30 g, 24.0 mmol), and THF (100 mL) were combined in a
500 mL round flask, which was sealed with a rubber stopper and
sonicated for 3 min at room temperature. Sonication was stopped, and
diisopropylazodicarboxylate (4.85 g, 24.0 mmol) was added via syringe
over 10 min, after which the reaction was again sonicated for 40 min.
During the sonication, all solids dissolved. After this period, THF was
evaporated, and the residue was purified by flash chromatography
(EtOAc/hexanes) to provide 30 as a yellow solid (7.39 g, 62%). ESI-
MS m/z (M þ Hþ): 595.
3-{7-Chloro-3-(3,5-dimethylphenyl)-4-[2-(piperidin-2-
yl)ethoxy]quinolin-6-yl}benzamide (18). 1H NMR (CD3OD,
500 MHz): δ 8.77 (s, 1H), 8.26 (s, 1H), 8.18 (s, 1H), 8.07 (d, J = 2.1 Hz,
1H), 8.01-7.97 (m, 1H), 7.74 (dd, J = 7.7, 1.7 Hz, 1H), 7.62 (t, J = 7.7
Hz, 1H), 7.25 (s, 2H), 7.14 (s, 1H), 3.92-3.83 (m, 2H), 2.88 (d, J = 12.1
Hz, 1H), 2.58-2.52 (m, 1H), 2.51-2.35 (m, 7H), 1.76-1.64 (m, 2H),
1.61-1.42 (m, 3H), 1.37-1.26 (m, 1H), 1.26-1.15 (m, 1H), 1.00-
0.90 (m, 1H). HRMS [M þ H]þ calculated, 514.2256; observed,
514.2258.
General Procedure for the Syntheses of 8-23 (See the
Supporting Information, Scheme S1, and Ref 19): Synthesis
of 7-Chloro-3-(3,5-dimethylphenyl)-6-(1-methyl-1H-pyra-
zol-4-yl)-4-{2-[(2R)-piperidin-2-yl]ethoxy}quinoline (19). Diethyl
{[(3-Chloro-4-iodophenyl)amino]methylene}malonate (25; Sup-
porting Information, Scheme S1). Boiling chips were added to a
mixture of 3-chloro-4-iodo-phenylamine (24, 260.0 g, 1.027 mol) and
2-ethoxymethylene-malonic acid diethyl ester (244.2 g, 1.130 mol),
and the mixture was heated at 120 ꢀC for 1 h with evolution of ethanol.
tert-Butyl(2R)-2-(2-{[3-bromo-7-chloro-6-(1-methyl-1H-pyrazol-4-
yl)quinolin-4-yl]oxy}ethyl)piperidine-1-carboxylate (31; Supporting
Information, Scheme S1). A mixture of 30 (696 mg, 1 mmol),
1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole
(315 mg, 1.5 mmol), and Pd(dppf)Cl2 dichloromethane adduct (40 mg,
0.05 mmol) in 1 M aqueous Cs2CO3 (5 mL) and THF (10 mL) was
heated in a sealed 5 mL tube in a Biotage Initiator microwave at 80 ꢀC for
15 min. The layers were separated, and the aqueous layer was extracted
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Journal of Medicinal Chemistry
ARTICLE
with THF (2 ꢀ 5 mL). The combined THF solutions were concen-
trated, and the residue was dissolved in CH2Cl2 (150 mL), washed with
brine, dried (Na2SO4), concentrated under reduced pressure, and
purified by flash chromatography (SiO2, EtOAc/hexanes) to afford 31
(452 mg, 83%). ESI-MS m/z (M þ Hþ): 493.
30 min at 4 ꢀC. Membranes were resuspended in fresh binding buffer
containing protease inhibitors and stored at -70 ꢀC.
Binding Assay Conditions. Final assay conditions for the receptor
binding assay were 0-10000 nM compound, 0.1 nM 125I-somatostatin-
14 (Amersham, IM161), 2.5-50 μg membrane, and 0.5-2% DMSO to
a final assay volume of 1 mL in binding buffer containing protease
inhibitors. 125I-somatostatin-14 and membranes were incubated for
30 min at room temperature followed by addition of compound
resuspended in DMSO, and the mixture was incubated at room
temperature for an additional 3 h with gentle shaking. Membrane-bound
125I-somatostatin-14 was separated from unbound 125I-somatostatin-14
by vacuum filtration through Packard Unifilter GF/B filter plates
(Packard, 6005177) pretreated with 0.1% polyethyleneimine followed
by washing with 5 mL of cold 50 mM Tris-HCl, pH 7.8. Sixty microliters
of Microscint-20 scintillation fluid (Packard, 6013621) was added, and
the bound 125I-somatostatin-14 was quantitated using a Packard Top-
count scintillation counter.
