Substituted fused bicyclic pyrrolizinones as potent, orally bioavailable hNK1 antagonists

Article abstract of DOI:10.1016/j.bmcl.2010.01.065

Previous work on human NK₁ (hNK₁) antagonists in which the core of the structure is a 5,5-fused pyrrolizinone has been disclosed. The structural-activity-relationship studies on simple α- and β-substituted compounds of this series pr

Full text of DOI:10.1016/j.bmcl.2010.01.065

Bioorganic & Medicinal Chemistry Letters 20 (2010) 2007–2012
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Substituted fused bicyclic pyrrolizinones as potent, orally bioavailable
hNK1 antagonists
a
a
a
b
Gregori J. Morriello a, , Sander G. Mills , Tricia Johnson , Mikhail Reibarkh , Gary Chicchi ,
Julie DeMartino b, Marc Kurtz b, P. Davies b, K. L. C. Tsao b, Song Zheng c, Xinchun Tong c,
Emma Carlson d, Karen Townson d, F. D. Tattersall d, Alan Wheeldon d, Susan Boyce d, Neil Collinson d,
Nadia Rupniak d, Stephen Moore d, Robert J. DeVita a
*
a Department of Medicinal Chemistry, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA
b Department of Immunology, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA
c Department of Drug Metabolism, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA
d Department of Behavioral Neuroscience, Merck Research Laboratories, Terlings Park, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Previous work on human NK1 (hNK1) antagonists in which the core of the structure is a 5,5-fused pyrr-
Received 11 December 2009
Revised 14 January 2010
Accepted 14 January 2010
Available online 20 January 2010
olizinone has been disclosed. The structural–activity-relationship studies on simple a- and b-substituted
compounds of this series provided several potent and bioavailable hNK1 antagonists that displayed excel-
lent brain penetration as observed by their good efficacy in the gerbil foot-tapping (GFT) model assay.
Several of these compounds exhibited 100% inhibition of the foot-tapping response at 0.1 and 24 h with
ID50’s of less than 1 mpk. One particular a-substituted compound (2b) had an excellent pharmacokinetic
profile across preclinical species with reasonable in vivo functional activity and minimal ancillary
activity.
Keywords:
Neurokinin-1 antagonist
Nuerokinin receptor
Substance P
Ó 2010 Elsevier Ltd. All rights reserved.
In the 1990s several pharmaceutical companies embarked on
research to discover non-peptidic hNK1 antagonists as a possible
treatment for CNS disorders.1 Since then, extensive research has
produced many patents and publications, along with the first ap-
proved drug, EmendÒ, for treatment of chemo-induced emesis
and PONV.2,3 Considerable research on the physiological effects
of substance P (SP) on the NK1 receptor has led to other potential
medicinal uses for hNK1 antagonists including the treatment of
anxiety,4 depression,5 urge urinary incontinence,6 and possibly
alcoholism.7
Previously, we have disclosed the unsubstituted pyrrolizinone
(B), and shown that the compound had a superior brain penetra-
tion profile compared to several of the substituted pyrrolidine
compounds that preceded it.8 However, issues with hPXR and
CYP3A4 activity precluded any further studies with this com-
pound.8 Therefore, we chose to examine the effect on these off-tar-
get activities by the addition of small polar substituents to the
lactam ring. In this manuscript, we describe the SAR on this novel
substituted 5,5-fused pyrrolizinone design as potent hNK1 antago-
nists (see Fig. 1).
Synthesis of hydroxyl and amino substitutents on both the
- and b-position of the lactam ring proved to significantly
change the PK/PD profile of these compounds. Differences in
their ancillary activities were the main distinction between
the analogs.
a
a-Substituted analogs were directly synthesized from the 5,5-
fused pyrrolizinone 1 (Scheme 1). Oxidation of the enolate, formed
in situ with LHMDS, of lactam 1 with Vedejs’s reagent,9 MoOPh,
afforded a 1:1 mixture of hydroxyl substituted analogs 2a, 2b. This
mixture was then treated with mesylchloride in the presence of
triethylamine to give the intermediate mesylate. Displacement of
the mesyl moiety with sodium azide afforded the azido compound
which was reduced under Staudinger10 conditions to give the
primary amines 3a, 3b. To produce the geminal substituted com-
pounds, the hydroxyl intermediate 2a or 2b was oxidized to the ke-
tone 4 with the Dess–Martin reagent11 and treated with methyl
magnesium bromide to give the hydroxyl, methyl geminally
di-substituted pyrrolizinone 5a, 5b.
