5-HT7 Receptor Antagonists with an Unprecedented Selectivity Profile

Full text of DOI:10.1002/cmdc.201800026

Accepted Article
Title: Novel 5-HT7 antagonists, with an unprecedented selectivity
profile
Authors: Ali Ates, Pierre Burssens, Olivier Lorthioir, Patrick Lo Brutto,
Gwenael Dehon, Jean Keyaerts, Francis Coloretti, Lallemand
Bénédicte, Verbois Valérie, Gillard Michel, and Vermeiren
Céline
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content of this Accepted Article.
To be cited as: ChemMedChem 10.1002/cmdc.201800026
Link to VoR: http://dx.doi.org/10.1002/cmdc.201800026
A Journal of
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10.1002/cmdc.201800026
ChemMedChem
COMMUNICATIONS
Finally, regarding the large diversity of published 5-HT7 antagonist
ligands, only limited data is available regarding the selectivity
profile. From the above, it transpires that additional 5-HT7 antagonist
ligands exhibiting a high selectivity profile toward the 5-HT7
receptors are needed to explore 5-HT7 receptor pharmacology as
well as to progress new compounds to the clinic.
Our medicinal chemistry program was therefore aimed at the
identification of novel chemical series, targeting the 5-HT7 receptor
and resulted in the identification of tool compounds displaying high
selectivity which were suitable for in vivo profiling.
DOI: 10.1002/cmdc.200((will be filled in by the editorial staff))
Novel 5-HT7 antagonists, with an
unprecedented selectivity profile
Ali Ates,[a]* Burssens Pierre,[a] Lorthioir Olivier,[a] Lo Brutto
Patrick,[a] Dehon Gwenael,[a] Keyaerts Jean,[a] Coloretti
Francis,[a] Bénédicte Lallemand,[a] Valérie Verbois,[a]
Michel Gillard,[a] and Céline Vermeiren[a]
The decahydroisoquinoline (DHIQ) starting hit 1 (Fig. 2), was
identified by a High throughput screening campaign of the UCB
library (~150000 cpds) on the recombinant human 5-HT7 receptor
using a competition binding assay.
The serotonin 5-HT7 receptor is the last recently identified subtype
of the serotonin receptor family. The 5-HT7 receptor was discovered
in 1993, and subsequently cloned from a number of species such
[1]
Decahydroisoquinoline (DHIQ)
as rat, mouse or human and many more since then.
The
H
discovery that several marketed antipsychotics as well as
antidepressant drugs exhibited affinities for this receptor triggered
many academic and industrial research projects around the world.
Today, after more than two decades of research, progress has been
made in both the understanding of biology and pharmacology of the
peripheral and central 5HT7 receptors. Besides depression,
potential applications in cognition, migraine as well as modulation of
sleep architecture and circadian rhythm have been reported. [2]
In parallel to the progress made in biology and pharmacology, a
huge diversity of ligands showing high affinity for this receptor have
been reported in the literature. [3] Amongst them, SB-269970 (Fig.
1) reported 17 years ago occupies a cardinal position. [4] Indeed, its
high affinity toward the 5-HT7 receptor (5-HT7 pKi = 9.1), coupled to
its 50-fold minimal selectivity over the entire serotonin receptor
family as well as a range of GPCRs, ion channels and enzymes
propelled it to become the reference tool compound in the field
(see Table 1 and supporting information). It is noteworthy that
despite its poor pharmacokinetic profile (high rodent blood
clearance and no oral bioavailability), this compound is still today
the only compound used to assess the 5-HT7 pharmacology
worldwide. More recently, the structure of JNJ18038683 (Fig. 1), a
5-HT7 antagonist clinical candidate from Johnson & Johnson was
disclosed in the literature, together with its selectivity profile and
clinical data in major depressive disorder. Its selectivity for 5-HT7 is
limited by high affinity toward other receptors such as 5-HT6 (10-fold
selectivity) and adrenergic α1 (15-fold selectivity). [5]
N
H
O
N
1
5-HT7 pKi: 7.1
MW: 342.5
OMe
Figure 2: Initial hit
The synthesis of target derivatives 1 started with the reduction of
commercially available (S) or (R) pyrroglutamic esters into the
corresponding (S) or (R) alcohols 4 (Scheme 1). N-arylation using
copper catalyst in dioxane with potassium phosphate, followed by
the activation of the alcohol moiety into a tosylate intermediate,
yielded targeted compounds 6 after substitution with the selected
amine (R1R2NH) in acetonitrile/potassium carbonate. An alternative
synthetic route from alcohol 4 started first with the conversion to the
tosylate intermediate 7 in dichloromethane/triethylamine followed by
the substitution with the selected amine (R1R2NH) in
acetonitrile/potassium carbonate. Targeted molecules 6 were then
obtained by arylation of the N-lactam nitrogen atom of intermediate
8 (Scheme 1).