Inhibiton of Forskolin-Induced cAMP Release Assay. CHO
cells expressing a GRqi5 subunit were grown to confluence in DMEM/
F12 media (Cellgro, 16405CV) with 10% FBS (Gibco 16000044). Test
compounds were added to the cell growth media to a final concentration
of 0-10000 nM and incubated for 10 min at 37 ꢀC. Forskolin (Sigma,
F6886) was added to a final concentration of 12.5 μM, the cells were
incubated at 37 ꢀC for 40 min, and cAMP levels were assayed using a
DiscoverX HitHunter cAMP kit (DiscoverX, catalog #900075) follow-
ing the manufacturer's recommended protocol. Luminescence was
measured using a GE Envision plate reader.
GH-Release Assay Protocol. Female Wistar rats (200-250 g)
with indwelling jugular veinal and carotid arterial cannulas (ordered
from Charles River Laboratories) were used. First, rats were anesthe-
tized by IP injection with pentobarbital (Nembutal; 50 mg/kg). Once
unconscious, vehicle, test compound, or octreotide (Amercian Peptide;
50 μg/kg) was delivered via jugular cannula. Control blood samples
(0.3 mL) were collected via carotid cannula at 40 and 50 min post
compound administration. A GH secretagogue was then delivered
(10 μg/kg) via jugular cannula, and blood samples (0.3 mL) were
collected via carotid cannula at 5, 10, 15, 20, 30, and 45 min post-GH
secretagogue administration. Blood samples collected were centrifuged
at 1600g for 20 min at 4 ꢀC. Serum was removed and assayed for GH
content by a double antibody RIA procedure.
Rat Laser Choroidal Neovascularization (CNV) Model
Protocol. Male Brown Norway rats (175-225 g) from Charles River
Laboratories were used. Animals were lasered and perfused as described
previously.24 Vehicle and test compound were administered via intravi-
treal injection. After lasering of anesthetized rat, a local anesthetic, 0.5%
proparacaine HCl (Henry Schein), was administered to each eye. A 27G
needle was used to make a small hole in the eye 3 mm posterior to iris
angled 45ꢀ toward the optic nerve. A 30G blunt needle was then used to
administer 5 μL vehicle (5% ethanol in PBS), test compound, or
triamcinolone (Kenalog-10; Henry Schein) through the initial hole.
Rats were injected days 0, 4, and 8 with vehicle or test compound, while
triamcinolone was administered only on day 0.
7-Chloro-3-(3,5-dimethylphenyl)-6-(1-methyl-1H-pyrazol-4-yl)-
4-{2-[(2R)-piperidin-2-yl]ethoxy}quinoline (19). A mixture of 31 (55
mg, 0.1 mmol), 3,5-dimethylphenylboronic acid (20 mg, 0.13 mmol),
and Pd(dppf)Cl2 dichloromethane adduct (4 mg, 0.005 mmol) in 1 M
aqueous Cs2CO3 (0.5 mL) and THF (2 mL) was heated in a sealed 5 mL
tube in a Biotage Initiator microwave at 120 ꢀC for 10 min. The layers
were separated, and the aqueous layer was extracted with THF (2 ꢀ
2 mL). The combined THF solutions were treated with Quadra Pure
TU for 2 h to remove Pd, before being filtered and concentrated under
reduced pressure to afford a brown residue, which was treated with
TFA/CH2Cl2 (1:1, 2 mL) and stirred at room temperature for 1 h. The
reaction mixture was concentrated under reduced pressure and purified
by LCMS to afford the pure 19 as a slightly yellow solid (TFA salt, 65
mg, 79%). 1H NMR (CD3OD, 600 MHz): δ 8.81 (s, 1H), 8.35 (s, 1H),
8.21 (s, 1H), 8.19 (s, 1H), 7.92 (s, 1H), 7.26 (s, 2H), 7.19 (s, 1H), 3.96-
4.05 (m, 5H), 3.35 (d, J = 13.0 Hz, 1H), 3.14-3.20 (m, 1H), 2.92 (dt, J =
12.3, 2.9 Hz, 1H), 2.08-2.15 (m, 1H), 1.73-1.90 (m, 4H), 1.56-1.66
(m, 1H); 1.40-1.49 (m, 1H), 1.26-1.34 (m, 1H). HRMS m/z
475.2227 (C28H31ClN4O þ Hþ requires 475.2259).
