Antagonists of the calcium receptor I. Amino alcohol-based parathyroid hormone secretagogues

Article abstract of DOI:10.1021/jm900364m

Functional screening of the former SmithKline Beecham compound collection against the human calcium receptor (CaR) resulted in the identification of the amino alcohol-based hit 2 (IC₅₀ = 11 μM). Structure-activity studies of 2 focused on the optimization of the right- and left-hand side aromatic moieties as well as the amino alcohol linker region. Critical to the optimization of this antagonist template was the discovery that the chirality of the C-2 secondary alcohol played a key role in enhancing both CaR potency as well as selectivity over the β-adrenergic receptor subtypes. These SAR studies ultimately led to the identification of 38 (NPS 2143; SB-262470A), a potent and orally active CaR antagonist. Pharmacokinetic characterization of 38 in the rat revealed that this molecule had a large volume of distribution (11 L/kg), which resulted in a prolonged systemic exposure, protracted increases in the plasma levels of PTH, and an overall lack of net bone formation effect in a rodent model of osteoporosis.

Full text of DOI:10.1021/jm900364m

3982
J. Med. Chem. 2009, 52, 3982–3993
Antagonists of the Calcium Receptor I. Amino Alcohol-Based Parathyroid Hormone
Secretagogues
Robert W. Marquis,*,† Amparo M. Lago,† James F. Callahan,† Robert E. Lee Trout,† Maxine Gowen,‡ Eric G. DelMar,#
Bradford C. Van Wagenen,# Sarah Logan,# Scott Shimizu,# John Fox,# Edward F. Nemeth,# Zheng Yang,| Theresa Roethke,§
Brian R. Smith,§ Keith W. Ward,§ John Lee,⊥ Richard M. Keenan,† and Pradip Bhatnagar†
Departments of Medicinal Chemistry, Bone and Cartilage Biology, Drug Metabolism and Pharmacokinetics, Computational and Structural
Chemistry, and Cellular Biochemistry, GlaxoSmithKline, 1250 South CollegeVille Road, CollegeVille, PennsylVania 19426, NPS
Pharmaceuticals, 550 Hills DriVe, Bedminster, New Jersey 07921
ReceiVed March 23, 2009
Functional screening of the former SmithKline Beecham compound collection against the human calcium
receptor (CaR) resulted in the identification of the amino alcohol-based hit 2 (IC50 ) 11 µM).
Structure-activity studies of 2 focused on the optimization of the right- and left-hand side aromatic moieties
as well as the amino alcohol linker region. Critical to the optimization of this antagonist template was the
discovery that the chirality of the C-2 secondary alcohol played a key role in enhancing both CaR potency
as well as selectivity over the ꢀ-adrenergic receptor subtypes. These SAR studies ultimately led to the
identification of 38 (NPS 2143; SB-262470A), a potent and orally active CaR antagonist. Pharmacokinetic
characterization of 38 in the rat revealed that this molecule had a large volume of distribution (11 L/kg),
which resulted in a prolonged systemic exposure, protracted increases in the plasma levels of PTH, and an
overall lack of net bone formation effect in a rodent model of osteoporosis.
Introduction
Bone is a dynamically remodeling tissue balanced by the
interplay of osteoclasts that degrade bone and osteoblasts that
produce new bone. When the resorption phase of remodeling
outpaces new bone formation, the overall architecture of bone
is weakened, leading ultimately to osteoporosis.1 There are
Figure 1. Calcimimetic cinacalcet (1) and antagonist screening hit 2.
currently several marketed drugs for the prevention and treat-
ment of osteoporosis.2 The vast majority of these therapeutics
are antiresorptive agents and act to slow bone loss by inhibiting
in postmenopausal women.3 Both PTH and teriparatide exert
osteoclast activity. The bisphosphonates, estrogens, selective
their bone forming effects by activating PTH/PTHrP receptors
estrogen receptor modulators, salmon calcitonin, the receptor
on osteoblasts and osteoblast precursor cells.4
activator of NK-κB ligand (RANK-La) monoclonal antibody
denosumab, and the cathepsin K inhibitor odanacatib have all
demonstrated antiresorptive activity in human clinical trials but
offer little or no new bone building effect. Recently, a new
pharmacological approach for the treatment of osteoporosis has
been introduced to the marketplace. Daily subcutaneous injec-
tions of recombinant full-length human parathyroid hormone
(PTH) 1-84 (Nycomed) or teriparatide, the recombinant N-
terminal PTH 1-34 amino acid fragment (Lilly), stimulate new
bone formation leading to a reversal of osteoporotic bone loss
Another approach to the identification of a new bone forming
therapeutic based upon the clinically validated mechanism of
action of PTH and teriparatide, would be the development of
an agent that would elicit the secretion of PTH from the
parathyroid gland. PTH secretion is under the strict control of
the calcium receptor (CaR), a family-C, cell surface G-protein
coupled receptor that is capable of detecting minute variations
in extracellular calcium ion concentrations (Ca2+).5 Elevation
of extracellular Ca2+ concentrations activates the CaR and leads
to a suppression of PTH secretion. Small molecule CaR agonists
or allosteric activators, collectively known as calcimimetics,
mimic elevated Ca2+ concentrations and inhibit PTH secretion.6
Cinacalcet, N-[(1R)-1-(1-naphthalenyl)ethyl]-3-[3-(trifluorom-
ethyl)phenyl]-1-propanamine, (1, Amgen/NPS, Figure 1) has
therapeutic utility in controlling elevated PTH levels in patients
with hyperparathyroidism, demonstrating that pharmacological
manipulation of the CaR by a small molecule may be used in
controlling PTH secretion.7 In contrast to the inhibitory effects
of high Ca2+ levels or calcimimetics on PTH secretion, low
circulating Ca2+ levels stimulate PTH secretion. Small molecule
antagonists of the CaR, known as calcilytics or negative
allosteric modulators, mimic low extracellular Ca2+ and stimu-
late PTH secretion.8-18
* To whom correspondence should be addressed. Phone: 1-610-917-7368.
Fax: E-mail: Robert.W.Marquis@gsk.com. Address: Department of Me-
dicinal Chemistry, ImmunoInflammation Center of Excellence in Drug
Discovery, GlaxoSmithKline, 1250 South Collegeville Road, UP1110,
Collegeville, PA 19426.
†
Department of Medicinal Chemistry, GlaxoSmithKline.
Department of Bone and Cartilage Biology, GlaxoSmithKline.
Department of Drug Metabolism and Pharmacokinetics, GlaxoSmithKline.
Department of Computational and Structural Chemistry, GlaxoSmithKline.
Department of Cellular Biochemistry, GlaxoSmithKline.
NPS Pharmaceuticals.
‡
§
|
⊥
#
a Abbreviations: CaR, calcium receptor; PTH, parathyroid hormone;
RANK, receptor activator of NK-κB; PTHrP, parathyroid hormone-related
protein; HEK, human embryonic kidney; OVX, ovariectomized; SAR,
structure-activity relationship; LDA, lithium diisopropylamide; DAT,
dopamine transporter; SERT, serotonin transporter; NET, norepinephrine
transporter; CYP2D6, cytochrome P450 2D6; hERG, human ether-a-go-go
related gene; FLIPR, fluorimetric imaging plate reader.
An important aspect of the pharmacology of PTH and its
agonist fragments is the temporal nature of the exposure to these
10.1021/jm900364m CCC: $40.75  2009 American Chemical Society
Published on Web 06/03/2009

Amino Alcohol-Based PTH Secretagogues
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13 3983
Scheme 1. Synthesis of Amino Alcohols by Varying the
agents. Depending on the pattern of exposure PTH may act
either as an anabolic agent, thereby building new bone, or as a
catabolic agent, resulting in the loss of bone.19 Prolonged
exposure to PTH results in overall loss of bone as manifested
in conditions such as hyperparathyroidism where PTH levels
are elevated continuously. Alternatively, short intermittent
exposure to elevated PTH or its fragments has an overall bone
forming effect. This has been demonstrated with the daily
subcutaneous administration of teriparatide which reaches Tmax
within 30 min, is rapidly cleared (62 L/h in women and 94 L/h
in men) with a low volume of distribution (0.12 L/kg).20 These
results suggest that an orally active CaR antagonist would also
have to have a pharmacokinetic/pharmacodynamic profile that
is transient in nature in order to have a beneficial bone forming
effect.
Left-Hand Side Moietya
We have reported on the in vitro and in vivo pharmacody-
namic effects of the amino alcohol-based CaR antagonist 38
(NPS 2143, SB-262470-A, Table 1).8,9 When tested in human
embryonic kidney 293 (HEK293) cells stably expressing the
human CaR, analog 38 was potent (IC50 ) 43 nM), it elicited
PTH release from bovine parathyroid cells (EC50 ) 41 nM),
and it increased plasma PTH levels when infused iv in rats. In
the osteopenic ovariectomized (OVX) rat 38 produced sustained
elevations of plasma PTH following oral administration. The
prolonged elevation in PTH levels led to increased bone turnover
with no changes in bone mineral density following five weeks
of treatment. When coadministered with 17ꢀ-estradiol, a known
antiresorptive agent, an increase in bone mass was observed.
In total, these data suggested that a short-acting, orally active
PTH secretagogue may have a net bone forming effect and
would represent a potential new treatment for postmenopausal
osteoporosis.
This manuscript details the characterization of the first
generation amino alcohol-based CaR antagonist hit 2 and some
of the salient structure-activity relationship studies critical to
the optimization of 2 that led to the identification of analog 38.
a Reagents and conditions: (a) LDA, HMPA, i-butyric acid, 4-methoxy
benzylchloride, -78 °C to rt; (b) 3, TEA, acetone, H2O, ethyl chloroformate,
NaN3, 0 °C to rt then toluene 100 °C benzyl alcohol, EtOH, H2, Pd(OH)2;
(c) i-PrOH, 0 °C, epichlorohydrin; (d) NaH, DMF, ROH, 5, 100 °C.
Synthesis Chemistry. A functional assay was developed in
HEK293 cells stably transfected with the human CaR to assess
Hydrogenolysis of the benzyl carbamate with hydrogen/pal-
ladium hydroxide gave (1,1-dimethyl-2-[4-(methyloxy)phenyl]-
ethyl)amine (4). Treatment of amine 4 with epichlorohydrin
provided the intermediate epoxide 5, which was reacted with a
variety of alkoxides to provide a range of left-hand side
substituted analogs (7-17) for profiling against the CaR.
