Muscarinic subtypes profile modulation within a series of new antagonists, bridged bicyclic derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine

Article abstract of DOI:10.1016/S0968-0896(03)00431-0

A set of new muscarinic antagonists, bridged bicyclic derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine (1), was synthesized and tested to evaluate their affinity and selectivity for M₁, M ₂, M₃ and M₄ receptor subtypes. The conformational constraint of 1 in a bicyclic structure, and the variation in distance and stereochemistry of the active functions allowed us to modulate the selectivity of interaction with the M₁-M₃ receptor subtypes. The most interesting compound was (cis,trans)-2-(2,2-diphenylethyl)-5-methyl-tetrahydro-[1,3]dioxolo[4,5-c] pyrrole oxalate (6), which is equipotent with Pirenzepine on rabbit vas deferens (M₁-putative) but shows a better selectivity profile.

Full text of DOI:10.1016/S0968-0896(03)00431-0

Bioorganic & Medicinal Chemistry 11 (2003) 3901–3911
Muscarinic Subtypes Profile Modulation within a Series of
New Antagonists, Bridged Bicyclic Derivatives of
2,2-Diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine
Alessandro Piergentili, Francesco Gentili, Francesca Ghelfi, Gabriella Marucci,
Maria Pigini, Wilma Quaglia and Mario Giannella*
`
Dipartimento di Scienze Chimiche, Universita degli Studi di Camerino, Via S. Agostino, 1, 62032 Camerino, Italy
Received 8 April 2003; accepted 20 June 2003
Abstract—A set of new muscarinic antagonists, bridged bicyclic derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethyl-
amine (1), was synthesized and tested to evaluate their affinity and selectivity for M1, M2, M3 and M4 receptor subtypes. The con-
formational constraint of 1 in a bicyclic structure, and the variation in distance and stereochemistry of the active functions allowed
us to modulate the selectivity of interaction with the M1–M3 receptor subtypes. The most interesting compound was (cis,trans)-2-
(2,2-diphenylethyl)-5-methyl-tetrahydro-[1,3]dioxolo[4,5-c]pyrrole oxalate (6), which is equipotent with Pirenzepine on rabbit vas
deferens (M1-putative) but shows a better selectivity profile.
# 2003 Elsevier Ltd. All rights reserved.
Introduction
fied. Due to their widespread presence at the peripheral
level and, in particular, the M1 and M3 subtypes in
glandular tissue, M2 in the heart, M2 and M3 in smooth
muscle, and M4 in the lung,7À10 the muscarinic receptors
are attractive therapeutic targets. M2-selective antago-
nists such as, for example, AF-DX 116 may thus be
useful for treating bradycardia;11 the M3-selective ones,
such as Darifenacin, for gastrointestinal disorders,12
and Vamicamide for urinary incontinence;13 Reva-
tropate, selective for the M1 and M3 subtypes, is useful
for treating chronic obstructive pulmonary disease
(COPD)12,14 while Pirenzepine (Chart 1),15,16 a potent
M1 antagonist, but only relatively selective for the other
subtypes,17 has proved to be efficacious in cases of pep-
tic ulcer. Furthermore, due to their widespread presence
in the central nervous system, with the M1 and M4 sub-
types in the cerebral cortex, the M1 subtype in the hip-
pocampus, the M4 one in the striatum, the M2 one in
the cerebellum and brainstem, the M3 one in the tele-
ncephalon, the thalamic nuclei, and the brainstem, and
the M5 one in the substantia nigra,18À22 the muscarinic
receptors play a crucial role in neurodegenerative dis-
eases.23 Inhibitors of acetylcholinesterase,24 as well as
M1-agonists,25 and M2-antagonists,26 are useful in
Alzheimer’s disease, that involves a reduction of choli-
nergic activity.27 Selective inhibition of M2 presynaptic
muscarinic receptors has been shown to enhance
The acetylcholine receptors, traditionally subdivided
into muscarinic and nicotinic classes, play important
roles both in the central and peripheral nervous systems.
The muscarinic receptors, expressed in large amounts in
the parasympathetic nervous system, belong to the
superfamily of receptors coupled to the G proteins
(GPCRs) and, by means of pharmacological and molec-
ular biology techniques, have been divided into five
subtypes, M1–M5, which show a high degree of homol-
ogy across species (mammalian and non mammalian),
as well as across receptor subtypes.1 It has been sug-
gested that the M1, M3, and M5 subtypes couple to
phosphoinositide hydrolysis leading to mobilization of
intracellular calcium, whereas activation of M2 and M4
subtypes inhibits adenylcyclase activity.2 Given the lack
of really selective ligands in particular agonists, the
physiological role of each of the different muscarinic
receptor subtypes has not been fully elucitated yet. Only
recently has the use of muscarinic M1-,3 M2-,4 M3-,5 and
M4-receptor knockout mice6 allowed the role of these
receptors in specific physiological functions to be clari-
*Corresponding author. Tel.: +39-0737-402257; fax: +39-0737-
637345; e-mail: mario.giannella@unicam.it
0968-0896/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0968-0896(03)00431-0

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A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
Chart 1.
acetylcholine levels.28 Finally selective M4-muscarinic
antagonists could be useful in treating Parkinson’s
disease.29
could be enhanced;31 at the same time, we had already
noted that compounds with a restricted flexibility such
as 2, in which the nitrogen atom of 1 was included in a
pyrrolidine ring, behave like muscarinic antagonists.32
Therefore, knowing that compounds with a hindered
conformational flexibility can lead to the identification
of the bioactive conformation at the receptor33 and,
hence, to a more specific recognition of receptor-sub-
type binding sites, we designed and synthesized the new
muscarinic antagonists 3–15 (Chart 1), bridged bicyclic
derivatives of 1. In these derivatives, the amine function
In the present study, we have taken as reference
compound 2,2 - diphenyl - [1,3] - dioxolan - 4 - ylmethyl-
dimethylamine (1) (Chart 1), whose methiodide 1a is
known to be a potent but only slightly selective mus-
carinic receptor antagonist.30 In a previous work, we
demonstrated that by appropriately varying the distance
and stereochemistry of the interacting functions (benz-
hydryl group and nitrogen atom) of 1, M1-selectivity
of
1 was incorporated in the pyrrolidine ring,
Scheme 1. (i) TsOH, (ii) CH3NH2.

A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
3903
analogously to what had already occurred with 232
(compounds 3–8) or in the piperidine one (compounds
9–15). In addition, the distance between essential struc-
tural moieties, and the stereochemistry of the aromatic
area with respect to annulation, were modified in order
to investigate their role in potency and selectivity.
