Discovery of 4,4-disubstituted quinazolin-2-ones as T-type calcium channel antagonists

Article abstract of DOI:10.1021/ml100004r

A novel series of quinazolinone T-type calcium channel antagonists have been prepared and evaluated using in vitro and in vivo assays. Optimization of the screening hit 3 by modifications of the 3- and 4-positions of the quinazolinone ring afforded potent

Full text of DOI:10.1021/ml100004r

pubs.acs.org/acsmedchemlett
Discovery of 4,4-Disubstituted Quinazolin-2-ones as
T-Type Calcium Channel Antagonists
James C. Barrow,*,† Kenneth E. Rittle,† Thomas S. Reger,† Zhi-Qiang Yang,†
Phung Bondiskey,† Georgia B. McGaughey,† Mark G. Bock,† George D. Hartman,†
Cuyue Tang,‡ Jeanine Ballard,‡ Yuhsin Kuo,‡ Thomayant Prueksaritanont,‡ Cindy E. Nuss,§
Scott M. Doran,§ Steven V. Fox,§ Susan L. Garson,§ Richard L. Kraus,§ Yuxing Li,§
Michael J. Marino, Valerie Kuzmick Graufelds, Victor N. Uebele,§ and John J. Renger§
Departments of †Medicinal Chemistry, ‡Drug Metabolism and Pharmacokinetics, §Depression and Circadian Disorders, and
Parkinson's Disease, Merck Research Laboratories, WP14-1, P.O. Box 4, Sumneytown Pike, West Point, Pennsylvania 19486
ABSTRACT A novel series of quinazolinone T-type calcium channel antagonists
have been prepared and evaluated using in vitro and in vivo assays. Optimization of
the screening hit 3 by modifications of the 3- and 4-positions of the quinazolinone
ring afforded potent and selective antagonists that displayed in vivo central
nervous system efficacy in epilepsy and tremor models, as well as significant
effects on rat active wake as measured by electrocorticogram.
KEYWORDS Quinazolin-2-ones, calcium channel antagonists, electrocorticogram,
T-type calcium channel, epilepsy, tremor
oltage-gated calcium channels represent potential
drug targets because of their critical role in many
physiological processes.1 On the basis of cloning
1 and 2 (Figure 1) that show in vivo efficacy in epilepsy and
tremor models while having minimal effects on the cardio-
vascular system.12,13 As part of the high-throughput FLIPR
screen that discovered the piperidine series from which 1
and 2 were derived, another class of compounds exempli-
fied by quinazolinone 3 (Figure 1) was identified. Quinazo-
linones such as 3 were initially prepared at Merck as HIV non-
nucleoside reverse transcriptase inhibitors (NNRTI), and
much is known about this heterocycle, making it an attrac-
tive starting point for further investigation.14 Furthermore,
the high-throughput screening (HTS) results gave clear struc-
ture-activity relationship (SAR) trends that were used to
prioritize initial analogue synthesis.
Compounds were prepared by the methods established
for the NNRTIs,15 as shown in Scheme 1. Amino benzophe-
nones 4 were treated with carbonyl diimidazole followed by
the desired primary amine to give an equilibrium mixture of
5 and 6. When R = Et or cyclopropyl, simple heating of this
mixture in toluene and removal of water with a Dean-Stark
trap afforded the dehydrated product 7 as a crystalline solid
that was isolated directly from the reaction mixture. Com-
pound 7 could be treated with a Grignard reagent to give the
desired compounds 8, which were resolved into their re-
spective enantiomers by chiral chromatography. Determina-
tion of the absolute stereochemistry was done by X-ray
anomalous dispersion of brominated analogues (see the
Supporting Information)16 for 10 and 12 with the others
V
of the main pore-forming R-subunit, they can be divided
into three main families: Cav1.x (L-type), Cav2.x (N-, P/Q-,
R-type), and Cav3.x (T-type).2 A number of clinically useful
drugs modulate L-type channels,1 and the development of
ziconotide has stimulated more interest in the N-type cal-
cium channel.3 The T-type calcium channel is also attracting
a lot of interest for the treatment of peripheral and central
nervous system (CNS) disorders. Of the three T-type calcium
channels, the Cav3.1 and Cav3.3 subtypes are primarily
expressed in the brain, while Cav3.2 has a broader central
and peripheral expression.4 Initial investigations of peri-
pheral T-type calcium channel antagonists focused on their
potential role in blood pressure regulation, resulting in the
identification of mibefradil, which was briefly marketed as
an antihypertensive.5 While mibefradil has some in vitro
selectivity for T-type channels over L-type, the lack of blood
pressure lowering in L-type calcium channel conditional
knockout mice suggests that results with mibefradil should
be interpreted with caution.6 In the CNS, T-type calcium
channels have been proposed to be involved in a number of
conditions, especially sleep,7,8 epilepsy,9 and pain.10 T-type
channels are highly expressed in the thalamus and cortex
and play important roles in thalamocortical signaling.11
Therefore, we sought to identify compounds with better
selectivity for T-type channels than mibefradil and with the
potential for brain penetration to evaluate how modulation
of these channels could be used to treat CNS disorders.
