Design, synthesis, and structure - Activity relationship of tropane muscarinic acetylcholine receptor antagonists

Article abstract of DOI:10.1021/jm900736e

Novel tropane derivatives were characterized as muscarinic acetylcholine receptor antagonists (mAChRs). Through optimization of the structure - activity relationship around the tropane scaffold, the quaternary ammonium salt 34 was identified as a very pot

Full text of DOI:10.1021/jm900736e

J. Med. Chem. 2009, 52, 5241–5252 5241
DOI: 10.1021/jm900736e
Design, Synthesis, and Structure-Activity Relationship of Tropane Muscarinic Acetylcholine Receptor
Antagonists
ꢀ
Dramane I. Laine,* Zehong Wan, Hongxing Yan, Chongjie Zhu, Haibo Xie, Wei Fu, Jakob Busch-Petersen,
Christopher Neipp, Roderick Davis, Katherine L. Widdowson, Frank E. Blaney, James Foley, Alicia M. Bacon,
Edward F. Webb, Mark A. Luttmann, Miriam Burman, Henry M. Sarau, Michael Salmon, Michael R. Palovich, and
Kristen Belmonte
Respiratory CEDD, GlaxoSmithKline, 709 Swedeland Road, P.O. Box 1539, King of Prussia, Pennsylvania 19406-0939
Received May 18, 2009
Novel tropane derivatives were characterized as muscarinic acetylcholine receptor antagonists
(mAChRs). Through optimization of the structure-activity relationship around the tropane scaffold,
the quaternary ammonium salt 34 was identified as a very potent M3 mAChR antagonist. The
compound was functionally active and displayed greater than 24 h duration of action in a mouse
model of bronchoconstriction.
Introduction
nerves supplying the pulmonary smooth muscle, causing
increased acetylcholine release following vagal nerve stimula-
tion.10 This mAChR dysfunction results in airway hyperreac-
tivity and hyperresponsiveness mediated by increased
stimulation of M3 mAChRs. Thus, mAChR antagonists are
useful therapeutics in mAChR-mediated disease states and
particularly COPD. Inhaled anticholinergic agents approved
for the treatment of COPD include ipratropium bromide,
oxitropium bromide, and more recently tiotropium bro-
mide.11 Ipratropium and oxitropium have relatively short
durations of action (4-8 h), whereas tiotropium has a dura-
tion of action of over 24 h, making it suitable for once-daily
treatment.12 As part of a general strategy to develop new
respiratory products, our goal was to discover novel long-
acting muscarinic antagonists.
Muscarinic acetylcholine receptors (mAChRsa) belong to
the superfamily of G-protein-coupled seven-transmembrane
(TM) receptors. Five subtypes of mAChRs, termed M1-M5,
have been identified to-date.1,2 The mAChRs are widely
distributed in mammalian organs where they mediate many
of the vital functions.1-3 In the lungs, mAChRs have been
localized to smooth muscle in the trachea and bronchi, the
submucosal glands, and the parasympathetic ganglia.4 The
three subtypes of mAChRs that are known to exert their
physiological effect in the lungs through the action of the
native ligand, acetylcholine, are the M1, M2, and M3 recep-
tors.4 The M3 mAChRs are located on the airway smooth
muscle and also on the pulmonary submucosal glands where
they mediate muscle contraction and mucus secretion respec-
tively.5,6 The M2 mAChRs, which make up the majority of the
cholinergic receptor population on airway smooth muscle, are
also located on postganglionic parasympathetic nerves,7
where their role is autoinhibitory, to provide tightly regulated
control of acetylcholine release. M1 mAChRs are found in the
pulmonary parasympathetic ganglia where they function to
facilitate neurotransmission.8
The topography of the binding site of the muscarinic
receptors has been extensively studied over the years.13,14 In
particular, it has been established that two important struc-
tural features for an antimuscarinic agent are a positively
charged center (generally a protonated or quaternized
nitrogen) and an aromatic group attached to an ester moiety,
as exemplified by the belladonna alkaloids atropine and
scopolamine.15 The optimum distance between the nitrogen
and the carbonyl oxygen of 2,2-diphenylpropionate antimus-
mAChR dysfunction in the lungs has been noted in a
variety of different pathophysiological states.9 In particular,
in asthma and chronic obstructive pulmonary disease
(COPD), inflammatory conditions lead to loss of inhibitory
M2 mAChR autoreceptor function on parasympathetic
carinics has been estimated to be between 4.4 and 5.9 A.16 On
˚
the basis of that knowledge, we explored our compound
collection for molecules incorporating various nitrogen con-
taining rings (e.g., piperidine, pyrrolidine, or tropane) and an
aromatic moiety (e.g., phenyl, thiophene, or biphenyl) sepa-
rated by four to six carbon-carbon bonds. Through this
exercise, we uncovered the tropane derivative 1a, which had
been previously discovered by our predecessor Charles L.
Zirkle and his team during their research on antispasmotic
agents possessing parasympathetic activity.17 The general
strategytofurther explorethis template is depictedinFigure1.
From a pool of analogues of 1a, we gained useful information
on the attachment point stereochemistry and nature of the
linker. To further build upon this knowledge, our plan was to
*To whom correspondence should be addressed. Phone: 1-610-270-
7889. Fax: 1-610-270-4451. E-mail: dramane.i.laine@gsk.com.
a Abbreviations: mAChR, muscarinic acetycholine receptor; TM,
transmembrane; COPD, chronic obstructive pulmonary disease; SAR,
structure-activity relationship; HWE, Horner-Wadsworth-Emmons;
ACh, acetylcholine; CHO, Chinese hamster ovary; SPA, scintillation
proximity assay; MCh, metacholine; Penh, enhanced pause; i.n., intra-
nasal; HPLC, high pressure liquid chromatography; NQ, not quantifi-
able; ESI, electrospray ionization; HRMS, high resolution mass
spectrum; LC, liquid chromatography; FLIPR, fluorometric imaging
plate reader.
r
2009 American Chemical Society
Published on Web 07/24/2009
pubs.acs.org/jmc

5242 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16
Laineꢀ et al.
Figure 1. General strategy.
Table 1. Selection of Analogues of 1aa
% I b at 24 h
a
C-3 confi-
guration
M3 IC50
(nM)
a
compd
R
R1
Ph
linker
X
M3 pA2
(50 μg)
1a
1b
1c
1d
1e
1f
Ph
-CH2C(OH)
-CH2C(OH)
-C(OH)
-(CH2)2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CHdC
endo
exo
<10
8.6 ( 0.1
>10
Ph
Ph
Ph
Ph
2-Th
Ph
Ph
Ph
Ph
Ph
973 ( 110
1498 ( 140
134 ( 12
19 ( 4
endo
endo
endo
endo
endo
endo
endo
Ph
2-Pyr
2-Th
Et
<10
8.6 ( 0.1
>10
1g
1h
1i
135 ( 23
<10
<10
Ph
Ph
Br
Br
9.3 ( 0.2
8.3 ( 0.1
62
76
a Values are the mean of two or more independent assays. b % I = percent inhibition of MCh-induced bronchoconstriction in conscious mice.
further explore the substitution at the β-position of the side
chain and the structure-activity relationship (SAR) of the
aromatic region. In this paper, we report the key points of the
synthesis, structure-activity relationships, and pharmacolo-
gical evaluation of this series of mAChR antagonists.
treatment with a methylating agent to yield the alkenes 18, 19,
and 23.
Scheme 2 illustrates the synthetic approaches for the in-
stallation of various substituents at the β-position of the C-3
side chain. Iodination of the known primary alcohol 2424
followed by alkylation of the resultant iodide 25 with diphe-
nylacetonitrile in the presence of NaH provided the nitrile 26.
Further reduction of 26 with borane furnished the primary
amine 27, which was reacted with a variety of electrophiles
(isocyanates, acylating andsulfonaylatingagents) toprepare a
small array of ureas (28a-c), amide (28d), and sulfonamides
28e-f. Compound 26 could also be converted to the amide 29
upon treatment with sulfuric acid. The preparation of the
triphenyl derivative 30 proved more challenging. The best
method identified after exploring various conditions afforded
30 in about 17% yield by coupling 25 with triphenylmethane
inthe presence of n-BuLi. The carboxylic acid31was prepared
by treating 1a with formic acid and concentrated sulfuric acid
at -20 °C for 1 week.25 Subsequent coupling of 31 with
benzylamine afforded the amide 33, whereas microwave
assisted reduction of 32 with LiAlH4 gave the primary alcohol
32. Quaternization of the tertiary amines 26, 29, and 32 with
an appropriate methylating agent then afforded the corre-
sponding quaternary salts 34-36.
