Synthesis of (1S,2R)-1-phenyl-2-[(S)-1-aminoalkyl]-N,N-diethylcyclopropanecarboxamides as novel NMDA receptor antagonists having a unique NMDA receptor subtype selectivity

Article abstract of DOI:10.1039/b111540p

(1S,2R)-1-Phenyl-2-[(S)-1-aminopropyl]-N,N-diethylcyclopropanecarboxamide (2b), which is a conformationally restricted analog of the antidepressant milnacipran [(±)-1], is a new class of potent NMDA (N-methyl-D-aspartic acid) receptor antagonists. A serie

Full text of DOI:10.1039/b111540p

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Synthesis of (1S,2R)-1-phenyl-2-[(S)-1-aminoalkyl]-N,N-
diethylcyclopropanecarboxamides as novel NMDA receptor
antagonists having a unique NMDA receptor subtype selectivity
1
Yuji Kazuta,a Ryuichi Tsujita,b Shigeo Uchino,c Noriko Kamiyama,a Daisuke Mochizuki,b
Kanako Yamashita,b Yutaka Ohmori,b Akitake Yamashita,b Tamotsu Yamamoto,b
Shinich Kohsaka,c Akira Matsudaa and Satoshi Shuto*a
a Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku,
Sapporo 060-0812, Japan. E-mail: shu@pharm.hokudai.ac.jp; Fax: ϩ81117064980;
Tel: ϩ8111 7063229
b Institute of Life Science Research, Asahi Chemical Co., Ltd., Ohito-cho, Shizuoka 410-23,
Japan
c Department of Neurochemistry, National Institute of Neuroscience, 4-1-1 Ogawahigashi,
Kodaira, Tokyo 187-8502, Japan
Received (in Cambridge, UK) 18th December 2001, Accepted 8th March 2002
First published as an Advance Article on the web 4th April 2002
(1S,2R)-1-Phenyl-2-[(S)-1-aminopropyl]-N,N-diethylcyclopropanecarboxamide (2b), which is a conformationally
restricted analog of the antidepressant milnacipran [( )-1], is a new class of potent NMDA (N-methyl--aspartic
acid) receptor antagonists. A series of analogs of 2b modified at the 1Ј-position were designed and synthesized
starting from (R)-epichlorohydrin via the key intermediate an optically active cyclopropanecarbaldehyde
derivative 8 with a (1S,2R)-configuration. Among these analogs, (1S,2R)-1-phenyl-2-[(S)-1-aminobut-3-enyl]-
N,N-diethylcyclopropanecarboxamide (2i) and (1S,2R)-1-phenyl-2-[(S)-1-aminobut-3-ynyl]-N,N-diethylcyclo-
propanecarboxamide (2j) were identified as more potent NMDA receptor antagonists than 2b. The subtype
selectivity of 2i and 2j together with 2b was investigated to show that 2i inhibited the GluRε3/ζl and GluRε4/ζl
subtypes four times more strongly than GluRε1/ζl and GluRε2/ζl subtypes. Compound 2i is the first GluRε3/ζl
and GluRε4/ζl subtype-selective antagonist, while the selectivity is not so high.
the glycine binding site. Mammalian NMDA receptors are
Introduction
heterooligomeric combinations of GluRζ subunits and at least
one of four GluRε subunits (GluRε1–4).1,2 Studies on subtype
selectivity of the NMDA receptor antagonists have been
reported.7 Competitive antagonists, such as (R)-AP5 or (R)-
CPP-ene, the non-competitive channel blocker MK-801,7a and
the polyamine spider toxin argiotoxin7b somewhat selectively
antagonize the GluRε1/ζl (NR1/2A) and/or GluRε2/ζl (NR1/
2B) subtypes,7c while the channel blockers phencyclidine (PCP),
ketamine or SKF-10047 do not show any apparent subtype
selectivity.7a The glycine site antagonist 7-chlorokynurenic
acid inhibits the NMDA receptor subtypes in the order of
GluRε3/ζl (NR1/2C) > GluRε2/ζl > GluRε1/ζl > GluRε4/ζl
(NR1/2D).7d,e In recent years, ifenprodil7i and its analogs, such
as CP-101,606,7j–l have been identified as highly GluRε2/ζl
subtype-selective antagonists.
Subtype-selective NMDA receptor antagonists may retain
therapeutic activity without the side effects observed in the
previous antagonists.7j–l Thus, development of novel antagonists
with a subtype selectivity different from those of previous an-
tagonists showing serious neuronal side effects, may be desired.
The subtype selective antagonists should also be useful as tools
for pharmacological studies on the NMDA receptors.
The excitatory neurotransmitter -glutamic acid (glutamate)
has been shown to cause neuronal death in instances of stroke,
ischaemia, and head trauma.1 Glutamate receptor overstim-
ulation may also play a role in chronic neurodegenerative con-
ditions, such as Alzheimer’s disease and Parkinson’s disease.1,2
A number of studies strongly suggest that the toxicity of high
levels of glutamate is mediated primarily by NMDA (N-methyl-
-aspartic acid) receptors, one of the ionotropic glutamate
receptor (iGluR) subclasses.3 There have been attempts to
develop novel agents that block the activation of NMDA recep-
tors by glutamate or related excitatory neurotransmitters, and
a large number of competitive and non-competitive NMDA
receptor antagonists have been developed.1–3 Several of their
structures are shown in Fig. 1. A number of studies have indi-
cated that these competitive and noncompetitive antagonists
are effective in experimental models of epilepsy and stroke.1–3
However, clinical studies of these NMDA receptor antagonists
have not been as successful.1–3 Non-competitive inhibitors, such
as channel blocker MK-801, have had serious behavioral
effects4 and have caused neuronal vacuolization5 while com-
petitive inhibitors were often inactive in vivo because of poor
transport to the brain.6 Consequently, the development of
another type of efficient NMDA receptor antagonist for use in
the treatment of epilepsy, stroke, Huntington’s and/or Parkin-
son’s diseases is not only strongly required but also eagerly
desired.
( )-(Z)-2-Aminomethyl-1-phenyl-N,N-diethylcyclopropane-
carboxamide [milnacipran, ( )-1],9 a clinically effective anti-
depressant due to competitive inhibition of the re-uptake of
serotonin (5-HT) in the CNS,10 is also recognized as a non-
competitive NMDA receptor antagonist.11 Although the bind-
ing affinity of ( )-1 to the NMDA receptor is not high enough,
it may be a useful starting point in the development of an
efficient NMDA receptor antagonist, since structurally it is
It is known that NMDA receptors are composed of GluRε
(NR2) and GluRζ (NR1) subunits.7,8 The GluRε subunit con-
tains the glutamate binding site, while the GluRζ subunit bears
DOI: 10.1039/b111540p
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
This journal is © The Royal Society of Chemistry 2002
1199

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Fig. 2 Milnacipran and the previously synthesized conformationally
restricted analogs.
Fig. 1 Known NMDA receptor antagonists.
nificantly accelerated under outward current conditions in the
voltage-clamp experiments.12f These results, together with the
structural features of 2b, that are clearly different from those
of the previous antagonists, suggest that 2b is a new class of
NMDA receptor antagonist.
The above findings prompted us to carry out further studies,
which we report herein. We designed and synthesized the
additional conformationally restricted analogs 2g–m, which
have a sterically small carbon substituent at the 1Ј-position,
with the same configuration as that for 2b. The N-methyl
analog 4 and cyclic amine analogs 5–7, the structures of which
are shown in Fig. 3, were also synthesized. Among the newly
synthesized compounds, 1-phenyl-2-[(S)-1-aminobut-3-enyl]-
N,N-diethylcyclopropanecarboxamide (2i) and 1-phenyl-2-[(S)-
1-aminobut-3-ynyl]-N,N-diethylcyclopropanecarboxamide (2j)
clearly different from the known antagonists that show serious
side-effects, and it has been shown in clinical studies that
it can be transported to the brain.10d,e We previously reported
the design and synthesis of four types of conformationally
restricted analogs of ( )-1 with different stereochemistries; i.e.,
2 (Type-1) and 3 (Type-2) and their enantiomers ent-2 (Type-3)
and ent-3 (Type-4), as shown in Fig. 2. In these conformation-
ally restricted analogs, the conformation can be limited by an
alkyl group introduced at the α-position of the amino function
of ( )-1, which is essential for binding to the NMDA receptor,11
due to steric repulsion with the diethylcarbamoyl group.12a
The biological evaluation of these conformationally
restricted analogs of milnacipran showed: 1) that the conform-
ational restriction can improve the activity;12d 2) that the
analogs with a (1S,2R,1ЈS)-configuration (Type-1) are more
potent than the analogs with the other configurations (Type-2,
Type-3, and Type-4) and 3) that introduction of a substituent
bulkier than an ethyl group, such as a propyl or isobutyl group,
at the 1Ј-position significantly reduces the activity.12d Thus, we
found that analogs with a Type-1 configuration, i.e., 2a, 2b, 2c
and 2d, (Fig. 2) were efficient NMDA receptor antagonists,
significantly inhibiting the binding of [3H]MK-801, with IC50
values about 30-fold stronger than that of ( )-1.12e,f These pre-
vious studies suggested that 2b was likely to be the most desir-
able, since it was a potent NMDA receptor antagonist virtually
devoid of the inhibitory effect on 5-HT-uptake, while 2a, 2c and
2e are strong 5-HT-uptake inhibitors like the parent compound
milnacipran.12h Pharmacological studies on 2b have shown: 1)
that 2b binds to the receptor in an agonist-independent manner,
whereas the binding affinities of known non-competitive
NMDA receptor antagonists are affected by agonist concen-
tration;12h and 2) that the release of 2b and the previous non-
competitive antagonists, such as MK-801, from their binding
sites was quite different with respect to their dependence on the
direction of ionic currents flowing through the channel pores
of NMDA receptors, i.e., outward currents had no effect on
the channel block of 2b, while the release of MK-801 was sig-
Fig. 3 The newly designed conformationally restricted analogs of
milnacipran.
1200
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Scheme 1 Reagents: (a) RMgBr, THF; (b) NaN3, PPh3, CBr4, DMF; (c) H2, Pd–C, MeOH; (d) TFA, CH2Cl2–H2O; (e) 1) H2, Pd–C, MeOH, 2)
molecular sieves 5 Å, CH2Cl2; (f ) NaBH3CN, MeOH.
were identified as the most potent compounds in this series of
NMDA receptor antagonists. The subtype selectivity of 2i and
2j together with 2b was also investigated to show that 2i is the
first GluRε3/GluRζl and GluRε4/GluRζl subtypes-selective
antagonist, though the subtype selectivity is not so high.
major product 12S from 10 was confirmed as S based on the
signals of the three protons observed separately at δ 1.92, 1.01
and 1.63 respectively, as shown in Table 1.
After acidic treatment of 12S, the resulting aldehyde 14 was
treated with H2/Pd–C in MeOH and then with molecular sieves
(5 Å in CH2Cl2) causing spontaneous cyclization giving the
desired 1ЈS-cyclic-imino derivative 6. Further reduction of
the imino moiety of 6 with NaBH3CN in MeOH furnished the
corresponding pyrrolidine derivative 7.
Results and discussion
Synthesis of 2b derivatives
Treatment of the 1Ј-cyclopropyl derivative 9 with the NaN3–
PPh3–CBr4 system, similar to that for 10 described above,
unexpectedly gave the configuration-inverted 1ЈR-azide 11R,
and not the desired 1ЈS-product 11S. The 1ЈR-configuration
was suggested by the 1H NMR chemical shifts shown in Table 1
and was further confirmed by the X-ray crystallographic
analysis of the corresponding amine 15 derived from 11R. The
stereochemical result showed that the nucleophilic substitution
between an azide anion and the carbocation generated from 9
did not proceed via the neighboring group participation inter-
mediate II (Scheme 1). It has been recognized that cyclo-
propylmethyl carbocations can be significantly stabilized by the
interaction between a vacant p-orbital on the carbocation and
electrons of the cyclopropane ring, which are characterized as
strong π-donors.14 Therefore, the reaction was likely to proceed
via an SN1 reaction pathway due to highly effective stabilization
of the 1Ј-carbocation by the adjacent two cyclopropane rings.
The reaction gave stereoselectively the undesired 1ЈR-azide 11b,
since, with regard to the intermediate carbocation, a con-
formation of the bisected s-trans-form would be preferred over
the bisected s-cis-form due to steric repulsion between the
1Ј-cyclopropyl group and the N,N-diethylcarbamoyl group.
Therefore an azide anion would attack the intermediate from
the less-hindered face forming the undesired product 11b, as
shown in Scheme 2. Catalytic hydrogenation of 11R with Pd–C
in MeOH gave 1ЈR-cyclopropylamine 15, the X-ray crystallo-
graphic structure of which is shown in Fig. 4. Consequently, the
synthesis of the 1ЈS-cyclopropyl analog 2h was unsuccessful.
The syntheses of the analogs 2i–l and 5, having allyl, prop-
argyl†, 2-hydroxyethyl, 2-methoxyethyl, or azetidinyl substi-
tuents at the 1Ј-position, are shown in Scheme 3. All of these
compounds were synthesized from the (1ЈS)-1Ј-azido-1Ј-(2-
pivaloyloxyethyl) derivative 16, which was prepared from 8
All of the target compounds were synthesized from an optically
active cyclopropanecarbaldehyde derivative 8 with a (1S,2R)-
configuration, which was prepared from (R)-epichlorohydrin
according to a previously reported method.12a
Syntheses of the 1Ј-cyclopropyl, -pyrrolinyl and -pyrrol-
idinyl analogs (2h, 6 and 7, respectively) were undertaken via
Grignard reactions of 8 (Scheme 1). Thus, reaction of 8 with
cyclopropyl- or 3,3-dimethoxypropylmagnesium bromide in
THF was performed to give the corresponding 1ЈS-products 9
and 10 with high diastereoselectivity in 79% and 96% yields,
respectively. We previously showed that the addition reaction of
Grignard reagents to 8 proceeds from the least-hindered si-face
in the bisected s-trans conformation I, which would be preferred
due to the peculiar stereo-electronic effect of the cyclopropane
ring, to produce 1ЈS-addition products highly stereo-
selectively.12a,b Treatment of 10 with the NaN3–PPh3–CBr4
system13 gave the 1ЈS-azide 12S as the major product in 49%
yield along with the 1ЈR-diastereomer 12R in 15% yield. We
have demonstrated that this reaction occurs via the neighboring
group participation intermediate II to give the corresponding
configuration-retained azidomethylcyclopropane derivatives as
the major products.12a,d,e The 1Ј-configurations of 12S and 12R
1
were further supported by the chemical shifts in the H NMR
spectra as summarized in Table 1. We observed that a series of
the 1Ј-azido-cyclopropane derivatives show a typical chemical
shift pattern depending on the 1Ј-configuration. Table 1 shows
1
the H NMR spectral data of the previously synthesized 1ЈR-
azides 29R12a and 30R,12a and 1ЈS-azides 29S,12a 30S,12a 31S12d
and 32S,12d the stereochemistries of which were determined
earlier. The 1H NMR data of 1ЈS-azides 16–19, the stereo-
chemistries of which were confirmed as described below, are
also summarized in Table 1. In the 1ЈS-azide series, the H-2,
H-3a and H-3b signals are separately observed around δ 1.9, 1.0
and 1.6 respectively, while the three proton signals overlap in
the spectra of the 1ЈR-azides. Thus the 1Ј-configuration of the
† The IUPAC name for propargyl is prop-2-ynyl.