Recent reports from these laboratories have disclosed
piperidine-based selective T-type calcium channel antagonists
Received Date: January 5, 2010
Accepted Date: January 22, 2010
Published on Web Date: February 01, 2010
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ing the two FLIPR assays, there was more than a 10-fold
difference in potency depending on the resting membrane
potential of the test cell line, making it more state-dependent
than other inhibitors that we have studied to date such as 1
and 2 (Figure 1). However, it is very common for ion channel
blockers to exhibit state-dependent inhibition. Examples of
state-dependent drugs include nifedipine (L-type Ca2þ
channels)23 and phenytoin (Naþ channels).24 Unknown
was whether state-dependent blockers would have the same
in vivo effects as the piperidines 1 and 2, making 9 a useful
tool to probe the differences.
An additional property of 9 important for inhibition of
central T-type channels in vivo is that it is not a substrate for
the P-glycoprotein transporter (P-gp) as demonstrated in a
BA/AB ratio of 1.6 in a P-gp-expressing cell line.25 Two hours
after oral dosing in rats, it was determined that 9 had a brain:
plasma ratio of 1.3:1, demonstrating its value as an in vivo
tool to compare this series to the previously disclosed
piperidines. We began with a rat genetic model of absence
epilepsy using Wistar albino Glaxo rats bred in Rijswijk, The
Netherlands (WAG/Rij). These rats display cortical EEG pat-
terns and physical behaviors characteristic of an epileptic
condition, including frequent seizures.26 Because T-type
calcium channels are involved in the regulation of thalamo-
cortical rhythms that underlie these seizures, measurement
of EEG in these animals serves as a relevant pharmaco-
dynamic readout of brain penetration and T-type channel
activity. Similar to piperidines 1 and 2, compound 9 dis-
played robust inhibition of seizure time, with a 61% reduc-
tion over the first 4 h after oral dosing at 3 mg/kg. The simi-
lar effect of compound 9 in this model, despite showing a
10-fold shift in potency in the FLIPR assays, suggests that a
state-dependent inhibitor has similar effects to a state-
independent inhibitor in this animal model.
Further profiling of 9 in metabolic assays showed it to be a
time-dependent inhibitor (TDI) of CYP3A4,27 with only 15%
of total CYP3A4 activity remaining after a 30 min preincuba-
tion with 9. Because cyclopropyl amines are notorious for
this effect,28 we explored other 3-position analogues. It was
found that a small alkyl group was required for potency, and
a trifluoroethyl proved to be both potent and metabolically
robust. The addition of a fluorine to the 4-phenyl of the
quinazolinone produced 10, which was a weaker CYP3A4
TDI relative to 9. A full pharmacokinetic profile of 10 showed
it to have a half-life of 3-4 h across species and good
bioavailability in rat and rhesus (Table 2).
Figure 1. T-type calcium channel antagonists.
Scheme 1a
a Reagents: (a) CDI, CH2Cl2,45°C. (b) R-NH2 THF, 50 °C. (c) Toluene, 110 °C.
(d) R0MgBr, THF, -5 °C. (e) Et3N, SOCl2, THF, -5 °C.
assigned by analogy. When R = trifluoroethyl, it was not
possible to isolate the dehydrated product 7. Therefore, the
procedure of Magnus et al.17 was employed whereby treat-
ment of the mixture of 5 and 6 with thionyl chloride and
triethylamine in THF generates intermediate 7 in situ, followed
by addition of a large excess of the Grignard reagent to afford
the 4,4-disubstituted quinazolinones 8 where R = trifluor-
oethyl.
