Design and synthesis of fused tetrahydroisoquinoline-iminoimidazolines

Article abstract of DOI:10.1016/j.ejmech.2015.10.030

In the aim of identifying new privileged structures, we describe the 5-steps synthesis of cyclic guanidine compounds "tetrahydroisoquinoline-iminoimidazolinesg" derived from tetrahydroisoquinoline-hydantoin core. In order to evaluate this new minimal structure and the impact of replacing a carbonyle by a guanidine moiety, their affinity towards adenosine receptor A_2A was evaluated and compared to those of tetrahydroisoquinoline-hydantoin compounds.

Full text of DOI:10.1016/j.ejmech.2015.10.030

European Journal of Medicinal Chemistry 106 (2015) 15e25
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Research paper
Design and synthesis of fused tetrahydroisoquinoline-
iminoimidazolines
a
,
,
Valeria Moas-Heloire b, Nicolas Renault a b, Vania Batalha c, Angela Rincon Arias e,
ꢀ
Mathieu Marchivie d, Said Yous a , Noemie Deguine , Luc Buee e, Philippe Chavatte a
,
,
e
a
a,
, f
ꢀ
ꢀ
David Blum a e, Luisa Lopes c, Patricia Melnyk a **, Laurence Agouridas a
,
,
e
,
, e, *
a
ꢀ
Universite de Lille, F-59000 Lille, France
b UDSL, EA 4481, UFR Pharmacie, F-59000 Lille, France
c Instituto de Medecina Molecular, 1640-028, Lisbon, Portugal
d
ꢀ
Universite Bordeaux, CNRS FRE3396, F-33000 Bordeaux, France
e Inserm UMR-S1172, JPArc, F-59000 Lille, France
f Inserm UMR 995, LIRIC, F-59000 Lille, France
a r t i c l e i n f o
a b s t r a c t
Article history:
In the aim of identifying new privileged structures, we describe the 5-steps synthesis of cyclic guanidine
compounds “tetrahydroisoquinoline-iminoimidazolines” derived from tetrahydroisoquinoline-hydantoin
core. In order to evaluate this new minimal structure and the impact of replacing a carbonyle by a
guanidine moiety, their affinity towards adenosine receptor A2A was evaluated and compared to those of
tetrahydroisoquinoline-hydantoin compounds.
Received 1 July 2015
Received in revised form
14 October 2015
Accepted 15 October 2015
Available online 19 October 2015
© 2015 Elsevier Masson SAS. All rights reserved.
Keywords:
Guanidines
A2A receptor
Privileged structure
Iminoimidazoline
1. Introduction
various targets [1e3]. In fact, these minimal structures constitute a
powerful starting point to identify original compounds by varying
In the field of medicinal chemistry, privileged structures are
considered as a promising source of ligands able to interact with
the nature of their substituents. They constitute an anchor point
enabling to orientate substituents in various positions, giving ac-
cess to potentially promising structures and to modulate their af-
finity and activity. Therefore, identification of novel privileged
structures appears as an interesting challenge.
Abbreviations: Tic-H, tetrahydroisoquinoline-hydantoin; A2AR, adenosine A2A
receptor.
* Corresponding author. “Onco and NeuroChemistry”, Jean-Pierre Aubert
Our group described
a series of tetrahydroisoquinoline-
hydantoins (Tic-H 1, Fig. 1) derived compounds with potent affin-
ity for the sigma-1 receptor in the nanomolar range ensuing various
therapeutical in vivo applications [4e9]. This heterocycle presents
an interesting hydrogen bond acceptor group on the hydantoin
cycle and is amenable to various decorations. In this study we
proposed to identify a new potential privileged structure and
decided to evaluate the consequence of replacing the hydantoin's
(1) hydrogen bond acceptor by a hydrogen bond donor group
resulting in the guanidine moiety of compound 2 (Fig. 1). This new
heterocycle could be the central core for the design of new active
compounds. Guanidines are present in a large variety of natural
products with potent biological activities in many fields [10e13]
ꢀ
Research Center, UMR-S1172, Faculte des Sciences Pharmaceutiques et Biologiques
ꢀ
(Universite Lille 2), UFR Pharmacie, 3, rue du Pr Laguesse, BP83, 59006 Lille Cedex,
France.
** Corresponding author. “Onco and NeuroChemistry”, Jean-Pierre Aubert
ꢀ
Research Center, UMR-S1172, Faculte des Sciences Pharmaceutiques et Biologiques
ꢀ
(Universite Lille 2), UFR Pharmacie, 3, rue du Pr Laguesse, BP83, 59006 Lille Cedex,
France.
ꢀ
E-mail addresses: valeria.heloire-2@univ-lille2.fr (V. Moas-Heloire), nicolas.
renault-3@univ-lille2.fr (N. Renault), vanialnbatalha@gmail.com (V. Batalha),
ararias@quim.ucm.es
(A.R.
Arias),
mathieu.marchivie@icmcb.cnrs.fr
ꢀ
(M. Marchivie), said.yous@univ-lille2.fr (S. Yous), luc.buee@inserm.fr (L. Buee),
philippe.chavatte@univ-lille2.fr (P. Chavatte), david.blum@inserm.fr (D. Blum),
lvlopes@medicina.ulisboa.pt (L. Lopes), patricia.melnyk@univ-lille2.fr (P. Melnyk),
laurence.agouridas@univ-lille2.fr (L. Agouridas).
http://dx.doi.org/10.1016/j.ejmech.2015.10.030
0223-5234/© 2015 Elsevier Masson SAS. All rights reserved.

ꢀ
16
V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
2.2. Chemical synthesis
Synthesis of Tic-guanidine derivatives of series A and B was
achieved thanks to a unique chemical pathway as depicted in
Scheme 1. This enabled us to access desired compounds starting
from commercially available amino acids and therefore to easily
access various pharmacomodulations. We optimized the syn-
Tic-hydantoin 1
thetic pathway of compound
2 starting from commercially
available Boc-protected -tetrahydroisoquinoline carboxylic acid I
L
whose chemistry is well mastered in our group [7,9,33]. Key step
of this synthesis was the final formation of the cyclic guanidine.
Various methods are described in the literature to access gua-
nidines [12] and cyclic guanidines [34e36] but could not be
applied to our strategy. Indeed, we previously described the
synthesis of Tic-thiohydantoins, which could be an interesting
intermediate for the synthesis of these Tic-guanidines. However
their chemical and enantiomeric instability precluded their use
in this study [37]. For final formation of guanidine cycle, direct
cyclization of the free diamine in the presence of cyanogen
bromide [38e44] was unsuccessful. Some adjustments were then
required and we finally chose to maintain Boc-protection in order
to selectively functionalize the free amine of compounds 2be13b
with cyanogene bromide [45]. Expected guanidines were ob-
tained after Boc-deprotection and subsequent cyclization of
intermediate.
Tic-guanidine 2
series A
series B
Fig. 1. Tic-guanidine derivatives of series A and B.
and more specifically in the central nervous system area [14,15].
This approach was exemplified by preparing the guanidine de-
rivative “Tic-guanidine” and its derivatives (2e13) in order to
evaluate the affinity of this new series on the adenosine receptor
A
2AR [16]. In fact, in addition to its affinity towards sigma-1 re-
ceptor, Tic-H 1 showed a promising affinity constant towards
M). This receptor is widely
adenosine receptor A2A (Ki ¼ 44
m
expressed in the central nervous system. Expressed at different
levels (neurons, astrocytes, microglial cells) [17e21], it acts at
various levels of regulation [22e25]. Therefore, A2ARs are viewed as
promising targets in various neurodegenerative diseases, mainly
Parkinson's and Alzheimer's diseases [26e28].
Synthesis of series A started from Boc-protected L-tetrahy-
droisoquinoline carboxylic acid I. Corresponding aldehyde was
obtained via reduction of Weinreb amide II [46,47] using LiAlH4 in
THF at 0 ꢀC [46]. Reductive amination with appropriate amine in the
presence of sodium triacetoxyborohydride in CH2Cl2 gave expected
Boc-monoprotected derivatives 2be6b [48]. Free amine of this last
compound was then functionalized by cyanogen bromide in
ethanol to give corresponding nitrile derivatives [45]. Finally, gua-
nidine cyclization was achieved thanks to acidic deprotection of the
carbamate and in situ cyclization of the intermediate diamine
compound with yields from 46 to 88%.