O
H O
H O
O
O
O
(a)
(b)
N
H
N
H
N
O
4
5
2
(d)
(b)
(S) Pyrroglutamic ester
(c)
Cl
R1
R3
N
R2
N
(d)
O
N
SO
N
N
H
O
2
N
6
O
N
N
R1
O
H
TsO
N
O
H
R2
(c)
R3
3
O
O
N
H
N
H
(R) Pyrroglutamic ester
JNJ-18038683
SB-269970
7
8
(a) NaBH4, EtOH (99%); (b) Ar-Br, CuI/diamine, K3PO4, Dioxane (75-90%); (c) R1R2NH, K2CO3,
MeCN (45-92%); (d) TsCl, TEA, DMAP, CH2Cl2 (65-98%); Similar results were obtained with the
(R) Pyrroglutamic ester.
Figure 1: Chemical structure of SB-269970 and JNJ18038683
Scheme 1
Table 1: SB-269970 binding affinities (pKi) for the 5-HT7D and off target receptors. Data
are the means of separate experiments.
Selectivity
(log)
Binding affinities to the 5-HT7 receptor are listed in Table 2. The
tetrahydroisoquinoline (THIQ) analogue 9 is a good surrogate of the
quite complex trans-decahydroisoquinoline (DHIQ) motif present in
the starting hit 1. The replacement of the methoxy group of
compound 9 by a chlorine atom was well tolerated (compound 10).
5-HT7D
α2C
α2A
α1A
5-HT1A
5-HT5A
Sigma-1
9.1
5.7
5.7
6.7
6.0
7.5
6.8
1.6
1
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10.1002/cmdc.201800026
ChemMedChem
However the removal of the aromatic ring of the THIQ moiety, was
not allowed, compound 11 (Table 2). The (S) configuration showed
much better activity than the corresponding (R) configuration
(compare compounds 10 and 12). The ring contraction leading to
Unfortunately, the compounds with higher affinity listed in Table 2
displayed a max selectivity of 32-fold (1.5-1.6 log). Their selectivity
profiles were limited by residual affinity toward other receptors such
as the adrenergic α2C or 5-HT1A receptors.
the isoindoline structure 13 was also detrimental to the 5-HT7 In order to try to further increase the potency toward the 5-HT7
affinity. A methoxy scan around the aromatic ring of the THIQ receptor, we decided to increase the flexibility of the scaffold by
moiety revealed that a methoxy in position-8 was most favorable for varying the number of methylene units between the nitrogen atom
the 5-HT7 binding affinities (see compounds 14 to 17). Finally,
replacing the methoxy group of compound 17 by an amide group
of the THIQ and the pyrrolidone ring system (n = 1 and 2, Scheme
2). Starting from both the optically pure (R) or (S) tosylate
led to compound 18 that displayed also acceptable affinity and intermediates 7 (Scheme 2), the homologated alkyl chain analogues
selectivity for the 5-HT7 receptor.
(n=1, Scheme 2) were synthesized by substitution of the tosylate
group by potassium cyanide in acetonitrile followed by acid-chloride
hydrolysis in ethanol to give the corresponding ethyl esters 19.
Optically pure alcohol 20 was obtained by reduction of ester 19 with
sodium borohydride in ethanol. The corresponding three methylene
unit alcohols 23 was obtained by reacting the tosylate intermediate
7 with an excess of allyl-magnesium bromide in tetrahydrofurane to
yield 22, followed by ozonolysis and reduction in ethanol. Targeted
compounds 21 (n = 1 or 2) were obtained from alcohols 20 or 23
respectively (Scheme 2).
Table 2: Compound binding affinities (pKi) to the 5-HT7D receptor and off target
receptor (nt stands for not tested). Data are the means of separate experiments.
Selectivity
Cpd/Structure
5-HT7D
α2C
α2A
α1
5-HT1A
(log)
1
H
N
H
O
N
7.1
6.7
5.8
5.3
5.0
0.4
OMe
9
O
N
O
N
TsO
6.6
nt
nt
nt
nt
nt
<5.0
<5.0
<5.0
1.6
EtO
O
O
O
(b), (a)
(d)
N
H
N
H
N
H
19
20
7
22
23
OMe
(c)
(e)
Or
10
11
12
13
H O
TsO
H O
N
O
O
O
O
N
N
H
N
H
N
H
6.8
nt
nt
nt
/
/
/
/
7
R1
Cl
(CH2)n
N
O
N
(f), (g), (h)
(f), (g), (h)
N
21
R2
O
<5.0
N
nt
nt
nt
(a) KCN, KI, MeCN, reflux (93%); (b) i. HCl(g), EtOH, 65°C; ii. NaHCO3; iii. Toluene,
reflux (77%); (c) NaBH4, EtOH (99%); (d) Allyl-MgBr, THF, -30°C (69%); (e) i O3,
EtOH, -70°C; ii NaBH4, EtOH -70°C (75%); (f) Ar-Br, CuI/diamine, K3PO4, Dioxane;
(g) TsCl, TEA, DMAP, CH2Cl2; (h) THIQ, K2CO3, MeCN
Cl
N
O
N
<5.0
<5.0
nt
nt
nt
Scheme 2
Cl
As illustrated in Table 3, the opposite absolute configuration of the
pyrrolidone stereochemistry from the compounds in Table 2 gave
the best affinities for 5-HT7 receptor when moving to two or three
methylene unit linker (match pair compounds 24/25 and 30/31 to be
compared in Table 3). Importantly, compounds bearing a propyl-
linker produced a dramatic increase in 5-HT7 binding affinity as
exemplified by compounds 28-30 (5-HT7 pKi > 9.0, Table 3).