The potency on the T-type calcium channel was deter-
mined by two FLIPR assays designed to measure potency on
the inactivated state of the channel (depolarized assay) and
the resting state of the channel (hyperpolarized assay) as
previously described.20 Initial SAR, from both mining the
plethora of quinazolinone analogues already prepared for
the NNRTI program and targeted synthesis showed that the
lead was resistant to drastic changes. Replacement of the
methyl group at the 3-position of the lead with an ethyl group
yielded a slight improvement in potency, and resolution of
enantiomers provided compounds 8a and 8b, which showed
that the majority of the activity resides in one enan-
tiomer (Table 1). It was known from the NNRTI literature14
that rapid N-dealkyation of the quinazolinone position 3 alkyl
group limited oral bioavailability of these compounds; there-
fore, compound 9 (TTA-Q2)21 was prepared with a cyclopro-
pyl group at the 3-position to limit this pathway. This
modification afforded a compound with significant bioavail-
ability (44%)22 while improving potency on the T-type
channel, especially in the depolarized state assay. Compar-
Further profiling of 10 revealed moderate activation (63%
as compared to positive control rifampicin) of the pregnane
X receptor (PXR) in an in vitro SEAP assay.29 Activation of
PXR could lead to induction of CYP3A4 and thus poses a
potential risk of drug-drug interactions; therefore, minimi-
zation of this activity is desirable.30 Molecular modeling
suggested29 that introduction of polar groups on the 4-aryl
ring may help reduce the propensity to bind to the PXR
receptor. While this approach generally led to significant
reductions in potency, a nitrile at the 4-position was best
tolerated. Further exploration of the 4-alkyl substituent
demonstrated a significant boost in potency with the intro-
duction of a cyclopropane at the 4-position such as com-
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Table 1. In Vitro and in Vivo Data for T-Type Calcium Channel Antagonists
a Data are presented as means ( standard deviations as described in ref 20. b Data are the average of n=2 measurements. The assay is as described
in ref 18. c Data are the average of n=2 measurements. The assay is as described in ref 19. d The inhibition of seizure duration was calculated 4 h after
dosing relative to vehicle dosing on the previous day as an average of n=2 rats. e Basolateral to apical/apical to basolateral transport ratio in human
MDR1 transfected cells (see ref 25). f Time-dependent inhibition of CYP 3A4 activity, expressed as percent testosterone 6β-hydroxylase activity
remaining following 30 min of preincubation (see ref 27). g Initial weak signal followed up in CYP3A4 enzyme assay: kinact value of 0.044 min-1 and Ki
value of 2.9 μM. h % response of PXR activation relative to Rifampicin at 10 μM (see ref 29). i Rat oral bioavailability in Sprague-Dawley rats, 10 mpk oral
dose (n=3), 2 mpk iv dose (n=2).
Table 2. Pharmacokinetic Parameters of 10
Table 3. Pharmacokinetic Parameters of 12
CLp
Vdss
plasma protein
CLp
Vdss
plasma protein
species (mL/min/kg)
T
1/2 (h) (L/kg) F (%) binding (% bound)a
species (mL/min/kg) T
1/2 (h) (L/kg) F (%) binding (% bound)a
rat
22
10
4.3
3.8
3.3
6
100
6b
94
98
97
rat
12
11
5.9
4.9
9.5
4
49
78
46
98.7
99.0
98.8
dog
2.2
8.1
dog
3.6
4.2
rhesus
8.1
32
rhesus
5.2
a Determined by ultracentrifugation with 14C-labeled 10 at 4 μM.
a Determined by equilibrium dialysis with 14C-labeled 12 at 5 μM.
b Significant emesis immediately postdose.
pound 11 (Table 1); however, this change was accompanied
by an increase in PXR activation to 99% of rifampicin.
Combining the cyclopropane with the 4-cyano modification
afforded compound 12 (TTA-Q6), which has good potency
and reduced PXR activation as compared to 11. Further
evaluation with human hepatocytes showed a slight improve-
ment with compound 12 over compound 10 (20 vs 45% of
CYP3A4 mRNA increase relative to rifampicin at 1 μM).
Compound 12 also displayed a good pharmacokinetic pro-
file across species as shown in Table 3 and was not a PGP
substrate (Table 1), with a brain to plasma ratio in rats of 1.1
measured 2 h after oral dosing at 10 mpk.
