Synthesis and biological evaluation of novel imidazole-containing macrocycles

Article abstract of DOI:10.1016/j.tet.2010.04.070

A new family of compounds made of a 5-aryl-1H-imidazole motif included in a macrocycle has been designed and synthesized. The synthesis of the imidazole core makes use of our previously developed method for the regioselective preparation of 1,2,5-trisubstituted imidazoles while the construction of the macrocycle is based on a three steps sequence: S_NAr, Suzuki coupling, and RCM reaction. Biological evaluation of synthesized imidazole-containing macrocycles revealed that they display actual binding activity toward A₃ adenosine (h) receptor, dopamine D₁ (h) receptor, chloride channel (GABA-gated), and choline transporter (h) CHT1.

Full text of DOI:10.1016/j.tet.2010.04.070

Tetrahedron 66 (2010) 4515e4520
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis and biological evaluation of novel imidazole-containing macrocycles
,
,
Prosper Nshimyumukiza a b, Emilie Van Den Berge a, Bruno Delest a b, Tatjana Mijatovic c,
Robert Kiss c, Jacqueline Marchand-Brynaert a, Raphaël Robiette a
,
*
a Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
b Unibioscreen SA, 40 avenue Joseph Wibran, B-1070 Brussels, Belgium
c Institute of Pharmacy, Université Libre de Bruxelles, Campus Plaine CP205-1, Blvd du Triomphe, B-1050 Brussels, Belgium
a r t i c l e i n f o
a b s t r a c t
Article history:
A new family of compounds made of a 5-aryl-1H-imidazole motif included in a macrocycle has been
designed and synthesized. The synthesis of the imidazole core makes use of our previously developed
method for the regioselective preparation of 1,2,5-trisubstituted imidazoles while the construction of the
macrocycle is based on a three steps sequence: SNAr, Suzuki coupling, and RCM reaction. Biological
evaluation of synthesized imidazole-containing macrocycles revealed that they display actual binding
activity toward A3 adenosine (h) receptor, dopamine D1 (h) receptor, chloride channel (GABA-gated), and
choline transporter (h) CHT1.
Received 10 February 2010
Received in revised form 12 April 2010
Accepted 16 April 2010
Available online 21 April 2010
Keywords:
Central nervous system
Conformational flexibility
Imidazole
Ó 2010 Elsevier Ltd. All rights reserved.
Inflammation
Macrocycles
( )n
( )n
Me
O
O
1. Introduction
Me
O
N
N
R
N
N
O
4(5)-Aryl-1H-substituted imidazoles are central substructures
of many compounds exhibiting biological and pharmacological
properties.1,2 Hence, this motif is found in numerous drugs, such as
anti-inflammatory agents, kinase inhibitors, antagonists of CB1
cannabinoid, and glucagon receptors, antibacterial agents. For
these reasons, the synthesis of new structures containing this
framework has attracted much attention from both academia and
industry.
2
2
1
R
1
R
R
1
2
Recently, we reportedthesynthesisofnovellargering1,3-bridged
2-azetidinones related to the carbapenem family.3 This combined
experimental and theoretical study showed that the inclusion of the
azetidinonemotifina macrocycleallows actingonitsconformational
flexibility and hence investigating the importance of geometrical
factors on biological properties.4
This prompted us to consider the synthesis and the biological
evaluation of novel 5-aryl-1H-imidazole-containing macrocycles.
The envisioned structures (1) consist in large rings (ꢀ15 atoms)
incorporating a 5-aryl-1H-imidazole motif by connection at C2 and
ortho-aryl positions (Fig. 1).
HO OH
B
( )n
Me
O
SO Ph
2
O
Me
N
N
N
N
+
1
R
I
I
2
R
5
3
4
Br
OH
Our planned strategy for the synthesis of these macrocycles
MsO
(1) is based on the ring closing metathesis (RCM) reaction5 of
1
R
7
2
R
6
* Corresponding author. E-mail address: raphael.robiette@uclouvain.be (R.
Robiette).