Docking studies, based on the crystal structure of A2A bound to
the high affinity antagonist (ZM241385) [29], showed that Tic-
guanidine restored hydrogen bonds that were missing for Tic-H
leading us to expect a better affinity of these compounds [30].
We therefore aim to develop a new series of Tic-guanidine
compound. We set up an original and efficient chemical synthesis
allowing pharmacomodulations that concern the nature of the
substituents on the original tricyclic structure Tic-guanidine (series
A, Fig. 1) but also modifications by the central cyclic core's opening
(series B, Fig. 1).
Depending on the nature of the amine in the reductive
amination step, compounds 2 to 6 were first obtained (Scheme
1), as depicted in Fig. 3. On the other hand, opening of the up-
per part of the central cycle while maintaining N-benzyl sub-
stitution of the guanidine (Scheme 2) core resulted from
modification of starting amino acid (compounds 7e13, Fig. 4).
Compound 12, derived from tyrosine, was prepared from Boc-
Tyr(tBu)-OH. The tert-butyl protection was removed in the final
cyclization step.
2. Results and discussion
2.1. Modeling studies
Jaakola et al. published in 2008 a crystal structure of A2AR with
the high affinity antagonist ZM241385 [29]. Tic-H and Tic-
guanidine were both docked in
A2AR's binding site. Results
showed both molecules place in a same manner as ZM241385 does
(Fig. 2). Mainly, important hydrogen bonds with Glu169 and Asn253
missing in the case of Tic-H are being restored with the guanidine
function. Finally, upper carbonyl moiety of Tic-H was not main-
tained, as it doesn't seem to play an essential role in the interactions
with amino acids of the binding site.
Supported by our docking studies, pharmacomodulations are
presented: various N-substituents on the guanidine core (series A,
Fig.1) and the central tricyclic core's opening (series B, Fig.1). Series
A enables us to evaluate the effect of the modification of the benzyl
group in the hydrophobic upper pocket of the binding site. On the
other hand, series B was prepared in order to evaluate the impor-
tance of the central core's nature and especially how its geometry
impacts compounds' affinity. We wanted to establish whether a
planar conformation was essential as described for many A2A's
antagonists [16,28,31] or if less restricted structures could improve
affinity as compared to already published non planar A2A antago-
nists [16,28,31,32]. Finally, B series would bring additional in-
formations on structure activity relationships of our Tic-guanidine
compounds.
Structure of final compounds was confirmed by various analysis
methods. LCeMS gave expected mass, discarding the formation of
the dimer. FT-IR indicated the disappearance of the nitrile band
(2260e2240 cmꢁ1) and appearance of the guanidine C]NH bond
(1690e1640 cmꢁ1) confirming cyclization of the compound (see
Supporting information). Finally, 1D and 2D 1H and 13C NMR
showed appropriate signals and correlations, especially the gua-
nidine C]NH bond.
Some of our compounds were able to crystallize. X-ray
spectroscopy thus enabled us to confirm not only the structure
and enantiopurity of compounds 2 and 3 (Fig. 5) but also com-
pounds 7, 9 and 11 whose absolute configuration was maintained
(Fig. 6) [49].
On the other hand, crystallographic data showed compound 8
was present as a racemic mixture (for details, see Supporting
information). This compound differs from the other ones, as it is
N-methylated. N-methylation was achieved following a protocol
described in the literature to be a non-epimerizing route [50].
However, in our case, the basic conditions of methylation afforded
complete racemization (Fig. 6).

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
17
Fig. 2. A2AR's crystal structure with (i) high-affinity antagonist ZM241385, (ii) Tic-H 1 and (iii) Tic-guanidine 2. Hydrogen bonds with Glu169 and Asn253 missing with Tic-H (ii) are
being restored with the guanidine function (iii).
i
ii,iii
I
II
2b-6b
iv
v
2-6
Scheme 1. i) HNMe(OMe)$HCl, EDC, HOBt, NMM, CH3CN, CH2Cl2, 61%; ii) LiAlH4, THF 0 ꢀC then aq. KHSO4, 66%; iii) R-NH2, NaHB(OAc)3, CH2Cl2 then aq. NaHCO3, 92%-quant; iv)
BrCN, NaHCO3, EtOH, 54e97%; v) HCl, dioxane, 46e88%.
2
3
4
5
6
Fig. 3. Pharmacomodulations of compounds 2e6 of the Tic-guanidine core using various amines in the reductive amination step.

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
18
i
ii, iii
7b-13b
7-13
7a-13a
v
iv
Scheme 2. i) HNMe(OMe)$HCl, EDC, HOBt, NMM, CH3CN, CH2Cl2, 36e86%; ii) LiAlH4, THF 0 ꢀC then aq. KHSO4, 20e97%; iii) Bn-NH2, NaHB(OAc)3, CH2Cl2 then aq. NaHCO3, 19e99%;
iv) BrCN, NaHCO3, EtOH, 44e94%; v) HCl, dioxane, 23e90%.
7
8
9
12 R = H
13 R = Me
10
11
Fig. 4. Opening of the central Tic-guanidine core.
Fig. 5. Thermal ellipsoid drawing [49] (30% probability) of the asymmetric unit of compound 2 (left) and 3 (right) showing the molecular structure and the labeling scheme.

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
19
Fig. 6. Thermal ellipsoid drawing [49] (30% probability) of the asymmetric unit of compound 7e9 and 11 showing the molecular structure and the labeling scheme.
2.3. Affinity of Tic-guanidine compounds
necessary to bind the A2AR receptor as open structures (7e13)
showed no affinity at all. X-ray analysis helped understanding this
observation. In fact, as shown in Fig. 5, open Tic-guanidine from
series B adopt a curved conformation that does not allow the
binding of the molecule in the pocket of the receptor whereas tri-
cyclic structures keep a flat conformation [51]. On the other hand,
compared to already published non-planar structures [16,28,31,32],
our open Tic-guanidines compounds are not aromatic and this
could explain the lack of efficacy as regards to the affinity.
Concerning the tricyclic structures (2e6), we therefore assume
the replacement of carbonyle moiety of 1 by a hydrogen bond
donor does not give us expected improved affinity for the A2AR.
More generally, low affinities of our Tic-guanidine compounds
of both series might be improved by adding functionalized chains
likely to favor interactions in the binding site.
Affinity of our compounds was evaluated on human A2A re-
ceptor membranes stably expressed in HEK293 cells. Results
(Table 1) showed no improvement of binding compared to initial
Tic-H compound 1 (Ki ¼ 44
substituted with phenylbutylamine 5 (Ki ¼ 35
ically, affinity was drastically decreased for open guanidines.
Except compound 5 (35 M) that gives an affinity comparable to
the one of Tic-H 1 (44 M), binding was not improved with our Tic-
mM) except for the tricyclic guanidine
mM). More specif-
m
m
guanidine compounds. For sure, rigid tricyclic structures are
Table 1
A2A receptor affinity (Ki) and cytotoxicity assays of compounds 1e13.
2.4. Cytotoxicity of Tic-guanidine compounds
Cpd
Ki (
m
M)a
CC50 (m
M)b
Cytotoxicity assays have been conducted on SY5Y cells and
showed no toxicity of our compounds at 100 mM.
1
2
3
4
5
6
7
8
44
64
>200
>200
35
>200
>200
>200
>200
>200
>200
>200
>200
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
3. Conclusion
As Tic-H core was a structure of interest for the design of various
biologically active compounds, we proposed the Tic-guanidine core
as a new privileged structure. This work therefore presented a new
and efficient synthesis of guanidine cycles derived from amino
acids. We applied this concept to the design of A2AR ligands. Un-
fortunately, binding results established that our initial hypothesis
was not confirmed: replacement of the hydrogen bond acceptor
moiety carbonyl of compound 1 by the hydrogen bond donor
guanidine did not improve the affinity for A2AR. Other decorations
are needed to improve the affinity for A2AR. The lack of cytotoxicity
9
10
11
12
13
a
A2AR's agonist CGS-21680 used as a reference (Ki ¼ 0.503
mM). Displacement of
specific [3H]-ZM 241385 binding in membranes obtained from hA2a receptor stably
expressed in HEK293 cells.
b
Cytotoxicity assays on SY5Y cells.