Chemistry
The new compounds 3–8 were synthesized according to
Scheme 1. Condensation of meso-1,4-dichloro-butane-
2,3-diol34 with commercially available diphenyl-acetal-
dehyde, 3,3-diphenyl-propionaldehyde,35 4,4-diphenil-
butyraldehyde36 afforded the intermediates 16–18,
respectively, which were cyclized with methylamine to
give compounds 3–8.
The structures of the amines 3 and 4 were satisfactorily
determined by 1D-nuclear Overhauser effect (1D-NOE)
measurements.37 The H-2–H-4 and H2–H5 cis
relationships in compound 3 were demonstrated by the
observation that irradiation of H-2 caused NOE at H-4
and H-5 (1%) (Fig. 1). On the contrary, in compound 4
irradiation of H-2 caused no NOE effect at H-4 and
H-5. Furthermore, in the pair 3–4 the H-2 of trans iso-
mer 4 was deshielded with respect to the same proton in
cis isomer 3: d 5.97 in 4 and d 5.51 in 3 with a difference
Figure 1. Principal correlations observed in the NOE spectrum of
compounds 3 and 10. The numeration refers to the dioxolane cycle
and not to the bicyclic one.
Scheme 2. TsOH, (ii) LiAlH4.
Scheme 3. (i) TsOH, (ii) LiAlH4.

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A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
Table 1. Structures and affinity valuesa for the oxalate compounds 1–15 at muscarinic receptor subtypes
Compd
n
m
Stereoisomer
M1
M2
M3
M4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
7.15Æ0.12b
5.92Æ0.14
5.80Æ0.09b
5.92Æ0.09b
6.48Æ0.20
7.80Æ0.13b
6.13Æ0.11
5.48Æ0.17
7.11Æ0.03b
6.24Æ0.05
5.49Æ0.06b
6.21Æ0.13b
5.84Æ0.12
5.14Æ0.04b
5.86Æ0.13
5.24Æ0.13
7.50Æ0.12b
6.98Æ0.01
7.07Æ0.17
7.30Æ0.08b
5.40Æ0.17
6.30Æ0.03
5.94Æ0.15
6.48Æ0.008b
6.38Æ0.08b
6.21Æ0.07
7.00Æ0.06b
7.25Æ0.06b
5.96Æ0.04
6.18Æ0.12b
5.75Æ0.13
5.78Æ0.12
6.41Æ0.11b
7.00Æ0.06
7.40Æ0.08
5.97Æ0.24b
5.18Æ0.10
6.06Æ0.13
5.89Æ0.06
6.91Æ0.03b
5.20Æ0.09
<5
<5
5.43Æ0.06
5.30Æ0.19
5.21Æ0.19
<5
—
0
0
1
1
2
2
—
0
0
1
1
1
1
1
1
1
2
2
2
2
2
2
2
—
cis
trans
cis
trans
cis
trans
—
cis
trans
cis
trans
cis
trans
<5
5.71Æ0.12
b
6.50Æ0.20
5.79Æ0.14
6.86Æ0.11
6.30Æ0.06b
5.73Æ0.10
5.88Æ0.13
5.57Æ0.14
8.05Æ0.014b
<5
5.38Æ0.12
5.59Æ0.14
5.10Æ0.08
<5
<5
6.36Æ0.02b
1
1
2
2
15
Pirenzepinec
aThese values represent Àlog Kb obtained at 10 mM concentration of the antagonist from the expression log (DRÀ1)=log [ant.]Àlog Kb according to
van Rossum.44 Dose–ratio (DR) values represent the ratio of the potency of the (EC50) in the presence of the antagonist and in its absence.
bpA2 values.
cPirenzepine dihydrochloride (TOCRIS).
of about 0.5 ppm. The structures of the new compounds
1
isomers 13 and 15 were deshielded with respect to the
same protons of cis isomers 12 and 14: d 5.11 in 13 and
d 4.79 in 12; d 5.31 in 15 and d 4.98 in 14. The same
difference of about 0.3 ppm is observed in the pairs 12–
13, and 14–15.
5–8 were determined by comparison of their H NMR
spectra with those of compounds 3 and 4. In fact, in the
pairs 5–6 and 7–8 the H-2 of trans isomers 6 and 8 were
deshielded with respect to the same protons in cis iso-
mers 5 and 7: d 5.12 in 6 and d 4.57 in 5; d 5.31 in 8 and
d 4.79 in 7.
The free bases were transformed into the oxalates
and methiodide salts using an excess of oxalic acid or
CH3I.
Compound 9 was synthesized by condensation of
benzophenone dimethyl acetal38 with 1-ethoxycarbon-
ylpiperidine-cis-3,4-diol39 followed by reduction of car-
bamate 19 with LiAlH4 (Scheme 2).
Results and Discussion
Compounds 10–15 were synthesized analogously to
compound 9. The cis and trans isomers 20–25 were
separated through flash chromatography (Scheme 3).
The pharmacological profiles of the new compounds,
studied as oxalates (3–15) (Table 1) and methiodide
salts (3a–15a) (Table 2), were determined in vitro on
stimulated guinea pig left atria (M2-subtype),40 ileum
(M3-subtype),41 lung (M4-subtype),42 and rabbit vas
The structures of the amines 10 and 11 were determined
similarly to those of compounds 3 and 4. In fact, in
compound 10 the irradiation of the doublet peak of H-2
at d 5.59 ppm caused a NOE effect (2%) at H-4 and H-
5, thus indicating a cis relationship between these pro-
tons and, consequently, between the benzhydryl moiety
and the piperidine nucleus (Fig. 1). On the contrary, in
compound 11 irradiation of the doublet peak at d 5.90
ppm of H-2 caused no NOE effect between the same
protons, indicating a trans relationship between the
piperidine nucleus and benzhydryl moiety. Further-
more, the H-2 of trans isomer 11 was deshielded with
respect to the same proton in cis isomer 10: d 5.90in 11
and d 5.59 in 10 with a difference of about 0.3 ppm. The
structures of the new compounds 12–15 were deter-
44
deferens,43 and are expressed in terms of pKb or of
45
pA2 for the more interesting compounds (1, 3, 4, 6, 9,
12, and Pirenzepine). pA2 Values were estimated by
Schild analysis constrained to slope À1.0, as required by
the theory.46 Selectivity ratios for compounds 1, 3, 4, 6,
9, 12, and Pirenzepine are reported in Table 3. For a
long time, the contraction of rabbit vas deferens was
referred to as an effect mediated by M1-receptor sub-
types,43,47 even though some more recent studies attri-
bute the same effect to an M4-activation;48 at the
present moment, the pharmacological characterization
still does not appear to be definitively established. Thus,
in this work, the rabbit vas deferens muscarinic receptor
subtype will be considered an M1-putative. The study
on lung (M4-subtype) was extended also to compounds
1, 1a, 2, and 2a32 for purposes of comparison.
