Synthesis and biological evaluation of 18-methoxycoronaridine congeners. Potential antiaddiction agents

Article abstract of DOI:10.1021/jm020562o

Variation of the methoxycarbonyl and C-18 substituents of the antiaddictive compound 18-methoxycoronaridine, and contraction of its isoquinuclidine ring segment, provided 15 congeners for SAR evaluation at opioid and α3β4 nicotinic acetylcholine receptors

Full text of DOI:10.1021/jm020562o

2716
J . Med. Chem. 2003, 46, 2716-2730
Syn th esis a n d Biologica l Eva lu a tion of 18-Meth oxycor on a r id in e Con gen er s.
P oten tia l An tia d d iction Agen ts
Martin E. Kuehne,*,† Liwen He,† Patrick A. J okiel,† C. J . Pace,‡ M. W. Fleck,‡ I. M. Maisonneuve,‡
Stanley D. Glick,‡ and J ean M. Bidlack§
Department of Chemistry, University of Vermont, Burlington, Vermont 05405, Center for Neuropharmacology and
Neuroscience, Albany Medical College, MC-136, Albany, New York 12208, and Department of Pharmacology and Physiology,
School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642-8711
Received December 19, 2002
Variation of the methoxycarbonyl and C-18 substituents of the antiaddictive compound 18-
methoxycoronaridine, and contraction of its isoquinuclidine ring segment, provided 15 congeners
for SAR evaluation at opioid and R3â4 nicotinic acetylcholine receptors. The opioid activities
were relatively low, and the R3â4 nicotinic acetylcholine receptor activities were found to
correlate with in vivo antiaddictive activities.
In tr od u ction
While the natural product ibogaine (1) has been the
subject of extensive studies with respect to its potential
activity as an antiaddiction agent1,2 and has even been
clinically used, its stimulant and hallucinogenic activity
and particularly its toxicity, manifested by tremors and
its demonstrated destruction of Pukinje cells in the
brain, exclude this alkaloid from consideration as a safe
drug for the treatment of addiction to substance abuse
(Figure 1).
F igu r e 1. Compounds with established antiaddiction activity.
uncertain for a long time. Recently, however, using
patch clamp methodology, 18-MC (3) was found to be a
relatively selective antagonist at R3â4 nicotinic recep-
tors, and it is now believed that this is 18-methoxycoro-
naridine’s major mode of action.12 Evidence pointing to
the importance of this action was provided by data
showing that low-dose combinations of 18-methoxycoro-
naridine (3) with other drugs known to have this same
With the observation that the related ester alkaloids
voacangine, voacristine, and conopharyngine are not
tremorigenic3 and with our finding that racemic coro-
naridine (2) also has some antiaddictive activity in rats,4
we launched a program of total synthesis to seek
nontremorigenic structural variants of coronaridine
having increased antiaddiction potency.5 The best of our
initial five coronaridine congeners,5a each with terminal
oxygen substitution of the coronaridine ethyl group, was
found to be 18-methoxycoronaridine (18-MC, 3).6 This
compound showed good activity in overcoming demand
for morphine,7,8 cocaine,7 alcohol,9 methamphetamine,10
and nicotine10 in habituated rats, without affecting
demand for water. It was found to be more potent than
its major metabolite 18-hydroxycoronaridine (4,5,11 al-
bifloranine), the corresponding benzyl ether 5,5 or the
MEM ether, or the acetate and lauryl ester derivatives
of albifloranine.5
Since the methyl ester substituent in those initial five
compounds was effective in elimination of tremorige-
nicity, it became important to determine if other cor-
responding ester, amide, or acid congeners of 18-MC
would also support this protection from neurotoxicity
and maintain the antiaddictive effect of 18-MC.
Although it could be shown that 18-methoxycoronari-
dine (3) reduces dopamine release in the nucleus ac-
cumbens7 and binds with low affinity to several types
of receptors,1,6 its precise mechanism of action has been
action (e.g., mecamylamine13 and dextromorphan14
)
decreased both morphine and methamphetamine self-
administration in rats at doses that were ineffective
when administered alone. Not only were combinations
of 18-MC with each of these agents effective, but a
dextromorphan-mecamylamine combination was simi-
larly effective. Because there are no agents available
that are entirely specific for R3â4 receptors, the use of
combinations of low doses of unrelated agents that act
at this site was thought to be a potentially practical way
of enhancing therapeutic efficacy (attributable to addi-
tive effects at the R3â4 site) while reducing side effects
(attributable to the actions unique to each agent).
Resu lts a n d Discu ssion
In the present study, a series of coronaridine conge-
ners was evaluated using patch clamp methodology to
determine their key antagonist activity at R3â4 nicotinic
receptors relative to the activity of 18-methoxycoronari-
dine (3) and to correlate this activity with in vivo
antiaddiction activity. For comparison, activities at
opioid receptors were measured.
Ch em istr y. For syntheses of new carbonyl deriva-
tives of 18-MC, the latter compound had to be converted
first to the corresponding carboxylic acid.Vigorous hy-
* To whom correspondence should be addressed. Telephone: 802
656 0272. Fax: 802 656 8705. E-mail: mkuehne@zoo.uvm.edu.
† University of Vermont.
‡ Albany Medical College.
§ University of Rochester.
10.1021/jm020562o CCC: $25.00 © 2003 American Chemical Society
Published on Web 05/08/2003

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2717
Sch em e 1
drolysis of the tertiary ester 3 resulted in its decar-
bomethoxylation. Consequently, the ester was demeth-
ylated by treatment with lithium 1-propanethiolate. The
resulting lithium salt 6 has low solubility in water, but
it could be converted to the corresponding water-soluble
sodium salt 7 by ion-exchange chromatography for
biological evaluation.
aldehyde 24 (92%). For protection as an acetal, the
methodology of Chan,15 with trimethylsilyl chloride and
ethylene glycol, was used (90%). Hydroboration of the
olefin 25 with disiamylborane avoided the formation of
a minor secondary alcohol product, which could not be
detected by NMR in alcohol 26 (95%). Hydrogenolysis
t
of the benzyl substituent (27, 79%) and BOC carbamate
formation with di-tert-butyl dicarbonate (28, 99%) was
followed by another Swern oxidation (99%). The result-
ing aldehyde 29, on condensation with the indoloazepine
30,16 neat at 130 °C, provided the key tetracyclic
intermediate 31 as a mixture of C-20 epimers in 93%
yield.
Generation of new ester and amide derivatives was
then obtained by treatment of the lithium salt 6 with
oxalyl chloride and reaction of the resulting acid chloride
with the respective sodium alcoholates, or with amines,
to furnish the esters 8-11 and amides 12-15. Carbam-
ate cleavage of the BOC derivative 15 provided the
corresponding amine 16. A reaction of the latter with
(+)-biotin 4-nitrophenyl ester gave the biotinylated
product 17a ,b as a mixture of two diastereomers. These
could be separated on a chiral ODS HPLC column into
the respective diastereomers 17a and 17b (Scheme 1).
An alternative to the 18-MC structure, which would
maintain its skeleton and allow extensive variation of
the key C-18 substitution, was expected for 18-ami-
nocoronaridines. Such compounds, 18 and 19, were
generated by total synthesis (Schemes 2 and 3).