Scheme 2 describes the synthesis of the b-amino mono- and gem-
inally substituted analogs. We selected the (R)-2-hydroxymethyl
substituted pyrrolidine intermediate8 (6) as a suitable starting point
since it can be easily manipulated to other functional groups.
Oxidation to the aldehyde 7 was first performed to give an
intermediate viable for mono-b-substitutions. The aldehyde was
* Corresponding author. Tel.: +1 732 594 3867; fax: +1 732 594 5350.
E-mail address: greg_morriello@merck.com (G.J. Morriello).
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.01.065

2008
G. J. Morriello et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2007–2012
CF3
CF3
CF3
CF3
CF3
CF3
O
O
O
O
O
N
O
N
N
R1
R
F
R2
R
OH
F
F
B
A
R = H, CH3
C
NK1 IC50 = 0.06 nM
NK1 IC50 = 0.30 nM
with 50% HS IC50 = 43.1 nM
IP1 = 91% SPRR@100 nM
GFT:
Alpha or beta
with 50% HS IC50 = 2.2 nM
IP1 = 67% SPRR@100 nM
GFT:
0.1 h, 100%@1 mpk, ID50 = 0.03 mg/Kg
24 h, 100%@3mpk, ID50 = 0.30 mg/Kg
substitution
0.1 h, 49%@1 mpk
24 h,
0%@3mpk
Figure 1. Alpha- and/or beta-substituted compounds derived from bicyclic scaffold.
F3C
F3C
F3C
O
O
O
CF3
CF3
CF3
*
a
b
O
O
O
O
N
N
N
H
H
H
HO
F
F
F
4
1
2a,b
*Ref: BioOrg and Med. Chem. 2008, 16 (5), p. 2156-2170
f
c, d, e
F3C
F3C
O
O
CF3
CF3
O
O
N
N
HO
H
H
H2N
CH3
F
F
5a,b
3a,b
Scheme 1. Synthesis of the a-substituted analogs. Reagents and conditions: (a) MoOPh, LHMDS, THF, overnight, 0 °C to rt (1:1 mixture diastereomers, 78%); (b) 15% soln of
Dess–Martin reagent in DCM, rt, 3 h (89%); (c) mesylchloride, TEA, THF, rt, 5 h (82%); (d) NaN3, DMF, 60 °C, overnight (65%); (e) PPh3, THF/water, rt, overnight (88%); and (f)
1.0 M methylmagnesium bromide in THF, À20 °C (1:1 mixture diastereomers, 72%).
CF3
F3C
CF3
CF3
O
CF3
CF3
O
Boc
N
d
for 7: a
Boc
N
O
for 8: a, b, c
R
Boc
HO
N
N
S
O
F
F
R
O
9 R = H
10 R = CH3
F
6
7 R = H
8 R = CH3
e
F3C
F3C
F3C
O
CF3
O
CF3
HN
H2N
O
CF3
HN
O
S
g
f
O
N
R
R
N
H
F
H
F
R
O
NH2
F
O
OH
O
13a,b R = H
14,a,b R = CH3
11a,b R = H
12,a,b R = CH3
15a,b R = H
16,a,b R = CH3
Scheme 2. Synthesis of b-amino substituted analogs. Reagents and conditions: (a) 15% solnof Dess–Martin reagent in DCM, rt, 3 h; (b) 3.0 M soln of MeMgCl in THF, À78 °C to rt, 3 h;
(c) 15% soln of Dess–Martin reagent in DCM, rt, overnight; (d) R-(+)-2-methyl-2-sulfinimide, Titanium(IV) ethoxide, THF, reflux, overnight (71% over two steps); (e) tert-butyl acetate,
NaHMDS, ether, À78 °C, 3 h, (2:1 mixture diastereomers, 63%); (f) 4.0 N HCl in dioxane, 2 h, (quantitative); and (g) EDC, DMAP, DIEA, DCM overnight, rt (54%).