N
O
N
nt
nt
nt
Cl
14
MeO
N
O
N
<5.0
6.5
nt
nt
nt
nt
nt
nt
nt
nt
/
/
With the exception of compound 27, the selectivity profiles of the
most potent compounds displayed in Table 3 were rather low and
limited by high affinity toward receptors such as the 5-HT1A or the
adrenergic α2C receptor. The poor selectivity profile of compounds
28 to 31 (Table 3) could be explained by the high degree of
conformational freedom which would allow compounds to sample
different low energy conformations thus permitting the binding with
various receptors.
Cl
15
MeO
N
O
N
Cl
16
OMe
N
7.4
6.8
6.3
5.5
5.3
0.6
O
N
Cl
17
N
O
MeO
N
8.0
7.8
7.5
6.3
7.1
5.6
6.6
6.2
7.4
6.2
0.5
1.5
Cl
18
N
O
N
H
2N
O
Cl
2
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10.1002/cmdc.201800026
ChemMedChem
Table 3: Compound binding affinities (pKi) to the 5-HT7D receptor and off target
receptor (nt stands for not tested). Data are the means of separate experiments.
Selectivity
block. Finally displacement of the tosyslate group intermediate 37
by THIQ derivatives gave the title compounds 38 (Scheme 4).
Cpd/Structure
5-HT7D
α2C
α2A
α1
5-HT1A
(Log)
O
O
I
N
N
24
MeO
MeO
H O
(a)
(b)
N
O
N
O
O
6.7
nt
6.7
5.9
5.7
0
34
35
36
Cl
O
O
N
N
(c)
(d)
25
26
TsO
N
R1
N
O
N
38
37
7.4
7.6
7.7
7.5
7.1
7.3
6.2
6.1
6.0
7.2
-0.3
0.1
(a) CuI, K3PO4, Pyrroliodone, 1,2-Cyclohexyl-diamine, Dioxane (55%); (b) LiBH4, THF (94%);
(c) NMI, TsCl, DCM (86%); (d) THIQ, MeCN, K2CO3, 85°C (55-95%)
Cl
OMe
Scheme 4
N
O
N
The corresponding piperidone derivatives 43, were prepared
according to Scheme 5. Aniline 39 was amidated using Ʊ-bromo-
Cl
27
chloro-pentenoate, followed by
a ring closure reaction with
O
N
H
2
potassium tert-butoxyde to furnish intermediate 41 in a good overall
yield of 71%. Conversion to the tosylate derivative yielded the
building block 42, precursor of the titled compounds 43 (Scheme 5).
N
O
N
8.0
9.1
6.6
9.1
6.2
8.2
5.4
7.1
6.3
8.4
1.4
Cl
28
29
N
H
2
Br
H N
O
N
O
N
H O
H O
H O
(a)
(b)
O
N
0
39
40
41
Cl
N
O
N
O
TsO
N
(c)
(d)
N
R1
O
O
N
9.2
9.5
8.6
9.4
8.0
8.7
7.3
8.3
9.7
9.7
-0.5
-0.2
N
H
2
42
43
(a) 5-Bromopentanoyl chloride, Et3N, DCM (100%); (b) tBuOK, THF (71%); TsCl, DMAP,
Et3N, DCM (88%); R1R2NH, K2CO3, MeCN (55-75%).
Cl
30
31
N
Scheme 5
MeO
O
N
Among the diversity of potential THIQ derivatives, that could be
introduced to building blocks 37 and 42 (Scheme 4 and 5), we
decided to focus our initial structure activity relationship (SAR)
investigation around the derivatives already used in the previous
section (Table 3). As can be seen from Table 4, with the
pyrrolidone ring system (n = 1), similar SAR was obtained. Highest
Cl
N
MeO
O
N
8.2
8.5
8.4
7.7
8.1
-0.3
Cl
affinities
tetrahydroisoquinoline
were
obtained
48
with
or
the
the
8-Methoxy-1,2,3,4-
8-amide-1,2,3,4-
In an attempt to marry, high affinity (5-HT7 pKi > 8.0) with good
selectivity (> 30-fold), we decided to limit the flexibility of
compounds. Thus we limited the linker length to two methylene unit
(ethyl) (structure 32, Scheme 3) whilst simultaneously shifting the
alkyl chain bearing the THIQ moiety to the ortho position of the
aromatic ring linked to the pyrrolidone system (structure 33,
Scheme 3).
tetrahydroisoquinoline 49. However, with the piperidone ring system
(n = 2), affinities were higher or equal to the corresponding
pyrrolidine ring analogues (n = 1), eg. compare compounds 44 and
50 in Table 4. Again the highest potency was observed for the 8-
Methoxy-1,2,3,4-tetrahydroisoquinoline derivative, ie. 51 (n = 2,
Table 4).