Figure 1. Designed strategy for the synthesis of imidazole-containing macrocycles 1.
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.04.070

4516
P. Nshimyumukiza et al. / Tetrahedron 66 (2010) 4515e4520
preparation, on gram-scale, in four steps with a good overall yield
PhS
O
O
NMe
1) nBuLi, THF, -78°C
2
(58%) (Scheme 1). This intermediate in hand (it can be stored for
months), we subjected it to further functionalization in positions 2
and 5.
NMe
S
2
N
N
S
N
N
O
O
2) PhSSPh, THF
-78°C to RT
8
9
Placing of the first alkene chain at position 2 of the imidazole
could be done by aromatic nucleophilic substitution of the phenyl
sulfone group by an alkenoxide (Scheme 2). Under classical heating
bath conditions the reaction necessitated extended reaction times
(>24 h) and led to low yields (<50%) whatever the nature of the
counterion (Naþ, Kþ, Liþ). However, we found that microwave
heating allows high conversion after only 6.5 h.7 In order to
investigate the influence of the size of the macrocycle, the reaction
was performed with 5-buten-1-ol and 7-hexen-1-ol, leading to 12
and 120 in 78% and 76% yield, respectively. The next step in our
strategy is the substitution of the iodo atom by an aryl group using
a Suzuki coupling.
91%
1) nBuLi, THF
-78°C
91%
2) I2, THF
-78°C to RT
SPh
N
PhS
N
O
1)
MeOTf, CH Cl , RT
NMe
2
2
2
Me
S
N
N
O
I
2) MeBuNH, CH3CN,
I
85°C
71 %
10
11
mCPBA
98%
N
In order to explore substituent effects on the biological activities,
a variety of boronic acids were prepared (variations on R1 and R2).
Theselatterwereeasilyobtainedfromcorresponding(commercially
available) substituted bromophenols according to a two steps pro-
cedure (Scheme 3). In the first step, alkylation of phenols allows
introducing the alkene chain (6/14). Then, the obtained ethers are
subjected to a halogenemetal exchange and added to triisopro-
pylborate to yield, after hydrolysis, the corresponding boronic acids
(4aee).8
CH2Cl2, RT
SO Ph
2
Me
N
I
5
Scheme 1. Synthesis of key intermediate 5.
The Suzuki coupling between the synthesized boronic acids
(4aee) and 5-iodo-1H-imidazoles 12 and 120, under microwave
heating, leads to the desired 1,2,5-trisubstituted imidazoles 2aee
and 20a in good yields (see Scheme 2).9
1,2,5-trisubstituted imidazoles 2. These intermediates could be
obtained by successive functionalization of imidazole 5: aromatic
nucleophilic substitution (SNAr) will allow placing the first alkene
chain in position 2 while substitution at carbon 5 by Suzuki
coupling will provide diene substrate 2. In order to explore the
influence of aryl substitution on biological activities, different aryl
boronic acids have been envisaged (variations on R1 and R2). The
size of the macrocycle has also been varied (n¼1 or 3).
These dienes (2aee and 20a) were then subjected to the last key
step of our synthesis, the RCM reaction. Under heating in the
presence of second generation Grubbs catalyst, the dienes furnish
macrocycles 13aee and 130a as ca. 50/50 mixtures of E and Z iso-
mers (determined by 1H NMR) (see Scheme 2).10 Alkenes were not
isolated but directly hydrogenated to provide macrocycles 1aee.
The moderate yields (19e49% over the two steps) are mainly due to
low conversion in the RCM reaction. All our attempts to improve
this step by using other catalysts (Grubbs first generation, Hoveyda,
etc.) or additives, such as Ti(Oi-Pr)4, were unsuccessful.
Thus, the designed aryl imidazole-containing macrocycles (1aee
and 10a) were synthesized in eight steps (longest linear sequence) in
8e16% overall yield. To investigate the importance of the C2 and
ortho aryl substitution on the biological activity, we have also syn-
thesized compounds 15 and 16 (Scheme 4).
