Heteroarylureas with spirocyclic diamine cores as inhibitors of fatty acid amide hydrolase

Article abstract of DOI:10.1016/j.bmcl.2013.12.113

A series of mechanism based heteroaryl urea fatty acid amide hydrolase (FAAH) inhibitors with spirocyclic diamine cores is described. A potent member of this class, (37), was found to inhibit FAAH centrally, elevate the brain levels of three fatty acid ethanolamides [FAAs: anandamide (AEA), oleoyl ethanolamide (OEA) and palmitoyl ethanolamide (PEA)], and was moderately efficacious in a rat model of neuropathic pain.

Full text of DOI:10.1016/j.bmcl.2013.12.113

Bioorganic & Medicinal Chemistry Letters 24 (2014) 737–741
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Heteroarylureas with spirocyclic diamine cores as inhibitors of fatty
acid amide hydrolase
⇑
John M. Keith , William M. Jones, Joan M. Pierce, Mark Seierstad, James A. Palmer, Michael Webb,
Mark J. Karbarz, Brian P. Scott, Sandy J. Wilson, Lin Luo, Michelle L. Wennerholm, Leon Chang,
Sean M. Brown, Michele Rizzolio, Raymond Rynberg, Sandra R. Chaplan, J. Guy Breitenbucher
Janssen Research and Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of mechanism based heteroaryl urea fatty acid amide hydrolase (FAAH) inhibitors with spirocy-
clic diamine cores is described. A potent member of this class, (37), was found to inhibit FAAH centrally,
elevate the brain levels of three fatty acid ethanolamides [FAAs: anandamide (AEA), oleoyl ethanolamide
(OEA) and palmitoyl ethanolamide (PEA)], and was moderately efficacious in a rat model of neuropathic
pain.
Received 22 November 2013
Revised 23 December 2013
Accepted 27 December 2013
Available online 6 January 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
FAAH
Hydrolase
Covalent inhibitor
Spirocycles
The fatty acid amide hydrolases (FAAH and FAAH-2)1 are
responsible for the degradation of a variety of endogenous lipid
signaling molecules. FAAH preferentially degrades fatty acid ethan-
olamide substrates and FAAH-2 more readily breaks down primary
amides, though there is some substrate overlap between the two
enzymes. These hydrolases are differentially distributed with
FAAH being expressed primarily in the brain, liver, and white blood
cells while FAAH-2 is found in various peripheral tissues. The pre-
ferred substrates of FAAH include N-arachidonyl ethanolamide2
(AEA or anandamide), N-palmitoyl ethanolamide (PEA)3 and N-
oleoyl ethanolamide (OEA).4 AEA is the most rapidly degraded sub-
strate of the three and is an agonist of the cannabinoid receptor
CB1,5 which is likely the source of its analgesic pharmacology.
PEA is known to have anti-inflammatory properties and exert anal-
gesic effects through a non-cannabinoid pathway,3 while OEA ap-
pears to be involved in regulating satiety.6
FAAH enzyme, makes it a poor candidate as an analgesic. However,
inhibiting the FAAH enzyme should allow the potential pharmaco-
logical benefits of localized AEA elevation to be realized while
bypassing broad systemic increases that would result from
N
O
O
Me
N
H
N
N
H
N
N
N
N
S
S
N
Pfizer
JNJ-16610 10/Takeda
N
O
Cl
N
H
N
N
O
JNJ-40355003
Figure 1. Some known piperazinyl urea FAAH inhibitors.
Because AEA is synthesized and broken down in a highly local-
ized manner, side-effects associated with the dosing of exogenous
CB1 agonists (the so-called cannabinoid tetrad) are not observed.
When the mechanism of AEA breakdown is non-functioning, as
in FAAH(À/À) mice, administration of exogenous AEA led to a
side-effects profile similar to that of D8 THC;7 likely a result of
non-selective agonism of central CB1 receptors. AEA’s poor phar-
macokinetic properties and short half-life in the presence of the
N
O
O
O
N
N
H
N
N
H
N
N
Cl
F
O
O
N
Pfizer
Pfizer
CF3
O
N
H
N
O
F
O
Br
Amgen
⇑
Corresponding author.
E-mail address: jkeith@its.jnj.com (J.M. Keith).
Figure 2. Reported spirocyclic FAAH inhibitors.
0960-894X/$ - see front matter Ó 2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2013.12.113