Figure 2. Inhibition of the T-type calcium channel Cav3.3 subtype
by 12 as determined by standard voltage clamp. Data points reflect
means ( SEs of three determinations. IC50 values of 221 nM and
1 μM were determined at -80 and -100 mV, respectively. Error
bars for -100 mV are hidden behind symbols.
Confirmation of the FLIPR potency was done by whole cell
patch clamp recording at two holding potentials, -100 and
-80 mV. Compound 12 showed potencies of 1 μM and221 nM,
respectively (Figure 2).
Compounds in this series were also evaluated in a binding
assay and shown to be positive allosteric modulators of the
binding ligand as previously described.20 Compound 12 was
the most potent modulator identified in the series with an
inflection point of 0.8 nM.31 To examine ion channel selec-
tivity, compound 12 was assayed against important cardiac
sodium and potassium channels using planar patch clamp
technology. Compound 12 is not a potent inhibitor of the
Nav1.5, IKr, and IKs channels with IC50 >10 μM on these chan-
nels. Despite its remaining similarity to the HIV NNRTI 3,
compound 12 was inactive (>10 μM) in a HIV reverse
transcription assay.14
Both 10 and 12 displayed good overall profiles and were
examined in several in vivo assays responsive to T-type
calcium channel antagonists. Both compounds showed robust
inhibition of seizures in the WAG/Rij epilepsy model after
oral dosing at 3 mg/kg (Table 1). Essential tremor is also
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Figure 4. Effect of 12 on N = 7 male SD rat active sleep for 23 h
after dosing 10 mg/kg po. Data are average minutes of active wake
in each 30 min bins (( SEM) starting at dose time (grey triangle).
Gray bars above denote significant differences (p < 0.05, mixed
ANOVA analysis).
Figure 3. Dose response of 10 in the harmaline-induced rat model
of essential tremor after po dosing at 3 and 10 mpk in 90% PEG400
(n=8-10 per dose). *p<0.001 global F test.
channel modulation of important CNS processes including,
epilepsy, tremor, and sleep.
associated with thalamocortical dysfunction,32 and a rat
harmaline-induced tremor model has been established to
evaluate T-type calcium channel antagonists.33 Piperidines 1
and 2 were shown to be efficacious in this model,12,13 and
compound 10 was examined in a similar manner. The rats
were dosed with compound 10 and 60 min later were given
10 mg/kg harmaline, which induces a tremor in the 6-12 Hz
range that is dose dependently suppressed by 10 as shown in
Figure 3.
SUPPORTING INFORMATION AVAILABLE Experimental
procedures and analytical data for compounds 8-12. This material
is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author: *To whom correspondence should
be addressed. Tel: 215-652-4780. Fax: 215-652-6345. E-mail:
james_barrow@merck.com.
Another important process that has a significant thalamo-
cortical component is regulation of arousal. To evaluate the
effects of T-type antagonists on sleep and wake, telemetric
recordings of electrocorticogram (ECoG) and electromyo-
gram (EMG) signals were measured in rats. In a 7 day cross-
over design, vehicle or compound 12 was dosed orally every
day, 30 min before the inactive phase (lights on for rats). The
ECoG and EMG signals were collected and scored for the
amount of time awake or each phase of sleep (light sleep,
delta sleep, REM).
ACKNOWLEDGMENT We thank Nicole Pudvah for PGP mea-
surements; Ken Anderson, Leslie Geer, and Debra McLoughlin for
PK analysis; Charles Ross and Joan Murphy for high-resolution mass
spectral analysis; Carl Homnick and ZhiQiang Wang for chiral
separations; Sinoeun Touch for performing the NNRTI assay; Elena
S. Trepakova for ion channel profiling; and Richard Ball, Arlene
McKeown, and Nancy Tsou for X-ray crystallography.