Alkylation of diethyl allylmalonate with dibromoeth-
ane provided the bromoethylmalonate 20 in 81% yield.
Its reaction with N-benzylmethylamine gave the diester
amine 21 in 56% yield. A Krapcho decarboethoxylation
generated the monoester 22 in 97% yield. Reduction of
the ester 22 with lithium aluminum hydride to the
alcohol 23 (98%) and Swern oxidation furnished the
Reductive cleavage of the tetracyclic intermediate 31
with sodium borohydride in hot acetic acid gave the
indoloazonines 32 (1H NMR δ 5.6 for C-16 H) ac-
companied by about 10% of the C-16 ester epimeric
product (1H NMR δ 5.1 for C-16 H, total 93% yield).
Hydrogenolysis of the N-benzyl substituent led to the
C-20 epimeric but C-16 unique secondary amines 33
(94%). Epimerization of the methoxycarbonyl group
under acidic conditions had been observed in our previ-
ous syntheses.5,17 For cyclization to the enamine 34, it
t
was necessary to preserve the BOC substituent in the
hydrolysis of the acetal function of intermediates 33.
At -10 °C, this hydrolysis with 10% HCl in acetonitrile
was slow but selective, forming on workup the enamine
34 in 91% yield. Its rearrangement on heating in
benzene for 12 h gave the coronaridine congener 35 in
53% yield. Cleavage of the carbamate substituent with

2718 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
Sch em e 2a
Sch em e 4a
a
Reagents and conditions: (a) NaH, THF, Br(CH2)2Br, 81%;
(b) Me(Bn)NH, K2CO3, acetone, 36 h reflux, 56%; (c) LiCl, DMSO/
DMF, 190 °C, 6 h, 97%; (d) LAH, ether, 98%; (e) (COCl)2, DMSO,
-78 °C, then Et3N, -78 °C, 10 h, 92%; (f) ethylene glycol, TMSCl,
CH2Cl2, 72 h reflux, 90%; (g) disiamylborane, THF, -10 °C, 3 h,
then H2O2, NaOH, 95%; (h) H2, Pd/C, HOAc, 79%; (i) BOC2O,
CH2Cl2, 99%; (j) (COCl)2, DMSO, then Et3N, 92%; (k) 135 °C, neat,
30 min, 93%.
a
Reagents and conditions: (a) OsO4 (cat.), NaIO4, room temp,
24 h (90%); (b) neat, 130 °C, 1 h (76%); (c) NaBH4, HOAc, 90 °C,
20 min (63%); (d) 10% Pd/C, H2, HOAc (95%); (e) 10% HCl/CH3CN,
room temp, 45 min (94%); (f) toluene, reflux 24 h (64%).
isoquinuclidine core of 18-MC (3) is essential for its
biological activity or if a [2.2.1] bridged compound 36
would still be active.This compound could be obtained
(Scheme 4), starting from oxidative cleavage of the
olefinic 18-MC precursor 37 (90%).5 Condensation of the
resulting aldehyde 38 with the melted indoloazepine 30,
at 130 °C, gave a 1:1 diastereomeric mixture of tetra-
cyclic methoxyethyl epimers 39 in 76% yield.
Sch em e 3a
On reductive cleavage with sodium borohydride in hot
acetic acid, these tetracycles furnished a 6:1 ratio of
trans/cis substituted indoloazonines 40 and 41 (63%).
1
The H NMR signal of the hydrogen R to the methoxy-
carbonyl group is shifted downfield (δ 5.58) in the major
epimer 40 relative to that in the minor epimer 41 (δ
4.57) because of proximity of the former hydrogen to Nb.
Debenzylation (95%) of the indoloazonines by hydro-
genolysis in acetic acid, with concomitant epimerization
of the minor precursor 41, gave the secondary amine
C-20 diastereomers 42 (95%). Acetal hydrolyis with
aqueous HCl in acetonitrile and workup produced the
enamine 43 in 94% yield.
Of particular interest in this synthesis was the
cyclization of the enamine 43 by a thermal electrocyclic
rearrangement. In comparison to formation of the [2.2.2]
bicyclic core of 18-MC, formation of the [2.2.1] ring
system would be expected to increase ring strain. The
rearrangement was found to be slow, taking 24 h in
refluxing toluene to produce the 18-MC congener 36 in
64% yield.
a
Reagents and conditions: (a) NaBH4, HOAc, 90 °C (93%); (b)
H2, Pd/C, HOAc (94%); (c) CH3CN, 10% HCl, -10 °C, 72 h (91%);
(d) benzene, reflux 12 h (53%); (e) HCl, MeOH, reflux 4 h (93%);
(f) (1) CH2O, MeOH, reflux 1 h, (2) NaBH4 (45%).
methanolic HCl then provided the secondary amine 18
(93%). On reductive alkylation with formaldehyde and
sodium borohydride, the 18-dimethylaminocoronaridine
19 was obtained.
With the syntheses of 18-MC congeners with varia-
tions of the ester and side chain substitution and their
evaluation as potential antiaddiction agents (see below),
it became of interest to see if the [2.2.2] bridged

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2719
Ta ble 1. Percent Inhibition of µ, δ, and κ Opioid Binding to
Guinea Pig Brain Membranes by 1 µM of the Following
Compoundsa
Ta ble 2. Inhibition of R3â4 Nicotinic Acetylcholine Receptor
Bindinga
rate of
%
% inhibition ( SE
compd
% inhibition inhibition (s-1
)
recovery
n
RI
0.25 nM
0.2 nM
1 nM
3 (18-MC)
4
5
7
8
9
10
11
12
13
14
18
19
36
a
98 ( 0
98 ( 1
64 ( 7
59 ( 1
98 ( 2
97 ( 1
95 ( 3
99 ( 0
93 ( 3
85 ( 3
96 ( 1
98 ( 1
99 ( 1
94 ( 3
5.5 ( 0.4
6.5 ( 0.7
2.2 ( 0.3
5.1 ( 0.1
10.3 ( 2.5
7.6 ( 0.7
6.7 ( 1.6
6.0 ( 0.5
9.5 ( 0.7
7.9 (0.7
9.2 ( 0.9
8.5 ( 1.9
8.0 ( 2.4
4.1 ( 0.8
12 ( 3
73 ( 1
0 ( 0
27 ( 10
16 ( 10
20 ( 3
45 ( 4
8 ( 4
81 ( 5
80 ( 16
46 ( 9
21 ( 3
16 ( 3
14 ( 5
6
5
3
4
3
4
3
6
5
5
5
5
3
4
1.0
5.4
na
compd [3H]DAMGO (µ) [3H]naltrindole (δ) [3H]U69,593 (κ)
3
4
5
6
8
9
50 ( 6
15 ( 3
12 ( 0
11 ( 1
16 ( 0
8 ( 5
0 ( 16
5 ( 2
4 ( 1
7 ( 1
10 ( 0
19 ( 4
24 ( 1
15 ( 2
18 ( 4
35 ( 6
14 ( 2
8 ( 3
3 ( 3
28 ( 2
9 ( 1
20 ( 2
4 ( 1
6 ( 4
7 ( 4
78 ( 1
8 ( 2
3 ( 1
24 ( 1
11 ( 2
9 ( 2
6 ( 1
9 ( 5
7 ( 0
11 ( 1
10 ( 2
2.4
0.7
1.2
3.1
0.6
3.9
4.7
2.3
1.1
0.9
1.6
10
11
12
13
14
17a ,b
18
19
36
10 ( 0
11 ( 1
14 ( 2
10 ( 1
7 ( 2
9 ( 2
For methodology, see ref 12.Values are the mean ( SEM for
inhibition of 1 mM ACh-evoked responses. Drug concentrations
were 20 µM except for compound 4, which was 18 µM. Ki for 18-
methoxycoronaridine (3) is 0.7 µM as determined from kinetic
measures of koff/kon. The relative inhibition index (RI) was calcu-
lated as the percent recovery/(rate of inhibition) and is expressed
relative to 18-methoxycoronaridine (3). RI values less than 1.0
reflect lower Ki (more potent), and RI values greater than 1.0
reflect higher Ki (less potent). Vehicle alone, including 1% DMSO,
did not produce any inhibition.