738
J. M. Keith et al. / Bioorg. Med. Chem. Lett. 24 (2014) 737–741
levels in the plasma and brains8 of rats and the plasma of humans,
thus supporting the hypothesis that the pharmacology associated
with raised AEA levels should be in evidence upon administration
of a FAAH inhibitor.
n
n
Boc
Cl
N
HN
n
n
a, b
A
n
n
NH
N
O
n
n
We were interested in replacing the piperazinyl ring common
to a class of FAAH inhibitors reported by us and others9 (Fig. 1)
with a spirocyclic diamine template. Non-diamine spirocycles have
been prepared by others that act as mechanism based10 and com-
petitive11 inhibitors (Fig. 2). With this in mind, we prepared a ser-
ies of FAAH inhibitors bearing spirocyclic diamine cores. The
preparation of these compounds is described in Scheme 1. Most
of the desired spirocyclic diamines were available commercially
(mono-Boc or CBz protected) with the exception of 2,6-diazaspi-
ro[3.3]heptanes, which we prepared using the method developed
in Erick Carreira’s group.12
In order to efficiently screen spirocyclic cores, we elected to fix
the heteroaryl urea functionality as 3-pyridyl and the pendent ben-
zylic group as 3-(4-chlorophenoxy)benzyl, as both of these substit-
uents were well tolerated on a piperazine core (see JNJ-40355003,
Fig. 1 above). The results of the screen are shown in Table 1.
The initial screen revealed several interesting compounds with
reasonable potency at both the human and rat enzymes. We
decided to follow up on 3 spirocyclic cores in a total of 4-different
arrangements: 3,9-diazaspiro-[5.5]-undecane (5), 2,7-diazaspiro-
[3.5]-nonane (11 & 12) and 2,6-diazaspiro-[3.3]-heptane (13).
With these cores, we retained the 3-(4-chlorophenoxy)benzyl
group and varied the heteroaryl urea (Table 2). With each of the
O
O
n
c
HetAr
HetAr
Cl
N
H
N
N
H
OPh
n
n
N
n
d
e, a
O
n
HetAr
N
H
N
n
n
N
Boc
n
Scheme 1. Reagents and conditions: (a) spirocyclic diamine core (specifically
defined in Table 1) 1.1 equiv 3-(4-chlorophenoxy)benzaldehyde, 2.0 equiv
NaBH(OAc)3, 1.0 equiv Et3N (when amineÁHCl salt is used), THF, 0 °C to rt, 15–
24 h, 44–99%; (b) 5 equiv 4 N HCl/1,4-dioxane, DCM, rt, overnight, 79–99%; (c)
1.0 equiv heteroaryl phenyl carbamate (heteroaryl groups specifically defined in
Table 2), 2.0 equiv Et3N, DMSO, 55 °C, 15–24 h, 6–98%; (d) 2.0 equiv Et3N, 1.0 equiv
Boc(or CBz)-diamine, DMSO, 55 °C, 15–24 h, 17–100% (e) 5.0 equiv 4 N HCl/1,4-
dioxane, DCM, rt, 15–24 h, 99–100%.
administration of a CB1 agonist. Indeed, prior reports have robustly
demonstrated that inhibition of FAAH leads to an increase in AEA
Table 1
N
O
N
Cl
H
diamine
core
O
Compd
Diamine Core
hFAAH apparenta IC50s (nM)b
rFAAH apparenta IC50s (nM)b
493 153
N
N
1
93 36
N
N
2
3
1333 408
413 20
N
2600 1471
320 117
N
N
4
5
6
1300 141
27 1.2
710 166
287 57
N
N
N
N
>10,000
8667 1633
N
N
7
8
9
8667 1633
>10,000
1367 163
>10,000
N
N
N
N
N
>10,000
610 252
N
10
11
6333 2041
80 34
8000 1414
243 50
N
N
N
N
N
N
12
13
265 110
125 5c
148 66
N
1367 82
a
b
c
Values obtained after a 60 min preincubation with the enzyme.
Values are with n P 3 SEM.
N = 2.