2. Results and discussion
2.1. Synthesis
The first step of our synthesis is the preparation of intermediate
5. We have recently reported a divergent and regioselective method
for the synthesis of 1,2,4- and 1,2,5-trisubstituted imidazoles.6
Application of this methodology to imidazole
5 allows its
HO OH
B
( )n
HO
O
( )n
O
NaH
1
( )n
O
R
SO Ph
2
Me
O
4a-e
N
N
2
( )n
NaO
R
Me
N
Me
N
N
N
Pd(PPh3)4 (cat.)
Na2CO3, DME, 80°C
THF, 6.5 h
80°C MW
I
I
12 n = 1 78%
12' n = 3 76%
2
5
1
R
R
2a-e 75-97 %
76 %
2'a
a R1 = H, R2 = H
GrubbsG2 (5 mol%)
DCE, 100°C
R
1 = Me, R2 = H
b
c R1 = OMe, R2 = H
d R1 = F, R2 = H
e R1 = H, R2 = F
( )n
Me
( )n
O
O
Me
O
H2/Pd (5 mol%)
N
N
N
N
R
O
AcOEt/EtOH (1/1)
RT, 3h
2
2
1
1
R
R
R
1a-e 19-31%
1'a 49%
13a-e
13'a
Scheme 2. Synthesis of macrocycles 1aee.

P. Nshimyumukiza et al. / Tetrahedron 66 (2010) 4515e4520
4517
many clinically important drugs.16 Drugs that enhance synaptic
gamma-aminobutyric acid (GABA)ergic neurotransmission are
widely utilized in the clinical setting.
Choline plays an important role in the synthesis of the mem-
brane phospholipid components of the cell membranes. Abnormal
choline transport and metabolism have been implicated in a num-
ber of neurodegenerative disorders such as Alzheimer’s and Par-
kinson’s disease.17,18
In summary, these four hinted targets present sustained phar-
macological interest and therefore new compounds from this series
could generate novel lead compounds by means of pursuing of the
methodological approach we have initiated here.
Thus, all the synthesized macrocycles, as well as several key
intermediates in their synthesis, were submitted to specific binding
analysis on these four targets (Table 1). Interestingly, these assays
show that most of our compounds conserved the highly binding
activity toward these receptors. Results are given in percentages of
inhibition of control specific binding.
HO
MsCl/Et3N
CH2Cl2
quant.
MsO
Br
Br
OH
7
O
DBU, Bu4NI
DMF, 70°C
R1
R1
R2
6a-e
R2
14a-e
89-99%
1) n-BuLi, THF,
1
2
a
R = H, R = H
-78°C
b R1 = Me, R2 = H
c R1 = OMe, R2 = H
d R1 = F, R2 = H
e R1 = H, R2 = F
2) B(Oi-Pr)3
3) HCl 1N
HO OH
B
O
Table 1
R1
Specific binding tests (concentration¼10
Compound % Inhibition of control specific binding
Adenosine A3 Dopamine Cl-channel
mM)
R2 4a-e
40-84%
Choline transporter
(h) receptor receptor D1 (h) (GABA-gated) (h) (CHT1)
Scheme 3. Synthesis of boronic acids 4aee.
5
27
52
96
93
96
96
94
96
96
65
84
94
73
95
88
99
ꢁ11
23
55
84
93
54
51
88
87
70
69
97
56
90
80
99
2
3
0
ꢁ6
28
16
75
63
65
73
81
38
52
87
46
47
43
98
15
16
2a
2b
2c
2d
2e
20a
13a
1a
1b
1c
1d
1e
10a
80
86
63
79
58
72
74
32
52
67
50
49
54
73
HO OH
B
SO2Ph
Me
SO2Ph
Me
OR
N
N
N
N
OR
Pd(PPh3) (cat.)
Cs2CO3, DMF, 80°C
I
5
R = H (15)
85%
89%
C6H11 (16)
Scheme 4. Synthesis of 14 and 15.