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
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Table 1 1H NMR chemical shifts of the 1Ј-azide derivatives in CDCl3
Chemical shift, δ (multiplicity)
Compd
R
1Ј-Config.
H-1Ј
H-2
H-3a
H-3b
29S
30S
31S
32S
12S
16
Me
Et
Pr
i-Bu
S
S
S
S
S
S
S
S
S
S
R
R
R
R
R
2.98–3.08 (m)
2.86 (ddd)
2.90 (ddd)
2.92 (ddd)
2.97 (m)
1.95 (ddd)
1.96 (ddd)
1.96 (ddd)
1.96 (ddd)
1.92 (ddd)
1.92 (ddd)
1.89 (ddd)
1.68 (ddd)
1.87–1.98 (m)
1.74–1.85 (m)
1.48–1.52 (m)
1.47–1.60 (m)
1.62–1.69 (m)
1.48 (ddd)
0.91 (dd)
0.95 (dd)
0.94 (dd)
0.95 (dd)
1.01 (dd)
1.06 (dd)
1.12 (dd)
1.10 (dd)
1.02 (dd)
1.20 (dd)
1.48–1.52 (m)
1.47–1.60 (m)
1.42 (dd)
1.56–1.65 (m)
1.48–1.52 (m)
1.61 (dd)
1.65 (dd)
1.66 (dd)
1.65 (dd)
1.63 (dd)
1.59 (dd)
1.58 (dd)
1.41 (dd)
1.62 (dd)
1.57 (dd)
1.48–1.52 (m)
1.47–1.60 (m)
1.62–1.69 (m)
1.56–165 (m)
1.48–1.52 (m)
(MeO)2CH2CH2CH2
PvOCH2CH2
HOCH2CH2
TsOCH2CH2
MeOCH2CH2
N3CH2CH2
Me
3.14 (m)
17
3.18–3.29 (m)
3.19–3.26 (m)
3.13–3.23 (m)
3.17 (m)
3.33–3.38 (m)
3.12–3.26 (m)
3.27–3.35 (m)
3.33 (m)
18
19
27S
29R
30R
11R
12R
27R
Et
Cyclopropyl
(MeO)2CH2CH2CH2
N3CH2CH2
3.38–3.52 (m)
1.48 (ddd)
corresponding amines 2k and 2l, respectively. After treat-
ment of 17 with TsCl–Et3N–DMAP, the resulting tosyloxy
derivative19 was hydrogenated with Pd–C in MeOH to cause
spontaneous cyclization giving the azetidine derivative 5.
Hydrogenation of 16 with Pd–C in the presence of Boc2O gave
the Boc-protected amine 20, which was treated with NaOMe–
MeOH to afford the 1Ј-(2-hydroxyethyl) derivative 21. Wittig
reaction of the aldehyde 22, which was prepared by Swern
oxidation of 21, with Ph P᎐CH produced the corresponding
᎐
3
2
1Ј-allyl derivative 23. The corresponding dibromo derivative
24 was obtained by a similar Wittig-type reaction of 22 with
a CBr4–PPh3 system, and subsequent treatment of 24 with
BuLi15 gave the propargyl derivative 25. Removal of the Boc
group of 23 and 25 under acidic conditions furnished 2i and 2j.
The 1Ј-(2-aminoethyl) derivative 2m and the N-methylated
analog 4 were prepared readily by the usual chemistry as sum-
marized in Schemes 4 and 5.
Scheme 2 A possible reaction mechanism for the formation of 11b via
a SN2 reaction pathway.
Affinity for the NMDA receptor of rat cerebral cortex
The synthesized compounds were evaluated for their binding
affinity to the NMDA receptor of cerebral cortical synaptic
membranes from rats with [3H]MK-801 as a radioligand.16
The results, together with those of several previously reported
compounds,12d,e are shown in Table 2.
The binding affinity was significantly affected by the sub-
stituent at the 1Ј-position. Compounds 2e, 2k, 2l and 2m, in
which a proton at the terminal carbon of the 1Ј-ethyl group of
2b is replaced with a methyl, hydroxy, methoxy, or an amino
group, showed binding affinities with IC50 values between
1.0–2.0 µM, i.e. weaker than for 2b (IC50 = 0.20 0.02 µM).
Branching in the 1Ј-substituent, such as the isopropyl derivative
2g as well as the previously reported isobutyl derivative 2f,12d
significantly decreased the activity.
It is worth noting that introduction of an unsaturated bond
at the terminal carbon of the 1Ј-ethyl group of 2b improved the
binding affinity; the 1Ј-allyl analog 2i and the 1Ј-propargyl
analog 2j significantly inhibited the binding of [3H]MK-801
with IC50 values of 0.12 0.008 and 0.10 0.03 µM, respect-
ively, which are the strongest binding affinities in the com-
pounds synthesized so far.
Fig. 4 X-Ray crystallographic structure of 15.
according to the previous method.12d Removal of the pivaloyl
group of 16 gave the 1Ј-hydroxyethyl derivative 17, which after
treatment with MeI–NaH gave the corresponding O-methyl
derivative 18. The usual hydrogenation of 17 and 18 gave the
1202
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Scheme 3 Reagents: (a) NaOMe, MeOH; (b) MeI, NaH, THF; (c) TsCl, Et3N, DMAP, CH2Cl2; (d) H2, Pd–C, MeOH; (e) H2, Pd–C, Boc2O, MeOH;
(f ) DMSO, (COCl)2, Et3N, CH2Cl2; (g) Ph3P᎐CH2, THF; (h) HCl, aq. MeOH; (i) CBr4, PPh3, CH2Cl2; j) BuLi, THF.
᎐
2.6 µM), which suggested that the presence of a proton on the
1Ј-amino nitrogen would be important for the binding.
Inhibition of the 5-HT-uptake
The inhibitory effects of the compounds on the uptake of 5-HT
by nerve terminals of the cerebral cortical synaptic membrane
from rats were next evaluated with [3H]paroxetine as a radio-
ligand,12d since milnacipran [( )-1], the parent compound, is a
potent inhibitor of 5-HT uptake.10 The results are also summar-
ized in Table 2. All of the newly synthesized compounds (2i–l
and 4–7), except the 1Ј-isopropyl derivative 2g and the 1Ј-(2-
aminoethyl) derivative 2m, showed no appreciable effect on the
uptake of 5-HT. From these results, it appears that the inhib-
itory potency of the conformationally restricted analogs with
Type-1 configuration against the 5-HT uptake is significantly
affected by the bulkiness of the 1Ј-substituent (Me, CH᎐CH >
᎐
2
᎐
C᎐CH ӷ Et, Pr, etc.). It is important that, although the 1Ј-
᎐
Scheme 4 Reagents: (a) NaN3, PPh3, CBr4, HMPA; (b) H2, Pd–C,
MeOH.
ethenyl and -ethynyl derivatives (2c and 2e) have a significant
inhibitory effect, their homologs, the 1Ј-allyl derivative 2i and
the 1Ј-propargyl derivative 2j, are virtually inactive as 5-HT
uptake inhibitors. In particular, the 1Ј-allyl derivative 2i showed
a remarkable selectivity index [5-HT uptake (Ki)/NMDA recep-
tor binding (IC50)] of >830, which is clearly superior to that of
2b (selectivity index = 120).
NMDA receptor subtype selectivity
We have established Chinese hamster ovary (CHO) cell lines
carrying NMDA receptor subtype cDNAs (i.e., GluRζ1 and
each of GluRε1, GluRε2, GluRε3, or GluRε4) under the
control of the Drosophila hsp70 promoter.17 Heat treatment of
the cell lines by incubation at 43 ЊC for 30–60 min induced the
functional expression of NMDA receptor subtypes, since the
heat-treated cells showed robust responses to co-application of
30 µM -glutamate and 30 µM glycine, as shown by an increase
in the intracellular Ca2ϩ concentration ([Ca2ϩ]i). Thus, using
these clonal cell lines and calcium fluorometry, we determined
the antagonistic potency and subtype selectivity of NMDA
receptor antagonists.
Scheme 5 Reagents: (a) Boc2O, Et3N, CH2Cl2; (b) MeI, BuLi, THF;
(c) HCl, aq. MeOH.
Although the cyclic amine derivatives 5 and 7 showed rather
potent binding affinities for the receptor (IC50 values of 0.62
0.01 and 1.0 0.2 µM, respectively), they were weaker than for
2b. The pyrroline derivative 6 was almost inactive (IC50 = 13
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
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Table 2 Effects of the compounds on NMDA receptor binding and 5-HT-uptake
NMDA receptor bindinga
(IC50/µM)
5-HT-uptakeb
(Ki/µM)
Selectivity indexc
(5-HT/NMDA)
Compd
X
R
( )-1
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
H
Me
Et
6.3 0.3
0.35 0.08
0.20 0.02
0.16 0.02
0.29 0.2
1.0 0.05
4.2 0.2
0.0085 0.0006
0.014 0.002
24 0.9
0.023 0.0007
0.19 0.2
0.0013
0.040
120
0.14
0.66
37
> 24
0.26
> 830
200
2a
2b
2c
CH᎐CH2
᎐
᎐
2d
C᎐CH
᎐
2e
Pr
37
> 100
4.4 0.1c
> 100
20
24
> 100
3
2f
i-Bu
i-Pr
CH2CH᎐CH2
2g
17 0.9
2i
2j
0.12 0.008
0.10 0.03
1.2 0.02
1.7 0.4
1.4 0.2
0.37 0.0
0.62 0.01
᎐
᎐
CH2C᎐CH
1
1
᎐
2k
CH2CH2OH
CH2CH2OMe
CH2CH2NH2
Et
20
2l
> 59
0.34
81
52
1.5
2m
NH2
0.48 0.002
30 0.2
4
NHMe
Azetidin-2-yl
Pyrrolin-5-yl
Pyrrolidin-2-yl
5
32
20
2
1
6
13
3
7
1.0 0.2
0.61 0.46
0.0098 0.005
32 0.5
32
Ketamine
PCP
a Assay was performed with cerebral cortical synaptic membrane of rats using [3H]MK-801 (n = 2; , standard error). b Assay was performed with
cerebral cortical synaptic membrane of rats using [3H]paroxetine (n = 2; , standard error). c The ratio: 5-HT uptake inhibition (Ki) : NMDA receptor
binding (IC50).
Table 3 Effects of PPDC, 2i, and 2j on GluRε1/ζ1, GluRε2/ζ1, GluRε3/ζ1 and GluRε4/ζ1 subtypes
IC50/µMa (Hill coefficient)
Compd
GluRε1/ζ1
GluRε2/ζ1
GluRε3/ζ1
GluRε4/ζ1
PPDC (2b)
41.7 1.5
(0.9 0.1)
13.3 0.5
(1.1 0.1)
12.6 0.5
(1.0 0.1)
11.5 1.2
(1.0 0.1)
2i
43.0 3.9
(1.2 0.1)
37.9 3.0
(1.2 0.1)
10.6 1.1
(1.2 0.1)
9.8 0.6
(1.1 0.1)
2j
36.4 2.2
(1.1 0.2)
12.3 1.0
(1.1 0.04)
14.5 1.8
(1.0 0.02)
14.1 1.1
(1.0 0.04)
( )-AP5
Ifenprodil
0.88 0.03
(1.2 0.04)
1.45 0.10
(1.0 0.1)
2.39 0.03
(1.2 0.1)
17.5 1.5
(0.8 0.03)
>100
0.35 0.03
(2.0 0.2)
>100
>100
a Assay was performed with the CHO cell lines carrying NMDA receptor subtype cDNAs (n = 3; , standard error).
We initially tested the sensitivity of the four NMDA receptor
subtypes to two well-characterized NMDA receptor antagon-
ists, ( )-AP5 and ifenprodil. The values were obtained by the
three independent experiments and are shown in Table 3. The
four NMDA receptor subtypes showed differential sensitivity
to ( )-AP5. The IC50 values of ( )-AP5 were 0.88 0.03 µM for
GluRε1/ζ1, 1.45 0.10 µM for GluRε2/ζ1, 2.39 0.03 µM for
GluRε3/ζ1 and 17.5 1.48 µM for GluRε4/ζ1. The observed
rank order is in accordance with that found in the Xenopus
oocytes expression system.7i Ifenprodil is a GluRε2/ζ1 subtype
selective antagonist acting at the polyamine modulatory site.7l,m
As expected, the GluRε2/ζ1 subtype was highly sensitive to
ifenprodil, whereas concentrations of greater than 100 µM were
required to affect the responses to other receptor subtypes. The
IC50 value of 0.35 0.03 µM (Hill coefficient = 2.0 0.2) was
similar to that obtained using GluRε2/ζ1 expressed in the
Xenopus oocytes (0.34 µM) reported previously.7m These results
indicate that the established clonal cell lines are useful in char-
acterizing the pharmacological properties of drugs that act on
NMDA receptors.
We next determined the antagonistic potency of 1Ј-ethyl
derivative 2b, 1Ј-allyl derivative 2i, and 1Ј-propargyl derivative
2j to the subtypes. The results obtained by the three independ-
ent experiments, and the IC50 values are summarized in Table 3.