As outlined in Scheme 2, the synthesis of analogs designed
to explore the SAR of the right-hand side aromatic moiety of 2
began with opening of 2-[(phenyloxy)methyl]oxirane (18) with
a variety of different amines. The right-hand side amines
contained within analogs 7, 20, 21, and 22 were designed to
explore the role of the gem-dimethyl group contained within 2.
Alternatively, analogs 23 and 24 were utilized to probe the
optimal distance for the right-hand side aromatic group from
the geminal-dimethyl moiety. Analogs 25 and 26 were incor-
porated in order to understand the potential role of the
p-methoxy moiety and the extension of the π-aromatic system,
respectively.
As outlined in Schemes 3 and 4, analogs 27 and 28 explored
the role of the amino alcohol linker via either oxygen or nitrogen
methylation. Treatment of 11 under standard Borsch reductive
amination conditions (H2CO, NaCNBH3) provided the N-
methylated analog 27 in 91% yield. Methylation of the hydroxyl
moiety of 11 was accomplished by treatment of 11 with sodium
hydride and methyl iodide to provide 28 in 49% yield.
Alternatively, the role of the hydroxyl moiety was explored by
simply removing this group from the amino alcohol antagonist
the ability of test compounds to block extracellular Ca2+-induced
21
increases in intracellular Ca2+
.
A high-throughput screen of
the former SmithKline Beecham compound collection in this
assay format led to the identification of the amino alcohol hit 2
(Figure 1, Table 1). In an effort to optimize the potency and
selectivity of 2, this molecule was divided into three separate
regions to facilitate the systematic study of each of these areas
structure-activity relationships (SAR) (Figure 1). These regions
were the left-hand side benzimidazol-2-one group (designated
A), the amino alcohol linking region and the right-hand-side
aromatic group (designated B). The syntheses utilized to explore
the SAR of each of these individual regions of 2 are detailed in
Schemes 1-6.
The synthesis of the analogs designed to examine the SAR
of the left-hand side aromatic moiety is detailed in Scheme 1.
To facilitate analog synthesis the C2 racemic alcohols were
utilized at this stage as the exact chirality of the C2 asymmetric
center which was required for potent antagonism of the CaR
had not yet been determined. Treatment of iso-butyric acid (3)
with lithium diisopropylamide (LDA), followed by alkylation
with p-methoxybenzyl chloride provided 2,2-dimethyl-3-[4-
(methyloxy)phenyl]propanoic acid (not shown). This acid was
then reacted with ethyl chloroformate, followed by sodium azide.
The intermediate acyl azide was heated (100 °C) to effect
Curtius rearrangement, and the isocyanate was captured with
benzyl alcohol to yield the benzyl carbamate (not shown).

3984 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13
Marquis et al.
Scheme 2. Synthesis of Amino Alcohols by Varying the
antagonist of the CaR in functional and binding assays (Table
1). Compound 2 was identified from a ꢀ-adrenoreceptor
antagonist program where it had been shown to be a potent
antagonist of the ꢀ2-adrenoreceptor and a potent agonist of the
ꢀ1- and ꢀ3-adrenoreceptors. Further selectivity testing of 2
revealed that this basic lipophilic amine, a common pharma-
cophore for a variety of enzymes, also had affinity for the
dopamine (DAT), serotonin (SERT), and norepinephrine (NET)
transporters as well as the cytochrome P450 2D6 (CYP2D6) and
the cardiac human ether-a-go-go related gene (hERG) ion
channel (Table 1).22,23
Right-Hand Side Moietiesa
Structure-Activity Studies. The initial focus of the structure
activity studies was the optimization of CaR antagonist activity
of 2 while also attempting to reduce the affinity of off-target
interactions, most notably those on the ꢀ-adrenoreceptor family
subtypes. Our initial efforts focused on the SAR of the left-
hand side benzimidazol-2-one group as detailed in Table 2.
Replacement of the benzimidazol-2-one moiety of 2 with a
phenyl group provided analog 7, which was 5- and 15-fold more
potent than 2 in the fluorimetric imaging plate reader (FLIPR)
and binding assays, respectively (Table 2). Analog 14, which
incorporates the electron donating 2-methoxyphenyl group,
reduced potency in both assays relative to 7. The left-hand side
alkyl analogs 15-17 were either less potent or equipotent to
the phenyl analog 7 and warranted no further investigation.
Extension of the aromatic moiety of 7 by incorporation of a
2-naphthyl group provided analog 8 with improved potency
versus the lead analog 7. Analogs 9 and 10 with an electron
withdrawing chlorine group at either the 2 or 3 position of the
left-hand side aromatic group resulted in a 4.7- and 2.3-fold
increase in antagonist potency in the FLIPR and binding assays,
respectively, relative to the unsubstituted aromatic analog 7. The
2,3-dichloro aromatic analog 11 resulted in a further increase
in potency over the monochloro analogs 9 and 10, suggesting
that added electron withdrawing capability and increased
lipophilicity results in increased potency. The 2-cyanophenyl
analog 12 was essentially equipotent with the 2,3-dichloro
analog 11. Incorporation of both the chlorine and cyano moieties
provided 13, which was the most potent left-hand side aromatic
identified in these initial SAR studies. However, assessment of
the selectivity of the more potent CaR antagonists 12 and 13
identified during the course of the left-hand side structure-activity
studies revealed that, despite substantial increases in antagonist
potency versus the CaR, no improvement in off-target interac-
tions were made with either of these analogs relative to the initial
screening hit 2 (Table 3).
The structure- activity studies to explore the role of the right-
hand side moiety began with holding the left-hand side phenyl
group as in analog 7 invariant (Table 4). Initial studies probed
the role of the geminal dimethyl group. Removal of the geminal
dimethyl group contained within analog 7 provided 20, which
was inactive in both assays. Moving the geminal dimethyl group
over one carbon provided analog 21, which was also inactive.
Similarly, analog 22 in which one of the methyl groups was
removed was inactive. These results suggest strongly that the
geminal dimethyl moiety contained within this amino alcohol
template is playing a critical role in antagonist potency through
the binding to a hydrophobic pocket within the transmembrane
domain of the receptor and/or by imparting a conformational
constraint to these receptor antagonists through a classic
Thorpe-Ingold effect which serves to increase affinity for the
receptor.24 Indeed, as shown in Figure 2, overlay of the
conformations of global energy minima of analogs 7 and 20
shows clearly that analog 20, lacking the geminal dimethyl
a Reagents and conditions: (a) RNH2, EtOH, 80 °C.
template (Scheme 4). Alkylation of 2,3-dichlorophenol (29) with
1,2-dibromoethane provided the bromide 30 in 13% isolated
yield. Displacement of the bromine with (1,1-dimethyl-2-[4-
(methyloxy)phenyl]ethyl)amine (4) provided analog 31 in 28%
yield.
In an effort to understand the role of the chirality of the C2
hydroxyl moiety as a function of antagonist potency and
selectivty, the racemic alcohol 11 was separated via chiral HPLC
to provide the enantiomerically pure R (faster eluting) and S
(slower eluting) isomers 32 and 33, respectively (Scheme 5).
Assignment of the chirality of each of 32 and 33 was made
possible through the chiral syntheses of each of these enanti-
omers beginning with the alkylation of 2,3-dichlorophenol (29)
with the R- or S-nosyl epoxides to provide intermediates 34
and 35, respectively. Treatment of the epoxides 34 and 35 with
(1,1-dimethyl-2-[4-(methyloxy)phenyl]ethyl)amine (4) effected
regiospecific ring-opening to provide the chiral amino alcohol
antagonists 32 and 33, respectively. Analogs 32 derived from
the R-nosyl epoxide was shown to co-elute with the faster eluting
of the two separated enantiomers, while analog 33 derived from
the S-nosyl epoxide was shown to co-elute with the slower of
the two enantiomers.
The syntheses of antagonists utilized to study the preliminary
SAR studies described above have established some of the better
left- and right-hand side aromatic moieties as well as the
requisite R chirality of the secondary C2-hydroxyl group for
antagonist activity as well as selectivity. In an effort to optimize
antagonist potency each of these groups was incorporated in
the amino alcohol template of the original hit 2. As shown in
Scheme 6, the syntheses of this optimized antagonist began with
alkylation of 2-chloro-6-hydroxybenzonitrile (36) with R-nosyl
epoxide to provide the chiral epoxide 37 with the C2-R
stereochemistry. Regiospecific opening of this chiral epoxide
with (1,1-dimethyl-2-(2-naphthalenyl)ethyl)amine provided an-
tagonist 38.
Results and Discussion
Identification of Screening Hit 2. High-throughput screening
resulted in the identification of the amino alcohol 2 as a weak

Amino Alcohol-Based PTH Secretagogues
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13 3985
Scheme 3. Synthesis of N- and O-Methylated Analogs 27 and 28a
a Reagents and conditions: (a) 37% aq CH2O, NaCNBH3, CH3OH; (b) DMF, NaH, CH3I, rt.
Scheme 4. Synthesis of des-Hydroxy Analog 31a
a Reagents and conditions: (a) K2CO3, 1,3-dibromopropane, 2,3-dichlrorphenol, CH3CN; (b) 30, CH2Cl2, 4.
Scheme 5. Synthesis of Chiral Amino Alcohols 32 and 33a
a Reagents and conditions: (a) HPLC separation; (b) 2,3-dichlorophenol, acetone, K2CO3, (R)-nosyl epoxide, reflux; (c) 2,3-dichlorophenol, acetone,
K2CO3, (S)-nosyl epoxide, reflux; (d) 4, ethanol, reflux.
Scheme 6. Synthesis of Analog 38a
a Reagents and conditions: (a) (R)-nosyl epoxide, acetone, K2CO3, reflux; (b) [1,1-dimethyl-2-(2-naphthalenyl)ethyl]amine, EtOH, reflux.
moiety, is in an extended conformation. In contrast, analog 7,
which contains the geminal dimethyl group, is seen to be in a
C-shaped conformation with a π-π stacking interaction between
the pendant aromatic moieties (distance of 3.9 Å between
aromatic groups for the energy minimized conformation).25
Further modeling analysis revealed that the extended conforma-
tion of analog 20 is approximately 1.6 kcal higher in energy
than the C-shaped conformer, while the extended conformation
of analog 22 is approximately 0.3 kcal lower, further suggesting
that the geminal dimethyl group is playing a critical role in
determining the conformation of analogs such as 7. Removal
of the benzylic methylene group as in analogs 33 resulted in a
complete loss in receptor potency versus analog 7, while addition
of another methylene unit as in analog 24 resulted in a loss in
potency in the FLIPR assay relative to 7 but were essentially
equipotent in the binding assay (Table 4). These data suggest
that it is a combination of the spacing between the two pendant
aromatic groups and the conformational preference imparted
by the geminal dimethyl groups through the Thorpe-Ingold
Table 1. Potencies and Selectivity of the Calcium Receptor Antagonist
Lead 2
assay
conc (µM)
CaR functional IC50
CaR binding IC50
ꢀ2 binding IC50
11.0
31.8
0.0013
0.003
0.007
1.20
0.061
0.600
1.26
ꢀ1 binding EC50
ꢀ3 binding EC50
DAT binding IC50
SERT binding IC50
NET binding IC50
CYP2D6 binding IC50
hERG binding IC50
11.8

3986 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13
Table 2. Potencies of Left-Hand Side Moieties
Marquis et al.