G. J. Morriello et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2007–2012
2009
then converted to the acetate 8 via methyl Grignard addition
followed by oxidation of the intermediate secondary alcohol to
the ketone via Dess Martin reagent. This sequence provides a sec-
ond intermediate for geminal b-substituted pyrrolizinones. Thus,
the Ellman12 sulfinimide 9 from the aldehyde 7 was prepared via
treatment with R-(+)-2-methyl-2-sulfinimide in the presence of a
dehydrating agent such as Ti(OEt)4. The sulfinimde 9 was then di-
rectly alkylated with the sodium anion of tert-butyl acetate,
F3C
CF3
O
CF3
CF3
Boc
HO
N
b, c
O
a
Boc
N
F
O
O
F
H
7
O
17a, b
F3C
F3C
F3C
O
O
O
CF3
CF3
CF3
d
O
O
O
e
N
N
N
H
OH
H
H
OH
H
H3C
O
F
F
F
18a, b
19
20a, b
Scheme 3. Synthesis of b-hydroxyl-substituted analogs. Reagents and conditions: (a) tert-butyl acetate, NaHMDS, ether, À78 °C, 3 h (3:1 mixture diastereomers, 77%); (b)
4.0 N HCl in dioxane, 2 h, (quantitative); (c) EDC, DMAP, DIEA, DCM overnight, rt (84%); (d) 15% soln of Dess–Martin reagent in DCM, rt, 3 h. (66%); and (e) 1.0 M
methylmagesium bromide in THF, À20 °C, (1:1 mixture diastereomers, 55%).
Table 1
a
-Substituted 5,5-fused pyrrolizinones15
CF3
CF3
O
O
N
R1
F
+50 %HS
R
Compound
R1
R
NK1
IP-lb
%
Gerbil FTc
Ion channelse
IC50 (nM)a
%Inhibition
Diltiazem sodium IC50 (nM)
2a
2b
3a
3b
5a
5b
OH
Fast isomer
Slow isomer
Fast isomer
Slow isomer
Fast isomer
Slow isomer
H
0.14
0.08
0.27
0.06
0.09
0.04
5.6
90
60
92
59
70
45
95c
8063
5138
4364
2822
239
H
0.91
100c
99c
9400
98
OH
NH2
NH2
OH
OH
H
2.1
H
0.38
2.5
100c
98c
214
CH3
CH3
1870
2177
4822
3198
0.80
100c
N
N
N
N
N
N
21a
21b
Fast isomer
Slow isomer
H
0.07
1.90
81
n/a
0d
>10,000
>10,000
5317
H
0.05
1.80
74
>10,000
Best set of compounds with substitutions shown below (better HS and IP-1 activity)
N
N
N
22
H
0.06
0.90
55
92c
598
1466
2412
N
H
N
N
NH
23
H
0.13
1.4
40
88d
301
N(CH3)2
Displacement of [125I] labeled substance P from the cloned hNKl receptor expressed in CHO cells. Data are mean (n = 3).
a
b
IP-l assay: it measures the response of inositol phosphate generation to substance P (10 lM) and is reported as the percent of substance P response remaining (SPRR) at
100 nM NK1 antagonist concentration.
c
Inhibition of GR73632 induced foot tapping in gerbils at 3 mg/kg iv at 24 h.
Inhibition of GR73632 induced foot tapping in gerbils at 1 mg/kg iv at 1 h.
Ion channels: binding assay in which IC50’s are calculated for both sodium and calcium (Dlz) channels.
d
e

2010
G. J. Morriello et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2007–2012
formed in situ by treatment with sodium hexamethyldisilazide, to
give 11a, 11b as a 2:1 mixture of diastereomers. Deprotection with
HCl followed by standard EDC coupling afforded the mono-amino
b-substituted compounds 15a and 15b. These were separated via
Gilson HPLC using a ChiralCel AD column eluting with 40% IPA in
heptane. The compounds were labeled ‘fast and slow eluting
isomers’ according to the order of separation since their absolute
stereochemical configurations remained unknown. The same pro-
cedures as described above were also used on the ketone derivative
8 to form the geminal amino, methyl b-substituted compounds
16a, 16b,13 with similar yields.