1
mined in a similar way. In fact, in the H NMR spectra
of the pairs 12–13 and 14–15 the protons H-2 of trans

A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
3905
Table 2. Structures and affinity valuesa for the methiodide compounds 1a–15a at muscarinic receptor subtypes
Compd
n
m
Stereoisomer
M1
M2
M3
M4
1a
2a
3a
4a
5a
6a
7a
8a
8.36Æ0.07
7.62Æ0.01
6.62Æ0.12
7.39Æ0.19
6.51Æ0.18
6.37Æ0.09
6.17Æ0.03
5.43Æ0.07
7.58Æ0.01
7.41Æ0.01
8.00Æ0.15
7.08Æ0.10
5.63Æ0.16
5.55Æ0.01
5.37Æ0.13
8.29Æ0.06
7.66Æ0.01
7.13Æ0.12
7.00Æ0.20
6.81Æ0.20
6.38Æ0.20
5.79Æ0.04
5.71Æ0.20
7.92Æ0.09
7.42Æ0.01
7.34Æ0.11
6.81Æ0.23
6.58Æ0.17
5.96Æ0.14
5.68Æ0.17
7.91Æ0.07
7.62Æ0.05
7.33Æ0.07
7.15Æ0.10
6.71Æ0.08
6.28Æ0.13
5.45Æ0.10
6.36Æ0.03
7.16Æ0.11
7.55Æ0.18
7.75Æ0.18
6.66Æ0.04
6.03Æ0.14
5.81Æ0.14
5.82Æ0.10
6.13Æ0.08
5.57Æ0.11
6.20Æ0.15
5.49Æ0.18
5.54Æ0.07
5.30Æ0.13
5.50Æ0.20
<5
5.69Æ0.06
5.49Æ0.04
5.67Æ0.11
6.32Æ0.11
<5
—
0
0
1
1
1
1
—
0
0
1
1
1
1
1
1
1
2
2
2
2
2
2
2
—
cis
trans
cis
trans
cis
trans
—
cis
trans
cis
trans
cis
trans
9a
10a
11a
12a
13a
14a
15a
1
1
2
2
5.06Æ0.06
<5
aThese values represent Àlog Kb obtained at 10 mM concentration of the antagonist from the expression log (DRÀ1)=log [ant.]Àlog Kb according to
van Rossum.44 Dose–ratio (DR) values represent the ratio of the potency of the (EC50) in the presence of the antagonist and in its absence.
Table 3. Affinity valuesa and selectivity ratiosb for compounds 1, 3, 4, 6, 9, 12 and Pirenzepine
Compd
M1
M2
M3
M4
M1/M2
M1/M3
89
M1/M4
M2/M1
M2/M3
81
M2/M4
M3/M1
M3/M2
M3/M4
1
3
4
6
9
12
7.15 7.11
5.805.49 07.0
5.92
7.805.14
6.507.506.41
6.307.305.97
8.05
6.38
5.201
<5
5.43
6
5
15
16
21
32
11
>100
66
6.21
7.25
6.18
5.21
5.71
5.59
6.91
457
42
389
10
10
12
21
62
51
Pirenzepine
6.48
6.36
37
14
49
apA2 valuesÆSEM were calculated according to Arunlakshana and Schild45 unless otherwise specified, constraining the slope to À1.46 Number of
replications from four to six.
bAntilog of the difference between the pA2 values for M1, M2, M3, M4 muscarinic receptor subtypes.
All the new compounds, analogously to the reference
compound 1, behave as muscarinic antagonists; in par-
ticular, the methiodide salts (3a–15a) mostly display
higher potency together with a lack of selectivity for
tissues with respect to the oxalates. In fact, in the basic
tertiary amines, several chemical modifications (such as
restricting of the conformational freedom of the methyl-
amine chain, variation in the distance and stereo-
chemistry of the interacting functions, and
cyclohomology) to the structure of the potent but only
slightly selective compound 1 have allowed the biologi-
cal profile to be modified and the significantly selective
antagonists to be obtained.
enhanced and more selective M3-interaction compared
with reference compound 1 can be attributed to greater
rigidity of the amine function in the pyrrolidine nucleus
and to a distancing of the interacting functions with a
CH group, that is, to the simultaneous introduction of
two variants, which individually do not produce sig-
nificant selectivity.31,32 The relative spatial arrangement
between the interacting functions does not seem critical
for this subtype selectivity, in so far that the cis isomer
(compound 3) displays similar potency and selectivity
(M3/M1=16-fold; M3/M2=32-fold; M3/M4>100-fold).
Also compounds 10 (cis isomer) and 11 (trans isomer),
piperidine nucleus analogues of 3 and 4, respectively,
maintain non-negligible potency at the M3-muscarinic
subtype (pA2 M3=7.00 and 7.40, respectively), but dis-
play reduced selectivity, since they possess good potency
also at the M2-muscarinic subtype (pA2 M2=6.98 and
7.07, respectively). In compound 9 (M2/M1=10-fold;
M2/M3=12-fold; M2/M4=62-fold) the amine function
of reference compound 1 was incorporated in the
piperidine nucleus: unlike what happens with the more
rigid lower cyclohomologous 2, this modification leads
the ligand to assume a suitable conformation for a
All the compounds examined (both oxalates and
methiodide salts) display low potency at M4-muscarinic
subtype. The structure–activity relationship study of the
ligands 3–15, instead, allowed us to identify the struc-
tural characteristics which favor the interaction with the
M2-muscarinic (compounds 9 and 12), M3-muscarinic
(compounds 3 and 4), and the putative M1-muscarinic
(compound 6) subtypes. With regard to ligand 4 (M3/
M1=21-fold; M3/M2=11-fold; M3/M4=66-fold), the

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A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
extensive aromatic hydrophobic area of 6 and that of
Pirenzepine, the polar functions, that is, the oxygen
atom of dioxolane nucleus of 6 and the nitrogen in
position 1 of the Pirenzepine piperazine ring. Hence it
can be hypothesized that compound 6 and Pirenzepine
interact in a similar way with the M1-muscarinic
receptor.