Fig. 5 clearly shows that the NMDA receptor subtype carry-
ing CHO cell lines are very effective for the subtype selec-
tivity evaluation of the compounds. Thus, we determined the
antagonistic potency and subtype selectivity of the novel
antagonists 2b, 2j and 2i. The compounds 2b and 2j were similar
in effect for the four NMDA receptor subtypes, the rank-order
of sensitivity being GluRε2/ζ1 ≈ GluRε3/ζ1 ≈ GluRε4/ζ1 >
GluRε1/ζ1. In contrast, compound 2i inhibits the GluRε3/ζl
and/or GluRε4/ζl subtypes four times more strongly than
GluRε1/ζl and/or GluRε2/ζl subtypes. This difference in sensi-
tivity of the compounds provide new insights into development
of subtype-selective drugs.
1204
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212

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especially psychotomimetic effects and motor impairment.4,5
The availability of subtype-selective drugs may minimize the
adverse side effects of NMDA receptor antagonists. In fact,
the GluRε2 subunit-selective antagonist, CP-101606 and its
derivatives suppress mechanical hyperalgesia and inhibit
capsaicin- and 4β-phorbol-12-myristate-12-acetate-induced
nociceptive responses without producing any behavioural side
effects.7j,k
As described above, the studies on subtype selectivity of the
NMDA receptor antagonists have shown that the previous
antagonists were nonselective or selective to the GluRε1/ζl,
GluRε2/ζl and/or GluRε3/ζl subtypes.7 The present study
showed that 2b and 2j are selective to GluRε2/ζ1, GluRε3/ζ1
and GluRε4/ζ1 subtypes and that 2i is selective to GluRε3/ζ1
and GluRε4/ζ1 subtypes, although the selectivity is not so high.
The compounds 2b, 2i and 2j proved to be a new class of
NMDA receptor antagonist from the viewpoint of subtype
selectivity.
Conclusion
We designed a series of conformationally restricted analogs of
milnacipran [( )-1], which was efficiently synthesized starting
from (R)-epichlorohydrin. Among the compounds studied, 2i
and 2j were identified as a new class of the potent NMDA
receptor antagonists, which have subtype selectivity different
from those of previous antagonists. These results proved that
our conformational restriction strategy using the structural
feature of the cyclopropane ring is very effective.
Experimental
Melting points were determined on a Yanagimoto MP-3 micro-
melting point apparatus and are uncorrected. The NMR spectra
were recorded with a JEOL EX-400 or Bruker AMX 500
spectrometer with tetramethylsilane as an internal standard.
Chemical shifts were reported in parts per million (δ), and sig-
nals are expressed as s (singlet), d (doublet), t (triplet), q (quar-
tet), m (multiplet), or br (broad). Mass spectra were measured
on a JEOL JMS-D300 spectrometer. Specific optical rotations
were measured on a JASCO DIP-370 in 10Ϫ1 deg cm2 gϪ1. Thin-
layer chromatography was done on Merck silica gel coated
plates (60F254). Silica gel chromatography was done with Merck
silica gel 5715. Reactions were performed under argon.
(1S,2R)-1-Phenyl-2-[(S)-cyclopropylhydroxymethyl]-N,N-
diethylcyclopropanecarboxamide 9
To a suspension of Mg turnings (1.31 g, 54.0 mmol) in THF
(10 mL) was added a solution of cyclopropyl bromide (4.30
mL, 54.0 mmol) in THF (60 mL), and the mixture was stirred at
room temperature for 2 h. To the resulting solution was added
slowly a solution of 8 (4.41 g, 18.0 mmol) in THF (180 mL) at
Ϫ20 ЊC. The mixture was stirred at the same temperature for
2.5 h and was quenched with saturated aqueous NH4Cl. The
resulting mixture was concentrated in vacuo (for removal of
THF), and then partitioned between AcOEt and H2O. The
organic layer was washed with brine, dried (Na2SO4), and evap-
orated. The residue was purified by column chromatography
(silica gel, Et2O–hexane, 1 : 3) to give 9 as white crystals (4.09 g,
79%): mp (AcOEt–hexane) 70–72 ЊC; [α]2D6 Ϫ50.6 (c 0.990,
Fig. 5 Effects of PPDC (a), 2i (b), and 2j (c) on NMDA receptor
subtypes expressed in CHO cell lines: ᭺, GluRε1/ζ1; ꢀ, GluRε2/ζ1;
ᮀ, GluRε3/ζ1; ᭛, GluRε4/ζ1.
1
MeOH); H-NMR (500 MHz, CDCl3) δ 0.32 (1 H, m, H-3Ј),
0.41 (1 H, m, H-3Ј), 0.46–0.54 (2 H, m, H-3Ј), 0.90 (3 H, t,
–NCH2CH3, J = 7.1 Hz), 1.07 (1 H, m, H-2Ј), 1.08 (1 H, dd,
H-3a, J3a,3b = 5.4, J3a,2 = 8.7 Hz), 1.13 (3 H, t, –NCH2CH3, J =
Excessive activation of the NMDA receptor may lead to an
excessive increase in [Ca2ϩ]i followed by neurodegeneration.18
Thus, NMDA receptor antagonists would be useful in protect-
ing neurons from brain diseases, such as epilepsy, stroke,
ischaemia and Parkinson’s syndrome.1–3,19 However, NMDA
receptor antagonists may have various adverse side effects,
7.1 Hz), 1.44 (1 H, ddd, H-2, J2,3b = 6.4, J2,3a = 8.7, J2,1Ј
=
9.2 Hz), 1.73 (1 H, dd, H-3b, J3b,3a = 5.4, J3b,2 = 8.7 Hz), 2.65
(1 H, ddd, H-1Ј, J1Ј,OH = 5.4, J1Ј,2Ј = 8.7, J1Ј,2 = 9.2 Hz), 3.35 (2 H,
m, –NCH2CH3), 3.42 (1 H, m, –NCH2CH3), 3.49 (1 H, m,
–NCH2CH3), 5.32 (1 H, d, –OH, JOH,1Ј = 1.7 Hz), 7.18–7.23
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
1205

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(3 H, m, aromatic), 7.27–7.31 (2 H, m, aromatic); 13C-NMR
(125 MHz, CDCl3) δ 1.59 (C-3Јa), 2.19 (C-3Јb), 12.30
(–NCH2CH3), 13.08 (–NCH2CH3), 16.06 (C-2Ј), 17.13
(C-3), 33.18 (C-1), 36.69 (C-2), 39.40 (–NCH2CH3), 41.91
(–NCH2CH3), 77.71 (C-1Ј), 125.60 (C-2Љ and C-6Љ), 126.52
(1S,2R)-1-Phenyl-2-[(R)-amino(cyclopropyl)methyl]-N,N-
diethylcyclopropanecarboxamide hydrochloride 15
A mixture of 11R (2.50 g, 8.00 mmol) and 10% Pd–charcoal
(200 mg) in MeOH (110 mL) was stirred under atmospheric
pressure of hydrogen at room temperature for 1.5 h, and then
the catalyst was filtered off. The filtrate was evaporated, and the
residue was purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 1, then CHCl3–MeOH 9 : 1) to give the free
amine as an oil. After the oil was dissolved in MeOH, the result-
ing solution was put on a column of Diaion WA-30 resin (ClϪ
form), and the column was developed with MeOH. The solvent
of appropriate fractions was evaporated, and the residue was
treated with Et2O to give white crystals of 15 as a hydrochloride
salt (2.20 g, 85%): mp (Et2O) 172–174 ЊC; [α]2D5 ϩ11.4 (c 0.982,
(C-4Љ), 128.64 (C-3Љ and C-5Љ), 140.33 (C-1Љ), 171.39 (C᎐O);
᎐
HR-MS (EI) 287.1874 (Mϩ, C18H25NO2 requires m/z 287.1885).
Found: C, 75.11; H, 8.74; N, 4.70. C18H25NO2 requires C, 75.26;
H, 8.71; N, 4.87%.
(1S,2R)-1-Phenyl-2-[(S)-1-hydroxy-4,4-dimethoxybutyl]-N,N-
diethylcyclopropanecarboxamide 10
To a suspension of Mg turnings (680 mg, 28.0 mmol) and I2
(10 mg, 0.04 mmol) in THF (20 mL) was added a solution of
3-bromopropionaldehyde dimethyl acetal (3.82 mL, 28.0 mmol)
in THF (20 mL), and the mixture was stirred at room temper-
ature for 2 h. To the resulting solution was added slowly a sol-
ution of 8 (1.72 g, 7.00 mmol) in THF (20 mL) at Ϫ15 ЊC. The
mixture was stirred at the same temperature for 2.5 h and was
quenched with saturated aqueous NH4Cl. The resulting
mixture was concentrated in vacuo (for removal of THF), and
then partitioned between AcOEt and H2O. The organic layer
was washed with brine, dried (Na2SO4), and evaporated. The
residue was purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 4) to give 10 as an oil (2.23 g, 91%): [α]2D2
1
CHCl3); H-NMR (500 MHz, CD3OD : CDCl3, 1 : 1) δ 0.48
(1 H, m, H-3Ј), 0.59 (1 H, m, H-3Ј), 0.70–0.76 (3 H, m, H-3Ј
and H-2Ј), 0.87 (3 H, t, –NCH2CH3, J = 7.1 Hz), 1.14 (3 H, t,
–NCH2CH3, J = 7.1 Hz), 1.65 (1 H, ddd, H-2, J2,3a = 7.0, J2,3b
9.0, J2,1Ј = 9.5 Hz), 1.72 (1 H, dd, H-3a, J3a,3b = 5.8, J3a,2
9.0 Hz), 1.90 (1 H, dd, H-3b, J3b,3a = 5.8, J3b,2 = 9.0 Hz), 2.91
(1 H, dd, H-1Ј, J1Ј,2Ј = 7.0, J1Ј,2 = 9.5 Hz), 3.33–3.45 (3 H, m,
–NCH2CH3), 3.54 (1 H, m, –NCH2CH3), 7.25–7.29 (3 H, m,
aromatic), 7.34–7.37 (2 H, m, aromatic); 13C-NMR (125 MHz,
CD3OD : CDCl3, 1 : 1) δ 3.69 (C-3Јa), 4.33 (C-3Јb), 10.30
(C-2Ј), 11.71 (–NCH2CH3), 12.39 (–NCH2CH3), 16.58
(C-3), 29.84 (C-2), 33.39 (C-1), 39.85 (–NCH2CH3), 42.45
(–NCH2CH3), 56.66 (C-1Ј), 125.35 (C-2Љ and C-6Љ), 127.07
=
=
1
ϩ65.0 (c 0.635, CHCl3); H-NMR (500 MHz, CDCl3) δ 0.92
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.06 (1 H, dd, H-3a, J3a,3b
=
(C-4Љ), 128.73 (C-3Љ and C-5Љ), 138.55 (C-1Љ), 170.98 (C᎐O);
᎐
6.0, J3a,2 = 6.0 Hz), 1.14 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.27
(1 H, ddd, H-2, J2,3a = 6.0, J2,3b = 9.2, J2,1Ј = 9.2 Hz), 1.66–1.89
(5 H, m, H-3b and H-2Ј and H-3Ј), 3.16 (1 H, m, H-1Ј), 3.32
(3 H, s, –OCH3), 3.33 (3 H, s, –OCH3), 3.28–3.45 (3 H, m,
–NCH2CH3), 3.51 (1 H, m, –NCH2CH3), 4.39 (1 H, t, H-4Ј,
J4Ј,3Ј = 5.5 Hz), 5.43 (1 H, br s, –OH), 7.19–7.30 (5 H, m,
aromatic); 13C-NMR (125 MHz, CDCl3) δ 12.33 (–NCH2CH3),
13.12 (–NCH2CH3), 16.95 (C-3), 28.99 (C-3Ј), 31.05
(C-2Ј), 33.70 (C-1), 36.83 (C-2), 39.46 (–NCH2CH3), 41.95
(–NCH2CH3), 52.54 (–OCH3), 53.11 (–OCH3), 74.10 (C-1Ј),
104.81 (C-4Ј), 125.70 (C-2Љ and C-6Љ), 126.59 (C-4Љ), 128.65
HR-MS (EI) 286.2037 (Mϩ Ϫ HCl, C18H26N2O requires m/z
286.2045). Found: C, 66.84; H, 8.44; N, 8.63. C18H27ClN2O
requires C, 66.98; H, 8.37; N, 8.68%.
(1S,2R)-1-Phenyl-2-[(S)-1-azido-4,4-dimethoxybutyl]-N,N-
diethylcyclopropanecarboxamide 12S and (1S,2R)-1-phenyl-2-
[(R)-1-azido-4,4-dimethoxybutyl]-N,N-diethylcyclopropane-
carboxamide 12R
Compound 10 (699 mg, 2.00 mmol) was treated as described
above for the synthesis of 11R from 9. After purification by
column chromatography (silica gel, AcOEt–hexane, 3 : 17), 12S
as an oil (368 mg, 49%) and 12R as an oil (110 mg, 15%) were
obtained, respectively. 12S: [α]2D1 Ϫ123.3 (c 0.505, CHCl3);
1H-NMR (500 MHz, CDCl3) δ 0.39 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.01 (1 H, dd, H-3a, J3a,3b = 5.0, J3a,2 = 9.2 Hz), 1.12
(C-3Љ and C-5Љ), 140.23 (C-1Љ), 171.39 (C᎐O); LR-MS (EI) m/z
᎐
349 (Mϩ). Found: C, 68.94; H, 9.02; N, 4.21. C20H31NO4
requires C, 68.74; H, 8.94; N, 4.01%.
