Antimuscarinic 3-(2-Furanyl)quinuclidin-2-ene derivatives: Synthesis and structure-activity relationships

Article abstract of DOI:10.1021/jm970346t

A series of 25 derivatives of the muscarinic antagonist 3-(2- furanyl)quinuclidin-2-ene (4) was synthesized and evaluated for muscarinic and antimuscarinic properties. Substitution at all three positions of the furan ring has been investigated. The affini

Full text of DOI:10.1021/jm970346t

3804
J . Med. Chem. 1997, 40, 3804-3819
An tim u sca r in ic 3-(2-F u r a n yl)qu in u clid in -2-en e Der iva tives: Syn th esis a n d
Str u ctu r e-Activity Rela tion sh ip s
Gary J ohansson,† Staffan Sundquist,‡ Gunnar Nordvall,† Bjo¨rn M. Nilsson,† Magnus Brisander,§
Lisbeth Nilvebrant,‡ and Uli Hacksell*,†,|
Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Center, Uppsala University, Box 574,
S-751 23 Uppsala, Sweden, Department of Pharmacology, Pharmacia & Upjohn AB, S-751 82, Uppsala, Sweden, and
Department of Structural Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91, Stockholm, Sweden
Received May 27, 1997X
A series of 25 derivatives of the muscarinic antagonist 3-(2-furanyl)quinuclidin-2-ene (4) was
synthesized and evaluated for muscarinic and antimuscarinic properties. Substitution at all
three positions of the furan ring has been investigated. The affinities of the new compounds
were determined by competition experiments in homogenates of cerebral cortex, heart, parotid
gland, and urinary bladder from guinea pigs using (-)-[3H]-3-quinuclidinyl benzilate as the
radioligand, and the antimuscarinic potency was determined in a functional assay on isolated
guinea pig urinary bladder using carbachol as the agonist. Several of the novel derivatives
displayed high muscarinic affinities. Whereas the affinity of lead compound 4 for cortical
muscarinic receptors is moderate (Ki ) 300 nM), it is much higher for the 5-methyl (48; Ki )
12 nM), 5-ethyl (52; Ki ) 7.4 nM), 5-bromo (33; Ki ) 6.4 nM), and 3-phenyl (49; Ki ) 2.8 nM)
substituted derivatives. The substituent-induced increases in affinity do not appear to be
additive as a 5-bromo-3-phenyl (54), and a 5-methyl-3-phenyl (55) substitution pattern only
slightly increases affinity (Ki ) 1.55 and 2.39 nM, respectively). The conformational preferences
of the 3-phenyl (49) and 5-phenyl (51) derivatives were studied by X-ray crystallography and
molecular mechanics calculations. Because of the observed high affinity of 49, a series of 16
meta- and para-substituted analogues of 49 was synthesized and tested. The m-hydroxy
derivative (68) exhibited more than 10-fold improvement in affinity as compared to 49. The
structure-activity relationships of the new series are well described with QSAR and CoMFA
models.
In tr od u ction
substituted analogues 3 and 48. The introduction of a
5-methyl substituent in 4, producing 48, led to a 25-
fold increase in affinity, whereas a 5-methyl substituent
(producing 3) caused only a 4-fold enhancement of the
muscarinic affinity in the 2-thienyl derivative 2 (Table
3). These findings led to the present study of structure-
activity relationships (SAR) of substituted derivatives
of 4. An additional aim of this study was to extend the
SAR derived from a series of substituted benzofuranyl
derivatives2 by exploring areas in space not previously
studied.
Recently, we explored the ability of achiral quinucli-
din-2-ene derivatives, substituted with various mono-
and bicyclic aromatic rings, to bind to muscarinic
receptors.1,2 In this series, 3-(benzofuran-2-yl)quinu-
clidin-2-ene (1) is the most potent muscarinic antago-
nist, having affinities (Ki values) for muscarinic recep-
tors ranging from 9.6 nM (cortex) to 67 nM (urinary
bladder) in the various tissue preparations studied.1 The
most potent analogue with a monocyclic heteroaromatic
ring was the 2-thienyl-substituted derivative 2 (Ki ) 290
nM), but the 2-furanyl derivative 4 also had a similar
affinity for cortical muscarinic receptors (Ki ) 300 nM).
The new compounds were investigated for their ability
to displace (-)-[3H]-3-quinuclidinyl benzilate [(-)-[3H]-
QNB] from muscarinic receptors in the cerebral cortex,
heart, parotid gland, and urinary bladder from guinea
pigs. In addition, the antimuscarinic potencies were
evaluated in a functional assay on the isolated guinea
pig bladder.
Ch em istr y
Syn t h esis. The syntheses of the substituted 3-(2-
furanyl)quinuclidin-2-ene derivatives required access to
a number of different 2-bromofuran derivatives (5-17,
Table 1). The preparations of furan derivatives 5,3 6,4
9,3,4 14,5 15,6 16,7 and 178 have been described previ-
ously.
Attempts to increase the affinity of 1 by introduction
of various substituents in the benzofuranyl ring did not
improve the affinity for muscarinic receptors.2 In order
to investigate if substitution in the heteroaromatic ring
might enhance the affinity of the 2-thienyl (2) and
2-furanyl (4) derivatives, we prepared the 5-methyl-
2-Bromo-3-furoic acid (6) was prepared by treating
3-furoic acid with LDA9 and 1,2-dibromotetrafluoroeth-
ane10 (Scheme 1). The ester derivatives 7 and 14 were
obtained by esterification of the corresponding acids,
using dimethyl sulfate in the presence of K2CO3 (7;
† Uppsala University.
‡ Pharmacia & Upjohn AB.
§ Stockholm University.
| Present address: Astra Draco AB, Box 34, S-221 00, Lund, Sweden.
X Abstract published in Advance ACS Abstracts, October 15, 1997.
S0022-2623(97)00346-4 CCC: $14.00 © 1997 American Chemical Society

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3805
Ta ble 1. Yields and Physical Data of Some Bromofuran Derivatives
prepn
recrystn
compd
R3
R4
R5
methoda
% yield
mp, °C
solventsb
formula
C4H3BrO
C5H3BrO3
C6H5BrO3
C11H8BrNO2
C5H3BrO3
C6H5BrO3
C11H8BrNO2
C5H4BrNO2‚1/2H2O
C5H2BrNO
C6H5BrO3
C11H8BrNO2
C5H4BrNO2
C5H2BrNO
5
6
7
8
9
10
11
12
13
14
15
16
17
H
CO2H
CO2Me
CONHPh
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
c
a
a
IA
e
66
32
92
84
59
24
78
44
83
84
59
82
65
oil
160-162d
46-48
A
127-128
130-133f
37-38
CO2H
CO2Me
CONHPh
CONH2
CN
H
H
H
H
B
B
a
IA
IB
II
a
IA
IBi
IIk
150-152
167-169
50-52
CO2Me
CONHPh
CONH2
CN
62-64g
143-144h
144-146j
oil
C
B
a
b
d
See the Experimental Section. A: MeOH/H2O. B: H2O/EtOH. C: MeOH. c Prepared according the literature procedure, ref 3. Lit.4
mp 158 °C. e Prepared according the literature procedure, ref 3a. f Lit.4 mp 130 °C. Lit.5b mp 62.5-63.5 °C. Lit.6 mp 143-144 °C.
g
h
Prepared according the literature procedure, ref 7. Lit.7 mp °C 145-146.5. Prepared according the literature procedure, ref 8.
i
j
k
Sch em e 1a
The syntheses of the novel 3-(2-furanyl)quinuclidin-
2-ene derivatives (Table 2) are outlined in Schemes 3-9.
3-Hydroxyquinuclidine derivatives 20, 21, and 23-29
were synthesized by addition of quinuclidin-3-one to the
appropriate 2-lithiofuranyl derivative, generated by
deprotonation with LDA (method IIIA) or n-BuLi (method
IIIB; Scheme 3).12 Most of the alcohols (20, 22, 24-27,
and 30) were dehydrated to the corresponding quinu-
clidin-2-ene analogues (31, 32, 34, 48, and 51-53) by
heating in concentrated formic acid (method IVA;
Scheme 3).1 The 5-bromo (23), 3-cyano (28), and 5-cyano
(29) derivatives were unstable under acidic conditions.
Therefore, these derivatives were dehydrated by heating
in the presence of Burgess’ reagent13 in THF or benzene
(method IVB), giving 33, 43, and 45 (Scheme 3).
a
Reagents: (a) (i) 2.2 equiv of LDA, THF, -78 °C, (ii) 1,2-
dibromotetrafluoroethane; (b) Me2SO4, K2CO3, acetone; (c) SOCl2,
benzene, reflux; (d) aniline, Et3N.
The 4-bromofuranyl derivative 22 was prepared from
the TMS-protected intermediate 21 (Scheme 4); 3-bromo-
2-lithiofuran, formed by treatment of 3-bromofuran with
LDA,14 was treated with chlorotrimethylsilane to give
3-bromo-2-(trimethylsilyl)furan which was, without pu-
rification, treated with LDA and quenched with quinu-
clidin-3-one to afford 21. Desilylation of 21, using
p-toluenesulfonic acid in methanol, gave 22.15 However,
both desilylation and dehydration of 21, producing 32,
occurred on heating in concentrated formic acid (method
IVA).
Sch em e 2a
Treatment of 3-(2-methyl-1,3-dioxolan-2-yl)furan (18)16
with n-BuLi and subsequent reaction with quinuclidin-
3-one afforded 24, which was both dehydrated and
deprotected in concentrated formic acid (method IVA)
to give 34. More direct approaches to 34, such as
metal-halogen exchange of 31 with n-BuLi and further
reaction with acetyl chloride, Heck coupling of 31 with
butylvinyl ether,17 or Stille-type coupling with (R-
ethoxyvinyl)tributyltin (vide infra) produced mainly
debrominated product.
a
Reagents: (a) Br2, 1,2-dichloroethane, reflux; (b) (i) 20%
aqueous NaOH/MeOH, (ii) concentrated HCl; (c) (i) SOCl2, ben-
zene, reflux, (ii) NH4OH; (d) POCl3, 1,2-dichloroethane, NaCl.
Scheme 1) or iodomethane in the presence of Cs2CO3
(14),11 respectively. The amide derivatives 8, 11, 12,
15, and 16 were prepared by treatment of the appropri-
ate carboxylic acid derivative with thionyl chloride,
followed by addition of aniline (method IA)6 or am-
monium hydroxide (method IB).7
Bromination of methyl furan-3-carboxylate gave a
mixture of mono- and dibromo derivatives3a from which
the monobromo derivative 10 was obtained by distilla-
tion (Scheme 2). Dehydration of the primary amides
12 and 16, using phosphorus oxychloride (method II),
provided the cyano derivatives 13 (Scheme 2) and 17.8