3-[4-(3-Aminopropoxy)-7-chloro-3-(3,5-dimethylphenyl)quinolin-
6-yl]benzamide (20). 1H NMR (CD3OD, 500 MHz): δ 8.83 (s, 1H),
8.07 (d, J = 8.6 Hz, 1H), 8.02 (t, J = 4.1 Hz, 1H), 7.96 (dt, J = 13.7, 3.0 Hz,
1H), 7.75 (d, J = 8.6 Hz, 1H), 7.68 (dt, J = 8.6, 1.1 Hz, 1H), 7.61 (t, J =
7.7 Hz, 1H), 7.28 (s, 2H), 7.16 (s, 1H), 3.82 (t, J = 5.8 Hz, 2H), 2.84 (t,
J = 7.9 Hz, 2H), 1.98-1.90 (m, 2H). HRMS [M þ H]þ calculated,
460.1787; observed, 460.1809.
3-[4-(3-Aminopropoxy)-7-chloro-3-(3,5-dimethylphenyl)quinolin-
6-yl]phenol (21). 1H NMR (CD3OD, 500 MHz): δ 8.77-8.73 (m, 1H),
8.24-8.16 (m, 1H), 8.14 (s, 1H), 7.33-7.27 (m, 1H), 7.25 (s, 2H), 7.13
(s, 1H), 6.98-6.92 (m, 2H), 6.89-6.86 (m, 1H), 3.87-3.82 (m, 2H),
2.74-2.68 (m, 2H), 2.41 (s, 6H), 1.83-1.75 (m, 2H). HRMS [M þ
H]þ calculated, 433.1677; observed, 433.1671.
{3-[7-Chloro-6-(1-methyl-1H-pyrazol-4-yl)-4-{2-[(2R)-piperidin-2-
1
yl]ethoxy}quinolin-3-yl]phenyl}methanol (22). H NMR (CD3OD,
500 MHz): δ 8.76 (s, 1H), 8.33 (s, 1H), 8.14 (d, J = 3.2 Hz, 2H), 7.91 (d,
J = 0.8 Hz, 1H), 7.65 (s, 1H), 7.58-7.51 (m, 2H), 7.47 (d, J = 6.8 Hz,
1H), 4.72 (s, 2H), 4.00 (s, 3H), 3.93-3.83 (m, 2H), 2.98 (d, J= 12.3 Hz, 1H),
2.68-2.61 (m, 1H), 2.56 (td, J = 12.1, 2.9 Hz, 1H), 1.84-1.70 (m, 2H),
1.69-1.50 (m, 3H), 1.44-1.25 (m, 2H), 1.08-0.98 (m, 1H). HRMS
[M þ H]þ calculated, 477.2057; observed, 477.2051.
[(4-{2-[(2R)-Piperidin-2-yl]ethoxy}quinoline-3,6-diyl)dibenzene-
3,1-diyl]dimethanol (23). 1H NMR (CD3OD, 500 MHz): δ 8.78
(s, 1H), 8.46 (d, J = 1.7 Hz, 1H), 8.14-8.09 (m, 2H), 7.80 (s, 1H),
7.73-7.67 (m, 2H), 7.61-7.46 (m, 4H), 7.43 (d, J = 7.6 Hz, 1H), 4.74
(s, 4H), 3.99-3.88 (m, 2H), 3.12 (d, J = 12.5 Hz, 1H), 2.90 (s, 1H), 2.72
(td, J = 12.4, 3.0 Hz, 1H), 1.99-1.90 (m, 1H), 1.80-1.58 (m, 3H),
1.59-1.26 (m, 3H), 1.19-1.08 (m, 1H). HRMS [M þ H]þ calculated,
469.2486; observed, 469.2491.
’ ASSOCIATED CONTENT
Somatostatin Receptor Binding Assay. Membrane Prepara-
tion. Membranes for binding assays were prepared from CHO cells
stably transfected with human sst1, sst2, sst3, sst4, or sst5 expression
constructs. Briefly, cells were washed in 1ꢀ CMF-PBS (10 mM HEPES,
1ꢀ Dulbecco's PBS) then in ice cold binding buffer (binding buffer:
50 mM Tris-HCl, pH 7.8, 5 mM MgCl2, and 1 mM EGTA). The cells
were collected in a small volume of binding buffer containing protease
inhibitors (protease inhibitors: 10 μg/mL leupeptin, 10 μg/mL pep-
statin, 200 μg/mL bacitracin, and 0.5 μg/mL aprotinin) and then
centrifuged at 25000g for 10 min at 4 ꢀC. The cell pellet was homo-
genized using a dounce homogenizer and centrifuged at 40000g for
S
Supporting Information. Synthetic scheme for analo-
b
gues 8-23. This material is available free of charge via the
Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Tel: 215-652-0821. Fax: 215-652-6345. E-mail: scott_wolkenberg@
merck.com.