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
20
of this new scaffold constitutes a major advantage. Thus valoriza-
tion of this new scaffold for other receptors is currently under
evaluation.
3.7 mL/mmol of carboxylic acid), EDC (1.3 eq.), HOBt (1.3 eq.), NMM
(6.5 eq.) and HN(Me)OMe.HCl (2.1 eq.) were added. The mixture
was stirred at room temperature over 24e72 h and then evapo-
rated. The resulting crude product was dissolved in CH2Cl2, washed
three times with saturated NaHCO3 solution, three times with 1 M
HCl and once with brine. Organic layer was dried over MgSO4,
filtered and concentrated in vacuo. Purification via flash chroma-
tography was performed.
4. Experimental section
4.1. General information
Chemicals and solvents were obtained from commercial sour-
ces, and used without further purification unless otherwise noted.
Reactions were monitored by TLC performed on MachereyeNagel
Alugram® Sil 60/UV254 sheets (thickness 0.2 mm). Purification of
products was carried out by either column chromatography or thick
layer chromatography. Column chromatography was carried out
using MachereyeNagel silica gel (230e400 mesh). Thick layer
chromatography was performed on glass plates coated with
MachereyeNagel Sil/UV254 (thickness 2 mm), from which the pure
compounds were extracted with the following solvent system:
DCM/MeOH (NH3), 90:10. NMR spectra were recorded on a Bruker
DRX 300 spectrometer (operating at 300 MHz for 1H and 75 MHz
for 13C). Chemical shifts are expressed in ppm relative to either
tetramethylsilane (TMS) or to residual proton signal in deuterated
4.2.2. tert-Butyl (3S)-3-[methoxy(methyl)carbamoyl]-3,4-dihydro-
1H-isoquinoline-2-carboxylate (II)
According to general method 1, II was obtained as a colorless oil
(5.13 g, 61%). 1H NMR (CDCl3, 300 MHz),
d (ppm) indicates the
presence of 2 conformers: 7.15e7.20 (m, 4H); 5.23 and 4.86 [X part of
ABX system (ft, J ¼ 6.0 Hz, 0.5H) and (ft, J ¼ 7.5 Hz, 0.5H)]; 4.70 and
4.69 [(AB system, J ¼ 16.5 Hz, 1H, Dn ¼ 36 Hz) and (AB system,
J ¼ 16.5 Hz, 1H, Dn ¼ 123 Hz)]; 3.85 and 3.78 (2s, 3H); 3.19 and 3.16
(2s, 3H); 3.19e2.94 (unresolved AB part of ABX system, m, 2H); 1.51
and 1.45 (2s, 9H). 13C NMR (CDCl3, 75 MHz),
d (ppm) indicates the
presence of 2 conformers: 175.6, 174.9, 173.0, 155.3, 154.9, 154.7,
135.5, 134.7, 134.2, 133.9, 133.0, 132.9, 132.9, 132.7, 132.1, 129.9,
129.4, 128.8, 127.9, 127.7, 127.6, 127.1, 125.8, 83.9, 81.6, 80.4, 61.7,
61.5, 61.3, 54.8, 53.5, 53.2, 52.3, 50.745.4, 44.5, 43.4, 32.7, 32.5, 32.2,
30.9, 30.4, 30.1, 29.8, 28.4, 28.3, 28.1. MS (ESIþ): m/z ¼ 321.1 [M,H]þ
found; C17H25N2O4 calculated m/z ¼ 321.2 [M,H]þ.
solvents. Chemical shifts are reported as position (d in ppm), mul-
tiplicity (s ¼ singlet, d ¼ doublet, t ¼ triplet, q ¼ quartet, p ¼ pentet,
dd ¼ double doublet, br ¼ broad and m ¼ multiplet), coupling
constant (J in Hz), relative integral and assignment. The attributions
of protons and carbons were achieved by analysis of 2D experi-
ments (COSY, HSQC and HMBC). Mass spectra were recorded on a
Varian triple quadrupole 1200W mass spectrometer equipped with
a non-polar C18 TSK-gel Super ODS (4.6 ꢂ 50 mm) column, using
electrospray ionization and a UV detector (diode array). HRMS-ESI
spectra were recorded on a Thermo Scientific Exactive spectrom-
eter. The purity of final compounds was verified by two types of
high pressure liquid chromatography (HPLC) columns: C18 Inter-
chrom UPTISPHERE and C4 Interchrom UPTISPHERE. Analytical
HPLC was performed on a Shimadzu LC-2010AHT system equipped
with a UV detector set at 254 nm and 215 nm. Compounds were
4.2.3. tert-Butyl N-[(1S)-1-benzyl-2-[methoxy(methyl)amino]-2-
oxo-ethyl]carbamate (7a)
According to general method 1, 7a was obtained as a brown oil
(0.94 g, 66%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.29e7.12 (m,
5H); 5.18 and 5.03e4.86 [X part of ABX system (d, J ¼ 6.0 Hz, 0.5H)
and (m, 0.5H)]; 3.65 (s, 3H); 3.16 (s, 3H); 2.95 [AB part of ABX
system (dd, J ¼ 12.0 and 6.0 Hz,1H) and (dd, J ¼ 15.0 and 9.0 Hz,1H),
Dn ¼ 60 Hz]; 1.39 (s, 9H) [52].
4.2.4. tert-Butyl N-[(1S)-1-benzyl-2-[methoxy(methyl)amino]-2-
oxo-ethyl]-N-methyl-carbamate (8a)
dissolved in 50
m
L methanol and 950
m
L buffer A, and injected into
According to general method 1, 8a was obtained as a yellow oil
the system. The following eluent systems were used: buffer A (H2O/
TFA, 100:0.1) and buffer B (CH3CN/H2O/TFA, 80:20:0.1). HPLC
retention times (HPLC tR) were obtained at a flow rate of 0.2 mL/
min for 35 min using the following conditions: a gradient run from
100% of buffer A over 1 min, then to 100% of buffer B over the next
30 min. The melting point analyses were performed on Barnstead
Electrothermal Melting Point Series IA9200 and are uncorrected.
Infrared spectra were performed on Bruker FT-IR spectrometer
(0.942 g, 86%). 1H NMR (CDCl3, 300 MHz),
d (ppm): indicates the
presence of 2 conformers. 7.27e7.16 (m, 5H); 5.64e5.07 [unresolved
X part of ABX system, m, 1H); 3.64 and 3.61 (2s, 3H); 3.16 and 3.19
(2s, 3H); 3.06e2.87 [unresolved AB part of ABX system, m, 2H]; 2.85
(s, 3H); 1.35 and 1.23 (2s, 9H). 13C NMR (CDCl3, 75 MHz),
d (ppm):
indicates the presence of 2 conformers. 171.5, 155.6, 154.9, 138.0,
137.5, 129.4, 129.2, 128.4, 128.2, 126.4, 79.8, 61.3, 57.2, 54.7, 34.9,
30.2, 29.8, 28.2, 26.8. MS (ESIþ): m/z ¼ 323.0 [M,H]þ found;
model
a
. Preparative HPLC were performed using a Varian PRoStar
C
17H26N2O4 calculated m/z ¼ 323.2 [M,H]þ.
system using an OmniSphere 10 column C18 250 mm ꢂ 41.4 mm
Dynamax from Varian, Inc. A gradient starting from 20% CH3CN/80%
H2O/0.1% formic acid and reaching 100% CH3CN/0.1% formic acid at
a flow rate of 80 mL/min was used. Optical rotations were measured
at 20 ꢀC on a PerkineElmer 343 polarimeter.