3806 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
Ta ble 2. Yields and Physical Data of Some Novel Quinuclidine Derivatives
general
structure
prepn
recrystn
compd
R
methoda
% yield
mp, °C
solventsb
formula
3
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
73
IVA
IIIA
a
96
82
54
61
78
29
82
62
91
62
33
64
196-198
225-226
118-119
156-158
238-239
218-219
177-178
159-160
94-96
215-217
173-175
186-187
148-149
150-152
125-128
150-151
175-176
166-167
264 dec
A
B
A
C
A
D
A
A
D
F
C12H15NS‚0.5C4H4O4
A
A
A
A
A
A
A
A
A
A
A
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
C
3-Br
4-Br,5-TMS
4-Br
5-Br
c
5-Me
5-Et
5-n-Bu
3-CN
5-CN
5-Ph
3-Br
4-Br
C11H14BrNO2‚0.5(COOH)2‚0.25H2O
C
C
C
C
C
14H22BrNO2Si
a
11H14BrNO2‚(COOH)2‚0.25H2O
11H14BrNO2‚0.5(COOH)2‚0.25H2O
15H21NO4‚0.5(COOH)2‚0.25H2O
12H17NO2‚0.5C4H4O4
IIIA
IIIB
IIIB
IIIB
IIIB
IIIA
IIIA
VII
IVA
IVA
VIII (IVB)e
IVA
a
C13H19NO2‚0.5C4H4O4
C15H23NO2
C12H14N2O2
C12H14N2O2
E
C17H19NO2‚0.25H2O
86
A
A
E
A
A
A
E
A
A
E
A
A
A
A
E
C11H12BrNO‚(COOH)2‚0.75H2O
88 (47)d
40 (27)
53
C11H12BrNO‚(COOH)2
5-Br
C11H12BrNO‚(COOH)2‚0.25H2O
3-COMe
4-COMe
5-COMe
3-CONHPh
4-CONHPh
5-CONHPh
3-CO2Me
4-CO2Me
5-CO2Me
3-CN
4-CN
5-CN
3-Me
4-Me
5-Me
3-Ph
4-Ph
5-Ph
C13H15NO2‚(COOH)2
47
41
C13H15NO2‚(COOH)2
C13H15NO2‚(COOH)2
C18H18N2O2‚HCl
a
VA(VB)
VA(VB)
VC
VA
VA
VC
IVB
VA
IVB (VC)
VI
g
IVA
VII
VII
IVA
IVAh
IVAh
VIII
VI
VII
VII
IX
IX
IX
10 (18)
45 (59)
41
270 dec
238-239
122 dec
C
C
18H18N2O2‚HCl‚0.25H2O
18H18N2O2‚(COOH)2
9 (16)f
19
C13H15NO3‚1.5(COOH)2
C13H15NO3‚(COOH)2
C13H15NO3‚(COOH)2
C12H12N2O‚HCl
167-168
162-163
206-208
186-188
152-154
222-224 dec
141-143
159-160
185-187
177-179
201-202
81-83
163-164
183-184
180-182
140-141
158-159
138-139
138-140
141-145
122-124
223-224
dec
37
36
31
58 (40)
88
40
93
72
55
78
96
73
52
61
83
80
35
57
19
41
34
28
46
46
28
23
38
35
65
88
81
C12H12N2O‚(COOH)2
C12H12N2O‚(COOH)2
A
A
C12H15NO‚(COOH)2‚0.25H2O
C12H15NO‚(COOH)2
C12H15NO‚0.5C4H4O4
C17H17NO‚(COOH)2
A
A
A
A
A
E
E
E
E
E
E
E
E
H
E
E
E
F
C17H17NO‚(COOH)2‚0.5H2O
C17H17NO‚C4H4O4
5-Et
5-n-Bu
C13H17NO‚C4H404‚0.25H2O
C15H21NO‚(COOH)2‚0.25H2O
3-Ph, 5-Br
3-Ph, 5-Me
3-(m-F3CPh)
3-(p-F3CPh)
3-(m-BuOPh)
3-(p-BuOPh)
3-(m-EtPh)
3-(p-EtPh)
3-(m-morpholinoPh)
3-(p-morpholinoPh)
3-(m-NCPh)
3-(p-NCPh)
3-(m-MeCO2Ph)
3-(p-MeCO2Ph)
3-(m-HOPh)
3-(p-HOPh)
3-(m-F3CSO3Ph)
3-(m-MeSO3Ph)
C17H16BrNO‚1.5(COOH)2
C18H19NO‚1.5(COOH)2‚0.25H2O
C18H16F3NO‚(COOH)2
C18H16F3NO‚(COOH)2
C21H25NO2‚(COOH)2
C21H25NO2‚(COOH)2
C19H21NO‚(COOH)2
IX
IX
IX
XA
XA
XB
XB
XI
C19H21NO‚1.5(COOH)2
C21H24N2O2‚2HCl
C
C
21H24N2O2‚HCl‚0.25H2O
18H16NO2‚(COOH)2
175-176
178-179
161-163
180-182
220-222
163-164
186-187
188-190
206-207
C18H16N2O‚1.5(COOH)2
C19H19NO3‚1.5(COOH)2
C19H19NO3‚(COOH)2‚0.4H2O
F
A
F
A
A
A
C
C
17H17NO2‚HCl
XI
a
a
17H17NO2‚1.5(COOH)2
C18H16F3NO4S‚HCl
C18H19NO4S‚HCl‚0.25H2O
IIIB
C12H17NOS‚0.5C4H4O4‚0.5H2O
a
See the Experimental Section. b A: Methanol/ether. B: Methanol/chloroform. C: Acetonitrile/methanol. D: Acetonitrile. E: Ethylacetate/
methanol. F: Acetonitrile/ether. c 3-(2-Methyl-1,3-dioxolan-2-yl). Overall yield calculated from 21 using method IVA. e THF was substituted
d
with benzene as the solvent. f Addition of 1 equiv of silver(I) oxide to the reaction mixture improved the yield. The synthesis of 47 has
g
been described previously.23 However, no pharmacological data on muscarinic properties were reported for this compound. The
h
corresponding hydroxy compound was stirred in concentrated formic acid at room temperature.
Palladium-catalyzed Stille-type coupling reactions
between 3-(tributylstannyl)quinuclidin-2-ene (19)18 and
the appropriate bromofuran derivatives produced amides
(37-39), esters (40-42), and nitriles (44 and 45)
(method VA-C; Scheme 5). In certain reactions, addi-
tion of silver(I) oxide (40)19,20 or cupric oxide20 (method
VB) increased the yields and slightly reduced the
reaction times of the cross-coupling reactions. Attempts
to prepare 37, 38, 40, and 41 by a palladium-catalyzed
carbonylation of 31 and 32 was impractical because of
a low yields (GLC-MS).
The 3-methyl (46) and 3- and 4-phenyl (49 and 50)
substituted derivatives were synthesized by palladium-
catalyzed coupling reactions of the corresponding bromo-
substituted derivatives 31 and 32 with tetramethyltin21
or phenylboronic acids,22 respectively (methods VI and

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3807
Sch em e 3a
Sch em e 6a
a
Reagents: (a) heterocycle, LDA, THF; (b) heterocycle, n-BuLi,
ether; (c) HCOOH, 100 °C; (d) MeO2CNSO2NEt3 (Burgess’ re-
agent), THF or benzene.
Sch em e 4a
a
Reagents: (a) (CH3)4Sn, Pd(OAc)2, tri-o-tolylphosphine, DMF;
(b) ArB(OH)2, Pd(PPh3)4, 2 M aqueous Na2CO3, DME; (c) (i) (R-
ethoxyvinyl)tributyltin, Pd(OAc)2, tri-o-tolylphosphine, DMF, (ii)
1 M aqueous HCl.
Sch em e 7a
a
Reagents: (a) (i) LDA, THF, (ii) chlorotrimethylsilane; (b) (i)
LDA, THF, (ii) quinuclidin-3-one; (c) p-toluenesulfonic acid, MeOH/
H2O.
Sch em e 5a
Reagents: (a) n-BuLi, ether; (b) (i) N,N-dimethylacetamide,
a
(ii) 2.5 M aqueous HCl; (c) 1,2-dibromotetrafluoroethane.
(R-ethoxyvinyl)tributyltin24 followed by acid-catalyzed
hydrolysis of the resulting enol ether (Scheme 6).
Treatment of 4 with n-BuLi in ether followed by
reaction with N,N-dimethylacetamide16 produced acetyl
derivative 36 (Scheme 7). Similarly, reactions of the
5-lithio derivatives of 4 and 49 with 1,2-dibromotet-
rafluoroethane10 produced the 5-bromo-substituted de-
rivatives 33 and 54, respectively (method VIII; Scheme
7).
a
Reagents: (a) Pd(PPh3)4, DMF; (b) Pd(PPh3)4, CuO, DMF; (c)
PdCl2(PPh3)2, dioxane.
Compounds 56-63 were prepared by palladium-
catalyzed Suzuki-type coupling reactions between the
3-bromo derivative 31 and in situ generated aryl borates
(method IX; Scheme 8) or commercially available aryl-
boronic acids (method VII; Scheme 6). Treatment of the
appropriate aryl halide with n-BuLi followed by addition
of triisopropyl borate produced the aryl borates.25
An alternative approach was used to introduce a
phenyl ring substituted with a base-sensitive functional
group (Scheme 9); lithiation of 31 with n-BuLi followed
by treatment with tributyltin chloride produced tin
derivative 72. Palladium-catalyzed cross-coupling reac-
tions of 72 with the appropriate aryl halide produced
the cyano-substituted derivatives 64 and 65 (method
XA) and esters 66 and 67 (method XB). The presence
of CuI as a cocatalyst was essential in the reactions
affording 66 and 67.26
VII; Scheme 6). The 5-methyl-substituted derivative 55
was synthesized from 54 using the conditions described
above (method VI; Table 2). However, attempts to
synthesize the 4-methyl-substituted derivative 47 from
32 using these conditions were unsuccessful because of
competitive debromination; the resulting crude mixture
could be purified neither by crystallization nor by
column chromatography. Instead, 47 was prepared by
using a procedure described by Saunders et al.23 The
5-phenyl-substituted derivative 51 was prepared by a
palladium-catalyzed coupling reaction of alcohol 23 with
phenylboronic acid to give the corresponding alcohol 30,
which was dehydrated in concentrated formic acid
(method IVA) to afford 51. Methyl ketone 35 was
produced by a Stille-type coupling reaction of 32 with

3808 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
Sch em e 8a
differences in conformational preferences would have
to be considered in the subsequent CoMFA studies.
Therefore, we decided to study the conformational
preferences of the 3-phenyl (49, oxalate) and 5-phenyl
(51, fumarate) substituted derivatives in some detail
using experimental (X-ray crystallography) and theo-
retical (molecular mechanics calculations) methods.
The crystal structure of 49 contains two crystallo-
graphically independent complexes (Figure 1). A fitting
of the non-hydrogen atoms of the two protonated 3-(3′-
phenylfuran-2-yl)quinuclidin-2-ene molecules gave a
root mean square (rms) deviation of only 0.08 Å but 1.1
Å for the two oxalate anions, thus indicating analogous
geometry for the cations but slightly different conforma-
tions for the oxalate counterions. The crystal structure
of 51 contains a protonated 3-(5′-phenylfuran-2-yl)-
quinuclidin-2-ene molecule with a fumarate as the
counterion (Figure 2). Bond lengths and torsion angles
indicate a partly conjugated system from the C2-C3
double bond over the furan ring to the phenyl ring for
the protonated cations in both 49 and 51 (Supporting
Information). The angle between the normals of the
least-squares planes of the furan and the phenyl moi-
eties are 38.1(1)° and 40.0(1)° for molecules a and b in
49, respectively, but only 6.8(2)° in 51. The deviation
from the planarity of the conjugated part in 49 is
predominantely due to the steric interactions between
H2 in the quinuclidin-2-ene moiety and H11′ in the
phenyl group.
a
Reagents: (a) (i) n-BuLi, THF, (ii) B(OiPr)3; (b) Pd(PPh3)4, 2
M aqueous Na2CO3, DME, reflux.
Sch em e 9a
a
Reagents: (a) (i) n-BuLi, ether, (ii) tributyltin chloride; (b) m-
or p-bromobenzonitrile, Pd(PPh3)4, DMF, 100 °C; (c) m- or p-
iodophenyl acetate, Pd2dba3, AsPh3, CuI, DMF, 50 °C.
The steric interactions between H11′ and H2 is not
present in 51, in which the conjugated part adopts a
nearly planar arrangement. The atoms in 51 that
deviate most from a least-squares plane through the
conjugated system (the phenyl group, the furan moiety,
C2 and C3) of the non-hydrogen atoms are C2, 0.144(1)
Å, and C11′, 0.141(2) Å, located on opposite sides of the
plane.
The crystal structures are held together by hydrogen
bonds between the quinuclidin-2-ene moiety and the
oxalate/fumarate anions on one hand, and between
either the oxalate or the fumarate anions, on the other.
In addition to the these strong hydrogen bonds, both
Hydrolysis of 66 and 67 gave phenols 68 and 69,
respectively (method XI). Treatment of 68 with N-
phenyltrifluoromethanesulfonimide27 or methanesul-
fonyl chloride28 in the presence of Et3N produced triflate
70 and mesylate 71, respectively.
Con for m a tion a l An a lysis. Certain substitutions in
the 3- and/or 5-positions of the furan ring of 4 led to
particularly high muscarinic affinities (vide infra).
Introduction of a bulky substituent in the 3-position of
the furan ring in 4 might change the conformational
preferences, whereas substitutions in the 4- and 5-posi-
tions of the furan ring should not. Such potential
F igu r e 1. Stereoscopic representation of the solid state conformers of 49, a and b. The atom labeling is shown in a . The
displacement ellipsoids are represented at 50% probability level.