CaR IC50 (µM)
compd
R1
FLIPR
11a
2.3
15.6
16
6.4
2.2
1.4
binding
Figure 2. Overlay of the energy minimized structures of 7 (green)
and 20 (red).
2
7
14
15
16
17
8
31.8
2.3
3.5
7.0
10
phenyl
Table 5. SAR of Propanolamine Linker
2-methoxyphenyl
n-propyl
i-propyl
n-butyl
2-naphthyl
3.2
1.3
9
2-chlorophenyl
3-chlorophenyl
2,3-dichlorophenyl
2-cyanophenyl
2-cyano-3-chlorophenyl
0.49
0.47
0.045
0.058
0.038
1.0
1.0
0.20
0.14
0.070
CaR IC50 (µM)
10
11
12
13
compd
R1
OH
OH
OCH3
H
R2
FLIPR
binding
11
27
28
31
H
CH3
H
0.045
>3.0
>3.0
2.5
0.20
2.3
0.95
0.93
a Functional data.
H
Table 3. Potencies and Selectivity of the Calcium Receptor Antagonist
Hit 2 and Analogs 12 and 13
Table 6. Potencies and Selectivities of the Individual Enantiomers of 11
IC50 or EC50(µM)
assay
2
12
13
CaR FLIPR IC50
CaR binding IC50
ꢀ2 binding IC50
11.0a
31.8
0.0013
0.003
0.007
1.20
0.061
0.600
1.26
0.045
0.20
0.021
NA
0.02
0.30
0.021
0.30
0.036
3.5
0.038
0.070
0.023
NA
NA
1.1
0.034
1.0
0.076
3.6
IC50 (µM)
EC50 (µM)
ꢀ1 binding EC50
compd C2 chirality CaR FLIPR CaR binding ꢀ2 binding ꢀ3 binding
ꢀ3 binding EC50
DAT binding IC50
SERT binding IC50
NET binding IC50
CYP2D6 binding IC50
hERG binding IC50
11
32
33
R/S
R
S
0.045
0.038
0.34
0.20
0.068
0.30
0.021
0.30
0.001
0.20
NAa
0.20
a NA ) not active.
11.8
a Functional data. NA ) not active.
this analog versus the previously discussed off-target interac-
Table 4. Potencies of Right-Hand Side Moieties
tions. Antagonist 26 remained a potent inhibitor of the of the
monoamine transporters (SERT IC50 ) 0.006 µM, NET IC50
0.20 µM, and DAT IC50 ) 0.30 µM) as well as hERG (IC50
)
)
1.0 µM) and CYP2D6 (IC50 ) 0.078 µM). Additionally, no
improvement in selectivity versus the ꢀ-adrenergic receptors
was observed for analog 26 (ꢀ1 and ꢀ3 EC50’s ) 0.023 and 0.65
µM, respectively, and ꢀ2 IC50 ) 0.40 µM).
CaR IC50 (µM)
compd
R1
FLIPR
binding
The structure-activity studies focused on the central pro-
panolamine linker were initiated around analog 11, which was
detailed above as a potent antagonist in both the FLIPR and
binding assays (Table 5). Methylation of either the hydroxyl
group or the secondary amine as in analogs 28 and 27 resulted
in a significant loss in potency, suggesting that hydrogens on
these atoms are critical for the formation of hydrogen bonds
within the receptor active site. Analog 31 in which the hydroxyl
group was removed also resulted in a significant loss in
antagonist potency relative to analog 11, further suggesting the
critical role of this hydroxyl moiety in facilitating effective
interaction with the receptor.
Assessment of the role of the stereochemistry of the C-2
secondary hydroxyl group in determining antagonist potency
and selectivity was performed utilizing analog 11, which as a
racemate is a potent CaR antagonist (Table 6). Upon separation
of the enantiomers it was shown that the C2 R enantiomer 32
was 9- and 4.5-fold more potent than the S enantiomer 33 in
the FLIPR and binding assays, respectively. These results show
that the CaR has a clear stereochemical preference for the R
enantiomer. This stereochemical preference was recapitulated
in vivo in the rat where intravenous injection of the R-
7
C(CH3)2CH2Ph-p-OCH3
(CH2)2Ph-p-OCH3
CH2C(CH3)2Ph-p-OCH3
CH(CH3)CH2Ph-p-OCH3
C(CH3)2Ph-p-OCH3
C(CH3)2(CH2)2Ph-p-OCH3
C(CH3)2CH2Ph
C(CH3)2CH2-2-naphthyl
2.3
2.47
>10
>10
>10
>10
2.78
NTa
0.21
20
21
22
23
24
25
26
>100
>100
>100
>100
13
2.3
0.45
a NT ) not tested.
effect, which permit these aromatic moieties to form a π-π
stacking interaction that are important contributors to antagonist
activity. Removal of the p-methoxy moiety to provide 25
resulted in no loss in activity relative to 7. Analogs 26 with a
2-naphthyl left-hand side amine resulted in an increase in
potency in both assays. Here again, as with the SAR studies
that examined the left-hand side, the SAR studies that investi-
gated the role of the right-hand side of the amino alcohol-based
antagonist template led to improvements in potency over the
parent analog 7 with the incorporation of the 2-naphthyl moiety
as contained within antagonist 26. Unfortunately, this modifica-
tion did not lead to any further increase in the selectivity of

Amino Alcohol-Based PTH Secretagogues
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13 3987
adrenergic receptor for 38 over the screening lead 2. Unfortu-
nately, as with several of the analogs detailed above, no
improvement in selectivity for the monoamine transporters, the
hERG channel, or CYP2D6 were reduced to practice with 38
or any of the other analogs detailed within this manuscript. The
small molecule X-ray crystal structure of 38 (Figure 4) shows
this molecule to have adopted a C-shaped conformation. This
structure further confirms the SAR trends discussed above in
that the geminal dimethyl moiety contained within this amino
alcohol antagonist template serves to impart a conformational
constraint and place the pendant aromatic groups in proximity
for a π-π interaction. This interaction is likely critical for potent
antagonism of the CaR.
Pharmacokinetics and Pharmacodynamics of 38. Evalu-
ation of the pharmacokinetics of amino alcohol 38 in the rat
showed this compound to have an oral bioavailability of 11%
with a high rate of clearance (74 mL/min/kg), a T1/2 of 2 h, and
volume of distribution of 11.0 L/kg. Undoubtedly, the high
volume of distribution of 38 is related to the fact that this
molecule is a basic, lipophilic amine that is widely distributed
into tissues and likely demonstrates lysosomotropic behavior.
As has been previously disclosed and briefly summarized here
for context, the efficacy of analog 38 was evaluated in the
ovariectomized (OVX) rat model of postmenopausal osteoporo-
sis following five weeks of daily oral administration of a 100
µmol/kg dose.9 Additionally, in this experiment, the efficacy
of 38 was compared directly to the efficacy of a subcutaneously
administered dose (5 µg/kg) of rat PTH (1-34). Plasma levels
of analog 38 and PTH following oral administration of 38
remained elevated at the 4 h time point. The high volume of
distribution of 38 is likely responsible for the prolonged
exposure to 38 and the protracted PTH response. In contrast,
while the plasma levels of rat PTH (1-34) achieved a similar
maximum level to that observed for PTH following administra-
tion of 38, baseline levels had been restored after only 2 h. The
differing PTH exposure profiles of orally administered 38 and
injected rat PTH (1-34) had markedly different effects on bone.
Daily oral administration of 38 for 5 weeks resulted in an
increase in both the formation of new bone and the resorption
of old bone with no net increase in bone mass. In contrast,
treatment with rat PTH (1-34) resulted in increased bone mass.
When analog 38 was administered to OVX rats together with
continuous subcutaneous infusion of the antiresorptive agent
17ꢀ-estradiol, a net increase in bone mass was observed.
Figure 3. Acute increases in plasma PTH levels following iv injection
of CaR antagonists 32 or 33 (10 µmol/kg) in normal conscious rats.
Values are mean ( SE, n ) 6/group. PTH was measured using a rat
PTH(1-34) immunoradiometric assay (Immutopics, San Clemente, CA),
Note the greater activity of 32 (R-enantiomer) compared with 33 (S-
enantiomer).
enantiomer elicited significantly higher levels of PTH over that
of the less active S-enantiomer (Figure 3). Evaluation of the
ꢀ-adrenoreceptor selectivity of the individual R and S enanti-
omers showed that the S enantiomer 33 was 300-fold more
potent than the R enantiomer 32 as a ꢀ2 adrenoreceptor
antagonist. Additionally when evaluated as ꢀ3 adrenoreceptor
agonists, the R enantiomer 32 was devoid of activity while the
S enantiomer 33 was active (Table 6). If one assumes that the
three-point binding model detailed in the Easson-Stedman
hypothesis extends to aryloxyethyl amines such as 32 and 33,
then this stereochemical preference for adrenoreceptor activity
is consistent with the plethora of available adrenoreceptor
antagonist/agonist literature.26 It was also encouraging to observe
that the stereochemical preference exerted by the CaR upon the
amino alcohol antagonist template was opposite to that preferred
by the ꢀ-adrenergic receptors examined. It is this stereochemical
preference that has permitted the disassociation of CaR antago-
nist activity from ꢀ-adrenergic receptor activity present in the
initial lead 2. Unfortunately this stereochemical preference,
which led to greater CaR potency and selectivity over the
ꢀ-adrenergic receptor, did not extend further to selectivity over
the monoamine transporters for analog 32 (SERT IC50 ) 0.027
µM, NET IC50 ) 0.07 µM, and DAT IC50 ) 1.3 µM) as well
as hERG (IC50 ) 2.6 µM) and CYP2D6 (IC50 ) 0.005 µM).