The related b-hydroxylated compounds were synthesized in a
similar manner, although, the aldehyde 7 was directly alkylated
with tert butyl acetate to afford 17a and 17b as a 3:1 mixture of
diastereomers (Scheme 3). Using the same procedures described
in the prior synthesis, the mono-b-hydroxyl substituted
compounds 18a and b were then prepared. To acquire the disubsti-
tuted analogs, intermediate 18a or b was oxidized via the Dess
Martin reagent to afford ketone 19 which was immediately treated
with methyl magnesium bromide to afford analogs 20a, and b. The
ketone 19 started to decompose upon sitting at room temperature
within minutes, therefore the treatment with Grignard reagent had
to be performed immediately.
Table 1 summarizes the biological results for the a-substituted
compounds. All of the compounds exhibit excellent in vitro binding
potency with subnanomolar binding affinities to the hNK1 recep-
tor. Their human serum shift affinities were variable but still show
low nanomolar activity.
Several compounds stood out due to their off target ion channel
selectivity which showed considerable variability. Comparing the
hydroxyl and amino compounds, it was apparent that the amino
substituent caused a significant increase in the sodium and cal-
cium channel binding, therefore, substantially decreasing their
off target selectivity. For example, the amino compounds 3a, 3b
exhibited a 40–100-fold increase in calcium channel binding along
with a 3–5-fold increase against the sodium channel versus the hy-
droxyl compounds 2a and 2b. In an attempt to counteract this
problem, basic heterocycles were introduced via reductive amina-
tion to the primary amine or direct formation onto the amine as in
compounds 21a and 21b. This modification improved the off target
selectivity, profoundly with compounds 21a and 21b, however, it
also resulted in the loss of brain penetrant properties as seen in
the gerbil foot-tapping16 (GFT) assay data. Compound 21a proved
to have no GFT response when dosed in the gerbils, while both
compounds 22 and 23 had decreased inhibition shown by their
inability to completely block the foot-tapping response. Several
other compounds were synthesized via reductive amination, how-
ever, compounds 22 and 23 were selected as representatives of the
series since they proved to have the best in vitro binding activity
along with adequate GFT foot-tapping inhibition.
Lastly, some other nitrogen analogs were obtained via the
amine substituted compounds 3, 15, and 16 by either reductive
amination with heterocycle containing aldehydes or formation of
the heterocycle 1,2,4-triazole via treatment with N,N-dimethylfo-
ramide azine in the presence of p-TSA refluxed in toluene over-
night.14 All compounds are shown in the two tables that follow.
Since the hydroxyl substituent proved to have superior off tar-
get ion selectivity versus the amine compounds with comparable
Table 2
b-Substituted 5,5-fused pyrrolizinones15
CF3
CF3
O
O
N
R
F
R2
Compound
R1
R
NK1
+50 %HS
IC50 (nM)a
IP-lb
%
Gerbil FTc
Ion channelse
%Inhibition
Diltiazem sodium IC50 (nM)
18a
18b
15a
15b
20a
20b
OH
Fast isomer
Slow isomer
Fast isomer
Slow isomer
Fast isomer
Slow isomer
H
0.08
0.07
0.09
0.08
0.07
0.06
2.10
65
79
75
87
28
57
100c
—
2376
1988
—
OH
H
2.70
0.60
0.77
1.10
2.60
—
NH2
NH2
OH
OH
H
100c
100c
96c
—
1877
1558
2209
—
7721
4983
2214
—
H
CH3
CH3
Only the better diastereomer shown below (with better HS and IP-1 activity)
NH2
N
16a
24
CH3
0.08
0.42
45
100c
767
1397
7822
N
N
H
0.07
0.83
52
od
>10,000
N
94c
2389
2966
N
25
H
0.13
1.83
68
N
H
a
Displacement of [125I] labeled substance P from the cloned hNKl receptor expressed in CHO cells. Data are mean (n = 3).
IP-l assay: it measures the response of inositol phosphate generation to substance P (10 lM) and is reported as the percent of substance P response remaining (SPRR) at
b
100 nM NK1 antagonist concentration.
c
Inhibition of GR73632 induced foot tapping in gerbils at 3 mg/kg iv at 24 h.
Inhibition of GR73632 induced foot tapping in gerbils at 1 mg/kg iv at 1 h.