Chemistry
Thegeneralpreparationmethodsfor the alcohol andalkene
derivatives from Table 2 are depicted in Scheme 1. Tropinone
2a was converted to the corresponding R,β unsaturated ester
3avia a Horner-Wadsworth-Emmons (HWE) reaction with
trimethyl phosphonacetate.18-20 Catalytic hydrogenation of
3a gave the C-3 endo isomer 4a as the main product.19,21
Alternatively, the Knoevenagel condensation of 2a with ethyl
cyanoacetate gave an intermediate alkene,22 which was hy-
drogenated to afford the saturated nitrile derivative 3b.23 The
subsequent combined hydrolysis/decarboxylation of 3b fol-
lowed bytreatment withacidicethanol gavethe ester 4b.23 Ina
sequence similar to thatfor 2a, the HWE reaction of the [3.3.1]
bicyclic ketone 2b using diethyl (cyanomethyl)phosphonate
provided the alkane 3c, which was then hydrolyzed and
esterified in situ to give the ester 4c. Subsequent reaction of
4a, 4b, or 4c with an excess of an appropriate organometallic
reagent gave tertiary alcohol intermediates, which were sub-
sequently treated with a methylating agent to generate the
corresponding quaternary dimethyl ammonium salts 5-17
and 20-22. Alternatively, the tertiary alcohol intermediates
could undergo an acid catalyzed dehydration followed by
Pharmacology
The functional activities and potencies of the synthesized
compounds were first evaluated by calcium mobilization

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16 5243
Table 2. Structure-Activity Relationship Studies of Analogues of 1h
compd
n
R
linker
X
M3 IC50 a (nM)
M3 pA2
% I b at 24 h (5 μg)
1h
5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
Ph
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CHdC
Br
Br
Br
I
<10
9.3 ( 0.2
8.3 ( 0.2
34
2-Me-Ph
2-OMe-Ph
3-F-Ph
10 ( 5
>10000
11 ( 7
25 ( 8
>10000
74 ( 20
65 ( 57
37 ( 13
112 ( 74
290 ( 240
<10
6
7
8.0 ( 0.1
8
3-Cl-Ph
4-OMe-Ph
4-Cl-Ph
2-Me-3-F-Ph
2-Me-5-F-Ph
3,5-di-F-Ph
3,4-di-F-Ph
2-Th
I
9
Br
I
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Br
Br
Br
Br
Br
I
8.6 ( 0.1
19
3-Th
5-Me-3-Th
2-Th
17 ( 1
65 ( 36
<10
Br
Br
Br
I
10.0 ( 0.3
10.0 ( 0.4
8.7 ( 0.2
72
91
44
2-Me-Ph
2-Th
-CHdC
<10
<10
-CH2C(OH)
-CH2C(OH)
-CH2C(OH)
-CHdC
2-Me-Ph
Ph
2-Th
I
23 ( 2
<10
<10
Br
Br
8.8 ( 0.1
9.0 ( 0.1
34
49
a Values are the mean of two or more independent assays. b % I = percent inhibition of MCh-induced bronchoconstriction in conscious mice.
Scheme 1. General Methods of Preparation for the Compounds from Table 2a
a Reagents and conditions: (a) (MeO)2P(O)CH2CO2Me, NaH, THF, -45 °C to room temp, then reflux; (b) NCCH2CO2Et, NH4þAcO-, AcOH, H2,
Pd/C, EtOH (2a-3b); (c) (i) (MeO)2P(O)CH2CN, NaH, room temp, (ii) H2, AcCl, 10% Pd/C, MeOH (2b-3c); (d) H2, Pd/C, EtOH; (e) (i) conc HCl,
reflux; (ii) HCl, EtOH; (f) ArLi or ArMgX (see Table 2 for scope of Ar), THF or Et2O; (g) HCl or oxalic acid, reflux; (h) MeBr or MeI, acetone.
assays to determine inhibition of acetylcholine (ACh) induced
receptor activation at cloned human M3 receptors expressed
in CHO cells. The inhibitory potency of a compound was first
evaluated at a single ACh concentration to determine its IC50.
When a compound IC50 was lower than 10 nM, antagonist
potency was further quantified with a pA2, by measuring the
ratio of the EC50 of ACh in the presence and absence of the
compound.26 Antagonist binding was also assessed in radi-
oligand binding assays conducted using cell membrane pre-
parations from CHO cells expressing human M1, M2, or M3
receptors in a scintillation proximity assay (SPA) with 0.5 nM
[3H]-N-methylscopolamineasthe ligand. The bindingpotency
was determined as a Ki. Functional activity of antagonists was
determined in human bronchial tissues from primary, second-
ary, or tertiary airways obtained at autopsy, cut into strips,
then connected to force-displacement transducers suspended
in standard organ baths. Tissue strips were preincubated with
the test compound for 2 h and then incubated with increasing
concentrations of carbachol. The mechanical responses were
recorded isometrically, and the potencies of the compounds
were determined as pA2 values. To assess reversibility and to
calculate the off-rate, the antagonists were allowed to equili-
brate with the bronchial strips until they reached maximum
inhibition of carbachol-induced contraction. At this point
antagonists were removed from the perfusate and tissues were
superfused with buffer containing carbachol with tension
recovery measured over time. The results are expressed as
the time in minutes for 50% reversal of antagonist blockade of
carbachol-induced contraction (Off t50). The in vivo efficacy
of the compounds was determined by their blockade of airway

5244 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16
Scheme 2. Preparation of the Compounds from Table 3a
Laineꢀ et al.
a Reagents and conditions: (a) I2, PS-PPh3, DCM; (b) Ph2CHCN, NaH, DMF; (c) BH3.THF, THF; (d) addition of an electrophile such as (i)
PhCH2NCO, (ii) EtNCO, (iii) Ac2O, (iv) PhSO2Cl, or (v) MeSO2Cl; (e) H2SO4, DCM; (f) Ph3CH, n-BuLi; (g) HCO2H, H2SO4; (h) BnNH2, EDC, HOBt;
(i) LiAlH4, THF, microwave, 100 °C; (j) MeBr, t-BuOMe or MeI, acetone.
responsiveness to methacholine (MCh) induced contraction
in a mouse plethysmography model. Barometric plethysmo-
graphy was used to measure enhanced pause (Penh), a unitless
measure that has been shown to correlate with the changes in
airway resistance that occur during bronchial challenge with
methacholine.27 Mice were pretreated intranasally (i.n.) witha
solution of the compound in 50 μL of vehicle (10% DMSO)
and were then placed in the plethysmography chamber for a
given amount of time following drug administration. For
potency determination, a dose-response experiment was
performed, and all Penh measurements were carried out
15 min following i.n. drug administration. For duration of
action determination, repeated Penh measurements were
taken from 15 min up to 96 h following drug administration.
possessed either an alkyl or an alkylene linker. All these
compounds originated from the work of Zirkle et al.17 Sub-
sequently, the SAR of the compounds containing the alkane
linker was found to mirror very closely that of the alkenes and
therefore will not be reported in this article. From the
representative set shown in Table 1, it can be seen that the
endo configuration at C-3 is preferred as exemplified by the
marked decrease of potency at the M3 receptor of the exo
derivative 1b compared to its epimer 1a. The effect of the
length of the linker between the tropane ring and the diphenyl
moiety was assessed with compounds 1c and 1d. The sub-
stantial loss of affinities of these two molecules suggested that
a two-bond length linker, as in 1a, was probably optimal.
Replacement of one of the phenyl rings of 1a with a pyridine
ring as in 1e or with an ethyl chain as in 1g also resulted in a
loss of potency. However, the incorporation of thiophene
rings was tolerated and gave the equipotent analogue 1f,
which also exhibited a similar in vivo duration of action to
1a. Compound 1h, which is the dimethyl quaternary ammo-
nium derivative of 1a, displayed a slightly increased potency at
M3 but a significant longer duration of action than 1a.
A similar in vivo efficacy to 1h was found with compound
1i, which indicated that an ethylene group could be used as a
surrogate to the hydroxylethyl linker. This initial set of results
showed that the C-3 endo configuration, a quaternary ammo-
nium salt, and a two-carbon linker were all preferred features
around the tropane template.
Results and Discussion
The identification of 1a was a good starting point for our
program, as the compound exhibited a high intrinsic level of
potency at the M3 receptor. However, improvement was still
needed, as the compound did not exhibit significant bronch-
oprotection after 24 h in our in vivo mouse model at a
relatively high screening dose (50 μg/mouse) as shown in
Table 1. Further examination of our compound collection
uncovered a series of analogues of 1a possessing the same
hydroxyethyl group linking the tropane and the aro-
matic region. Other related compounds were also found that

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16 5245
Table 3. C-3 Side Chain β-Substitution
M3 IC50 (nM)a
M3 pA2
% I b at 24 h (5 μg)
a
compd
R2
X
1a
1h
-OH
-OH
-CN
<10
<10
8.6 ( 0.1
9.3 ( 0.2
9.5 ( 0.3
Br
34
11
26
<10
28a
28b
28c
28d
28e
29
-CH2NHC(O)NHBn
-CH2NHC(O)NHEt
-CH2NHC(O)CH3
-CH2NHS(O2)Ph
-CH2NHS(O2)CH3
-CONH2
-Ph
-CO2H
-CH2OH
-C(O)NHBn
-CN
1338 ( 320
1939 ( 410
2895 ( 1300
1059 ( 81
2732 ( 1100
<10
10.0 ( 0.1
8.4 ( 0.2
>10
15
30
31
206 ( 84
687 ( 250
<10
32
33
839 ( 450
<10
<10
34
35
Br
I
10.7 ( 0.2
9.9 ( 0.2
8.4 (n = 1)
>95
90
-CONH2
-CH2OH
36
Br
<10
23
a Unless specified, values are the mean of two or more independent assays. b % I = percent inhibition of MCh-induced bronchoconstriction in
conscious mice.
Taking these findings into consideration, SAR studies to
probe the aromatic region and the ring size were pursued by
preparing a series of quaternary ammonium salts derived from
1h. The compounds with an IC50 below 10 nM were screened in
our high-throughput mouse model at a fixed dose (5 μg/mouse)
to establish a SAR for duration of bronchoprotection. As
reported in Table 2, the 2-methyl analogue 5 showed high
affinity (10 nM) against the M3 receptor, whereas methoxy
substitution as in 6 resulted in a significant decrease in activity.
The introduction of a fluoro (7) or a chloro (8) at the meta
position was well tolerated. Para-substitution, however, was
detrimental for activity in the case of the chloro derivative 10
and led to a sharp drop in potency for the methoxy analogue 9.
The addition of a second substituent of small size on the
aromatic rings, such as a fluorine atom, was also detrimental
to activity (compare 11, 12 with 5 and 13, 14 with 7). As
previously observed with 1a and 1f, the -thiophene group was
a good bioisostere replacement for the phenyl, as compound
15 displayed an in vivo duration of action almost comparable
to 1h, albeit with a slightly lower potency at M3. Unlike the
2-thiophene derivatives, the 3-thiophenes 16 and 17 did not
meet our criteria for in vivo testing and were not further
investigated. The alkene derivatives 18 and 19 displayed great-
er potencies than the corresponding alcohols 15 and 5. More
interestingly, these compounds exhibited 72% and 91% in vivo
bronchoprotection after 24 h, respectively. The introduction of
an extra methylene into the bicyclic scaffold produced potent
compounds but did not bring any significant advantage over
the tropanes. For example, the [3.3.1] derivatives 21, 22, and 23
proved to be less potent at the M3 receptor and less efficacious
than compounds 5, 1h, and 18, respectively. However, the
duration of action of 20 was improved compared to 15 but far
shorter than that of 18 or 19.
important for potency and in vivo efficacy. On that basis, the
effect of substituting the linker at the C-20 position was
explored for further optimization.