55 ( 5
49 ( 1
19 ( 4
a
For control data, see ref 18. Guinea pig brain membranes, 0.5
mg of protein/sample, were incubated with 1 µM of the compounds
in the presence of receptor-specific radioligands at 25 °C in a final
volume of 1 mL of 50 mM Tris-HCl, pH 7.5. Nonspecific binding
was determined using 10 µM naloxone. Data are the mean value
( SE from three separate experiments performed in triplicate.
Biologica l Eva lu a tion . a . Op ioid Recep tor s. Like
ibogaine, 18-MC (3) showed low micromolar affinity for
the three opioid receptors (µ, δ, κ) with Ki(µ) ) 1.1, Ki(δ)
) 3.5, and Ki(κ) ) 5.1 µM.7b Modest opioid binding
inhibition by the present congeners of 18-MC (Table 1)
further supports the view that these compounds, as a
class, derive their antiaddiction potential from a differ-
ent mechanism of action. Only the dimethylaminoethyl
ester 8 stood out with its maximum 78% binding
inhibition for the κ opioid receptor, at 1 µM concentra-
tion.
Because compound 8 produced 78% inhibition of
binding to the κ opioid receptor, it was titrated and a
Ki value was determined. Twelve different concentra-
tions of compound 8 were titrated against 1 nM [3H]-
U69,593. Compound 8 had a Ki value of 188 ( 19 nM
for binding to the κ opioid receptor. This compound has
the highest affinity for the κ receptor. For comparison,
Ki values, obtained by the same methodology for U50,-
488, EKC, cyclazocine, and levorphanol, have been
reported.18
Biologica l Eva lu a tion . b. r3â4 Nicotin ic Acetyl-
ch olin e Recep tor Bin d in g Stu d ies. HEK293 cells
expressing R3 and â4 subunits of nicotinic acetylcholine
(ACh) receptors were voltage-clamped to -70 mV and
examined by whole-cell patch clamp recording with fast
perfusion of ACh and drug solutions. Application of 1
mM ACh produced a large inward current, which turned
on and off rapidly and was present for the length of the
ACh pulse (Figures 2 and 3). However, the magnitude
of the current decreased slowly with persistent applica-
tion of agonist. This desensitization is common for
neurotransmitter receptor currents. Coapplication of 20
µM 18-MC (3) produced a rapid and nearly complete
inhibition (98% on average) of the ACh-evoked currents
(Figure 2A), which recovered slowly and only partially
(12 ( 3%) within 1 s after the removal of 18-MC. This
is consistent with our previous studies showing that
ibogaine and 18-MC potently inhibit ACh evoked cur-
rents at R3â4 receptors.12
To extend these findings, we tested a series of 18-
MC congeners for inhibition of ACh-evoked currents at
R3â4 receptors. Results are presented in Figure 2, and
a summary of these findings is given in Table 2. Of the
13 compounds tested, all inhibited the inward currents
produced by application of ACh; however, they differed
in their potencies (Figure 2B). The esters 8, 9, 11, 18,
19, and 36 in particular were very potent. On average,
each of these compounds inhibited ACh evoked currents
by greater than 94% while the currents slowly recovered
less than 25% when the drug was removed. Of these,
compounds 8, 9, and the 18-amino coronaridines 18 and
19 had fast inhibition rates ranging from 7.6 to 10.3 s-1
.
The ester 11 had a somewhat slower inhibition rate of
6.0 s-1, whereas the compound with a ring-contracted
isoquinuclidine, 36, was considerably slower at 4.1 s-1
.
The ester bearing an amide substituent, 10, and the 18-
MC amide derivatives 12-14 inhibited the ACh evoked
currents by 85% or more; however, the currents recov-
ered by more than 45% when the drug was removed.
These compounds had relatively fast inhibition rates
ranging from 6.7 to 9.5 s-1, suggesting that they bind
rapidly to the receptors, whereas their fast recovery
suggests they also unbind rapidly, accounting for the
reduced overall level of inhibition. Finally, the benzyl
ether 5 and the sodium salt 7 corresponding to 18-MC
inhibited the ACh-evoked currents by less than 65%;
both were relatively slow to block, but they differed in
the rate of block (2.2 and 5.1 s-1) and the extent of
recovery at 1 s after removal of the compounds.
The nature of the inhibition assay is such that
supersaturating drug concentrations must be used to
measure inhibition during the agonist application. The
rate of drug binding and inhibition (kon) is concentration-
dependent and, for practical reasons, must be main-
tained at a faster rate than the natural decay of the
ACh-evoked response that occurs by desensitization.
The 20 µM concentration was selected as appropriate
on the basis of 18-methoxycoronaridine (3) inhibition
kinetics (note the IC50 for parent congener 3 is less than

2720 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
F igu r e 2. Inhibition of nicotinic R3â4 receptors by 18-methoxycoronaridine (18-MC) and 18-MC-like compounds. Recombinant
receptors were expressed in HEK293 cells and examined by whole-cell patch clamp recordings with rapid application of acetylcholine
(ACh) and drug solutions. (A) Whole-cell current evoked by application of 1 mM ACh in transfected cells was nearly eliminated
by coapplications of 20 µM 18-MC. Current traces for the control and drug co-application are superimposed. Open bar depicts the
timing of ACh application. Solid bar depicts the timing of coapplication of 18-MC. Arrows point to measurements presented in
Table 2. (B) Inhibition of 1 mM ACh-evoked currents by various 18-MC like compounds. Conventions are as in part A. Horizontal
scale bar applies to all traces. Vertical bars are 0.5 nA for all traces.
1 µM). Our goal in these studies was to gauge the
relative potencies of the congeners in comparison to 18-
methoxycoronaridine. Relative effective concentrations
of 18-methoxycoronaridine and the various congeners
can be inferred from the data in Table 2, where the more
potent congeners produce nearly 100% inhibition, in-
hibit more quickly, and/or recover less completely than
the parent 3.
F igu r e 3. Controls for experiments shown in Figure 2.