4.2.5. tert-Butyl N-[(1S)-1-[(4-fluorophenyl)methyl]-2-
[methoxy(methyl)amino]-2-oxo-ethyl]carbamate (9a)
According to general method 1, 9a was obtained as a colorless oil
(0.810 g, 70%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.18e7.09 (m,
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication
1401476, 1401477, 1401478, 1401480, 1401481 and 1401479. Copies
of the data can be obtained, free of charge, on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax: þ44-(0)1223-336033
or email: deposit@ccdc.cam.ac.uk).
2H); 7.02e6.90 (m, 2H); 5.28e5.17 (d, J ¼ 12.1 Hz, 1H), 5.00e4.82
(unresolved X part of ABX system, m, 1H); 3.67 (s, 3H); 3.16 (s, 3H);
2.87 [AB part of ABX system (dd, J ¼ 12.2 and 6.3 Hz, 1H) and (dd,
J ¼ 12.1 and 6.6 Hz, 1H), Dn ¼ 60 Hz]; 1.38 (s, 9H). 13C NMR (CDCl3,
75 MHz),
d
(ppm): 172.0, 163.5, 160.2 (JCeF ¼ 234 Hz); 155.1, 132.3,
131.0, 130.9, 115.3, 115.0, 79.6, 61.6, 51.5, 38.1, 32.0, 28.3. MS (ESIþ):
m/z ¼ 327.1 [M,H]þ found; C16H24FN2O4 calculated m/z ¼ 327.2
[M,H]þ.
4.2. Preparation of Weinreb amide compounds
4.2.6. tert-Butyl (2S)-2-[methoxy(methyl)carbamoyl]piperidine-1-
carboxylate (10a)
4.2.1. General method 1
To a solution of appropriate amino protected carboxylic acid
derivative (1 eq.) dissolved in a mixture of CH2Cl2 and CH3CN (1:1,
According to general method 1, 10a was obtained as a yellow oil
(0.986 g, 83%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 5.18e4.87 (m,

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
21
1H); 4.10e3.84 (m,1H); 3.76 (s, 3H); 3.58e3.39 (m,1H); 3.18 (s, 3H);
2.01 (d, J ¼ 15.0 Hz, 1H); 1.75e1.57 (m, 3H); 1.44 (s, 9H); 1.34e1.20
4.3.4. tert-Butyl (3S)-3-[(2-morpholinoethylamino)methyl]-3,4-
dihydro-1H-isoquinoline-2-carboxylate(4b)
(m, 2H). 13C NMR (CDCl3, 75 MHz),
d
(ppm): 173.5, 156.2, 79.7, 61.3,
According to general method 2, 4b was obtained as a colorless
50.8, 42.3, 32.2, 29.7, 28.5, 26.5, 19.6. MS (ESIþ): m/z ¼ 273.1 [M,H]þ
oil (0.428 g, 99%). 1H NMR (CDCl3, 300 MHz),
d
(ppm): 7.22e7.08 (m,
found; C13H25N2O4 calculated m/z ¼ 273.2 [M,H]þ.
4H); 4.83e4.49 (unresolved AB system, m, 2H); 4.25 [X part of ABX
system (d, J ¼ 18.0 Hz, 1H, CH(b))]; 3.70 (ft, J ¼ 3.0 Hz, 4H); 2.92 [AB
part of ABX system (dd, J ¼ 16.4 and 6.7 Hz, 1H) and (d, J ¼ 12.0 Hz,
1H), Dn ¼ 96 Hz]; 2.75e2.68 (m, 2H); 2.44e2.42 (m, 8H); 1.51 (s,
4.2.7. tert-Butyl N-[(1S)-2-(methoxy(methyl)amino)-1-methyl-2-
oxo-ethyl]carbamate (11a)
According to general method 1, 11a was obtained as a yellow oil
(0.566 g, 64%). Analyses similar to literature description [53].
9H). 13C NMR (CDCl3, 75 MHz),
d (ppm): 155.3, 133.1, 129.1, 126.6,
126.2, 79.9, 67.0, 58.3, 53.7, 53.4, 50.8, 45.9, 42.7, 31.1, 28.5. MS
(ESIþ): m/z ¼ 376.1 [M,H]þ found; C21H34N3O3 calculated m/
z ¼ 376.2 [M,H]þ.
4.2.8. tert-Butyl N-[(1S)-1-[(4-tert-butoxyphenyl)methyl]-2-
[methoxy(methyl)amino]-2-oxo-ethyl]carbamate (12a)
According to general method 1, 12a was obtained as a yellow
solid (0.722 g, 76%). Analyses similar to literature description [54].
4.3.5. tert-Butyl (3S)-3-[(4-phenylbutylamino)methyl]-3,4-
dihydro-1H-isoquinoline-2-carboxylate (5b)
According to general method 2, 5b was obtained as a colorless
4.2.9. tert-Butyl N-[(1S)-2-[methoxy(methyl)amino]-1-methyl-2-
oxo-ethyl]carbamate (13a)
According to general method 1, 13a was obtained as a yellow
solid (0.225 g, 48%). Analyses similar to literature description [55].
oil (0.416 g, 92%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 8.19 (br s,
1H); 7.30e7.10 (m, 9H); 4.65 (m, 2H); 4.30 [X part of ABX system (d,
J ¼ 15.0 Hz,1H)]; 3.12e2.59 (m, 8H); 1.70e1.52 (m, 4H); 1.49 (s, 9H).
13C NMR (CDCl3, 75 MHz),
d (ppm): 156.0, 154.9, 141.8, 132.8, 132.4,
128.9, 128.3, 127.0, 126.6, 126.1, 125.8, 80.8, 50.4, 49.3, 48.1, 47.8,
43.9, 42.7, 35.4, 31.7, 28.4, 27.6, 27.0, 22.7. MS (ESIþ): m/z ¼ 395.2
[M,H]þ found; C25H35N2O2 calculated m/z ¼ 395.3 [M,H]þ.
4.3. Preparation of amine compounds 2be13b
4.3.1. General method 2
To a solution of Weinreb amide (1 eq.) in THF was added LiAlH4
(0.9 eq. of commercial solution 1 M in THF) dropwise under N2 at
0 ꢀC and stirred for 1 h at 0 ꢀC. Then saturated KHSO4 solution was
added dropwise. THF was evaporated off. The resulting crude
product was dissolved in CH2Cl2, washed twice with saturated
NaHCO3 solution, twice with 1 M HCl, once with brine. Organic
layer was dried over MgSO4, filtered and concentrated in vacuo. No
further purification was performed. To a solution of resulting
aldehyde (1 eq.) in CH2Cl2, benzylamine (1.2 eq.) was added under
N2. The mixture was stirred at room temperature for 30 min,
NaBH(OAc)3 (3 eq.) was added portion wise (at least for 10 min).
The mixture was stirred overnight, diluted with CH2Cl2 (3 mL) and
saturated NaHCO3 solution (3 mL) was added. The mixture was
stirred for 10 min. The organic layer was separated and the aqueous
phase washed twice with CH2Cl2 (15 mL). Combined organic layers
were dried over MgSO4, filtered and evaporated in vacuo. Purifi-
cation via flash chromatography was performed.
4.3.6. tert-Butyl (3S)-3-[(hexylamino)methyl]-3,4-dihydro-1H-
isoquinoline-2-carboxylate (6b)
According to general method 2, 6b was obtained as a colorless
oil (0.386 g, 97%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.23e7.10 (m,
4H); 4.88e4.13 (m, 2H); 4.37e4.15 (m, 1H); 3.09 (AB part of ABX
system, dd, J ¼ 16.2 Hz and 6.9 Hz, 1H); 2.85e2.67 (m, 5H); 2.04 (s,
3H); 1.50 (s, 9H); 1.33e1.23 (m, 6H); 0.87 (t, J ¼ 7.5 Hz, 3H). 13C NMR
(CDCl3, 75 MHz),
d (ppm): 170.0, 133.0, 132.7, 128.9, 126.9, 126.4,
126.0, 80.5, 50.9, 50.4, 48.3, 39.7, 31.5, 29.6, 28.7, 28.2, 28.0, 22.5,
13.9. MS (ESIþ): m/z ¼ 347.2 [M,H]þ found; C21H35N2O2 calculated
m/z ¼ 347.3 [M,H]þ.
