Synthesis and Biological Evaluation of Cyclopentaquinoline Derivatives as Nonsteroidal Glucocorticoid Receptor Antagonists

Article abstract of DOI:10.1021/jm501758q

The steroidal glucocorticoid antagonist mifepristone has been reported to improve the symptoms of depression. We report the discovery of 6-(3,5-dimethylisoxazol-4-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclopenta[h]quinolin-3-one 3d (QCA-1093) as a novel nonsteroidal glucocorticoid receptor antagonist. The compound displayed potent in vitro activity, high selectivity over other steroid hormone receptors, and significant antidepressant-like activity in vivo.

Full text of DOI:10.1021/jm501758q

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Article
Synthesis and Biological Evaluation of Cyclopentaquinoline
Derivatives as Nonsteroidal Glucocorticoid Receptor Antagonists
Masahiro Eda, Tomoko Kuroda, Satoshi Kaneko, Yoshiyuki Aoki, Masami Yamashita, Chieko
Okumura, Yoshitaka Ikeda, Tomoko Ohbora, Masaki Sakaue, Natsumi Koyama, and Keiichi Aritomo
J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/jm501758q • Publication Date (Web): 15 May 2015
Downloaded from http://pubs.acs.org on May 19, 2015
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Synthesis and Biological Evaluation of
Cyclopentaquinoline Derivatives as Nonsteroidal
Glucocorticoid Receptor Antagonists
*†
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§
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Masahiro Eda, Tomoko Kuroda, Satoshi Kaneko, Yoshiyuki Aoki, Masami
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Yamashita, Chieko Okumura, Yoshitaka Ikeda, Tomoko Ohbora, Masaki Sakaue,
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Natsumi Koyama and Keiichi Aritomo
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Medicinal Chemistry Research Laboratories, Pharmacology Research Laboratories,
#
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DMPK Research Laboratories, Product Quality Assurance Department, Research
▼
Strategy & Planning Department, and Tanabe R&D Service Synthetic Chemistry
Department, Mitsubishi Tanabe Pharma Corporation, 2ꢀ2ꢀ50 Kawagishi, Toda, Saitama
3
35ꢀ8505, Japan
ABSTRACT: The steroidal glucocorticoid antagonist mifepristone has been reported to
improve the symptoms of depression. We report the discovery of
6ꢀ(3,5ꢀdimethylisoxazolꢀ4ꢀyl)ꢀ2,2,4,4ꢀtetramethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]
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quinolinꢀ3ꢀone 3d (QCAꢀ1093) as a novel nonsteroidal glucocorticoid receptor antagonist.
The compound displayed potent in vitro activity, high selectivity over other steroid
hormone receptors, and significant antidepressantꢀlike activity in vivo.
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KEYWORDS: glucocorticoid receptor antagonist, QCAꢀ1093, antidepressant,
tetrahydroquinoline, mifepristone.
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Introduction
Physiological and psychological stress promotes the activation of the hypothalamic–
pituitary–adrenal axis causing the secretion of glucocorticoid hormones from the adrenal
cortex. Glucocorticoid hormones bind to glucocorticoid receptors (GRs) in the brain and
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induce various anxiety/depressionꢀrelated symptoms such as increased sadness,
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suppression of food ingestion, and neuronal loss in the hippocampus. The steroidal GR
antagonist mifepristone (1, Figure 1) has been reported to improve the symptoms of
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depression. However, an abortifacient effect due to the potent progesterone receptor (PR)
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antagonist activity, rapid clearance from the body, and crossꢀreactivity with other steroid
hormone receptors hampered its use as an antidepressant agent. Multiple groups attempted
to address these limitations through the synthesis of selective nonsteroidal GR antagonists,
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namely chromene or arylindazole derivatives. We focused on developing a novel, potent,
and selective nonsteroidal GR antagonist for the treatment of depression.
In a highꢀthroughput screening of compounds using luciferase reporter assays, we
identified tetrahydroquinoline derivative 3a as a human GR (hGR) antagonist (IC = 37
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nM). The binding affinities (Ki) of 3a to hGR and human PR (hPR) were 16 nM and 22 nM,
respectively, which were similar to those of mifepristone (hGR, Ki = 6 nM; hPR, Ki = 15
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nM). Tetrahydroquinoline 2, a nonsteroidal PR antagonist, with a high binding affinity to
PR (Ki = 3.9 nM), exhibits a panꢀsteroid receptor inhibitory activity for hPR, hGR, the
human androgen receptor (hAR), and the human mineralocorticoid receptor (hMR) in
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competitive binding assays. We modified the structures of suitable tetrahyrdroquinolines,
such as compound 2 and 3a, as lead compounds to obtain a GR selective antagonist with
selectivity over other steroid hormone receptors.
In this paper, we demonstrated that the optimization of 3a led to the identification of
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ꢀ(3,5ꢀdimethylisoxazolꢀ4ꢀyl)ꢀ2,2,4,4ꢀtetramethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]
quinolinꢀ3ꢀone 3d (QCAꢀ1093) as a novel nonsteroidal GR antagonist. The compound
displayed potent in vitro activity, high selectivity over other steroid hormone receptors, and
significant antidepressantꢀlike activity in vivo.
Chemistry
Schemes 1 and 2 present an outline of the synthesis of tetrahydroquinolineꢀ3ꢀones 3a-f
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and 12a-k following the published procedures with a slight modification.
Dihydroquinoline 4 was prepared by the Skraup reaction of acetone with commercially
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available substituted aniline in the presence of iodine
or catalytic scandium
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trifluoromethanesulfonate. The hydroboration of olefin and conversion of the hydroxyl
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group followed by bromination of 4 afforded alcohol 6. After protection of the alcohol with
a tertꢀbutyldimethylsilyl (TBDMS) group and protection of the amine with a Boc group, the
TBDMS group was removed by tetrabutylammonium fluoride to yield alcohol 7. Alcohol 7
was oxidized by pyridinium chlorochromate and methylated by methyl iodide to give
ketone 9. Ketone 9 was esterified with bis(pinacolato)diboron in the presence of a catalytic
amount of [1,1′ꢀbis(diphenylphosphino)ferrocene] palladium to synthesize boronic acid
ester 11. A series of compounds (3a-f and 12a-k) were obtained by the Suzuki coupling
reaction between the boronic acid ester and appropriate halides (aryl halide or compound 9)
followed by acidic deprotection.