It is possible kinetically to estimate the equilibrium
inhibition constants (Ki) for these compounds from the
equation
some of them; this was particularly true for the most
promising compounds, i.e., compounds 8, 9, 11, 18, and
19. To facilitate comparisons between the drugs, Table
2 gives a relative inhibition index (RI) that was calcu-
koff
Ki ) [drug]
kon
lated as the percent recovery/rate of inhibition (similar
to koff/kon) and that reflects the altered affinities of the
congeners relative to 18-methoxycoronaridine (i.e., for
18-MC, 3, it is 1).
Several of the congeners (depending on the amounts
available) were subsequently tested on morphine self-
administration in rats using well-established proce-
dures.7a,12 Nine compounds were examined, all admin-
istered (ip) at 20 mg/kg (a dose at which 18-methoxy-
coronaridine (3) reduces morphine self-administra-
tion to 40% of baseline). All of these compounds signifi-
cantly reduced morphine self-adminstration (Ns ) 4-6;
where koff is given by the rate of recovery and kon is given
by the rate of inhibition. The IC50 for 18-methoxycoro-
naridine (3) is approximately 0.75 µM,12 close to the Ki
estimate (0.67 mM) obtained from measurements of koff/
kon at 20 µM drug. The congeners showing the least
recovery following their removal are generally expected
to have lower Ki values reflecting their slower unbinding
from the nicotinic receptor. However, we did not esti-
mate Ki values for all of the congeners in part because
recovery time constants were too slow to resolve for

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2721
publication. The new procedures for those two compounds
follow below.
p < 0.05-0.001). Of the nine compounds, five (18-
methoxycoronaridine (3), 8, 11, 18, 19) had relatively
high nicotinic affinities (RI ) 0.86 ( 0.09) and four (4,
10, 13, 36) had relatively low nicotinic affinities (RI )
3.70 ( 0.85). The higher affinity compounds had a
significantly larger effect than the lower affinity com-
pounds (for morphine self-administration, percent of
baseline is 35.0 ( 4.8 vs 65.0 ( 11.5; p < 0.04). In
addition, four of the higher potency compounds were
tested at a dose of 5 mg/kg, which is less than the
minimally effective dose of 18-methoxycoronaridine
(3).7a The most potent compound, and the only one
producing a significant effect at 5 mg/kg, was the
methoxyethyl ester 11. Compound 11 also had the
highest affinity index (RI, from Table 2).19
The pharmacokinetics of 18-methoxycoronaridine (3)
have been previously studied.7b The compound appears
to be sequestered in fat and slowly released. Concentra-
tions of 18-methoxycoronaridine in discrete brain re-
gions have not been determined, so it is difficult to
definitively determine whether the affinity of 18-meth-
oxycoronaridine at this nicotinic site is pharmacologi-
cally relevant to its antiaddictive property. However,
relative to the many other receptor sites examined,7b,12
18-methoxycoronaridine appears to be most potent at
the R3â4 nicotinic site.
All reactions were carried out under nitrogen or argon. NMR
spectra were obtained with a Bruker 500 MHz instrument.
Mass spectrometry was performed with a Finnegan 4610
quadrupole instrument. IR spectra were obtained using a
Perkin-Elmer system 2000 FT-IR instrument. TLC was per-
formed on Art. 5554 DC-Alufolien Kieselgel 60 F254 silica gel
on aluminum sheets and developed with ceric ammonium
sulfate (CAS) or phosphomolybdic acid (PMA) spray reagents.
For flash chromatography, 60-200 mesh silica gel was used.
HPLC data were obtained with Star Chromatography Work-
station, version 5.50, using a ProStar/Dynamax (2 v) detector
and aVarian Microsorb-MV 100 Å C5 silica column or an
ASTEC Cyclobond I 2000 (cyclodextrins linked to silica)
column.
4-(1,3-Dioxola n -2-yl)-6-m eth oxyh exa n -1-ol (10b).5a To a
stirred solution of borane-THF (1 M, 8.1 mL, 8.1 mmol) at
-10 °C, was added, dropwise, a solution of 2-methyl-2-butene
in THF (2 M, 8.1 mL, 16.2 mmol) over 30 min. The mixture
was stirred for 3 h at -10 °C. A solution of 4-(1,3-dioxolan-2-
yl)-6-methoxy-1-hexene (1.0 g, 5.4 mmol)5a in dry THF (20 mL)
was added dropwise over 10 min at -10 °C, and the mixture
was stirred for 2 h at 0 °C. Then 15% NaOH (2.2 mL, 8.3 mmol)
and 30% H2O2 (2.20 mL, 19.4 mmol) were added dropwise. The
reaction mixture was heated at reflux for 1 h, cooled to room
temperature, and concentrated under reduced pressure. To the
residue was added saturated NH4Cl solution (50 mL). Extrac-
tion with dichloromethane (4 × 30 mL), washing of the
combined organic layers with saturated brine (2 × 30 mL),
drying over MgSO4, concentration under reduced pressure, and
chromatography on a silica gel column, eluting with hexane/
ethyl acetate (1:4), gave the title compound 10b (1.04 g, 95%).
Con clu sion
A comparison of 18-methoxycoronaridine (3), cur-
rently being advanced as a potential treatment for
multiple forms of drug abuse, with 13 congeners for the
key activity as antagonists at R3â4 nicotinicacetylcho-
line receptors, indicated that the coronaridine meth-
oxycarbonyl group can be replaced by other ester
functions with retention of similar levels of activity.
The corresponding amides showed relatively fast
binding but also fast unbinding from this receptor.
The carboxylic acid, administered as its sodium salt
7, was the least active compound in the R3â4 nicotinic-
acetylcholine receptor assay.
Replacement of the 18-methoxy substituent of 18-
methoxycoronaridine by a dimethylamine amine func-
tion (19) provided high R3â4 inhibition at a relatively
fast rate and slow recovery.
The ring-contracted isoquinuclidine 36 showed a
slight drop in R3â4 percent inhibition relative to 18-
methoxycoronaridine (3).
18-Methoxycoronaridine (3) behaves neither as an
agonist nor as an antagonist at opiate receptors.3 We
showed that 18-methoxycoronaridine shifts the whole
morphine self-administration dose-response curve lower8
rather than to the left or to the right, as would be
expected of an agonist or antagonist, respectively (i.e.,
18-methoxycoronaridine (3) reduces the efficacy of
morphine). Consistent with the opiate data presented
here, there is no evidence that 18-methoxycoronaridine
and related congeners work in vivo directly via an opiate
action, but their R3â4-nicotinic receptor binding is a
likely mechanism of their antiaddiction activity.
En a m in e (19b).5a Secondary amine acetal 18b5a (3.089 g,
7.2 mmol) was dissolved in acetonitrile (35 mL) and degassed,
and 10% HCl (35 mL) was degassed and transferred into the
above acetonitrile solution. Shielded from light, the mixture
was stirred for 4 h at room temperature under argon, then
poured into crushed ice, basified with 15% aqueous NH3, and
extracted with ether (7 × 150 mL). The extracts were dried
over powdered 4 Å molecular sieves for 30 min, concentrated,
then dried in a desiccator with P2O5 under vacuum overnight.
The crude enamine was used directly for thermal isomerization
to 18-methoxycoronaridine.