2.2. Biological evaluation
In order to optimally assess the ‘biological diversity’ of these
early discovery compounds, we then submitted compound 1a to
the CEREP’s Diversity Profile (CEREP, Paris, France). The diversity
profile of compound 1a has been evaluated by performing test
binding against a panel of 71 receptors and 16 enzymes (see
Experimental section). The obtained data showed that four tar-
gets were hinted by this compound: adenosine A3 adenosine (h)
receptor (A(3)AR), dopamine D1 (h) receptor (DA D1), Clꢁ channel
(GABA-gated), and choline transporter (h) CHT1. These results
suggest a possible activity and application of this compound in
the central nervous system (CNS) and for inflammatory affection,
as briefly summarized below.
The panel of compounds tested enabled us to draw some very
preliminary hypotheses. First, the binding affinity patterns of 5, 14,
and 15 (as compared to 1a and 2a) suggests the importance of the
5-aryl and, to a lower extent, 2-alkoxy substituents in the biological
activity.
A careful analysis of results for 1aee reveals the rather low in-
fluence of aryl substitution (R1, R2) on the binding properties of the
macrocycles toward A3 (h) receptor and Clꢁ channel (GABA-gated).
For the two other targets, dopamine D1 (h) receptor and choline
transporter (h) CHT1, significant variations are observed with the
methyl substituted macrocycle (1b) displaying the best activities
(better than its non-substituted analog 1a).
Adenosine receptors (ARs) are major targets of caffeine and
theophylline. Adenosine has potent effects on both the cardiovas-
cular and immune systems. Thus, A(3)AR agonists may be a new
family of drugs to be developed as potent inhibitors of autoim-
mune-inflammatory diseases.11
Dopamine is thought to play a role in such a diverse array of
processes as motor control, neuroendocrine and cardiovascular
regulation as well as in regulation of cognition, emotion and
reward.12e15 Although the first DA D1 receptor selective ligand was
introduced more than two decades ago, clinically useful D1 receptor
selective ligands are rare.
The influence of macrocyclization can also be investigated by
comparing binding properties of 1aee and 2aee. This analysis
shows that formation of the 15-membered macrocycle (n¼1) has
no, or a negative, effect on the binding activity toward A(3)AR, DA
D1, and Clꢁ channel (GABA-gated).19 This slight decrease in binding
activities can probably be accounted for by the lower flexibility of
macrocyclic compounds. Indeed, an increase in binding activity is
observed by reduction of the double bond (13a to 1a). Interestingly,
for choline transporter target, the opposite trend is observed in the
case of non-substituted (1a/2a) and 4-methylated (1b/2b)
derivatives: in these cases, binding activity is significantly
increased by macrocyclization. For the three other substrates
(1cee/2cee), the activity toward choline transporter target
decreases with cyclization.
GABAA receptors are chloride ion channels that mediate fast
synaptic transmission. GABAA receptors are the major inhibitory
neurotransmitter receptors in the brain and the site of action of

4518
P. Nshimyumukiza et al. / Tetrahedron 66 (2010) 4515e4520
The importance of flexibility is further illustrated by the increase
phenylsulfonylimidazole (5, 725 mg, 2.08 mmol,1 equiv) in dry THF
(35 mL). The reaction mixture was transferred into a sealed tube
and heated under microwave for 6.5 h at 80 ꢂC. Ethyl acetate
(50 mL) and 10% sodium hydroxide solution (30 mL) were succes-
sively added. The organic phase was further washed twice with
a 10% solution of sodium hydroxide (30 mL). Combined aqueous
phases were extracted with ethyl acetate (20 mL). The combined
organic phases were washed with brine, dried over MgSO4, and
concentrated under reduced pressure. The crude product was
purified by flash chromatography over silica.
in biological activities observed with the enlargement of the size of
the macrocycle (n¼1 (1a) to n¼3 (10a)). For 17-membered macro-
cycle, cyclization is found to be beneficial for binding affinity toward
the four targets; macrocycle 10a displaying the higher binding
activity toward the four identified targets among all synthesized
compounds.