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Biological results and discussion
The synthesized compounds were evaluated for their hGR antagonistic activity (IC ) in a
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wholeꢀcell luciferase assay and binding affinities (Ki) to hGR, hPR, and hMR. The initial
modification of the aromatic and heteroaromatic rings at the isoxazole moiety of 3a did not
produce a potent and selective hGR antagonist (see supporting information, Table 6). The
structures and in vitro data of the compounds with substituents on the tetrahydroquinoline
ring are summarized in Table 1. The introduction of a chloro (3b) or methoxy (3c) group at
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the 7 position (R ) on the tetrahydroquinoline ring of compound 3a led to a significant
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decrease in the binding potency to hGR. Cyclopentaquinoline 3d, in which R and R were
joined by a three methylene linker, displayed hGR binding potency and antagonistic
activity comparable to those of 3a with a remarkable improvement in its selectivity for hPR
and hMR. Dexamethasone increased the luciferase signal by approximately 200% at 10 nM.
In the same luciferase assay without dexamethasone, 3d itself was not an agonist because
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d increased the luciferase activity by only 4% from baseline, even at a concentration of 1
M. Increasing the length of the methylene linker as cyclohexaquinoline 3e significantly
decreased the binding potency to hGR. The insertion of oxygen to the linker as [1,
]dioxoloquinoline 3f led to a 3ꢀfold decrease in the hGR binding potency with a
ꢁ
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significant selectivity for hPR and hMR.
We examined the introduction of a variety of aromatic and heteroaromatic rings at the
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isoxazole moiety (R ) while maintaining the cyclopentaquinoline template. Exchanging R
with a benzene or mono substituted benzene ring system resulted in a reduction of the
binding potency (orthoꢀ, metaꢀ, or paraꢀF, Cl, OMe, OH, CN, see supporting information,
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Table 7). The results of substitution with the fiveꢀmembered heterocycles in R are
presented in Table 2. The 1,4ꢀdimethylimidazolꢀ5ꢀyl derivative 12b displayed a 4ꢀfold
decrease in hGR binding potency and the 1,4ꢀdimethylpyrazolꢀ5ꢀyl derivative 12a exhibited
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similar hGR binding potency and selectivity as those of 3d. It was noted that the hGR
binding potencies of 1,3ꢀdimethylpyrazolꢀ5ꢀyl 12c and 1,4ꢀdimethylimidazoylꢀ2ꢀyl 12d
were significantly low. These results indicate that the high affinity hGR binding required
the electronegativity of oxygen and/or nitrogen and two lipophilic methyl substituents at
suitable positions on the fiveꢀmembered heterocycle structure.
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In an attempt to expand structure–activity relationship (SAR), we modified the isoxazole
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moiety (R ) to a variety of 5,6ꢀ or 6,6ꢀ condensed ring systems. Because the
imidazopyridine derivative 12e displayed similar GR binding potency and selectivity as
those of 3d, it is likely that a desirable combination of the electronic and lipophilic effects
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in the R unit was represented with this compound. Replacement of the imidazopyridine
structure in 12e with a pyrazolopyridine group in 12f led to a 3ꢀfold decrease in the GR
binding activity. A systematic investigation of the effect of the addition of nitrogen atoms
on 12e revealed that a reduction of lipophilicity resulted in 4ꢀfold decline in the hGR
binding activity in 12g and 12h and a considerable loss of potency in 12i. Substitution with
a 6,6ꢀ condensed ring system reduced the hGR binding activity (1,8ꢀnaphthyridine 12k)
3ꢀfold. Based on the observed low binding potency for hPR and hMR, the scaffold of
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cyclopentaquinoline in R was essential for the hGR selectivity.
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GR is a part of a large multiprotein complex in the cytoplasm that includes a heat shock
protein. Upon ligand binding, a conformational change of the GRꢀligand complex leads to
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the dissociation of these chaperones and the translocation of GR to the nucleus. Once in
the nucleus, GR interacts with the DNA sequences and transcription factors to initiate or
repress gene transcription. Ligands that compete only with agonists for GR binding are
called “passive” antagonists, whereas those that compete also for the binding of the agonist
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receptor complex and DNA sequences are called “active” antagonists. As Schoch reported
that the “active” and “passive” antagonist conformations from the Xꢀray crystal structure of
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the hGR ligandꢀbinding domain (LBD) bind to mifepristone (PDB code: 3H52), we
analyzed the conformation of the two types of Xꢀray cocrystal structures with the docking
simulation of 3d and GR using the Glide program, as shown in Figure 2. In both models,
the negative charge in the izoxazole moiety of 3d accepted a hydrogen bond from Arg611
in the same manner as the C ketone in mifepristone. We noted that the cyclopentyl moiety
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of 3d interacted with the lipophilic cavity of GR formed by Met601, Ala605, Leu608,
Met646, and Leu732. However, the corresponding amino acid Ala605 of PR was Val760.
The lipophilic cavity in PR was presumably unable to adjust to the cyclopentyl moiety
because of a steric clash. Therefore, 3d may be unfavorable as a PR ligand, although it is
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unclear as to which simulation models better explains why 3d has high affinity and
selectivity to GR.
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The crossꢀreactivity of 3d with other steroid receptors was assessed by binding assays
using the human estrogen receptors (hERα and hERβ) and hAR (Table 3). Compound 3d
displayed high selectivity for hGR over these steroidal receptors.
The pharmacokinetic analysis of compound 3d (10 mg/kg, p.o. and 1 mg/kg, i.v. in male
Sprague–Dawley rats) revealed a moderate halfꢀlife and excellent oral bioavailability of the
compound in the rats (Table 4). The unbound brain to plasma ratio (Kp, uu, brain), which is
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a parameter of the brain penetration potential, was determined to estimate the potential of
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d as an antidepressant drug candidate. The ratio of the unbound brain concentration (Cb,u:
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5.7 nmol/kg) to the unbound plasma concentration (Cp,u: 14.1 nmol/L) was 1.8 at 1 h
after the oral dosing (30 mg/kg) of compound 3d in the rats. From Kp, uu, brain, and Cb,u
we estimated that a sufficient brain penetration of 3d would be achieved after 30 mg/kg
oral dosing for in vivo evaluation.