As shown in Table 3, the nitrile 26 and the amide 29 were
more potent M3 antagonists than 1a, initially suggesting that
relatively small polar groups with hydrogen bond accepting
capabilities were preferred at the C-20 position. This assump-
tion was supported by the marked decrease in potency of the
phenyl 30, devoid of such potential. Carboxylic moieties,
however, were not preferred at this position as shown by
compound 31. The homoalcohol 32 was almost equipotent to
1a, suggesting that a moiety with more rotational freedom
could be tolerated. The R2 group could not, however, be too
large as it would clash with other residues in the receptor.
Thus, the clear drop in potency seen in 28a-e and 33
prompted us to stop any further investigation of this region
of our template. As was previously observed in the case of 1h
and related analogues, formation of the quaternary salts
derived from 26, 29, and 32 (34-36, respectively) led to some
significant improvement in the duration of action in our
screening model. This was particularly striking in the case of
34 and 35, which both exhibited near maximal protection of
bronchoconstriction at our screening dose (5 μg/mouse). The
lower efficacy in inhibiting bronchoconstriction of compound
36 correlated with its lower potency at the M3 receptor, when
compared with 34 and 35.
On the basis of the data reported above, compounds 18 and
34 were selected for further pharmacological evaluation
(Table 4). Radioligand binding studies showed that both
compounds potently competed with [3H]-N-methylscopola-
mine binding to any of the three mAChR subtypes (M1-M3).
At M3 mAChRs, 34 had an affinity about 8-fold higher than
18. No clear selectivity for M3 over the two other recep-
tors subtypes was observed. Compound 34 was also more
potent than 18 at endogenously expressed M3 mAChRs, as
The previous set of results indicated that the nature of the
linker between the tropane ring and the aromatic rings was

5246 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16
Table 4. Additional Data on Selected Compounds
Laineꢀ et al.
binding affinity (Ki)a
in vitro tissue studies
mouse in vivo studies
rat PK properties
off t50 (min)c ED50d (μg/mouse) duration (h)e Clf ((mL/min)/kg) oral F g (%)
b
compd
M1 (nM) M2 (nM) M3 (nM)
pA2
18
34
0.38 ( 0.07 0.73 ( 0.13 0.45 ( 0.04 9.0 ( 0.2 59 ( 9
0.05 ( 0.01 0.17 ( 0.01 0.06 ( 0.02 10.0 ( 0.2 85 ( 5
0.2
0.01
24 (5 μg)
>24 (0.5 μg) 74 ( 21
85 ( 7
6.5, 2.4, NQh,i
NQh
a Radioligand binding assays were conducted using CHO cell membrane preparations in SPA format vs 0.5 nM [3H]-N-methylscopolamine. Values
are the mean of two or more independent assays. b Potency against carbachol-induced contraction in human bronchus. c Reversal time for 50% of
carbachol-induced contraction to return to maximum relaxation in human bronchus after incubation at 10 nM antagonist. d Potency in conscious mice
against MCh-induced bronchoconstriction (n = 1). e Duration of bronchoprotection in conscious mice against MCh-induced bronchoconstriction.
Time to 50% loss of maximum protection (dose). f Cl: systemic plasma clearance. iv doses: 2.8 mg/kg (18), 2.5 mg/kg (34). g F: percent bioavailability. po
doses: 5.8 mg/kg (18), 5.7 mg/kg (34). h NQ: no quantifiable plasma levels following oral administration. i Individual doses listed because of variability.
than 18. Compared to 34, the in vivo potency of 18 was lower
and its duration of action was shorter. Taken together, these
results suggest that 34 has a better likelihood than 18 of
achieving long duration of bronchodilation in humans.
Further pharmacological studies of these compounds will be
reported elsewhere.
Experimental Section
Chemistry. All materials and reagents were used as is unless
otherwise indicated. Air- or moisture-sensitive reactions were
carried out under a nitrogen atmosphere. Flash chromatogra-
phy was performed using silica gel (EM Science, 230-400 mesh)
under standard techniques or using silica gel cartridges (RediSep
Figure 2. Duration of action-inhibition of MCh-induced bronch-
oconstriction in conscious mice. Balb/C mice (n = 4 for each) were
dosed with the test compound intranasally (i.n.) and then challenged
after 0.25-48 h with 30 mg/mL MCh aerosolized for 2 min. The
magnitude of bronchoconstriction was measured as Penh over the
next 5 min. The data are expressed as a ratio of the Penh achieved
with MCh after drug was given to that achieved before drug. A ratio
of 1.0 (dotted line) indicates that there was no change in the Penh in
response to aerosolized MCh (i.e., 0% inhibition), and a ratio of
0.0 means that there was no bronchoconstriction in response to
MCh challenge (i.e., 100% inhibition).
normal phase disposable flash columns) on an Isco Combi-
Flash. Preparative and analytical HPLC were carried out on a
Gilson 306 HPLC system. Unless otherwise stated, the condi-
tions for the preparative reverse phase HPLC purifications used
YMC Combiscreen ODS-A 75 mm ꢀ 30 mm (30 mL/min;
gradient, (A) acetonitrile, (B) water, 10-80% A during 10 min)
with UV detection at 214. The 1H NMR spectra were recorded
at 400 MHz using a Bruker Avance 400 spectrometer. Chemical
shifts are reported in parts per million (ppm) downfield of
tetramethylsilane (δ scale). Multiplicity is indicated as follows:
s (singlet), d (doublet), t (triplet), q (quartet), and m (multiplet).
Coupling constants (J) are reported in hertz and refer to
apparent multiplicities. Mass spectra were recorded on an
Applied Biosystems MDS Sciex API 150EX single quadrupole
mass spectrometer with an electrospray ionization (ESI) source.
Elemental analyses for compounds 18 and 34 were performed by
Quantitative Technologies, Inc., Whitehouse, NJ. High-resolu-
tion mass spectral (HRMS) data were determined on a Bruker
Daltonics 7T FTICR-MS, equipped with an Apollo ESI inter-
face. The purity of the tested compounds was determined by
liquid chromatography (LC) on a Schimadzu LC system. Unless
stated otherwise, the conditions for the LC used an Aquasil
C18 40 mm ꢀ 1 mm column (flow rate, 300 μL/min, 10%
solution A, 90% solution B; A = water with 0.02% TFA;
B = acetonitrile with 0.018% TFA, duration 4.2 min) with UV
detection at 214 nm. All reported compounds, with the excep-
tion of 5 and 13, possess a purity of at least 95%.
Methyl (8-Methyl-8-azabicyclo[3.2.1]oct-3-ylidene)acetate (3a).
Trimethylphosphonacetate (19.6 mL, 0.121 mol) was added
to a slurry of sodium hydride (95%, 3.15 g, 0.125 mol) in
THF (150 mL) at -45 °C. The resulting mixture was stirred
between -45 and -35 °C for 1 h. A solution of tropinone
(15 g, 0.108 mol) in THF (100 mL) was added, and the result-
ing mixture was stirred from -30 °C to room temperature over
2 h. The reaction mixture was then heated at reflux for 24 h.
After cooling to room temperature, the reaction mixture was
quenched with water (50 mL) and then concentrated under
vacuum to give a residue which was partitioned between 2 M
HCl (150 mL) and ether (400 mL). The aqueous phase was
separated, washed with ether (2 ꢀ 200 mL), then basified to pH
12 with 2.5 M NaOH (150 mL). The aqueous layer was then
extracted with ethyl acetate (4 ꢀ 100 mL). The combined
organics were dried over MgSO4 and concentrated to give
determined by tissue bath studies using human bronchus. In
additional kinetic studies, 34 was found to have an off rate of
85 min, which was longer than 18 (59 min).
The pharmacokinetic profiles of both compounds in the rat
were characterized by low oral bioavailability and high plas-
ma clearance (Table 4). These properties are preferred to
optimize the topical efficacy of these agents in the lungs28,29
and to minimize systemic exposure and thus potential
mAChR-mediated side effects. The compounds were also
further characterized in the mouse plesthymography model.
Compound 34 had excellent potency when dosed intranasally
with an ED50 of 0.01 μg. At a dose of 0.5 μg, 34 displayed
24-48 h of bronchoprotection (Figure 2). Elevation of the
dose to 5 μg showed greater than 48 h bronchoprotection,
indicating that the duration of action of 34 could be dose-
related. Compared to 34, the in vivo potency of 18 was lower
(ED50 = 0.2 μg/mouse) and its duration of action was shorter.
Taken together, these data suggest that the longer duration of
action of 34 than 18 may be a function of its higher potency
and lower reversibility at M3 mAChRs.
Conclusion
In conclusion, a novel series of tropane derivatives was
characterized as mAChR antagonists. Through optimization
of the structure-activity relationship around the tropane
scaffold, compounds 18 and 34 were identified as very potent
M3 mAChR antagonists. Kinetic washout studies in human
bronchus showed that 34 had a slower reversibility profile

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16 5247
methyl (8-methyl-8-azabicyclo[3.2.1]oct-3-ylidene)acetate as a
crude oil (16 g, 76%). LC/MS (ES) m/z 196 (M þ H)þ. 1H
NMR (400 MHz, CDCl3) δ ppm 5.71 (t, J = 2.15 Hz, 1 H), 3.70
(s, 3 H), 3.52 (d, J = 15.16 Hz, 1 H), 3.27 (br s, 2 H), 2.71 (d, J =
13.64 Hz, 1 H), 2.43 (d, J = 15.41 Hz, 1 H), 2.39 (s, 3 H), 2.08-
1.91 (m, 3 H), 1.52 (dd, J = 8.08, 1.52 Hz, 2 H).