As detailed above and outlined in Scheme 7, an initial
understanding of the structure-activity relationships that exist
within the three regions of the amino alcohol antagonist lead 2
led to the identification of the optimal left-hand side aromatic
group contained within 13 and the right-hand side aromatic
amine within 26 as well as the requisite R stereochemistry of
the secondary alcohol of the propanolamine linker in 34. In an
effort to further optimize antagonist activity, the critical binding
elements contained within 13, 26, and 34 were combined to
produce analog 38, which retained potent CaR antagonism.
These potencies represent a 255- and 10600-fold increases in
antagonist potency for 38 over the lead 2 in the FLIPR and
binding assays, respectively (Table 7). Also encouraging was
the separation of ꢀ-adrenergic receptor activity from CaR
antagonist activity with analog 38, where it was shown to be a
4.3 µM antagonist of the ꢀ2 adrenergic receptor and was devoid
of agonist activity at the ꢀ1 or ꢀ3 adrenergic receptors. This
represents a 3300-fold improvement in selectivity at the ꢀ2
Conclusions
In this paper, we have detailed the identification of the high
throughput screening lead 2 as a weak antagonist of the CaR
with a variety of off-target interactions. Structure-activity
studies to optimize the three different portions of this amino
alcohol lead in terms of both potency versus the CaR as well
as off-target selectivity led to the discovery that the R-
enantiomer of the C2 alcohol of the propanolamine linker
conferred greater CaR antagonist activity with greater selectivity
over the ꢀ-adrenergic receptor than that of the S-enantiomer
but did not affect activity in other selectivity counterscreens,
most notably the norepinephrine, dopamine, and serotonin
monoamine transporters, the hERG ion channel and CYP2D6,
all of which share an affinity for lipophilic basic amines. Further
optimization efforts led to the identification of analog 38, a
potent CaR antagonist with high clearance, a large volume of
distribution, and low oral bioavailability in rats. Analog 38 has
been shown to increase bone mass in OVX rats when given in
conjunction with the antiresorptive agent 17ꢀ-estradiol. To

3988 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13
Table 7. Potencies and Selectivities of 2 and 38
Marquis et al.
IC50 (µM)
EC50 (µM)
compd
CaR FLIPR
CaR binding
SERT binding
NET binding
DAT binding
CYP2D6
hERG binding
ꢀ2 binding
ꢀ1/ꢀ3 binding
2
38
11.0
0.043
31.8
0.003
0.061
0.002
0.60
0.20
1.20
0.20
1.26
0.045
11.8
3.00
0.0013
4.3
0.003/0.007
NA/NAa
a NA ) not active.
The CaR assay began when the cell media was aspirated from
the cell plate using a Tecan plate washer, leaving nothing but the
cell monolayer. Dye load buffer is added to the cell plate at 20
µL/well using a multidrop, and the loaded plate was incubated for
45 min at 37 °C, 5% CO2. Compound plates were received with 1
µL of compound stamped at 5 mM top concentration (25 µM final
conc in cell plate). Compound dilution buffer was added to columns
1-24 in the compound plate at 65 µL/well using a Multidrop.
Column 6 was prestamped with 1 µL of DMSO to represent the
high control, and column 18 received 65 µL of buffer as the low
control. The compound addition takes place on a Cybi Well
dispenser when 10 µL of diluted compound was added to the dye
loaded cell plate. The cell plate with compound was then incubated
at room temperature for 5 min.. The antagonist addition took place
on the FLIPR when 10 µL of EC80 challenge was added to the cell
plate and fluorescence imagining proceeded for 65 s. Column 18
of the EC80 challenge plate contained only buffer to represent a
low control or tool antagonist.
Calcium Receptor Binding Assay. HEK 293 4.0-7 cells stably
transfected with the human parathyroid calcium receptor
(“HuPCaR”) were scaled up in T180 tissue culture flasks. Plasma
membrane is obtained by polytron homogenization or glass dounc-
ing in buffer (50 mM Tris-HCl pH 7.4, 1 mM EDTA, 3 mM MgCl2)
in the presence of a protease inhibitor cocktail containing 1 µM
leupeptin, 0.04 µM pepstatin, and 1 mM PMSF. Aliquoted
membrane was snap frozen and stored at -80 °C. 3H labeled
compound was radiolabeled to a radiospecific activity of 44 Ci/
mmol and was aliquoted and stored in liquid nitrogen for radio-
chemical stability.
A typical reaction mixture contained 2 nM 3H compound ((R,R)-
N-4′-methoxy-t-3-3′-methyl-1′-ethylphenyl-1-(1-naphthyl)ethy-
lamine), or 3H compound (R)-N-[2-hydroxy-3-(3-chloro-2-cyanophe-
noxy)propyl]-1,1-dimethyl-2-(4-methoxyphenyl)ethylamine 4-10
µg membrane in homogenization buffer containing 0.1% gelatin
and 10% EtOH in a reaction volume of 0.5 mL. Incubation was
performed in 12 × 75 polyethylene tubes in an ice water bath. To
each tube, 25 µL of test sample in 100% EtOH was added, followed
by 400 µL of cold incubation buffer and 25 µL of 40 nM
3H-compound in 100% EtOH for a final concentration of 2 nM.
The binding reaction was initiated by the addition of 50 µL of
80-200 ug/mL HEK 293 4.0-7 membrane diluted in incubation
buffer and allowed to incubate at 4 °C for 30 min. Wash buffer
was 50 mM Tris-HCl containing 0.1% PEI. Nonspecific binding
was determined by the addition of 100-fold excess of unlabeled
homologous ligand and was generally 20% of total binding. The
binding reaction was terminated by rapid filtration onto 1% PEI
pretreated GF/C filters using a Brandel harvester. Filters were placed
in scintillation fluid and radioactivity assessed by liquid scintillation
counting.
Figure 4. Small molecule X-ray crystal structure of the calcium
receptor antagonist 38.
facilitate new bone growth, the ideal molecule should produce
a transient spike of PTH release following oral administration.
Efforts to design molecules with this desired pharmacokinetic
and pharmacodynamic profile and greater selectivity over the
hERG ion channel, monoamine transporters, and CYP2D6 will
be the subject of future publications.
Experimental Procedures
Calcium Receptor Inhibitor Assay. HEK 293 4.0-7 cells were
constructed as described by Rogers et al.27 First, 48 h prior to
running the CaR assay, frozen HEK293 CaRec4.0-c17 cells were
thawed, counted, and diluted to 3 × 105/mL (15K/50 µL). The cell
medium used to dilute the cells consisted of DMEM/F12 (HAM’S)
1:1 with L-glutamine, 15 mM HEPES, phenol red, 10% fetal bovine
serum, and 1% penicillin-streptomycin solution. Cell solution was
seeded at 15K cells/50 µL/well in Greiner poly-D-lysine coated 384-
well, black, clear bottom, tissue culture plates and left at room
temperature for 1 h to reduce edge effect. After the first hour at
room temperature, cell plates were then placed into a 37 °C, 5%
CO2 incubator for 48 h.
On the day of the experiment, plate confluency was first checked
by microscope. Wells should be ∼100% confluent in an even cell
monolayer. Assay reagents were prepared fresh. Dye load buffer
consisted of Hank’s buffered saline solution with 0.75 mM calcium,
without magnesium, without sodium bicarbonate, with 20 mM
Hepes, probenecid (2.5 mM final concentration), Fluo4 (2 µM final
concentration), and brilliant black (500 µM final concentration).
Compound dilution buffer consisted of Hank’s buffered saline
solution without calcium, without magnesium (without sodium
bicarbonate), and CHAPS (0.01% final concentration). A ligand
curve plate was also prepared fresh. A 16 point curve was dispensed
into a Greiner 384-well polypropylene plate. The top concentration
of the ligand CaCl was 2.875 mM (final concentration), and the
lowest concentration was 0.375 mM (final concentration). An EC80
value was generated from the curve data.
General. Except where indicated, materials and reagents were
used as supplied. Nuclear magnetic resonance spectra were recorded
at either 250 or 400 MHz using, respectively, a Bruker AM 250 or
Bruker AC 400 spectrometer. Mass spectra were taken on a PE
Syx API III instruments using electrospray (ES) ionization tech-
niques. Elemental analyses were obtained using a Perkin-Elmer
240C elemental analyzer. Reactions were monitored by TLC
analysis using Analtech Silica Gel GF or E. Merck Silica Gel 60

Amino Alcohol-Based PTH Secretagogues
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13 3989
Scheme 7. Combination of the SAR Studies Leading to Analog 38
F-254 thin layer plates. Flash chromatography was carried out on
E. Merck Kieselgel 60 (230-400 mesh) silica gel. The purity of
all tested compounds, which were not analyzed via elemental
analysis, were determined by high performance liquid chromatog-
raphy. Method A: 5-100% acetonitrile:water (with 0.1% TFA) over
18 min with a total run time of 20 min using a 4.6 mm × 50 mm
id S-5 mm, YMC Combiscreen ODS column. Method B: 5-100%
acetonitrile:water (with 0.1% TFA) over 18 min with a total run
time of 20 min using a 4.6 mm × 150 mm id, 5 mm, Zorbax
Stablebond C8 column. All compounds analyzed by these methods
possessed purities equal to or greater than 95%, with the exception
of analog 14, which is 91.7% pure by method A and 95.8% pure
by method B.
(1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)(2-oxiranylme-
thyl)amine (5). A solution of (1,1-dimethyl-2-[4-(methyloxy)phe-
nyl]ethyl)amine (7.46 g, 41.6 mmol) in isopropyl alcohol (75 mL)
was cooled to 0 °C under N2. Epichlorohydrin (3.2 mL, 40.8 mmol)
was added dropwise and reaction stirred at 0 °C for 30 min before
warming to room temperature overnight. The reaction was con-
centrated in vacuo and purified via column chromatography
(0-12% CH3OH/CH2Cl2) to provide the title compound (45%).
1H NMR (400 MHz, chloroform-d) δ ppm 7.08-7.16 (m, J ) 6.25,
6.25, 5.81, 3.92 Hz, 2 H), 6.87 (s, 1 H), 6.82-6.86 (m, 2 H), 3.98
(ddd, J ) 11.05, 8.15, 5.31 Hz, 1 H), 3.76-3.83 (m, 3 H), 3.67
(dd, J ) 6.32, 4.04 Hz, 1 H), 3.56-3.65 (m, J ) 11.24, 9.16, 9.16,
5.31 Hz, 2 H), 2.98 (dd, J ) 12.13, 3.79 Hz, 1 H), 2.76-2.82 (m,
1 H), 2.75 (s, 1 H), 1.12-1.20 (m, 6 H).
4.42, 4.42 Hz, 1 H), 7.14 (t, J ) 8.84 Hz, 2 H), 6.90 (d, J ) 8.84
Hz, 2 H), 6.00 (d, J ) 4.04 Hz, 1 H), 4.30-4.39 (m, 1 H), 4.18 (t,
J ) 7.71 Hz, 2 H), 3.73 (s, 3 H), 3.31 (s, 1 H), 3.11 (d, J ) 9.60
Hz, 1 H), 2.92-3.01 (m, 2 H), 1.17-1.26 (m, 6 H). MS (ESI)
380.2 (M + H)+.