Conclusion
In the present study, the conformational constraint of 1
in a bicyclic structure, and the variation in distance and
stereochemistry of the critical functions represent fun-
damental operations for modulating the biological pro-
file and obtaining muscarinic antagonists with enhanced
selectivity of interaction with the M1–M3 receptor sub-
types. In particular, the hydrophobic interactions in the
basic tertiary amine derivatives allow the various recep-
tor subtypes to be differentiated: in fact, despite marked
analogies, these seem to display significant differences at
the level of lipophilic binding pockets. The most inter-
esting result of the present study is the behavior of
compound 6, which, equipotent with Pirenzepine, shows
a better M1-putative selectivity profile. Moreover, the
higher lipophilicity of 6 (its calculated value of logP
being 3.6, as compared with the 0.2 of Pirenzepine)51
might facilitate bioavailability at the central level, thus
making this new compound a useful tool for character-
izing the central M1-muscarinic receptor functions that
govern learning acquisition and memory.52 Similarly,
due to their significant M2/M1 selectivity, compounds 9
(ClogP=3.1) and 12 (ClogP=3.8) might be useful in
studies at the central level, since it is well known that
this type of selectivity is crucial in the potential treat-
ment of dementia. Finally, compounds 3 (ClogP=3.1)
and 4 (ClogP=3.1) could be useful for determining the
role played by the central M3 receptors in orexigenic
activity.53
Figure 2. Overlay of pirenzepine and compound 6.
preferred interaction with the M2-muscarinic subtype.
Compound 12 (cis isomer) (M2/M1=10-fold; M2/
M3=21-fold; M2/M4=51-fold) possesses a pharmaco-
logical profile similar to that of 9, probably because the
particular configuration and increased flexibility, due to
the introduction of the CH–CH2 bridge between the
aromatic area and the bicyclic structure, allow the
interacting functions to assume a spatially similar pat-
tern. Instead, unsuitable distances and stereochemistry
seem to be responsible for the low potency of com-
pounds 7, 8, 13, 14, and 15.
The result of the screening of ligand 6 shows a sig-
nificant selectivity on rabbit vas deferens (M1-putative)
(pA2 M1=7.80; M1/M2=457-fold; M1/M3=42-fold;
M1/M4=389-fold). Its pharmacological profile is com-
parable to that of the well-known M1-antagonist Pir-
enzepine, whose profile was determined using the same
experimental protocols (pA2 M1=8.05; M1/M2=37-
fold; M1/M3=14-fold; M1/M4=49-fold), and whose
selectivity derives both from the tricyclic system with
two aromatic areas and from the 4-methyl-1-piperazine
ring.49 Since the basic pyrrolidine ring of 6 can repro-
duce a spatial rigidity similar to that of the Pirenzepine
piperazine ring, it can be hypothesized that, analogously
to Pirenzepine, also in compound 6 the critical functions
for interaction with the M1-muscarinic subtype are pres-
ent and suitably spaced. These analogies were verified
by overlapping the low-energy conformations of com-
pound 6 and Pirenzepine, which were generated using
the HyperChem ‘Molecular Modeling System’.50 Their
molecular overlay (Fig. 2) shows that similar spatial
regions are occupied by the presumed pharmacophores,
such as the basic methylated nitrogen of 6 and the one
in position 4 of the Pirenzepine piperazine ring, the
Experimental protocol
Melting points were taken in glass capillary tubes on a
Buchi B-540apparatus and are uncorrected. IR and
NMR spectra were recorded on Perkin-Elmer 297 and
Varian EM-390instruments, respectively. Chemical
shifts are reported in parts per million (ppm) relative to
tetramethylsilane (TMS), and spin multiplicities are
given as s (singlet), d (doublet), t (triplet), or m (multi-
plet). Although the IR spectra data are not included
(because of the lack of unusual features), they were
obtained for all compounds reported and are consistent
with the assigned structures. The microanalyses were
performed by the Microanalytical Laboratory of our
department and the elemental compositions of the
compounds agreed to withinÆ0.4% of the calculated
value. Chromatographic separations were performed on
silica gel columns (Kieselgel 40, 0.040–0.063 mm,
Merck) by flash chromatography. The term ‘dried’
refers to the use of anhydrous sodium sulfate. Com-
pounds were named following IUPAC rules as applied
by Beilstein-Institut AutoNom (version 2.1), a software

A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
3907
for systematic names in organic chemistry. Overlay of
Pirenzepine and compound 6 was obtained after global
geometry optimisation and energy minimization using
the HyperChem1 MM+ force field method.50
The second fraction was the cis isomer 3: 0.28 g (32%
yield); mp 73–75 ꢀC; H NMR (CDCl3) d 2.12 (m, 2,
1
CH2N), 2.31 (s, 3, NCH3), 3.03 (d, J=11.8 Hz, 2,
CH2N), 4.40(d, J=8.0Hz, 1, ArCH), 4.58 (m, 2,
OCHCHO), 5.51 (d, J=8.0Hz, 1, OCHO), 7.13–7.38
(m, 10, ArH).
Chemistry
(cis,cis/cis,trans)-2-Benzhydryl-4,5 - bis - (chloromethyl) -
[1,3]dioxolane (16). A mixture of diphenyl acetaldehyde
(2.0g, 10.19 mmol), 1,4-dichloro-butane-2,3-diol 34 (1.62
g, 10.19 mmol) and p-toluenesulfonic acid (0.3 g) in
benzene (50mL) was refluxed with vigorous stirring
and water removal for 5 h. After cooling, the solu-
tion was washed with NaHCO3 sol. and dried over
Na2SO4. Evaporation of the solvent gave a residue,
which was purified by column chromatography. Elut-
ing with cyclohexane–CHCl3–EtOAc (9:1:0.1) afforded
16 as a cis/trans mixture (ratio 7:3): 2.4 g (70% yield);
1H NMR (CDCl3) d 3.02–3.72 (m, 8, CH2Cl; cis and
trans), 3.94–4.46 (m, 6, OCHCHO and ArCH; cis and
trans), 5.61 (d, J=3.5 Hz, 1, OCHO; cis), 5.97 (d, J=3.9
Hz, 1, OCHO; trans), 7.19–7.50(m, 20, ArH; cis and
trans).
The free bases were transformed into the oxalates: 3 was
crystallized from MeOH (mp 224–226 ꢀC) and 4 from
EtOH (mp 223–224 ꢀC).
The free bases were transformed into the methiodide
salts: 3a was crystallized from 2-PrOH (mp 215–217 ꢀC)
and 4a from 2-PrOH (mp 203–205 ꢀC).