Methyl (3-endo)-(8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]ace-
tate (4a). A sample of 10% Pd/C (1 g) was added to a solution
of crude 3a (16 g) in MeOH (400 mL). The resulting mixture was
allowed to hydrogenate at room temperature under a 40-56 psi
pressure of H2. After 43 h no H2 intake was observed. After
filtration of the catalyst over Celite, the solvent was evaporated
under vacuum to give a crude oil which was purified by distilla-
tion to give a colorless oil (11.2 g, 69%), bp 122-125 °C (0.3
mmHg). 1H NMR (400 MHz, CDCl3) δ ppm 3.68 (s, 3 H), 3.15-
3.08 (m, 2 H), 2.49 (d, J = 8.34 Hz, 2 H), 2.27 (s, 3 H), 2.30-2.25
(m, 1 H), 2.17 (ddd, J = 18.19, 4.29, 4.04 Hz, 2 H), 2.07 (dd, J =
8.34, 3.79 Hz, 2 H), 1.63 (d, J = 8.34 Hz, 2 H), 1.30 (d, J = 14.91
Hz, 2 H).
Ethyl Cyano[(3-endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]ace-
tate (3b). A mixture of tropinone (13.9 g, 0.1 mol), ethyl cyanoa-
cetate (11.3 g, 0.1 mol), ammonium acetate (1.6 g, 0.021 mol),
acetic acid (7.3 g, 0.12 mol), and 10% Pd/C (0.6 g) in absolute
ethanol (20 mL) was hydrogenated under 60 psi at 50 °C for 18 h.
After the catalyst was filtered off, the filtrate was evaporated
under vacuum. The amber oily residue was dissolved in 1 N HCl
(200 mL), and the solution was extracted with ether (200 mL).
The acid solution was neutralized and saturated with K2CO3. The
product was extracted with ether (6 ꢀ 200 mL). Distillation of the
ether solution gave 3b as a yellow oil (8.0 g, 34%), bp 139-140 °C
(2 mmHg). 1H NMR (400 MHz, CDCl3) δ ppm 4.28 (q, J = 7.20
Hz, 2 H), 3.55 (d, J = 9.6 Hz, 1 H), 3.23-3.15 (m, 2 H), 2.52-2.42
(m, 1 H), 2.35-2.12 (m, 4 H), 2.24 (s, 3 H), 1.60-1.40 (m, 3 H),
1.30-1.20 (m, 1 H), 1.33 (t, J = 7.20 Hz, 3 H).
concentrated under reduced pressure. S sample of 10% Pd-C
(266 mg, 0.25 mmol) and then MeOH (10 mL) were added, and
the mixture was stirred at room temperature under an atmo-
sphere of hydrogen for 22 h. The reaction mixture was filtered
through Celite 521, and the filtrate was concentrated under
reduced pressure. The residue was taken up in saturated K2CO3
(10 mL) and EtOAc (10 mL). The layers were separated, and the
aqueous layer was extracted with EtOAc (3ꢀ10 mL). The com-
bined organic layers were dried (Na2SO4) and concentrated
under reduced pressure. The crude product was purified by
flash chromatography, giving 517 mg (58%) of [(3-endo)-9-
methyl-9-azabicyclo[3.3.1]non-3-yl]acetonitrile. LC/MS (ES)
1
m/z 179 (M)þ. H NMR (400 MHz, CDCl3) δ ppm 3.03 (d,
J = 10.9 Hz, 2 H), 2.51 (s, 3 H), 2.31-2.18 (m, 5 H), 2.00-1.84
(m, 3 H), 1.49-1.46 (m, 1 H), 1.27-1.21 (m, 2 H), 0.98 (d,
J = 12.1 Hz, 2 H).
Ethyl [(3-endo)-9-Methyl-9-azabicyclo[3.3.1]non-3-yl]acetate
(4c). A solution of [(3-endo)-9-methyl-9-azabicyclo[3.3.1]non-
3-yl]acetonitrile (515 mg, 2.89 mmol) in concentrated HCl (10
mL) was heated at reflux for 2 h and then concentrated under
reduced pressure. In a separate flask, a solution of 2 M HCl/
EtOH (5 mL) was prepared by dropwise addition of acetyl
chloride (0.7 mL, 9.8 mmol) to EtOH (4.3 mL) with stirring
(caution: exothermic). This solution was then added to the crude
product previously obtained, and the mixture was stirred at
room temperature for 24 h and then concentrated under reduced
pressure. The residue was taken up in a 2:1 mixture of saturated
K2CO3/EtOAc (15 mL). The layers were separated, and the
aqueous layer was extracted with EtOAc (3 ꢀ 5 mL). The
combined organic layers were dried (Na2SO4) and concentrated
under reduced pressure, giving 516 mg (79%) of the title
compound. LC/MS (ES) m/z 226.2 (M)þ. 1H NMR (400
MHz, CDCl3) δ ppm 4.13 (m, 2 H), 3.00 (d, J = 9.9 Hz, 2 H),
2.51 (s, 3 H), 2.40-2.33 (m, 1 H), 2.24-2.12 (m, 4 H), 1.98-1.84
(m, 3 H), 1.46-1.42 (m, 1 H), 1.29-1.24 (m, 3 H), 1.14-1.07 (m,
2 H), 0.95 (d, J = 10.9 Hz, 2 H).
Method A: Preparation of the Tertiary Alcohol Derivatives 5-
15 and 17. To a solution of an organometallic reagent (6-8
equiv) in ether or THF at 0 °C, methyl (3-endo)-(8-methyl-8-
azabicyclo[3.2.1]oct-3-yl]acetate (1 equiv) in anhydrous THF
(4 mL/mmol) was added dropwise. After warming up to room
temperature and stirring at room temperature for half an hour,
the reaction mixture was heated at reflux for 2 h. The reaction
mixture was quenched with aqueous saturated ammonium
chloride and then extracted with ethyl acetate. The organic
phase was concentrated and purified by reverse-phase HPLC
to afford the tertiary alcohol intermediate, which was redis-
solved in acetone and treated with bromomethane or iodo-
methane (20 equiv) at room temperature. The resulting
solution was stirred at room temperature for 12 h. The reaction
mixture was filtered off and washed with cold ether to give the
quaternary salts as solids.
Method B: Preparation of the Alkenes Derivatives 18 and 19.
To a solution of an organometallic reagent (6-8 equiv) in ether
or THF at 0 °C, methyl (3-endo)-(8-methyl-8-azabicyclo-
[3.2.1]oct-3-yl]acetate (1 equiv) in anhydrous THF (4 mL/mmol)
was added dropwise. After warming to room temperature and
being stirred at room temperature for half an hour, the reaction
mixture was heated at reflux for 2 h. The reaction mixture was
quenched with aqueous saturated ammonium chloride and then
extracted with ethyl acetate. The organic phase was concen-
trated and purified by reverse-phase HPLC to afford the tertiary
alcohol intermediate, which was redissolved in 6 N HCl (5 mL/
mmol) or 2 M aqueous oxalic acid (5 equiv). The mixture was
heated at reflux for 1 h, then cooled down and rendered alkaline
by addition of 10% NaOH. The aqueous mixture was extracted
three times with ether. After evaporation of the ether, a residue
was obtained, which was redissolved in acetone and treated with
bromomethane or iodomethane (20 equiv) at room tempera-
ture. The resulting solution was stirred at room temperature for
(3-endo)-(8-Methyl-8-azabicyclo[3.2.1]oct-3-yl)acetic Acid Eth-
yl Ester (4b). A solution of 3b (5.6 g) in 37% hydrochloric acid (25
mL) was heated at reflux for 13 h. The solution was evaporated
under vacuum. The residual water was removed with successive
addition and removal by distillation of absolute ethanol. The
crude was treated with a solution of absolute ethanol (40 mL)
saturated with hydrogen chloride and allowed to stand overnight
at room temperature. Most of the alcohol was removed under
vacuum. Then a cold 5 N NaOH solution (20 mL) was added to
the residue and the product was extracted with ether (6 ꢀ 50 mL).
Removal of ether gave the desired product as a pale-yellow oil
1
(5.0 g, 100%). H NMR (400 MHz, CDCl3) δ ppm 4.12 (q,
J=7.20 Hz, 2 H), 3.09 (br s, 2 H), 2.46-2.42 (m, 1 H), 2.45 (d,
J = 8.40 Hz, 2 H), 2.24 (s, 3 H), 2.15-2.10 (m, 2 H), 2.07-
2.02 (m, 2 H), 1.64 (m, 2 H), 1.31-1.21 (m, 2 H), 1.24 (t, J = 7.20
Hz, 3 H).
[(3-endo)-9-Methyl-9-azabicyclo[3.3.1]non-3-yl]acetonitrile (3c).
Step 1. Diethyl (cyanomethyl)phosphonate (5.12 mL, 31.7 mmol)
was added dropwise over 6 min to a stirred slurry of 95% NaH
(800 mg, 31.7 mmol) in anhydrous THF (32 mL) under argon at
room temperature. This mixture was stirred for 40 min, and a
solution of 9-methyl-9-azabicyclo[3.3.1]nonan-3-one (970 mg,
6.33 mmol) in THF (10 mL) was added in one portion. Stirring
was continued for 70 h, whereupon MeOH (5 mL) was added in
one portion. The mixture was concentrated under reduced pres-
sure, and the residue was taken up in a 1:1 mixture of H2O/EtOAc
(20 mL). The layers were separated, and the aqueous layer was
extracted with EtOAc (4 ꢀ 5 mL). The combined organic layers
were dried (Na2SO4) and concentrated under reduced pressure.
The crude product was purified by flash chromatography,
giving 886 mg (79%) of (9-methyl-9-azabicyclo[3.3.1]non-3-ylide-
ne)ethanenitrile as a yellow oil. LC/MS (ES) m/z 177 (M)þ.
Step 2. Acetyl chloride (0.57 mL, 7.49 mmol) was added
dropwise with stirring to MeOH (3.2 mL) at room tempera-
ture. (9-Methyl-9-azabicyclo[3.3.1]non-3-ylidene)ethanenitrile
(880 mg, 4.99 mmol) was dissolved in this solution and then

5248 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16
Laineꢀ et al.