Table 2
O
HetAr
N
H
Cl
diamine
core
O
Compd
HetAr group
Diamine Core
hFAAH apparenta IC50s (nM)b
rFAAH apparenta IC50s (nM)b
Compd
HetAr group
Diamine Core
hFAAH apparenta IC50s (nM)b
3250 750
rFAAH apparenta IC50s (nM)b
N
HN
N
N
N
N
N
N
N
N
N
N
14
15
26
47
50
4
4
6
38
9
27
28
56
6
H
N
N
N
N
N
N
N
N
N
N
N
86 13
260 109
151 68
N
N
N
N
N
N
N
N
16
17
18
30 10
29
30
31
6000 1414
5567 1559
38 12
O
Ph
N
N
N
N
N
N
N
N
N
N
123 15
31 10
5.3 1.1
23
7
N
N
N
N
Cl
N
N
30
5
247 94
225 125
N
N
N
N
N
N
N
19
20
21
43
3
133 29
38 13
22 1.8
32
33
34
275 75
173 53
127 28
333 163
535 85c
81 28
Cl
F
H
N
N
N
N
N
N
N
N
N
N
N
66 24
O
N
N
900 57
Me
N
O
N
N
N
N
N
N
N
N
N
N
N
N
N
22
23
24
177 47
300 57
333 11
20
28
7
8
35
36
37
38
553 92
393 22
235 29
CF3
N
N
N
16
9
5
0
CN
N
N
N
N
N
N
11 2.8
8
2
Cl
N
N
O
N
N
N
N
N
N
25
26
840 228
807 207
18 8c
42 12c
Cl
HN
N
5800 2581
1700 300
a
b
c
Values obtained after a 60 min preincubation with the enzyme.
Values are with n P 3 s.e.m.
N = 2.

740
J. M. Keith et al. / Bioorg. Med. Chem. Lett. 24 (2014) 737–741
Table 3
JNJ-42119779
Spinal Nerve Ligation
Mechanical Allodynia
Compd
Cl (L/kg/h)
Vss (L/kg)
T1/2 (h)
F (%)
JNJ-42119779 (p.o., 20 mg/kg, n=6)
Vehicle (p.o., water, 2 mL/kg, n=6)
JNJ-40355003 (p.o., 60 mg/kg, n=3)
11a
16a
18a
5b
10.4
2.55
1.0
21.8
11.3
2.21
18.0
1.68
3.35
1.81
5.69
32
62
71
69
100
75
50
25
0
p < 0.05 overall
2.26
PK data for selected compounds: male Sprague–Dawley rats 0.5 mg/kg iv, 2.0 mg/kg
p.o. (n = 3 each).
a
1:4:15 pharmasolve/cremaphore, D5W.
50% peg 400/water.
b
-25
1
2
3
4
Baseline
Post-treatment time (hrs)
Compound exposure of
Figure 5. Profile of JNJ-42119779 (37) in the spinal nerve ligation (Chung) model of
neuropathic pain.
JNJ-42119779 after oral dosing
(20 mg/kg in H2O, n=3)
3
Plasma
Brain
cores, we were able to prepare compounds with low double-digit
nM apparent IC50s for both h- and rFAAH, though large potency dif-
ferences between species was common.
2
Several compounds were profiled in standard iv & p.o. PK exper-
iments (Table 3). Two of the compounds, (16) and (18), possessed
reasonable PK parameters, but both also had a 6-(2H-1,2,3-triazol-
2-yl)pyridin-3-amino group as a component of the urea, which we
subsequently found to be mutagenic in the Ames II assay. This is a
concern as this functionality would be liberated in the course of
inhibiting FAAH. As a result of the mutagenicity data, compounds
(16) and (18) were not profiled further.
1
0
0
1
2
3
4
Time post-dose (hrs)
Figure 3. Brain and plasma exposures for JNJ-42119779 (37) after a 20 mg/kg oral
dose (vehicle = water).
As some of the compounds in Table 3 had very large volumes of
distribution, we elected to assess the ability of the potent analog
(37, JNJ-42119779) to cross the blood brain barrier (BBB) (Fig. 3),
inhibit FAAH centrally (Fig. 4), and increase the levels of the FAAs
AEA, OEA and PEA. From this experiment, we found that overall
exposure was low, but much higher in the brain than in the plas-
ma. Interestingly, there was less than 10% residual brain FAAH
activity between the 0.5 and 4 h time points post dosing, and the
levels of AEA, OEA and PEA were all greatly elevated at the 4 h time
point relative to the controls (AEA: 150%; PEA: 700%; OEA: 500%).
In sharp contrast, the potent bis-azatidine derivative (38) had very
low exposure, minimally inhibited brain FAAH and didn’t raise the
levels of AEA, PEA or OEA centrally.
Ex vivo brain FAAH activity
after oral dosing of JNJ-42119779
(20 mg/kg in H20, n=3)
125
100
75
50
25
0
The increases in FAA levels and the degree of central FAAH inhi-
bition observed with (37) encouraged us to profile the compound
in the spinal nerve ligation (Chung) model of neuropathic pain13
(Fig. 5). The compound was dosed at 20 mg/kg p.o. and compared
to a positive control, JNJ-40355003,14 a potent FAAH inhibitor.
From Figure 5, it is clear that (37) is not strongly efficacious at this
dose, but the effect does reach significance overall.
Figure 4. Ex vivo central FAAH activity after a 20 mg/kg oral dose of JNJ-42119779
(37).
125
100
75
50
25
0
Pre-dialysis
Post-dialysis at 4°C
Post-dialysis at room temperature
Figure 6. Percentage FAAH activity following overnight dialysis of JNJ-42119779 (37) at 4 °C & room temperature.