1-[(2-Chlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(methyloxy)phe-
nyl]ethyl)amino)-2-propanol (9). The title compound was prepared
following the procedure above substituting 2-chlorophenol for
phenol. The title compound (29%) was isolated as a white solid:
1H NMR (400 MHz, DMSO-d6) δ ppm 8.93 (s, 1 H), 8.65 (s, 1
H), 7.45 (dd, J ) 7.96, 1.64 Hz, 1 H), 7.28-7.38 (m, 1 H),
7.13-7.24 (m, 3 H), 6.99 (td, J ) 7.71, 1.26 Hz, 1 H), 6.90 (d, J
) 8.84 Hz, 2 H), 5.97 (d, J ) 4.29 Hz, 1 H), 4.28 (s, 1 H),
4.08-4.19 (m, 2 H), 3.74 (s, 3 H), 3.32 (d, J ) 2.78 Hz, 1 H),
3.12 (d, J ) 9.60 Hz, 1 H), 2.89-2.98 (m, 2 H), 1.16-1.25 (m, 6
H). MS (ESI) 364.2 (M + H)+.
1-[(3-Chlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(methyloxy)phe-
nyl]ethyl)amino)-2-propanol (10). The title compound was pre-
pared following the procedure above substituting 3-chlorophenol
for phenol. The title compound (19%) was isolated as a white solid.
1H NMR (400 MHz, DMSO-d6) δ ppm 8.97 (s, 1 H), 8.59 (s, 1
H), 7.31-7.38 (m, 1 H), 7.15 (d, J ) 8.59 Hz, 2 H), 7.06-7.11
(m, 1 H), 7.03 (dd, J ) 7.96, 1.14 Hz, 1 H), 6.88-6.99 (m, 3 H),
5.94 (d, J ) 4.29 Hz, 1 H), 4.23 (s, 1 H), 4.02-4.10 (m, 2 H),
3.74 (s, 3 H), 3.26 (s, 1 H), 3.05 (d, J ) 9.09 Hz, 1 H), 2.89-2.98
(m, 2 H), 1.16-1.24 (m, 6 H). MS (ESI) 364.2 (M + H)+.
1-[(2,3-Dichlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(methyloxy)-
phenyl]ethyl)amino)-2-propanol (11). The title compound was
prepared following the procedure above substituting 2,3-dichlo-
rophenol for phenol. The title compound (26%) was isolated as a
white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.93 (s, 1 H),
8.66 (s, 1 H), 7.32-7.40 (m, 1 H), 7.23 (ddd, J ) 17.43, 8.34,
1.26 Hz, 2 H), 7.15 (d, J ) 8.59 Hz, 2 H), 6.90 (d, J ) 8.84 Hz,
2 H), 5.99 (d, J ) 4.80 Hz, 1 H), 4.25-4.32 (m, 1 H), 4.13-4.23
(m, J ) 11.21, 11.21, 10.17, 5.05 Hz, 2 H), 3.74 (s, 3 H), 3.29 (s,
1 H), 3.11 (d, J ) 9.60 Hz, 1 H), 2.90-2.98 (m, 2 H), 1.16-1.24
(m, 6 H). MS (ESI) 398.0/400.0 [(M/M + 2) + H]+.
2-([3-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-2-
hydroxypropyl]oxy)benzonitrile (12). The title compound was
prepared following the procedure above substituting 2-[4-(methy-
loxy)phenyl]-2-propanamine for 2-[4-(methyloxy)phenyl]etha-
namine and 2-[(2-oxiranylmethyl)oxy]benzonitrile for 2-[(pheny-
loxy)methyl]oxirane. The title compound (82%) was isolated as
an off white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm
8.92-9.16 (m, 1 H), 8.71 (br s, 1 H), 7.64-7.81 (m, 2 H), 7.32 (d,
J ) 8.59 Hz, 1 H), 7.02-7.25 (m, 3 H), 6.90 (d, J ) 8.84 Hz, 2
H), 6.02 (br s, 1 H), 4.11-4.39 (m, 2 H), 3.59-3.83 (m, 2 H),
3.25-3.50 (m, 4 H), 3.13 (q, J ) 9.18 Hz, 1 H), 2.81-3.03 (m, 1
H), 1.22 (s, 6 H). MS (ESI) 355.2 (M + H)+.
1-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-(phe-
nyloxy)-2-propanol (7). A solution of sodium hydride (95%, 0.116
g, 4.59 mmol) in DMF (6.0 mL) under N2 was prepared. Phenol
(0.433 g, 4.60 mmol) in DMF (6.0 mL) was added and the reaction
stirred at room temperature for 15 min (1,1-dimethyl-2-[4-(methy-
loxy)phenyl]ethyl)(2-oxiranylmethyl)amine (0.354 g, 1.51 mmol)
in DMF (4.0 mL) was added and the reaction heated at 100 °C for
20 h. The reaction was cooled and quenched with the addition of
H2O. The aqueous layer was extracted two times with ethyl acetate.
The combined organic layers were washed with brine, dried over
Na2SO4, filtered, and concentrated. Column chromatography (0-10%
CH3OH/CH2Cl2) was used to purify. The resulting oil was dissolved
in CH3CN and HCl/Et2O (1.0 N, 1.5 equiv) was added. The reaction
stirred for 10-15 min and concentrated in vacuo to afford the HCl
1
salt of the title compound (38%) as a white solid. H NMR (400
MHz, DMSO-d6) δ ppm 9.01 (s, 1 H), 8.60 (s, 1 H), 7.32 (dd, J )
8.97, 7.20 Hz, 2 H), 7.14 (t, J ) 7.96 Hz, 2 H), 6.97 (t, J ) 7.96
Hz, 3 H), 6.90 (d, J ) 8.59 Hz, 2 H), 5.93 (d, J ) 4.04 Hz, 1 H),
4.24 (s, 1 H), 4.03 (d, J ) 5.31 Hz, 2 H), 3.74 (s, 3 H), 3.23 (s, 1
H), 3.06 (d, J ) 9.60 Hz, 1 H), 2.90-2.99 (m, 2 H), 1.16-1.24
(m, 6 H). MS (ESI) 330.2 (M + H)+.
1-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-(2-
naphthalenyloxy)-2-propanol (8). The title compound was pre-
pared following the procedure above substituting 2-naphthol for
phenol. The title compound (21%) was isolated as a white solid.
1H NMR (400 MHz, DMSO-d6) δ ppm 9.05 (s, 1 H), 8.64 (s, 1
H), 7.85 (ddd, J ) 9.98, 6.69, 5.56 Hz, 3 H), 7.44-7.51 (m, 1 H),
7.37 (td, J ) 7.45, 1.01 Hz, 2 H), 7.20-7.25 (m, J ) 4.42, 4.42,
2-Chloro-6-([3-((1,1-dimethyl-2-[4-(methyloxy)phenyl]ethyl)-
amino)-2-hydroxypropyl]oxy)benzonitrile (13). The title com-
pound was prepared following the procedure above substituting
2-cyano-3-chlorophenol for phenol. The title compound (19%) was
1
isolated as a white solid. H NMR (400 MHz, DMSO-d6) δ ppm
9.04 (s, 1 H), 8.72 (s, 1 H), 7.71 (t, J ) 8.34 Hz, 1 H), 7.38 (s, 1

3990 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13
Marquis et al.
H), 7.32 (dd, J ) 8.34, 3.28 Hz, 1 H), 7.13 (d, J ) 4.04 Hz, 2 H),
6.90 (d, J ) 8.84 Hz, 2 H), 6.05 (s, 1 H), 4.29 (td, J ) 10.23, 3.79
Hz, 3 H), 3.74 (s, 3 H), 3.29 (s, 1 H), 3.13 (s, 1 H), 2.90-2.99 (m,
2 H), 1.16-1.25 (m, 6 H). MS (ESI) 389.0 (M + H)+.
5.05 Hz, 1 H), 4.24 (ddd, J ) 8.91, 4.36, 4.17 Hz, 1 H), 3.98 (quin,
J ) 4.74 Hz, 2 H), 3.73 (s, 3 H), 3.15 (t, J ) 11.62 Hz, 2 H), 3.19
(d, J ) 19.96 Hz, 1 H), 3.05 (d, J ) 9.85 Hz, 1 H), 2.90-2.98 (m,
J ) 11.64, 6.32, 5.23, 4.61, 4.04 Hz, 2 H). MS (ESI) 302.2
(M + H)+.
1-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-([2-
(methyloxy)phenyl]oxy)-2-propanol (14). The title compound was
prepared following the procedure above substituting guaiacol for
phenol. The title compound (20%) was isolated as a white solid.
1H NMR (400 MHz, DMSO-d6) δ ppm 8.92 (s, 1 H), 8.59 (s, 1
H), 7.13 (d, J ) 6.82 Hz, 2 H), 6.98-7.05 (m, J ) 10.24, 3.69,
3.56, 3.56, 3.45, 1.52 Hz, 2 H), 6.87-6.96 (m, J ) 14.27, 7.71,
7.33, 4.04 Hz, 4 H), 5.91 (s, 1 H), 4.19-4.27 (m, 1 H), 3.96-4.07
(m, 2 H), 3.71-3.79 (m, 6 H), 3.27 (d, J ) 10.11 Hz, 1 H), 3.07
(d, J ) 9.60 Hz, 1 H), 2.89-2.98 (m, 2 H), 1.15-1.25 (m, 6 H).
MS (ESI) 360.2 (M + H)+.