We tested the antidepressantꢀlike activity of 3d in the rat forced swimming test, which is
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used as a model of depression. In this test, rats are forced to swim in a cylinder with water
and they struggle to escape, after which they become resigned to float on the surface of
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water with minimum movements. It was reported that tricyclic antidepressants and
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mifepristone decrease the immobility time. In our result, the immobility time was
significantly decreased by mifepristone (30 mg/kg, 3 times, p.o.) and compound 3d (30 and
100 mg/kg 3 times, p.o.) (Table 5). The effect of 3d (30 mg/kg, 3 times) was comparable
with that of mifepristone (30 mg/kg, 3 times). The significant effects of both mifepristone
and 3d on the immobility time in the forced swimming test suggest that the antagonism of
GR contributed to the antidepressantꢀlike effects of these compounds.
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Currently, pharmacological, pharmacokinetic, and toxicological studies on this series of
GR antagonist are underway. We are preparing another detailed report on the
pharmacological evaluation of a representative GR antagonist. Therefore, a further
discussion on this compound series will be present in this later report.
Conclusion
A series of novel cyclopentaquinolines were developed and examined for their activity in
the luciferase reporter assay and binding affinity to hGR. The new compounds
demonstrated improved selectivity for hGR over other steroid hormone receptors. Among
them, compound 3d (QCAꢀ1093) exhibited excellent penetration into the brain and in vivo
activity in the forced swimming test in rats. These results indicate that QCAꢀ1093 has
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potential as a new antidepressant and warrants further pharmacological evaluation as a GR
antagonist.
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Experimental Section
Chemistry
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General. Reagents, starting materials, and solvents were purchased from commercial
suppliers and were used as received. Reactions were run under a nitrogen atmosphere at an
ambient temperature unless otherwise specified. Chromatography refers to the flash
chromatography conducted on Kieselgel 60 230–400 mesh (E. Merck, Darmstadt) using the
indicated solvents. Medium pressure liquid chromatography was performed on Purifꢀα
(Shoko Scientific) with Purifi pack normal phase Silica gel (30–60 ꢁm) columns and UV
detection at 254 nm. The melting points were determined with a Yanaco melting point
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apparatus and were uncorrected. H and C NMR spectra were measured on Bruker
DPXꢀ300 or AVANCE III 400. The NMR signals were expressed in ppm downfield from
tetramethylsilane as the internal standard (δ = 0). Splitting patterns are designed as follows:
s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; and br, broad. Mass spectra (MS)
were recorded on a Waters ACQUITY SQD instrument operating with electrospray
ionization and Thermo Scientific MSQ Plus instrument operating with atmospheric
pressure chemical ionization. Elemental analyses for carbon, hydrogen, and nitrogen were
conducted with Yanaco MTꢀ6 and were within ±0.4% of the theoretical values for the
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formulae given. The purity of the final compounds was determined by HPLC with UV
detection at 220 nm and 254 nm. The conditions of the isocratic elution method (isocratic
HPLC) were as follows: column, SUMIPAX ODS Dꢀ210SLP (Sumika Chemical Analysis
Service, Ltd.); isocratic elution, mixture of CH CN and H O with 0.05% TFA for 12 min;
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3
2
and flow rate, 1 mL/min. The conditions of the linear gradient method (gradient HPLC)
were as follows: column, Chromolish Speed ROD (Merck Millipore); gradient elution, 10–
1
00% CH CN in water with 0.05% TFA for 4.5 min and maintaining 100% CH CN with
3 3
0
.05% TFA for 2.5 min; and flow rate, 2 mL/min. All final compounds were >95% pure.
The highꢀresolution mass spectrometry (HRMS) experiments were performed with Thermo
Fisher Scientific LTQ Orbitrap Velos Pro using electrospray positive ionization.
Synthesis of
6
-(3,5-Dimethylisoxazol-4-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclopenta
[h]quinolin-3-one (3d). Step 1:
2,2,4ꢀTrimethylꢀ2,7,8,9ꢀtetrahydroꢀ1Hꢀcyclopenta[h]quinoline (4d).
Scandium (III) trifluoromethanesulfonate (4.99 g, 0.010 mol) was added to a solution of
4ꢀaminoindane (22.5 g, 0.169 mol) in acetone (500 mL), and the mixture was stirred at
room temperature for 7 days. The reaction mixture was filtered through celite. The solvent
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was evaporated under reduced pressure, and the residue was purified by flash
chromatography using hexane/AcOEt (20:1) as an eluent. After evaporation, the product
0
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was obtained as a slightly orange solid (21.8 g, 60%). MS m/z [M+H] 214. H NMR (400
MHz, CDCl3) 6.92 (d, J = 7.6 Hz, 1H), 6.55 (d, J = 7.6 Hz, 1H), 5.24 (s, 1H), 2.86 (t, J =
7.4 Hz, 2H), 2.63 (t, J = 7.4 Hz, 2H), 2.06 ꢀ 2.13 (m, 2H), 1.98 (s, 3H), 1.29 (s, 6H). C
NMR (101 MHz, CDCl3) 144.9, 139.2, 128.9, 126.7, 126.0, 122.2, 119.0, 112.6, 51.8,
3.3, 31.5, 28.8, 25.0, 19.0.
Step 2: 2,2,4ꢀTrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]quinolinꢀ3ꢀol (5d). One
δ
1
3
δ
3
molar borane/THF solution (200 mL) under ice cooling for over 1 h was added dropwise to
a solution of 4d (23.7 g, 0.111 mol) in THF (200 mL), and the mixture was stirred at 15 °C
for 6 h. THF/water (1:1, 100 mL) was added dropwise to the reaction solution over 15 min.