REFERENCES
Remarkably, a 10 mg/kg dose of 12 to rats right before
their sleep period produced a further suppression of active
wake for 0.5-2 h after dosing, a consistent effect that began
prior to lights on (Figure 4). Plasma concentrations, as
estimated from dosing nonimplanted satellite animals, was
between 3 and 4 μM. The effects on active wake in rats by 12
were similar to those seen when 9, 10, or 11 was dosed at
10 mpk (data not shown). Furthermore, the sleep/wake
effect of quinazolinones 9-12 is similar to the structurally
distinct piperidines 1 and 2, as well as the recently reported
T-type antagonist TTA-A2,34 suggesting the common involve-
ment of T-type calcium channels. A full account of the effects
of T-type calcium channel antagonists on sleep architecture
will be disclosed shortly.35
In conclusion, the quinazolinone HTS hit 3 was optimized
for potency on the T-type channel, brain penetration, and
bioavailability while minimizing ancillary activities such as
CYP inhibition and induction. The optimized quinazolinones
10 and 12 have a robust in vivo profile of seizure and tremor
suppression as well as active wake suppression in rats. Locali-
zation of T-type calcium channels in thalamocortical circuits
coupled with the similar in vivo effects of structurally distinct
classes of inhibitors suggests a critical role for T-type calcium
(1)
Zamponi, G. W. Voltage-Gated Calcium Channels; Kluwer
Academic/Plenum Publishers: New York, 2005.
(2)
Ertel, E. A.; Campbell, K. P.; Harpold, M. M.; Hofmann, F.;
Mori, Y.; Perez-Reyes, E.; Schwartz, A.; Snutch, T. P.; Tanabe,
T.; Birnbaumer, L.; Tsien, R. W.; Catterall, W. A. Nomenclature
of voltage-gated calcium channels. Neuron 2000, 25, 533–
535.
Yamamoto, T.; Takahara, A. Recent Updates of N-Type Cal-
cium Channel Blockers with Therapeutic Potential for Neuro-
pathic Pain and Stroke. Curr. Top. Med. Chem. 2009, 9, 377–
395.
Talley, E. M.; Cribbs, L. L.; Lee, J. H.; Daud, A.; Perez-Reyes, E.;
Bayliss, D. A. Differential Distribution of Three Members of a
Gene Family Encoding Low Voltage-Activated (T-Type) Cal-
cium Channels. J. Neurosci. 1999, 19, 1895–1911.
Clozel, J. P.; Ertel, E. A.; Ertel, S. I. Discovery and main
pharmacological properties of mibefradil (Ro 40-5967), the
first selective T-type calcium channel blocker. J. Hypertens.
1997, 15, S17–S25.
Moosmang, S.; Haider, N.; Bruderl, B.; Welling, A.; Hofmann,
F. Antihypertensive effects of the putative T-type calcium
channel antagonist Mibefradil are mediated by the L-type
calcium channel Ca(v)1.2. Circ. Res. 2006, 98, 105–110 .
Llinas, R. R.; Steriade, M. Bursting of thalamic neurons and
states of vigilance. J. Neurophysiol. 2006, 95, 3297–3308.
(3)
(4)
(5)
(6)
(7)
r
2010 American Chemical Society
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pubs.acs.org/acsmedchemlett
(8)
(9)
Crunelli, V.; Cope, D. W.; Hughes, S. W. Thalamic T-type Ca2þ
channels and NREM sleep. Cell Calcium 2006, 40 (2), 175–190.
Varela, D.; Khosravani, H.; Heron, S. E.; Bladen, C.; Williams,
T. C.; Newman, M.; Berkovic, S. F.; Scheffer, I. E.; Mulley, J. C.;
Zamponi, G. W. Functional characterization of genetically
identified variants in the T-type calcium channel gene CAC-
NA1H associated with idiopathic epilepsy. Biophys. J. 2007,
601A–602A.
McManus, O. B.; Swensen, A. M. A high-throughput assay for
evaluating state dependence and subtype selectivity of Cav2
calcium channel inhibitors. Assay Drug Dev. Technol. 2008, 6,
195–212.
(20) Uebele, V. N.; Nuss, C. E.; Fox, S. V.; Garson, S. L.; Cristescu,
R.; Doran, S. M.; Kraus, R. L.; Santarelli, V. P.; Li, Y.; Barrow,
J. C.; Yang, Z. Q.; Schlegel, K. A.; Rittle, K. E.; Reger, T. S.;
Bednar, R. A.; Lemaire, W.; Mullen, F. A.; Ballard, J. E.; Tang,
C.; Dai, G.; McManus, O. B.; Koblan, K. S.; Renger, J. J. Posi-
tive allosteric interaction of structurally diverse T-type cal-
cium channel antagonists. Cell Biochem. Biophys. 2009, 55,
81–93.
(21) The TTA-Qx nomenclature is provided for consistency across
publications, such as ref 20.
(22) Bioavailability was enhanced by the use of nonaqueous
vehicles such as 1:1 imwitor:tween or PEG400.