R2
N
O
O
N
N
N
R2
R1
R1
32
33
Scheme 3
Synthetic access to analogues of 33 started with an Ullman type
coupling of the Iodo-aryl-acetic ester 34 with pyrrolidone to yield
intermediate 35 (Scheme 4). Reduction of the ester 35 to the
corresponding alcohol 36 and subsequent conversion to the
tosylate derivative yielded compound 37 as a versatile building
3
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10.1002/cmdc.201800026
ChemMedChem
( )n
O
N
In summary, through a rational SAR study based on compound 1
(Figure 2), we have identified a series of novel 5-HT7 antagonists
displaying unprecedented selectivity for 5-HT7 receptor. We believe
these selective 5-HT7 antagonists will serve as valuable tools to aid
the understanding of the 5-HT7 receptor pharmacology and
constitute outstanding starting points for lead optimization.
R1
N
R2
Table 4: Compound binding affinities (pKi) to the 5-HT7D receptor and off
target receptor (nt stands for not tested). Data are the means of separate experiments.
Selectivity
(Log)
R1NR2
n
5-HT7D
α2C
α2A
α1A
5-HT1A
5-HT5A
Acknowledgements
44
45
The authors would like to thank Ms. Isabelle Jacques, Mr. Philippe
Motte for their technical expertise in in-vitro screening, Ms.
Géraldine Longfils, Dr. Benoit Mathieu and Ms. Ariane Descamps
for physchem support and Ms. Aurélie Bremaud, Mr. Rudi Jacqmin;
Mr. Didier Sénéchal, Mr. Marc Van Thuyne and Dr. Véronique
Pinilla for column chromatography support. Dr R. Dieden, Mr A.
Fauconnier, Mr J. Claessens, and Mrs C. Derwa for analytical
assistance; Dr. B. Barnaby for in vitro PK. This work was financed in
part by the Walloon Region (Belgium) under conventions n°5708 &
6272.
1
7.4
6.6
6.8
5.8
<5.0
nt
0.6
0.2
N
OMe
1
1
7.4
6.1
6.8
nt
7.2
6.0
nt
6.3
nt
nt
N
46
O
nt
nt
/
N
47
N
1
6.9
6.3
5.7
6.2
6.0
nt
0.6
O
48
Keywords: selective, serotonin, 5-HT7 receptor, antagonist
N
1
1
8.3
7.9
7.2
5.6
6.6
<5
6.1
<5
6.3
5.8
nt
1.1
0.7
OMe
49
N
7.2
O
N H
2
50
2
2
8.5
9.0
6.0
6.8
<5
<5
<5
6.4
7.4
2.1
1.6
N
51
6.1
5.8
6.5
N
OMe
52
N
2
2
8.1
8.3
<5
<5
<5
<5
<5
<5
<5
<5
6.5
5.5
1.6
2.8
O
N H
2
53
N
NC
Much to our delight, the selectivity profile of compounds with best
affinities (48 to 53) was also very attractive and to the best of our
knowledge, unprecedented in the literature. Indeed, the selectivity
profile was as high as 630-fold in the case of compound 53 and
systematically higher or equal to 40-fold in the case of compounds
50, 51 and 52 (Table 4). Amongst the GPCRs, enzymes and ion
channels screened, the 5-HT5A receptor was systematically the off-
target which limited the selectivity profile (compounds 49 to 53,
Table 4). Thus, we describe compound 49 as a dual 5-HT7D/5-HT5A
ligand and compounds 50 to 53 as selective 5-HT7 ligands (for
broader profiling see supporting information).
Compounds 50 to 53 demonstrated antagonist properties in a 5-
HT7D assay stimulated with 5-CT (Table 5 and experimental part).
Table 5: 5-HT7 antagonism: cell based cAMP functional assay.
Data are the means of separate experiments.
Cpd
pIC50 cAMP
50
6.8
8.7
7.5
8.1
9.0
51
52
53
SB-269970
Compounds 50 to 53 were tested up to 10 µM for agonism
and no activation of 5-HT7 receptor was observed above 5%.
4
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10.1002/cmdc.201800026
ChemMedChem
Experimental part
5 H), 2.35 (m, 2 H), 1.81 (m, 1 H), 1.61 (s, 2 H), 1.39 (d, J = 8.3 Hz,
6- 1 H), 1.07 (m, 2 H). LC-MS (100%) MH+ 412
5-(R1R2aminometyl)-1-aryl-pyrrolidin-2-one
(R1R2aminometyl)-1-aryl-piperidin-2-one 21.
6
and
1-[2-[2-(R1-3,4-dihydro-1H-isoquinolin-2-yl)ethyl]phenyl]pyrrolidin-2-
one 38.