(1S,2R)-1-Phenyl-2-[(R)-azido(cyclopropyl)methyl]-N,N-diethyl-
cyclopropanecarboxamide 11R
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.63 (1 H, dd, H-3b, J3b,3a
=
5.0, J3b,2 = 6.7 Hz), 1.74–1.84 (4 H, m, H-2Ј and H-3Ј), 1.92
(1 H, ddd, H-2, J2,3b = 6.7, J2,3a = 9.2, J2,1Ј = 9.6 Hz), 2.97 (1 H,
m, H-1Ј), 3.04 (1 H, m, –NCH2CH3), 3.18 (1 H, m,
–NCH2CH3), 3.34 (6 H, s, –OCH3), 3.50 (1 H, m, –NCH2CH3),
3.67 (1 H, m, –NCH2CH3), 4.39 (1 H, t, H-4Ј, J4Ј,3Ј = 4.5 Hz),
7.20–7.32 (5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3)
δ 11.87 (–NCH2CH3), 12.29 (–NCH2CH3), 19.42 (C-3),
27.95 (C-2), 28.82 (C-2Ј), 30.09 (C-3Ј), 35.98 (C-1), 39.97
(–NCH2CH3), 42.05 (–NCH2CH3), 52.96 (–OCH3), 53.37
(–OCH3), 62.58 (C-1Ј), 104.18 (C-4Ј), 126.69 (C-4Љ), 126.90
(C-2Љ and C-6Љ), 128.74 (C-3Љ and C-5Љ), 140.70 (C-1Љ), 169.34
After a solution of 9 (5.74 g, 20.0 mmol), PPh3 (15.7 g, 60.0
mmol), and CBr4 (19.9 g, 60.0 mmol) in DMF (150 mL) was
stirred at 0 ЊC for 30 min, NaN3 (24.7 g, 380 mmol) was added
to the mixture. The resulting mixture was stirred at room tem-
perature for 3 h and then was quenched with H2O. The mixture
was partitioned between AcOEt and H2O, and the organic layer
was washed with brine, dried (Na2SO4), and evaporated. The
residue was purified by flash column chromatography (silica
gel, AcOEt–hexane, 1 : 14) to give 11R as an oil (2.81 g, 45%):
[α]2D6 Ϫ117.5 (c 0.984, MeOH); H-NMR (500 MHz, CDCl3)
1
δ 0.36 (1 H, m, H-3Ј), 0.44–0.57 (2 H, m, H-3Ј), 0.61 (1 H, m,
H-3Ј), 0.70 (3 H, t, –NCH2CH3, J = 7.1 Hz), 1.12 (3 H, t,
–NCH2CH3, J = 7.1 Hz), 1.26 (1 H, m, H-2Ј), 1.42 (1 H, dd,
H-3a, J3a,3b = 5.0, J3a,2 = 8.6 Hz), 1.62–1.69 (2 H, m, H-3b and
H-2), 3.19 (1 H, m, –NCH2CH3), 3.27–3.35 (2 H, m, H-1Ј and
–NCH2CH3), 3.39 (1 H, m, –NCH2CH3), 3.54 (1 H, m, –NCH2-
CH3), 7.20–7.36 (5 H, m, aromatic); 13C-NMR (125 MHz,
CDCl3) δ 2.16 (C-3Јa), 2.70 (C-3Јb), 12.42 (–NCH2CH3), 12.69
(–NCH2CH3), 15.76 (C-2Ј), 17.54 (C-3), 31.53 (C-2), 33.50
(C-1), 39.59 (–NCH2CH3), 42.09 (–NCH2CH3), 64.75 (C-1Ј),
126.22 (C-2Љ and C-6Љ), 126.57 (C-4Љ), 128.68 (C-3Љ and C-5Љ),
(C᎐O); HR-MS (EI) 374.2297 (Mϩ, C H N O requires
᎐
20 30
4
3
m/z 374.2318). Found: C, 64.39; H, 8.10; N, 14.68. C20H30N4O3
requires C, 64.15; H, 8.07; N, 14.96%. 12R: [α]2D1 Ϫ44.2 (c 0.430,
CHCl3); 1H-NMR (500 MHz, CDCl3) δ 0.67 (3 H, t,
–NCH2CH3, J = 7.0 Hz), 1.11 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.48 (1 H, m, H-2), 1.56–1.65 (2 H, m, H-3a and H-3b), 1.66–
1.75 (2 H, m, H-3Ј), 1.85 (1 H, m, H-2Јa), 2.01 (1 H, m, H-2Јb),
3.16 (1 H, m, –NCH2CH3), 3.25 (1 H, m, –NCH2CH3), 3.30
(3 H, s, –OCH3), 3.31 (3 H, s, –OCH3), 3.33 (1 H, m, H-1Ј),
3.43–3.52 (2 H, m, –NCH2CH3), 4.40 (1 H, t, H-4Ј, J4Ј,3Ј
=
5.2 Hz), 7.20–7.32 (5 H, m, aromatic); 13C-NMR (125 MHz,
CDCl3) δ 12.39 (–NCH2CH3), 12.61 (–NCH2CH3), 18.08 (C-3),
29.14 (C-3Ј), 30.20 (C-2Ј), 31.35 (C-2), 33.75 (C-1), 39.47
(–NCH2CH3), 42.01 (–NCH2CH3), 52.54 (–OCH3), 52.99
140.87 (C-1Љ), 169.36 (C᎐O); HR-MS (EI) 312.1945 (Mϩ,
᎐
requires m/z C18H24N4O 312.1950). Found: C, 69.03; H, 7.74;
N, 17.91. C18H24N4O requires C, 69.23; H, 7.69; N, 17.95%.
1206
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(–OCH3), 63.24 (C-1Ј), 104.17 (C-4Ј), 126.14 (C-2Љ and C-6Љ),
126.74 (C-4Љ), 128.78 (C-3Љ and C-5Љ), 140.48 (C-1Љ), 169.16
fied by column chromatography (silica gel, CHCl3–MeOH,
1 : 9) to give the free amine as an oil. After the free amine was
dissolved in MeOH, the resulting solution was put on a column
of Diaion WA-30 resin (ClϪ form), and the column was
developed with MeOH. The solvent was evaporated, and the
residue was treated with Et2O to give white crystals of 7 as a
hydrochloride salt (30 mg, 93%): mp (Et2O) 57–59 ЊC; [α]2D2
(C᎐O); HR-MS (EI) 374.2323 (Mϩ, C H N O requires m/z
᎐
20 30
4
3
374.2318). Found: C, 63.99; H, 7.98; N, 14.89. C20H30N4O3
requires C, 64.15; H, 8.07; N, 14.96%.
(1S,2R)-1-Phenyl-2-[(S)-1-azido-3-formylpropyl]-N,N-diethyl-
cyclopropanecarboxamide 14
1
ϩ46.0 (c 0.205, MeOH); H-NMR (500 MHz, CD3OD) δ 0.87
(3 H, t, –NCH2CH3, J = 7.1 Hz), 1.15 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.28–1.36 (3 H, m, H-3a and H-3b and H-2), 1.82 (1 H,
m, H-3Јa), 2.00 (1 H, m, H-3Јb), 2.08 (2 H, m, H-4Ј), 2.29 (1 H,
m, H-2Ј), 3.21 (1 H, m, –NCH2CH3), 3.27–3.50 (5 H, m, H-5Ј
and –NCH2CH3), 7.24–7.36 (5 H, m, aromatic); 13C-NMR
(125 MHz, CD3OD) δ 12.63 (–NCH2CH3), 13.23 (–NCH2-
CH3), 17.99 (C-3), 24.34 (C-3Ј), 30.96 (C-4Ј), 31.63 (C-2), 35.73
(C-1), 40.65 (–NCH2CH3), 43.22 (–NCH2CH3), 45.96 (C-5Ј),
65.02 (C-2Ј), 126.79 (C-2Љ and C-6Љ), 128.27 (C-4Љ), 130.01 (C-3Љ
A mixture of 12S (749 mg, 2.00 mmol) and TFA (80% aqueous
solution, 5 mL) in CH2Cl2 (10 mL) was stirred at room tem-
perature for 2 h and was then neutralized with NaHCO3. The
resulting mixture was evaporated, and the residue was purified
by column chromatography (silica gel, AcOEt–hexane, 1 : 4
then 1 : 2) to give 14 as an oil (375 mg, 57%): [α]2D1 Ϫ123.0
1
(c 0.675, CHCl3); H-NMR (500 MHz, CDCl3) δ 0.42 (3 H, t,
–NCH2CH3, J = 7.0 Hz), 1.12 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.15 (1 H, dd, H-3a, J3a,3b = 5.2, J3a,2 = 9.5 Hz), 1.56 (1 H, dd, H-
3b, J3b,3a = 5.2, J3b,2 = 6.6 Hz), 1.83 (1 H, ddd, H-2, J2,3b = 6.6,
J2,3a = 9.5, J2,1Ј = 9.5 Hz), 2.01 (1 H, m, H-2Јa), 2.09 (1 H, m,
H-2Јa), 2.58–2.74 (2 H, m, H-3Ј), 3.04–3.12 (2 H, m, H-1Ј and
–NCH2CH3), 3.22 (1 H, m, –NCH2CH3), 3.49 (1 H, m,
–NCH2CH3), 3.62 (1 H, m, –NCH2CH3), 7.21–7.40 (5 H, m,
aromatic), 9.82 (1 H, br s, H-4Ј); 13C-NMR (125 MHz, CDCl3)
δ 11.98 (–NCH2CH3), 12.31 (–NCH2CH3), 18.76 (C-3), 27.37
(C-2Ј), 28.58 (C-2), 35.91 (C-1), 39.92 (–NCH2CH3), 40.24
(C-3Ј), 41.97 (–NCH2CH3), 62.05 (C-1Ј), 126.71 (C-2Љ
and C-6Љ), 126.80 (C-4Љ), 128.79 (C-3Љ and C-5Љ), 140.33
and C-5Љ), 140.43 (C-1Љ), 171.77 (C᎐O); HR-MS (EI) 286.2054
᎐
(Mϩ, C18H27ClN4O3 requires m/z 286.2045). Found: C, 66.61;
H, 8.33; N, 8.29. C18H27ClN4O3 requires C, 66.96; H, 8.43;
N, 8.68%.
(1S,2R)-1-Phenyl-2-[(S)-1-azido-3-hydroxypropyl]-N,N-diethyl-
cyclopropanecarboxamide 17
A mixture of 16 (200 mg, 0.50 mmol) and NaOMe (28% in
MeOH, 0.50 mL) in MeOH (5.0 mL) was stirred at room
temperature for 1 h and then neutralized with AcOH. The
resulting mixture was evaporated, and the residue was par-
titioned between AcOEt and H2O. The organic layer was
washed with brine, dried (Na2SO4), evaporated, and purified by
column chromatography (silica gel; AcOEt–hexane, 1 : 1) to
give 17 as an oil (140 mg, 86%): mp (hexane–AcOEt) 77–79 ЊC;
(C-1Љ), 169.20 (C᎐O), 200.82 (C-4Ј); LR-MS (EI) m/z 328
᎐
(Mϩ); HR-MS (EI) 328.1917 (Mϩ, C18H24N4O2 requires m/z
328.1899). Found: C, 66.21; H, 7.49; N, 16.97. C18H24N4O2
requires C, 65.83; H, 7.37; N, 17.06%.
[α]2D3 Ϫ129.1 (c 0.700, CHCl3); H-NMR (500 MHz, CDCl3)
1
(1S,2R)-1-Phenyl-2-[(S)-(pyrrolin-5-yl)methyl]-N,N-diethyl-
δ 0.44 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.12 (1 H, dd, H-3a,
J3a,3b = 5.2, J3a,2 = 8.9 Hz), 1.13 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.58 (1 H, dd, H-3b, J3b,3a = 5.2, J3b,2 = 6.2 Hz), 1.70 (1 H, br s,
–OH), 1.89 (1 H, ddd, H-2, J2,3b = 6.2, J2,3a = 8.9, J2,1Ј = 8.9 Hz),
1.95–2.02 (2 H, m, H-2Ј), 3.08 (1 H, m, –NCH2CH3), 3.18–3.29
(2 H, m, H-1Ј and –NCH2CH3), 3.50 (1 H, m, –NCH2CH3),
3.65 (1 H, m, –NCH2CH3), 3.84 (2 H, t, H-3Ј, J3Ј,2Ј = 6.0 Hz),
7.21–7.33 (5 H, m, aromatic); 13C-NMR (100 MHz, CDCl3)
δ 11.94 (–NCH2CH3), 12.33 (–NCH2CH3), 19.06 (C-3), 28.60
(C-2), 36.05 (C-1), 37.71 (C-2Ј), 40.02 (–NCH2CH3), 42.06
(–NCH2CH3), 59.33 (C-3Ј), 60.24 (C-1Ј), 126.76 (C-2Љ and
C-6Љ), 126.81 (C-4Љ), 128.79 (C-3Љ and C-5Љ), 140.56 (C-1Љ),
cyclopropanecarboxamide 6
A mixture of 14 (65.7 mg, 0.20 mmol) and 10% Pd–charcoal
(20 mg) in MeOH (10 mL) was stirred under atmospheric pres-
sure of hydrogen at room temperature for 1 h, and then the
catalyst was filtered off. After the filtrate was evaporated, a mix-
ture of the residue and molecular sieves (5 Å in CH2Cl2, 3 mL)
was stirred at room temperature for 14 h, and then the mole-
cular sieves were filtered off. The filtrate was evaporated, and
the residue was purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 1 then 2 : 1) to give 6 as an oil (47 mg, 83%):
[α]2D2 Ϫ136.6 (c 0.135, CHCl3); H-NMR (500 MHz, CDCl3)
δ 0.40 (3 H, t, –NCH2CH3, J = 7.1 Hz), 0.83 (1 H, dd, H-3a,
J3a,3b = 4.8, J3a,2 = 9.3 Hz), 1.08 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.61 (1 H, m, H-4Јa), 1.70 (1 H, dd, H-3b, J3b,3a = 4.8, J3b,2
6.3 Hz), 1.97 (1 H, ddd, H-2, J2,3b = 6.3, J2,3a = 9.3, J2,1Ј
1
169.48 (C᎐O); HR-MS (EI) 316.1915 (Mϩ, C H N O requires
᎐
17 24
4
2
m/z 316.1899). Found: C, 64.73; H, 7.77; N, 17.47. C17H24N4O2
requires C, 64.53; H, 7.65; N, 17.71%.