18-Meth oxyiboga m in e 16-Lith iu m ca r boxyla te (6). To
a solution of n-butyllithium in hexane (1.6 M, 6.80 mL, 10.9
mmol) in dry THF (40 mL) at 0 °C were added dropwise
1-propanethiol (1.20 mL, 13.3 mmol) and dry HMPA (1.80 mL,
10.4 mmol). After the mixture was stirred for 1 h at room
temperature, 18-methoxycoronaridine (3, 1.0 g, 2.7 mmol) in
dry THF (60 mL) was added. The mixture was stirred for 68
h at room temperature, water (0.25 mL, 14 mmol) was added,
and the mixture was concentrated at 32 °C under reduced
pressure. The residue was chromatographed on silica gel (SM/
silica gel ) 1:400), eluting with dichloromethane/methanol (2:
1) to give the title compound 6 (0.955 g, 98%) as a yellow
solid: mp 183-184 °C; TLC Rf ) 0.42 (silica gel, dichlo-
romethane/methanol, 2:1, CAS yellow); UV (EtOH) λmax 224,
284 nm; IR (KBr) νmax 3420, 3184, 2923, 1606, 1464, 1363,
1334, 1320, 1110, 1093, 1048, 1011, 979 cm-1 1H NMR
;
(DMSO-d6) δ 1.03-1.07 (m, 1 H), 1.58-1.77 (m, 6 H), 2.59 (d,
J ) 5 Hz, 1 H), 2.67 (d, J ) 5 Hz, 1 H), 2.67 (d, J ) 8 Hz, 1 H),
2.83 (m, 1 H), 2.95-3.03 (m, 3 H), 3.21 (s, 3 H), 3.32-3.37 (m,
4 H), 6.92 (t, J ) 8 Hz, 1 H), 6.98 (t, J ) 8 Hz, 1 H), 7.26 (d,
J ) 8 Hz, 1 H), 7.38 (d, J ) 8 Hz, 1 H), 10.34 (s, 1 H); 13C
NMR (DMSO-d6) δ 21.4, 26.9, 31.7, 32.7, 34.1, 35.6, 53.0, 53.3,
54.3, 56.8, 57.9, 70.1, 108.6, 111.1, 117.7, 120.6, 127.9, 135.6,
135.8, 138.4, 175.1; MS (CI), m/z (rel intensity) 367 (M+ + Li,
0.2), 355 (M+ - Li + 2, 0.48), 312 (1), 311 (4), 279 (0.5), 232
(100), 157 (4). Anal. (C21H25N2O3Li) C, H, N.
Exp er im en ta l Section
18-Meth oxyiboga m in e 16-Sod iu m ca r boxyla te (7). To a
solution of the lithium salt 6 (0.25 g, 0.69 mmol) in THF/HMPA
(1:1, 4 mL) was added Amberlite IR-120 (plus) ion-exchange
resin (sodium form), and the mixture was stirred for 0.5 h,
Ch em ica l Meth od ology. The synthetic route for 18-
methoxycoronaridine (3) was similar to that reported5a except
for the synthesis of intermediates 10b and 19b of that

2722 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
filtered, and concentrated at 32 °C under reduced pressure.
The residue was chromatographed on silica gel (SM/silica gel
) 1:400), eluting with dichloromethane/methanol (2:1) to give
the sodium salt 7 (0.21 g, 80%) as a yellow powder: mp 159-
160 °C; TLC Rf ) 0.42 (silica gel, dichloromethane/methanol,
2:1, CAS yellow); UV (EtOH) λmax 224, 284 nm; IR (KBr) νmax
174.6; MS (CI), m/ z (rel intensity) 412 (M+ + 1, 18), 411 (M+,
100). Anal. (C24H33N3O3) C, H, N.
18-Met h oxycor on a r id in e 2-Hyd r oxyet h yla m id e (13).
Following the above procedure, the reaction of the 18-meth-
oxycoronaridine-derived acid chloride with ethanolamine for
1.5 h at 0 °C, regular workup, and chromatography on silica
gel, eluting with ethyl acetate/methanol (25:1), gave compound
13 (82%) as a white solid: mp 205 °C (dec); TLC Rf ) 0.26
(silica gel, ethyl acetate/methanol, 25:1, CAS blue); UV (EtOH)
1
3409, 2925, 2362, 1606, 1462, 742 cm-1; H NMR (DMSO-d6
+ D2O) δ 1.03-1.04 (m, 1 H), 1.56-1.81 (m, 6 H), 2.55 (d, J )
13 Hz, 1 H), 2.63 (d, J ) 9 Hz, 1 H), 2.86 (d, J ) 9 Hz, 1 H),
2.94-3.05 (m, 3 H), 3.19 (s, 3 H), 3.29-3.37 (m, 4 H), 6.91(t,
J ) 7 Hz, 1 H), 6.98 (t, J ) 7 Hz, 1 H), 7.24 (d, J ) 8 Hz, 1 H),
λ
max 226, 286 nm; IR (KBr) νmax 3303, 2923, 1653, 1624, 1559,
1522, 1458, 1259, 1107, 742, 668 cm-1 1H NMR (CDCl3) δ
;
7.36 (d, J ) 8 Hz, 1 H), 10.23 (s, 1 H); 13C NMR (DMSO-d6
+
1.10-1.11 (m, 1 H), 1.61-1.64 (m, 1 H), 1.73-1.76 (m, 1 H),
1.82-1.85 (m, 1 H), 1.89-1.93 (m, 4 H), 2.82-2.86 (m, 2 H),
2.93-3.02 (m, 2 H), 3.06-3.15 (m, 1 H), 3.22-3.27 (m, 3 H),
3.33 (s, 3 H), 3.36-3.47 (m, 3 H), 3.56-3.68 (m, 4 H), 6.12 (s,
1 H), 7.08 (t, J ) 8 Hz, 1 H), 7.14 (t, J ) 8 Hz, 1 H), 7.23 (d,
J ) 8 Hz, 1 H), 7.46 (d, J ) 8 Hz, 1 H), 8.17 (s, 1 H); 13C NMR
(CDCl3) δ 22.3, 27.3, 32.2, 33.2, 33.6, 35.4, 42.9, 51.6, 53.5,
55.2, 58.1, 59.8, 61.5, 71.3, 110.1, 110.5, 118.3, 119.2, 122.1,
128.7, 135.7, 138.1, 175.3; MS (CI), m/ z (rel intensity) 398 (M+
+ 1, 25), 397 (M+, 100), 178 (19), 92 (12). HRMS calcd for
D2O) δ 21.5, 27.1, 31.8, 33.1, 34.2, 36.0, 53.5, 53.7, 54.5, 57.3,
58.3, 70.5, 108.9, 112.0, 118.0, 122.0, 128.3, 136.0, 136.1, 138.7,
176.0; MS (CI), m/ z (rel intensity) 356 (15), 355 (M+ - Na +
2, 100), 311 (21), 277 (7), 221 (10), 209 (11), 207 (15), 195 (17).
HPLC: (a) silica C5, 68 bar, 1 mL/min, hexane/2-propanol/
triethylamine (1:1:0.02), injection in 20 µL of THF, retention
time of 55.52 min; (b) Cyclobond I 2000, 146 bar, 3 mL/min,
hexane/ethanol/triethylamine (60:40:0.2), injection in 20 µL of
THF, retention time of 27.44 min.