Aqueous sodium hydroxide solution (3 N, 67 mL) was added over 15 min and 30%
aqueous hydrogen peroxide (22.5 mL) was added dropwise over 5 min. The mixture was
stirred at room temperature for 1.5 h. The reaction solution was poured into water, and the
mixture was extracted with AcOEt. The organic layer was washed with saturated aqueous
sodium hydrogen carbonate and saturated brine and was dried over sodium sulfate. The
solvent was evaporated under reduced pressure, and the residue was purified by flash
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chromatography and was eluted with a gradient of hexane/AcOEt (20/1) to hexane/AcOEt
(3/1). After the evaporation, the product was obtained as a brown oil (23.9 g, 90%). MS m/z
10
11
12
13
14
15
16
17
18
19
20
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[M+H] 232. H NMR (400 MHz, DMSOꢀd )
δ
7.18 (d, J = 7.7Hz, 1H), 7.08 (br, 1H), 3.30
6
(d, J = 9.4 Hz, 1H), 3.04 (m, 1H), 2.83 (t, J = 6.9 Hz, 2H), 2.72 (m, 1H), 2.63 (m, 1H), 2.03
1
3
(m, 2H), 1.46 (s, 3H), 1.33 (d, J = 6.6 Hz, 3H), 1.11 (s, 3H). C NMR (101 MHz,
DMSOꢀd6) 143.7, 134.9, 129.8, 126.9, 121.7, 74.3, 57.3, 35.0, 32.2, 30.1, 24.7, 24.4,
8.1, 17.3.
Step 3: 6ꢀBromoꢀ2,2,4ꢀtrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]quinolinꢀ3ꢀol
6d). A solution of bromine (16.0 g, 0.100 mol) in CHCl (50 mL) under ice cooling for
δ
1
(
3
over 1 h was added to a solution of 5d (23.9 g, 0.100 mol) in CHCl (240 mL) dropwise,
3
and the mixture was stirred at room temperature for 3 h. The reaction solution was adjusted
to pH 12 with 10% aqueous sodium hydroxide solution (240 mL) and was poured into
water. The mixture was then extracted with CHCl . The organic layer was washed with
3
water and saturated brine and was dried over sodium sulfate. The solvent was evaporated
under reduced pressure, and the residue was purified by flash chromatography and was
eluted with a gradient of hexane/AcOEt (10/1) to hexane/AcOEt (3/1). After the
+
evaporation, the product was obtained as a white solid (21.5 g, 71%). MS m/z [M+H] 310.
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H NMR (400 MHz, CDCl3)
δ
7.13 (s, 1H) 3.36 (s, 1H), 3.31 (dd, J = 9.4, 6.1 Hz, 1H),
2
.90 (t, J = 7.5 Hz, 2H), 2.72 (t, J = 7.5 Hz, 2H), 2.68 ꢀ 2.74 (m, 1H), 2.07 ꢀ 2.15 (m, 2H),
0
1
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9
0
1
3
1.71 (d, J = 6.1 Hz, 1H), 1.41 (d, J = 6.5 Hz, 3H), 1.31 (s, 3H), 1.08 (s, 3H). C NMR (101
MHz, CDCl3) 142.6, 138.0, 128.9, 128.7, 124.5, 106.9, 78.4, 52.9, 35.9, 34.5, 30.5, 27.8,
δ
23.8, 21.2, 18.2.
Step 4:
6
ꢀBromoꢀ3ꢀ(tertꢀbutyldimethylsilyloxy)ꢀ2,2,4ꢀtrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopent
a[h]quinoline. Imidazole (9.80 g, 144 mmol) and tertꢀbutyldimethylchlorosilane (10.9 g,
2.0 mmol) were added to a solution of 6d (11.2 g, 36.0 mmol) in DMF (47 mL), and the
7
mixture was stirred at 100 °C for 8.5 h. The reaction solution was diluted with ice water
and was adjusted to pH 10 with saturated aqueous sodium hydrogen carbonate. The mixture
was then extracted with ethyl acetate. The organic layer was washed with water and
saturated brine and was dried over sodium sulfate. The solvent was evaporated under
reduced pressure, and the residue was purified by flash chromatography and was eluted
with a gradient of hexane to hexane/AcOEt (20/1). After the evaporation, the product was
+
1
obtained as a slightly orange solid (14.3 g, 96%). MS m/z [M+H] 424. H NMR (300 MHz,
CDCl3) 7.12 (s, 1H), 3.37 (t, J = 6.9Hz, 1H), 2.90 (t, J = 5.8 Hz, 2H), 2.73 (brt, 2H), 2.11
δ
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(
m, 2H), 1.33 (d, J = 5.2 Hz, 3H), 1.25 (s, 3H), 1.06 (s, 3H), 0.96 (s, 9H), 0.14 (s, 3H), 0.12
1
3
10
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(s, 3H). C NMR (101 MHz, CDCl ) δ 142.4, 138.1, 128.6, 128.6, 125.5, 106.8, 79.6, 53.6,
3
36.5, 34.5, 30.5, 29.4, 26.2, 23.8, 21.4, 18.8, 18.5, ꢀ3.2, ꢀ3.2.
Step 5: tertꢀButyl
6ꢀBromoꢀ3ꢀ(tertꢀbutyldimethylsilyloxy)ꢀ2,2,4ꢀtrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopent
a[h]quinolineꢀ1ꢀcarboxylate. One point six molar nꢀbutyllithiumꢀhexane solution (19.1 mL,
3
0.5 mmol) was added dropwise over 20 min to a solution of the compound of the previous
step (12.3 g, 29.0 mmol) in THF (70 mL) cooled to −45 °C, and the mixture was stirred at
45 °C for 30 min and then at 0 °C for 2 h. Diꢀtertꢀbutyl dicarbonate (9.80 g, 58.0 mmol) in
−
THF (32 mL) was added to this solution at 0 °C, and the mixture was stirred at room
temperature for 6 h. The reaction solution was poured into ice water (150 mL), and the
mixture was extracted with ethyl acetate (150 mL × 2). The organic layer was washed with
saturated brine and was dried over sodium sulfate. The solvent was evaporated under
reduced pressure, and the residue was purified by flash chromatography and was eluted
with a gradient of hexane to hexane/AcOEt (9/1). After the evaporation, the product was
1
obtained as a yellow oil (16.2 g, quant.). H NMR (300 MHz, CDCl )
δ 7.05 (s, 1H) 3.22 (d,
3
J = 5.8 Hz, 1H), 2.91 (m, 2H), 2.74 (m, 2H), 1.93 ꢀ 2.20 (m, 2H), 1.50 (s, 3H), 1.46 (s, 9H),
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6
1
.30 (s, 3H), 1.27 (d, J = 5.3Hz, 3H), 0.92 (s, 9H), 0.13 (s, 3H), 0.11 (s, 3H).