To a solution of the alcohol (0.26 mol) and halo-aryl (0.26 mol)
dissolved in dioxane (750mL) was added K3PO4 (0.65 mol) at room
temperature. The reaction mixture was heated at 100°C followed by
the addition of 1,2-diaminocyclohexane (0.052 mol) and copper(I)-
iodide (0.026 mol). The reaction mixture was heated overnight at
100°C. Salts were filtered off, volatiles were removed under vacuo
and the crude mixture was purified by column chromatography to
afford intermediate compounds 5-(hydroxyalkyl)-1-aryl-pyrrolidin-2-
one or 6-(hydroxyalkyl)-1-aryl-piperidin-2-one in good yield (75-
90%). To a solution of 5-(hydroxyalkyl)-1-aryl-pyrrolidin-2-one or 6-
(hydroxyalkyl)-1-aryl-piperidine-2-one from above (44 mmol)
dissolved in dichloromethane (150 mL) was added N-
methylimidazole (255 mmol) at 0°C. The reaction mixture was
stirred at 0°C during 1h. 4-methylbenzenesulfonyl chloride (TsCl, 52
mmol) dissolved in dichloromethane (200 mL) was added dropwise
at 0°C and the reaction mixture was stirred overnight at room
temperature. The organic layer was successively washed with water
(200 mL), aqueous HCl (2.5 M, 200 mL) and water (200 mL). The
organic layer was dried over MgSO4, the solid was filtered off and
volatiles were removed under vacuo. The residue was purified by
column chromatography to afford the tosylates intermediates (65-
98% yield). The tosylate (1 mmol) and the selected amine derivative
(1 mmol) were dissolved in CH3CN (5 mL) and K2CO3 (3 mmol) was
added at room temperature. The reaction mixture was stirred
overnight at 85°C. Salts were filtered off, volatiles were removed
under vacuum and the residue was purified by column
chromatography to afford compounds 6 or 21 (45-92%).
To a solution of pyrrolidine-2-one (1 mmol) and Iodo-aryl 34 (1 eq)
dissolved in dioxane (10mL) was added K3PO4 (3 eq) at room
temperature, followed by the addition of 1,2-diaminocyclohexane
(0.2 eq) and copper(I)-iodide (0.1 eq). The reaction mixture was
heated overnight at 65°C. Salts were filtered off, volatiles were
removed under vacuo and the crude mixture was purified by column
chromatography to afford 35 (55%), LC-MS (98%) MH+ 234
To a solution of 35 (6.27g, 26.88 mmol) dissolved in THF (250mL)
was added Lithium borohydride (4 eq, 2.27g) portionwise at 0°C,
reaction mixture was then stirred overnight at room temperature.
Reaction mixture was poured on crushed ice (250g) followed by
extraction with dichloromethane (3x100mL). The organic layer was
dried over MgSO4, the solid was filtered off and volatiles were
removed under vacuo to afford compound 36 (60%), LC-MS (96%)
MH+ 206
To a solution of 36 from above (1 eq) dissolved in dichloromethane
was added N-methylimidazole (5 eq) at 0°C. The reaction mixture
was stirred at 0°C during 1 hour. 4-methylbenzenesulfonyl chloride
(TsCl, 1.1 eq) dissolved in dichloromethane was added dropwise at
0°C and the reaction mixture was stirred overnight at room
temperature. The organic layer was successively washed with water
(20 mL), aqueous HCl (2.5 M, 20 mL) and water (20 mL). The
organic layer was dried over MgSO4, the solid was filtered off and
volatiles were removed under vacuo. The residue was purified by
column chromatography to afford 37 (86%), LC-MS (98%) MH+ 360.
The tosylate 37 (1 mmol) and the selected THIQ-amine derivative
(1 mmol) were dissolved in CH3CN (5 mL) and K2CO3 (3 mmol) was
added at room temperature. The reaction mixture was stirred
overnight at 85°C. Salts were filtered off, volatiles were removed
under vacuum and the residue was purified by column
chromatography to afford compounds 38 (55-95%).
(5S)-1-(4-chlorophenyl)-5-[(5-methoxy-3,4-dihydro-1H-isoquinolin-2-
yl)methyl]pyrrolidin-2-one 16,
1H NMR (400 MHz, DMSO-d6) δ 7.61 (d, J = 8.8 Hz, 2 H), 7.44 (d, J
= 8.8 Hz, 2 H), 7.12 (t, J = 8.0 Hz, 1 H), 6.79 (d, J = 8.0 Hz, 1 H),
6.65 (d, J = 7.5 Hz, 1 H), 4.68 (t, J = 8.0 Hz, 2 H), 3.75 (m, 6 H),
2.91 (m, 1 H), 2.77 (m, 2 H), 2.65 (m, 4 H), 2.33 (m, 2 H), 2.05 (m, 1
H). LC-MS (97%) MH+ 371
2-[2-[2-(2-oxopyrrolidin-1-yl)phenyl]ethyl]-3,4-dihydro-1H-
isoquinoline-8-carboxamide 49,
1H NMR (400 MHz, DMSO-d6) δ 7.92 (s, 1 H), 7.47 (s, 1 H), 7.41
(5S)-1-(4-chlorophenyl)-5-[(8-methoxy-3,4-dihydro-1H-isoquinolin-
2-yl)methyl]pyrrolidin-2-one 17,
1H NMR (400 MHz, DMSO-d6) δ 7.59 (m, 2 H), 7.45 (d, J = 8.8 Hz,
2 H), 7.12 (t, J = 7.8 Hz, 1 H), 6.77 (d, J = 8.0 Hz, 1 H), 6.70 (d, J =
7.5 Hz, 1 H), 3.76 (s, 3 H), 3.62 (s, 2 H), 2.75 (m, 6 H), 2.31 (m, 3
H), 2.07 (m, 1 H). LC-MS (99%) MH+ 371
(dd, J = 9.0, 4.0 Hz, 2 H), 7.32 (m, 4 H), 7.27 (d, J = 3.8 Hz, 1 H),
4.38 (s, 2 H), 3.71 (t, J = 6.8 Hz, 2 H), 3.33 (s, 2 H), 3.21 (m, 2 H),
3.08 (t, J = 5.5 Hz, 2 H), 2.89 (m, 2 H), 2.16 (m, 2 H). LC-MS
(100%) MH+ 364
1-[2-[2-(3,4-dihydro-1H-isoquinolin-2-yl)ethyl]phenyl]piperidin-2-one
43.