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3809
F igu r e 2. Stereoscopic representation of 51. The displacement ellipsoids are drawn at 50% probability level.
49 and 51 have several potential C-H‚‚‚O interactions
(Supporting Information).
(m1 40%, m2 30%, m3 5%, m4 20%) as found with
immunoprecipitation.34,35 The heart expresses a homo-
geneous population of the m2 subtype, in rat and
rabbit.36,37 Parotid gland contains 93% of m3, deter-
mined with specific antibodies for m1-m5, in rat.38 In
the urinary bladder the predominant subtype is m2.
However, a smaller population of m3 is present, in rat,
rabbit, guinea pig, and human bladder.39
We calculated energy contour maps of the torsion
angle C2-C3-C2′-C3′ versus C2′-C3′-C6′-C11′ or
C4′-C5′-C6′-C11′ for 49 and 51, respectively. The
calculations were performed on the free bases of 49 and
51 with the MM2* force field as implemented in the
MacroModel program29 using a dielectric constant of 1.
The largest difference between the crystal structure
conformations and the computationally derived confor-
mations with the lowest calculated energies was found
in 49. In the crystal structure of 49 the furan oxygen
atom is located opposite to the protonated quinuclidin-
2-ene nitrogen, but in the conformation with the lowest
calculated energy the oxygen atom is close to the
nitrogen atom. The energy difference between the
minimized crystal structure and the global energy
minimum is 4.5 kJ /mol. According to the MM2* calcu-
lations, an energy increase of approximately 3 kJ /mol
is necessary to force the furan ring to become coplanar
with the C2-C3 double bond in the quinuclidin-2-ene
ring in 49. In contrast, the lowest energy conformation
derived from the calculations is almost identical to the
solid state conformation observed in the crystal struc-
ture of 51, but the molecular mechanics calculations
predict a planar arrangement of the conjugated system
whereas it was found to be slightly twisted in the solid
state conformation.
Antimuscarinic potencies (expressed as KB values;
Table 3) were evaluated by functional in vitro studies
on isolated guinea pig bladder, using carbachol as the
agonist. In the presence of antagonist, the concentra-
tion-response curves to carbachol were shifted in
parallel toward higher concentrations, but the maximal
responses remained unaffected. Thus, the inhibition
seemed to be competitive since it could always be
overcome by an increase in the carbachol concentration.
None of the compounds exhibited any muscarinic ago-
nist activity in the isolated urinary bladder when tested
in concentrations of 0.5-1000 µM. For comparison,
reference data for 2-4, racemic QNB, and atropine are
included in Table 3.
The present series of quinuclidine derivatives dis-
played a wide range of affinities. The least potent
derivative (39) exhibited an 11-fold decrease in affinity
for cortical muscarinic receptors as compared to lead
compound 4. In contrast, introduction of a 3-(3-hydroxy-
phenyl) substituent in 4, producing 68, the most potent
analogue in the present series, increased the affinity for
cortical muscarinic receptors more than 1100-fold. The
effect of multiple substituents on the furan ring was
briefly examined. 5-Methyl (48), 5-bromo (33), and
3-phenyl (49) substitution in 4 led to potent antagonists.
However, the 5-bromo-3-phenyl (54) and 5-methyl-3-
phenyl (55) derivatives were only slightly more potent
than 49 (Table 3). Thus, the effects of 3- and 5-substit-
uents on affinity do not seem to be additive.
In conclusion, the above studies demonstrate that
both 49 and 51 are able to adopt a conformation in
which the furan ring is coplanar with the double bond
in the quinuclidin-2-ene ring and with the furan oxygen
close to the quinuclidin-2-ene nitrogen. However, such
a conformation of 49 is about 3 kJ /mol above the
calculated (MM2*) global energy minimum.
Resu lts a n d Discu ssion
P h a r m a cologica l Resu lts. Affinities of the com-
pounds (expressed as Ki values; Table 3) for muscarinic
receptors in the cerebral cortex, heart, parotid gland,
and urinary bladder were determined by competition
experiments with (-)-[3H]QNB.30-33 Cerebral cortex in
rat expresses a mixture of muscarinic receptor subtypes
In general, there was a good agreement between
receptor binding data (Ki) and functional data (KB) in
the urinary bladder. The binding data show that the
new compounds exhibited low tissue selectivity. The
most selective muscarinic antagonist in this series, the
4-amide-substituted derivative 38, displayed about 12-

3810 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
Ta ble 3. Affinities (Ki)a for Muscarinic Receptors, Determined by Competition Experiments with (-)-[3H]QNB and Functional in
Vitro Data (KB), Determined on Isolated Urinary Bladder Strips from Guinea Pig vs Carbachol
Ki (nM)
KB (nM)
compd
cerebral cortex
heart
parotid gland
urinary bladder
urinary bladder
2
3
4
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
290 ( 10
73 ( 2
620 ( 110
230 ( 30
390 ( 60
210 ( 20
320 ( 10
15 ( 3
1200 ( 100
3200 ( 300
2460 ( 50
1900 ( 400
220 ( 8
3600 ( 700
120 ( 20
2840 ( 30
2530 ( 40
460 ( 80
2000 ( 400
230 ( 80
575 ( 20
400 ( 80
35 ( 2
6.9 ( 1.6
1600 ( 100
547 ( 5
24 ( 4
48 ( 3
2.4 ( 0.3
3.1 ( 0.1
10.7 ( 0.7
130 ( 20
9.5 ( 2.5
280 ( 50
1.9 ( 0.4
38 ( 6
1200 ( 200
264 ( 0.5
1100 ( 90
420 ( 70
1500 ( 300
1100b ( 200
500 ( 90
330b ( 40
300 ( 70
140 ( 20
130 ( 0.4
6.4 ( 0.2
570 ( 40
1300 ( 200
1100 ( 90
800 ( 70
580 ( 110
3320 ( 90
60 ( 2
850 ( 130
550c ( 30
390 ( 110
215d ( 25
460 ( 80
540 ( 20
260d ( 50
28 ( 4
29 ( 2
nde
2300 ( 20
2400 ( 900
4600 ( 700
1200 ( 100
2600 ( 300
2500 ( 600
nd
4100 ( 700
3100f ( 500
3900 ( 500
nd
nd
nd
nd
nd
nd
nd
nd
>20000
5100 ( 800
nd
nd
2500 ( 200
nd
nd
nd
240 ( 40
2900 ( 900
3900 ( 100
1200 ( 200
3400 ( 700
720 ( 120
1300 ( 200
680 ( 230
64 ( 5
1100 ( 100
810 ( 60
400 ( 80
710 ( 0.7
93 ( 7
520 ( 20
99 ( 8
12 ( 1
2600b ( 300
nd
nd
nd
1300 ( 20
1100g ( 200
670 ( 120
nd
64 ( 16
61d ( 13
2.8 ( 0.5
730 ( 40
330 ( 30
7.4 ( 0.5
17.1 ( 0.7
1.55 ( 0.02
2.39 + 0.07
5.7 ( 1.4
180 ( 60
8.4 ( 2.1
370 ( 50
2.1 ( 0.03
59 ( 12
5.0 ( 0.5
780 ( 140
7.8 ( 1.8
230 ( 70
0.95 ( 0.23
4.2 ( 0.3
0.27 ( 0.06
0.79 ( 0.13
16 ( 1
8.6 ( 0.9
1900 ( 100
970 ( 50
40 ( 1
13 ( 2
2.7h ( 1.0
1765 ( 1
1300i ( 400
1800 ( 200
1000j ( 480
47 ( 5
31 ( 2
nd
58 ( 2
80 ( 3
7.7 ( 1.1
4.4 ( 0.2
25 ( 9
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
18k ( 4
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
830 ( 160
33 ( 6
940 ( 10
6.9 ( 1.3
124 ( 9
10.3 ( 0.8
2760 ( 600
58 ( 3
61
62
63
64
65
66
67
68
69
70
71
(()-QNB
atropine
2.3 ( 0.6
420 ( 110
11 ( 4
190 ( 40
2.2 ( 0.5
3.3 ( 1.0
0.72 ( 0.20
1.12 ( 0.06
25 ( 5
320 ( 130
0.80 ( 0.08
2.20 ( 0.02
0.61 ( 0.01
3.9 ( 0.5
38 ( 10
nd
nd
8.2 ( 0.1
0.051 ( 0.003l
0.32 ( 0.02l
11 ( 3
16 ( 4
0.045 ( 0.003l
0.24 ( 0.01m
0.20 ( 0.02m
0.89 ( 0.06l
0.85 ( 0.005m
1.6 ( 0.1m
a
b
Values are means ( SEM of two to five experiments performed in triplicate. Concentration of antagonists: 100 µM. c Concentration
of antagonists: 100, 1000 µM. Concentration of antagonists: 50, 100 µM. e nd ) not determined. f Concentration of antagonists: 30,
d
g
h
i
100 µM. Concentration of antagonists: 10, 100 µM. Concentration of antagonists: 1 µM. Concentration of antagonists: 10, 30 µM.
j
k
l
m
Concentration of antagonists: 30 µM. Concentration of antagonists: 0.5, 1.0 µM. Value is from ref 31. Value is from ref 32.
fold selectivity for muscarinic receptors in heart versus
parotid gland. Since all compounds except 38 showed
limited tissue selectivity, we used only receptor affinities
for cortex in the SAR analysis.
3-phenylfuranyl derivatives (56, 58, 60, 62, 64, 68, 70,
and 71) were performed using a partial least-squares
(PLS) analysis.40 The three descriptors used in the
experimental design were also used in the analysis. This
resulted in a model41 explaining 96% of the variance in
affinity and with a cross-validated r2 (q2) of 0.795 using
two principal components (see Figure 3).
The analysis of the 4-substituted compounds (includ-
ing the unsubstituted 49) using PLS resulted in a model
explaining 96% of the variance with a cross-validated
r2 (q2) of 0.753 using two principal components (see
Figure 4).42
These analyses show that both 3- and 4-substituted
phenyl derivatives exhibit similar SAR, a small, electron-
donating, and hydrophilic substituent providing opti-
mum affinity. A substituent in the 4-position of the
3-phenyl substituent appears to be less favorable than
in the 3-position since all of these compounds have lower
affinity than the corresponding 3-substituted deriva-
Str u ctu r e-Activity Rela tion sh ip s. In order to
describe the structure-activity relationships (SAR)
within the present series, both traditional QSAR and
3D-QSAR methods were used. The compounds substi-
tuted in the 3- and 4-positions of the 3-phenyl ring (56,
58, 60, 62, 64, 68, 70, 71 and 57, 59, 61, 63, 65, 69)
were analyzed using traditional QSAR. These com-
pounds were part of an experimental design set; the
substituents that were introduced in the 3- or 4-position
of the 3-phenyl group were selected by factorial design
based on three factors (π, σ-para and molar refractivity
[MR]). The final selection of substituents was also
based on the synthetic accessibility. The 3- and the
4-substituted 3-phenyl derivatives were analyzed sepa-
rately. The QSAR analyses of the eight 3-substituted

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3811
Substituting the phenyl group with a 3- or 4-hydroxyl
group, that is, a small, electron-donating, and hydro-
philic group, produced compounds (68 and 69) with high
affinity, possibly because the hydroxyl group partici-
pates in a hydrogen bond interaction with the receptor
protein.43,44
We also included the 13C NMR chemical shifts for the
furan ring carbons of 3-, 4-, and 5-substituted furan
derivatives as descriptors in the QSAR analysis. How-
ever, no improved correlation was found by including
the 13C NMR shift values.
Comparative molecular field analysis (CoMFA)45 was
performed in an attempt to describe the SAR of all
tested compounds.46 The compounds were aligned by
fitting all heavy atoms in the quinuclidin-2-ene ring
using 4 as a template. They were superimposed in the
same energetically accessible rotameric form, the furan
ring being coplanar with the double bond in the quinu-
clidin-2-ene ring and the furan oxygen located close to
the quinuclidin-2-ene nitrogen. This particular confor-
mation was used because it produced the best fit with
our model of the m1 receptor.44 Semiempirical PM3
charges and geometries were used in the study. Con-
formational preferences of the substituents were taken
from dihedral drives using Macromodel29 with subse-
quent minimization using Macromodel and the PM3
Hamiltonian. The compounds were included in a box,
and the steric and electrostatic interactions were evalu-
ated at grid points in the box. The CoMFA analysis was
performed with a grid size of 2 Å using a positively
charged carbon as the probe atom. CoMFA standard
scaling and no column filtering was used in the analysis.
The steric and electrostatic cutoff values were set to +30
kcal/mol. The electrostatic interaction was dropped for
each compound within the steric cutoff values. The
analysis was made with cross-validation using the
“leave one out” procedure. The g2, which is a measure
of the predictive power of a model, was used to evaluate
the models. This value is always lower than the
conventional r2, and a g2 > 0.5 is considered to indicate
a good predictive ability.
F igu r e 3. Plot of actual versus predicted affinities for the
3-substituted 3-phenylfuran derivatives derived from the
QSAR model 1.
The derived CoMFA model gave a g2 ) 0.63 (CoMFA
model 1, Table 4). A correlation coefficient (r2) of 0.92
was found for a plot of actual versus predicted affinity
(Figure 5). Steric and electrostatic factors have similar
contributions to the model (Table 4). Compounds 68
and 69 were among those that were most poorly
predicted. One possible explanation may be that the
CoMFA method underestimates possible hydrogen bond
interactions. It is noteworthy that the QSAR equation
(vide supra) gives a good model and predicts compounds
68 and 69 well without explicity taking into account
hydrogen bonds (no specific hydrogen bond descriptors
are used). However, log P, which is present in the
QSAR equation, is a complex descriptor and is affected
by the hydrogen bond donating/accepting ability of a
substituent.
F igu r e 4. Plot of actual versus predicted affinities for the
4-substituted 3-phenylfuran derivatives derived from the
QSAR model 2.
tives. A large 4-substituent also reduces the affinity
significantly more than the corresponding substituent
in the 3-position (cf. refs 41 and 42). This indicates that
the environment around the phenyl group in the two
series is relatively similar, but the receptor region close
to the 4-position of the phenyl group seems to be
sterically crowded.
Ta ble 4. Summary of CoMFA Results for Models 1-3a
relative contribution
principal
components
standard error
of estimate
F
model
g2
r2
value
steric
electrostatic
1
2
3
0.63
0.61
0.48
4
2
2
0.92
0.86
0.87
0.32
0.38
0.40
98.7
68.4
36.8
0.59
0.52
0.52
0.41
0.48
0.48
a
See Figure 5 for a graphical representation of model 1.