12 h. The reaction mixture was filtered off and washed with cold
ether to give the quaternary salts as solids.
compound was prepared by method A in 9.6% yield. LC/MS
(ES) m/z 400 (M)þ. Purity by LC: 100%. 1H NMR (400 MHz,
MeOD-d4) δ ppm 7.64 (dd, J = 11.39 Hz, J = 2.74 Hz, 2 H),
7.08-7.03 (m, 2 H), 6.95-6.89 (m, 2 H), 3.72 (br s, 2 H), 3.07 (s, 3
H), 3.05 (s, 3 H), 2.79 (d, J = 6.11 Hz, 2 H), 2.55-2.30 (m, 6 H),
2.22-2.10 (m, 1 H), 1.83 (s, 6 H), 1.70-1.63 (m, 2 H). HRMS
calcd for (C25H32F2NOþ) 400.2447, found 400.2443.
(3-endo)-3-[2-Hydroxy-2,2-bis(2-methylphenyl)ethyl]-8,8-di-
methyl-8-azoniabicyclo[3.2.1]octane Bromide (5). The title com-
pound was prepared by method A in 38% yield. LC/MS (ES) m/
z 364 (M)þ. Purity by LC: 86%. 1H NMR (400 MHz, MeOD-d4)
δ ppm 7.81 (d, J = 7.83 Hz, 2 H), 7.26-7.19 (m, 2 H), 7.16 (t, J
= 7.45 Hz, 2 H), 7.03 (d, J = 7.33 Hz, 2 H), 4.87 (s, 1 H), 3.72 (br
s, 2 H), 3.07 (s, 3 H), 3.05 (s, 3 H), 2.85 (d, J = 5.81 Hz, 2 H),
2.51-2.39 (m, 2 H), 2.38-2.14 (m, 5 H), 1.85 (s, 6 H), 1.60 (d, J
= 15.66 Hz, 2 H). HRMS calcd for (C25H34N2Oþ) 364.2635,
found 364.2635.
(3-endo)-3-{2-Hydroxy-2,2-bis[2-(methyloxy)phenyl]ethyl}-
8,8-dimethyl-8-azoniabicyclo[3.2.1]octane Bromide (6). The title
compound was prepared by method A in 10% yield. LC/MS
(ES) m/z 396(M)þ. Purity by LC: 100%. 1H NMR (400 MHz,
DMSO-d6) δ ppm 7.52 (dd, J = 7.83, 1.77 Hz, 2 H), 7.20 (s, 1 H),
7.20 (dd, J = 15.41, 1.52 Hz, 1 H), 6.95 (t, J = 7.58 Hz, 2 H),
6.89 (d, J = 8.08 Hz, 2 H), 5.20 (s, 1 H), 3.72-3.65 (m, 2 H), 3.48
(s, 6 H), 2.95 (s, 3 H), 2.93 (s, 3 H), 2.80 (d, J = 6.06 Hz, 2 H),
(3-endo)-3-[2,2-Bis(3,5-difluorophenyl)-2-hydroxyethyl]-8,8-
dimethyl-8-azoniabicyclo[3.2.1]octane Bromide (13). The title
compound was prepared by method A in 10% yield. LC/MS
1
(ES) m/z 408 (M)þ. Purity by LC: 93%. H NMR (400 MHz,
MeOD-d4) δ ppm 7.20-7.11 (m, 4 H), 6.89-6.82 (m, 2 H), 3.77
(br s, 2 H), 3.09 (s, 3 H), 3.07 (s, 3 H), 2.78-2.70 (m, 2 H), 2.65-
2.40 (m, 6 H), 2.15-2.01 (m, 1 H), 1.87 (d, J = 16.39 Hz, 2 H).
HRMS calcd for (C23H26F4NOþ) 408.1945, found 408.1944.
(3-endo)-1,1-Bis(3,4-difluorophenyl)-2-(8,8-dimethyl-8-azoniabi-
cyclo[3.2.1]oct-3-yl)ethanol Bromide (14). The title compound was
prepared by method A in 38% yield. LC/MS (ES) m/z 408 (Mþ).
1
Purity by LC: 100%. H NMR (400 MHz, MeOD-d4) δ ppm
7.45-7.39 (m, 2 H), 7.30-7.19 (m, 4 H), 3.76 (br s, 2 H), 3.08 (s, 3
H), 3.06 (s, 3 H), 2.74 (d, J = 6.14 Hz, 2 H), 2.50-2.35 (m, 6 H),
2.15-2.02 (m, 1 H), 1.83 (d, J = 16.44 Hz, 2 H). HRMS calcd for
(C23H26F4NOþ) 408.1945, found 408.1944.
2.35-2.28 (m, 2 H), 2.21-2.09 (m, 4 H), 1.96-1.84 (m, 1 H),
þ
1.58 (d, J = 15.92 Hz, 2 H). HRMS calcd for (C25H34NO3
396.2533, found 396.2530.
)
(3-endo)-1,1-Bis-(3-fluorophenyl)-2-(8,8-dimethyl-8-azoniabi-
cyclo[3.2.1]oct-3-yl)ethanol Iodide (7). The title compound was
prepared by method A in 10% yield. LC/MS (ES) m/z 372 (M)þ .
LC/MS (ES) m/z 372 (Mþ). Purity by LC: 100%. 1H NMR (400
MHz, MeOD-d4) δ ppm 7.36 (m, 2 H), 7.26 (m, 4 H), 6.96 (m, 2
H), 3.74 (br. s, 2 H), 3.07 (s, 3 H), 3.03 (s, 3 H), 2.77 (d, J = 6.00
Hz, 2 H), 2.47-2.40 (m, 6 H), 2.12 (br s, 1 H), 1.89 (d, J = 14.8
Hz, 2 H). HRMS calcd for (C23H28F2NOþ) 372.2134, found
372.2131.
(3-endo)-3-[2,2-Bis(3-chlorophenyl)-2-hydroxyethyl]-8,8-di-
methyl-8-azoniabicyclo[3.2.1]octane Iodide (8). The title com-
pound was prepared by method A in 10% yield. LC/MS (ES) m/
z 404 (M)þ. Purity by LC: 100%. 1H NMR (400 MHz, DMSO-
d6) δ ppm 7.56 (d, J = 1.60 Hz, 2 H), 7.46 (d, J = 8.00 Hz, 2 H),
7.34 (d, J = 7.60 Hz, 2 H), 7.27 (d, J = 7.20 Hz, 2 H), 3.74 (br,
2 H), 2.99 (s, 3 H), 2.93 (s, 3 H), 2.73 (d, J = 5.60 Hz, 2 H), 2.32-
2.18 (m, 6 H), 1.89 (br s, 1 H), 1.76 (d, J = 4.80 Hz, 2 H), 1.71 (s,
1 H). HRMS calcd for (C23H28Cl2NOþ) 404.1543, found
404.1541.
(3-endo)-3-{2-Hydroxy-2,2-bis[4-(methyloxy)phenyl]ethyl}-
8,8-dimethyl-8-azoniabicyclo[3.2.1]octane Iodide (9). The title
compound was prepared by method A in 10% yield. LC/MS
(ES) m/z 396 (M)þ. Purity by LC: 100%. 1H NMR (400 MHz,
DMSO-d6) δ ppm 7.33 (d, J = 9.09 Hz, 4 H), 6.83 (d, J = 14.91
Hz, 4 H), 5.42 (s, 1 H), 3.71 (s, 6 H), 3.73-3.67 (m, 2 H), 2.96 (s, 3
H), 2.93 (s, 3 H), 2.61 (d, J = 6.06 Hz, 2 H), 2.35-2.13 (m, 6 H),
1.95-1.88 (m, 1 H), 1.72 (d, J = 15.66 Hz, 2 H). HRMS calcd
for (C25H34NO3þ) 396.2533, found 396.2530.
(3-endo)-3-(2-Hydroxy-2,2-di-2-thienylethyl)-8,8-dimethyl-
8-azoniabicyclo[3.2.1]octane Iodide (15). The title compound
was prepared by method A in 61% yield. LC/MS (ES) m/z 348
(Mþ). Purity by LC: 100%. 1H NMR (400 MHz, DMSO-d6) δ
ppm 7.38 (dd, J = 5.05, 1.26 Hz, 2 H), 7.05 (dd, J = 3.54, 1.26
Hz, 2 H), 6.96 (dd, J = 5.05, 3.79 Hz, 2 H), 6.39 (s, 1 H), 3.72 (br
s, 2 H), 2.99 (s, 3 H), 2.94 (s, 3 H), 2.68 (d, J = 6.06 Hz, 2 H),
2.12-2.37 (m, 6 H), 1.96-2.11 (m, 1 H), 1.67 (d, J = 15.92 Hz, 2
H). HRMS calcd for (C19H26NOS2þ) 348.1450, found 348.1447.
(3-endo)-1,1-Bis-(3-thienyl)-2-(8,8-dimethyl-8-azoniabicyclo-
[3.2.1]oct-3-yl)ethanol Iodide (16). A solution of 3-bromothio-
phene (1.93 g, 11.8 mmol) in ether (6 mL) was cooled to -70 °C
and added with stirring to a solution of n-butyllithium (2.5 M in
hexane, 4.8 mL) at -70 °C under Ar. The reaction mixture was
stirred at -70 °C for 30 min. (3-endo)-(8-Methyl-8-azabicyclo-
[3.2.1]oct-3-yl)acetic acid ethyl ester (1.00 g, 4.74 mmol) in ether
was added via cannula, and the solution was kept stirring at
-70 °C for 1 h. Water (10 mL) was added and the reaction
mixture allowed warmed to room temperature. The reaction
mixture was then extracted with ether and washed with satu-
rated NaCl. The ether layer was dried over Na2SO4 and evapo-
rated to give a crude product, which was purified by reverse-
phase HPLC to afford (3-endo)-1,1-bis-(3-thienyl)-2-(8-methyl-
8-azabicyclo[3.2.1]oct-3-yl)ethanol as white solid (460 mg,
29%). LC/MS (ES) m/z 334 (M þ H)þ. A solution of (3-endo)-
1,1-bis-(3-thienyl)-2-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)etha-
nol (100 mg, 0.30 mmol) in dichloromethane/acetonitrile
(2:1,12 mL) was mixed with iodomethane (852 mg, 6 mmol) at
room temperature. The resulting mixture was stirred at room
temperature for 12 h. The reaction mixture was concentrated to
afford the title compound as a white solid (130 mg, 91%). LC/
(3-endo)-1,1-Bis-(4-chlorophenyl)-2-(8,8-dimethyl-8-azoniabi-
cyclo[3.2.1]oct-3-yl)ethanol Iodide (10). The title compound was
prepared by method A in 10% yield. LC/MS (ES) m/z 404 (M)þ.