=
=
9.3 Hz), 2.12 (1 H, m, H-4Јb), 2.44 (1 H, m, H-3Јa), 2.65 (1 H,
m, H-3Јb), 3.10 (1 H, m, –NCH2CH3), 3.18 (1 H, m,
–NCH2CH3), 3.48–3.57 (2 H, m, H-5Ј and –NCH2CH3), 3.90
(1 H, m, –NCH2CH3), 7.17–7.30 (5 H, m, aromatic), 7.64 (1 H,
t, H-2Ј, J2Ј,3Ј = 1.2 Hz); 13C-NMR (125 MHz, CDCl3) δ 12.04
(–NCH2CH3), 12.28 (–NCH2CH3), 19.62 (C-3), 27.69 (C-4Ј),
29.02 (C-2), 36.45 (C-3Ј), 37.02 (C-1), 39.75 (–NCH2CH3),
42.78 (–NCH2CH3), 73.01 (C-5Ј), 126.31 (C-4Љ), 126.99 (C-2Љ
and C-6Љ), 128.52 (C-3Љ and C-5Љ), 141.55 (C-1Љ), 166.67 (C-2Ј),
(1S,2R)-1-Phenyl-2-[(S)-1-amino-3-hydroxypropyl]-N,N-
diethylcyclopropanecarboxamide hydrochloride 2k
Compound 2k was prepared from 17 (200 mg, 0.60 mmol), as
described above for the synthesis of 15 from 11R. After appli-
cation of the resulting solution to a column of Diaion WA-30
resin (ClϪ form), white crystals of 2k (188 mg, 96%) were
obtained as a hydrochloride: mp (Et2O) 107–109 ЊC; [α]2D0 ϩ77.0
(c 1.200, MeOH); 1H-NMR (500 MHz, CD3OD) δ 0.91 (3 H, t,
–NCH2CH3, J = 7.1 Hz), 1.15 (3 H, t, –NCH2CH3, J = 7.1 Hz),
1.24 (1 H, ddd, H-2, J2,3a = 6.3, J2,3b = 9.0, J2,1Ј = 9.0 Hz), 1.41
(1 H, dd, H-3a, J3a,3b = 6.0, J3a,2 = 6.3 Hz), 1.91–2.05 (2 H, m,
H-2Ј), 2.14 (1 H, dd, H-3b, J3b,3a = 6.0, J3b,2 = 9.0 Hz), 3.02 (1 H,
m, H-1Ј), 3.38 (1 H, m, –NCH2CH3), 3.44–3.51 (3 H, m,
–NCH2CH3), 3.75–3.84 (2 H, m, H-3Ј), 7.26–7.37 (5 H, m, aro-
matic); 13C-NMR (125 MHz, CD3OD) δ 12.53 (–NCH2CH3),
13.20 (–NCH2CH3), 18.32 (C-3), 32.93 (C-2), 35.12 (C-1), 36.23
(C-2Ј), 40.92 (–NCH2CH3), 43.55 (–NCH2CH3), 54.91 (C-1Ј),
59.33 (C-3Ј), 126.83 (C-2Љ and C-6Љ), 128.41 (C-4Љ), 130.13 (C-3Љ
170.21 (C᎐O); HR-MS (EI) 284.1890 (Mϩ, C H N O requires
᎐
18 24
2
m/z 284.1889). Found: C, 75.66; H, 8.38; N, 9.79. C18H24N2O
requires C, 76.02; H, 8.51; N, 9.85%.
(1S,2R)-1-Phenyl-2-[(S)-(pyrrolidin-2-yl)methyl]-N,N-diethyl-
cyclopropanecarboxamide hydrochloride 7
A mixture of 6 (28 mg, 0.10 mmol) and NaBH3CN (13 mg,
0.20 mmol) in MeOH (2 mL) was stirred at room temperature
for 14 h. The resulting mixture was evaporated, and the residue
was partitioned between CHCl3 and H2O. The organic layer
was washed with brine, dried (Na2SO4), evaporated, and puri-
and C-5Љ), 140.28 (C-1Љ), 172.63 (C᎐O); HR-MS (EI) 290.2007
᎐
(Mϩ, C17H26N2O2 requires m/z 290.1994). Found: C, 62.47;
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
1207

View Article Online
H, 8.54; N, 8.28. C17H27ClN4O2 requires C, 62.47; H, 8.83;
N, 8.57%.
J2,3b = 6.2, J2,3a = 9.2, J2,1Ј = 9.2 Hz), 1.95 (1 H, m, H-2Јa), 2.07
(1 H, m, H-2Јb), 2.45 (3 H, s, CH3PhSO2–), 3.09 (1 H, m,
–NCH2CH3), 3.19–3.26 (2 H, m, H-1Ј and –NCH2CH3), 3.46
(1 H, m, –NCH2CH3), 3.55 (1 H, m, –NCH2CH3), 4.14 (1 H, t,
H-3Јa), 4.22 (1 H, t, H-3Јb), 7.22–7.36 (7 H, m, aromatic), 7.80
(2 H, d, aromatic, J = 8.2 Hz); 13C-NMR (100 MHz, CDCl3)
δ 12.14 (–NCH2CH3), 12.35 (–NCH2CH3), 18.07 (C-3), 29.52
(C-2), 34.38 (C-2Ј), 35.86 (C-1), 39.85 (–NCH2CH3), 41.84
(–NCH2CH3), 59.25 (C-1Ј), 66.75 (C-3Ј), 126.52, 126.85,
127.93, 128.82, 129.92, 132.77, 140.16, 144.93 (aromatic),
(1S,2R)-1-Phenyl-2-[(S)-1-azido-3-methoxypropyl]-N,N-diethyl-
cyclopropanecarboxamide 18
After a mixture of NaH (60% in paraffin liquid, 24 mg, 0.60
mmol) and 17 (158 mg, 0.50 mmol) in THF (5 mL) was stirred
at 0 ЊC for 40 min, MeI (93 µL, 1.5 mmol) was added to
the mixture, and the resulting mixture was stirred at the same
temperature for 30 min and at room temperature for a further
3 h. After quenching with MeOH, the mixture was partitioned
between AcOEt and H2O. The organic layer was washed with
brine, dried (Na2SO4), evaporated, and purified by column
chromatography (silica gel, AcOEt–hexane, 1 : 4) to give 18 as
169.02 (C᎐O); HR-MS (EI) 470.1965 (Mϩ, C H N O S
᎐
24 30
4
4
requires m/z 470.1988). Found: C, 61.21; H, 6.58; N, 12.21.
C24H30N4O4S requires C, 61.25; H, 6.43; N, 11.91%.
(1S,2R)-1-Phenyl-2-[(S)-(azetidin-2-yl)]-N,N-diethylcyclo-
propanecarboxamide hydrochloride 5
an oil (149 mg, 90%): [α]2D2 Ϫ169.7 (c 0.455, CHCl3); H-NMR
1
(500 MHz, CDCl3) δ 0.40 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.02
A mixture of 19 (188 mg, 0.40 mmol) and 10% Pd–charcoal
(50 mg) in THF (30 mL) and MeOH (2 mL) was stirred under
atmospheric pressure of hydrogen at room temperature for
12 h, and then the catalyst was filtered off. The filtrate was
evaporated, and the residue was purified by column chrom-
atography (silica gel, AcOEt–hexane, 1 : 1, then CHCl3–MeOH,
9 : 1) to give the free amine as an oil. After the free amine was
dissolved in MeOH, the resulting solution was put on a column
of Diaion WA-30 resin (ClϪ form), and the column was
developed with MeOH. The solvent was evaporated, and the
residue was treated with Et2O to give white crystals of 5 as a
hydrochloride salt (93 mg, 75%): mp (Et2O) 83–85 ЊC; [α]2D4
(1 H, dd, H-3a, J3a,3b = 4.8, J3a,2 = 9.2 Hz), 1.13 (3 H, t,
–NCH2CH3, J = 7.0 Hz), 1.62 (1 H, dd, H-3b, J3b,3a = 4.8, J3b,2
=
6.0 Hz), 1.87–1.98 (2 H, m, H-2 and H-2Јa), 2.05 (1 H, m,
H-2Јb), 3.06 (1 H, m, –NCH2CH3), 3.13–3.23 (2 H, m, H-1Ј and
–NCH2CH3), 3.34 (1 H, m, –NCH2CH3), 3.48–3.57 (3 H, m,
H-3Ј and –NCH2CH3), 3.71 (1 H, m, –NCH2CH3), 7.21–7.33
(5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3) δ 11.92
(–NCH2CH3), 12.34 (–NCH2CH3), 19.25 (C-3), 28.26
(C-2), 35.29 (C-2Ј), 36.10 (C-1), 39.97 (–NCH2CH3), 41.98
(–NCH2CH3), 58.62 (–OMe), 60.37 (C-1Ј), 68.89 (C-3Ј), 126.67
(C-4Љ), 126.89 (C-2Љ and C-6Љ), 128.72 (C-3Љ and C-5Љ), 140.73
(C-1Љ), 169.27 (C᎐O); HR-MS (EI) 330.2035 (Mϩ, C H N O
᎐
18 26
4
2
1
ϩ62.7 (c 1.105, MeOH); H-NMR (500 MHz, CD3OD) δ 0.91
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.14 (3 H, t, –NCH2CH3, J =
requires m/z 330.2056). Found: C, 65.33; H, 7.92; N, 16.63.
C18H26N4O2 requires C, 65.43; H, 7.93; N, 16.96%.
7.0 Hz), 1.23 (1 H, ddd, H-2, J2,3a = 6.5, J2,3b = 9.0, J2,1Ј
=
9.5 Hz), 1.35 (1 H, dd, H-3a, J3a,3b = 6.0, J3a,2 = 6.5 Hz), 1.98
(1 H, m, H-3Јa), 2.06 (1 H, m, H-3Јb), 2.14 (1 H, dd, H-3b,
J3b,3a = 6.0, J3b,2 = 9.0 Hz), 2.97 (1 H, m, H-1Ј), 3.36 (1 H, m,
–NCH2CH3), 3.44–3.62 (3 H, m, –NCH2CH3), 3.59–3.62 (2 H,
m, H-4Ј), 7.25–7.37 (5 H, m, aromatic); 13C-NMR (125 MHz,
CD3OD) δ 12.53 (–NCH2CH3), 13.21 (–NCH2CH3), 18.26
(C-3), 32.80 (C-2), 33.80 (C-3Ј), 35.30 (C-1), 40.93 (–NCH2-
CH3), 43.56 (–NCH2CH3), 55.20 (C-2Ј), 59.04 (C-4Ј), 126.84
(C-2Љ and C-6Љ), 128.44 (C-4Љ), 130.13 (C-3Љ and C-5Љ), 140.24
(1S,2R)-1-Phenyl-2-[(S)-1-amino-3-methoxypropyl]-N,N-
diethylcyclopropanecarboxamide hydrochloride 2l
Compound 2l was prepared from 18 (83 mg, 0.25 mmol), as
described above for the synthesis of 15 from 11R. After appli-
cation of the resulting solution to a column of Diaion WA-30
resin (ClϪ form), white crystals of 2l (79 mg, 93%) were
obtained as a hydrochloride salt: mp (Et2O) 151–152 ЊC; [α]2D1
1
ϩ88.3 (c 0.430, MeOH); H-NMR (500 MHz, CD3OD) δ 0.90
(C-1Љ), 172.62 (C᎐O); HR-MS (EI) 272.1902 (Mϩ, C H N O
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.14 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.24 (1 H, ddd, H-2, J2,3a = 6.7, J2,3b = 9.0, J2,1Ј
᎐
17 24
2
=
requires 272.1889). Found: C, 66.01; H, 8.24; N, 9.00.
C17H25ClN2O requires C, 66.11; H, 8.16; N, 9.07%.
10.4 Hz), 1.36 (1 H, dd, H-3a, J3a,3b = 6.0, J3a,2 = 6.7 Hz), 1.99
(2 H, m, H-2Јa), 2.08 (2 H, m, H-2Јb), 2.15 (1 H, dd, H-3b,
J3b,3a = 6.0, J3b,2 = 9.0 Hz), 2.98 (1 H, m, H-1Ј), 3.36 (3 H, s,
–OMe), 3.38 (1 H, m, –NCH2CH3), 3.44–3.50 (3 H, m, –NCH2-
CH3), 3.59–3.64 (2 H, m, H-3Ј), 7.26–7.34 (5 H, m, aromatic);
13C-NMR (125 MHz, CD3OD) δ 12.54 (–NCH2CH3), 13.22
(–NCH2CH3), 18.29 (C-3), 32.76 (C-2), 33.78 (C-2Ј, 35.29 (C-1),
40.92 (–NCH2CH3), 43.56 (–NCH2CH3), 55.19 (C-1Ј), 59.09
(–OMe), 70.13 (C-3Ј), 126.86 (C-2Љ and C-6Љ), 128.42 (C-4Љ),
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylamino-3-
(pivaloyloxy)propyl]-N,N-diethylcyclopropanecarboxamide 20
A mixture of 16 (801 mg, 2.00 mmol), 10% Pd–charcoal
(100 mg) and (Boc)2O (0.51 mL, 2.2 mmol) in MeOH (5 mL)
was stirred under atmospheric pressure of hydrogen at room
temperature for 12 h, and then the catalyst was filtered off. The
filtrate was evaporated, and the residue was purified by column
chromatography (silica gel, AcOEt–hexane, 1 : 2) to give 20 as
white crystals (812 mg, 86%): mp (hexane–AcOEt) 139–141 ЊC;
[α]2D1 Ϫ70.3 (c 1.015, CHCl3); 1H-NMR (500 MHz, CDCl3)
δ 0.60 (3 H, br s, –NCH2CH3), 1.13 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.19 (9 H, s, –COC(CH3)3), 1.20 (1 H, br s, H-3a), 1.32
(1 H, br s, H-3b), 1.41 (9 H, s, –OCOC(CH3)3), 1.78 (1 H, br s,
H-2), 2.09 (1 H, m, H-2Јa), 2.34 (1 H, m, H-2Јb), 3.14 (1 H, m,
H-1Ј), 3.27 (1 H, m, –NCH2CH3), 3.35 (1 H, m, –NCH2CH3),
3.47 (1 H, m, –NCH2CH3), 3.56 (1 H, m, –NCH2CH3), 4.11–
4.21 (2 H, m, H-3Ј), 5.00 (1 h, br s, –NH–), 7.18–7.36 (5 H, m,
aromatic); 13C-NMR (125 MHz, CDCl3) δ 12.27 (–NCH2CH3),
12.52 (–NCH2CH3), 17.23 (C-3), 27.17 (–COC(CH3)3), 28.37
(–OCOC(CH3)3), 30.83 (C-2), 33.70 (C-2Ј), 34.03 (C-1), 38.68
(–COC(CH3)3), 39.94 (–NCH2CH3), 42.34 (–NCH2CH3), 48.25
(C-1Ј), 61.55 (C-3Ј), 78.90 (–OCOC(CH3)3), 126.38 (C-2Љ and
C-6Љ), 126.48 (C-4Љ), 128.66 (C-3Љ and C-5Љ), 140.99 (C-1Љ),
130.12 (C-3Љ and C-5Љ), 140.24 (C-1Љ), 172.61 (C᎐O); HR-MS
᎐
(EI) 304.2154 (Mϩ, C18H28N2O2 requires 304.2151). Found:
C, 63.69; H, 8.47; N, 8.12. C18H29ClN2O2 requires C, 63.42;
H, 8.57; N, 8.22%.