Step 6: tertꢀButyl
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6ꢀBromoꢀ3ꢀhydroxyꢀ2,2,4ꢀtrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]quinolineꢀ1ꢀca
rboxylate (7d). One molar tetrabutylammonium fluorideꢀTHF solution (170 mL, 170
mmol) was added to a solution of the compound of the previous step (47.0 g, 89.6 mmol) in
THF (180 mL), and the mixture was stirred at 60 °C for 3 h. The reaction solution was
diluted with ice water, and the mixture was extracted with ethyl acetate. The organic layer
was washed with saturated brine and was dried over sodium sulfate. The solvent was
evaporated under reduced pressure, and the residue was purified by flash chromatography
and was eluted with a gradient of hexane/AcOEt (20/1) to hexane/AcOEt (5/1). After the
evaporation, the product was obtained as a colorless powder (31.0 g, 83%). MS m/z
+
1
[
M+H] 410. H NMR (300 MHz, CDCl )
δ
7.10 (s, 1H), 3.16 (t, J = 4.7Hz, 1H), 2.90 (m,
3
2
H), 2.74 (m, 2H), 1.93 ꢀ 2.20 (m, 2H), 1.91 (d, J = 4.7 Hz, 1H), 1.50 (s, 3H), 1.47 (s, 9H),
1
3
1.38 (s, 3H), 1.37 (d, J = 4.7 Hz, 3H). C NMR (101 MHz, CDCl ) δ 154.1, 143.3, 141.6,
3
136.1, 134.6, 126.0, 115.6, 81.0, 80.7, 60.5, 36.9, 34.7, 33.0, 28.3, 27.2, 24.6, 20.2, 16.0.
Step 7: tertꢀButyl
6
ꢀBromoꢀ2,2,4ꢀtrimethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]quinolinꢀ3ꢀoneꢀ1ꢀcarboxy
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late (8d). Pyridinium chlorochromate (23.5 g, 109 mmol) and 4A molecular sieves (29.8 g)
awere added to a solution of 7d (29.8 g, 72.5 mmol) in CH Cl (90 mL), and the mixture
10
11
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60
2
2
was stirred at room temperature for 7 h. The reaction mixture was filtered through celite,
and the solvent was evaporated under reduced pressure. The residue was purified by flash
chromatography and was eluted with a gradient of hexane to hexane/AcOEt (10/1). After
the evaporation, the product was obtained as a colorless powder (25.5 g, 86%). MS m/z
+
1
[
M+H] 408. H NMR (400 MHz, CDCl )
δ
7.08 (s, 1H), 3.88 (br, 1H), 3.00 ꢀ 3.06 (m, 1H),
3
2
1
1
.93ꢀ2.96 (m, 2H), 2.63 ꢀ 2.68 (m, 1H), 2.16 (br, 1H), 1.93 ꢀ 2.03 (m, 1H), 1.71 (br, 3H),
13
.52 (s, 9H), 1.44 (d, J = 6.7 Hz, 3H), 1.31 (br, 3H). C NMR (101 MHz, CDCl )
δ
152.5,
3
44.7, 141.2, 134.7, 130.6, 125.3, 117.2, 81.4, 65.5, 34.7, 33.0, 28.4, 25.6, 24.7.
Step 8: tertꢀButyl
6
ꢀBromoꢀ2,2,4,4ꢀtetramethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]quinolinꢀ3ꢀoneꢀ1ꢀcar
boxylate (9d). One point six molar lithium bis(trimethylsilyl)amideꢀTHF solution (15.7 mL,
16.8 mmol) was added drop wise over 10 min to a solution of 8d (1.71 g, 4.19 mmol) in
THF (29 mL)cooled to −50 °C, and the mixture was heated to −20 °C. Iodomethane (1.05
mL, 16.8 mmol) was the added, and the mixture was stirred at room temperature for 3 h.
The reaction mixture was poured into ice water, and the mixture was extracted with ethyl
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acetate. The organic layer was washed with saturated brine and was dried over sodium
sulfate. The solvent was evaporated under reduced pressure, and the residue was purified
by flash chromatography and was eluted with a gradient of hexane to hexane/AcOEt (20/1).
After the evaporation, the product was obtained as a white powder (1.60 g, 90%). MS m/z
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
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8
9
0
1
2
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7
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0
+
1
[
M+H] 422. H NMR (400 MHz, CDCl ) δ 7.18 (s, 1H), 2.94 (t, J = 7.5 Hz, 2H), 2.84 (br,
3
1
3
2
2
2
H), 2.07 (br, 2H), 1.50 (s, 9H), 1.47 (s, 6H), 1.41 (br, 6H). C NMR (101 MHz, CDCl ) δ
3
12.7, 152.4, 144.8, 142.2, 135.2, 134.4, 125.9, 117.0, 81.3, 65.3, 47.7, 34.7, 32.8, 28.4,
4.6.
Step 9:
6
ꢀ(3,5ꢀDimethylisoxazolꢀ4ꢀyl)ꢀ2,2,4,4ꢀtetramethylꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclopenta[h]
quinolinꢀ3ꢀone (3d). (Method A). Two molar aqueous potassium carbonate solution (60 mL,
1
6
20 mmol), 3,5ꢀdimethylꢀ4ꢀ(4,4,5,5ꢀtetramethylꢀ1,3,2ꢀdioxaborolanꢀ2ꢀyl)isoxazole (13.4 g,
0.0 mmol), and tetrakis(triphenylphosphine)palladium (0) (3.70 g, 3.20 mmol) were added
to a solution of 9d (16.9 g, 40.0 mmol) in isopropanol (320 mL), and the mixture was
stirred at 80 °C for 16 h. The reaction mixture was poured into water, and the mixture was
extracted with ethyl acetate. The organic layer was washed with saturated brine and was
dried over sodium sulfate. The solvent was evaporated under reduced pressure, and the
2
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residue was purified by flash chromatography and was eluted with a gradient of
hexane/AcOEt (20/1) to hexane/AcOEt (3/1). After the evaporation, the tꢀBocꢀprotected
intermediate 10d was obtained as a white powder (9.15 g). Trifluoroacetic acid (51 mL)
10
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20
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was added to the powder (11.3 g) dissolved in CHCl (26 mL), and the mixture was stirred
3
at room temperature for 4 h. The reaction mixture was poured into ice water, neutralized
with 3N aqueous NaOH solution (220 mL), and extracted with CHCl . The organic layer
3
was washed with saturated brine and was dried over sodium sulfate. The solvent was
evaporated under reduced pressure, and the residue was purified by flash chromatography
and was eluted with a gradient of hexane to hexane/AcOEt (4/1). After the evaporation, the
product (7.77 g, 46%, two step yield) was obtained as a white powder, mp 192.5ꢀ193.1 °C.