C
23H31N3O3: 397.2365. Found: 397.2359. HPLC: (a) silica C5,
18-Met h oxycor on a r id in e N,N-Dim et h ylet h ylen ed i-
a m in e Am id e (12). The lithium salt 6 (0.10 g, 0.30 mmol)
was suspended in dry THF (15 mL), and dry pyridine (0.03
mL, 0.4 mmol) was added at 0 °C, followed by oxalyl chloride
(2 M, 0.6 mL, 1.2 mmol). The mixture was stirred for 42 h at
room temperature and concentrated at 32 °C. The acid chloride
residue was dissolved in dry dichloromethane (25 mL), and at
0 °C N,N-dimethylethylenediamine (0.3 mL, 2.6 mmol) was
added dropwise. The mixture was stirred for 1 h (0 °C to room
temperature), the organic phase was washed with water (3 ×
20 mL), the combined aqueous phases were extracted with
dichloromethane (3 × 30 mL), and the combined organic layers
were washed to neutral with brine, dried over sodium sulfate,
concentrated, and chromatographed on silica gel, eluting with
dichloromethane/methanol (2:1) to give the amide 12 (0.11 g,
87%) as a yellow solid: mp 69-70 °C; TLC Rf ) 0.26 (silica
gel, dichloromethane/methanol, 2:1, CAS blue); UV (EtOH) λmax
228, 286 nm; IR (KBr) νmax 3320, 2925, 2857, 1653, 1521, 1461,
1347, 1290, 1186, 1118, 740, 668 cm-1; 1H NMR (CDCl3) δ 1.10
(m, 1 H), 1.65-1.68 (m, 2 H), 1.78-1.90 (m, 4 H), 2.28 (s, 6
H), 2.32-2.36 (m, 1 H), 2.45-2.49 (m, 1 H), 2.87-2.92 (m, 4
H), 3.17-3.21 (m, 2 H), 3.30 (s, 3 H), 3.29-3.31 (m, 3 H), 3.41
(t, J ) 7 Hz, 2 H), 3.61-3.65 (m, 1 H), 5.91 (s, 1 H), 7.06 (dt,
J ) 7, 1 Hz, 1 H), 7.11 (dt, J ) 8, 1 Hz, 1 H), 7.22 (dd, J ) 8,
1 Hz, 1 H), 7.47 (d, J ) 8 Hz, 1 H), 9.18 (s, 1 H); 13C NMR
(CDCl3) δ 21.9, 27.1, 31.6, 33.4, 34.5, 35.6, 37.5, 45.4, 50.7,
53.5, 55.7, 58.45, 58.47, 60.8, 71.4, 110.6, 110.9, 118.2, 119.0,
121.7, 129.0, 135.8, 139.5, 174.3; MS (CI), m/ z (rel intensity)
426 (M+ + 2, 10), 425 (M+ + 1, 100), 392 (3), 255 (7), 114 (4),
88 (4). HRMS calcd for C25H36N4O2Li: 431.2998. Found:
431.2997. HPLC: (a) silica C5, 39 bar, 1 mL/min, hexane/2-
propanol/triethylamine (4:1:0.05), injection in 20 µL of 2-pro-
panol, retention time of 13.16 min; (b) Cyclobond I 2000, 96
bar, 2 mL/min, hexane/ethanol (6:4), injection in 20 µL of
ethanol, retention time of 9.05 min.
34 bar, 1 mL/min, hexane/2-propanol/triethylamine (9:1:0.1),
injection in 20 µL of 2-propanol, retention time of 11.11 min
(97.6% purity), retention time of 13.74 min (2.4% impurity);
(b) Cyclobond I 2000, 32 bar, 1 mL/min, hexane/ethanol (9:1),
injection in 20 µL of ethanol, retention time of 12.06 min.
N,N-Dim eth yla m in oeth yl 18-Meth oxycor on a r id in a te
(8). The lithium salt 6 (50 mg, 0.14 mmol) was suspended in
dry THF (25 mL), and dry pyridine (15 µL, 0.19 mmol) was
added. At 0 °C, oxalyl chloride (280 µL, 0.56 mmol) was added.
The mixture was stirred for 40 h at room temperature. Sodium
hydride (90 mg, 60%, 2.25 mmol) was suspended in dry THF
(10 mL), and at 0 °C N,N-dimethylethanolamine (0.46 mL, 4.58
mmol) was added. The mixture was stirred for 20 min at 0 °C
and then for 1 h at room temperature. At 0 °C, the sodium
alcoholate was dropped into the above acid chloride solution.
After being stirred for 1 h at that temperature, the reaction
mixture was quenched with buffer solution (pH 7), concen-
trated at 32 °C, and partitioned between dichloromethane and
water. The aqueous layer was extracted with dichloromethane
(3 × 20 mL), and the combined organic layers were washed
with brine to neutral, dried over sodium sulfate for 1 h, and
concentrated. Chromatography on silica gel, eluting with
dichloromethane/methanol (17:1), gave the title compound 8
(46 mg, 78%) as a white solid: mp 112-113 °C; TLC Rf ) 0.23
(silica gel, dichloromethane/methanol, 13:1, CAS blue); UV
(EtOH) λmax 228, 286 nm; IR (film) νmax 2927, 2860, 1729, 1457,
1
1366, 1281, 1257, 1232, 1174, 1122, 1037, 950, 739 cm-1; H
NMR (CDCl3) δ 1.13 (d, J ) 11 Hz, 1 H), 1.62-1.68 (m, 1 H),
1.75-1.78 (m, 3 H), 1.84-1.91 (m, 2 H), 2.40 (s, 6 H), 2.54-
2.59 (m, 1 H), 2.65-2.70 (m, 1 H), 2.78-2.81 (m, 2 H), 2.92-
2.94 (m, 1 H), 3.00-3.02 (m, 1 H), 3.24-3.29 (m, 1 H), 3.30 (s,
3 H), 3.32-3.43 (m, 5 H), 4.16-4.18 (m, 1 H), 4.59-4.60 (m, 1
H), 7.04 (t, J ) 8 Hz, 1 H), 7.09 (t, J ) 8 Hz, 1 H), 7.20 (d, J
) 8 Hz, 1 H), 7.46 (d, J ) 8 Hz, 1 H), 9.92 (s, 1 H); 13C NMR
(CDCl3) δ 21.4, 27.0, 31.1, 33.7, 34.8, 36.6, 45.4, 49.9, 53.7,
55.6, 58.0, 58.6, 59.8, 61.6, 71.0, 110.6, 110.9, 118.1, 118.8,
121.3, 129.2, 135.7, 139.4, 174.0; MS (CI), m/ z (rel intensity)
427 (M+ + 2, 32), 426 (M+ + 1, 100), 93 (5). HRMS calcd for
18-Met h oxycor on a r id in e 2-Met h oxyet h yla m id e (14).