3812 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
decrease the affinity (yellow contours). The red contours
located around both the furan ring and the 3-phenyl
group indicate that these aromatic rings should be
electron rich for optimal affinity.
Two additional CoMFA models were also produced.
CoMFA model 2 (Table 4) includes only the 3-, 4-, and
5-substituted furan derivatives, but the substituted
3-phenyl derivatives are not included. This also pro-
duced a good model (g2 ) 0.61 and r2 ) 0.86). A model
of only the substituted 3-phenyl derivatives (CoMFA
model 3, Table 4) produced a model with reduced g2
(0.48).
Con clu sion . Our studies of antimuscarinic quinu-
clidin-2-ene derivatives substituted in the 3-position
with a heteroaromatic ring1,2 have now been extended
to substituted furan derivatives. In a previous study
of 3-(2-benzofuranyl)quinuclidin-2-ene derivatives,2 sub-
stitutions in the benzofuranyl moiety decreased or did
not affect the affinity for muscarinic receptors. In
contrast, the present study demonstrates that the
affinity of furan derivative 4 for muscarinic receptors
can be enhanced more than 1000-fold by an appropriate
[a 3-(3-OH-phenyl)] substitution in the furan ring.
Furthermore, the SAR of the 41 derivatives described
herein are well described by a CoMFA model (model 1).
This may allow for the design of novel potent antimus-
carinic agents which exhibit receptor-subtype selectiv-
ity, a missing property in the present series of com-
pounds.
F igu r e 5. Plot of actual versus predicted affinities for all
compounds derived from CoMFA model 1.
The CoMFA contour values were chosen from a steric
field distribution histogram to identify contour values
with sufficient data points at a location where the
influence of field properties on affinity is the greatest.
Figure 6 shows that a small or flexible group (such as
an ethyl group) at the 5-position of the furan ring (green
contours) is beneficial for affinity to cortical muscarinic
receptors. Small groups in the 3- and 4-position of the
3-phenyl ring also increase the affinity (the hydroxy
groups). Steric bulk in the 4-position of the furan ring
is detrimental to the affinity (yellow contours). Large
groups in the 4-position of the 3-phenyl ring also
Exp er im en ta l Section
Ch em istr y. Gen er a l Com m en ts. Reactions were carried
out under nitrogen. Tetrahydrofuran (THF) was distilled from
Na/benzophenone ketyl. Melting points were determined in
open glass capillaries on a Thomas-Hoover apparatus. IR
spectra were recorded on a Perkin-Elmer 298 infrared spec-
F igu r e 6. Stereoscopic representation of CoMFA model 1. Included within the CoMFA contours is compound 49. The contour
levels are made using actual STDEV*COEFF values. The red electrostatic contours (-0.010) indicate areas where negative groups
are beneficial for activity, i.e., where they lower the Ki value. Blue contours (0.040) indicate areas where positive groups increase
the affinity. The green contours (0.050) indicate areas where an increase in bulk would increase the activity. Yellow contours
(-0.020) indicate areas where steric bulk is detrimental to the biological activity.

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3813
trophotometer or on a Perkin-Elmer 1600 series FTIR. Most
1H and 13C NMR spectra were recorded on a J EOL J NM-EX
270 spectrometer at 270.2 and 67.9 MHz, respectively. Some
NMR spectra were also recorded on a J EOL FX 90Q spec-
trometer at 22.5 MHz, or on a J EOL J NM-EX 400 spectrom-
eter at 399.95 and 100.5 MHz, respectively. 1H and 13C NMR
spectra were referenced to internal tetramethylsilane. Diox-
reflux for 3.5 h. The solution was filtered and concentrated
under reduced pressure. Bulb-to-bulb distillation (bp 78-82
°C/∼17 mm) gave 313 mg (83%) of 13 as an oil which solidified
in the freezer: TLC Rf ) 0.82 [SiO2, n-pentane/ether (9:1)];
MS (free base), m/ z 173 (M+ 81Br), 171 (M+ 79Br); IR (KBr disk)
1
2244 cm-1; H NMR (270 MHz, CDCl3) δ 7.92 (d, J ) 1 Hz, 1
H), 6.56 (d, J ) 1 Hz, 1 H); 13C NMR (67.9 MHz, CDCl3) δ
150.82, 125.12, 112.18, 111.70, 100.64. Anal. (C5H2BrNO) C,
H, N.
1
ane was used as internal reference for H and 13C NMR spectra
(3.60 and 68.0 ppm, respectively) recorded in D2O. All spectra
were in accordance with the assigned structures. Low-
resolution electron-impact mass spectral data (70 eV) were
obtained on a Hewlett-Packard mass spectrometer HP5971A
MSD connected to a gas chromatograph HP GC5890 series 2,
equipped with a HP-1 (25 m × 0.2 mm i.d.) column. Thin-
layer chromatography was carried out on aluminum sheets
precoated with silica gel 60 F254 (0.2 mm) or aluminum oxide
60 F254 neutral (type E) (E. Merck). Column chromatography
was performed on silica using Kiselgel 60 (230-400 mesh), E.
Merck, or on alumina: aluminum oxide 90, E. Merck. Chro-
matographic spots were visualized by UV and/or I2 vapor. The
elemental analyses were performed by Mikro Kemi AB,
Uppsala, Sweden, or Analytische Laboratorien, Lindlar, Ger-
many, and were within 0.4% of the calculated values unless
otherwise stated. The following heteroaryl and aryl halides
were prepared according to literature procedures: 5-Bromo-
3-furoic acid,4 5-bromo-2-furancarbonitrile,8 5-bromo-2-furan-
carboxamide,7 4-(4-bromophenyl)morpholine.47 m-Bromobu-
toxybenzene was obtained by alkylation of 3-bromophenol with
1-bromobutane in the presence of K2CO3. p-Iodophenyl acetate
and m-iodophenyl acetate were prepared from the correspond-
ing phenols by acylation with acetyl chloride in the presence
of Et3N.48
Meth od IIIA. 3-(3-Br om ofu r a n -2-yl)qu in u clid in -3-ol
Oxa la te (20). A solution of LDA in THF/n-heptane (1.5 M;
19.5 mL, 29.3 mmol) was added to a stirred solution of
3-bromofuran (4.00 g, 27.3 mmol) in dry THF (50 mL) at -80
°C. After 2.5 h, a solution of quinuclidin-3-one (3.41 g, 27.3
mmol) in dry THF (20 mL) was added. The reaction mixture
was slowly warmed to room temperature. After 10 h, a
solution of saturated aqueous ammonium chloride (3 mL) was
added dropwise, and the mixture was filtered through a pad
of Celite and concentrated under reduced pressure. Column
chromatography of the crude product on Al2O3 with gradient
elution using EtOAc f EtOAc/MeOH (9:1) yielded 6.09 g (82%)
of the pure base which was converted into its oxalate salt and
recrystallized: TLC Rf (free base) ) 0.27 [Al2O3, CHCl3/MeOH
1
(95:5)]; MS (free base), m/ z 273 (M+ 81Br), 271 (M+ 79Br); H
NMR (270 MHz, CD3OD) δ 7.53 (d, J ) 2.0 Hz, 1 H), 6.56 (d,
J ) 2.0 Hz, 1 H), 4.09 (d, J ) 13.9 Hz, 1 H), 3.48-3.10 (m,
partly obscured, 5 H), 2.85-2.82 (m, 1 H), 2.48-2.31 (m, 1
H), 2.04-1.76 (m, 2 H), 1.70-1.53 (m, 1 H); 13C NMR (67.9
MHz, CD3OD) δ 172.38, 152.58, 143.54, 117.09, 98.09, 70.35,
66.94, 47.33, 46.59, 30.89, 21.20, 19.23. Anal. (C11H14
-
BrNO2‚0.5(COOH)2‚1/4H2O) C, H, N.
Meth od IIIB. 3-(5-Meth ylfu r a n -2-yl)qu in u clid in -3-ol
F u m a r a te (25). A solution of n-BuLi in hexane (1.4 M; 16.5
mL, 23.1 mmol) was added dropwise to a stirred solution of
2-methylfuran (2.85 mL, 31.3 mmol) in dry ether (45 mL) at 0
°C. The cooling bath was removed, and the solution was
stirred at room temperature for 4 h. The reaction mixture was
cooled to 0 °C, a solution of quinuclidin-3-one (2.53 g, 20.2
mmol) in ether (25 mL) was added, and the mixture was
stirred at room temperature for 10 h. A solution of saturated
ammonium chloride (15 mL) was added dropwise. The mix-
ture was poured into 2 M aqueous HCl (40 mL) and was
washed with ether (3 × 125 mL). The aqueous layer was made
basic with 5 M aqueous NaOH and was extracted with ether
(5 × 175 mL). The combined organic layers were dried (K2-
CO3), filtered, and concentrated in vacuo. The residue was
purified by column chromatography on Al2O3 with gradient
elution [CHCl3 f CHCl3/MeOH (95:5)] to yield 3.45 g (82%) of
the pure base, which was converted into its fumarate salt and
recrystallized: TLC Rf (free base) ) 0.32 [Al2O3, CHCl3/MeOH
(95:5)]; MS (free base), m/ z 207 (M+); 1H NMR (270 MHz,CD3-
OD) δ 6.65 (s, 1 H), 6.34 (d, J ) 3.1 Hz, 1 H), 6.01-5.98 (m, 1
H), 3.75 (dd, J ) 2.0 and 13.7 Hz, 1 H) 3.40-3.00 (m, partly
obscured, 5 H), 2.48-2.30 (m, 2 H), 2.28 (d, J ) 0.9 Hz, 3 H),
1.93-1.60 (m, 3 H); 13C NMR (22.5 MHz, CD3OD) δ 174.62,
155.07, 153.62, 137.00, 108.68, 107.32, 69.18, 59.08, 47.16,
46.33, 31.96, 21.19, 19.30, 13.47. Anal. (C12H17NO2‚0.5C4H4O4)
C, H, N.
Syn th esis. Below are given representative examples of the
general methods presented in Table 1 and 2.
Meth od IA. 2-Br om o-3-fu r a n ca r boxa n ilid e (8). Thio-
nyl chloride (2 mL, 27.4 mmol) was added to a solution of 6
(1.02 g, 5.34 mmol) in dry benzene (10 mL). The solution was
stirred under reflux for 4 h. The solution was concentrated
under reduced pressure. The residue was dissolved in dry
benzene (10 mL), and a solution of freshly distilled aniline
(1.45 g, 15.6 mmol) and Et3N (1.58 g, 15.6 mmol) in dry
benzene (5 mL) was added dropwise at 0 °C. The resulting
solution was stirred at room temperature for 5 h and was
poured into 1 M aqueous HCl (20 mL). The aqueous phase
was extracted with ether (2 × 50 mL). The combined organic
layers were dried (MgSO4), filtered, and concentrated under
reduced pressure. Purification by flash chromatography on
SiO2 using ether/petroleum ether (1:1) as eluent gave 1.20 g
(84%) of 8 as a pale yellow solid: TLC Rf ) 0.5 [SiO2, ether/
petroleum ether (1:1)]; MS (free base), m/ z 267 (M+ 81Br), 265
(M+ 79Br); IR (KBr disk) 3320, 1648 cm-1; 1H NMR (270 MHz,
CDCl3) δ 8.00 (br s, 1 H), 7.62-7.57 (m, 2 H), 7.49 (d, J ) 2.1
Hz, 1 H), 7.42-7.31 (m, 2 H), 7.21-7.12 (m, 1 H), 6.91 (d, J )
2.1 Hz, 1 H); 13C NMR (67.9 MHz, CDCl3) δ 159.19, 144.83,
137.53, 129.27 (2C), 124.94, 123.21, 121.29, 120.41 (2C),
112.95. Anal. (C11H8BrNO2) C, H, N.
Meth od IB. 5-Br om o-3-fu r a n ca r boxa m id e (12). Com-
pound 12 was prepared from 9 by slow addition of 5-bromo-
3-furoyl chloride to an excess of cold ammonium hydroxide
which resulted in the immediate formation of a white precipi-
tate. The reaction mixture was concentrated, and the residue
was crystallized from aqueous EtOH to give 495 mg (44%) of
12 as a pale yellow solid: TLC Rf ) 0.2 [Al2O3, ether]; MS
(free base), m/ z 191 (M+ 81Br), 189 (M+ 79Br); IR (KBr disk)
Meth od IVA. 3-(3-Br om ofu r a n -2-yl)qu in u clid in -2-en e
Oxa la te (31). The free base of 20 (507 mg, 1.86 mmol) was
dissolved in concentrated formic acid and stirred under reflux
for 4 h. The solution was made basic with 5 M aqueous NaOH
and was extracted with ether (4 × 150 mL). The combined
organic layers were dried (K2CO3), filtered, and concentrated
in vacuo to yield 407 mg (86%) of the pure base as an oil which
solidified in the freezer. The base was converted into the
oxalate salt and recrystallized: TLC Rf (free base) ) 0.7 [Al2O3,
EtOAc/MeOH (95:5)]; MS (free base), m/ z 255 (M+ 81Br), 253
1
3395, 3197, 1652, 1621 cm-1; H NMR (270 MHz, CD3OD) δ
8.07 (br s, 1 H), 6.76 (br s, 1 H); 13C NMR (67.9 MHz, CD3OD)
δ 166.05, 148.43, 126.00, 124.85, 111.70. Anal. Found: C,
30.15; H, 2.15; N, 6.6. C5H4BrNO2‚1/2H2O requires: C, 30.18;
H, 2.41; N, 7.04.
1
(M+ 79Br); H NMR (270 MHz, CD3OD) δ 7.67 (d, J ) 2.0 Hz,
Meth od II. 5-Br om o-3-fu r a n ca r bon itr ile (13). Com-
pound 13 was prepared by the procedure previously used for
the synthesis of 5-bromo-2-furancarbonitrile (17). A mixture
of 5-bromo-3-furancarboxamide (12; 417 mg, 2.19 mmol), NaCl
(155 mg, 2.66 mmol), and 1,2-dichloroethane (15 mL) was
refluxed for 15 min. Phosphorus oxychloride (1.0 mL, 10.7
mmol) was added, and the reaction mixture was stirred under
1 H), 7.32 (app d, 1 H), 6.71 (d, J ) 2.0 Hz, 1 H), 3.96-3.88
(m, 1 H), 3.73-3.58 (m, 2 H), 3.27-3.12 (m, partly obscured,
2 H), 2.24-2.08 (m, 2 H), 1.94-1.77 (m, 2 H); 13C NMR (67.9
MHz, CD3OD) δ 166.50, 145.89, 144.40, 138.16, 125.05, 117.84,
101.76, 51.43 (2C), 27.79, 24.11 (2C). Anal. (C11H12BrNO‚
(COOH)2‚3/4H2O) C, H, N.