+
1
HRMSꢀESI m/z [M+H] calcd for C H N O , 339.20670; found 339.20519. H NMR
2
1
26
2
2
(300 MHz, CDCl3) δ 6.79 (s, 1H) 2.80 (t, J = 7.5 Hz, 2H), 2.68 (t, J = 7.5 Hz, 2H), 2.27 (s,
1
3
3
H), 2.16 (s, 3H), 2.11 ꢀ 2.18 (m, 2H), 1.44 (s, 6H), 1.36 (s, 6H). C NMR (101 MHz,
DMSOꢀd6) δ 214.8, 164.9, 159.5, 143.4, 138.4, 129.2, 127.4, 125.4, 117.5, 116.3, 59.9,
46.7, 32.4, 29.3, 27.8, 24.7, 24.7, 11.7, 10.7. Found C, 74.67; H, 7.75; N, 8.26. C H N O
2
21
26
2
requires C, 74.53; H, 7.74; N, 8.28%. 99.8% purity at UV220 and 254 nm based on
isocratic HPLC (t = 4.05 min, CH CN/water 60/40).
R
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Synthesis of
,2,4,4-Tetramethyl-6-([1,2,4]triazolo[4,3-a]pyridin-5-yl)-2,3,4,7,8,9-hexahydro-1H-cyc
2
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0
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2
3
4
5
6
7
8
9
0
lopenta[h]quinolin-3-one (12h). Step 1: tertꢀButyl
2,2,4,4ꢀTetramethylꢀ6ꢀ(4,4,5,5ꢀtetramethylꢀ[1,3,2]dioxaborolanꢀ2ꢀyl)ꢀ2,3,4,7,8,9ꢀhexahydro
ꢀ1Hꢀcyclopenta[h]quinolinꢀ3ꢀoneꢀ1ꢀcarboxylate (11). Bis(pinacolato)diboron (3.61 g, 14.2
mmol), potassium acetate (2.09 g, 21.3 mmol), and
[
1,1’ꢀbis(diphenylphosphino)ferrocene]palladium (II) dichloride (260 mg, 0.31 mmol) were
added to a solution of the compound of 9d (3.00 g, 7.10 mmol) in isopropanol (42 mL) ,
and the mixture was stirred at 80 °C for 6 h. The reaction solution was diluted with ethyl
acetate, and the precipitate was filtered off. The solvent was evaporated under reduced
pressure, and the residue was purified by flash chromatography and was eluted with
hexane/AcOEt (20/1). After the evaporation, the product (3.30 g, 100%) was obtained as a
+
1
brown powder. MS m/z [M+H] 470. H NMR (400 MHz, CDCl ) δ 7.45 (s, 1H), 3.12 (br,
3
1
3
2H), 2.73 (br, 2H), 2.01 (br, 2H), 1.55 (s, 6H), 1.49 (s, 9H), 1.49 (br, 6H), 1.29 (s, 12H). C
NMR (101 MHz, CDCl3) 213.4, 152.5, 152.3, 139.8, 137.7, 131.7, 129.8, 83.4, 80.9, 65.4,
δ
47.7, 34.2, 31.2, 28.4, 26.6, 24.9.
Step 2:
2
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9
2
,2,4,4ꢀTetramethylꢀ6ꢀ([1,2,4]triazolo[4,3ꢀa]pyridinꢀ5ꢀyl)ꢀ2,3,4,7,8,9ꢀhexahydroꢀ1Hꢀcyclop
enta[h]quinolinꢀ3ꢀone (12h). (Method B). Two molar aqueous potassium carbonate
solution (6.4 mL, 12.8 mmol), 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine (0.654g, 4.26 mmol),
and tetrakis(triphenylphosphine)palladium (0) (0.148 g, 0.13 mmol) were added to a
solution of 11 (2.00 g, 4.26 mmol) in DMF (30 mL) , and the mixture was stirred at 110 °C
for 4 h. The reaction mixture was poured into water, and the mixture was extracted with
ethyl acetate. The organic layer was washed with saturated brine and was dried over sodium
sulfate. The solvent was evaporated under reduced pressure. Trifluoroacetic acid (20 mL)
was added to the residue dissolved in CH Cl (20 mL), and the mixture was stirred at room
10
11
12
13
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15
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24
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32
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36
37
38
39
40
41
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44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2
2
temperature for 1 h. The reaction mixture was poured into ice water, neutralized with 1N
aqueous NaOH solution, and extracted with CHCl . The organic layer was washed with
3
saturated brine and was dried over sodium sulfate. The solvent was evaporated under
reduced pressure, and the residue was purified by flash chromatography and was eluted
with a gradient of CHCl to CHCl /MeOH (9/1). After evaporation, the product (0.624 g,
3
3
+
41%, two step yield) was obtained as a slightly yellowish powder. HRMSꢀESI m/z [M+H]
1
calcd for C H N O, 361.20229; found 361.20100. H NMR (400 MHz, DMSOꢀd )
δ
8.92
2
2
24
4
6
(s, 1H), 7.74 (d, J = 9.2 Hz, 1H), 7.44 (dd, J = 9.2, 2.4Hz, 1H), 7.25 (s, 1H), 6.89 (d, J = 6.6
2
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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
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5
5
5
5
5
5
5
5
5
6
Hz, 1H), 5.61 (s, 1H), 2.87 (t, J = 7.3 Hz, 2H), 2.70 (t, J = 7.3 Hz, 2H), 2.01 ꢀ 2.08 (m, 2H),
1
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1.38 (s, 6H), 1.31 (s, 6H). C NMR (101 MHz, DMSOꢀd ) δ 214.4, 149.3, 142.0, 140.6,
6
136.5, 135.1, 129.8, 128.2, 126.6, 124.0, 118.9, 113.5, 113.0, 59.1, 45.9, 31.9, 29.6, 26.7,
24.5. 98.3% purity at UV220 nm and 99.4% purity at UV254 nm based on isocratic HPLC
(t = 2.55 min, CH CN/water 40/60).