(cis,cis)- and (cis,trans)-2-(2,2-Diphenylethyl)-5-methyl-
tetrahydro-[1,3]dioxolo[4,5-c]pyrrole oxalates (5 and 6)
and methiodide salts (5a and 6a). 5 and 6 were prepared
as described for 3 and 4 starting from 17 (1.3 g, 3.7
mmol) as a cis/trans mixture. These were separated by
column chromatography eluting with cyclohexane–
EtOAc–MeOH (1:9:0.05) as eluent. The trans isomer 6
eluted first: 0.35 g (30% yield); mp 99–101 ꢀC; 1H NMR
(CDCl3) d 2.13 (m, 2, CCH2C), 2.21 (s, 3, NCH3), 2.32
(dd, J=7.7, J=4.2 Hz, 2, CH2N), 2.90(d, J=11.5 Hz,
2, CH2N), 4.18 (t, 1, ArCH), 4.61 (m, 2, OCHCHO),
5.12 (t, 1, OCHO), 7.12–7.36 (m, 10, ArH).
(cis,cis/cis,trans)-4,5-Bis-(chloromethyl)-2-(2,2-diphenyl-
ethyl)-[1,3]dioxolane (17). 17 was prepared as described
for 16 starting from 3,3-diphenyl propionaldehyde35
(1.25 g, 5.94 mmol). Eluting with petroleum ether–Et2O
(10:0.25) afforded 17 as a cis/trans mixture (ratio 7:3):
1.4 g (67% yield); 1H NMR (CDCl3) d 2.35 (m, 2,
CCH2C; trans), 2.46 (m, 2, CCH2C; cis), 3.66 (m, 8,
CH2Cl; cis and trans), 4.14–4.44 (m, 6, OCHCHO and
ArCH; cis and trans), 4.76 (t, 1, OCHO; cis), 5.08 (t, 1,
OCHO; trans), 7.12–7.30(m, 20, ArH; cis and trans).
The oxalate 6 was crystallized from MeOH (mp 214–
215 ꢀC) and the methiodide salt 6a from MeOH (mp
205–207 ꢀC).
The second fraction was the cis isomer 5: 0.42 g (37%
yield); mp 113–114 ꢀC; H NMR (CDCl3) d 2.03 (m, 2,
1
CCH2C), 2.32 (s, 3, NCH3), 2.53 (dd, J=8.2, J=4.5 Hz,
2, CH2N), 3.11 (d, J=11.8 Hz, 2, CH2N), 4.22 (t, 1,
ArCH), 4.42 (m, 2, OCHCHO), 4.57 (t, 1, OCHO),
7.10–7.37 (m, 10, ArH).
(cis,cis/cis,trans)-4,5-Bis-(chloromethyl)-2-(3,3-diphenyl-
propyl)-[1,3]dioxolane (18). 18 was prepared as described
for 16 starting from 4,4-diphenyl butyraldehyde36 (1.66
g, 7.4 mmol). Eluting with cyclohexane–EtOAc (9:1)
afforded 18 as a cis/trans mixture (ratio 6:4): 2.0g (74%
The oxalate 5 was crystallized from MeOH (mp 242 ꢀC)
and the methiodide salt 5a from MeOH (mp 272–
274 ꢀC).
yield); 1H NMR (CDCl3)
d
1.55–2.27 (m, 8,
CCH2CH2C; cis and trans), 3.61 (m, 8, CH2Cl; cis and
trans), 3.86–4.45 (m, 6, OCHCHO and ArCH; cis and
trans), 5.01 (t, 1, ArCH; cis), 5.34 (t, 1, ArCH; trans),
7.12–7.38 (m, 20, ArH).
(cis,cis)-
and
(cis,trans)-2-(2,2-Diphenyl-propyl)-5-
methyl-tetrahydro-[1,3]dioxolo[4,5-c]pyrrole oxalates (7
and 8) and methiodide salts (7a and 8a). 7 and 8 were
prepared as described for 3 and 4 starting from 18 (2.0
g, 5.48 mmol) as a cis/trans mixture. These were sepa-
rated by column chromatography eluting with cyclo-
hexane–EtOAc–MeOH (1:9:0.05) as eluent. The trans
isomer 8 eluted first: 0.2 g (11% yield); mp 89–90 ꢀC; 1H
NMR (CDCl3) d 1.58 (m, 2, CH2C), 2.06–2.39 (m, 4,
CCH2 and CH2N), 2.32 (s, 3, NCH3), 3.04 (d, J=11.3
Hz, 2, CH2N), 3.90(t, 1, ArCH), 4.63 (m, 2, OCH-
CHO), 5.31 (t, 1, OCHO), 7.10–7.36 (m, 10, ArH).
(cis,cis)- and (cis,trans)-2-Benzhydryl-5-methyl-tetrahy-
dro-[1,3]dioxolo[4,5-c]pyrrole oxalates (3 and 4) and me-
thiodide salts (3a and 4a). A solution of 16 (1.0g, 2.97
mmol) and methylamine (0.18 g, 5.94 mmol) in dry
benzene (20mL) was heated in a sealed tube at 100 ꢀC
for 72 h. Evaporation of the solvent gave a residue,
which was dissolved in CHCl3; the solution was washed
with 2 N NaOH. Removal of the dried solvent gave a
residue, which was an isomeric mixture of the free bases
3 and 4. These were separated by column chromato-
graphy eluting with cyclohexane–EtOAc–MeOH
(1:9:0.05) as eluent. The trans isomer 4 eluted first: 0.25
g (28% yield); mp 113–115 ꢀC; 1H NMR (CDCl3) d 2.07
(m, 2, CH2N), 2.27 (s, 3, NCH3), 3.06 (d, J=11.8 Hz, 2,
CH2N), 4.16 (d, J=4.7 Hz, 1, ArCH), 4.52 (m, 2,
OCHCHO), 5.97 (d, J=4.7 Hz, 1, OCHO), 7.15–7.40
(m, 10, ArH).
The oxalate 8 was crystallized from EtOH/Et2O (mp
196–198 ꢀC) and the methiodide salt 8a from MeOH
(mp 154–156 ꢀC).
The second fractiꢀon was the cis isomer 7: 0.4 g (23%
CH2C), 2.06–2.28 (m, 4, CCH2 and CH2N), 2.35 (s, 3,
1
yield); mp 59–60 C; H NMR (CDCl3) d 1.72 (m, 2,

3908
A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
NCH3), 3.09 (d, J=11.8 Hz, 2, CH2N), 3.93 (t, 1,
ArCH), 4.52 (m, 2, OCHCHO), 4.79 (t, 1, OCHO),
7.09–7.32 (m, 10, ArH).