3814 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
Meth od IVB. 3-(3-Cya n ofu r a n -2-yl)qu in u clid in -2-en e
Hyd r och lor id e (43). The free base of 3-(3-cyanofuran-2-yl)-
quinuclidin-3-ol (28) (428 mg, 1.96 mmol) in dry THF (30 mL)
was added dropwise to a solution of Burgess’ reagent13 (1.0 g,
4.2 mmol) in dry THF (40 mL). The solution was stirred at
room temperature for 1 h and then under reflux for 6 h. The
crude mixture was concentrated, and the residue was parti-
tioned between 1 M aqueous NaOH and CHCl3. The combined
organic extracts were dried (K2CO3), filtered, and concentrated.
Column chromatography of the crude product on SiO2 using
CHCl3/MeOH (95:5) as eluent gave 141 mg (36%) of the pure
base. The product was converted into its hydrochloride salt
and recrystallized: TLC Rf (free base) ) 0.32 [Al2O3, CHCl3/
MeOH (95:5)]; MS (free base), m/ z 200 (M+); IR (KBr disk)
2235 cm-1; 1H NMR (270 MHz, CD3OD) δ 7.83 (d, J ) 2.0 Hz,
1 H), 7.33 (app d, 1 H), 6.92 (d, J ) 2.0 Hz, 1 H), 3.92-3.85,
(m, 1 H), 3.81-3.66 (m, 2 H), 3.33-3.17 (m, partly obscured,
2 H), 2.30-2.14 (m, 2 H), 1.99-1.82 (m, 2 H); 13C NMR (67.9
MHz, CD3OD) δ 154.09, 146.70, 137.21, 127.71, 114.90, 114.41,
97.02, 51.64 (2C), 27.85, 24.03 (2C). Anal. (C12H12N2O‚HCl)
C, H, N.
obscured, J ) 3.6 Hz, 1 H), 7.10 (br s, 1 H), 3.83 (s, 3 H), 3.53-
3.36 (m, 3 H), 3.05-2.82 (m, 2 H), 2.05-1.89 (m, 2 H), 1.72-
1.55 (m, 2 H); 13C NMR (22.5 MHz, CD3OD) δ 166.53, 160.19,
151.98, 146.45, 137.90, 125.39, 120.48, 113.22, 52.69, 51.73
(2C), 28.47, 24.31 (2C). Anal. (C13H15NO3‚(COOH)2) C, H, N.
Meth od VI. 3-(3-Meth ylfu r a n -2-yl)qu in u clid in -2-en e
Oxa la te (46). A mixture of the free base of 31 (930 mg, 3.66
mmol), Pd(OAc)2 (16 mg, 0.071 mmol), P(o-tolyl)3 (89 mg, 0.29
mmol), Et3N (509 µL, 3.66 mmol), and Me4Sn (1.3 g, 7.32
mmol) in DMF (5 mL) was heated at 100 °C for 36 h in a sealed
flask. The mixture was diluted with dioxane, filtered through
Celite, and concentrated under reduced pressure. The residue
was purified by repetitive column chromatography on SiO2
with gradient elution using CHCl3 f CHCl3/MeOH (9:1) to
yield 612 mg (88%) of pure base as a pale yellow solid. The
product was converted into the oxalate salt and recrystal-
lized: TLC Rf (free base) ) 0.45 [SiO2, CHCl3/MeOH (85:15)];
1
MS (free base), m/ z 189 (M+); H NMR (270 MHz, CD3OD) δ
7.53 (d, J ) 1.7 Hz, 1 H), 6.81 (br s, 1 H), 6.44 (d, J ) 1.7 Hz,
1 H), 3.78-3.56 (m, 3 H), 3.34-3.16 (m, partly obscured, 2
H), 2.28-2.10 (m, 5 H), 1.94-1.76 (m, 2 H); 13C NMR (67.9
MHz, CD3OD) δ 166.15, 144.40, 143.66, 139.84, 123.29, 121.72,
Met h od VA. 3-(4-Cya n ofu r a n -2-yl)q u in u clid in -2-en e
Oxa la te (44). A mixture of 5-bromo-3-furancarbonitrile (13)
(105 mg, 0.61 mmol) and Pd(PPh3)4 (70 mg, 0.061 mmol) in
DMF (3 mL) was stirred at 100 °C. A solution of 3-(tributyl-
stannyl)quinuclidin-2-ene (19)18 (403 mg, 1.01 mmol) in DMF
(1 mL) was added to the reaction mixture after 5 min. The
mixture was heated at 100 °C for 48 h in a sealed flask, diluted
with dioxane, filtered through a pad of Celite, and concentrated
in vacuo. The residue was purified by repetitive chromatog-
raphy on SiO2 using CHCl3/MeOH (9:1) as eluent. The crude
base was converted into the oxalate salt and recrystallized.
This afforded 61.9 mg (31%) of 44: TLC Rf (free base) ) 0.44
[SiO2, CHCl3/MeOH (9:1)]; MS (free base), m/ z 200 (M+); IR
116.75, 51.86 (2C), 28.07, 24.03 (2C), 11.86. Anal. (C12H15
-
NO‚(COOH)2
‚1/ H O) C, H, N.
4
2
Meth od VII. 3-[3-(4-(Tr iflu or om eth yl)p h en yl)fu r a n -2-
yl]qu in u clid in -2-en e Oxa la te (57). Pd(PPh3)4 (332 mg 0.29
mmol) was added to a stirred solution of the free base of 31
(1.22 g, 4.80 mmol) in 1,2-dimethoxyethane (15 mL). After
10 min, 4-(trifluoromethyl)benzeneboronic acid (1.00 g, 5.26
mmol) and 2 M aqueous Na2CO3 (10 mL) were added, and the
reaction mixture was stirred under reflux for 3 h. The mixture
was concentrated and partitioned between 1 M aqueous HCl
(50 mL) and ether (50 mL). The aqueous layer was made basic
with K2CO3 and extracted with CHCl3 (3 × 150 mL). The
combined organic layers were dried (K2CO3), filtered, and
concentrated. The residue was purified by column chroma-
tography, first on SiO2 using EtOAc/MeOH (9:1) as eluent and
then on Al2O3 using ether as eluent, to yield 1.22 g (80%) of
the base which was converted into the oxalate and recrystal-
lized: TLC Rf (free base) ) 0.51 [SiO2, CHCl3/MeOH (9:1)];
1
(KBr disk) 2241 cm-1; H NMR (270 MHz, CD3OD) δ 8.39 (s,
1 H), 7.20 (s, 1 H), 7.11 (s, 1 H), 3.75-3.40 (m, 3 H), 3.35-
3.20 (m, partly obscured, 2 H), 2.23-2.06 (m, 2 H), 1.91-1.73
(m, 2 H); 13C NMR (67.9 MHz, CD3OD) δ 166.72, 153.39,
150.58, 137.30, 125.12, 113.31, 112.02, 100.90, 51.84 (2C),
28.57, 24.28 (2C). Anal. (C12H12N2O‚(COOH)2) C, H, N.
Meth od VB. 3-[4-(N-P h en ylca r ba m oyl)fu r a n -2-yl]qu i-
n u clid in -2-en e Hyd r och lor id e (38). A mixture of 5-bromo-
3-furancarboxanilide (11) (435 mg, 1.64 mmol), Pd(PPh3)4 (189
mg, 0.164 mmol), and CuO (130 mg, 1.64 mmol) in DMF (8
mL) was stirred at 100 °C in a sealed flask. After 5 min, a
solution of 19 (781 mg, 1.96 mmol) in DMF (1 mL) was added.
The reaction mixture was heated at 100 °C for 7 h. The
mixture was diluted with dioxane, filtered through Celite, and
concentrated in vacuo. The residue was purified by repetitive
column chromatography on SiO2 with gradient elution using
CHCl3 f CHCl3/MeOH (9:1) as eluent and then on Al2O3 with
EtOAc as eluent. This provided 283 mg (59%) of the pure base
as a white solid. The base was converted into the hydrochlo-
ride salt and recrystallized: TLC Rf (free base) ) 0.20 [SiO2,
CHCl3/MeOH (9:1)]; MS (free base), m/ z 294 (M+); IR (KBr
disk) 3255, 1640 cm-1; 1H NMR (270 MHz, CD3OD) δ 8.33 (s,
1 H), 7.72-7.60 (m, 2 H), 7.43-7.27 (m, 3 H), 7.20-7.09 (m, 1
H), 7.02 (s, 1 H), 3.78-3.46 (m, 3 H), 3.35-3.12 (m, partly
obscured, 2 H), 2.28-2.08 (m, 2 H), 1.94-1.76 (m, 2 H); 13C
NMR (67.9 MHz, CD3OD) δ 162.42, 149.68, 148.34, 139.48,
138.22, 129.88 (2C), 126.25, 125.73, 122.91, 122.15 (2C),
110.89, 52.15 (2C), 28.63, 24.20 (2C). Anal. (C18H18N2O2‚HCl‚
1/4H2O) C, H, N.
1
MS (free base), m/ z 319 (M+); H NMR (270 MHz, CD3OD) δ
7.80-7.72 (m, 2 H), 7.70 (d, J ) 1.9 Hz, 1 H), 7.66-7.60 (m, 2
H), 6.93 (app d, 1 H), 6.69 (d, J ) 1.9 Hz, 1 H), 3.70-3.52 (m,
2 H), 3.26-3.06 (m, 3 H), 2.10-1.70 (m, 4 H); 13C NMR (67.9
MHz, CD3OD) δ 166.50, 145.24, 143.82, 138.85, 138.63, 131.20
(q, J C,F ) 33 Hz), 130.63 (2C), 127.38, 126.82 (q, J C,F ) 4.2 Hz,
2C), 125.57 (q, J C,F ) 271 Hz, CF3), 124.83, 115.50, 51.62 (2C),
28.41, 24.20 (2C). Anal. (C18H16F3NO‚(COOH)2) C, H, N.
Meth od VIII. 3-(5-Br om o-3-p h en ylfu r a n -2-yl)qu in u -
clid in -2-en e Sesqu ioxa la te (54). A solution of n-BuLi in
hexane (1.6 M; 1.61 mL, 2.58 mmol) was added dropwise to a
stirred solution of 49 (500 mg, 1.99 mmol) in dry ether (50
mL) at -70 °C. The cooling bath was removed, and the
solution was stirred at room temperature for 4 h. The reaction
mixture was cooled to -70 °C, and 1,2-dibromotetrafluoroeth-
ane (0.38 mL, 3.97 mmol) was added dropwise. The mixture
was allowed to slowly reach room temperature over 10 h. The
reaction was quenched by addition of water (5 mL) and
concentrated under reduced pressure. The residue was puri-
fied by column chromatography on SiO2
using gradient elution
[CHCl3 f CHCl3/MeOH (9:1)] to give 342 mg (52%) of the pure
base of 54. The product was converted into the oxalate and
recrystallized: TLC Rf (free base) ) 0.37 [SiO2, CHCl3/MeOH
1
(95:5)]; MS (free base), m/ z 331 (M+ 81Br), 329 (M+ 79Br); H
Meth od VC. 3-(5-(Meth oxyca r bon yl)fu r a n -2-yl)qu in u -
clid in -2-en e Oxa la te (42). To a stirred solution of 19 (3.43
g, 8.61 mmol) in dioxane (50 mL) were added methyl 5-bro-
mofuran-2-carboxylate (14; 1.76 g, 8.61 mmol) and PdCl2-
(PPh3)2 (0.18 g, 0.26 mmol). The reaction mixture was refluxed
for 5 days. The mixture was concentrated under reduced
pressure. The residue was purified by column chromatography
on Al2O3 with CHCl3 as eluent and then on SiO2 using CHCl3/
MeOH (9:1) as eluent. This provided 0.74 g (37%) of the pure
base as an oil which was converted into the oxalate salt and
recrystallized: TLC Rf (free base) ) 0.42 (Al2O3, CHCl3); MS
NMR (270 MHz, CD3OD) δ 7.51-7.38(m, 5 H), 6.87 (app d, 1
H), 6.66 (s, 1 H), 3.67-3.52 (m, 2 H), 3.26-3.04 (m, 3 H), 2.02-
1.71 (m, 4 H); 13C NMR (67.9 MHz, CD3OD) δ 165.01, 145.30,
138.29, 133.26, 131.44, 130.04 (2C), 129.95 (2C), 125.50,
124.29, 117.43, 51.75 (2C), 28.05, 24.15 (2C). Anal. (C17H16
-
BrNO‚1.5(COOH)2) C, H, N.
Meth od IX. 3-[3-(4-Bu toxyp h en yl)fu r a n -2-yl]qu in u cli-
d in -2-en e Oxa la te (59). A solution of n-BuLi in hexane (1.6
M; 15 mL, 24 mmol) was added over 5 min to a stirred solution
of p-bromobutoxybenzene (5.0 g, 21.8 mmol) in dry THF (100
mL) at -78 °C. After 20 min, triisopropyl borate (6.67 mL,
28.3 mmol) was added, and the mixture was stirred at -78
1
(free base), m/ z 233 (M+); IR (KBr disk) 1727 cm-1; H NMR
(270 MHz, DMSO-d6) δ 7.41 (d, J ) 3.6 Hz, 1 H), 7.12 (d, partly