Following the above procedure, the reaction of the 18-meth-
oxycoronaridine-derived acid chloride with 2-methoxyethyl-
amine and chromatography, twice on silica gel, first eluting
with dichloromethane/methanol (15:1) and then with hexane/
ethyl acetate (1:3), gave the title compound 14 (95%) as a white
solid: mp 155-156 °C; TLC Rf ) 0.4 (silica gel, dichlo-
romethane/methanol, 15:1, CAS blue); UV (EtOH) λmax 228,
286 nm; IR (KBr) νmax 3271, 2931, 1645, 1533, 1461, 1360,
C
25H36N3O3: 426.2757. Found: 426.2738. HPLC: (a) silica C5,
32 bar, 1 mL/min, hexane/2-propanol/triethylamine (49:1:0.5),
injection in 20 µL of 2-propanol, retention time of 14.95 min,
98.3%, 12.93 min, 1.7% impurity; (b) Cyclobond I 2000, 32 bar,
1 mL/min, hexane/ethanol (9:1), injection in 20 µL of THF,
retention time of 10.96 min.
1
1293, 1197, 1090, 1011, 748 cm-1; H NMR (CDCl3) δ 1.13-
1.15 (m, 1 H), 1.61-1.65 (m, 1 H), 1.74-1.93 (m, 5 H), 2.78-
2.84 (m, 2 H), 2.92-3.0 (m, 2 H), 3.21-3.24 (m, 2 H), 3.27 (s,
3 H), 3.32 (s, 3 H), 3.36-3.45 (m, 8 H), 6.05 (s, 1 H), 7.07 (t, J
) 8 Hz, 1 H), 7.13 (t, J ) 8 Hz, 1 H), 7.22 (d, J ) 8 Hz, 1 H),
7.47 (d, J ) 8 Hz, 1 H), 8.24 (s, 1 H); 13C NMR (CDCl3) δ 22.2,
27.2, 32.1, 33.8, 35.5, 39.8, 51.4, 53.3, 55.3, 58.5, 58.7, 59.8,
71.1, 71.8, 110.2, 110.4, 118.3, 119.1, 121.9, 128.8, 135.7, 138.3,
2-Meth oxyeth yl 18-Meth oxycor on a r id in a te (11). Fol-
lowing the above procedure, the reaction of the 18-methoxy-
coronaridine-derived acid chloride with sodium 2-methoxy-
ethanolate and chromatography on silica gel, eluting with
hexane/ethyl acetate (1:1), gave compound 11 (83%) as a
colorless oil: TLC Rf ) 0.2 (silica gel, hexane/ethyl acetate,
1:1, CAS blue); UV (EtOH) λmax 228, 286 nm; IR (film) νmax

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2723
3327, 2929, 1729, 1653, 1559, 1460, 1368, 1346, 1228, 1198,
Hz, 1 H), 8.05 (s, 1 H); 13C NMR (CDCl3) δ 22.0, 22.5, 27.3,
31.7, 33.5, 34.3, 36.5, 38.8, 51.7, 53.2, 57.7, 58.1, 64.6, 70.4,
110.3, 110.5, 118.3, 119.2, 119.3, 121.9, 128.7, 135.5, 136.4,
170.7, 175.1; MS (FAB), m/ z (rel intensity) 440 (M+ + 1, 100),
355 (25), 154 (36), 93 (45). HRMS calcd for C25H34N3O4:
440.2549. Found: 440.2544. HPLC: (a) silica C5, 35 bar, 1
mL/min, hexane/2-propanol/triethylamine (9:1:0.1), injection
in 20 µL of 2-propanol, retention time of 18.34 min; (b)
Cyclobond I 2000, 32 bar, 1 mL/min, hexane/ethanol (9:1),
injection in 20 µL EtOH, retention time 14.80 min.
1
1122, 1029, 866, 743 cm-1; H NMR (CDCl3) δ 1.15-1.17 (m,
1 H), 1.68-1.78 (m, 4 H), 1.86-1.90 (m, 3 H), 2.66 (d, J ) 13
Hz, 1 H), 2.88-2.94 (m, 3 H), 3.23-3.28 (m, 2 H), 3.32 (s, 3
H), 3.33-3.35 (m, 1 H), 3.41 (s, 3 H), 3.42-3.44 (m, 1 H), 3.47
(s, H), 3.58-3.62 (m, 2 H), 4.27-4.29 (m, 1 H), 4.46-4.48 (m,
1 H), 7.06 (t, J ) 7 Hz, 1 H), 7.12 (t, J ) 7 Hz, 1 H), 7.21 (d,
J ) 8 Hz, 1 H), 7.46 (d, J ) 8 Hz, 1 H), 8.37 (s, 1 H); 13C NMR
(CDCl3) δ 21.8, 27.2, 31.6, 33.9, 34.4, 36.6, 50.7, 53.3, 55.3,
58.5, 58.8, 63.2, 70.3, 70.9, 110.4, 110.5, 118.3, 119.1, 121.7,
128.9, 135.5, 137.6, 174.3; MS (FAB), m/ z (rel intensity) 413
(M+ + 1, 10), 289 (4), 246 (12), 185 (36), 154 (74), 137 (64),
120 (12), 107 (24), 93 (100). HRMS calcd for C24H33N2O4:
413.2440. Found: 413.2449. HPLC: (a) silica C5, 32 bar, 1
mL/min, hexane/2-propanol/triethylamine (49:1:0.5), injection
in 20 µL of 2-propanol, retention time of 9.06 min; (b)
Cyclobond I 2000, 30 bar, 1 mL/min, hexane/ethanol (95:5)
injection in 20 µL of EtOH, retention time of 6.27 min.
18-Meth oxycor on a r id in e 6-[(ter t-Bu tyl)ca r ba m yl]h ex-
a n a m id e (15). The lithium salt 6 (50 mg, 0.14 mmol) was
suspended in dry THF (20 mL) and dry pyridine (15 µL, 0.19
mmol). At 0 °C, oxalyl chloride (280 µL, 0.56 mmol) was added,
and the mixture was stirred for 40 h at room temperature.
tert-Butyl N-(6-aminohexyl)carbamate hydrochloride (584 mg,
2.24 mmol) was suspended in dry THF (15 mL), triethylamine
(0.63 mL, 4.5 mmol) was added, and then the mixture was
dropped slowly into the above acid chloride solution at 0 °C.