(1S,2R)-1-Phenyl-2-[(S)-1-azido-3-tosyloxypropyl]-N,N-diethyl-
cyclopropanecarboxamide 19
A mixture of 17 (127 mg, 0.40 mmol), TsCl (229 mg, 1.20
mmol), Et3N (0.34 mL, 2.40 mmol) and DMAP (14.7 mg,
0.12 mmol) in CH2Cl2 (5.00 mL) was stirred at room temper-
ature for 9 h, and the resulting solution was partitioned with
H2O. The organic layer was washed with brine, dried (Na2SO4),
evaporated, and purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 3) to give 19 as an oil (186 mg, 99%): [α]2D2
1
Ϫ66.1 (c 0.140, CHCl3); H-NMR (500 MHz, CDCl3) δ 0.49
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.10 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.10 (1 H, dd, H-3a, J3a,3b = 5.2, J3a,2 = 9.2 Hz), 1.41
(1 H, dd, H-3b, J3b,3a = 5.1, J3b,2 = 6.5 Hz), 1.68 (1 H, ddd, H-2,
155.38 (C᎐O), 170.72 (C᎐O), 178.58 (C᎐O); HR-MS (EI)
᎐
᎐
᎐
474.3091 (Mϩ, C27H42N2O5 requires m/z 474.3093). Found: C,
1208
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212

View Article Online
68.12; H, 8.91; N, 5.79. C27H42N2O5 requires C, 68.32; H, 8.92;
N, 5.90%.
ated aqueous NH4Cl and AcOEt were added to the reaction
mixture, and the resulting mixture was partitioned. The organic
layer was washed with brine, dried (Na2SO4), evaporated, and
purified by column chromatography (silica gel, AcOEt–hexane,
1 : 4) to give 23 as a white powder (26 mg, 34%). A solution of
23 (26 mg, 0.068 mmol) in 1.0 M HCl–MeOH (2 mL) was
heated under reflux for 1 h. The solvent was evaporated, and the
residue was treated with Et2O to give white crystals of 2i as a
hydrochloride salt (19 mg, 88%): mp (Et2O) 178–180 ЊC; [α]2D1
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylamino-3-
hydroxypropyl]-N,N-diethylcyclopropanecarboxamide 21
Compound 21 was prepared from 20 (712 mg, 1.50 mmol), as
described above for the synthesis of 17 from 16. After purifi-
cation by column chromatography (silica gel, AcOEt–hexane,
1 : 1), 21 was obtained as white crystals (413 mg, 71%): mp
(hexane–AcOEt) 126–128 ЊC; [α]2D3 Ϫ106.1 (c 0.810, CHCl3);
1H-NMR (500 MHz, CDCl3) δ 0.54 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.13 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.21 (1 H, dd,
H-3a, J3a,3b = 5.0, J3a,2 = 9.0 Hz), 1.43 (9 H, s, –OCOC(CH3)3),
1.48 (1 H, dd, H-3b, J3b,3a = 5.0, J3b,2 = 6.2 Hz), 1.74 (1 H, ddd,
H-2, J2,3b = 6.2, J2,3a = 9.0, J2,1Ј = 9.0 Hz), 1.86 (1 H, m, H-2Јa),
2.01 (1 H, m, H-2Јb), 3.09 (1 H, m, –NCH2CH3), 3.22–3.42 (3
H, m, H-1Ј and –NCH2CH3), 3.58–3.68 (4 H, m, H-3Ј and –OH
and –NCH2CH3), 5.10 (1 H, d, –NH–, JNH,1Ј = 8.2 Hz), 7.19–
7.32 (5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3) δ 12.41
(–NCH2CH3), 12.52 (–NCH2CH3), 17.91 (C-3), 28.34 (–OC-
OC(CH3)3), 30.79 (C-2), 34.87 (C-1), 40.13 (–NCH2CH3),
42.37 (–NCH2CH3), 47.45 (C-1Ј), 58.90 (C-3Ј), 79.47 (–OC-
OC(CH3)3), 126.39 (C-2Љ and C-6Љ), 126.51 (C-4Љ), 128.67 (C-3Љ
1
ϩ82.1 (c 0.200, MeOH); H-NMR (500 MHz, CDCl3) δ 0.89
(3 H, t, –NCH2CH3, J = 7.0 Hz), 1.14 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.20 (1 H, ddd, H-2, J2,3a = 6.5, J2,3b = 9.0, J2,1Ј
=
10.4 Hz), 1.36 (1 H, dd, H-3a, J3a,3b = 6.0, J3a,2 = 6.5 Hz), 2.13
(1 H, dd, H-3b, J3b,3a = 6.0, J3b,2 = 9.0 Hz), 2.51–2.59 (2 H, m,
H-2Ј), 2.92 (1 H, m, H-1Ј), 3.39 (1 H, m, –NCH2CH3), 3.42–
3.49 (3 H, m, –NCH2CH3), 5.22–5.28 (2 H, m, H-4Ј), 5.88 (1 H,
m, H-3Ј), 7.26–7.37 (5 H, m, aromatic); 13C-NMR (125 MHz,
CDCl3) δ 12.52 (–NCH2CH3), 13.17 (–NCH2CH3), 18.55 (C-3),
32.85 (C-2), 35.18 (C-1), 38.68 (C-2Ј), 40.93 (–NCH2CH3),
43.56 (–NCH2CH3), 56.00 (C-1Ј), 120.41 (C-4Ј), 126.84 (C-2Љ
and C-6Љ), 128.45 (C-4Љ), 130.14 (C-3Љ and C-5Љ), 140.25 (C-1Љ),
172.61 (C᎐O); HR-MS (EI) 284.2022 ((M Ϫ HCl)ϩ, C H N O
᎐
18 26
2
requires m/z 286.2045). Found: C, 66.65; H, 8.16; N, 8.50.
C18H27ClN2O requires C, 66.96; H, 8.43; N, 8.68%.
and C-5Љ), 141.02 (C-1Љ), 156.52 (C᎐O), 170.46 (C᎐O); HR-MS
᎐
᎐
(EI) 390.2498 (Mϩ, C22H34N2O4 requires m/z 390.2518). Found:
C, 67.79; H, 8.86; N, 7.03. C22H34N2O4 requires C, 67.66; H,
8.78; N, 7.17%.
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylamino-4,4-
dibromobut-3-enyl]-N,N-diethylcyclopropanecarboxamide 24
To a solution of 22 (117 mg, 0.30 mmol) in CH2Cl2 (3 mL) were
added PPh3 (315 mg, 1.20 mmol) and CBr4 (199 mg, 0.60 mmol)
at 0 ЊC, and the mixture was stirred at the same temperature for
5 min and then quenched with saturated aqueous NaHCO3.
The resulting mixture was evaporated, and the residue was par-
titioned between AcOEt and H2O. The organic layer was
washed with brine, dried (Na2SO4), evaporated, and purified by
column chromatography (silica gel, AcOEt–hexane, 1 : 4) to
give 24 as white crystals (103 mg, 61%): mp (hexane–AcOEt)
195–196 ЊC; [α]2D1 Ϫ64.5 (c 0.450, CHCl3); 1H-NMR (500 MHz,
CDCl3) δ 0.55 (3 H, br s, –NCH2CH3), 1.12 (3 H, t, –NCH2CH3,
J = 7.0 Hz), 1.25 (1 H, br s, H-3a), 1.43 (9 H, s, –OCOC(CH3)3),
1.44 (1 H, br s, H-2), 1.78 (1 H, br s, H-3b), 2.58 (1 H, m,
H-2Јa), 2.71 (1 H, m, H-2Јb), 3.08 (1 H, m, H-1Ј), 3.24–3.40
(2 H, m, –NCH2CH3), 3.47 (1 H, m, –NCH2CH3), 3.58 (1 H, m,
–NCH2CH3), 4.99 (1 H, d, –NH–, JNH,1Ј = 8.5 Hz), 6.49 (1 H, t,
H-3Ј, J3Ј,2Ј = 7.3 Hz), 7.19–7.31 (5 H, m, aromatic); 13C-NMR
(125 MHz, CDCl3) δ 12.44 (–NCH2CH3), 12.57 (–NCH2CH3),
17.87 (C-3), 28.39 (–OCOC(CH3)3), 30.10 (C-2), 34.78 (C-1),
38.82 (C-2Ј), 40.05 (–NCH2CH3), 42.34 (–NCH2CH3), 50.09
(C-1Ј), 79.26 (–OCOC(CH3)3), 90.40 (C-4Ј), 126.49 (C-2Љ and
C-6Љ), 126.61 (C-4Љ), 128.69 (C-3Љ and C-5Љ), 135.40 (C-1Ј),
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylamino-2-
formylethyl]-N,N-diethylcyclopropanecarboxamide 22
To a solution of oxalyl chloride (0.17 mL, 2.0 mmol) in CH2Cl2
(5 mL) was slowly added a solution of DMSO (0.28 mL,
4.0 mmol) in CH2Cl2 (3 mL) at Ϫ78 ЊC over 30 min. After slow
addition of a solution of 21 (391 mg, 1.00 mmol) in CH2Cl2
(5 mL), the resulting mixture was stirred at the same temper-
ature for 1 h, and then Et3N (1.12 mL, 8.00 mmol) was added.
After stirring the mixture at Ϫ78 ЊC for a further 10 min, satur-
ated aqueous NH4Cl, and then CH2Cl2 were added and par-
titioned. The organic layer was washed with brine, dried
(Na2SO4), evaporated, and purified by column chromatography
(silica gel, AcOEt–hexane, 1 : 3) to give 22 as white crystals
(275 mg, 71%): mp (hexane–AcOEt) 158–160 ЊC; [α]2D1 Ϫ76.0
1
(c 0.545, CHCl3); H-NMR (500 MHz, CDCl3) δ 0.59 (3 H, t,
–NCH2CH3, J = 7.0 Hz), 1.14 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.27 (1 H, br s, H-3a), 1.37 (1 H, br s, H-3b), 1.41 (9 H, s,
–OCOC(CH3)3), 1.92 (1 H, m, H-2), 2.93 (1 H, dd, H-1Ј, J1Ј,2Јa
=
5.2, J1Ј,2 = 7.2 Hz), 3.08–3.15 (2 H, m, H-2Јa and –NCH2CH3),
3.28–3.40 (2 H, m, –NCH2CH3), 3.57 (1 H, m, –NCH2CH3),
3.82 (1 H, br s, H-2Јb), 5.26 (1 H, br s, –NH–), 7.19–7.31 (5 H,
m, aromatic), 9.79 (1 H, br s, H-3Ј); 13C-NMR (125 MHz,
CDCl3) δ 12.50 (–NCH2CH3), 12.52 (–NCH2CH3), 17.47 (C-3),
28.34 (–OCOC(CH3)3), 30.29 (C-2), 34.83 (C-1), 39.97
(–NCH2CH3), 42.33 (–NCH2CH3), 46.65 (C-1Ј), 48.87 (C-2Ј),
79.25 (–OCOC(CH3)3), 126.35 (C-2Љ and C-6Љ), 126.63 (C-4Љ),
140.74 (C-1Љ), 155.25 (C᎐O), 170.29 (C᎐O); HR-MS (EI)
᎐
᎐
388.2380 (Mϩ, C24H36N2O4 requires m/z 388.2362). Found: C,
51.18; H, 6.37; N, 5.13. C22H32N2O4 requires C, 51.44; H, 6.48;
N, 5.00%.
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylaminobut-3-
ynyl]-N,N-diethylcyclopropanecarboxamide 25
128.72 (C-3Љ and C-5Љ), 140.61 (C-1Љ), 155.23 (C᎐O), 170.37
᎐
(C᎐O), 200.93 (C-3Ј); HR-MS (EI) 388.2380 (Mϩ, C H N O
᎐
22 32
2
4
To a solution of 24 (56 mg, 0.10 mmol) in THF (5 mL) was
slowly added a BuLi solution (1.5 M in hexane, 0.20 mL,
0.30 mmol) at Ϫ78 ЊC, and the mixture was warmed slowly to
Ϫ50 ЊC over 2 h. To the resulting mixture, saturated aqueous
NH4Cl and AcOEt were added and partitioned. The separated
organic layer was washed with brine, dried (Na2SO4), evapor-
ated, and purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 4) to give 25 as white crystals (23 mg, 60%):
mp (hexane–AcOEt) 177–178 ЊC; [α]2D1 Ϫ98.0 (c 0.125, CHCl3);
1H-NMR (500 MHz, CDCl3) δ 0.50 (3 H, br s, –NCH2CH3),
1.12 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.14 (1 H, br s, H-3a),
1.43 (9 H, s, –OCOC(CH3)3), 1.45–1.55 (2 H, m, H-2 and H-3b),
2.03 (2 H, d, H-2Ј, J2Ј,1Ј = 10.2 Hz), 2.73 (1 H, br s, H-4Ј), 3.04
requires m/z 388.2362). Found: C, 67.78; H, 8.38; N, 7.14.
C22H32N2O4 requires C, 68.01; H, 8.30; N, 7.21%.
(1S,2R)-1-Phenyl-2-[(S)-1-aminobut-3-enyl]-N,N-diethylcyclo-
propanecarboxamide hydrochloride 2i
To a suspension of methyltriphenylphosphonium bromide
(286 mg, 0.80 mmol) in THF (5 mL) was added a BuLi solution
(1.50 M in hexane, 0.53 mL, 0.80 mmol) at Ϫ78 ЊC, and the
resulting mixture was warmed slowly to 0 ЊC and then stirred
for 30 min. After the mixture was cooled to Ϫ40 ЊC, a solution
of 22 (68 mg, 0.20 mmol) was added, and the resulting mixture
was stirred at the same temperature for a further 10 min. Satur-
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
1209

View Article Online
(1 H, m, H-1Ј), 3.28–3.37 (2 H, m, –NCH2CH3), 3.52 (1 H,
m, –NCH2CH3), 3.62 (1 H, m, –NCH2CH3), 5.06 (1 H, br s,
–NH–), 7.19–7.31 (5 H, m, aromatic); 13C-NMR (125 MHz,
CDCl3) δ 12.33 (–NCH2CH3), 12.52 (–NCH2CH3), 18.41 (C-3),
24.99 (C-2Ј), 28.37 (–OCOC(CH3)3), 28.39 (C-2), 35.16 (C-1),
40.07 (–NCH2CH3), 42.36 (–NCH2CH3), 49.62 (C-1Ј), 70.35
(C-4Ј), 79.24 (–OCOC(CH3)3), 81.15 (C-3Ј), 126.56 (C-2Љ and
C-6Љ), 126.65 (C-4Љ), 128.65 (C-3Љ and C-5Љ), 140.90 (C-1Љ),
155.02 (C᎐O), 170.13 (C᎐O); HR-MS (EI) 384.2393 (Mϩ,
HR-MS (EI) 341.1935 (Mϩ, C17H23N7O requires m/z 341.1964).