Given the high binding affinity displayed by the macrocycles
and the pharmacological interest of the four hinted targets, we
went further and determined the IC50 values for the more potent
compound (10a) as well as for the corresponding non-cyclized
product (20a) (Table 2). The IC50 values for these compounds
confirm their high binding activities and highlight the interest
presented by this novel family of compounds. A comparison of
the IC50 values obtained for 10a and 20a corroborates also the
beneficial character of the macrocyclisation on the binding
affinity.
4.1.2. General procedure for alkylation of bromophenols (6/14). To
a solution of 2-bromophenol (0.75 mL, 1.12 g, 6.47 mmol) in anhy-
drous DMF (10 mL) were successively added, under argon,
1,8-diazabicyclo[5.4.0]undec-7-ene (1.48 mL, 1.51 g, 9.70 mmol,
1.5 equiv),
hex-5-en-1-yl
methanesulfonate20
(7,
1.5 g,
8.42 mmol, 1.3 equiv), and tetra-n-butylammonium iodide (73 mg,
0.20 mmol, 0.03 equiv). The mixture was heated at 70 ꢂC for 7 h and
then stirred at room temperature overnight. The solvent was re-
moved under reduced pressure and the residue was taken up in
100 mL of ether. Water (15 mL) and 5 mL of HCl 1 M were succes-
sively added. The phases were separated and the organic phase was
washed with water (2ꢃ20 ml). The combined aqueous phases were
extracted with ether (2ꢃ30 ml). The organic phases were combined,
dried over MgSO4, and concentrated under vacuum. The crude
product was purified by flash chromatography using cyclohexane/
ethyl acetate 95/5 as eluent.
Table 2
IC50 values for 20a and 10a
Compound IC50
Adenosine A3 Dopamine
(m
M)a
Cl-channel
Choline transporter
(h) receptor receptor D1 (h) (GABA-gated) (h) (CHT1)
20a
10a
1.2
0.85
6.5
1.1
7.3
7.2
3.3
3.2
a
Each experiment was run in duplicate and the values shown are the average of
the two (see Experimental section for full details).
4.1.3. Characterization of 2-bromo-1-(hex-5-en-1-yloxy)benzene
3. Conclusion
(11a). Colorless oil; yield: 1.47 g (91%); 1H NMR (300 MHz, CDCl3):
d
¼7.53 (dd, J¼1.6, 7.9 Hz, 1H), 7.24 (ddd, J¼1.6, 7.4, 8.3 Hz, 1H), 6.88
In conclusion, we have designed and synthesized a series of novel
5-aryl imidazole-containing macrocycles. The first part of our syn-
thesis makes use of the method we recently developed for the
regioselective synthesis of 1,2,5-trisubstituted imidazoles, which
allowspreparing 5 on largescale. Our strategyfor the construction of
the macrocycle is based on a three steps sequence: SNAr, Suzuki
coupling, and RCM reaction. This method allowed preparing a vari-
ety of novel macrocyclic substrates in eight steps in good overall
yields.
(dd, J¼1.3, 8.3 Hz, 1H), 6.82 (dt, J¼1.4, 7.6 Hz, 1H), 5.89e5.78 (m,
1H), 5.01e4.99 (m, 2H), 4.03 (t, J¼6.4 Hz, 2H), 2.20e2.10 (m, 2H),
1.90e1.80 (m, 2H), 1.70e1.60 ppm (m, 1H); 13C NMR (75 MHz,
CDCl3):
d
¼155.6, 138.7, 133.5, 128.5, 121.8, 114.9, 113.3, 112.4, 69.1,
33.5, 28.7, 25.4 ppm; IR:
n
¼3074, 2941, 2858, 1535,1500, 1491, 1369,
1244, 1142, 912 cmꢁ1
; MS (CI) m/z: 254; HRMS calcd for
C12H15O79Br: 254.0301, found: 254.0314.