R
3
Synthesis of
6
-(2,4-Dimethyl-2H-pyrazol-3-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclop
enta[h]quinolin-3-one (12a). With a method using 5ꢀbromoꢀ1,4ꢀdimethylꢀ1Hꢀpyrazole
instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12a was
+
obtained as a white powder (19 mg, 32%). HRMSꢀESI m/z [M+H] calcd for C H N O,
2
1
27
3
1
3
3
3
38.22269; found 338.22125. H NMR (400 MHz, DMSOꢀd )
δ
7.30 (s, 1H), 6.84 (s, 1H),
6
.53 (s, 3H), 2.83 (t, J=7.41 Hz, 2H), 2.57 (t, J=7.61 Hz, 2H), 1.97 ꢀ 2.10 (m, 2H), 1.83 (s,
1
3
H), 1.35 (s, 3H), 1.34 (s, 3H), 1.25 ꢀ 1.30 (m, 6H). C NMR (101 MHz, DMSOꢀd )
δ
6
214.7, 142.9, 140.4, 139.4, 137.7, 129.0, 126.3, 125.0, 116.1, 113.2, 59.1, 45.8, 36.6, 31.9,
29.5, 26.6, 24.7, 24.6, 24.4, 9.0. 97.4% purity at UV 220 nm and 97.0% purity at UV 254
nm based on isocratic HPLC (t = 2.12 min, CH CN/water 55/45).
R
3
Synthesis of
2
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Journal of Medicinal Chemistry
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9
6
-(3,5-Dimethyl-3H-imidazol-4-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclo
penta[h]quinolin-3-one (12b). With a method using 5ꢀbromoꢀ1,4ꢀdimethylꢀ1Hꢀimidazole
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12a was
+
obtained as a white powder (21 mg, 94%). HRMSꢀESI m/z [M+H] calcd for C H N O,
2
1
27
3
1
3
3
2
1
2
38.22269; found 338.22157. H NMR (400 MHz, CDCl )
δ
7.50 (s, 1H). 6.68 (s, 1H),
3
.59 (br, 1H), 3.39 (s, 3H), 2.80 (t, J = 7.5 Hz, 2H), 2.57 ꢀ 2.77 (m, 2H), 2.11 ꢀ 2.18 (m, 2H),
1
3
.11 (s, 3H), 1.44 (s, 6H), 1.38 (s, 3H), 1.36 (s, 3H). C NMR (101 MHz, CDCl ) δ 214.8,
3
44.5, 138.8, 136.1, 134.9, 129.0, 128.3, 127.2, 126.2, 117.3, 59.9, 46.7, 32.5, 31.9, 29.3,
7.8, 24.8, 24.7, 13.4. 97.9% purity at UV220 nm and 97.5% purity at UV254 nm based on
gradient HPLC (t = 2.15 min).
R
Synthesis of
6
-(1,3-Dimethyl-1H-pyrazol-5-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclop
enta[h]quinolin-3-one (12c). With a method using 5ꢀbromoꢀ1,3ꢀdimethylꢀ1Hꢀpyrazole
instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12c was
+
obtained as a white powder (17 mg, 31%). HRMSꢀESI m/z [M+H] calcd for C H N O,
2
1
27
3
1
338.22269; found 338.22150. H NMR (400 MHz, DMSOꢀd )
δ
6.92 (s, 1H), 5.99 (s, 1H),
6
5
.33 (brs., 1H), 3.59 (s, 3H), 2.81 (t, J = 7.29 Hz, 2H), 2.73 (t, J = 7.43 Hz, 2H), 2.15 (s,
2
5
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Page 26 of 53
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1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
1
3
3
2
H), 2.02 (m, 2H), 1.35 (s, 6H), 1.22 ꢀ 1.29 (m, 6H). C NMR (101 MHz, DMSOꢀd ) δ
6
14.7, 145.5, 143.0, 142.2, 139.2, 129.1, 126.2, 124.3, 116.9, 105.0, 59.1, 45.8, 36.4, 32.3,
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
29.6, 26.6, 24.6, 24.3, 13.2. 98.4% purity at UV220 nm and 97.7% purity at UV254 nm
based on isocratic HPLC (t = 2.12 min, CH CN/water 55/45).
R
3
Synthesis of
-(1,4-Dimethyl-1H-imidazol-2-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclo
6
penta[h]quinolin-3-one (12d). With a method using 2ꢀbromoꢀ1,4ꢀdimethylꢀ1Hꢀimidazole
instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12d was
+
obtained as a white powder (19 mg, 32%). HRMSꢀESI m/z [M+H] calcd for C H N O,
2
1
27
3
1
3
7
2
1
38.22269; found 338.22153. H NMR (400 MHz, DMSOꢀd )
δ
7.47 (d, J = 0.83 Hz, 1H),
6
.26 (s, 1H), 5.86 (s, 1H), 3.66 (s, 3H), 2.84 (m, 4H), 2.29 (d, J = 0.83 Hz, 3H), 2.08 (m,
1
3
H), 1.37 (s, 6H), 1.30 (s, 6H). C NMR (101 MHz, DMSOꢀd ) δ 213.9, 143.8, 143.7,
6
42.1, 129.7, 128.2, 126.5, 125.7, 120.2, 108.1, 59.1, 45.8, 34.7, 31.6, 29.6, 26.6, 24.7, 24.3,
9.6. 98.8% at UV220 nm and 97.8% purity at UV254 nm based on isocratic HPLC (t =
R
2.68 min, CH CN/water 35/65).