2357
dx.doi.org/10.1021/jm101501b |J. Med. Chem. 2011, 54, 2351–2358

Journal of Medicinal Chemistry
ARTICLE
Present Addresses
(12) Grant, M. B.; Mames, R. N.; Fitzgerald, C.; Hazariwala, K. M.;
Cooper-DeHoff, R.; Caballero, S.; Estes, K. S. The efficacy of octreotide
in the therapy of severe nonproliferative and early proliferative diabetic
retinopathy - A randomized controlled study. Diabetes Care 2000,
23, 504–509.
(13) Boehm, B. O.; Lang, G. K.; Jehle, P. M.; Feldmann, B.; Lang,
G. E. Octreotide reduces vitreous hemorrhage and loss of visual acuity
risk in patients with high-risk proliferative diabetic retinopathy. Horm.
Metab. Res. 2001, 33, 300–306.
Novartis Institutes of BioMedical Research, 220 Massachusetts
Avenue, Cambridge, Massachusetts 02139.
¥GlaxoSmithKline, 1250 South Collegeville Road, Collegeville,
PA 19426.
^Vanderbilt Program in Drug Discovery, Vanderbilt University
Medical Center, Nashville, Tennessee 37232.
(14) DeVita, R. J.; Hollings, D. D.; Goulet, M. T.; Wyvratt, M. J.;
Fisher, M. H.; Lo, J.-L.; Yang, Y. T.; Cheng, K.; Smith, R. G. Identifica-
tion and initial structure-activity relationships of a novel non-peptide
quinolone GnRH receptor antagonist. Bioorg. Med. Chem. Lett. 1999,
9, 2615–2620.
’ ACKNOWLEDGMENT
We thank Brian Eastman for preliminary studies and Joan S.
Murphy and Charles W. Ross, III, for HRMS measurements.
(15) DeVita, R. J.; Goulet, M. T.; Wyvratt, M. J.; Fisher, M. H.; Lo,
J.-L.; Yang, Y. T.; Cheng, K.; Smith, R. G. Investigation of the
4-O-alkylamine substituent of non-peptide quinolone GnRH receptor
antagonists. Bioorg. Med. Chem. Lett. 1999, 9, 2621–2624.
(16) Walsh, T. F.; Toupence, R. B.; Young, J. R.; Huang, S. X.;
Ujjainwalla, F.; DeVita, R. J.; Goulet, M. T.; Wyvratt, M. J. J.; Fisher,
M. H.; Lo, J.-L.; Ren, N.; Yudkovitz, J. B.; Yang, Y. T.; Cheng, K.; Smith,
R. G. Potent antagonists of gonadotropin releasing hormone receptors
derived from quinolone-6-carboxamides. Bioorg. Med. Chem. Lett. 2000,
10, 443–447.
(17) Young, J. R.; Huang, S. X.; Chen, I.; Walsh, T. F.; DeVita, R. J.;
Wyvratt, M. J.; Goulet, M. T.; Ren, N.; Lo, J.-L.; Yang, Y. T.; Yudkovitz,
J. B.; Cheng, K.; Smith, R. G. Quinolones as gonadotropin releasing
hormone (GnRH) antagonists: Simultaneous optimization of the C(3)-
aryl and C(6)-substituents. Bioorg. Med. Chem. Lett. 2000, 10,
1723–1727.
(18) DeVita, R. J.; Walsh, T. F.; Young, J. R.; Jiang, J.; Ujjainwalla, F.;
Toupence, R. B.; Parikh, M.; Huang, S. X.; Fair, J. A.; Goulet, M. T.;
Wyvratt, M. J.; Lo, J.-L.; Ren, N.; Yudkovitz, J. B.; Yang, Y. T.; Cheng, K.;
Cui, J.; Mount, G.; Rohrer, S. P.; Schaeffer, J. M.; Rhodes, L.; Drisko,
J. E.; McGowan, E.; MacIntyre, D. E.; Vincent, S.; Carlin, J. R.; Cameron,
J.; Smith, R. G. A Potent, Nonpeptidyl 1H-Quinolone Antagonist for the
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’ ABBREVIATIONS USED
sst1-5, somatostatin receptor subtypes 1-5; GPCR, G protein-
coupled receptor; TSH, thyroid stimulating hormone; GHRH,
growth hormone releasing hormone; GH, growth hormone; VI-
Poma, endocrine tumor producing vasoactive intestinal peptide;
PDR, proliferative diabetic retinopathy; AMD, age-related ma-
cular degeneration; IGF-1, insulin-like growth factor 1; GnRH,
gonadotropin-releasing hormone; cAMP, cyclic adenosine
monophosphate; AUC, area under the curve
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