2-[[(2S)-1-(4-chlorophenyl)-5-oxo-pyrrolidin-2-yl]methyl]-3,4-dihydro-
1H-isoquinoline-8-carboxamide 18,
A solution of 2-(2-aminophenyl)ethanol 39 (450 g, 3.28 mol, 1 eq)
and triethylamine (332 g, 3.28 mol, 1 eq) in dichloromethane (2 L)
was cooled at -5 °C and bromovalerylchloride (654 g, 3.28 mol, 1
eq) in dichloromethane (2 L) was added dropwise without
exceeding 0°C. The organic phase was washed with HCI 1N (4x2 L)
and brine (1x2 L). The aqueous layer was extracted with
dichloromethane (1x2 L). The combined organic layers was dried
over MgSO4, filtered and evaporated under vacuum to afford 1008 g
of 5-bromo-N-[2-(2-hydroxyethyl)phenyl]pentanamide 40 (100%),
LC-MS (96%) MH+ 300
A solution of 5-bromo-N-[2-(2-hydroxyethyl)phenyl]pentanamide 40
(938 g, 3.28 mol, 1 eq) in THF (6 L) was cooled at -5 °C. Potassium
tert-butoxide (552 g, 4.92 mol, 1.5 eq) was added portion-wise,
without exceeding 0°C, then the mixture was warmed up to room
temperature. The reaction mixture was washed with a saturated
aqueous solution of NaCI (3x2 L). The combined aqueous layers
1H NMR (400 MHz, DMSO-d6) δ 7.69 (s, 1H), 7.60 – 7.53 (m, 2H),
7.46 – 7.38 (m, 2H), 7.30 (s, 1H), 7.25 – 7.09 (m, 3H), 4.54 (tt, J =
7.5, 3.4 Hz, 1H), 3.68 (s, 2H), 2.84 – 2.49 (m, 7H), 2.41 – 2.16 (m,
2H), 2.05 – 1.93 (m, 1H). LC-MS (99%) MH+ 384
2-[2-[(2R)-1-(4-chlorophenyl)-5-oxo-pyrrolidin-2-yl]ethyl]-3,4-
dihydro-1H-isoquinoline-8-carboxamide 27,
1H NMR (400 MHz, DMSO-d6) δ 7.41 (m, 9 H), 4.42 (d, J = 0.8 Hz,
1 H), 4.26 (s, 2 H), 3.18 (m), 3.00 (s, 3 H), 2.60 (m, 3 H), 2.42 (m, 1
H), 2.27 (m, 1 H), 1.98 (d, J = 1.0 Hz, 1 H), 1.81 (m, 2 H). LC-MS
(99%) MH+ 398
2-[3-[(2S)-1-(4-chlorophenyl)-5-oxo-pyrrolidin-2-yl]propyl]-3,4-
dihydro-1H-isoquinoline-8-carboxamide 29,
1H NMR (400 MHz, DMSO-d6) δ 7.45 (m, 7 H), 4.36 (m, 2 H), 4.19
(dd, J = 1.3, 0.8 Hz, 3 H), 3.41 (dq, J = 22.8, 7.0 Hz, 2 H), 3.01 (m,
5
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10.1002/cmdc.201800026
ChemMedChem
was extracted with dichloromethane (2x2 L), the combined organic
layers was dried over MgSO4, filtered and concentrated under
reduced pressure. The residue was recrystallized from tert-butyl
Cheng and Prusoff (1973) [6]. Reference 5-HT7 ligand was tested in
each experiment for validation.
methyl
ether
to
afford
510
g
of
1-
[2-(2- 5-HT7 cAMP Functional assay: 5-HT7 receptor is coupled to Gs type
hydroxyethyl)phenyl]piperidin-2-one 41 (71 %), LC-MS (100%) MH+ G-protein. It’s activation by an agonist like serotonin or 5-CT
220
induces an increase in intracellular cAMP concentration. In the
presence of 5-HT7 antagonist, intracellular cAMP concentration
Dimethylaminopyridine (1.83 g, 15 mmol, 0.05 eq) and triethylamine
(63.5 ml, 450 mmol, 1.5 eq) were added to a solution of 1-[2-(2- induced by the agonist is blocked. In the present study, the agonist
hydroxyethyl)phenyl]piperidin-2-one 41 (65.7 g, 300 mmol, 1 eq) in
dichloromethane (250 mL) at 0°C. The mixture was stirred at 0°C
for 15 minutes, then a solution of 4-toluenesulfonyl chloride (63 g,
330 mmol, 1.1 eq) in dichloromethane (250 mL) was added
dropwise. The reaction mixture was then warmed up to room
temperature and stirred overnight. The reaction mixture was
washed with water, 1N HCI, then dried over MgSO4, filtered and
evaporated under vacuum. The residue was purified by
chromatography over silicagel (gradient: CH2Cl2/MeOH from 100/0
versus antagonist nature of the test compounds was assessed in
each experiment by measuring intracellular cAMP concentration in
the absence and presence of 5-CT (EC80), respectively in HEK293
Flp-In cells expressing human recombinant 5-HT7D receptor. GPCR
cAMP HTRF assay kit from Cisbio (Codolet, France) was used to
measure cAMP intracellular concentration [7]. Reference agonist and
antagonist potencies were assessed in each experiment for
validation.