(cis,cis)- and (cis,trans)-2-(3,3-Diphenyl-propyl)-tetra-
hydro-[1,3]dioxolo[4,5-c]pyridine-5-carboxylic acid ethyl
ester (24 and 25). 24 and 25 were prepared as described
for 19 starting from 4,4-diphenyl butyraldehyde36 (1.8 g,
8.03 mmol). The residue was a cis/trans mixture and the
two isomers were separated by column chromatography
using cyclohexane–EtOAc (9:1) first and (8.5:1.5) then
as eluent. The trans isomer 24 eluted first: 1.2 g (38%
yield); H NMR (CDCl3) d 1.25 (t, 3, CH3), 1.50–2.22
(m, 6, CCH2CH2C and CCH2C), 3.32–3.62 (m, 4,
CH2NCH2), 3.90(t, 1, ArCH), 4.13 (q, 2, OCH ), 4.21
2
(m, 2, OCHCHO), 5.28 (t, 1, OCHO), 7.11–7.36 (m, 10,
ArH).
The oxalate 7 was crystallized from EtOH (mp 187–
188 ꢀC) and the methiodide salt 7a from EtOH (mp
221–222 ꢀC).
1
cis-2,2-Diphenyl-tetrahydro-[1,3]dioxolo[4,5-c]pyridine-5-
carboxylic acid ethyl ester (19). A mixture of benzo-
phenone dimethyl acetal38 (1.21 g, 5.29 mmol), 1-
ethoxycarbonylpiperidine-cis-3,4-diol39 (1.0g, 5.29
mmol) and p-toluenesulfonic acid (0.3 g) in toluene (50
mL) was refluxed in a Stark apparatus with vigorous
stirring for 18 h. After cooling, the solution was washed
with NaHCO3 soln and dried over Na2SO4. Evapora-
tion of the solvent gave a residue, which was purified by
column chromatography. Eluting with cyclohexane–
EtOAc (9:1) first and (5:5) then afforded 19 as an oil: g
The second fraction was the cis isomer 25: 2.0g (62%
1
yield); H NMR (CDCl3) d 1.22 (t, 3, CH3), 1.58–2.26
(m, 6, CCH2CH2C and CCH2C), 3.25–3.77 (m, 4,
CH2NCH2), 3.91 (t, 1, ArCH), 3.99–4.27 (m, 4, OCH2
and OCHCHO), 4.91 (t, 1, OCHO), 7.11–7.33 (m, 10,
ArH).
1
1.5 (80% yield); H NMR (CDCl3) d 1.25 (t, 3, CH3),
1.72–2.23 (m, 2, CCH2C), 3.31–4.05 (m, 4, CH2NCH2,),
4.05–4.37 (m, 4, OCHCHO and OCH2), 7.20–7.66 (m,
10, ArH).
cis-5-Methyl - 2,2 - diphenyl - hexahydro - [1,3]dioxolo[4,5-
c]pyridine oxalate (9) and methiodide salt (9a). A solu-
tion of 19 (1.5 g, 4.24 mmol) in dry Et2O (30mL)
was added dropwise to a stirred mixture of LiAlH4
(0.32 g, 8.48 mmol) in dry Et2O (30mL) at 0 ꢀC
over a period of 15 min. The mixture was refluxed
for 2 h, then decomposed with H2O (0.4 mL), 5 N
NaOH (0.4 mL) and H2O (2.0mL). After stirring for 1
h, the solid was filtered off and the filtrate was dried
over Na2SO4. Removal of solvent gave a residue,
which was purified through column chromatography.
Eluting with CHCl3–MeOH (9.5:0.5) afforded the free
(cis,cis)- and (cis,trans)-2-Benzhydryl-tetrahydro-[1,3]di-
oxolo[4,5-c]pyridine-5-carboxylic acid ethyl ester (20 and
21). 20 and 21 were prepared as described for 19 start-
ing from 2,2-diphenyl acetaldehyde (1.55 g, 7.90mmol).
The residue was a cis/trans mixture and the two isomers
were separated by column chromatography using
cyclohexane–EtOAc (9:1) first and (8:2) then as eluent.
The trans isomer 20 eluted first: 1.0g (35% yield); 1H
NMR (CDCl3) d 1.24 (t, 3, CH3), 1.62–2.0(m, 2,
CCH2C), 3.31–3.58 (m, 4, CH2NCH2), 3.90(m, 2,
OCHCHO), 4.12 (q, 2, OCH2), 4.19 (m, 1, ArCH), 5.89
(d, J=4.8 Hz, 1, OCHO), 7.16–7.40(m, 10, ArH).
base 9: 1.1 g (88% yield); mp 133–135 ꢀC; H NMR
1
(CDCl3) d 1.90–2.86 (m, 6, CH2CH2NCH2), 2.23 (s, 3,
CH3), 4.09–4.43 (m, 2, OCHCHO), 7.20–7.60 (m, 10,
ArH).
The second fraction was the cis isomer 21: 1.6 g (55%
1
yield); H NMR (CDCl3) d 1.24 (t, 3, CH3), 1.62–1.98
The oxalate 9 was crystallized from EtOH (mp 186–
187 ꢀC) and the methiodide salt 9a from 2-PrOH (mp
187–188 ꢀC).
(m, 2, CCH2C), 2.66–3.48 (m, 4, CH2NCH2), 4.12 (q, 2,
OCH2), 4.12–4.33 (m, 2, OCHCHO), 5.52 (d, J=4.4
Hz, 1, OCHO), 7.16–7.39 (m, 10, ArH).
(cis,cis)-2-Benzhydryl - 5 - methyl - hexahydro - [1,3]diox-
olo[4,5-c]pyridine oxalate (10) and methiodide salt (10a).
10 was prepared as described for 9 starting from 21 (1.6
g, 4.35 mmol): 1.0g (74% yield); mp 67–68 ꢀC; 1H
NMR (CDCl3) d 1.14–2.58 (m, 6, CH2CH2NCH2), 2.07
(s, 3, CH3), 4.10(m, 2, OCHCHO), 4.28 (d, J=4.4 Hz,
1, CHAr), 5.59 (d, J=4.4 Hz, 1, OCHO), 7.16–7.39 (m,
10, ArH).