4.3.7. tert-Butyl N-[(1S)-1-benzyl-2-(benzylamino)ethyl]carbamate
(7b)
According to general method 2, 7b was obtained as a brown
solid (0.498 g, 90%). Analyses similar to literature description [56].
4.3.8. tert-Butyl N-[(1S)-1-benzyl-2-(benzylamino)ethyl]-N-
methyl-carbamate (8b)
4.3.2. tert-Butyl (3S)-3-[(benzylamino)methyl]-3,4-dihydro-1H-
isoquinoline-2-carboxylate (2b)
According to general method 2, 8b was obtained as a light yel-
According to general method 2, 2b was obtained as a colorless
low oil (0.120 g, 52%). 1H NMR (CDCl3, 300 MHz),
d (ppm): indicates
oil (0.55 g, 95%). 1H NMR (CDCl3, 300 MHz),
d
(ppm): 7.36e7.21 (m,
the presence of 2 conformers. 7.44e7.05 (m, 10H); 4.71e4.34 (un-
resolved X part of ABX system, m, 1H); 3.89 and 3.71 [AB part of
ABX system (d, J ¼ 13.1 Hz, 1H) and (m, 1H)]; 2.93e2.55 (m, 7H);
2.00 (br s, 1H); 1.38 and 1.28 (2s, 9H). 13C NMR (CDCl3, 75 MHz),
5H); 7.20e7.03 (m, 4H); 5.53 (s, 1H); 4.92e4.45 (m, 2H); 4.22 and
4.17 (2s, 1H); 3.85 (dd, J ¼ 19.5 Hz and 13.4 Hz, 2H); 2.93 [AB part of
ABX system (dd, J ¼ 18.0 and 6.0 Hz, 1H) and (dd, J ¼ 15.0 and
3.0 Hz, 1H), Dn ¼ 90 Hz]; 2.72e2.58 (unresolved AB part of ABX
d
(ppm): 156.3, 138.6, 129.0, 128.4, 128.2, 127.1, 126.6, 79.6, 55.6,
system, m, 2H); 1.49 (s, 9H). 13C NMR (CDCl3, 75 MHz),
d
(ppm):
53.2, 50.1, 49.6, 36.9, 28.2. MS (ESIþ): m/z ¼ 355.1 [M,H]þ found;
155.4, 140.5, 132.9, 129.1, 128.4, 128.0, 126.9, 126.6, 126.1, 79.9, 53.5,
50.1, 50.1, 48.3, 43.1, 31.1, 28.5. MS (ESIþ): m/z ¼ 353.3 [M,H]þ
found; C22H29N2O2 calculated m/z ¼ 353.2 [M,H]þ.
C
22H30N2O2 calculated m/z ¼ 355.2 [M,H]þ.
4.3.9. tert-Butyl N-[(1S)-1-[(benzylamino)methyl]-2-(4-
fluorophenyl)ethyl]carbamate (9b)
4.3.3. tert-Butyl (3S)-3-[[2-(2-pyridyl)ethylamino]methyl]-3,4-
dihydro-1H-isoquinoline-2-carboxylate (3b)
According to general method 2, 9b was obtained as a light yel-
low oil (0.510 g, 70%). 1H NMR (CDCl3, 300 MHz),
d (ppm):
According to general method 2, 3b was obtained as a light
7.38e7.22 (m, 5H); 7.16e7.08 (m, 2H); 7.01e6.89 (m, 2H); 4.74 (br s,
1H), 3.99e3.85 (unresolved X part of ABX system, m, 1H); 3.77 (AB
system, J ¼ 12.4 Hz, Dn ¼ 24 Hz, 2H); 2.90e2.71 (unresolved AB part
of ABX system, m, 2H); 2.71e2.54 (unresolved AB part of ABX
system, m, 2H); 2.10 (br s, 1H); 1.41 (s, 9H). 13C NMR (CDCl3,
brown oil (0.386 g, quantitative). 1H NMR (CDCl3, 300 MHz),
d
(ppm): 8.53 (s, 1H); 7.69e6.78 (m, 8H); 5.01e4.63 (unresolved AB
system, m, 2H); 4.39e4.13 (m, 1H); 3.32e2.64 (m, 8H); 1.45 (s, 9H).
13C NMR (CDCl3, 75 MHz),
(ppm): 159.4, 136.8, 132.6, 132.0, 129.1,
d
126.7,126.38, 123.5,121.6, 80.5, 49.3, 48.6, 47.8, 31.4, 29.0, 28.6, 28.1,
27.7. MS (ESIþ): m/z ¼ 368.2 [M,H]þ found; C22H30N3O2 calculated
m/z ¼ 368.2 [M,H]þ.
75 MHz),
d
(ppm): 163.2, 160.0 (JCeF ¼ 242.2 Hz); 155.6,139.9,133.8,
130.8, 130.7, 128.5, 128.2, 127.1, 115.3, 115.0, 79.4, 53.7, 51.4, 51.2,
38.3, 28.4. MS (ESIþ): m/z ¼ 359.0 [M,H]þ found; C21H28FN2O2

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
22
calculated m/z ¼ 359.2 [M,H]þ.
4H); 4.72e4.54 (m, 4H); 4.11e4.01 (m, 1H); 3.61 [AB part of ABX
system (t, J ¼ 9.0 Hz, 1H) and (t, J ¼ 6.0 Hz, 1H), Dn ¼ 144 Hz]; 2.95
4.3.10. tert-Butyl (2S)-2-[(benzylamino)methyl]piperidine-1-
carboxylate (10b)
[AB part of ABX system (dd, J ¼ 18.0 and 9.0 Hz,1H) and (dd, J ¼ 15.0
and 9.0 Hz, 1H), Dn ¼ 72 Hz]. 13C NMR (CD3OD, 75 MHz),
d (ppm):
According to general method 2, 10b was obtained as a yellow oil
156.7,134.4,132.0,129.9,129.1,128.8,128.1,127.7,127.0,126.8,126.2,
53.2, 51.7, 48.5, 43.9, 33.4. HRMS (ESIþ): m/z ¼ 278.16548 [M,H]þ
found; C18H19N3 calculated m/z ¼ 278.16517 [M,H]þ. Mp: 198.5 ꢀC.
(0.453 g, 62%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.37e7.20 (m,
5H); 4.45e4.32 (unresolved X part of ABX system, m, 1H);
4.02e3.87 (m, 1H); 3.83 (AB system, d, J ¼ 12.0 Hz, Dn ¼ 24.2 Hz,
1H); 2.79 [AB part of ABX system (dd, J ¼ 12.3 and 3.1 Hz, 1H) and
(dd, J ¼ 12.0 and 6.6 Hz, 1H), Dn ¼ 81.2 Hz); 2.73e2.69 (m, 1H);
aD (20 ꢀC, CH3OH) ¼ ꢁ0.548ꢀ (0.500 mg/mL). IR,
n
(cmꢁ1): 3089,
1660 (C]N). HPLC: C4 column: tR ¼ 11.7 min, purity >99% C18
column: tR ¼ 20.5 min, purity >99%.
1.76e1.53 (m, 6H); 1.44 (s, 9H). 13C NMR (CDCl3, 75 MHz),
d (ppm):
155.1, 140.4, 128.3, 128.0, 126.9, 124.8, 79.4, 53.4, 49.9, 48.0, 39.3,
4.4.3. (10aS)-2-[2-(2-Pyridyl)ethyl]-1,5,10,10a-tetrahydroimidazo
[1,5-b]isoquinolin-3-imine dihydrochloride (3)
28.5, 26.7, 25.4, 19.3. MS (ESIþ): m/z ¼ 305.0 [M,H]þ found;
C
18H28N2O2 calculated m/z ¼ 305.2 [M,H]þ.
According to general method 2, 3 was obtained (chromatog-
raphy, CH2Cl2/methanol 90/10) as a white powder (0.10 g, 67%). 1H
4.3.11. tert-Butyl N-[2-(benzylamino)-1-methyl-ethyl]carbamate
(11b)
According to general method 2, 11b was obtained as a yellow oil
(0.286 g, 19%). Analyses similar to literature description [57].