(23) Hockerman, G. H.; Peterson, B. Z.; Johnson, B. D.; Catterall,
W. A. Molecular determinants of drug binding and action on
L-type calcium channels. Annu. Rev. Pharmacol. Toxicol. 1997,
37, 361–396.
(24) Kuo, C. C.; Bean, B. P. Slow Binding of Phenytoin to Inacti-
vated Sodium-Channels in Rat Hippocampal-Neurons. Mol.
Pharmacol. 1994, 46, 716–725.
(25) Hochman, J. H.; Pudvah, N.; Qiu, J.; Yamazaki, M.; Tang, C.;
Lin, J. H.; Prueksaritanont, T. Interactions of human P-glyco-
protein with simvastatin, simvastatin acid, and atorvastatin.
Pharm. Res. 2004, 21, 1686–1691.
(26) Coenen, A. M. L.; Drinkenburg, W. H. I. M.; Inoue, M.;
Vanluijtelaar, E. L. J. M. Genetic Models of Absence Epilepsy,
with Emphasis on the Wag Rij Strain of Rats. Epilepsy Res.
1992, 12, 75–86.
(27) Tang, C.; Subramanian, R.; Kuo, Y.; Krymgold, S.; Lu, P.;
Kuduk, S. D.; Ng, C.; Feng, D. M.; Elmore, C.; Soli, E.; Ho, J.;
Bock, M. G.; Baillie, T. A.; Prueksaritanont, T. Bioactivation of
2,3-Diaminopyridine-Containing Bradykinin B-1 Receptor
Antagonists: Irreversible Binding to Liver Microsomal Pro-
teins and Formation of Glutathione Conjugates. Chem. Res.
Toxicol. 2005, 18, 934–945.
(28) Cerny, M. A.; Hanzlik, R. P. Cyclopropylamine inactivation of
cytochromes P450: Role of metabolic intermediate com-
plexes. Arch. Biochem. Biophys. 2005, 436, 265–275.
(29) Gao, Y. D.; Olson, S. H.; Balkovec, J. M.; Zhu, Y.; Royo, I.;
Yabut, J.; Evers, R.; Tan, E. Y.; Tang, W.; Hartley, D. P.; Mosley,
R. T. Attenuating pregnane X receptor (PXR) activation: A
molecular modelling approach. Xenobiotica 2007, 37, 124–
138.
(10) Todorovic, S. M.; Jevtovic-Todorovic, V. The Role of T-Type
Calcium Channels in Peripheral and Central Pain Processing.
CNS Neurol. Disord.: Drug Targets 2006, 5, 639–653.
(11) Cueni, L.; Canepari, M.; Adelman, J. P.; Luthi, A. Ca2þ
signaling by T-type Ca2þ channels in neurons. Pflugers Arch.
Eur. J. Physiol. 2009, 457, 1161–1172.
(12) Shipe, W. D.; Barrow, J. C.; Yang, Z. Q.; Lindsley, C. W.; Yang,
F. V.; Schlegel, K. A. S.; Shu, Y.; Rittle, K. E.; Bock, M. G.;
Hartman, G. D.; Tang, C.; Ballard, J. E.; Kuo, Y.; Adarayan,
E. D.; Prueksaritanont, T.; Zrada, M. M.; Uebele, V. N.; Nuss,
C. E.; Connolly, T. M.; Doran, S. M.; Fox, S. V.; Kraus, R. L.;
Marino, M. J.; Graufelds, V. K.; Vargas, H. M.; Bunting, P. B.;
Hasbun-Manning, M.; Evans, R. M.; Koblan, K. S.; Renger, J. J.
Design, Synthesis, And Evaluation of a Novel 4-Amino-
methyl-4-fluoropiperidine as a T-Type Ca2þ Channel Antago-
nist. J. Med. Chem. 2008, 51, 3692–3695.
(13) Yang, Z. Q.; Barrow, J. C.; Shipe, W. D.; Schlegel, K. A. S.; Shu,
Y. S.; Yang, F. V.; Lindsley, C. W.; Rittle, K. E.; Bock, M. G.;
Hartman, G. D.; Uebele, V. N.; Nuss, C. E.; Fox, S. V.; Kraus,
R. L.; Doran, S. M.; Connolly, T. M.; Tang, C. Y.; Ballard, J. E.;
Kuo, Y. S.; Adarayan, E. D.; Prueksaritanont, T.; Zrada, M. M.;
Marino, M. J.; Graufelds, V. K.; DiLella, A. G.; Reynolds,
I. J.; Vargas, H. M.; Bunting, P. B.; Woltmann, R. F.;
Magee, M. M.; Koblan, K. S.; Renger, J. J. Discovery of 1,4-
Substituted Piperidines as Potent and Selective Inhibitors of
T-Type Calcium Channels. J. Med. Chem. 2008, 51, 6471–
6477.