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3815
°C for 3 h. The reaction was quenched by addition of water (2
mL) and concentrated. The residue was dissolved in 1,2-
dimethoxyethane (30 mL), and the free base of 31 (5.03 g, 19.8
mmol), Pd(PPh3)4 (1.38 g, 1.19 mmol), and 2 M aqueous Na2-
CO3 (15 mL) were added. The reaction mixture was refluxed
for 3 h, concentrated, and extracted with CHCl3 (3 × 150 mL).
The combined organic layers were dried (K2CO3), filtered, and
concentrated. The residue was purified by repetitive column
chromatography, first on SiO2 using CHCl3/MeOH (9:1) as
eluent and then on Al2O3 using EtOAc as eluent, to yield 3.64
g (57%) of pure base. The product was converted into the
oxalate and recrystallized: TLC (free base) Rf ) 0.59 [SiO2,
CHCl3/MeOH (9:1)]; MS (free base), m/ z 323 (M+); IR (KBr
4 H); (67.9 MHz, CD3OD) δ 159.80, 145.67, 143.84, 140.35,
136.51, 131.84, 130.25, 124.05, 121.86, 117.53, 117.12, 116.58,
52.81 (2C), 29.82, 24.96 (2C). Anal. (C17H17NO2‚HCl) C, H,
N.
Syn th etic P r oced u r e for Com p ou n d s Not P r ep a r ed by
Gen er a l Meth od s: 4-(3-Br om op h en yl)m or p h olin e. This
compound was prepared using a slight modification of a
procedure reported for the synthesis of 4-(4-bromophenyl)-
morpholine. A mixture of 3-bromoaniline (17.2 g, 0.1 mol), 2,2′-
dichlorodiethyl ether (14.4 g, 0.1 mol), and 2 M aqueous NaOH
(80 mL) was heated under reflux for 5 days. The cooled
mixture was extracted with ether (4 × 100 mL). The combined
ether layers were dried (MgSO4), filtered, and concentrated.
The residue was purified by repeated column chromatography
on SiO2 using n-pentane/ether (75:25) as eluent to give an oil.
The crude product was converted into the hydrochloride salt
and recrystallized from MeCN/MeOH. The crystals were
treated with 1 M aqueous NaOH, and the free base was
extracted with ether. The organic layer was dried (K2CO3),
filtered, and concentrated to give 5.8 g (24%) of pure 4-(3-
bromophenyl)morpholine as an oil: TLC Rf (free base) ) 0.50
[SiO2, CHCl3/MeOH (9:1)]; MS (free base), m/ z 243 (M+ 81Br),
241 (M+ 79Br); 1H NMR (free base; 270 MHz, CDCl3) δ 7.12
(dd, J ) 8.0 Hz, 1 H), 7.04-6.92 (m, 2 H), 6.88-6.86 (m, 1 H),
3.88-3.79 (m, 2 H), 3.18-3.09 (m, 2 H); 13C NMR (free base;
1
disk) 1245 cm-1; H NMR (270 MHz, CD3OD) δ 7.60 (d, J )
1.9 Hz, 1 H), 7.25-7.20 (m, 2 H), 7.05-6.80 (m, 2 H), 6.56 (d,
J ) 1.9 Hz, 1 H), 4.00 (t, J ) 6.3 Hz, 2 H), 3.67-3.50 (m, 2 H),
3.25-3.05 (m, 3 H), 2.04-1.42 (m, 8 H), 0.99 (t, J ) 7.3 Hz, 3
H); 13C NMR (67.9 MHz, CD3OD) δ 166.52, 160.72, 144.66,
142.91, 139.30, 131.13, 128.97, 126.31, 123.44, 115.89, 115.80,
68.82, 51.73(2C), 32.49, 27.96, 24.20(2C), 20.32, 14.21. Anal.
(C21H25NO2‚(COOH)2) C, H, N.
Meth od XA. 3-[3-(4-Cya n op h en yl)fu r a n -2-yl]qu in u cli-
d in -2-en e Sesqu ioxa la te (65). A mixture of stannane de-
rivative 72 (803 mg, 1.73 mmol), Pd(PPh3)4 (200 mg, 0.173
mmol), p-bromobenzonitrile (314 mg, 1.73 mmol), and DMF
(4 mL) was stirred in a sealed flask for 24 h at 100 °C. The
reaction mixture was concentrated, and the residue was
purified by repetitive column chromatography on SiO2 using
CHCl3/MeOH (9:1) as eluent to yield 219 mg (46%) of the base
which was converted into its oxalate salt and recrystallized:
TLC (free base) Rf ) 0.40 [SiO2, CHCl3/MeOH (9:1)]; MS (free
67.9 MHz, CDCl3
) δ 152.40, 130.29, 123.19, 122.46, 118.27,
113.96, 67.57 (2C), 49.71 (2C). Anal. (C10H12BrNO) C, H, N.
2-Br om o-3-fu r oic Acid (6). A solution of LDA in THF/n-
heptane (2 M; 89.7 mL, 179.3 mmol) was added over 0.5 h to
a stirred solution of 3-furoic acid (9.14 g, 81.5 mmol) in THF
(250 mL) at -78 °C. After 3 h, 1,2-dibromotetrafluoroethane
was added dropwise, and the mixture was allowed to slowly
reach room temperature over 10 h. The reaction was quenched
by addition of water (2 mL) and concentrated. The residue
was dissolved in water, filtered, and washed with ether (2 ×
10 mL). The aqueous portion was acidified with concentrated
HCl and extracted with ether (4 × 150 mL). The combined
organic layers were dried (MgSO4), filtered, and concentrated
under reduced pressure. The crude product was dissolved in
methanol, decolorized with charcoal, and then crystallized from
aqueous methanol. This gave 4.93 g (32%) of the acid as white
1
base), m/ z 276 (M+); IR (KBr disk) 2228 cm-1; H NMR (270
MHz, CD3OD) δ 7.86-7.78 (m, 2 H), 7.71 (d, J ) 1.9 Hz, 1 H),
7.67-7.59 (m, 2 H), 6.90 (app d, 1 H), 6.70 (d, J ) 1.9 Hz, 1
H), 3.70-3.54 (m, 2 H), 3.27-3.10 (m, 3 H), 2.10-1.94 (m, 2
H), 1.92-1.74 (m, 2 H); 13C NMR (67.9 MHz, CD3OD) δ 165.80,
146.30, 144.83, 140.34, 139.63, 134.67 (2C), 131.75 (2C),
127.99, 125.85, 120.30, 116.15, 113.79, 52.52 (2C), 29.34, 25.05
(2C). Anal. (C18H16N2O‚1.5(COOH)2) C, H, N.
Meth od XB. 3-[3-(3-Acetoxyp h en yl)fu r a n -2-yl]qu in u -
clid in -2-en e Sesqu ioxa la te (66). A mixture of stannane
derivative 72 (3.19 g, 6.87 mmol), Pd2dba3 (252 mg, 0.28 mmol),
AsPh3 (337 mg, 1.10 mmol), and m-iodophenyl acetate (1.80
g, 6.87 mmol) in degassed DMF (15 mL) was stirred at room
temperature. After 5 min, CuI49 (105 mg, 0.55 mmol) was
added, and the mixture was stirred at 50 °C for 60 h. The
reaction mixture was filtered, and the solvent was removed
under reduced pressure. The residue was purified by repeti-
tive column chromatography on SiO2 with gradient elution
using CHCl3 f CHCl3/MeOH (9:1) as eluents to yield 597 mg
(28%) of the base which was converted into the oxalate and
recrystallized: TLC (free base) Rf ) 0.41 [SiO2, CHCl3/MeOH
1
needles: IR (KBr disk) 1689 cm-1; H NMR (270 MHz, CD3-
OD) δ 7.63 (d, J ) 2.1 Hz, 1 H), 6.79 (d, J ) 2.1 Hz, 1 H); 13
C
NMR (67.9 MHz, CD3OD) δ 164.96, 146.29, 130.12, 119.08,
113.96. Anal. (C5H3BrO3) C, H.
Meth yl 2-Br om ofu r a n -3-ca r boxyla te (7). Dimethyl sul-
fate (1.46 g, 11.6 mmol) was added to a suspension of 6 (2.01
g, 10.5 mmol) and K2CO3 (2.9 g, 21.0 mmol) in acetone (50
mL). The reaction mixture was stirred at room temperature
overnight. A solution of ethanol saturated with ammonia (0.5
mL) was added to quench the reaction. Insoluble material was
filtered off, and the acetone was removed under reduced
(9:1)]; MS (free base), m/ z 309 (M+); IR (KBr disk) 1761 cm-1
;
using
pressure. Purification by flash chromatography on SiO2
1H NMR (270 MHz, CD3OD) δ 7.67 (d, J ) 2.0 Hz, 1 H), 7.55-
7.45 (m, 1 H), 7.35-7.08 (m, 3 H), 6.85 (br s, 1 H), 6.65 (d, J
) 2.0 Hz, 1 H), 3.70-3.42 (m, 2 H), 3.38-3.06 (m, partly
obscured, 3 H), 2.29 (s, 3 H), 2.10-1.68 (m, 4 H); 13C NMR
(100.5 MHz, CD3OD) δ 171.29, 165.27, 152.49, 145.13, 143.52,
139.04, 135.77, 131.20, 128.07, 127.41, 124.12, 123.74, 122.49,
n-pentane/ether (9:1) as eluent gave 1.98 g (92%) of 7 as a pale
yellow solid: TLC Rf
) 0.89 [SiO2, n-pentane/ether (9:1)]; MS
(free base), m/ z 206 (M+ 81Br), 204 (M+ 79Br); IR (KBr disk)
1
1733 cm-1; H NMR (270 MHz, CDCl3) δ 7.43 (d, J ) 2.1 Hz,
1 H), 6.77 (d, J ) 2.1 Hz, 1 H), 3.86 (s, 3 H); 13C NMR (67.9
MHz, CDCl3) δ 162.37, 144.35, 129.05, 117.25, 112.68, 51.82.
Anal. (C6H5BrO3) C, H.
115.60, 51.77 (2C) 28.11, 24.23 (2C), 20.96. Anal. (C19H19
-
NO3‚1.5(COOH)2) C, H, N.
Meth yl 5-Br om ofu r a n -3-ca r boxyla te (10). A solution of
Br2 (4.06 g, 25.4 mmol) in 1,2-dichloroethane (10 mL) was
added during 15 min to a boiling solution of methyl furan-3-
carboxylate (3.20 g, 25.4 mmol) in 1,2-dichloroethane (50 mL).
The solution was refluxed for 24 h and then allowed to reach
room temperature. The organic solution was washed with cold
saturated aqueous NaHCO3 and water, then dried (MgSO4),
filtered, and evaporated. The residue was purified by flash
chromatography on SiO2 using n-pentane/ether (9:1) as eluent.
Repeated distillation in a Kugelrohr apparatus gave 1.25 g
(24%) of pure 10 as a pale yellow solid: TLC Rf ) 0.48 [SiO2,
ether/petroleum ether (9:1)]; MS (free base), m/ z 206 (M+ 81Br),
Meth od XI. 3-[3-(3-Hyd r oxyp h en yl)fu r a n -2-yl]qu in u -
clid in -2-en e Hyd r och lor id e (68). A mixture of the free base
of 66 (597 mg, 1.93 mmol), MeOH (10 mL), and 10% aqueous
NaOH (10 mL) was stirred under reflux for 1 h. The MeOH
was evaporated, and the residue was washed with ether (10
mL). The pH of the aqueous layer was adjusted to ∼8.5 with
5 M aqueous HCl and extracted with CH2Cl2 (6 × 75 mL). The
combined organic layers were dried (Na2SO4), filtered, and
concentrated under reduced pressure to give an amorphous
residue. Addition of ethereal HCl produced the hydrochloride
of 68 which was recrystallized: TLC (free base) Rf ) 0.19 [SiO2,
CHCl3/MeOH (9:1)]; MS (free base) m/ z 267 (M+); 1H NMR
(270 MHz, CD3OD) δ 7.63 (d, J ) 2.0 Hz, 1 H), 7.30-7.20 (m,
1 H), 6.90-6.65 (m, 4 H), 6.58 (d, J ) 2.0 Hz, 1 H), 3.70-3.54
(m, 2 H), 3.28-3.08 (m, partly obscured, 3 H), 2.08-1.70 (m,
1
204 (M+ 79Br); IR (KBr disk) 1727 cm-1; H NMR (270 MHz,
CDCl3) δ 7.96 (d, J ) 1.0 Hz, 1 H), 6.67 (d, J ) 1.0 Hz, 1 H),
3.84 (s, 3 H); 13C NMR (67.9 MHz, CDCl3) δ 162.33, 148.64,
123.92, 121.65, 111.36, 52.04. Anal. (C6H5BrO3) C, H.