1-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-(pro-
pyloxy)-2-propanol (15). The title compound was prepared fol-
lowing the procedure above substituting n-propanol for phenol. The
title compound (19%) was isolated as a white solid. 1H NMR (400
MHz, DMSO-d6) δ ppm 8.85 (s, 1 H), 8.45 (s, 1 H), 7.09-7.17
(m, 2 H), 6.90 (d, J ) 8.84 Hz, 2 H), 5.64 (s, 1 H), 3.99 (ddd, J )
10.61, 6.82, 5.81 Hz, 1 H), 3.74 (s, 3 H), 3.45 (d, J ) 5.31 Hz, 1
H), 3.43 (d, J ) 5.05 Hz, 1 H), 3.33 (m, 1 H), 3.11 (d, J ) 2.78
Hz, 1 H), 3.08 (s, 1 H), 2.85-2.95 (m, 3 H), 1.47-1.56 (m, J )
7.20, 7.04, 7.04, 7.04, 7.04 Hz, 2 H), 1.15-1.21 (m, 6 H), 0.87 (t,
J ) 7.33 Hz, 3 H). MS (ESI) 296.2 (M + H)+.
1-((1,1-Dimethyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-[(1-
methylethyl)oxy]-2-propanol (16). The title compound was pre-
pared following the procedure above substituting isopropyl alcohol
for phenol. The title compound (29%) was isolated as a white solid.
1H NMR (400 MHz, DMSO-d6) δ ppm 8.96 (s, 1 H), 8.49 (s, 1
H), 7.11-7.19 (m, 2 H), 6.90 (d, J ) 8.59 Hz, 2 H), 5.61 (s, 1 H),
3.92-4.02 (m, 1 H), 3.71-3.77 (m, 3 H), 3.58 (dt, J ) 12.13,
6.06 Hz, 1 H), 3.42-3.46 (m, 1 H), 3.33-3.40 (m, 1 H), 3.10 (t,
J ) 10.99 Hz, 1 H), 2.96 (s, 1 H), 2.84-2.94 (m, J ) 9.22, 9.22,
7.71, 7.20 Hz, 2 H), 1.15-1.21 (m, 6 H), 1.09 (t, J ) 6.57 Hz, 6
H). MS (ESI) 296.2 (M + H)+.
1-(Butyloxy)-3-((1,1-dimethyl-2-[4-(methyloxy)phenyl]ethyl)-
amino)-2-propanol (17). The title compound was prepared fol-
lowing the procedure above substituting n-butanol for phenol. The
title compound (29%) was isolated as a white solid. 1H NMR (400
MHz, DMSO-d6) δ ppm 9.04 (s, 1 H), 8.53 (s, 1 H), 7.11-7.19
(m, 2 H), 6.90 (d, J ) 8.84 Hz, 2 H), 3.97-4.06 (m, J ) 6.47,
6.47, 6.19, 5.62, 4.80 Hz, 1 H), 3.67-3.76 (m, 3 H), 3.47-3.58
(m, 2 H), 3.39 (ddd, J ) 7.07, 3.92, 3.66 Hz, 1 H), 3.35 (d, J )
6.06 Hz, 1 H), 3.09 (t, J ) 10.99 Hz, 1 H), 2.85-2.97 (m, J )
13.55, 8.46, 7.01, 6.85 Hz, 3 H), 1.49 (td, J ) 10.67, 6.69 Hz, 2
H), 1.33 (ddd, J ) 19.58, 12.76, 4.55 Hz, 3 H), 1.15-1.24 (m, 6
H), 0.89 (t, J ) 7.33 Hz, 3 H). MS (ESI) 310.2 (M + H)+.
2-[(Phenyloxy)methyl]oxirane (18). Potassium carbonate (15.1
g, 109 mmol) and epichlorohydrin (21 mL, 268 mmol) were added
to a solution of phenol (5.05 g, 53.7 mmol) and CH3CN. The flask
was sealed and heated at reflux for 3 days. The reaction was cooled
to room temperature, filtered, washed with ethyl acetate, and
concentrated. Column chromatography (0-30% ethyl acetate:
hexane) provided 6.08 g (76%) of 18 as an oil. 1H NMR (400 MHz,
chloroform-d) δ ppm 7.32 (dd, J ) 8.84, 7.33 Hz, 1 H), 7.28 (s, 1
H), 6.92-7.03 (m, 3 H), 4.24 (dd, J ) 10.86, 3.28 Hz, 1 H), 3.99
(dd, J ) 10.99, 5.68 Hz, 1 H), 3.33-3.45 (m, J ) 6.09, 3.66, 2.95,
2.95 Hz, 1 H), 2.93 (d, J ) 4.29 Hz, 1 H), 2.79 (dd, J ) 4.93, 2.65
Hz, 1 H).
1-((2-Methyl-2-[4-(methyloxy)phenyl]propyl)amino)-3-(phe-
nyloxy)-2-propanol (21). The title compound was prepared fol-
lowing the procedure above substituting 2-methyl-2-[4-(methyloxy)-
phenyl]-1-propanamine for 2-[4-(methyloxy)phenyl]ethanamine.
The title compound (50%) was isolated as a white solid. 1H NMR
(400 MHz, DMSO-d6) δ ppm 8.43 (br s, 2 H), 7.37 (d, J ) 8.84
Hz, 2 H), 7.30 (dd, J ) 8.59, 7.33 Hz, 2 H), 6.92 (d, J ) 8.59 Hz,
4 H), 6.87-6.98 (m, 1 H), 5.91 (d, J ) 4.80 Hz, 1 H), 4.27 (d, J
) 3.28 Hz, 1 H), 3.86-3.99 (m, J ) 10.11, 8.91, 8.91, 5.18 Hz, 2
H), 3.74 (s, 3 H), 3.25 (br s, 2 H), 3.10 (br s, 1 H), 2.95 (t, J )
10.99 Hz, 1 H), 1.41 (s, 6 H). MS (ESI) 330.2 (M + H)+.
1-((1-Methyl-2-[4-(methyloxy)phenyl]ethyl)amino)-3-(pheny-
loxy)-2-propanol (22). The title compound was prepared following
the procedure above substituting 1-[4-(methyloxy)phenyl]-2-pro-
panamine for 2-[4-(methyloxy)phenyl]ethanamine. The title com-
1
pound (20%) was isolated as a white solid. H NMR (400 MHz,
DMSO-d6) δ ppm 9.13 (br s, 1 H), 8.76 (br s, 1 H), 7.31 (dd, J )
8.59, 7.33 Hz, 2 H), 7.17 (d, J ) 7.58 Hz, 2 H), 6.87-7.00 (m, 6
H), 5.94 (br s, 1 H), 4.27 (d, J ) 4.29 Hz, 1 H), 4.00 (d, J ) 4.80
Hz, 2 H), 3.94-4.06 (m, 1 H), 3.73 (s, 3 H), 3.41 (d, J ) 10.11
Hz, 2 H), 3.37 (br s, 2 H), 3.28 (br s, 1 H), 3.22 (ddd, J ) 8.91,
4.11, 3.41 Hz, 2 H), 3.11 (br s, 1 H), 3.08 (d, J ) 9.35 Hz, 1 H),
2.61 (dddd, J ) 10.52, 5.31, 4.04, 3.63 Hz, 1 H), 1.12 (t, J ) 6.69
Hz, 3 H). MS (ESI) 316.2 (M + H)+.
1-((1-Methyl-1-[4-(methyloxy)phenyl]ethyl)amino)-3-(pheny-
loxy)-2-propanol (23). The title compound was prepared following
the procedure above substituting 2-[4-(methyloxy)phenyl]-2-pro-
panamine for 2-[4-(methyloxy)phenyl]ethanamine. The title com-
1
pound (66%) was isolated as a white solid. H NMR (400 MHz,
DMSO-d6) δ ppm 9.51 (br s, 1 H), 9.10 (br s, 1 H), 7.59 (m, J )
8.84 Hz, 2 H), 7.27 (dd, J ) 8.59, 7.33 Hz, 2 H), 6.99 (m, J )
8.84 Hz, 2 H), 6.93 (t, J ) 7.33 Hz, 1 H), 6.86 (d, J ) 7.83 Hz, 2
H), 5.82 (d, J ) 4.80 Hz, 1 H), 4.14 (td, J ) 6.63, 3.16 Hz, 1 H),
3.84-3.95 (m, J ) 5.34, 5.34, 5.12, 4.67 Hz, 2 H), 3.77 (s, 3 H),
2.77 (t, J ) 10.74 Hz, 1 H), 2.51-2.63 (m, 1 H), 1.73 (d, J ) 2.02
Hz, 6 H). MS (ESI) 316.2 (M + H)+.
1-((1,1-Dimethyl-3-[4-(methyloxy)phenyl]propyl)amino)-3-
(phenyloxy)-2-propanol (24). The title compound was prepared
following the procedure above substituting 2-methyl-4-[4-(methy-
loxy)phenyl]-2-butanamine for 2-[4-(methyloxy)phenyl]ethanamine.
The title compound (58%) was isolated as a white solid. 1H NMR
(400 MHz, DMSO-d6) δ ppm 9.00 (br s, 1 H), 8.57 (br s, 1 H),
7.31 (dd, J ) 8.72, 7.20 Hz, 2 H), 7.15 (m, J ) 8.59 Hz, 2 H),
6.97 (d, J ) 7.07 Hz, 3 H), 6.86 (m, 2 H), 5.90 (d, J ) 4.80 Hz,
1 H), 4.16-4.28 (m, 1 H), 4.02 (d, J ) 5.56 Hz, 2 H), 3.72 (s, 3
H), 3.11-3.24 (m, 1 H), 2.97 (d, J ) 9.60 Hz, 1 H), 2.56 (ddd, J
) 7.71, 5.18, 4.29 Hz, 2 H), 1.88 (ddd, J ) 7.52, 5.56, 4.36 Hz, 2
H), 1.37 (s, 6 H). MS (ESI) 344.2 (M + H)+.
1-([1,1-Dimethyl-2-(2-naphthalenyl)ethyl]amino)-3-(phenyloxy)-
2-propanol (26). The title compound was prepared following the
procedure above substituting 2-methyl-1-(2-naphthalenyl)-2-pro-
panamine for 2-[4-(methyloxy)phenyl]ethanamine. The title com-
1
pound (57%) was isolated as a white solid. H NMR (400 MHz,
DMSO-d6) δ ppm 9.16 (br s, 1 H), 8.73 (br s, 1 H), 7.90 (t, J )
3.92 Hz, 2 H), 7.88 (s, 1 H), 7.78 (s, 1 H), 7.46-7.56 (m, J )
6.38, 4.83, 4.06, 4.06, 3.41, 2.02 Hz, 2 H), 7.40 (dd, J ) 8.34,
1.52 Hz, 1 H), 7.24-7.37 (m, 2 H), 6.98 (t, J ) 4.17 Hz, 2 H),
6.92-7.03 (m, 1 H), 5.96 (d, J ) 4.80 Hz, 1 H), 4.29 (d, J ) 3.79
Hz, 1 H), 4.05 (d, J ) 5.31 Hz, 2 H), 3.30 (br s, 1 H), 3.21 (d, J
) 2.02 Hz, 2 H), 3.12 (d, J ) 9.60 Hz, 1 H), 1.30 (s, 6 H). MS
(ESI) 350.2 (M + H)+.