NMR (CD3OD, 300 MHz),
d
(ppm): 8.84 (d, J ¼ 6.0 Hz, 1H); 8.64 (t,
J ¼ 9.0 Hz, 1H); 8.23 (d, J ¼ 6.0 Hz, 1H); 8.04 (t, J ¼ 9.0 Hz, 1H); 7.23
(s, 4H); 4.67 (AB system, J ¼ 15.0 Hz, Dn ¼ 75 Hz, 2H); 4.15e3.91 (m,
4H); 3.63 [AB part of ABX system (t, J ¼ 9.0 Hz, 1H) Dn ¼ 114 Hz];
3.56 (t, J ¼ 8.0 Hz, 2H); 2.99 [AB part of ABX system (d, J ¼ 15.0 Hz,
1H] and (t, J ¼ 9.0 Hz, 1H), Dn ¼ 51 Hz). 13C NMR (CD3OD, 75 MHz),
4.3.12. tert-Butyl N-[(1S)-1-[(benzylamino)methyl]-2-(4-tert-
butoxyphenyl)ethyl]carbamate (12b)
d
(ppm): 156.6, 152.9, 147.1, 141.4, 131.9, 129.7, 129.1, 128.1, 127.0,
According to general method 2, 12b was obtained as a yellow oil
126.8, 126.1, 125.7, 53.4, 52.6, 43.8, 44.2, 33.4. HRMS (ESIþ): m/
z ¼ 293.17595 [M,H]þ found; C18H20N4 calculated m/z ¼ 293.17607
[M,H]þ. Mp: 123.8 ꢀC. aD (20 ꢀC, CH3OH) ¼ ꢁ0.449ꢀ (0.500 mg/mL).
(0.252 g, 58%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.33e7.20 (m,
5H); 7.14e6.98 (m, 2H); 6.91e6.82 (m, 2H); 4.98 (br s, 1H);
3.94e3.84 (unresolved X part of ABX system, m, 1H); 3.77 (AB
system, J ¼ 13.1 Hz, Dn ¼ 26.8 Hz, 2H); 3.12e2.91 (unresolved AB
part of ABX system, m, 1H); 2.90e2.69 (unresolved AB part of ABX
system, m, 3H); 1.41 and 1.32 (2s, 19H). 13C NMR (CDCl3, 75 MHz),
IR,
n
(cmꢁ1): 3039, 1668 (C]N). HPLC: C4 column: tR ¼ 6.7 min,
purity >99% C18 column: tR ¼ 12.9 min, purity 98%.
4.4.4. (10aS)-2-(2-Morpholinoethyl)-1,5,10,10a-tetrahydroimidazo
[1,5-b]isoquinolin-3-imine dihydrochloride (4)
d
(ppm): 155.8, 153.7, 139.0, 132.8, 129.7, 128.5, 127.2, 124.1, 79.2,
78.2 53.2, 51.0, 38.5, 28.8, 28.4. MS (ESIþ): m/z ¼ 413.1 [M,H]þ
According to general method 2, 4 was obtained (chromatog-
found; C25H37N2O3 calculated m/z ¼ 413.3 [M,H]þ.
raphy, CH2Cl2/methanol 90/10) as a brown oil (0.282 g, 69%). 1H
NMR (CD3OD, 300 MHz),
d (ppm): 7.34e7.18 (m, 4H); 4.66 (AB
4.3.13. tert-Butyl N-[(1S)-3-(benzylamino)-1-[(4-methoxyphenyl)
methyl]-2-oxo-propyl]carbamate (13b)
system, J ¼ 16.0 Hz, Dn ¼ 70 Hz, 2H); 4.17e3.99 (m, 1H); 3.71 (t,
J ¼ 4.6 Hz, 4H); 3.67e3.48 (m, 4H); 3.03 [AB part of ABX system (dd,
J ¼ 15.0 and 3.7 Hz, 1H) and (dd, J ¼ 15.4 and 10.3 Hz, 1H),
Dn ¼ 51 Hz]; 2.69 (t, J ¼ 5.8 Hz, 2H); 2.60 (t, J ¼ 4.5 Hz, 4H). 13C NMR
According to general method 2, 13b was obtained as a yellow oil
(0.032 g, 22%). 1H NMR (CDCl3, 300 MHz),
d (ppm): 7.31e7.15 (m,
5H); 7.09 (d, J ¼ 8.6 Hz, 2H); 6.82 (d, J ¼ 9.5 Hz, 2H); 4.74 (br s, 1H);
3.89e3.78 (unresolved X part of ABX system, m, 1H); 3.77e3.68 (m,
5H); 2.80e2.65 (unresolved AB part of ABX system, m, 2H);
2.63e2.57 (unresolved AB part of ABX system, m, 2H); 1.75e1.66
(CD3OD, 75 MHz), d (ppm): 157.4, 132.0, 129.9, 129.1, 127.0, 126.8,
126.0, 66.4, 55.7, 53.5, 53.2, 43.7, 42.3, 30.7. HRMS (ESIþ): m/
z
¼
301.20265 [M,H]þ found; C17H25N4O calculated m/
z ¼ 301.20229 [M,H]þ. HPLC: C4 column: tR ¼ 12.3 min, purity >94%
C18 column: tR ¼ 4.7 min, purity 97%.
(m, 1H, NH); 1.43 (s, 9H). 13C NMR (CDCl3, 75 MHz),
d (ppm): 158.2,
155.7, 140.2, 130.3, 130.1, 128.4, 128.2, 127.0, 113.8, 79.8, 55.2, 53.8,
51.33, 42.9, 38.2, 28.4. MS (ESIþ): m/z ¼ 371.2 [M,H]þ found;
C22H31N2O3 calculated m/z ¼ 371.2 [M,H]þ.
4.4.5. (10aS)-2-(4-Phenylbutyl)-1,5,10,10a-tetrahydroimidazo[1,5-
b]isoquinolin-3-imine hydrochloride (5)
According to general method 2, 5 was obtained (chromatog-
4.4. Preparation of guanidine compounds 2e13
raphy, CH2Cl2/methanol 94/6) as a light brown oil (0.206 g, 82%). 1H
NMR (CD3OD, 300 MHz),
d (ppm): 7.29e7.13 (m, 9H); 4.62 ([AB
4.4.1. General method 3
system (dd, J ¼ 18.0 Hz, Dn ¼ 81 Hz, 2H)]; 4.03e3.97 [unresolved X
part of ABX system (m, 1H)]; 3.87 and 3.46e3.32 [AB part of ABX
system (t, J ¼ 9.0 Hz, 1H) and (m, 1H), Dn ¼ 144 Hz]; 3.46e3.39 (m,
2H); 2.95 [AB part of ABX system (dd, J ¼ 15.0 and 3.0 Hz, 1H) and
(dd, J ¼ 15.0 and 9.0 Hz, 1H), Dn ¼ 72 Hz]; 2.69 (t, J ¼ 9.0 Hz, 2H);
To a solution of appropriate secondary amine (1 eq.) in EtOH
(1.6 mL/mmol of amine), NaHCO3 (3 eq.) and BrCN (1.1 eq.) were
added. The mixture was stirred at room temperature for 5 h. The
mixture was diluted with H2O and extracted twice with CH2Cl2.
Combined organic layers were dried under MgSO4. The solution
was filtered and evaporated in vacuo. No further purification was
performed unless specified. The nitrile compound (1 eq.) was dis-
solved in 3 M HCl/dioxane (0.08 M) and stirred at room tempera-
ture overnight. Dioxane was evaporated in vacuo. Purification via
flash chromatography was performed.
1.83e1.60 (m, 4H). 13C NMR (CD3OD, 75 MHz),
d (ppm): 156.6, 141.8,
132.0, 129.9, 129.7, 128.8, 128.0, 127.3, 126.9, 126.8, 126.1, 125.5,
124.8, 53.1, 51.9, 45.4, 43.3, 35.0, 33.3, 28.0, 26.1. HRMS (ESIþ): m/
z ¼ 320.21259 [M,H]þ found; C21H26N3 calculated m/z ¼ 320.21212
[M,H]þ. aD (20 ꢀC, CH3OH) ¼ ꢁ0.499ꢀ (0.500 mg/mL). IR,
n
(cmꢁ1):
2929, 1664 (C]N). HPLC: C4 column: tR ¼ 12.7 min, purity 98% C18
column: tR ¼ 23.7 min, purity 98%.