Ion channels: binding assay in which IC50’s are calculated for both sodium and calcium (Dlz) channels.
d
e

G. J. Morriello et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2007–2012
2011
hNK1 binding affinity, analogs 5a and 5b were synthesized. These
were pursued in an effort to block possible metabolite issues, such
as oxidation to the ketone, which was seen with compound 2b.17
These analogs also had subnanomolar binding affinity, although
the ion channel selectivity was decreased. However, the com-
pounds were of sufficient interest to be profiled as potential
back-ups to compound 2b.
with an extremely low dose of compound needed for full inhibition
of the gerbil foot-tapping response, 0.02 mg/kg at 0.1 and 24 h,
respectively. Promising PK parameters were observed across spe-
cies with high bioavailability, >90%, and long half lives which
may be viable for once-daily dosing in man. Though, the major
concern was the long half life in dogs and rhesus which were over
days and not less than the preferred 24 h. Microsomal stability did
not account for these considerable long half lives especially with
rhesus showing the least stability with 23% parent remaining after
1 h. The ancillary activities were acceptable with greater than
Upon thorough analysis of the
a-substituted compounds, the
hNK1 antagonist 2b appeared to be superior, with subnanomolar
binding affinity with or without the presence of human serum
and greater than 1000-fold selectivity versus the ion channels. It
also exhibited 100% inhibition of the gerbil foot-tapping response
which was indicative of good brain penetration, therefore this
was one of the two compounds selected for further pharmacoki-
netic profiling. The second compound was selected from the
b-substituted hNK1 antagonists.
In the case of the b-substituted series of compounds, the ba-
sic amino substitution seemed to be more preferred versus the
hydroxyl substitution. The b-amino compounds had reduced hu-
man serum shifts and better sodium channel selectivity versus
the hydroxyl analogs. This only showed that similar substitu-
tions on different positions of the ring, even only one carbon
removed, can result in drastically different biological profiles
(see Table 2).
In this series of compounds, the differences in the intrinsic
activities between diastereomers were also minimal, all things
being equal when considering the assays standard deviation of
error. Intrinsic potency did not distinguish the two diastereomers
and therefore their human serum shift and off target activities
became the differentiating factors.
In examination of the b-hydroxyl substituted compounds,
18a, 18b, 20a, and 20b, it became clear that the human serum
shift values exhibited greater than 20-fold decrease in intrinsic
potency versus the activity seen without the presence of human
serum. Ion channel selectivity was reasonable with each having
60
l
M inhibition observed for 2D6, 2C9, and 3A4, and a moderate
M dose in hPXR was not of great
response of 31% inhibition at 10
l
concern. The gerbil PK/PD study exhibited an excellent ratio of
compound in brain versus plasma at 1 h indicating rapid brain pen-
etration (see Table 3).
Compound 15a had a comparable pharmacokinetic profile as
compared to compound 2b, although it is bioavailability was
somewhat lower, (78% versus 93%). hPXR activity was improved
with virtually no inhibition seen at 10 lM, and the human serum
shift was twofold less. However, titration of the gerbil foot-tapping
assay ascertained that approximately 40X the dose was necessary
for complete inhibition of the gerbil foot-tapping response versus
compound 2b. Thus, with this information, plus the observation
that compound 15a had reduced selectivity versus the ion chan-
nels when compared to 2b, it was decided to halt further evalua-
tion in favor of compound 2b (see Table 4).
A new series of
a- and b-substituted 5,5-fused pyrrolizinones
were prepared which exhibited sub-nanomolar hNK1 binding affin-
ity with good off-target selectivity. Many of these analogs had po-
tent in vivo activity in the gerbil foot-tapping model at 0.1 and 24 h
and demonstrated rapid brain penetration with long duration of
activity. Related work will be published in due course.20
2 lM binding in both the sodium and calcium channels. How-
Table 3
Profile of lead
a
-substituted hNK1 antagonist
ever, after direct comparison of these hydroxyl analogs with
amino compounds 15a and 15b, the human serum shift values
became the significant factor in deciding to abandon further bio-
logical studies on the hydroxyl analogs in favor of the amino
compounds.