1
MS (ES) m/z 348 (M)þ. Purity by LC: 100%. H NMR (400
1
Purity by LC: 100%. H NMR (400 MHz, MeOD-d4) δ ppm
MHz, MeOD-d4) δ ppm 7.39-7.32 (m, 4 H), 7.06 (dd, J = 5.20,
1.40 Hz, 2 H), 3.75 (br s, 2 H), 3.09 (s, 3 H), 3.06 (s, 3 H), 2.68 (d,
7.46 (d, J = 13.60 Hz, 4 H), 7.34 (d, J = 14.00 Hz, 4 H), 3.74 (br
s, 2 H), 3.07 (s, 3 H), 3.05 (s, 3 H), 2.75 (d, J = 13.60 Hz, 2 H),
2.47-2.34 (m, 6 H), 2.08 (br s, 1 H), 1.85(d, J = 15.66 Hz, 2 H).
HRMS calcd for (C23H28Cl2NOþ) 404.1543, found 404.1542.
(3-endo)-1,1-Bis(3-fluoro-2-methylphenyl)-2-(8,8-dimethyl-8-
azoniabicyclo[3.2.1]oct-3-yl)ethanol Bromide (11). The title com-
pound was prepared by method A in 10% yield. LC/MS (ES) m/
z 400 (Mþ). Purity by LC: 100%. 1H NMR (400 MHz, MeOD-
d4) δ ppm 7.64 (d, J = 7.93 Hz, 2 H), 7.29-7.22 (m, 2 H), 7.00 (t,
J = 8.92 Hz, 2 H), 3.72 (br s, 2 H), 3.07 (s, 3 H), 3.05 (s, 3 H), 2.83
(d, J = 6.04 Hz, 2 H), 2.51-2.25 (m, 6 H), 2.20-2.00 (m, 1 H),
1.80 (s, 6 H), 1.63 (d, J = 16.03 Hz, 2 H). HRMS calcd for
(C25H32F2NOþ) 400.2447, found 400.2448.
J = 6.40 Hz, 2 H), 2.50-2.31 (m, 6 H), 2.22-2.12 (m, 1 H), 1.82
þ
(d, J = 16.00 Hz, 2 H). HRMS calcd for (C19H26NOS2
348.1450, found 348.1448.
)
(3-endo)-3-[2-Hydroxy-2,2-bis(4-methyl-3-thienyl)ethyl]-8,8-
dimethyl-8-azoniabicyclo[3.2.1]octane Bromide (17). The title
compound was prepared by method A in 12% yield. LC/MS
1
(ES) m/z 376 (M)þ. Purity by LC: 100%. H NMR (400 MHz,
DMSO-d6) δppm 7.53 (s, 2 H), 7.03 (s, 2 H), 5.33 (s, 1H), 3.70 (br s,
2 H), 2.99 (s, 3 H), 2.94 (s, 3 H), 2.66-2.62 (m, 2 H), 2.35-2.15 (m,
6 H), 2.15-2.00 (m, 1 H), 1.70 (s, 6 H), 1.46 (d, J = 15.75 Hz, 2 H).
HRMS calcd for (C21H30NO S2þ) 376.1763, found 376.1761.
(3-endo)-3-(2,2-Di-2-thienylethenyl)-8,8-dimethyl-8-azoniabi-
cyclo[3.2.1]octane Bromide (18). The title compound was
(3-endo)-1,1-Bis(5-fluoro-2-methylphenyl)-2-(8,8-dimethyl-8-
azoniabicyclo[3.2.1]oct-3-yl)ethanol Bromide (12). The title

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16 5249
prepared by method B in 79%. LC/MS (ES) m/z 346 (M)þ. Purity
by LC: 100%. 1H NMR (400 MHz, DMSO-d6) δ ppm 6.73 (dd,
J = 5.18, 1.14 Hz, 1 H), 6.51 (dd, J = 5.05, 1.01 Hz, 1 H), 6.33
(dd, J = 5.05, 3.54 Hz, 1 H), 6.25 (dd, J = 3.41, 1.14 Hz, 1 H),
6.17 (dd, J = 5.18, 3.66 Hz, 1 H), 6.09 (dd, J = 3.54, 1.26 Hz, 1
H), 5.83 (d, J = 9.85 Hz, 1 H), 3.07 (br s, 2 H), 2.35 (s, 3 H), 2.31
(s, 3 H), 2.31-2.23 (m, 1 H), 1.87-1.68 (m, 4 H), 1.60-1.52 (m,
2 H), 1.11 (d, J = 16.17 Hz, 2 H). Anal. (C19H24NS2Br) C, H, N.
(3-endo)-3-[2,2-Bis(2-methylphenyl)ethenyl]-8,8-dimethyl-8-
azoniabicyclo[3.2.1]octane Bromide (19). The title compound
was prepared by method B in 19% yield. LC/MS (ES) m/z 346
(M)þ.)þ. Purity by LC: 100%. 1H NMR (400 MHz, MeOD-d4) δ
ppm 7.30-7.05 (m, 8 H), 6.23 (d, J = 10.51 Hz, 1 H), 3.87 (br s,
2 H), 3.12 (s, 3 H), 3.11 (s, 3 H), 2.95-2.82 (m, 1 H), 2.75-2.55
(m, 4 H), 2.40-2.30 (m, 2 H), 2.34 (s, 3 H), 2.08 (s, 3 H), 1.89 (d,
J = 16.14 Hz, 2 H). HRMS calcd for (C25H32Nþ) 346.2527,
found 346.2529.
(3-endo)-3-(2-Hydroxy-2,2-di-2-thienylethyl)-9,9-dimethyl-9-
azoniabicyclo[3.3.1]nonane Iodide (20). Step 1. A solution of ethyl
[(3-endo)-9-methyl-9-azabicyclo[3.3.1]non-3-yl]acetate (4c) (273
mg, 1.21 mmol) in THF (3 mL) was added dropwise to a 1 M
solution of 2-thienyllithiuminTHF (4.8 mL, 4.8 mmol) at-30 °C
under argon. The cooling bath was removed, and stirring was
continued for another 5 h, whereupon H2O (3 mL) was added.
The layers were separated, and the aqueous layer was extracted
with EtOAc (3 ꢀ 2 mL). The combined organic layers were
combined and washed with saturated NaCl, then dried (Na2SO4)
and concentrated under reduced pressure. The crude product was
purified by flash chromatography on silica gel (20 g), eluting with
5% MeOH/CH2Cl2 (600 mL) followed by 10% MeOH/CH2Cl2
(300 mL) to give 145 mg (48%) of 2-[(3-endo)-9-methyl-9-
azabicyclo[3.3.1]non-3-yl]-1,1-di-2-thienylethanol. LC/MS (ES)
m/z 226 (M)þ.
(3-endo)-3-(2-Hydroxy-2,2-diphenylethyl)-9,9-dimethyl-9-azo-
niabicyclo[3.3.1]nonane Bromide (22). Step 1. A solution of ethyl
[(3-endo)-9-methyl-9-azabicyclo[3.3.1]non-3-yl]acetate (315 mg,
1.40 mmol) in THF (7 mL) was added to a 1.5 M solution of PhLi
in 70:30 cyclohexane/Et2O (3.73 mL, 5.6 mmol) at -30 °C (bath
temp) under argon. The ice bath was removed, and the mixture
was stirred for 3 h, whereupon H2O (5 mL) was added, followed
by EtOAc (5 mL). The layers were separated, and the aqueous
layer was extracted with EtOAc (4 ꢀ 2 mL). The combined
organic layers were washed with saturated NaCl (1 ꢀ 5 mL),
dried (Na2SO4), and concentrated under reduced pressure. The
crude product was purified on a Biotage 25þS cartridge (20 g
silica gel) at 5 psi, eluting with 0.5% aqueous NH4OH/10%
MeOH/CH2Cl2 (2 L) to give 295 mg (63%) of 2-[(3-endo)-
9-methyl-9-azabicyclo[3.3.1]non-3-yl]-1,1-diphenylethanol. LC/
MS (ES) m/z 336.2 (M)þ.
Step 2. A 2 M solution of MeBr in tert-butyl methyl ether
(1.19 mL, 2.38 mmol) was added to a solution of 2-[(3-endo)-9-
methyl-9-azabicyclo[3.3.1]non-3-yl]-1,1-diphenylethanol (40 mg,
0.119 mmol) in acetone (1 mL). The mixture was stirred at room
temperature for 43 h. The precipitate was filtered off, rinsed with
Et2O (1 mL), and dried under high vacuum to give 43.5 mg
(85%) of title compound. LC/MS (ES) m/z 350 (M)þ. Purity by
1
LC: 100%. H NMR (400 MHz, DMSO-d6) δ ppm 7.48 (d,
J = 7.33 Hz, 4 H), 7.29 (t, J = 7.58 Hz, 4 H), 7.17 (t, J = 7.20
Hz, 2 H), 5.59 (s, 1 H), 3.42 (br s, 2 H), 3.08 (s, 3 H), 2.95 (s,
3 H), 2.63 (d, J = 5.05 Hz, 2 H), 2.41-2.32 (m, 2 H), 2.25-
2.18 (m, 2 H), 2.12-2.02 (m, 1 H), 1.96-1.84 (m, 1 H), 1.60-
1.54 (m, 5 H). HRMS calcd for (C24H32NOþ) 350.2478, found
350.2477.