1-[(2,3-Dichlorophenyl)oxy]-3-[(1,1-dimethyl-2-[4-(methyloxy)-
phenyl]ethyl)(methyl)amino]-2-propanol (27). Formaldehyde (37%
aq, 1.8 mL, 22.2 mmol) and NaCNBH3 (0.360 g, 5.73 mmol) were
added to a solution of 1-[(2,3-dichlorophenyl)oxy]-3-((1,1-dimethyl-
2-[4-(methyloxy)phenyl]ethyl)amino)-2-propanol (11, 0.580 g, 1.46
1-((2-[4-(Methyloxy)phenyl]ethyl)amino)-3-(phenyloxy)-2-
propanol (20). 2-[(Phenyloxy)methyl]oxirane (18) (0.639 g, 4.26
mmol) in ethanol (8.5 mL) was added to 2-[4-(methyloxy)phe-
nyl]ethanamine (0.640 g, 4.23 mmol) and the reaction heated at
80 °C in a sealed flask for 20 h. The reaction was cooled to room
temperature and concentrated in vacuo. Column chromatography
(0-10% CH3OH:CH2Cl2) produced 0.563 g (39%) of 20 as an off-
1
white solid. H NMR (400 MHz, DMSO-d6) δ ppm 9.11 (br s, 1
H), 8.90 (br s, 1 H), 7.30 (d, J ) 8.08 Hz, 1 H), 7.24-7.37 (m, 1
H), 7.18 (d, J ) 8.59 Hz, 2 H), 6.87-6.99 (m, 5 H), 5.92 (d, J )

Amino Alcohol-Based PTH Secretagogues
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13 3991
mmol) in CH3OH (15 mL) under N2. The reaction was stirred at
room temperature for 5 days. Dilution with H2O was followed by
extraction with CH2Cl2 two times. The combined organic layers
were washed with brine, dried over Na2SO4, filtered, and concen-
trated. Column chromatography (0-10% CH3OH:CH2Cl2) followed
by evaporation of solvent in the presence of HCl (1.0 M in Et2O)
produced 0.592 g (91%) of 27 as a white solid. 1H NMR (400 MHz,
DMSO-d6) δ ppm 9.44 (br s, 1 H), 7.36 (t, J ) 8.21 Hz, 1 H), 7.23
(dd, J ) 14.27, 8.46 Hz, 2 H), 7.19 (d, J ) 8.34 Hz, 2 H), 6.91 (d,
J ) 8.59 Hz, 2 H), 6.08 (d, J ) 3.79 Hz, 1 H), 5.97 (br s, 1 H),
4.38 (q, J ) 7.07 Hz, 1 H), 4.23 (s, 1 H), 4.20 (q, J ) 5.39 Hz, 2
H), 3.74 (s, 3 H), 3.67 (br s, 1 H), 3.61 (br s, 1 H), 3.02-3.10 (m,
1 H), 2.98 (br s, 1 H), 2.86-2.94 (m, 3 H), 2.34 (s, 1 H), 1.25 (d,
J ) 12.88 Hz, 6 H). MS (ESI) 412.0/414.0 [(M/M + 2) + H]+.
[3-[(2,3-Dichlorophenyl)oxy]-2-(methyloxy)propyl](1,1-dimethyl-
2-[4-(methyloxy)phenyl]ethyl)amine (28). To a solution of 1-[(2,3-
dichlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(methyloxy)phenyl]eth-
yl)amino)-2-propanol (11, 0.612 g, 1.54 mmol) in DMF (15 mL)
under N2 were added sodium hydride (95%, 0.048 g, 1.90 mmol)
and iodomethane (0.12 mL, 1.92 mmol). The reaction was stirred
at room temperature for 5 days. Dilution with ethyl acetate was
followed by washes with H2O, 0.5 M HCl, and brine. The organic
layer was dried over Na2SO4, filtered, and concentrated. Column
chromatography (0-10% CH3OH:CH2Cl2) followed by evaporation
of solvent in the presence of HCl (1.0 M in Et2O) gave 0.336 g
Hz, 1 H), 3.42 (dddd, J ) 5.56, 3.79, 3.41, 2.40 Hz, 1 H), 2.95 (d,
J ) 4.04 Hz, 1 H), 2.86 (dd, J ) 4.93, 2.65 Hz, 1 H).
(2S)-2-([(2,3-Dichlorophenyl)oxy]methyl)oxirane (35). The title
compound was prepared following the procedure above substituting
(S)-nosyl epoxide for (R)-nosyl epoxide. The title compound (96%)
1
was isolated as a clear oil. H NMR (400 MHz, chloroform-d) δ
ppm 7.15 (dt, J ) 14.21, 7.17 Hz, 1 H), 7.11 (s, 1 H), 6.89 (dd, J
) 7.83, 1.77 Hz, 1 H), 4.34 (dd, J ) 11.24, 2.91 Hz, 1 H), 4.07
(dd, J ) 11.12, 5.31 Hz, 1 H), 3.42 (dddd, J ) 6.44, 3.03, 2.78,
2.65 Hz, 1 H), 2.95 (d, J ) 4.29 Hz, 1 H), 2.86 (dd, J ) 5.05, 2.53
Hz, 1 H).
(2R)-1-[(2,3-Dichlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(me-
thyloxy)phenyl]ethyl)amino)-2-propanol (32). (2R)-2-([(2,3-
Dichlorophenyl)oxy]methyl)oxirane (34, 0.44 g, 2.03 mmol) was
added to a solution of (1,1-dimethyl-2-[4-(methyloxy)phenyl]ethyl)-
amine (4, 0.359 g, 2.00 mmol) in ethanol (4.2 mL) and heated at
reflux for 2 days. The reaction was cooled and concentrated in
vacuo. Column chromatography (0-10% CH3OH:CH2Cl2) followed
by evaporation of solvent in the presence of HCl (1.0 M in Et2O)
provided 0.593 g (67%) of 32 as a white solid. 1H NMR (400 MHz,
DMSO-d6) δ ppm 8.93 (br s, 1 H), 8.65 (br s, 1 H), 7.36 (t, J )
8.21 Hz, 1 H), 7.24 (ddd, J ) 12.95, 8.40, 4.17 Hz, 2 H), 7.15 (m,
J ) 8.59 Hz, 2 H), 6.90 (m, J ) 8.59 Hz, 2 H), 5.98 (d, J ) 4.80
Hz, 1 H), 4.29 (t, J ) 6.19 Hz, 1 H), 4.12-4.25 (m, J ) 11.24,
11.24, 10.11, 5.05 Hz, 2 H), 3.74 (s, 3 H), 3.32 (d, J ) 1.77 Hz,
1 H), 3.11 (d, J ) 9.85 Hz, 1 H), 2.94 (s, 2 H), 1.22 (s, 6 H). MS
(ESI) 398.0/400.0 [(M/M + 2) + H]+.
(2S)-1-[(2,3-Dichlorophenyl)oxy]-3-((1,1-dimethyl-2-[4-(me-
thyloxy)phenyl]ethyl)amino)-2-propanol (33). The title compound
was prepared following the procedure above substituting (2S)-2-
([(2,3-dichlorophenyl)oxy]methyl)oxirane (35). The title compound
(60%) was isolated as a white solid. 1H NMR (400 MHz, DMSO-
d6) δ ppm 8.98 (br s, 1 H), 8.68 (br s, 1 H), 7.35 (d, J ) 8.08 Hz,
1 H), 7.24 (ddd, J ) 12.19, 8.15, 4.17 Hz, 2 H), 7.15 (m, J ) 8.59
Hz, 2 H), 6.90 (m, J ) 8.59 Hz, 2 H), 5.99 (d, J ) 4.80 Hz, 1 H),
4.30 (t, J ) 6.19 Hz, 1 H), 4.12-4.24 (m, J ) 10.96, 10.96, 10.17,
5.05 Hz, 2 H), 3.74 (s, 3 H), 3.30 (d, J ) 12.63 Hz, 2 H), 3.15 (br
s, 1 H), 3.11 (d, J ) 9.60 Hz, 1 H), 2.94 (s, 2 H), 1.22 (s, 6 H).
MS (ESI) 398.0/400.0 [(M/M + 2) + H]+.
2-Chloro-6-([(2R)-2-oxiranylmethyl]oxy)benzonitrile (37). A
mixture of 2-chloro-6-fluorobenzonitrile (40.17 g, 258 mmol), 18-
crown-6 (22.7 g, 86 mmol), and potassium tert-butoxide (38 g, 387
mmol) in acetonitrile (350 mL) was heated at reflux under argon
overnight, whereupon 100 mL of 5 N NaOH was added and the
mixture was allowed to stir for 1 h. The acetonitrile was removed
under vacuum, and the resulting alkaline solution was extracted
twice with Et2O. The aqueous phase was then adjusted to pH ) 4
and extracted twice with Et2O. The organic extract from the acidified
aqueous phase was dried over MgSO4, filtered, and concentrated
to yield 23.8 g (60%) of 2-chloro-6-hydroxybenzonitrile as a solid.
1H NMR (400 MHz, CCDl3-d) δ ppm 7.38 (t, J ) 8.21 Hz, 1 H),
7.04 (d, J ) 7.58 Hz, 1 H), 6.96 (d, J ) 8.59 Hz, 1 H), 3.65 (br s,
1 H).
To a solution of 2-chloro-6-hydroxybenzonitrile (0.45 g, 2.93
mmol) in acetone (30 mL, 0.1 M) was added potassium carbonate
(1.21 g, 8.79 mmol). The resulting mixture stirred at reflux for 30
min. After cooling to room temperature, (2R)-2-oxiranylmethyl
3-nitrobenzenesulfonate (0.76 g, 2.93 mmol) was added. The
reaction mixture was then heated to reflux and stirred overnight at
that temperature. After cooling to room temperature, the reaction
mixture was filtered, and the filtrate was concentrated for FCC
purification (10-50% EtOAc/Hex). 2-Chloro-6-([(2R)-2-oxiranyl-
methyl]oxy)benzonitrile was obtained as a white solid (0.48 g, 79%
yield). 1H NMR (400 MHz, CDCl3-d) δ ppm 7.45 (t, J ) 8.34 Hz,
1 H), 7.11 (d, J ) 8.08 Hz, 1 H), 6.95 (d, J ) 8.34 Hz, 1 H), 4.41
(dd, J ) 11.49, 2.91 Hz, 1 H), 4.13 (dd, J ) 11.37, 5.31 Hz, 1 H),
3.41 (dt, J ) 4.11, 2.62 Hz, 1 H), 2.95 (t, J ) 4.42 Hz, 1 H), 2.86
(dd, J ) 4.80, 2.53 Hz, 1 H). LCMS m/z ) 232 (M + Na+).