In this series, the amino substituent seems to be more favored
with greater intrinsic potency for both isomers, 0.09 and
0.07 nM, respectively, with subnanomolar activity also in the pres-
ence of human serum. Complete inhibition of the foot-tapping re-
sponse in gerbils was observed in both diastereomers at 0.1 and
24 h points. The only difference seen was in ion channel selectivity
with isomer 1 having better selectivity versus both the sodium and
calcium channels. This slight differentiation was enough to select
compound 15a for further biological evaluation rather than 15b.
CF3
CF3
O
O
N
HO
H
F
2b19
IC50: 0.08 nM
IC50+50% human serum: 0.91 nM
IP-1: 60% SP remaining
Pharmacokinetics
Similar structural variations of the
a-substituted compounds
Rat
Dog
Rhesus
(i.e. 21a,b and 22) were synthesized in the b-amino series, as can
be seen with compounds 24 and 25, with analogous results. Espe-
cially troublesome was the decrease in inhibition of the GFT re-
sponse which led to the assumption that the analogs did not
penetrate the brain as well as the non-substituted primary amines.
The geminal substituted methyl, amino compounds (only dia-
stereomers 1 shown, 16a)18 were also prepared. Unfortunately,
off-target selectivity was greatly decreased as observed with the
Clp (ml/min/kg)
t1/2: (h)
Vd: (L/Kg)
F%:
5.1
13.0
4.2
0.8
128.2
2.8
1.0
80.4
2.6
93.0
98.0
68.0
Rat brain/plasma ratio: (1 mg/kg iv.): 1.0 (4 h)
GFT (iv):
ID50 = 0.02 mg/kg (1 h)
ID50 = 0.016 mg/kg (24 h)
Gerbil PK/PD iv study:
IC50 = 3.8 nM (1 h brain)
IC50 = 8.4 nM (1 h plasma)
Ancillary activity:
CYP inhibition
2D6:
3A4:
Microsomal stability:
% remaining (60 min)
Dog:
Human:
Rat:
calcium channel activity of 1.4
lM binding as compared to com-
pounds 15a and 15b with 7.7 and 4.9
l
M binding affinity, respec-
62.2
>100
>100
l
l
l
M
M
M
73
54
60
23
tively. Therefore, after examining the preliminary data on this
series of b-substituted hNK1 antagonists, compound 15a was se-
lected for further evaluation (see Table 2).
2C9:
Ion channels: 2.6–10
hPXR: 31% at 10
hLS180: 13-fold at 10
l
M
Rhesus:
lM
Evaluation of the properties of the
a-hydroxy substituted pyrr-
l
M (0.21 related rifamp.)
olizinone 2b demonstrated excellent brain penetrant properties

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Poli, S.; Vogel, C., et al J. Clin. Oncol. 2001, 19, 1759; (c) Kramer, M. S. et al Science
1998, 22, 1640.
Profile of lead b-substituted hNK1 antagonist
CF3
4. (a) Stahl, S. M. J. Clin. Psychiatry [Brainstorms] 1990, 60, 77; (b) Rupniak, N. M. J.;
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CF3
O
O
N
H
F
7. George, D. T.; Gilman, J.; Hersh, J.; Thorsell, A.; Herion, D.; Geyer, C.; Peng, X.;
Kielbasa, W.; Rawlings, R.; Brandt, J. E.; Gehlert, D. R.; Tauscher, J. T.; Hunt, S. P.;
Hommer, D.; Heilig, M. Science 2008, 14, 1536.
8. Morriello, G. J.; DeVita, R. J.; Mills, S. G.; Young, J. R.; Lin, P.; Doss, G.; Chicchi, G.
G.; DeMartino, J.; Kurzt, M. M.; Tsao, K.-L. C.; Carlson, E.; Townson, K.;
Wheeldon, A.; Boyce, S.; Collinson, N.; Rupniak, N.; Moore, S. Bio. Org. Med.
2008, 16, 2156.
NH2
15a
IC50: 0.10 nM
IC50+50% human serum: 0.6 nM
IP-1: 75% SP remaining
9. Vedejs, E.; Engler, D. A.; Telschow, J. E. J. Org. Chem. 1978, 24, 188.
10. (a) Staudinger, M. J. Helv. Chim. Acta. 1919, 2, 635; (b) Tian, W. Q.; Wang, Y. A. J.
Org. Chem. 2004, 69, 4299.