4.1.4. General procedure for the synthesis of boronic acids (14/4). In
a flame-dried two-neck round-bottomed flask was introduced,
under argon, 2-(hex-5-enyloxy)bromobenzene (14a, 1.3 g,
5.1 mmol, 1 equiv) and 20 mL of anhydrous THF. The solution
was then cooled to ꢁ78 ꢂC and nBuLi 2.5 M in hexanes (2.65 mL,
6.63 mmol, 1.3 equiv) was added dropwise. The resulting solu-
tion was stirred for 1 h at ꢁ78 ꢂC and triisopropylborate (2.4 mL,
1.96 g, 10.02 mmol, 2.0 equiv) was then added dropwise at
ꢁ78 ꢂC. The mixture was allowed to warm up slowly to room
temperature without removing the cooling bath and stirred
overnight. Ethyl acetate (10 mL) was added to the suspension
and hydrogen chloride 1 N was added until pH¼1 (about 7 mL).
The two phases were separated and the aqueous phase was
extracted with ethyl acetate (3ꢃ20 mL). The organic phases were
combined and washed with brine, dried over MgSO4, filtered,
and evaporated under reduced pressure. The pale yellow oil was
purified by flash chromatography with cyclohexane/ethyl acetate
85/15 as eluent.
Biological evaluation of all synthesized macrocycles, as well as of
key intermediates in their synthesis, has been performed. These
assays revealed that synthesized 5-aryl imidazole-containing mac-
rocycles display significant binding activity toward A3 adenosine (h)
receptor, dopamine D1 (h) receptor, Clꢁ channel (GABA-gated), and
cholinetransporter(h)CHT1. These receptors areimportant actors in
the CNS and inflammation and theirligands could play major roles in
the treatments of diverse neurological and inflammatory disorders.
4. Experimental section
4.1. Synthesis
General procedures and key spectroscopic data are reported
below for the non-substituted (R1, R2¼H) macrocycle (1a) with full
data, for all other derivatives, in the Supplementary data. Purity of
all tested compounds has been determined by HPLC. Purity is >98%,
unless mentioned otherwise.
Synthesis and characterization of 5 and 12 were previously
4.1.5. Characterization of 2-(hex-5-en-1-yloxy)phenylboronic acid
reported.6
(4a). Colorless oil; yield: 945 mg (84%); 1H NMR (300 MHz, CDCl3):
d
¼7.87 (dd, J¼7.3, 1.7 Hz, 1H), 7.45e7.40 (m, 1H), 7.03 (t, J¼7.3 Hz,
4.1.1. General procedure for SNAr (5/12). Alcohol (5 equiv) was
added to a solution of sodium hydride (383 mg of a 60 wt % sus-
pension in mineral oil, 9.58 mmol, 4.6 equiv) in dry THF (7 mL),
under argon. The solution was stirred until no more gas evolution
was observed and then added to a solution of 1-methyl-5-iodo-2-
1H), 6.90 (d, J¼8.3 Hz, 1H), 6.04 (s, 2H), 5.89e5.75 (m, 1H),
5.08e4.98 (m, 2H), 4.09 (t, J¼6.6 Hz, 2H), 2.19e211 (m, 2H),
1.90e1.80 (m, 2H), 1.65e1.55 ppm (m, 2H); 13C NMR (300 MHz,
CDCl3):
28.7, 25.4 ppm; IR:
d
¼164.1, 138.2, 137.0, 132.9, 121.3, 115.3, 110.9, 68.3, 33.4,
n
¼3409, 3074, 2926, 2854, 1641, 1599, 1576,

P. Nshimyumukiza et al. / Tetrahedron 66 (2010) 4515e4520
4519
1487, 1448, 1340, 1225, 910 cmꢁ1; MS (CI) m/z: 220, 219; HRMS
MS (ESI) m/z: 301; HRMS calcd for C18H25N2O2: 301.1916, found:
calcd for C12H17BO3: 220.1265, found: 220.1265.
301.1919.
4.1.6. General procedure for Suzuki coupling (12/2). Tetrakis(tri-
phenylphosphino)palladium (24.9 mg, 0.03 equiv) and imidazole
12 (200 mg, 0.719 mmol, 1 equiv) in dimethoxyethane (2 mL) were
introduced in a microwave tube. Boronic acid (1.1 equiv) in dime-
thoxyethane (2 mL), water (2 mL), and an aqueous solution of
sodium carbonate (20%, 1.2 mL, 3 equiv) were successively added.