Selectivity profiling: Compound selectivity for 5-HT7 receptor was
to 98/2) to afford 99 g of 2-[2-(2-oxopiperidin-1-yl)phenyl]ethyl 4- assessed as compared to a broad panel of related and unrelated
methylbenzenesulfonate 42 (88 %), LC-MS (96%) MH+ 374
receptors, enzymes, transporters and ion channels. Selectivity
Selected R1-THIQ (2 mmol, 1 eq) and K2CO3 (6 mmol, 3 eq) were profiling of 10 µM compound was performed in duplicate jointly at
added to a solution of 2-[2-(2-oxopiperidin-1- yl)phenyl]ethyl 4-
methylbenzenesulfonate 42 (2 mmol, 1 eq) in acetonitrile (10 mL).
The reaction mixture was stirred at 85°C overnight, then filtered and
the filtrate was condensed under reduced pressure. The residue
was purified by basic reverse phase chromatography over silicagel
(gradient CH3CN/H2O/NH4OH from 50/50/0.1 to 80/20/0.1) to
afford 43 as a free base. Oxalic acid (1 eq) was added to the
residue dissolved in diethylether. The precipitate obtained was
filtered and dried under vacuum to afford 43 (55 %).
UCB BioPharma (Braine-l’Alleud, Belgium) and at CEREP (Celle-
l’Evescault, France). For compounds inhibiting off targets above
80% of inhibition at 10 µM, affinity was measured testing
compounds at increasing concentrations in competitive binding
assays.
References
[1] (a) Ruat, E. Traiffort, R. Leurs, J. Tardivel-Lacombe, J. Diaz,
J.M. Arrang, J.C. Schwartz, Proc Natl Acad Sci U S A. 1993, 90,
8547-51; (b) T. W. Lovenberg, B. M. Baron, L. Lecea, J. D. Miller,
R. A. Prosser, M. A. Rea, P. E. Foye, M. Racke, A. L. Slone, B. W.
Siegel, P. E. Danielson, J. G. Sutcliffe, M. G. Erlander, Neuron.
1993, 11, 449-458; (c) J. L. Plassat, N. Amlaiky, R. Hen, Mol.
Pharmacol., 1993, 44, 229-236; (d) J. A. Bard, J. Zgombick, N.
Adham, P. Vaysse, T. A. Branchek, R. L. Weinshank, J. Biol.
Chem., 1993, 268, 23422-23426.
1-[2-[2-(3,4-dihydro-1H-isoquinolin-2-yl)ethyl]phenyl]piperidin-2-one
50,
1H NMR (400 MHz, DMSO-d6) δ 7,40 (m, 1 H), 7,32 (m, 2 H), 7,22
(m, 5 H), 4,28 (s, 2 H), 3,59 (m, 1 H), 3,35 (m, 3 H), 3,19 (m, 2 H),
3,05 (m, 2 H), 2,89 (m, 2 H), 2,41 (m, 2 H), 1,86 (m, 4 H). LC-MS
(100%) MH+ 335
[2] (a) A. Nikiforuk, CNS Drugs, 2015, 29, 265-275; (b) A.
J.Roberts; P. B. Hedlund, Hippocampus, 2012, 22(4), 762-771; (c)
A. Gasbarri, A. Pompili, Neurosciences, 2014, 25(3), 311-323; (d)
M. Leopoldo, E. Lacivita, F. Berard, R. Perrone, P.B. Hedlund,
2011, Pharmacol. Ther. 129, 120–148; (d) P. B. Hedlund,
Psychopharmacology, 2009, 206, 345-354.
[3] (a) V. Pittala, D. Pittala, Mini-Reviews in Medicinal Chemistry,
2011, 11(13), 1108-1121; (b) M. Leopoldo, Current Medicinal
Chemistry, 2004, 11(5), 629-661; (c) P. Raubo, M. S. Beer, P. A.
Hunt, I. T. Huscroft, C. London, J. A. Stanton, J. Kulagowski,
Bioorganic & Medicinal Chemistry Letters 2006, 16, 1255-1258.