Found: C, 59.98; H, 7.02; N, 28.58. C17H23N7O requires C,
59.81; H, 6.79; N, 28.72%.
(1S,2R)-1-Phenyl-2-[(S)-1,3-diaminopropyl]-N,N-diethylcyclo-
propanecarboxamide dihydrochloride 2m
Compound 2m was prepared from 27S (171 mg, 0.50 mmol), as
described above for the synthesis of 2i from 23. After treatment
with Et2O, white crystals of 2m were obtained as a hydro-
chloride salt (175 mg, 97%): mp (Et2O) 199–200 ЊC; [α]2D4 ϩ62.7
(c 1.105, MeOH); 1H-NMR (500 MHz, CD3OD) δ 0.90 (3 H, t,
–NCH2CH3, J = 7.0 Hz), 1.15 (3 H, t, –NCH2CH3, J = 7.0 Hz),
1.26 (1 H, ddd, H-2, J2,3a = 6.5, J2,3b = 9.0, J2,1Ј = 10.3 Hz), 1.50
(1 H, dd, H-3a, J3a,3b = 6.0, J3a,2 = 6.5 Hz), 2.19 (1 H, m, H-2Јa),
2.20 (1 H, dd, H-3b, J3b,3a = 6.0, J3b,2 = 9.0 Hz), 2.25 (1 H, m,
H-2Јb), 3.09 (1 H, m, H-1Ј), 3.19 (2 H, m, H-3Ј), 3.36 (1 H, m,
–NCH2CH3), 3.44–3.51 (3 H, m, –NCH2CH3), 7.26–7.38 (5 H,
m, aromatic); 13C-NMR (125 MHz, CD3OD) δ 12.53 (–NCH2-
CH3), 13.14 (–NCH2CH3), 18.30 (C-3), 32.48 (C-2Ј), 32.55
(C-2), 34.90 (C-1), 37.31 (C-3Ј), 40.96 (–NCH2CH3), 43.57
(–NCH2CH3), 53.69 (C-1Ј), 126.89 (C-2Љ and C-6Љ), 128.51
᎐
᎐
C24H36N2O4 requires m/z 384.2413). Found: C, 71.50; H, 8.50;
N, 7.18. C22H32N2O4 requires C, 71.84; H, 8.39; N, 7.29%.
(1S,2R)-1-Phenyl-2-[(S)-1-aminobut-3-ynyl]-N,N-diethylcyclo-
propanecarboxamide hydrochloride 2j
Compound 2j was prepared from 25 (19 mg, 0.050 mmol), as
described above for the synthesis of 2i from 23. After treatment
with Et2O, white crystals of 2j were obtained as a hydrochloride
salt (16 mg, 94%): mp (Et2O) 160–162 ЊC; [α]2D3 ϩ78.4 (c 0.170,
CHCl3); 1H-NMR (500 MHz, CDCl3) δ 0.89 (3 H, t,
–NCH2CH3, J = 7.1 Hz), 1.15 (3 H, t, –NCH2CH3, J = 7.1 Hz),
1.37 (1 H, ddd, H-2, J2,3a = 6.5, J2,3b = 8.9, J2,1Ј = 10.2 Hz), 1.44
(1 H, dd, H-3a, J3a,3b = 6.1, J3a,2 = 6.5 Hz), 2.15 (1 H, dd, H-3b,
J3b,3a = 6.1, J3b,2 = 8.9 Hz), 2.60 (1 H, t, H-4Ј, J4Ј,2Ј = 2.6 Hz), 2.74
(2 H, m, H-2Ј), 3.05 (1 H, m, H-1Ј), 3.38 (1 H, m, –NCH2CH3),
3.42–3.49 (3 H, m, –NCH2CH3), 7.27–7.38 (5 H, m, aromatic);
13C-NMR (125 MHz, CDCl3) δ 12.52 (–NCH2CH3), 13.15
(–NCH2CH3), 18.18 (C-3), 23.30 (C-2Ј), 32.21 (C-2), 35.45
(C-1), 40.95 (–NCH2CH3), 43.57 (–NCH2CH3), 54.76 (C-1Ј),
74.48 (C-4Ј), 78.19 (C-3Ј), 126.84 (C-2Љ and C-6Љ), 128.54
(C-4Љ), 130.16 (C-3Љ and C-5Љ), 139.98 (C-1Љ), 172.41 (C᎐O);
᎐
HR-MS (EI) 289.2126 (Mϩ, C17H27N3O requires m/z 289.2154).
Found: C, 56.04; H, 8.23; N, 11.39. C17H29Cl2N3O requires C,
56.35; H, 8.07; N, 11.60%.
(1S,2R)-1-Phenyl-2-[(S)-1-tert-butoxycarbonylaminopropyl]-
N,N-diethylcyclopropanecarboxamide 28
A mixture of 2b (310 mg, 1.00 mmol), (Boc)2O (0.25 mL, 1.10
mmol) and Et3N (0.21 mL, 1.5 mmol) in CH2Cl2 (5 mL) was
stirred at room temperature for 14 h. The mixture was evapor-
ated, and the residue was partitioned between AcOEt and H2O.
The organic layer was washed with brine, dried (Na2SO4), evap-
orated, and purified by column chromatography (silica gel,
AcOEt–hexane, 1 : 1) to give 28 as white crystals (160 mg, 43%):
mp (hexane–AcOEt) 193–194 ЊC; [α]2D2 Ϫ130.8 (c 0.530, CHCl3);
1H-NMR (500 MHz, CDCl3) δ 0.54 (3 H, br s, –NCH2CH3),
0.95 (3 H, t, H-3Ј, J3Ј,2Ј = 7.4 Hz), 1.14 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.18 (1 H, br s, H-3a), 1.42 (9 H, s, –C(CH3)3), 1.44
(1 H, br s, H-2), 1.73–1.87 (3 H, m, H-3b and H-2Ј), 3.08
(1 H, m, H-1Ј), 3.25–3.41 (3 H, m, –NCH2CH3), 3.62 (1 H, m,
–NCH2CH3), 3.62 (1 H, m, –NCH2CH3), 4.81 (1 H, br s, –NH–),
7.18–7.30 (5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3)
δ 10.58 (C-3Ј), 12.42 (–NCH2CH3), 12.58 (–NCH2CH3), 17.90
(C-3), 28.26 (C-2Ј), 28.40 (–C(CH3)3), 30.42 (C-2), 34.24 (C-1),
40.07 (–NCH2CH3), 42.39 (–NCH2CH3), 52.31 (C-1Ј), 78.69
(–C(CH3)3), 126.36 (C-2Љ and C-6Љ), 126.57 (C-4Љ), 128.58 (C-3Љ
(C-4Љ), 130.17 (C-3Љ and C-5Љ), 140.07 (C-1Љ), 172.52 (C᎐O);
᎐
HR-MS (EI) 284.1875 (Mϩ, C18H24N2O requires m/z 284.1889).
Found: C, 67.19; H, 7.64; N, 8.47. C18H25ClN2O requires C,
67.38; H, 7.85; N, 8.73%.
(1S,2R)-1-Phenyl-2-[(S)-1,3-diazidopropyl]-N,N-diethylcyclo-
propanecarboxamide 27S and (1S,2R)-1-phenyl-2-[(R)-1,3-
diazidopropyl]-N,N-diethylcyclopropanecarboxamide 27R
Compound 26 (583 mg, 2.00 mmol) was treated as described
above for the synthesis of 11R from 9. After purification by
column chromatography (silica gel, AcOEt–hexane, 1 : 9), 27S
as an oil (337 mg, 49%) and 27R as an oil (150 mg, 22%) were
obtained, respectively. 27S: [α]2D3 Ϫ127.9 (c 1.390, CHCl3); H-
1
NMR (500 MHz, CDCl3) δ 0.45 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.13 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.15 (1 H, dd,
H-3a, J3a,3b = 5.0, J3a,2 = 9.2 Hz), 1.56 (1 H, dd, H-3b, J3b,3a = 5.0,
J3b,2 = 6.2 Hz), 1.85 (1 H, ddd, H-2, J2,3b = 6.2, J2,3a = 9.2, J2,1Ј
=
9.6 Hz), 1.90–2.02 (2 H, m, H-2Ј), 3.10 (1 H, m, –NCH2CH3),
3.17 (1 H, m, H-1Ј), 3.23 (1 H, m, –NCH2CH3), 3.45–3.55 (3 H,
m, H-3Ј and –NCH2CH3), 3.63 (1 H, m, –NCH2CH3), 7.22–7.35
(5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3) δ 12.03
(–NCH2CH3), 12.35 (–NCH2CH3), 18.71 (C-3), 28.68 (C-2),
34.27 (C-2Ј), 35.99 (C-1), 39.99 (–NCH2CH3), 41.97 (–NCH2-
CH3), 47.99 (C-3Ј), 60.24 (C-1Ј), 126.75 (C-2Љ and C-6Љ), 126.85
and C-5Љ), 141.39 (C-1Љ), 155.51 (C᎐O), 170.65 (C᎐O); MS (EI)
᎐
᎐
m/z 374 (Mϩ). Found: C, 70.53; H, 9.11; N, 7.41. C22H34N2O3
requires C, 70.55; H, 9.15; N, 7.48%.
(1S,2R)-1-Phenyl-2-[(S)-1-(N-methylamino)propyl]-N,N-diethyl-
cyclopropanecarboxamide hydrochloride 4
(C-4Љ), 128.83 (C-3Љ and C-5Љ), 140.34 (C-1Љ), 169.11 (C᎐O);
᎐
HR-MS (EI) 341.1976 (Mϩ, C17H23N7O requires m/z 341.1964).
Found: C, 60.00; H, 6.99; N, 28.48. C17H23N7O requires C,
59.81; H, 6.79; N, 28.72%. 27R: [α]2D3 ϩ12.8 (c 1.310, CHCl3);
1H-NMR (500 MHz, CDCl3) δ 0.74 (3 H, t, –NCH2CH3, J =
7.0 Hz), 1.12 (3 H, t, –NCH2CH3, J = 7.0 Hz), 1.48 (1 H, ddd,
H-2, J2,3a = 6.8, J2,3b = 8.7, J2,1Ј = 9.0 Hz), 1.53 (1 H, dd, H-3a,
To a solution of 28 (112 mg, 0.30 mmol) in THF (3 mL) was
slowly added a BuLi solution (1.50 M in hexane, 0.24 mL,
0.36 mmol) at Ϫ78 ЊC, and the mixture was slowly warmed to
Ϫ15 ЊC. To the mixture was added MeI (56 µL, 0.90 mmol), and
the resulting mixture was stirred at the same temperature for
1 h. After addition of saturated aqueous NH4Cl, the mixture
was concentrated (for removal of THF), and the residue was
partitioned between AcOEt and H2O. The organic layer was
washed with brine, dried (Na2SO4), evaporated, and purified by
column chromatography (silica gel, AcOEt–hexane, 1 : 4) to
give 29 as a white powder (107 mg, 92%), which was treated as
described for the synthesis of 2i from 23. After treatment with
Et2O, white crystals of 4 were obtained as a hydrochloride salt
(85 mg, 95%): mp (Et2O) 126–127 ЊC; [α]2D2 Ϫ106.0 (c 0.415,
J3a,3b = 5.2, J3a,2 = 6.8 Hz), 1.67 (1 H, dd, H-3b, J3b,3a = 5.2, J3b,2
=
8.7 Hz), 1.83 (1 H, m, H-2Јa), 2.37 (1 H, m, H-2Јb), 3.21 (1 H,
m, –NCH2CH3), 3.26 (1 H, m, –NCH2CH3), 3.38–3.52 (4 H, m,
H-3Ј and –NCH2CH3 × 2), 7.22–7.27 (3 H, m, aromatic), 7.30–
7.33 (3 H, m, aromatic); 13C-NMR (125 MHz, CDCl3) δ 12.38
(–NCH2CH3), 12.76 (–NCH2CH3), 17.59 (C-3), 32.18 (C-2),
33.48 (C-1), 34.33 (C-2Ј), 39.45 (–NCH2CH3), 41.91 (–NCH2-
CH3), 48.41 (C-3Ј), 61.19 (C-1Ј), 125.87 (C-2Љ and C-6Љ), 126.86
1
(C-4Љ), 128.85 (C-3Љ and C-5Љ), 140.04 (C-1Љ), 169.04 (C᎐O);
MeOH); H-NMR (500 MHz, CDCl3) δ 0.88 (3 H, t, –NCH2-
᎐
1210
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212

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CH3, J = 7.0 Hz), 1.05 (3 H, t, H-3Ј, J3Ј,2Ј = 7.4 Hz), 1.15 (3 H,
t, –NCH2CH3, J = 7.0 Hz), 1.21 (1 H, ddd, H-2, J2,3a = 6.4,
cm2Ϫ1, and incubated at 37 ЊC for 24–36 h. They were then
incubated at 43 ЊC for 30–60 min and maintained at 37 ЊC for
6–18 h in an appropriate selective growth medium containing
1 mM DL-APV (Sigma), a specific competitive antagonist of
the NMDA receptor added to prevent toxicity due to possible
activation of the NMDA receptors.