(14) Tucker, T. J.; Lyle, T. A.; Wiscount, C. M.; Britcher, S. F.; Young,
S. D.; Sanders, W. M.; Lumma, W. C.; Goldman, M. E.; Obrien,
J. A.; Ball, R. G.; Homnick, C. F.; Schleif, W. A.; Emini, E. A.;
Huff, J. R.; Anderson, P. S. Synthesis of a Series of 4-(Aryl-
ethynyl)-6-chloro-4-cyclopropyl-3,4-dihydroquinazolin-2(1H)-
ones as Novel Nonnucleoside Hiv-1 Reverse-Transcriptase
Inhibitors. J. Med. Chem. 1994, 37, 2437–2444.
(15) Corbett, J. W.; Ko, S. S.; Rodgers, J. D.; Gearhart, L. A.;
Magnus, N. A.; Bacheler, L. T.; Diamond, S.; Jeffrey, S.; Klabe,
R. M.; Cordova, B. C.; Garber, S.; Logue, K.; Trainor, G. L.;
Anderson, P. S.; Erickson-Viitanen, S. K. Inhibition of Clini-
cally Relevant Mutant Variants of HIV-1 by Quinazolinone
Non-nucleoside Reverse Transcriptase Inhibitors. J. Med.
Chem. 2000, 43, 2019–2030.
(16) CCDC 760574 and CCDC 760575 contain the supplementary
crystallographic data for this paper. These data can be obtain-
ed free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
(17) Magnus, N. A.; Confalone, P. N.; Storace, L.; Patel, M.; Wood,
C. C.; Davis, W. P.; Parsons, R. L. General Scope of 1,4-
Diastereoselective Additions to a 2(3H)-Quinazolinone: Prac-
tical Preparation of HIV Therapeutics. J. Org. Chem. 2003, 68,
754–761.
(18) Xia, M. H.; Imredy, J. P.; Koblan, K. S.; Bennett, P.; Connolly,
T. M. State-dependent inhibition of L-type calcium channels:
Cell-based assay in high-throughput format. Anal. Biochem.
2004, 327, 74–81.
(30) Bertilsson, G.; Heidrich, J.; Svensson, K.; Asman, M.; Jendeberg,
L.; Sydow-Backman, M.; Ohlsson, R.; Postlind, H.; Blomquist, P.;
Berkenstam, A. Identification of a human nuclear receptor
defines a new signaling pathway for CYP3A induction. Proc.
Natl. Acad. Sci. U.S.A. 1998, 95, 12208–12213.
(31) The assay is described in ref 20.
(32) Troster, A. I.; Woods, S. P.; Fields, J. A.; Lyons, K. E.; Pahwa, R.;
Higginson, C. I.; Koller, W. C. Neuropsychological deficits in
essential tremor: an expression of cerebello-thalamo-cortical
pathophysiology? Eur. J. Neurol. 2002, 9, 143–151.
(33) Miwa, H. Rodent models of tremor. Cerebellum 2007, 6,
66–72.
(34) Uebele, V. N.; Gotter, A. L.; Nuss, C. E.; Kraus, R. L.; Doran,
S. M.; Garson, S. L.; Reiss, D. R.; Li, Y. X.; Barrow, J. C.; Reger,
T. S.; Yang, Z. Q.; Ballard, J. E.; Tang, C. Y.; Metzger, J. M.;
Wang, S. P.; Koblan, K. S.; Renger, J. J. Antagonism of T-type
calcium channels inhibits high-fat diet-induced weight gain in
mice. J. Clin. Invest. 2009, 119, 1659–1667.
(19) Dai, G.; Haedo, R. J.; Warren, V. A.; Ratliff, K. S.; Bugianesi,
R. M.; Rush, A.; Williams, M. E.; Herrington, J.; Smith, M. M.;
(35) Doran, S. Manuscript in preparation.
r
2010 American Chemical Society
79
DOI: 10.1021/ml100004r ACS Med. Chem. Lett. 2010, 1, 75–79
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