1-[2-[2-(8-methoxy-3,4-dihydro-1H-isoquinolin-2-
yl)ethyl]phenyl]piperidin-2-one, 51,
1H NMR (400 MHz, DMSO-d6) δ 7.40 (dd, J = 6.3, 2.9 Hz, 1H), 7.35
– 7.27 (m, 2H), 7.28 – 7.18 (m, 2H), 6.85 (dd, J = 26.9, 7.9 Hz, 2H),
4.16 – 4.01 (m, 2H), 3.81 (s, 3H), 3.59 (dd, J = 11.8, 6.2 Hz, 1H),
3.32 (dt, J = 27.3, 5.2 Hz, 3H), 3.24 – 3.14 (m, 2H), 3.01 (s, 1H),
2.87 (dt, J = 10.6, 4.9 Hz, 2H), 2.48 – 2.30 (m, 3H), 1.93 – 1.84 (m,
4H). LC-MS (100%) MH+ 365
2-[2-[2-(2-oxo-1-piperidyl)phenyl]ethyl]-3,4-dihydro-1H-isoquinoline-
8-carboxamide 52,
1H NMR (400 MHz, DMSO-d6) δ 7.73 (s, 1 H), 7.37 (m, 1 H), 7.33
(s, 1 H), 7.20 (m, 6 H), 3.72 (d, J = 6.5 Hz, 2 H), 3.59 (m, 1 H), 3.33
(s, 1 H), 2.85 (t, J = 5.0 Hz, 2 H), 2.68 (m, 4 H), 2.59 (m, 2 H), 2.45
(m, 1 H), 2.35 (m, 1 H), 1.86 (m, 4 H). LC-MS (100%) MH+ 378
[4]
P. J. Lovell, S. M. Bromidge, S. Dabbs, D. M. Duckworth, I. T.
Forbes, A. J. Jennings, F. D. King, D. N. Middlemiss, S. K. Rahman,
D. V.Saunders, L. L. Collin, J. J. Hagan, J. Riley, D. R. Thomas,
Journal of Medicinal Chemistry, 2000, 43(3), 342-345.
[5] P.Bonaventure, C. Dugovic, M. Kramer, P. Boer, J. Singh, S.
Wilson, K. Bertelsen, J. Di, J. Shelton, L. Aluisio, L. Dvorak, I.
Fraser, B. Lord, D. Nepomuceno, A. Ahnaou, W. Drinkenburg, W.
2-[2-[2-(2-oxo-1-piperidyl)phenyl]ethyl]-3,4-dihydro-1H-isoquinoline-
7-carbonitrile 53,
1H NMR (400 MHz, DMSO-d6) δ 7.66 (m, 2 H), 7.39 (m, 2 H), 7.29
(m, 2 H), 7.20 (m, 1 H), 4.05 (s, 2 H), 3.59 (m, 1 H), 3.35 (m, 1 H),
3.13 (s, 2 H), 3.00 (m, 4 H), 2.79 (m, 2 H), 2.38 (m, 2 H), 1.88 (s, 4 Chai, C. Dvorak, S. Sands, N. Carruthers, and T. W. Lovenberg;
H). LC-MS (100%) MH+ 360
Journal of Pharmacology and Experimental Therapeutics,
2012, 342(2), 429-440.
5-HT7 competitive radioligand binding assay: Compound affinity
[6] Cheng Y, Prusoff WH. Relationship between the inhibition
(pIC50) for 5HT7 receptor was assessed in duplicate by competition
constant (K1) and the concentration of inhibitor which causes 50 per
against [³H]5-Carboxyamidotryptamine (5-CT) on HEK293 Flp-In
cent inhibition (I50) of an enzymatic reaction. Biochem Pharmacol.
cell membranes expressing human 5-HT7D receptor. [³H]5-CT KD
1973 Dec 1;22(23):3099-108
and radioligand test concentration were of 0.10 ± 0.02 and 0.36 ±
[7] Degorce F, Card A, Soh S, Trinquet E, Knapik GP, Xie B
0.03 nM, respectively. pIC50 were corrected to pKi according to
HTRF: A technology tailored for drug discovery - a review of
6
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10.1002/cmdc.201800026
ChemMedChem
theoretical aspects and recent applications. Curr Chem Genomics.
2009 May 28;3:22-32
[a] UCB Pharma, UCB NewMedicines ; Chemin du Foriest, 1420,
Braine-L’Alleud (Belgium)
[a*] UCB Pharma, UCB NewMedicines ; Chemin du Foriest, 1420,
Braine-L’Alleud (Belgium), ali.ates@ucb.com
7
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10.1002/cmdc.201800026
ChemMedChem
Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATIONS
H
Ali Ates, Burssens Pierre, Lorthioir
Olivier, Lo Brutto Patrick, Dehon
Gwenael, Keyaerts Jean, Coloretti
In the present study, a novel
Non-selective HTS hit
N
chemical series of serotonin 5-
HT7 antagonist is described. The
H
O
N
5-HT7 pKi: 7.1
Francis,
Bénédicte
Lallemand,
MW: 342.5
HTS hit
synthesis,
relationships
structure-activity
and selectivity
Valérie Verbois, Michel Gillard and
Céline Vermeiren
OMe
profile are reported. This series
includes 5-HT7 antagonists with
unprecedented good selectivity
for 5-HT7 receptor.
Page No. – Page No.
Novel 5-HT7 antagonists, with an
unprecedented selectivity profile
O
N
High 5-HT7 affinity
and selectivity
N
R2
R1
8
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