4.4.2. (10aS)-2-Benzyl-1,5,10,10a-tetrahydroimidazo[1,5-b]
isoquinolin-3-imine monohydrochloride (2)
4.4.6. tert-Butyl (3S)-3-[(hexylamino)methyl]-3,4-dihydro-1H-
isoquinoline-2-carboxylate (6)
According to general method 2, 2 was obtained (chromatog-
raphy, CH2Cl2/methanol 94/6) as a white powder (0.13 g, 46%). 1H
According to general method 2, 6 was obtained (chromatog-
NMR (CD3OD, 300 MHz), d (ppm): 7.41e7.36 (m, 5H); 7.26e7.18 (m,
raphy, CH2Cl2/methanol 85/15) as an orange oil (228 mg, 88%). 1H

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V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
23
NMR (CD3OD, 300 MHz),
d
(ppm): 7.29e7.14 (m, 4H); 4.68 (AB
system, d, J ¼ 15.1 Hz, Dn ¼ 18.7 Hz, 1H]; 3.92e3.88 (m, 1H); 3.51
[unresolved AB part of ABX system (dd, J ¼ 12.3 and 9.0 Hz, 1H) and
(dd, J ¼ 15.3 and 9.2 Hz, 1H), Dn ¼ 246 Hz]; 3.87e3.73 (m, 1H); 3.08
(dd, J ¼ 9.0 and 3.1 Hz, 1H); 1.91e1.77 (m, 2H); 1.58e1.30 (m, 4H).
system, J ¼ 15.7 Hz, Dn ¼ 90.6 Hz, 2H); 4.03e3.94 (m, 2H);
3.64e3.32 (m, 3H); 2.97 [AB part of ABX system (dd, J ¼ 15.5 and
2.7 Hz, 1H) and (dd, J ¼ 15.5 and 10.0 Hz, 1H), Dn ¼ 87.7 Hz]; 1.66
(quin, J ¼ 6.9 Hz, 2H); 1.49e1.31 (m, 6H); 0.93 (t, J ¼ 6.2 Hz, 3H). 13
C
13C NMR (CD3OD, 75 MHz),
d (ppm): 156.0, 134.4, 128.7, 128.0;
NMR (CD3OD, 75 MHz),
d
(ppm): 156.6, 132.1, 130.1, 129.1, 127.0,
127.5, 59.5, 51.5, 47.8, 42.3, 29.7, 24.0, 22.2. HRMS (ESIþ): m/
z ¼ 230.16490 [M,H]þ found; C14H20N3 calculated m/z ¼ 230.16517
[M,H]þ. Mp: 188.2 ꢀC. aD (20 ꢀC, CH3OH) ¼ þ10.6ꢀ (0.500 mg/mL).
126.8, 126.2, 53.2, 52.0, 44.9, 43.9, 33.4, 31.3, 26.6, 25.9, 22.3, 13.1.
HRMS (ESIþ): m/z ¼ 272.21249 [M,H]þ found; C17H26N3 calculated
m/z ¼ 272.21212 [M,H]þ. HPLC: C4 column: tR ¼ 3.3 min, purity 98%
IR,
n
(cmꢁ1): 2941, 1660 (C]N). HPLC: C4 column: tR ¼ 9.0 min,
C
18 column: tR ¼ 26.9 min, purity 97%.
purity 98% C18 column: tR ¼ 16.6 min, purity >99%.
4.4.7. (4S)-1,4-Dibenzylimidazolidin-2-imine hydrochloride (7)
According to general method 2, 7 was obtained (chromatog-
raphy, CH2Cl2/methanol 95/5) as a white powder (19 mg, 27%). 1H
4.4.11. (4S)-1-Benzyl-4-methyl-imidazolidin-2-imine hydrochloride
(11)
According to general method 2, 11 was obtained (chromatog-
NMR (CD3OD, 300 MHz), d (ppm): 7.38e7.22 (m, 6H); 7.21e7.10 (m,
raphy, CH2Cl2/methanol 90/10) a white powder (42 mg, 53%). 1H
4H); 4.35 (dd, J ¼ 28.9 and 13.5 Hz, 2H); 4.29e4.21 (unresolved X
part of ABX system, m, 1H); 3.61 and 3.33e3.27 [AB part of ABX
system (ft, J ¼ 9.6 Hz, 1H) and (m, 1H), Dn ¼ 93 Hz]; 2.87 (d,
NMR (CD3OD, 300 MHz), d (ppm): 7.48e7.27 (m, 5H); 4.59 (br s,
1H); 4.42 (br s, 2H); 4.12e3.99 (unresolved X part of ABX system, m,
1H); 3.71 and 3.14 [AB part of ABX system (dd, J ¼ 18.9 and 9.5 Hz,
1H) and (dd, J ¼ 9.6 and 6.7 Hz, 1H) Dn ¼ 179.9 Hz); 1.25 (d,
J ¼ 5.9 Hz, 2H). 13C NMR (CD3OD, 75 MHz),
d (ppm): 157.9, 135.7,
134.2, 129.2, 128.8, 128.4, 127.9, 127.4, 126.7, 53.8, 51.1, 48.5, 39.9.
HRMS (ESIþ): m/z ¼ 266.16529 [M,H]þ found; C17H20N3 calculated
m/z ¼ 266.16517 [M,H]þ. Mp: 196.1 ꢀC. aD (20 ꢀC, CH3OH) ¼ ꢁ0.006ꢀ
J ¼ 6.0 Hz, 3H). 13C NMR (CD3OD, 75 MHz),
d (ppm): 158.0, 134.5,
128.8, 127.9, 127.5, 53.6, 48.9, 19.5. HRMS (ESIþ): m/z ¼ 190.13416
[M,H]þ found; C11H16N3 calculated m/z ¼ 190.13387 [M,H]þ. Mp:
(0.500 mg/mL). IR,
n
(cmꢁ1): 3060, 1668 (C]N). HPLC: C4 column:
194.9 ꢀC. aD (20 ꢀC, CH3OH) ¼ ꢁ0.045ꢀ (0.500 mg/mL). IR,
n
(cmꢁ1):
tR ¼ 13.1 min, purity >99% C18 column: tR ¼ 24.7 min, purity >99%.
3055, 1667 (C]N). HPLC: C4 column: tR ¼ 7.3 min, purity 98% C18
column: tR ¼ 8.0 min, purity >99%.