The resulting mixture was then degassed for 30 min by means of
a flow of argon and placed in a microwaves oven at 105 ꢂC and
200 W for 1 h. Ethyl acetate (50 mL) and water (25 mL) were added.
The phases were separated and the aqueous phases were extracted
with ethyl acetate (25 mL). The organic phases were combined,
washed with a saturated aqueous solution of NaCl (25 mL), dried
over MgSO4, and concentrated under reduced pressure. The crude
product was purified by flash chromatography with cyclohexane/
ethyl acetate 85/15 as eluent.
4.1.11. General procedure for formation of fumaric salts. The imidaz-
ole compound (1 equiv) was dissolved in ethanol (0.1 M). A solution
of fumaric acid (1 equiv) in ethanol (0.05 M) was added. The mix-
ture was stirred overnight and then concentrated under reduced
pressure. The correct 1:1 ratio was checked by 1H NMR.
4.2. Biological assays
Assays have been performed on fumaric salts (see above). Purity
of all tested compounds has been determined by HPLC. Purity is
>98%, unless mentioned otherwise. The Diversity Profile was per-
formedwith 10 mM ofcompound1a byCEREP (France). The Diversity
profile is composed of 71 receptor binding and 16 enzyme assays.
The 87 assay panel is broadly defined with roughly an equal number
of selective, central and peripheral therapeutically relevant targets.
The lists of all targets and their reference ligands used as controls, as
well as experimental conditions, could be obtained at CEREP’s web
site.21 Following the analysis of the data obtained in the first set of
results, all synthesized compounds were analyzed (by CEREP,
France) for their binding activity toward four targets hinted by1a. All
compounds (test and reference) were analyzed in duplicate.
The specific ligand binding to the receptors is defined as the
difference between the total binding and the nonspecific binding
determined in the presence of an excess of unlabeled ligand. The
results are expressed as a percent of control specific binding
((measured specific binding/control specific binding)ꢃ100) and as
a percent inhibition of control specific binding (100ꢁ((measured
specific binding/control specific binding)ꢃ100)) obtained in the
presence of tested compound.
4.1.7. Characterization of 2-(but-3-en-yloxy)-5-[2-(hex-5-en-1-
yloxy)phenyl]-1-methyl-1H-imidazole (2a). Yellow oil; yield:
176 mg (75%); Purity¼91%; 1H NMR (300 MHz, CDCl3):
¼7.33 (td,
d
J¼8.2, 1.5 Hz, 1H), 7.25 (dd, J¼7.5, 1.5 Hz, 1H), 6.98 (dt, J¼7.4, 1.5 Hz,
1H), 6.94 (d, J¼8.2 Hz, 1H), 6.62 (s, 1H), 5.97e5.71 (m, 2H);
5.20e4.94 (m, 4H); 4.46 (t, J¼6.7 Hz, 2H), 3.97 (t, J¼6.6 Hz, 2H), 3.24
(s, 3H), 2.61e2.58 (m, 2H), 2.10e2.03 (m, 2H), 1.79e1.70 (m, 2H),
1.52e1.42 ppm (m, 2H); 13C NMR (75 MHz, CDCl3):
138.5, 134.4, 132.1, 129.6, 126.6, 121.7, 120.8, 120.0, 117.2, 114.9, 112.2,
d
¼156.9, 153.3,
68.45, 68.41, 33.7, 33.4, 29.5, 28.7, 25.4 ppm; IR:
n
¼2924, 2860,
1535, 1500, 1370, 1248, 1030, 735 cmꢁ1; MS (APCI) m/z: 327; HRMS
calcd for C20H27N2O2: 327.2073, found: 327.2064.