(3-endo)-3-(2,2-Di-2-thienylethenyl)-9,9-dimethyl-9-azoniabi-
cyclo[3.3.1]nonane Bromide (23). A solution of ethyl [(3-endo)-9-
methyl-9-azabicyclo[3.3.1]non-3-yl]acetate (200 mg, 0.888
mmol) in THF (4.4 mL) was added to a solution of 1 M 2-
thienyllithium (3.55 mL, 3.55 mmol) at -30 °C (bath temp). The
ice bath was removed, and the mixture was stirred at room
temperature for 3 h. Water (5 mL) and EtOAc (5 mL) were
added, the layers were separated, and the aqueous layer was
extracted with EtOAc (4 ꢀ 2 mL). The combined organic layers
were washed with saturated NaCl (1 ꢀ 5 mL), dried (Na2SO4),
and concentrated under reduced pressure. The crude product
was purifiedby flash chromatographyon silica gel, giving 305mg
(99%) of the title compound 2-(9-methyl-9-azabicyclo-
[3.3.1]non-3-yl)-1,1-di-2-thienylethanol.
Step 2. To a suspension of the compound previously prepared
(200 mg, 0.58 mmol) in water (2 mL) was added oxalic acid (207
mg, 2.3 mmol) in vial, which was sealed. The mixture was heated
at 110 °C for 1 h. Then a solution of 6 M NaOH (1 mL) was
added, and the mixture was extracted with EtOAc (4 ꢀ 2 mL).
The combined organic layers were dried (Na2SO4) and concen-
trated under reduced pressure. The crude product was purified
by flash chromatography on silica gel, giving 135 mg (71%) of
3-(2,2-di-2-thienylethenyl)-9-methyl-9-azabicyclo[3.3.1]nonane.
Step 3. To a solution of the compound previously prepared
(74 mg, 0.225 mmol) in acetone (1 mL) was added methyl
bromide (2.25 mL, 4.5 mmol). The reaction mixture was stirred
at room temperature for 80 h. The resulting precipitate was
filtered and washed with Et2O (3 ꢀ 1 mL). The filter cake was
dried under high vacuum, giving 61 mg (64%) of the title
compound. LC/MS (ES) m/z 344 (M)þ. Purity by LC: 100%.
1H NMR (400 MHz, MeOD-d4) δ ppm 7.54 (d, J = 5.05 Hz, 1
H), 7.31 (d, J = 5.05 Hz, 1 H), 7.15-7.12 (m, 1 H), 7.09-7.06
(m, 1 H), 6.96 (t, J = 3.54 Hz, 1 H), 6.89-6.86 (m, 1 H), 6.46 (d,
J = 8.59 Hz, 1 H), 3.55 (br s, 2 H), 3.26-3.15 (m, 1 H), 3.23 (s, 3
H), 3.12 (s, 3H), 2.76-2.68 (m, 2 H), 2.47-2.35 (m, 2 H), 2.20-
2.06 (m, 1 H), 1.87-1.74 (m, 5 H). HRMS calcd for
(C20H26NS2þ) 344.15012, found 344.14982.
Step 2. MeI (0.034 mL, 0.547 mmol) was added to a solution
of 2-[(3-endo)-9-methyl-9-azabicyclo[3.3.1]non-3-yl]-1,1-di-2-thi-
enylethanol (19 mg, 0.0547 mmol) in acetone (1 mL). The mixture
was stirred at room temperature for 20 h, and the solvent was
removed under reduced pressure to give a crude product, which
was rinsed with Et2O (5 ꢀ 1 mL). The washings were filtered, and
the combined solid residue was dried under high vacuum to give
the title compound (17 mg, 88%). LC/MS (ES) m/z 362.2 (M)þ.
1
Purity by LC: 100%. H NMR (400 MHz, DMSO-d6) δ ppm
7.39-7.37 (m, 2 H), 7.05-7.04 (m, 2 H), 6.99-6.95 (m, 2 H), 6.37
(s, 1 H), 3.44 (m, 2 H), 3.09 (s, 3 H), 2.98 (s, 3 H), 2.61 (d, J = 5.05
Hz, 2 H), 2.44-2.39 (m, 2 H), 2.27-2.13 (m, 3 H), 1.91-1.77 (m,
1 H), 1.64-1.54 (d, J = 15.92 Hz, 5 H).
(3-endo)-3-[2-Hydroxy-2,2-bis(2-methylphenyl)ethyl]-9,9-di-
methyl-9-azoniabicyclo[3.3.1]nonane Iodide (21). Step 1. To a
solution of ethyl [(3-endo)-9-methyl-9-azabicyclo[3.3.1]non-3-
yl]acetate (4c) (300 mg,1.33 mmol) in THF (15 mL) was added
a 2 M solution of 2-methylphenylmagnesium bromide in THF
(4 mL, 7.9646 mmol). The reaction mixture was heated at 70 °C
for 2 h. Water (5 mL) was added to quench the reaction. The
reaction mixture was extracted with ethyl acetate (3 ꢀ 10 mL),
dried (MgSO4), and concentrated. The tertiary amine inter-
mediate (130 mg, 27%) was obtained after purification with
CombiFlash, eluting with 9:1 MeOH/CH2Cl2. LC/MS (ES) m/z
364.8 (M)þ.
Step 2. To a solution of 2-[(3-endo)-9-methyl-9-azabicyclo-
[3.3.1]non-3-yl)-1,1-bis(2-methylphenyl)ethanol (25 mg, 0.068
mmol) in acetone (5 mL) was added methyl iodide (0.5 mL, 8.03
mmol). The reaction mixture was stirred overnight. The title
compound (20 mg, 77%) was obtained after concentration. LC/
MS (ES) m/z 378.4 (Mþ). Purity by LC: 100%. 1H NMR (400
MHz, MeOD-d4) δ ppm 7.86 (d, J = 7.60 Hz, 2 H), 7.24 (t, J =
7.20 Hz, 2 H), 7.18 (d, J = 7.20 Hz, 2 H), 7.04 (d, J = 7.20 Hz,
2 H), 3.17 (s, 3 H), 3.06 (s, 3 H), 2.76 (d, J = 4.80 Hz, 2 H), 2.56
(s, 1 H), 2.45-2.36 (m, 5 H), 2.32 (s, 1 H), 2.07 (br s, 1 H), 1.85 (s,
6 H), 1.70-1.68 (m, 4 H), 1.53-1.51 (m, 2 H). HRMS calcd for
(C26H36NOþ) 378.2791, found 378.2790.
(3-endo)-3-Iodomethyl-8-methyl-8-azabicyclo[3.2.1]octane
(25). A solution of iodine (6.67 g, 25.8 mmol) and ((endo)-8-
methyl-8-azabicyclo[3.2.1]oct-3-yl)methanol (2.0 g, 12.9 mmol)

5250 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16
Laineꢀ et al.
in CH2Cl2 (120 mL) was mixed with PS-PPh3 (8.6 g, 3 mmol/g,
25.8 mmol). The resultant mixture was stirred for 17 h, filtered,
and concentrated to afford the title compound (2.63 g, 77%).
LC/MS (ES) m/z 266 (M þ H)þ. 1H NMR (CDCl3) δ ppm 3.81
(s, 2H), 3.45 (d, 2H), 2.98 (m, 2H), 2.79 (d, 3H), 2.39 (m, 3H),
2.05 (m, 4H).
3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphe-
nylpropanenitrile Trifluoroacetate (26). A solution of (3-endo)-
iodomethyl-8-methyl-8-azabicyclo[3.2.1]octane (1.06 g, 4.0 mmol)
and Ph2CHCN (2.32 g, 12.0 mmol) in DMF (20 mL) was mixed
with NaH (0.288 g, 12.0 mmol). The resultant mixture was stirred
at room temperature for 60 min. Filtration and purification by
reverse phase HPLC then afforded the title compound (1.16 g,
93%). LC/MS (ES) m/z 331 (M þ H)þ. Purity by LC: 100%. 1H
NMR (400 MHz, CDCl3) δ ppm 7.43-7.30 (m, 10 H), 3.83 (br s, 2
H), 2.82-2.66 (m, 5 H), 2.59-2.40 (m, 2 H), 2.38-2.05 (m, 5 H),
1.78 (d, J = 15.66 Hz, 2 H).
N-{3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-di-
phenylpropyl}benzenesulfonamide Trifluoroacetate (28d). A so-
lution of 3-[(3-endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,
2-diphenylpropylamine (67.0 mg, 0.20 mmol) in CH2Cl2 (2.0
mL) was mixed with PhSO2Cl (28.2 μL, 0.22 mmol) and Et3N
(84.3 μL, 0.60 mmol). The result mixture was stirred at room
temperature for 1 h and concentrated. Purification of the residue
by reverse phase HPLC then afforded the title compound (51.5
mg, 54%) as a TFA salt. LC/MS (ES) m/z 475 (M þ H)þ. Purity
by LC: 100%. 1H NMR (400 MHz, MeOD-d4) δ ppm 7.80 (d,
J = 8.34 Hz, 2 H), 7.67-7.60 (m, 1 H), 7.55 (t, J = 7.58 Hz, 2 H),
7.29 (t, J = 7.20 Hz, 4 H), 7.23 (d, J = 7.07 Hz, 2 H), 7.12 (d, J =
8.08 Hz, 4 H), 3.69 (br s, 2 H), 3.61 (s, 2 H), 2.69 (s, 5H), 2.30 (br s,
4 H), 2.05 (s, 1 H), 2.03-1.95 (m, 2 H), 1.94-1.87 (m, 1 H),
1.39 (d, J = 15.41 Hz, 2 H). HRMS calcd for (C29H34N2O2Sþ)
475.2414, found 475.2415.
N-{3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-di-
phenylpropyl}methanesulfonamide Trifluoroacetate (28e). The
title compound was prepared from 3-[(3-endo)-8-methyl-8-aza-
bicyclo[3.2.1]oct-3-yl]-2,2-diphenylpropylamine and MeSO2Cl
by following the procedure for compound 28e (28% yield).