J. M. Keith et al. / Bioorg. Med. Chem. Lett. 24 (2014) 737–741
741
Johnson, D. S.; Stiff, C.; Lazerwith, S.; Kesten, S.; Fay, L.; Morris, M.; Beidler, D.;
Liimatta, M.; Smith, S.; Sadagopan, N.; Bhattachar, S.; Kesten, S.; Dudley, D.;
Nomanbhoy, T. K.; Cravatt, B. F.; Ahn, K. ACS Med. Chem. Lett. 2011, 2, 91; (d)
Ahn, K.; Smith, S. E.; Liimatta, M. B.; Beidler, D.; Sadagopan, N.; Dudley, D. T.;
Young, T.; Wren, P.; Zhang, Y.; Swaney, S.; Van Becelaere, K.; Blankman, J. L.;
Nomura, D. K.; Bhattachar, S. N.; Stiff, C.; Nomanbhoy, T. K.; Weerapana, E.;
Johnson, D. S.; Cravatt, B. F. J. Pharmacol. Exp. Ther. 2011, 338, 114; (e) Li, G. L.;
Winter, H.; Arends, R.; Jay, G. W.; Le, V.; Young, T.; Huggins, J. P. Br. J. Clin.
Pharmacol. 2012, 73, 706.
The reversibility of binding of compound (37) to the FAAH en-
zyme was tested via a dialysis experiment. The compound was
compared to the reversible binder OL-13515 and to the slow-off
substrate JNJ-1661010 (Fig. 6). The lack of return of enzymatic
activity after 24 h of dialysis suggest (37) is an irreversible binder
of the FAAH enzyme and is consistent with the findings for other
aryl ureas.16
9. (a) Johnson, D. S.; Ahn, K.; Kesten, S.; Lazerwith, S. E.; Song, Y.; Morris, M.; Fay,
L.; Gregory, T.; Stiff, C.; Dunbar, J. B.; Liimatta, M.; Beidler, D.; Smith, S.;
Nomanbhoy, T. K.; Cravatt, B. F. Bioorg. Med. Chem. Lett. 2009, 19, 2865; (b)
Keith, J. M.; Apodaca, R.; Tichenor, M.; Xiao, W.; Jones, W.; Pierce, J.; Seierstad,
M.; Palmer, J.; Webb, M.; Karbarz, M. J.; Scott, B.; Wilson, S.; Luo, L.;
Wennerholm, M.; Chang, L.; Brown, S.; Rizzolio, M.; Rynberg, R.; Chaplan, S.;
Breitenbucher, J. G. ACS Med. Chem. Lett. 2012, 3, 823–827.
10. (a) Meyers, M. J.; Long, S. A.; Pelc, M. J.; Wang, J. L.; Bowen, S. J.; Schweitzer, B.
A.; Wilcox, M. V.; McDonald, J.; Smith, S. E.; Foltin, S.; Rumsey, J.; Yang, Y.-S.;
Walker, M. C.; Kamtekar, S.; Beidler, D.; Thorarensen, A. Bioorg. Med. Chem. Lett.
2011, 21, 6545; (b) Meyers, M. J.; Long, S. A.; Pelc, M. J.; Wang, J. L.; Bowen, S. J.;
Walker, M. C.; Schweitzer, B. A.; Madsen, H. M.; Tenbrink, R. E.; McDonald, J.;
Smith, S. E.; Foltin, S.; Beidler, D.; Thorarensen, A. Bioorg. Med. Chem. Lett. 2011,
21, 6538.
In conclusion, we have discovered a series of spirocyclic hetero-
aryl ureas that demonstrate potent irreversible inhibition of the
FAAH enzyme. Despite strong engagement of the target in vivo,
only modest efficacy was observed in the spinal nerve ligation
model of neuropathic pain. The PK properties of these compounds
were found to be generally inferior to piperazinyl derivatives.
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