Pharmacokinetics
Rat
11. (a) Dess, D. B.; Martin, J. C. J. Org. Soc. 1983, 48, 4155; (b) Sato, Y.; Takimoto, M.;
Mori, m. Synlett 1997, 734.
12. (a) Liu, G.; Cogan, D. A.; Ellman, J. A. J. Am. Chem. Soc. 1997, 119, 9913; (b)
Brinner, K. M.; Ellman, J. A. Org. Biomol. Chem. 2005, 3, 2109.
13. Chiral separations were performed on either ChiralCel OD or ChiralPak AD
columns using eluants of either Heptane/IPA or Hexane/EtOH. Flow rate was
set at 9 mL and detection of the products was done using a Dio-Array UV
detector. Separations were determined via analytical HPLC and then carried
out on the preparative HPLC.
Clp (ml/min/kg)
t1/2: (h)
Vd: (L/Kg)
F%:
8.9
7.7
5.9
78.0
Rat brain/plasma ratio: (1 mg/kg iv.): 1.4 (4 h)
GFT (iv):
ID50 = 0.88 mg/kg (1 h)
ID50 = 0.92 mg/kg (24 h)
14. (a) Fohlisch, B.; Braun, R.; Schulze, K. W. Angew Chem., Int. Ed. Engl. 1967, 6,
361; (b) Bartlett, R. K.; Humphery, I. R. J. Chem. Soc. C 1967, 1664.
15. All compounds were characterized by 1H NMR and/or LC-MS. All assay data is
an average of two assays each measured in triplicate.
16. (a) Rupniak, N. M. J.; Williams, A. R. Eur. J. Pharmcol. 1994, 265, 179; (b)
Rupniac, N. M. J.; Tattersall, F. D.; Williams, A. R.; Rycroft, W.; Carlson, E. J.;
Cascieri, M. A.; Sadowski, S.; Ber, E.; Hale, J. J.; Mills, S. G.; MacCoss, M.; Seward,
E.; Huscroft, I.; Owen, S.; Swain, C. J.; Hill, R. G.; Hargreaves, R. J. Eur. J.
Pharmcol. 1997, 326, 201.
Ancillary activity
CYP inhibition
2D6:
3A4:
2C9:
66
>100
45 lM
l
M
lM
Ion channels: 1.2–9.1
hPXR: 0.9% at 10
lM
lM
Microsomal stability:
% remaining (60 min)
Dog:
Human:
Rat:
17. Unpublished metabolite profiling from rat PK data indicate that ketone 4 is
formed in vitro and in vivo from analog 2b.
89
66
85
91
18. In effort to conserve space in the table, the other diastereomer ,which would be
15b, was not included. The intrinsic binding for 15b was 0.11 nM and 1.8 nM in
the presence of 50% human serum, with ion channel affinity of 558 nM for
sodium and 1358 nM for the calcium channels. Functional IP-1 was 63% SP
remaining and GFT inhibition was mesured at 100% inh at 3 mpk iv at 24 h.
19. The relative stereochemistry of 2b was determined by use of 2D NOE NMR of
both diasteromers (2a and 2b). The most crucial evidence that determined the
sterochemistry of 2b was the presence of an NOE signal between the alpha
hydrogen adjancent to the hydroxyl substituent and the bridgehead hydrogen
of the fuse pyrrolidine ring. This would indicate that the hydroxyl group is in
the (S)-configuration. This NOE signal was also absent in its diastereomer, 2a.
20. Bao, J.; Lu, H.; Morriello, G. J.; Carlson, E. J.; Wheeldon, A.; Tschirret-Guth, R.;
Chicchi, G. G.; Kurtz, M. M.; Tsao, K.-L. C.; Zheng, S.; Tong, X.; Mills, S. G.;
DeVita, R. J. Bio. Org. Med., submitted for publication.
Rhesus:
Acknowledgments
The authors would like to thank Christopher Moyes and Paul
Finke for their help in the preparation of this manuscript. Their
assistance was greatly appreciated.
References and notes
1. (a) Satake, H.; Kawada, T. Curr. Drug Targets 2006, 7(8), 963; (b) Humphrey, J. M.
Curr. Top. Med. Chem. 2003, 3(12), 1423; (c) Quartara, L.; Altamura, M. Curr.
Drug Targets 2006, 7, 975.