3816 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
Meth yl 5-Br om ofu r a n -2-ca r boxyla te (14). Iodomethane
(475 mL, 7.86 mmol) was added to a solution of 5-bromofuroic
acid (1.0 g, 5.2 mmol) and Cs2CO3 (2.05 g, 6.29 mmol) in DMF
(15 mL). The reaction mixture was stirred at room temper-
ature overnight. The solution was concentrated under reduced
pressure. The residue was purified by column chromatography
on Al2O3 using ether as eluent to give 0.90 g (84%) of 14 as a
white solid: TLC Rf ) 0.9 [SiO2, n-pentane/ether (9:1)]; MS
(free base), m/ z 206 (M+ 81Br), 204 (M+ 79Br); IR (KBr disk)
3.45 (m, 3 H), 3.37-3.10 (m, partly obscured, 2 H), 2.46 (s, 3
H), 2.24-2.05 (m, 2 H), 1.90-1.74 (m, 2 H); 13C NMR (67.9
MHz, CD3OD) δ 194.34, 167.15, 151.44, 150.51, 138.02, 130.82,
124.04, 109.70, 51.90 (2C), 28.63, 27.76, 24.37 (2C). Anal.
(C13H15NO2‚(COOH)2) C, H, N.
3-(5-Acetylfu r a n -2-yl)qu in u clid in -2-en e Oxa la te (36).
A solution of n-BuLi in hexane (1.6 M; 4.7 mL, 7.52 mmol)
was added dropwise to a stirred solution of the free base of 4
(1.14 g, 6.50 mmol) in dry ether (50 mL) at -30 °C. The cooling
bath was removed, and the solution was stirred at room
temperature for 4 h. The reaction mixture was cooled to -70
°C, and N,N-dimethylacetamide (0.70 mL, 7.55 mmol) was
added. The mixture was allowed to slowly reach room tem-
perature over 10 h. The reaction was quenched by addition
of water (5 mL) and concentrated under reduced pressure. The
residue was stirred with 2.5 M aqueous HCl (15 mL) at room
temperature for 1 h. The solution was made basic by addition
of 5 M aqueous NaOH and extracted with CHCl3 (4 × 50 mL).
The combined organic layers were dried (K2CO3), filtered, and
concentrated in vacuo. Column chromatography of the crude
product on SiO2 using CHCl3/MeOH (9:1) as eluent gave 580
mg (41%) of the pure base. The product was converted into
the oxalate and recrystallized: TLC Rf (free base) ) 0.37 [SiO2,
CHCl3/MeOH (9:1)]; MS (free base), m/ z 217 (M+); IR (KBr
1
1710 cm-1; H NMR (270 MHz, CDCl3) δ 7.10 (d, J ) 3.5 Hz,
1 H), 6.43 (d, J ) 3.5 Hz, 1 H), 3.86 (s, 3 H); 13C NMR (67.9
MHz, CDCl3) δ 158.03, 146.21, 127.52, 120.18, 113.94, 52.11.
Anal. (C6H5BrO3) C, H.
3-(4-Br om o-5-(t r im et h ylsilyl)fu r a n -2-yl)q u in u clid in -
3-ol (21). A solution of LDA (13.6 mL, 2 M, 27.2 mmol) in
THF/n-heptane was added dropwise to a stirred solution of
3-bromofuran (4.0 g, 27.2 mmol) in dry THF (50 mL) at -78
°C. After being stirred for 3 h, chlorotrimethylsilane (3.43 mL,
27.2 mmol) was added. The mixture was allowed to reach
room temperature over 10 h. The reaction mixture was
quenched by addition of water (2 mL), filtered, and concen-
trated. The resulting solution (∼15 mL) was diluted with
petroleum ether (400 mL) and washed with water until
neutral. The organic layer was dried (MgSO4), filtered, and
concentrated. The resulting oil (5.89 g) was dissolved in dry
THF (100 mL), the mixture was cooled down to -78 °C, and a
solution of LDA (14.8 mL, 2 M, 29.6 mmol) in THF/n-heptane
was added dropwise. After 3.5 h, a solution of quinuclidin-3-
one (3.36 g, 26.8 mmol) in dry THF (15 mL) was added. The
mixture was allowed to reach room temperature over 10 h.
The reaction mixture was quenched by addition of water (2
mL), filtered, and concentrated. Column chromatography of
the crude product on Al2O3 using CHCl3 as eluent gave 5.1 g
(54%) of the pure base: TLC Rf (free base) ) 0.57 [Al2O3,
CHCl3/MeOH (95:5)]; MS (free base), m/ z 345 (M+ 81Br), 343
1
disk) 1675 cm-1; H NMR (270 MHz, CD3OD) δ 7.41 (d, J )
3.7 Hz, 1 H), 7.26 (br s, 1 H), 7.04 (d, J ) 3.7 Hz, 1 H) 3.78-
3.52 (m, 3 H), 3.38-3.14 (m, partly obscured, 2 H), 2.48 (s, 3
H), 2.29-2.04 (m, 2 H), 1.94-1.75 (m, 2 H); 13C NMR (67.9
MHz, CD3OD) δ 188.50, 166.56, 154.03, 152.18, 137.97, 125.95,
120.75, 113.60, 51.72 (2C), 28.50, 26.09, 24.31 (2C). Anal.
(C13H15NO2‚(COOH)2) C, H, N.
3-{3-[3-[[(Tr iflu or om eth yl)su lfon yl]oxy]p h en yl]fu r a n -
2-yl}q u in u clid in -2-en e H yd r och lor id e (70). A slurry of
68‚HCl (80 mg, 0.26 mmol), Et3N (1 mL), and CH2Cl2 (10 mL)
was stirred for 1 h at room temperature. N-Phenyltrifluo-
romethanesulfonimide (160 mg, 0.45 mmol) was added, and
the mixture was stirred under reflux for 2.5 h and then at
room temperature for 20 h. The reaction mixture was diluted
with CH2Cl2 (20 mL) and washed with 10% aqueous K2CO3
(10 mL). The organic layer was dried (K2CO3), filtered, and
concentrated under reduced pressure. The residue was puri-
fied by repetitive column chromatography on SiO2 using
gradient elution [CHCl3 f CHCl3/MeOH (9:1)] to give 68 mg
(65%) of the pure base of 70 which was converted into the
hydrochloride and recrystallized: TLC (free base) Rf ) 0.50
[SiO2, CHCl3/MeOH (9:1)]; MS (free base), m/ z 399 (M+); IR
(HCl salt, KBr disk) 1212, 1140 cm-1; 1H NMR (399 MHz, CD3-
OD) δ 7.71 (d, J ) 2.0 Hz, 1 H), 7.68-7.62 (m, 1 H), 7.58-
7.49 (m, 2 H), 7.46-7.40 (m, 1 H), 6.78 (app d, 1 H), 6.68 (d,
J ) 2.0 Hz, 1 H), 3.70-3.54 (m, 2 H), 3.40-3.10 (m, partly
obscured, 3 H), 2.10-1.97 (m, 2 H), 1.91-1.77 (m, 2 H); 13C
NMR (67.9 MHz, CD3OD) δ 151.16, 145.42, 143.88, 139.12,
137.36, 132.38, 130.53, 126.81, 124.63, 123.14, 122.10, 120.23
(q, J C,F ) 320 Hz, CF3), 115.63, 51.82 (2C), 28.23, 24.29 (2C).
Anal. (C18H16F3NO4S‚HCl) C, H, N.
1
(M+ 79Br); H NMR (free base; 270 MHz, CDCl3) δ 6.31 (s, 1
H), 3.33 (dd, J ) 2.0 Hz and 14.4 Hz, 1 H), 3.02-2.05 (m, 8
H), 1.57-1.27 (m, 3 H), 0.33 (s, 9 H,); 13C NMR (free base,
67.9 MHz, CDCl3) δ 163.28, 155.99, 110.79, 110.28, 70.24,
61.08, 46.93, 46.22, 32.42, 23.50, 20.99, -1.39 (3C). Anal.
(C14H22BrNO2Si) C, H, N.
3-(4-Br om ofu r a n -2-yl)qu in u clid in -3-ol Oxa la te (22). A
solution of the free base of 21 (4.96 g, 14.4 mmol), p-
toluenesulfonic acid (10 g 52.6 mmol), MeOH (150 mL), and
water (15 mL) was stirred at room temperature for 6 days.
The MeOH was evaporated, and the mixture was made basic
with 5 M aqueous NaOH and extracted with CHCl3 (5 × 150
mL). The combined organic layers were dried (K2CO3), filtered,
and concentrated under reduced pressure. The crude product
was triturated with ether/n-hexane (1:1) and then recrystal-
lized from EtOAc/MeOH. This gave 2.4 g (61%) of the pure
base which was converted into the oxalate salt and recrystal-
lized: TLC Rf (free base) ) 0.52 [Al2O3, CHCl3/MeOH (95:5)];
MS (free base), m/ z 273 (M+ 81Br), 271 (M+ 79Br); 1H NMR (270
MHz, CD3OD) δ 7.65 (s, 1 H), 6.66 (s, 1 H), 3.85-3.75 (m, 1
H), 3.42-3.24 (m, partly obscured, 5 H), 2.49-2.42 (m, 2 H),
1.99-1.63 (m, 3 H); 13C NMR (67.9 MHz, CD3OD) δ 166.79,
158.33, 142.66, 111.64, 101.40, 69.33, 58.98, 47.53, 46.72,
32.02, 20.86, 19.16. Anal. (C11H14BrNO2‚(COOH)2‚1/4H2O) C,
H, N.
3-{3-[3-[(Meth ylsu lfon yl)oxy]p h en yl]fu r a n -2-yl}qu in u -
clid in -2-en e Hyd r och lor id e (71). A slurry of 68‚HCl (51
mg, 0.168 mmol), Et3N (117 µL, 0.84 mmol), and CH2Cl2 (5
mL) was stirred for 1 h at room temperature. A solution of
methanesulfonyl chloride (22 µL, 0.28 mmol) in CH2Cl2 (1 mL)
was added dropwise at -40 °C. The cooling bath was removed
and the reaction mixture was stirred at room temperature for
1.5 h. The reaction mixture was diluted with CH2Cl2 (20 mL)
and washed with 10% aqueous K2CO3 (10 mL). The organic
layer was dried (K2CO3), filtered, and concentrated under
reduced pressure. The residue was purified by column chro-
matography on SiO2 using gradient elution [CHCl3 f CHCl3/
MeOH (9:1)] to give 51 mg (88%) of the pure base of 71 which
was converted into the hydrochloride and recrystallized: TLC
(free base) Rf ) 0.50 [SiO2, CHCl3/MeOH (9:1)]; MS (free base),
3-(4-Acetylfu r a n -2-yl)qu in u clid in -2-en e Oxa la te (35).
A mixture of the free base of 32 (117 mg, 0.46 mmol), Pd(OAc)2
(2.0 mg, 0.0089 mmol), P(o-tolyl)3 (11.0 mg 0.036 mmol), K2-
CO3 (128 mg, 0.93 mmol), and (R-ethoxyvinyl)tributyltin (312
µL, 0.92 mmol) in dry DMF (2.5 mL) was heated at 100 °C for
24 h in a sealed flask. The DMF was evaporated, and 1 M
aqueous HCl (5 mL) was added. The mixture was stirred at
room temperature for 1 h, made basic with 5 M aqueous
NaOH, and extracted with CH2Cl2. The combined organic
layers were dried (K2CO3), filtered, and concentrated. The
residue was purified by column chromatography on SiO2 using
CHCl3/MeOH (9:1) as eluent to yield 47 mg (47%) of the pure
base which was converted into the oxalate and recrystallized:
TLC Rf (free base) ) 0.36 [SiO2, CHCl3/MeOH (9:1)]; MS (free
m/ z 345 (M+); IR (HCl salt, KBr disk) 1358, 1150 cm-1 1H
;
NMR (270 MHz, CD3OD) δ 7.70 (d, J ) 1.9 Hz, 1 H), 7.61-
7.53 (m, 1 H), 7.47-7.41 (m, 2 H), 7.37-7.31 (m, 1 H), 6.77
(br s, 1 H), 6.69 (d, J ) 1.9 Hz, 1 H), 3.66-3.51 (m, 2 H), 3.40-
3.10 (m, partly obscured, 3 H), 2.12-1.76 (m, 4 H); 13C NMR
δ (100.5 MHz, CD3OD) δ 150.84, 145.39, 143.65, 139.01,
1
base), m/ z 217 (M+); IR (KBr disk) 1670 cm-1; H NMR (270
MHz, CD3OD) δ 8.43 (s, 1 H), 7.18 (s, 1 H), 7.05 (s, 1 H), 3.73-