(cis,cis) - and (cis,trans) - 2 - (2,2-Diphenyl-ethyl)-tetra-
hydro-[1,3]dioxolo[4,5-c]pyridine-5-carboxylic acid ethyl
ester (22 and 23). 22 and 23 were prepared as described
for 19 starting from 3,3-diphenyl propionaldehyde35
(1.11 g, 5.28 mmol). The residue was a cis/trans mixture
and the two isomers were separated by column chro-
matography using cyclohexane–EtOAc (9:1) first and
(8:2) then as eluent. The trans isomer 22 eluted first: 0.6
1
g (30% yield); H NMR (CDCl3) d 1.23, (t, 3, CH3),
The oxalate 10 was crystallized from MeOH (mp 190–
191 ꢀC) and the methiodide salt 10a from EtOH (mp
231–232 ꢀC).
1.87 (m, 2, CCH2C), 2.3 (dd, J=8.0, J=4.4 Hz, 2,
CCH2C), 3.28–3.66 (m, 4, CH2NCH2), 4.12 (q, 2,
OCH2), 4.08–4.32 (m, 3, OCHCHO and ArCH), 5.07 (t,
1, OCHO), 7.13–7.36 (m, 10, ArH).
(cis,trans)-2-Benzhydryl - 5 - methyl - hexahydro-[1,3]diox-
olo[4,5-c]pyridine oxalate (11) and methiodide salt (11a).
11 was prepared as described for 9 starting from 20
The second fraction was the cis isomer 23: 1.25 g (62%
1
yield); H NMR (CDCl3) d 1.24, (t, 3, CH3), 1.70–2.05
(m, 2, CCH2C), 2.42 (dd, J=8.2, J=4.5 Hz, 2, CCH2C),
(1.0g, 2.72 mmol): .07 g (83% yield);
1H NMR
(CDCl3) d 1.71–2.62 (m, 6, CH2CH2NCH2), 2.28 (s, 3,
CH3), 3.68–3.98 (m, 2, OCHCHO), 4.19 (d, J=4.0Hz,
1, CHAr), 5.90(d, J=4.0Hz, 1, OCHO), 7.17–7.41 (m,
10, ArH).
3.26–3.80(m, 4, CH NCH2), 4.03–4.28 (m, 5, OCH2,
2
OCHCHO and ArCH), 4.70(t, 1, OCHO), 7.13–7.36
(m, 10, ArH).

A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
3909
The oxalate 11 was crystallized from EtOH (mp 181–
182 ꢀC) and the methiodide salt 11a from EtOH (mp
253–254 ꢀC).
maintained at an appropriate temperature (see below)
and aerated with 5% CO2–95% O2. Dose–response
curves were constructed by cumulative addition of the
reference agonist. The concentration of agonist in the
organ bath was increased approximately 3-fold at each
step, with each addition being made only after the
response to the previous addition had attained a max-
imal level and remained steady. Following 30min of
washing, tissues were incubated with the antagonist for
30min, and a new dose–response curve to the agonist
was obtained. Contractions were recorded by means of
a force displacement transducer connected to the
MacLab system PowerLab/800. In addition parallel
experiments in which tissues did not receive any
antagonist were run in order to check any variation in
sensitivity.
(cis,cis)-2-(2,2 - Diphenyl - ethyl) - 5 - methyl - hexahydro-
[1,3]dioxolo[4,5-c]pyridine oxalate (12) and methiodide
salt (12a). 12 was prepared as described for 9 starting
from 23 (1.25 g, 3.28 mmol): 0.8 g (76% yield); mp 81–
82 ꢀC; 1H NMR (CDCl3) d 1.88–2.81 (m, 8, CCH2C and
CH2CH2NCH2), 2.28 (s, 3, CH3), 3.92–4.14 (m, 2,
OCHCHO), 4.24 (t, 1, CHAr), 4.79 (t, 1, OCHO), 7.12–
7.40(m, 10, ArH).
The oxalate 12 was crystallized from EtOH (mp 184–
186 ꢀC) and the methiodide salt 12a from EtOH (mp
210–211 ꢀC).
(cis,trans)-2-(2,2-Diphenyl-ethyl)-5-methyl-hexahydro-
[1,3]dioxolo[4,5-c]pyridine oxalate (13) and methiodide
salt (13a). 13 was prepared as described for 9 starting
from 22 (0.6 g, 1.57 mmol): 0.4 g (78% yield); mp 63–
64 ꢀC; 1H NMR (CDCl3) d 1.86–2.74 (m, 8, CCH2C and
CH2CH2NCH2), 2.29 (s, 3, CH3), 4.04–4.31 (m, 3,
OCHCHO and CHAr), 5.11 (t, 1, OCHO), 7.08–7.34
(m, 10, ArH).
Guinea-pig ileum. Two-centimeter-long portions of
terminal ileum were taken at about 5 cm from the
ileum–caecum junction. The tissue was cleaned and the
ileum longitudinal muscle was separated from the
underlying circular muscle, and mounted in PSS, at
37 ꢀC, of the following composition (mM): NaCl (118),
NaHCO3 (23.8), KCl (4.7), MgSO4.7H2O (1.18),
KH2PO4 (1.18), CaCl2 (2.52), and glucose (11.7). Ten-
sion changes were recorded isotonically. Tissues were
equilibrated for 30min, and dose–response curves to
arecaidine propargyl ester (APE) were obtained at 30-
min intervals, the first one being discarded and the sec-
ond one being taken as the control.
The oxalate 13 was crystallized from EtOH (mp 180–
181 ꢀC) and the methiodide salt 13a from EtOH (mp
192–193 ꢀC).
(cis,cis)-2-(3,3 - Diphenyl - propyl) - 5 - methyl-hexahydro-
[1,3]dioxolo[4,5-c]pyridine oxalate (14) and methiodide
salt (14a). 14 was prepared as described for 9 starting
from 25 (2.0g, 5.06 mmol): 1.4 g (82% yield); 1H NMR
Guinea-pig stimulated left atria. The heart was rapidly
removed, and the right and left atria were separately
excised. Left atria were mounted in PSS (the same used
for ileum ) at 30 ꢀC and stimulated through platinum
electrodes by square-wave pulses (1 ms, 1 Hz, 5–10V)
(Tetra Stimulus, N. Zagnoni). Inotropic activity was
recorded isometrically. Tissues were equilibrated for 2 h
and a cumulative dose–response curve to APE was
constructed.
(CDCl3)
d
1.34–2.86 (m, 10, CCH2CH2C and
CH2CH2NCH2), 2.31 (s, 3, CH3), 3.86–4.22 (m, 3,
OCHCHO and CHAr), 4.98 (t, 1, OCHO), 7.11–7.33
(m, 10, ArH).
The oxalate 14 was crystallized from EtOH (mp 172–
173 ꢀC) and the methiodide salt 14a from 2-PrOH/Et2O
(mp 97–98 ꢀC).