LC/MS (ES) m/z 413 (M þ H)þ. Purity by LC: 100%. 1H NMR
(400 MHz, MeOD-d4) δ ppm 7.34 (br s, 4 H), 7.21-7.28 (m, 6 H),
3.84 (br s, 2 H), 3.68 (br s, 2 H), 2.76 (s, 3 H), 2.68 (br s, 5 H),
2.30 (br s, 4 H), 2.05-1.84 (m, 3 H), 1.39 (d, J = 14.40 Hz, 2 H).
3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphe-
nylpropanamide Trifluoroacetate (29). A solution of 3-[(3-endo)-
8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphenylpropionitrile
(53 mg, 0.16 mmol) in CH2Cl2 (0. 25 mL) was mixed with H2SO4
(0.28 mL, 96%) and stirred at 40 °C for 30 h. The mixture was
3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphen-
yl-1-propanamine Trifluoroacetate (27). A solution of 3-[(3-en-
do)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphenylpropio-
nitrile (250 mg, 0.758 mmol) in THF (2.5 mL) was mixed with
BH3 (2.53 mL, 1.5 M in THF, 3.79 mmol) at 0 °C. The mixture
was stirred at room temperature for 20 h and diluted with H2O
(1.0 mL). The solution was then mixed with K2CO3 (0.1 g) and
stirred at room temperature for 1 h. Organic layers were
separated, and the aqueous part was extracted with EtOAc (2
ꢀ 3 mL). The organic layers were combined, dried over Na2SO4,
and concentrated. Purification via a reverse phase HPLC
afforded the title compound (159 mg, 56%). LC/MS (ES) m/z
1
335 (M þ H)þ. H NMR (400 MHz, MeOD-d4) δ ppm 7.45-
7.37 (m, 4 H), 7.36-7.30 (m, 2 H), 7.29-7.20 (m, 4 H), 3.77-
3.65 (m, 5 H), 2.68 (s, 3 H), 2.55 (s, 2 H), 2.34 (s, 4 H), 2.13-1.80
(m, 3 H), 1.37-1.33 (d, J = 15.40 Hz, 2 H).
then poured onto ice, neutralized with NH3 H2O, extracted
3
with EtOAc, and concentrated. The resultant residue was dis-
solved in DMSO and filtered. Purification by reverse phase
HPLC provided the title compound (17.2 mg, 30%). LC/MS
(ES) m/z 347 (M þ H)þ. Purity by LC: 100%. 1H NMR (CDCl3)
δ ppm 7.45-7.32 (m, 10 H), 6.89 (br s, 1 H), 5.82 (br s, 1 H), 3.67
(br s, 2 H), 2.79 (d, J = 5.05 Hz, 2 H), 2.67 (d, J = 4.80 Hz, 3 H),
2.45-2.34 (m, 2 H), 2.34-2.13 (m, 4 H), 2.02-1.94 (m, 1 H),
1.31 (d, J = 15.16 Hz, 2 H).
N-{3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-di-
phenylpropyl}-N0-(phenylmethyl)urea Trifluoroacetate (28a). A
solution of 3-((endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-2,2-
diphenylpropylamine (50.0 mg, 0.149 mmol) in CH2Cl2 (2.0 mL)
was mixed with PhCH2NCO (20.4 μL, 0.164 mmol) and Et3N
(62.8 μL, 0.447 mmol). The resulting mixture was stirred at
room temperature for 1 h and concentrated. Purification by
reverse phase HPLC afforded the title compound (13.0 mg,
19%). LC/MS (ES) m/z 468 (M þ H)þ. Purity by LC: 100%. 1H
NMR (400 MHz, MeOD-d4) δ ppm 7.36-7.29 (m, 6 H), 7.27-
7.20 (m, 9 H), 4.24 (s, 2 H), 3.97 (s, 2 H), 3.62 (br s, 2 H), 2.67 (s, 3
H), 2.49 (d, J = 4.04 Hz, 2 H), 2.31-2.14 (m, 4 H), 1.99-1.80
(m, 3 H), 1.25 (d, J = 14.15 Hz, 2 H). HRMS calcd for
(C31H37N3Oþ) 468.3009, found 468.3013.
(3-endo)-8-Methyl-3-(2,2,2-triphenylethyl)-8-azabicyclo[3.2.1]-
octane Trifluoroacetate (30). A solution of triphenylmethane
(0.276 g, 1.13 mmol) in THF (0.5 mL) was mixed with n-BuLi
(0.706 mL, 1.6 M in hexane, 1.13 mmol). The solution was stirred
for 10 min, and a solution of (endo)-3-iodomethyl-8-methyl-8-
azabicyclo[3.2.1]octane (100 mg, 0.377 mmol) in DMF (1.0 mL)
was added. The mixture was stirred at room temperature for 60
min, mixed with H2O (0.1 mL), concentrated, and filtered.
Purification by reverse phase HPLC afforded the title compound
(23.8 mg, 17%). LC/MS (ES) m/z 382 (M þ H)þ. Purity by LC:
100%. 1H NMR(CDCl3) δ ppm 7.36-7.28 (m, 12 H), 7.26-7.18
(m, 3 H), 3.64 (br s, 2 H), 2.97 (d, J = 5.05 Hz, 2 H), 2.65 (d, J =
4.80 Hz, 3 H), 2.50-1.87 (m, 7 H), 1.08 (d, J = 15.41 Hz, 2 H).
3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphe-
nylpropanoic Acid Trifluoroacetate (31). To a solution of 2-[(3-
endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-1,1-diphenyletha-
nol (100 mg, 1.56 mmol) in HCOOH (0.25 mL) was quickly
added H2SO4 (2.73 mL, 90%) at 0 °C. The reaction vial was
capped immediately and stored in a refrigerator at -20 °C for 7
days. The solution was poured into ice, neutralized with
N-Ethyl-N0-{3-[(3-endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-
2,2-diphenylpropyl}urea Trifluoroacetate (28b). The title com-
pound was prepared from 3-[(3-endo)-8-methyl-8-azabicyclo-
[3.2.1]oct-3-yl]-2,2-diphenylpropylamine and CH3CH2NCO by
following the procedure for compound 28b (45% yield). LC/MS
1
(ES) m/z 406 (M þ H)þ. Purity by LC: 100%. H NMR (400
MHz, MeOD-d4) δ ppm 7.34 (t, J = 7.45 Hz, 4 H), 7.28-7.17 (m,
6 H), 3.94 (s, 2 H), 3.68 (br s, 2 H), 3.08 (q, J = 7.07 Hz, 2 H), 2.68
(s, 3 H), 2.59-2.52 (m, 2 H), 2.33-2.26 (m, 4 H), 2.07-1.84 (m,
3 H), 1.33 (d, J = 15.16 Hz, 2 H), 1.03 (t, J = 7.20 Hz, 3 H).
N-{3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-di-
phenylpropyl}acetamide Trifluoroacetate (28c). A solution of
3-[(3-endo)-8-methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphenyl-
propylamine (33.4 mg, 0.10 mmol) in CH2Cl2 (0.5 mL) was
mixed with Ac2O (18.9 μL, 0.20 mmol) and pyridine (16.2 μL,
0.20 mmol). The mixture was stirred at room temperature for 1 h
and concentrated. Purification via a reverse phase HPLC
afforded the title compound (10.7 mg, 29%). LC/MS (ES) m/z
377 (M þ H)þ. Purity by LC: 100%. 1H NMR (400 MHz,
MeOD-d4) δ ppm 7.35-7.31 (m, 4 H), 7.27-7.21 (m, 6 H), 4.00
(s, 2 H), 3.66 (s, 2 H), 2.67 (s, 3H), 2.53-2.52 (d, J = 3.80 Hz,
2 H), 2.26 (s, 4 H), 1.97-1.95 (m, 3 H), 1.82 (s, 3 H), 1.28-1.24
(d, J = 15.7 Hz, 2 H).
NH3 H2O, extracted with EtOAc, and concentrated. The re-
3
sultant residue was dissolved in DMSO and filtered. Purification
by reverse phase HPLC then afforded the title compound (52
mg, 48%). LC/MS (ES) m/z 350 (M þ H)þ. Purity by LC: 100%.
1H NMR (400 MHz, MeOD-d4) δ ppm 7.46-7.20 (m, 10 H),
3.69 (br s, 2 H), 2.84 (d, J = 5.31 Hz, 2 H), 2.69 (s, 3 H), 2.34-
2.27 (m, 4 H), 2.02-1.94 (m, 2 H), 1.90-1.80 (m, 1 H), 1.40 (d,
J = 15.41 Hz, 2 H).
3-[(3-endo)-8-Methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphen-
yl-1-propanol Trifluoroacetate (32). A mixture of 3-[(3-endo)-8-
methyl-8-azabicyclo[3.2.1]oct-3-yl]-2,2-diphenylpropionic acid

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 16 5251
(42.5 mg, 0.122 mmol) and LiAlH4 (0.488 mL, 1.0 M in THF,
0.488 mmol) was heated with a microwave reactor at 100 °C for
1 h. It was diluted with saturated Na2SO4 solution, filtered
through Celite, and concentrated. The resultant residue was
dissolved in DMSO and filtered. Purification by reverse phase
HPLC then afforded the title compound (29.1 mg, 71%). LC/
MS (ES) m/z 336 (M þ H)þ. Purity by LC: 100%. 1H NMR (400
MHz, CDCl3) δ ppm 7.39-7.21 (m, 7 H), 7.17-7.08 (m, 3 H),
4.17 (s, 2 H), 3.73 (br s, 2 H), 2.70 (d, J = 4.80 Hz, 3 H), 2.62-
2.56 (m, 2 H), 2.44-2.19 (m, 6 H), 1.98-1.87 (m, 1 H), 1.41 (d,
J = 15.41 Hz, 2 H).
Supporting Information Available: Elemental analysis data
for compounds 18 and 34 and general methods for the in vitro
and in vivo assays. This material is available free of charge via
the Internet at http://pubs.acs.org.
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1
Purity by LC: 100%. H NMR (400 MHz, MeOD-d4) δ ppm
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7.50 (d, J = 7.33 Hz, 4 H), 7.43 (t, J = 7.96 Hz, 4 H), 7.40-
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The authors also thank Dulcie Schmidt for excellent techni-
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