J2,3b = 9.0, J2,1Ј = 9.0 Hz), 1.43 (1 H, dd, H-3a, J3a,3b = 6.0, J3b,2
6.4 Hz), 1.72–1.89 (2 H, m, H-2Ј), 2.25 (1 H, dd, H-3b, J3b,3a
=
=
6.0, J3b,2 = 9.0 Hz), 2.69 (3 H, s, –NH–Me), 2.84 (1 H, m, H-1Ј),
3.37 (1 H, m, –NCH2CH3), 3.43–3.52 (3 H, m, –NCH2CH3),
7.27–7.39 (5 H, m, aromatic); 13C-NMR (125 MHz, CDCl3)
δ 10.21 (C-3Ј), 12.49 (–NCH2CH3), 13.10 (–NCH2CH3), 19.00
(C-3), 24.03 (C-2Ј), 29.38 (–NH–Me), 31.91 (C-2), 34.50 (C-1),
41.07 (–NCH2CH3), 43.67 (–NCH2CH3), 64.18 (C-1Ј), 126.78
(C-2Љ and C-6Љ), 128.52 (C-4Љ), 130.24 (C-3Љ and C-5Љ), 140.01
Measurement of [Ca2؉]i with the CHO cells
The CHO cells were incubated for 45 min with 5.0 µM fura-
2-AM (Dojindo, Kumamoto, Japan), dispersed by brief soni-
cation in a balanced salt solution (BSS), consisting of 130 mM
NaCl, 5.4 mM KCl, 2.0 mM CaCl2, 5.5 mM glucose and 10 mM
HEPES (pH 7.3), supplemented with 0.001% cremophore EL
(a solubility enhancer; Sigma). The fura-2-loaded cells were
then placed on the stage of an inverted fluorescence microscope
(IX50; Olympus, Tokyo, Japan) and perfused with BSS at a
rate of 2.0 mL minϪ1. Using alternate illumination at 340 and
380 nm excitation, fluorescence images were obtained using a
magnification objective lens (UApo 20x/340; Olympus) and an
emission filter (510–550 nm).The images were captured using a
silicon-intensified-target video camera (C2400–8; Hamamatsu
Photonics, Hamamatsu, Japan) and digitized using an image
processor (Argus 50/CA; Hamamatsu Photonics). Finally, the
data were fed into a personal computer (Venturis FXs, Digital).
For ratiometry, ratio images were obtained by dividing the
fluorescence intensity at 340 nm excitation (F340) by that at
380 nm excitation (F380) using the computer and the image
processor.
(C-1Љ), 172.89 (C᎐O); HR-MS (EI) 288.2210 (Mϩ, C H N O
᎐
18 28
2
requires m/z 288.2202). Found: C, 66.31; H, 8.81; N, 8.58.
C18H29ClN2O requires C, 66.54; H, 9.00; N, 8.62%.
X-Ray crystallographic analysis of 15‡
C18H27ClN2O, M = 322.88, monoclinic, C2, a = 23.900 (4) Å, b =
6.065 (2) Å, c = 16.073 (3) Å, β = 128.08 (1)Њ, V = 1833.8 (7) Å3,
Z = 4, Dx = 1.169 Mg cmϪ3. Cell parameters were determined
and refined from 24 reflections in the range 26.5Њ < θ < 30.0Њ.
A colorless crystal (0.30 × 0.25 × 0.15 mm) was mounted
on a Mac Science MXC18 diffractometer with graphite-
monochromated Cu-Kα radiation (λ = 1.54178 Å). Data collec-
tion using the ω/2θ scan technique gave 1620 reflections at room
temperature, 1513 unique, of which 1508 with I > 0.00σ(I )
reflections were used in calculations. The intensities were cor-
rected for Lorentz and polarization factors, and for absorption
and extinction effects. The structure was solved by the direct
method and refined by the full-matrix least squares technique
using maXus (version 2.0) as the computer program. The non-
hydrogen atoms were refined anisotropically. All hydrogen
atoms were refined isotropically. The unweighted and weighted
values were 0.024 and 0.055, respectively. There was no peak
above 0.10 eÅϪ3 in the last Fourier-difference map.
Concentration–inhibition curves were fitted by the logistic
equation:
I/Icontrol = 1/{1 ϩ ([antagonist]/IC50)n},
(1)
where Icontrol is the response in the absence of the antagonist,
IC50 is the concentration of the drug that inhibits 50% of this
response and n is the Hill coefficient.
Binding assay on NMDA receptors
The binding affinity for the NMDA receptor was carried out
according to previously reported methods.15
Acknowledgements
This investigation was supported by a Grant-in-Aid for
Creative Scientific Research (13NP0401) from the Japan
Society for Promotion of Science. We are grateful to Daiso Co.,
Ltd. for the gift of chiral epichlorohydrins and also to Ms H.
Matsumoto, A. Maeda, S. Oka, and N. Hazama (Center
for Instrumental Analysis, Hokkaido University) for technical
assistance with NMR, MS, and elemental analysis.
Inhibitory effects on the uptake of 5-HT
The assay was carried out according to the previously reported
method.11
Cell culture and heat-induction of NMDA receptors subtypes
The CHO cell lines introduced expression vectors carrying
GluRζ1 and GluRε1, GluRε2, GluRε3, or GluRε4 subunit
cDNAs under the promotion of the Drosophila heat-shock pro-
tein HSP70 which was established as described previously.16 The
CHO cells expressing GluRε1/ζ1 and GluRε2/ζ1 subtypes were
maintained at 37 ЊC in eRDF-1 medium (1 : 1 : 2 mixture of
Dulbecco’s modified Eagle’s medium, Ham’s Nutrient Mixture
F-12 and RPMI1640, without -glutamate, glycine and -
aspartate) supplemented with 10% fetal bovine serum (FBS)
(Gibco BRL/Life Technologies, Inc., Grand Island, NY),
400 µg mLϪ1 geneticin (Sigma, St. Louis, MO), 2 µg mLϪ1
blasticidin S hydrochloride (Funakoshi, Tokyo, Japan), and
10 µg mLϪ1 puromycin (Sigma) in a humidified atmosphere
containing 5% CO2. The CHO cells expressing GluRε3/ζ1 and
GluRε4/ζ1 subtypes were maintained in eRDF-1 medium
supplemented with 10% FBS, 1200 µg mLϪ1 geneticin and 2 µg
mLϪ1 blasticidin S hydrochloride. For heat-induction of
NMDA receptors, the CHO cells were plated on collagen-
coated glass coverslips with a silicon rubber wall (Flexiperm
Disc; Heraeus, Germany) at a density of 1.5–2.5 × 104 cells
References and notes
1 R. Dingledine, K. Borges, D. Bowie and S. Traynelis, Pharmacol.
Rev., 1999, 51, 7–61.
2 H. Bräuner-Osbornel, J. Egebjerg, E. O. Nielsen, U. Madsen and
P. Krogsgaad-Larsen, J. Med. Chem., 2000, 43, 2609–2645.
3 G. L. Collingridge, J. C. Watkins, The NMDA Receptor, IRL Press at
Oxford University Press, Oxford, UK, 1994.
4 (a) J. Willetts, R. L. Balster and J. D. Leander, Trends Pharmacol.
Sci., 1990, 11, 423–428; (b) M. D. Tricklebank, L. Singh, R. J. Oles,
C. Preston and S. D. Iversoen, Eur. J. Pharmacol., 1989, 167,
127–135; (c) M. A. Rogawski, Trends Pharmacol. Sci., 1993, 14,
325–331.
5 J. W. Olney, J. Labruyere and M. T. Price, Science, 1989, 244,
1360–1362.
6 (a) B. S. Meldrum, M. J. Croucher, S. J. Czuczwar, J. F. Collins, K.
Curry, M. Joseph and T. W. Stone, Neuroscience, 1983, 9, 925–930;
(b) M. J. Hogan, A. Gjedde and A. M. Hakem, J. Neurochem., 1992,
58, 186–191.
7 (a) T. Kutsuwada, N. Kashiwabuchi, H. Mori, K. Sakimura,
E. Kushiya, K. Araki, H. Meguro, H. Masaki, T. Mumanishi,
M. Arakawa and M. Mishina, Nature, 1992, 358, 36–41; (b) T.
Yamakura, H. Mori, H. Masaki, K. Shimoji and M. Mishina,
Neuroreport, 1993, 4, 687–690; (c) M. Raditsch, P. R. Ruppersberg,
T. Kuner, W. Günther, R. Schoepfer, P. H. Seeburg, W. Jahn and
V. Witzemann, FEBS Lett., 1993, 324, 63–66; (d ) D. J. Laurie
‡ CCDC reference number 176579. See http://www.rsc.org/suppdata/
p1/b1/b111540p/ for crystallographic files in .cif or other electronic
format.
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212
1211

View Article Online
and P. H. Seeburg, Eur. J. Pharmacol., 1994, 268, 335–345; (e)
T. Priestley, P. Laughton, J. Myers, B. Le Bourdelles, J. Kerby and
P. J. Whiting, Mol. Pharmacol., 1995, 48, 841–848; ( f ) H. Mori
and M. Mishina, Neuropharmacology, 1995, 34, 1219–1237; (g) N. J.
Sucher, M. Awobuluyi, Y.-B. Choi and S. A. Lipton, Trends
Pharmacol. Sci., 1996, 17, 348–355; (h) V. I. Ilyin, E. R. Whittemore,
J. Guastell, E. Weber and R. M. Woodward, Mol. Pharmacol., 1996,
50, 1541–1550; (i) A. L. Buller and D. T. Monaghan, Eur. J.
Pharmocol., 1997, 320, 87–94; (j) T. W. Butler, J. F. Blake, J. Bordner,
P. Butler, B. L. Chenaed, M. A. Collins, D. DeCosta, M. J. Ducat,
M. E. Eisenhard, F. S. Menniti, M. J. Pagnozzi, S. B. Sands, B. E.
Segelstein, W. Volberg, W. F. White and D. Zhao, J. Med. Chem.,
1998, 41, 1172–1184; (k) K. Taniguchi, K. Shinjo, M. Mizutani,
K. Shimada, Y. Ishikawa, F. S. Menniti and A. Nagahisa, Br. J.
Pharmacol., 1997, 122, 809–812; (l ) R. M. Schelkun, P. Yuen, K.
Serpa, T. M. Leonard and D. W. Lawrence, J. Med. Chem., 2000, 43,
1892–1897; (m) K. Williams, Mol. Pharmacol, 1993, 44, 851–859.
8 Mouse NMDA receptor subunits GluRζ1, GluRε1, GluRε2,
GluRε3, and GluRge4 correspond to NR1, NR2A, NR2B, NR2C,
and NR2D subunits of rat, respectively.
12 (a) S. Shuto, S. Ono, Y. Hase, N. Kamiyama, H. Takada, K.
Yamashita and A. Matsuda, J. Org. Chem., 1996, 61, 915–923;
(b) S. Ono, S. Shuto and A. Matsuda, Tetrahedron Lett., 1996, 37,
221–224; (c) S. Shuto, S. Ono, Y. Hase, N. Kamiyama and A.
Matsuda, Tetrahedron Lett., 1996, 37, 641–644; (d ) S. Shuto, S. Ono,
Y. Hase, Y. Ueno, T. Noguchi, K. Yoshii and A. Matsuda, J. Med.
Chem., 1996, 39, 4844–4852; (e) S. Shuto, S. Ono, H. Imoto,
K. Yoshii and A. Matsuda, J. Med. Chem., 1998, 41, 3507–3514;
( f ) T. Noguchi, K. Ishii, H. Imoto, Y. Otubo, S. Shuto, S. Ono,
A. Matsuda and K. Yoshii, Synapse, 1999, 31, 87–96; (g) Y. Kazuta,
S. Shuto and A. Matsuda, Tetrahedron Lett., 2000, 41, 5373–5377;
(h) S. Shuto, K. Yoshii and A. Matsuda, Jpn. J. Pharmacol., 2001,
85, 207–213; (i) Y. Kazuta, S. Shuto, H. Abe and A. Matsuda,
J. Chem. Soc., Perkin Trans. 1, 2001, 599–604.
13 The reaction of alcohols with a NaN3–PPh3–CBr4 system has been
known to give the corresponding azide derivatives via the SN2
reaction pathway: I. Yamamoto, M. Sekine and T. Hata, J. Chem.
Soc., Perkin Trans. 1, 1980, 306–310.
14 (a) J. Haywood-Farmer, Chem. Rev., 1974, 74, 315–350; (b) C. F.
Wilcox, M. M. Loew and R. Hoffmann, J. Am. Chem. Soc., 1973,
95, 8192–8193.
9 Compound ( )-1 had previously been called “midalcipran”.
However, since the clinical studies began, the name “milnacipran”
has generally been used for ( )-1.
15 E. J. Corey and P. L. A. Fuchs, Tetrahedron Lett., 1972, 36,
2369–3772.
10 (a) M. Briley, Drugs Future, 1986, 11, 21–23; (b) C. Moret,
M. Charveron, J. P. M. Finberg, J. Cozinier and M. Briley,
Neuropharmacology, 1985, 24, 1211–1219; (c) B. Bonnaud, H.
Cousse, G. Mouzin, M. Briley, A. Stenger, F. Fauran and J.-P.
Couzinier, J. Med. Chem., 1987, 30, 318–325; (d ) M. Ansseau,
P. Papart, B. Troisfontaines, F. Bartholome, M. Bataille, G. Charles,
M. Schittecatte, P. Darimont and J. M. Devoitille, Psycho-
pharmacology, 1994, 114, 131–137; (e) F. Artigas, CNS Drugs, 1995,
4, 79–89.
16 T. Asano, I. Ikegaki, S. Satoh, D. Mochizuki, H. Hidaka, Y. Suzuki,
M. Shibuya and K. Sugita, Br. J. Pharmacol., 1991, 103, 1935–1938.
17 S. Uchino, Y. Kudo, W. Watanabe, S. Nakajima-Iijima and M.
Mishina, Mol. Brain Res., 1997, 44, 1–11.
18 (a) J. M. Olney, Ann. Rev. Pharmacol. Toxicol., 1990, 30, 47–71;
(b) D. W. Choi, Neuron, 1998, 1, 623–634.
19 (a) R. Dingledine, C. J. Mcbain and J. O. Mcnamara, Trends
Pharmacol. Sci., 1990, 11, 334–338; (b) J. McCulloch, Br. J. Clin.
Pharmac., 1992, 34, 106–114; (c) E. R. Wood, T. J. Bussey and A. G.
Phillips, Neurosci. Lett., 1992, 145, 10–14; (d ) S. A. Lipton, Trends
Neurosci., 1993, 16, 527–532.
11 S. Shuto, H. Takada, D. Mochizuki, R. Tsujita, Y. Hase, S. Ono,
N. Shibuya and A. Matsuda, J. Med. Chem., 1995, 38, 2964–2968.
1212
J. Chem. Soc., Perkin Trans. 1, 2002, 1199–1212