Guinea pig lung strip. The lungs were rapidly removed
and placed in Krebs–Henseleit buffer solution of the
following composition (nM): NaCl (118.78), KCl (4.32),
CaCl2.2H2O (2.52), MgSO4.7H2O (1.18), KH2PO4
(1.28), NaHCO3 (25), glucose (5.55). Strips of periph-
eral lung tissue, approximately 15Â2Â2 mm were cut off
a lower lobe with the longitudinal axis of the strip par-
allel to the bronchus or from the peripheral margin of
the lobe. The preparations were mounted in 20-mL
organ baths at 37 ꢀC under isotonic recording with a
preload of 0.3 g. Tissues were equilibrated for 60 min,
and dose–response curves to arecaidine propargyl ester
(APE) (0.01, 0.1, 1, 10, 100 mM) were obtained at 45-
min intervals, the first one being discarded and the sec-
ond one being taken as the control.
(cis,trans)-2-(3,3 - Diphenyl - propyl)-5-methyl-hexahydro-
[1,3]dioxolo[4,5-c]pyridine oxalate (15) and methiodide
salt (15a). 15 was prepared as described for 9 starting
from 24 (1.2 g, 3.03 mmol): 0.7 g (69% yield); 1H NMR
(CDCl3)
d
1.49–2.73 (m, 10, CCH2CH2C and
CH2CH2NCH2), 2.32 (s, 3, CH3), 3.91 (t, 1, CHAr),
4.02–4.26 (m, 2, OCHCHO), 5.31 (t, 1, OCHO), 7.11–
7.34 (m, 10, ArH).
The oxalate 15 was crystallized from EtOH/Et2O (mp
154–155 ꢀC) and the methiodide salt 15a from 2-PrOH
(mp 167–168 ꢀC).
Pharmacology
Rabbit stimulated vas deferens. This preparation was set
up according to Eltze.43 Vasa deferentia were carefully
dissected free of surrounding tissue and were divided
into four segments, two prostatic portions of 1 cm and
two epididymal portions of approximately 1.5 cm
length. The four segments were mounted in PSS with
General considerations. Male guinea pigs (200–300 g)
and male New Zealand white rabbits (3.0–3.5 kg) were
killed by cervical dislocation. The organs required were
set up rapidly under 1 g of tension in 20-mL organ
baths containing physiological salt solution (PSS)

3910
A. Piergentili et al. / Bioorg. Med. Chem. 11 (2003) 3901–3911
the following composition (mM): NaCl 118.4, KCl
(4.7), CaCl2 (2.52), MgCl2 (0.6), KH2PO4 (1.18),
NaHCO3 (25), glucose (11.1); 10À6 M yohimbine was
included to block alpha2-adrenoceptors. The solution
was maintained at 30 ꢀC and tissues were stimulated
through platinum electrodes by square-wave pulses (0.1
ms, 2 Hz, 10–15 V). Contractions were measured iso-
metrically after tissues were equilibrated for 1 h, then a
cumulative dose–response curve to pCl-McN-A-343 was
constructed.
References and Notes
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2. Felder, C. C. FASEB J. 1995, 9, 619.
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Determination of antagonist potency. To quantify
antagonist potency, pKb values were calculated from the
equation pKb=log(DRÀ1)Àlog[B], where DR is the
ratio of ED50 values of agonist after and before treat-
ment with one or two antagonist concentrations [B].44
In some cases, antagonist potency is expressed in terms
of pA2, estimated by Schild plots constrained to slope
À1.0, as required by the theory.45,46
Statistical analysis. The results are expressed as mean
ÆSEM. Student’s t-test was used to assess the
statistical significance of the difference between two
means.
11. Schulte, B.; Volz-Zang, C.; Mutschler, E.; Horne, C.;
Palm, D.; Wellstein, A.; Pitschner, H. F. Clin. Pharmacol.
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Analysis of Reported Compounds
Compd Formula
Calculated
Found
14. van Noord, J. A.; Bantje, T. A.; Eland, M. E.; Korducki,
L.; Cornelissen, P. J. Thorax 2000, 55, 289.
C% H% N% C% H% N%
.
3
3a
4
4a
5
5a
6
6a
7
7a
8
8a
9
9a
10
10a
11
11a
12
12a
13
13a
14
14a
15
15a
C19H21NO2 H2C2O4 65.44 6.02 3.63 65.31 6.25 3.71
C20H24INO2 54.93 5.53 3.2054.82 5.72 3.45
C19H21NO2 H2C2O4 65.44 6.02 3.63 65.12 6.12 3.52
C20H24INO2 54.93 5.53 3.2055.13 5.85 3.12
C20H23NO2 H2C2O4 66.15 6.31 3.51 66.33 6.11 3.15
C21H26INO2 55.88 5.81 3.1055.63 5.63 2.98
C20H23NO2 H2C2O4 66.15 6.31 3.51 65.89 6.42 3.33
C21H26INO2 55.88 5.81 3.1055.52 5.53 2.88
C21H25NO2 H2C2O4 66.81 6.58 3.39 66.67 6.29 3.13
C22H28INO2 56.78 6.06 3.01 56.89 5.87 2.79
C21H25NO2 H2C2O4 66.81 6.58 3.39 67.13 6.85 3.59
C22H28INO2 56.78 6.06 3.01 56.66 5.85 3.25
C19H21NO2 H2C2O4 65.44 6.02 3.63 65.55 6.35 3.44
C20H24INO2 54.93 5.53 3.2054.83 5.45 31.0
C20H23NO2 H2C2O4 66.15 6.31 3.51 65.87 6.04 3.33
C21H26INO2 55.88 5.81 3.1056.11 5.65 2.89
C20H23NO2 H2C2O4 66.15 6.31 3.51 65.98 6.12 3.27
C21H26INO2 55.88 5.81 3.1055.66 5.59 3.39
C21H25NO2 H2C2O4 66.81 6.58 3.39 66.78 6.28 3.11
C22H28INO2 56.78 6.06 3.01 56.98 6.41 3.35
C21H25NO2 H2C2O4 66.81 6.58 3.39 66.91 6.43 3.15
C22H28INO2 56.78 6.06 3.01 56.61 5.88 2.98
C22H27NO2 H2C2O4 67.43 6.84 3.28 67.72 6.58 3.02
C23H30INO2 57.62 6.31 2.92 57.75 6.62 3.11
C22H27NO2 H2C2O4 67.43 6.84 3.28 67.16 7.03 3.45
C23H30INO2 57.62 6.31 2.92 57.43 6.02 2.81
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