4.1.8. General procedure for RCM reaction (2/13). Diene 2 (225 mg,
1 equiv)and1,2-dichloroeethane(140 ml) wereintroducedin a flask
under argon. The mixture was heated at reflux and Grubbs catalyst
(second generation) (26.8 mg, 0.315 mmol, 0.05 equiv) was added.
The IC50 values(concentrationcausingahalf-maximalinhibitionof
control specific binding) and Hill coefficients (nH) were determined by
non-linear regression analysis of the competition curves generated
with mean replicate values using Hill equation curve fitting Y¼Dþ
[(AꢁD)/(1þ(C/C50
)
nH)], where Y¼specific binding, D¼minimum spe-
After 24 h,
a second fraction of Grubbs catalyst (13.4 mg,
0.158 mmol, 0.025 equiv) was added. After 24 h, the mixture was
cooled down to room temperature and potassium isocyanoacetate20
(39 mg) was added. After 1 h of stirring, the solvent was evaporated.
The crude product was purified by flash chromatography over silica
with cyclohexane/ethyl acetate 75/25 as eluent.
cific binding, A¼maximum specific binding, C¼compound concen-
tration, C50¼IC50, and nH¼slope factor. This analysis was performed
using a software developed at CEREP (Hill software) and validated by
comparison with data generated by the commercial software
SigmaPlotÒ 4.0 for WindowsÒ (Ó 1997 by SPSS Inc.).
The inhibition constants (Ki) were calculated using the Cheng
Prusoff equation(Ki¼IC50/(1þ(L/KD)), where L¼concentration of
radioligand in the assay, and KD¼affinity of the radioligand for the
receptor).
4.1.9. General procedure for hydrogenation (13/1). Pd/C 10% cat-
alyst (24 mg, 0.0222 mmol, 0.05 equiv) was added to a solution of
imidazole 13 (145 mg, 0.442 mmol, 1 equiv) in 20 mL of a 1:1
mixture of ethanol and ethyl acetate. The resulting suspension was
degassed by means of a flow of argon for 30 min and then stirred
under hydrogen atmosphere for 3 h at room temperature. The
suspension was filtered through a Celite pad, washed with ethyl
acetate and evaporated under reduced pressure. The crude product
was purified by flash chromatography using cyclohexane/ethyl
acetate 70/30 as eluent.
Acknowledgements
This work was supported by the Fonds de la Recherche Scien-
tifiquedFNRS (F.R.S.-FNRS) and the Region Bruxelles-Capitale. R.R.
and J.M.-B. are Chercheurs qualifiés F.R.S.-FNRS and R.K. is a director
of research of the F.R.S.-FNRS.
4.1.10. Characterization of 21-methyl-8,17-dioxa-19,21-diazatricyclo
[16.2.1.02,7]henicosa-1(20),2,4,6,18-pentaene (1a). Colorless oil;
yield: 23.2 mg were obtained from 40 mg of 13a (19% over the two
Supplementary data
Full spectroscopic data, for all derivatives, are included as Sup-
plementary data. Supplementary data associated with this article
can be found in the online version, at doi:10.1016/j.tet.2010.04.070.
steps); Purity¼84%; 1H NMR (300 MHz, CDCl3):
¼7.33 (td, J¼8.2,
d
1.5 Hz, 1H), 7.25 (dd, J¼7.5, 1.5 Hz, 1H), 6.98 (dt, J¼7.4, 1.5 Hz, 1H),
6.94 (d, J¼8.2 Hz, 1H), 6.62 (s, 1H), 5.97e5.71 (m, 2H); 5.20e4.94
(m, 4H); 4.46 (t, J¼6.7 Hz, 2H), 3.97 (t, J¼6.6 Hz, 2H), 3.24 (s, 3H),
2.61e2.58 (m, 2H), 2.10e2.03 (m, 2H), 1.79e1.70 (m, 2H),
References and notes
1.52e1.42 ppm (m, 2H); 13C NMR (75 MHz, CDCl3):
d
¼156.9, 153.3,
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n
¼2927, 2854, 1715, 1531, 1452, 1269, 1248, 1165, 1072, 754 cmꢁ1
;

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