3-(2-Furanyl)quinuclidin-2-ene Derivatives
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23 3817
136.48, 131.91, 128.93, 127.34, 124.38, 123.96, 122.91, 115.53,
51.81 (2C), 37.97, 28.26, 24.25 (2C). Anal. (C18H19NO4S‚HCl‚1/
4H2O) C, H, N.
the radioligand-induced parallel shift and differences in recep-
tor concentration, using the method of J acobs et al.53 The
binding parameters for (-)-[3H]QNB (KD and receptor densi-
ties) used in these calculations have been determined in
separate series of experiments.30-32
3-(3-(Tr ibu tylstan n yl)fu r an -2-yl)qu in u clidin -2-en e (72).
A solution of n-BuLi in hexane (1.6 M; 3.20 mL, 5.12 mmol)
was added over 5 min to a stirred solution of 31 (1.17 g, 4.60
mmol) in dry THF (50 mL) at -78 °C. After 10 min, tributyltin
chloride (1.38 mL, 5.13 mmol) was added, and the mixture was
stirred at -78 °C for 2 h. The cooling bath was removed, and
the reaction was quenched by addition of water (2 mL). The
mixture was concentrated and partitioned between water (30
mL) and ether (3 × 100 mL). The combined organic layers
were dried (K2CO3), filtered, and concentrated. The residue
was purified by repetitive column chromatography on SiO2
using ammonia-saturated ether as eluent to give 1.42 g (66%)
of 72 as an oil. An aliquot was subjected to bulb-to-bulb
distillation (bp 200-210 °C/∼0.5 mm) to give the analytical
sample: TLC (free base) Rf ) 0.55 [SiO2, CHCl3/MeOH (9:1)];
1H NMR (free base; 270 MHz, CDCl3) δ 7.51 (d, J ) 1.7 Hz, 1
H), 6.75 (d, J ) 1.7 Hz, 1 H), 6.37 (d, J ) 1.7 Hz, 1 H), 3.17-
2.91 (m, 3 H), 2.72-2.57 (m, 2 H), 1.80-0.80 (m, 31 H); 13C
NMR (free base; 67.9 MHz, CDCl3) δ 155.69, 141.54, 139.96,
136.85, 117.48, 111.25, 49.27 (2C), 29.07 (3C), 28.55, 28.14
(2C), 27.31 (3C), 13.68 (3C), 10.23 (3C). Signals due to C-Sn
F u n ction a l in Vitr o Stu d ies. Male guinea pigs, weighing
about 300 g, were killed by a blow to the neck and exsan-
guinated. Smooth muscle strips of the urinary bladder were
dissected in a Krebs-Henseleit solution (pH 7.4). The strip
preparations were mounted vertically between two hooks in
thermostatically controlled (37 °C) organ baths (5 mL). One
of the hooks was adjustable and connected to a force trans-
ducer (FT 03, Grass Instruments). The Krebs-Henseleit
solution was continuously bubbled with carbogen gas (93.5%
O2/6.5% CO2) to maintain the pH at 7.4. Isometric tension
was recorded by a Grass Polygraph (Model 79D). A resting
tension of approximately 5 mN was initially applied on each
muscle strip, and the preparations were allowed to stabilize
for at least 45 min. The resting tension was adjusted, and
the preparations were washed several times during the
stabilization. The urinary bladder strips were used for evalu-
ation of antimuscarinic activity (see Pharmacological Results).
Carbachol (carbamylcholine chloride) was used as the agonist.
Concentration-response curves to carbachol were generated
by cumulative dose-response technique.
In studies of antagonism, a control concentration-response
curve to carbachol was generated by cumulative addition of
carbachol to the bladder strip (i.e., stepwise increase of the
agonist concentration until the maximal contractile response
was reached), followed by washing out and a resting period of
at least 15 min prior to addition of a fixed concentration of
the test compound (antagonist) to the organ bath. After 60
min of incubation with antagonist, a second cumulative
concentration-response curve to carbachol was generated.
Responses were expressed as percent of the maximal response
to carbachol. EC50 values for carbachol in the absence (control)
and presence of antagonist were graphically derived, and dose
ratios (r) were calculated. Dissociation constants, KB, for the
antagonists were then calculated by KB ) [A]/(r - 1), where
[A] is the concentration of the test compound.54
couplings were observed but are not indicated. Anal. (C23H39
NOSn) C, H, N.
-
Com p u ta tion a l Meth od s. The PLS analyses were per-
formed in Simca-S for Windows version 6.0.50 Dihedral drives
and energy minimizations were performed in Macromodel
5.0.29 The PM3 calculations were performed in SPARTAN
4.1.1.51 Sybyl 6.2 was used for the CoMFA analysis. The
docking was made manually using Sybyl 6.2.
P h a r m a cology. Mu sca r in ic Recep tor Bin d in g Stu d -
ies. The tissue preparations and the general methods used
have been described in detail elsewhere for the parotid gland,30
urinary bladder,31 heart,32 and cerebral cortex.32 Male guinea
pigs (250-400 g of body weight) were killed by a blow to the
neck and exsanguinated. The brain was placed on ice for
dissection of the cerebral cortex (gray matter only). Urinary
bladders, hearts, and parotid glands were dissected in a Krebs-
Henseleit buffer (pH 7.4) containing 1 mM phenylmethane-
sulfonyl fluoride (PMSF; Sigma), a protease inhibitor. The
Krebs-Henseleit buffer was composed of (mM) the following:
NaCl 118.0, KCl 5.36, CaCl2 2.52, MgSO4 0.57, NaH2PO4 1.17,
NaHCO3 25.0, and glucose 11.1. Dissected tissues were
homogenized in an ice-cold sodium-potassium phosphate
buffer (50 mM, pH 7.4) containing 1 mM PMSF, using a
Polytron PT-10 instrument (bladder, heart, parotid) and a
Potter-Elvehjem Teflon glass homogenizer (cortex). All ho-
mogenates were diluted with ice-cold phosphate/PMSF buffer
to a final protein concentration of e0.3 mg/mL and were
immediately used in the receptor-binding assays. Protein was
determined by the method of Lowry et al.52 using bovine serum
albumin as the standard.
The muscarinic receptor affinities of the unlabeled com-
pounds were derived from competition experiments in which
the ability to inhibit the receptor specific binding of (-)-[3H]-
QNB (3-quinuclidinyl [phenyl-4-3H]benzilate, 32.9-45.4 Ci/
mmol) was monitored as previously described.32,33 Each
sample contained 10 µL of (-)-[3H]QNB solution (final con-
centration 2 nM), 10 µL of a solution of test compound, and
1.0 mL of tissue homogenate. Triplicate samples were mixed
and incubated in a water bath or in a cool incubator under
conditions of equilibrium (times in cool incubator are noted in
parentheses), i.e., at 25 °C for 60 (80) (urinary bladder), 80
(100) (heart and cerebral cortex), or 210 (240) (parotid gland)
min. Nonspecific binding was determined in the presence of
10 µM unlabeled atropine. Incubations were terminated by
centrifugation31 or rapid filtration onto GF/B filter plates. The
radioactivity in the pellets, respective in the filter plates, was
determined by liquid scintillation spectrometry.31
Ackn owledgm en t. The financial support from Phar-
macia AB, Uppsala, is gratefully acknowledged. We
thank Dr. Ingeborg Cso¨regh for helpful discussion
concerning X-ray crystallography and Ylva Kallin for
skillful assistance in the synthetic work.
Su p p or tin g In for m a tion Ava ila ble: Tables 1-9 showing
data collected by X-ray crystallographic analysis of compounds
49 and 51; fractional atomic coordinates and equivalent
isotropic displacement parameters of the non-hydrogen atoms,
bond lengths and angles, anisotropic displacement parameters
for the non-hydrogen atoms, and fractional atomic coordinates
of the hydrogen atoms; bond distances (Å) and angles (deg)
for possible hydrogen bonds with esd’s; and 1H NMR and 13C
NMR spectral data for 3, 11, 23, 24, 26-30, 32-34, 37, 39-
41, 45, 47-53, 55, 56, 58, 60-64, 67, 69, and 73 (19 pages).
Ordering information is given on any current masthead page.
Refer en ces
(1) Nilsson, B. M.; Sundquist, S.; J ohansson, G.; Nordvall, G.; Glas,
G.; Nilvebrant, L.; Hacksell, U. 3-Heteroaryl Substituted Qui-
nuclidin-3-ol and Quinuclidin-2-ene Derivatives as Muscarinic
Antagonists. Synthesis and Structure-Activity Relationships. J .
Med. Chem. 1995, 38, 473-487.
(2) Nordvall, G.; Sundquist, S.; J ohansson, G.; Glas, G.; Nilvebrant,
L.; Hacksell, U. 3-(2-Benzofuranyl)quinuclidin-2-ene Deriva-
tives: Novel Muscarinic Antagonists. J . Med. Chem. 1996, 39,
3269-3277.
(3) See, for example: (a) Sornay, R.; Meunier, J . M.; Fournari, P.
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Characterization of Some π-Excessive Heteropolyaromatic Com-
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(4) Gilman, H.; Burtner, R. R. Orientation in the Furan Nucleus.
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2909.
IC50 values (concentration of unlabeled compound producing
50% inhibition of the receptor specific (-)-[3H]QNB binding)
were determined graphically from the experimental concentra-
tion-inhibition curves. Affinities, expressed as the dissocia-
tion constants, Ki, were calculated by correcting the IC50 for

3818 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 23
J ohansson et al.
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(41) The PLS equation for the model is pK
0.17572π - 0.82443MR - 0.84142σ(para).
i(cortex) ) 15.200 -
(42) The PLS equation for the model is pKi(cortex) ) 6.3938 -
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could interact with Trp164. We also identified
hydrogen bond interaction with Ser388 in TM6. This is
a possible
a
variable residue between the subtypes (Ser in m1 and m5, Asn
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3-(2-Furanyl)quinuclidin-2-ene Derivatives
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