2-Chloro-6-[((2R)-3-([1,1-dimethyl-2-(2-naphthalenyl)ethyl]-
amino)-2-hydroxypropyl)oxy]benzonitrile hydrochloride (38). A
solution of 2-chloro-6-([(2R)-2-oxiranylmethyl]oxy)benzonitrile (37,
1
(49%) of 28 as a white solid. H NMR (400 MHz, DMSO-d6) δ
ppm 9.26 (br s, 1 H), 8.57 (br s, 1 H), 7.37 (d, J ) 8.34 Hz, 1 H),
7.18-7.29 (m, 1 H), 7.24 (td, J ) 10.99, 7.58 Hz, 2 H), 7.14 (m,
J ) 8.59 Hz, 2 H), 6.90 (m, J ) 8.59 Hz, 2 H), 4.42 (dd, J )
10.74, 3.66 Hz, 1 H), 4.22 (dd, J ) 10.61, 4.55 Hz, 1 H), 4.10 (dd,
J ) 8.72, 3.66 Hz, 1 H), 3.74 (s, 3 H), 3.51 (s, 3 H), 3.36 (br s, 1
H), 3.18 (d, J ) 9.60 Hz, 1 H), 2.95 (s, 2 H), 1.22 (s, 6 H). MS
(ESI) 412.0/414.0 [(M/M + 2) + H]+.
3-Bromopropyl 2,3-Dichlorophenyl Ether (30). Potassium
carbonate (1.76 g, 12.7 mmol) and 1,3-dibromopropane (0.96 mL,
9.40 mmol) were added to a solution of 2,3-dichlorophenol (29,
0.512 g, 3.14 mmol) in CH3CN (25 mL). The reaction was stirred
at 70 °C for 24 h. Upon cooling, the reaction was filtered, washed
with CH3CN, and concentrated. Column chromatography (0-15%
1
ethyl acetate:hexane) provided 0.115 g (13%) of 30 as an oil. H
NMR (400 MHz, chloroform-d) δ ppm 7.15 (q, J ) 7.16 Hz, 1
H), 7.09 (ddd, J ) 7.89, 3.85, 3.66 Hz, 1 H), 6.90 (dd, J ) 8.21,
1.39 Hz, 1 H), 4.30 (t, J ) 5.94 Hz, 2 H), 4.20 (t, J ) 5.68 Hz, 1
H), 3.69 (t, J ) 6.32 Hz, 1 H), 2.31-2.42 (m, J ) 5.81, 5.81,
5.68, 5.43 Hz, 2 H).
(3-[(2,3-Dichlorophenyl)oxy]propyl)(1,1-dimethyl-2-[4-(me-
thyloxy)phenyl]ethyl)amine (31). To a solution of 30 (0.115 g,
0.405 mmol) in CH2Cl2 (1.1 mL) was added (1,1-dimethyl-2-[4-
(methyloxy)phenyl]ethyl)amine (0.080 g, 0.447 mmol). The reaction
mixture was stirred at room temperature for 18 h then at reflux for
4 days. The reaction was cooled and concentrated in vacuo. Column
chromatography (0-10% CH3OH:CH2Cl2) followed by evaporation
of solvent in the presence of HCl (1.0 M in Et2O) afforded 0.047
g (28%) of 31 as a white solid. 1H NMR (400 MHz, DMSO-d6) δ
ppm 8.95 (br s, 2 H), 7.36 (t, J ) 8.21 Hz, 1 H), 7.21 (dd, J )
18.44, 4.29 Hz, 1 H), 7.17-7.30 (m, 1 H), 7.16 (d, J ) 8.59 Hz,
2 H), 6.89 (d, J ) 8.59 Hz, 2 H), 4.39 (q, J ) 7.07 Hz, 1 H), 4.25
(t, J ) 5.94 Hz, 2 H), 3.74 (s, 3 H), 3.17 (br s, 1 H), 2.92 (s, 1 H),
2.35 (s, 1 H), 2.21 (d, J ) 6.82 Hz, 1 H), 1.35 (t, J ) 7.07 Hz, 1
H), 1.22 (s, 6 H). MS (ESI) 382.0/384.0 [(M/M + 2) + H]+.
(2R)-2-([(2,3-Dichlorophenyl)oxy]methyl)oxirane (34). To a
solution of 2,3-dichlorophenol (29, 1.03 g, 6.29 mmol) in acetone
(20 mL) was added K2CO3 (2.61 g, 18.9 mmol) and the reaction
mixture was heated at reflux for 30 min. The reaction was cooled,
(R)-nosyl epoxide (1.63 g, 6.31 mmol) was added, and reaction
heated at reflux for 3 days. The reaction was cooled, filtered, rinsed
with acetone, and concentrated in vacuo. Column chromatography
(0-30% ethyl acetate:hexane) afforded 1.27 g (92%) of 34 as a
clear oil. 1H NMR (400 MHz, chloroform-d) δ ppm 7.15 (dq, J )
7.33, 7.16 Hz, 1 H), 7.11 (s, 1 H), 6.89 (dd, J ) 7.83, 1.77 Hz, 1
H), 4.34 (dd, J ) 11.24, 2.91 Hz, 1 H), 4.07 (dd, J ) 11.12, 5.31

3992 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 13
Marquis et al.
crinol. Metab. 1999, 10, 66–71. Nemeth, E. F.; Bennett, S. A. Tricking
the parathyroid gland with novel calcimimetic agents. Nephrol., Dial.,
Transplant. 1998, 13, 1923.
0.30 g, 1.43 mmol) and [1,1-dimethyl-2-(2-naphthalenyl)ethyl]-
amine (0.28 g, 1.43 mmol) in anhydrous ethanol (7.2 mL, 0.2 M)
was heated to reflux overnight. After cooling to room temperature,
the reaction mixture was concentrated and purified by column
chromatography (1% CH3OH/CH2Cl2) to give pure product. The
resulting amine was treated with HCl in Et2O and subsequently
dried under vacuum to generate the title compound as a white solid
(7) Locatelli, F.; Pontoriero, G.; Limbardo, M.; Tentori, F. Cinacalcet
hydrochloride: calcimimnetic for the treatment of hyperparathyroidism.
Exp. Opin. Endocr. Metab. 2006, 1, 167–179. Dong, B. J. Cinacalcet:
an oral calcimimetic agent for the management of hyperparathyroidism.
Clin. Ther. 2005, 27, 1725–1751. de Francisco, A. L. M. Cinacalcet
HCL: a novel therapeutic for the treatment of hyperparathyroidism.
Exp. Opin. Pharmacother. 2005, 6, 441–452.
(8) Nemeth, E. F.; Delmar, E. C.; Heaton, W. L.; Miller, M. A.; Lambert,
L. D.; Conklin, R. L.; Gowen, M.; Gleason, J. G.; Bhatnagar, P. K.;
Fox, J. Calcilytic compounds: Potent and selective Ca+2 receptor.
antagonists that stimulate secretion of parathyroid hormone. J. Pharm.
Exp. Ther. 2001, 299, 323–331.
1
in the form of an HCl salt (0.54 g, 85%). H NMR (400 MHz,
CDCl3-d) δ ppm 7.75-7.88 (m, 3H), 7.65 (s, 1H), 7.45 (t, J )
4.17 Hz, 2H), 7.40-7.52 (m, 1H), 7.35 (dd, J ) 8.46, 1.64 Hz,
1H), 7.09 (d, J ) 8.08 Hz, 1H), 6.91 (d, J ) 8.59 Hz, 1H), 4.15
(dd, J ) 4.80, 2.78 Hz, 2H), 4.05 (dd, J ) 6.44, 4.67 Hz, 1H),
3.09 (dd, J ) 12.00, 4.42 Hz, 1H), 2.96 (d, J ) 6.82 Hz, 1H), 2.93
(d, J ) 2.27 Hz, 2H), 2.44 (br s, 2H), 1.19 (s, 3H), 1.18 (s, 3H).
LCMS m/z ) 409 (M + H+). Elemental anal. calcd: 64.72% C,
5.88% H, 6.29% N; found: 64.52% C, 5.70% H, 6.28% N.
(9) Gowen, M.; Stroup, G. B.; Dodds, R. A.; James, I. E.; Votta, B. J.;
Smith, B. R.; Bhatnagar, P. K.; Lago, A. M.; Callahan, J. F.; Del Mar,
E. G.; Miller, M. A.; Nemuth, E. F.; Fox, J. Antagonizing the
parathyroid calcium receptor stimulates parathyroid secretion and bone
formation in osteopenic rats. J. Clin. InVest. 2000, 105, 1595–1604.
(10) Arey, B. J.; Seethala, R.; Ma, Z.; Fura, A.; Morin, J.; Swartz, J.; Vyas,
V.; Yang, W., Jr.; Feyen, J. H. M. A Novel Calcium-Sensing Receptor
Antagonist Transiently Stimulates Parathyroid Hormone Secretion in
Vivo. Endocrinology 2005, 5, 1131–1136.
Acknowledgment. We thank Drs. John Gleason and Brian
Metcalf for their support of this work.
Supporting Information Available: X-ray crystallographic data
for antagonist 38 as well as HPLC purities with two separate
conditions for antagonists 7-11, 13-17, 21-24, 26-28, and
31-33. This material is available free of charge via the Internet at
http://pubs.acs.org.
(11) Dauban, P.; Ferry, S.; Faure, H.; Ruat, M.; Dodd, R. H. N1-
Arylsulfonyl-N2-(1-aryl)ethyl-3-phenylpropane-1,2-diamines as Novel
Calcimimetics Acting on the Calcium Sensing Receptor. Bioorg. Med.
Chem. Lett. 2000, 10, 2001–2004.
(12) Kessler, A.; Faure, H.; Ruat, M.; Dauban, P.; Dodd, R. H. N2-Benzyl-
N1-(1-(1-naphthyl)ethyl)-3-phenylpropane-1,2-diamines and confor-
mationally constrained indole analogs: development of calindol as a
new calcimimetic acting at the calcium sensing receptor. Bioorg. Med.
Chem. Lett. 2004, 14, 3345–3349.
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