4.4.8. (4S)-1,4-Dibenzyl-3-methyl-imidazolidin-2-imine
hydrochloride (8)
4.4.12. 4-[[(4S)-1-Benzyl-2-imino-imidazolidin-4-yl]methyl]phenol
hydrochloride (12)
According to general method 2, 8 was obtained (chromatog-
raphy, CH2Cl2/methanol 95/5) a white powder (14 mg, 67%). 1H
According to general method 2, 12 was obtained (chromatog-
NMR (CD3OD, 300 MHz), d (ppm): 7.39e7.23 (m, 6H); 7.17e7.04 (m,
raphy, CH2Cl2/methanol 85/15) a brown solid (53 mg, 73%). 1H NMR
4H); 4.39 (AB system, J ¼ 15.7 Hz, Dn ¼ 38.9 Hz, 2H); 4.23e4.11
(unresolved X part of ABX system, m, 1H); 3.37 [AB part of ABX
system (t, J ¼ 9.7 Hz, 1H) and (dd, J ¼ 9.9 and 5.7 Hz, 1H),
Dn ¼ 91.7 Hz]; 3.10 (s, 3H); 2.94 [AB part of ABX system (dd, J ¼ 13.9
(CD3OD, 300 MHz), d (ppm): 7.33 (m, 3H); 7.06 (m, 2H); 6.98 (d,
J ¼ 8.5 Hz, 2H); 6.72 (d, J ¼ 8.5 Hz, 2H); 4.45 (AB system, J ¼ 15.8 Hz,
2H, Dn ¼ 42.9 Hz); 4.20 (unresolved X part of ABX system, m, 1H);
3.59 and 3.33e3.27 [AB part of ABX system (t, J ¼ 9.7 Hz, 1H) and
(m, 1H), Dn ¼ 259.7 Hz]; 2.82e2.66 (unresolved AB part of ABX
and 4.4 Hz, 1H) and (dd, J ¼ 7.1 and 6.8 Hz, 1H), Dn ¼ 61.9 Hz]. 13
C
NMR (CD3OD, 75 MHz),
d
(ppm): 157.4, 135.3, 134.2, 129.2, 128.7,
system, m, 2H). 13C NMR (CD3OD, 75 MHz),
d (ppm): 158.0, 156.3,
128.5,127.9, 127.3,126.9, 59.8, 49.4, 48.0 (CH2(d)); 36.8 (CH2(a)); 30.2
(CH3(1)). HRMS (ESIþ): m/z ¼ 280.18080 [M,H]þ found; C18H22N3
calculated m/z ¼ 280.18082 [M,H]þ. Mp: 244.5 ꢀC. aD (20 ꢀC,
134.2, 130.3, 128.7, 127.8, 127.2, 126.0, 115.1, 53.9, 50.9, 47.9, 38.9.
HRMS (ESIþ): m/z ¼ 282.15985 [M,H]þ found; C17H20N3O calculated
m/z ¼ 282.16009 [M,H]þ. Mp: ꢀC. aD (20 ꢀC, CH3OH) ¼ ꢁ0.014ꢀ
CH3OH) ¼ ꢁ0.098ꢀ (0.500 mg/mL). IR,
n
(cmꢁ1): 3024, 1664 (C]N).
(0.500 mg/mL). IR, n
(cmꢁ1): 3064, 1670 (C]N). HPLC: C4 column:
HPLC: C4 column: tR ¼ 10.1 min, purity >99% C18 column:
tR ¼ 10.2 min, purity 99% C18 column: tR ¼ 15.8 min, purity >99%.
tR ¼ 4.5 min, purity >99%.
4.4.13. (4S)-1-Benzyl-4-[(4-methoxyphenyl)methyl]imidazolidin-2-
imine hydrochloride (13)
4.4.9. (4S)-1-Benzyl-4-[(4-fluorophenyl)methyl]imidazolidin-2-
imine hydrochloride (9)
According to general method 2, 13 was obtained (chromatog-
According to general method 2, 9 was obtained (chromatog-
raphy, CH2Cl2/methanol 90/10) a brown solid (14 mg, 67%). 1H NMR
raphy, CH2Cl2/methanol 90/10) a white powder (217 mg, 90%). 1H
(CD3OD, 300 MHz),
d
(ppm): 7.39e7.31 (m, 5H); 7.09 (d, J ¼ 8.6 Hz,
NMR (CD3OD, 300 MHz),
d
(ppm): 7.41e7.28 (m, 3H); 7.26e7.17 (m,
2H); 6.83 (d, J ¼ 6.6 Hz, 2H); 4.45 (AB system, 2H, J ¼ 15.8 Hz,
Dn ¼ 37.3 Hz); 4.26e4.19 (unresolved X part of ABX system, m, 1H);
3.79 (s, 3H); 3.61 [AB part of ABX system (ft, J ¼ 9.7 Hz, 1H) and (m,
1H), Dn ¼ 90 Hz)]; 2.80 (unresolved AB part of ABX system, m, 2H).
2H); 7.17e7.09 (m, 2H); 7.06e6.95 (m, 2H); 4.44 [AB system,
J ¼ 16.1 Hz, Dn ¼ 41 Hz, 2H); 4.32e4.19 (unresolved X part of ABX
system, m, 1H); 3.62 and 3.34e3.24 [unresolved AB part of ABX
system (t, J ¼ 11.2 Hz, 1H) and (m, 1H), Dn ¼ 108 Hz]; 2.94e2.77
(unresolved AB part of ABX system, m, 2H). 13C NMR (CD3OD,
13C NMR (CD3OD, 75 MHz),
d (ppm): 158.9, 157.9, 134.2, 130.2, 128.7,
127.9, 127.4, 127.3, 113.8, 54.3, 53.9, 50.9, 48.4, 48.1, 47.9, 38.9. HRMS
(ESIþ): m/z ¼ 296.17555 [M,H]þ found; C17H20N3O calculated m/
z ¼ 296.17574 [M,H]þ. Mp: ꢀC. aD (20 ꢀC, CH3OH) ¼ ꢁ0.045ꢀ
75 MHz),
d
(ppm): 163.7, 160.4 (JCeF ¼ 242.1 Hz); 157.9, 134.2, 131.6,
131.1, 131.0, 128.7; 127.9, 127.5, 115.2, 114.9, 53.7, 50.9, 48.5, 38.8.
HRMS (ESIþ): m/z ¼ 284.15576 [M,H]þ found; C17H19FN3 calculated
(0.500 mg/mL). IR, n
(cmꢁ1): 3064, 1670 (C]N). HPLC: C4 column:
m/z
¼
284.15575 [M,H]þ. Mp: 244.5 ꢀC. aD (20 ꢀC,
tR ¼ 13.3 min, purity 99% C18 column: tR ¼ 8.0 min, purity >99%.
CH3OH) ¼ ꢁ0.072ꢀ (0.500 mg/mL). HPLC: C4 column: tR ¼ 11.0 min,
purity >99% C18 column: tR ¼ 19.5 min, purity >99%.
4.5. In vitro testing
4.4.10. (8aS)-2-Benzyl-1,5,6,7,8,8a-hexahydroimidazo[1,5-a]
pyridin-3-imine hydrochloride (10)
4.5.1. Displacement binding assays
Competition binding curves of the A2A receptor antagonist [3H]-
ZM24135 by the designed A2A antagonists described above, were
performed as before [58] in Human HEK293 A2AR membranes
According to general method 2, 10 was obtained (chromatog-
raphy, CH2Cl2/methanol 90/10) a white powder (130 mg, 29%). 1H
NMR (CD3OD, 300 MHz),
d
(ppm): 7.47e7.28 (m, 5H); 4.59 (AB
(Perkin Elmer). 0.5 mL of membranes (0.5 U of A2AR) were incubated

ꢀ
V. Moas-Heloire et al. / European Journal of Medicinal Chemistry 106 (2015) 15e25
24
with [3H]-ZM24135 (2 nM) and increasing concentrations of the
designed A2AR antagonists (0e600 nM) in a final volume of 300
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mL
in the presence of 1 U/mL of adenosine deaminase (Roche). All
samples were assayed in duplicate. Non-specific binding was
determined for each assay in the presence of the antagonist ZM-
24135 (8.3 nM). Microplates were incubated for 1 h at room tem-
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The human neuroblastoma cell line (SY5Y) was cultured in
DMEM (Dulbecco's Modified Eagle Medium) (Gibco) supplemented
with 2 mM L-glutamine, 100 mg/ml streptomycin, 100 IU/mL peni-
cillin, 1 mM non-essential amino acids and 10% (v/v) heat-
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Acknowledgments
We express our thanks to Mariam Lamarti, Phillip James
Brennan and Alice Cao for their contribution in organic synthesis
ꢀ
and Amelie Barczyk for some in vitro cytotoxicity experiments. The
ꢀ
300 MHz NMR facilities were funded by the Region Nord-Pas de
ꢁ
Calais (France), the Ministere de la Jeunesse, de l'Education Natio-
ꢀ
nale et de la Recherche (MJENR) and the Fonds Europeens de
ꢀ
ꢀ
Developpement Regional (FEDER).
This work was supported by Lille 2 University, ANR «Adoratau»,
PRES Univ Lille Nord de France. Valeria Moas Heloire is the recipient
of a fellowship from Lille 2 University.
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Appendix A. Supporting information
Supporting information related to this article can be found at
http://dx.doi.org/10.1016/j.ejmech.2015.10.030.
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