3
Synthesis of
6
-(Imidazo[1,2-a]pyridin-5-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclopent
2
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Journal of Medicinal Chemistry
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a[h]quinolin-3-one (12e). With a method using 5ꢀbromoꢀimidazo[1,2ꢀa]pyridine instead of
5
ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12e was obtained as a
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
+
white powder (41 mg, 77%). HRMSꢀESI m/z [M+H] calcd for C H N O, 360.20704;
2
3
25
3
1
found 360.20555. H NMR (400 MHz, DMSOꢀd )
δ
7.54 (d, J = 8.8 Hz, 1H), 7.43 (s, 1H),
6
7.29 (dd, J = 8.8, 6.6 Hz, 1H), 7.16 (s, 1H), 6.81 (d, J = 6.6 Hz, 1H), 5.52 (s, 1H), 2.86 (t, J
1
3
=
7.1 Hz, 2H), 2.63 (t, J = 7.1 Hz, 2H), 1.99 ꢀ 2.05 (m, 2H), 1.36 (s, 6H), 1.31 (s, 6H). C
NMR (101 MHz, DMSOꢀd ) δ 214.5, 145.2, 141.9, 140.2, 138.1, 133.1, 129.6, 126.5, 124.5,
6
1
23.8, 120.4, 115.2, 112.3, 111.3, 59.1, 45.9, 31.8, 29.6, 26.7, 24.5, 24.4. Found C, 76.07;
H, 6.82; N, 11.68. C H N O·0.2H O requires C, 76.09; H, 7.05; N, 11.57%. 96.9% at
2
3
25
3
2
UV220 nm and 96.7% purity at UV254 nm based on isocratic HPLC (t = 2.31 min,
R
CH CN/water 40/60).
3
Synthesis of
2
,2,4,4-Tetramethyl-6-(pyrazolo[1,5-a]pyridin-4-yl)-2,3,4,7,8,9-hexahydro-1H-cyclope
nta[h]quinolin-3-one (12f). With a method using pyrazolo[1,5ꢀa]pyridynꢀ4ꢀyl
trifluoromethanesulfonate instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B,
+
compound 12f was obtained as a gray powder (14 mg, 24%). HRMSꢀESI m/z [M+H] calcd
1
for C H N O, 360.20704; found 360.20584. H NMR (300 MHz, DMSOꢀd )
δ
8.61 (d, J =
2
3
25
3
6
2
7
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Page 28 of 53
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1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
6
.8 Hz, 1H), 7.98 (d, J = 2.3Hz, 1H), 7.17 (s, 1H), 7.12 (d, J = 6.8 Hz, 1H), 6.93 (dd, J =
.8, 6.8 Hz, 1H), 6.42 (d, J = 2.3 Hz, 1H), 5.38 (s, 1H), 2.79 ꢀ 2.87 (m, 4H), 1.99 ꢀ 2.08 (m,
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
3
2H), 1.37 (s, 6H), 1.30 (s, 6H). C NMR (101 MHz, DMSOꢀd ) δ 214.8, 141.5, 141.3,
6
139.6, 139.0, 131.4, 129.6, 126.8, 126.3, 124.1, 123.6, 122.4, 112.0, 97.0, 59.2, 45.9, 32.3,
29.6, 26.7, 24.7, 24.5. Found C, 72.67; H, 6.75; N, 15.27. C H N O·0.2H O requires C,
22
24
4
2
7
2.58; H, 6.76; N, 15.39%. 99.5% purity at UV220 and 98.2% purity at UV254 nm based
on isocratic HPLC (t = 3.33 min, CH CN/water 65/35).
R
3
Synthesis of
-(Imidazo[1,2-a]pyrazin-5-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cyclopen
6
ta[h]quinolin-3-one (12g). With a method using 5ꢀchloroꢀimidazo[1,2ꢀa]pyrazine instead
of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12g was obtained as a
+
white powder (22 mg, 37%). HRMSꢀESI m/z [M+H] calcd for C H N O, 361.20229;
2
2
24
4
1
found 361.20083. H NMR (300 MHz, DMSOꢀd )
δ
9.14 (s, 1H), 7.99 (s, 1H), 7.97 (d, J =
6
1.1 Hz, 1H), 7.87 (s, 1H), 7.27 (s, 1H), 5.68 (s, 1H), 2.87 (t, J = 7.5 Hz, 2H), 2.71 (t, J = 7.5
1
3
Hz, 2H), 2.00 ꢀ 2.10 (m, 2H), 1.37 (s, 6H), 1.32 (s, 6H). C NMR (101 MHz, DMSOꢀd ) δ
6
214.4, 142.5, 140.7, 140.7, 140.6, 135.4, 131.6, 129.8, 128.4, 126.6, 124.3, 117.0, 112.8,
5
9.1, 45.9, 31.8, 29.6, 26.7, 24.5, 24.5. 98.7% purity at UV220 nm and 99.0% purity at
2
8
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Journal of Medicinal Chemistry
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UV254 nm based on isocratic HPLC (t = 2.76 min, CH CN/water 40/60).
R
3
Synthesis of
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
6-(1,2,4-Triazolo[4,3-a]pyridin-8-yl)-2,2,4,4-tetramethyl-2,3,4,7,8,9-hexahydro-1H-cycl
openta[h]quinolin-3-one (12i). With a method using 8ꢀbromoꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine
instead of 5ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12i was
+
obtained as a white powder (17 mg, 31%). HRMSꢀESI m/z [M+H] calcd for C H N O,
2
2
24
4
1
3
61.20229; found 361.20083. H NMR (400 MHz, DMSOꢀd )
δ
9.32 (s, 1H) 8.53 (dd, J =
6
6
.74, 0.96 Hz, 1H), 7.39 (s, 1H), 7.31 (d, J = 6.33 Hz, 1H), 7.05 (t, J = 6.74 Hz, 1H), 5.38
13
(
brs, 1H), 2.74 ꢀ 2.97 (m, 4H), 2.02 (m, 2H), 1.32 ꢀ 1.47 (m, 6H), 1.30 (s, 6H). C NMR
(
101 MHz, DMSOꢀd ) δ 214.8, 170.2, 148.0, 142.0, 139.3, 136.8, 129.2, 128.7, 125.9,
6
1
1
25.8, 125.0, 122.9, 122.5, 113.7, 79.1, 59.7, 59.2, 45.9, 32.8, 29.5, 26.7, 24.7, 24.4, 20.7,
4.0. 98.3% purity at UV220 nm and 98.7% purity at UV254 nm based on isocratic HPLC
(
t = 2.55 min, CH CN/water 40/60).
R 3
Synthesis of
2,2,4,4-Tetramethyl-6-(quinolin-4-yl)-2,3,4,7,8,9-hexahydro-1H-cyclopenta[h]quinolin-
3-one (12j). With a method using 4ꢀchloroquinoline instead of
5
ꢀchloroꢀ1,2,4ꢀtriazolo[4,3ꢀa]pyridine in the method B, compound 12j was obtained (12 mg,
2
9
ACS Paragon Plus Environment