After being stirred for 2 h at 0 °C to room temperature, the
mixture was concentrated at 32 °C and the residue was
partitioned between dichloromethane and water. The aqueous
layer was extracted with dichloromethane (3 × 20 mL), and
the combined organic layers were washed with brine to
neutral, dried over sodium sulfate, and concentrated. The
crude material was directly used in the next reaction or
chromatographed on silica gel, eluting with hexane/ethyl
acetate (1:2) to give the title product 15 (38 mg, 50%) as a
white solid: mp 117-119 °C; TLC Rf ) 0.28 (silica gel, hexane/
ethyl acetate, 1:2, CAS blue); UV (EtOH) λmax 228, 286 nm;
IR (film) νmax 3303, 2930, 2857, 1691, 1648, 1521, 1462, 1391,
2-Hyd r oxyeth yl 18-Meth oxycor on a r id in a te (9). The
acid chloride prepared from the lithium salt 6 (50 mg, 0.14
mmol), in dry THF (25 mL), dry pyridine (15 µL, 0.19 mmol),
and oxalyl chloride (280 µL, 0.56 mmol), was added slowly at
0 °C to sodium ethylene glycolate [prepared from ethylene
glycol (1.25 mL, 22.4 mmol) in dry THF (10 mL), at 0 °C, and
sodium hydride (90 mg, 2.3 mmol), added slowly and stirred
for 20 min at 0 °C and then 1 h at room temperature]. The
mixture was stirred for 1 h at 0 °C, quenched with buffer
solution (pH 7, 0.1 mL), concentrated at 32 °C, and partitioned
between dichloromethane and water. The aqueous phase was
extracted with dichloromethane (3 × 20 mL), and the combined
organic layers were washed with brine to neutral, dried over
sodium sulfate, concentrated, and chromatographed twice on
silica gel, first eluting with dichloromethane/methanol (17:1),
then with hexane/ethyl acetate (1:3), to give the title product
9 (55.3 mg, 100%) as a white solid: mp 143-144 °C; TLC Rf
) 0.21 (silica gel, dichloromethane/methanol, 17:1, CAS blue);
UV (EtOH) λmax 228, 286 nm; IR (film) νmax 3379, 2928, 1724,
1
1366, 1252, 1172, 1117, 1010, 741 cm-1; H NMR (CDCl3) δ
1.12-1.26 (m, 5 H), 1.30-1.34 (m, 2 H), 1.42 (s, 9 H), 1.59-
1.64 (m, 2 H), 1.80-1.95 (m, 6 H), 2.73-2.80 (m, 2 H), 2.90-
2.93 (m, 1 H), 2.98-3.03 (m, 3 H), 3.17-3.26 (m, 4 H), 3.27-
3.28 (m, 1 H), 3.32 (s, 3 H), 3.38-3.42 (m, 1 H), 3.46-3.48 (m,
2 H), 4.46 (br s, 1 H), 5.99 (br s, 1 H), 7.07 (t, J ) 8 Hz, 1 H),
7.13 (t, J ) 7 Hz, 1 H), 7.23 (d, J ) 9 Hz, 1 H), 7.48 (d, J ) 8
Hz, 1 H), 8.23 (br s, 1 H); 13C NMR (CDCl3) δ 22.8, 26.6, 26.7,
27.8, 28.9, 29.8, 30.4, 32.9, 34.0, 34.5, 36.0, 40.4, 52.6, 53.7,
55.5, 58.9, 59.4, 72.6, 79.5, 110.2, 110.9, 118.8, 119.6, 122.4,
129.1, 136.1, 138.7, 156.5, 175.1; MS (CI), m/ z (rel intensity)
554 (M+ + 2, 36), 553 (M+ + 1, 100), 507 (10), 497 (14), 382
(10), 310 (9), 257 (6), 199 (6), 189 (9), 187 (23), 143 (23), 93
(24), 91 (47), 85 (50), 81 (53). HRMS calcd for C32H49N4O4:
553.3754. Found: 553.3752.
1
1461, 1368, 1227, 1174, 1086, 742 cm-1; H NMR (CDCl3) δ
1.12-1.14 (m, 1 H), 1.68-1.76 (m, 1 H), 1.78-1.82 (m, 2 H),
1.88-1.92 (m, 3 H), 2.61-2.65 (m, 1 H), 2.86 (d, J ) 8 Hz, 1
H), 2.92-3.00 (m, 2 H), 3.19-3.26 (m, 2 H), 3.33 (s, 3 H), 3.34-
3.45 (m, 2 H), 3.50 (br s, 1 H), 3.56-3.61 (m, 2 H), 3.74-3.76
(m, 2 H), 3.96-3.98 (m, 1 H), 4.58-4.60 (m, 1 H), 7.07 (t, J )
7 Hz, 1 H), 7.13 (t, J ) 7 Hz, 1 H), 7.23 (d, J ) 9 Hz, 1 H),
7.46 (d, J ) 8 Hz, 1 H), 7.99 (s, 1 H); 13C NMR (CDCl3) δ 22.1,
27.3, 32.0, 33.4, 34.1, 36.9, 51.2, 53.3, 55.1, 57.9, 58.1, 60.8,
67.2, 70.6, 110.3, 110.4, 118.4, 119.3, 122.0, 129.0, 135.5, 136.8,
175.5; MS (CI), m/ z (rel intensity) 400 (M+ + 2, 46), 399 (M+
+ 1, 100), 367 (12), 353 (20), 93 (65). Anal. (C23H30N2O4) C, H,
N.
18-Met h oxycor on a r id in e 6-Am in oh exa n a m id e (16).
Crude carbamate 15 (153 mg, 0.278 mmol) was dissolved in 3
N HCl/EtOAc (10 mL) at 0 °C. The reaction mixture was
stirred for 1.5 h at room temperature and concentrated at 32
°C. Saturated sodium bicarbonate solution was added at 0 °C
until pH 8-9 was obtained. The mixture was extracted with
dichloromethane (3 × 40 mL), and the combined organic layers
were washed with brine to neutral and concentrated to give
the crude amine 16, which was directly used in the next
reaction.
Biotin oyla m id es 17a ,b. To a solution of crude amine 16
(0.278 mmol) in pyridine (5 mL), (+)-biotin 4-nitrophenyl ester
(100 mg, 0.274 mmol) was added at 0 °C. The reaction mixture
was stirred overnight at room temperature, concentrated at
40 °C, then partitioned between dichloromethane and water.
The aqueous layer was extracted with dichloromethane (3 ×
40 mL), and the combined organic layers were washed with
brine to neutral, dried over sodium sulfate, concentrated, and
chromatographed twice on silica gel, first eluting with dichlo-
romethane/methanol (7.3:1), then with ethyl acetate/methanol
(4:1), to give the biotinylated products 17a ,b (135 mg, 72%,
from lithium salt 6, three steps) as a yellow powder.
2-Acetyla m in oeth yl 18-Meth oxycor on a r id in a te (10). A
sodium alcoholate solution was prepared by addition of N-
acetylethanolamine (0.42 mL, 4.6 mmol) to a suspension of
sodium hydride (90 mg, 2.3 mmol) in 4 mL of dry DMF at 0
°C. After 1 h at room temperature, this solution was added at
0 °C to the acid chloride in THF, prepared from 50 mg (0.14
mmol) of the lithium salt 6. After 1 h at 0 °C, the reaction
mixture was quenched with buffer solution (pH 7, 0.1 mL),
the THF was evaporated under reduced pressure at 32 °C, and
then DMF was evaporated under vacuum at 39 °C. The residue
was partitioned between dichloromethane and water and
worked up as above. Two chromatographies, first eluting with
dichloromethane/methanol (12.5:1), then ethyl acetate/metha-
nol (25:1), gave the title product 10 (43 mg, 71%) as a colorless
oil. TLC Rf ) 0.3 (silica gel, dichloromethane/methanol, 12.5:
1, CAS blue); UV (EtOH) λmax 226, 286 nm; IR (film) νmax 3300,
2929, 2859, 1726, 1661, 1548, 1461, 1371, 1223, 1174, 1118,
1
1036, 741 cm-1; H NMR (CDCl3) δ 1.50 (d, J ) 7 Hz, 1 H),
1.76-1.79 (m, 3 H), 1.82 (s, 3 H), 1.84-1.93 (m, 3 H), 2.61 (m,
1H), 2.82 (d, J ) 8 Hz, 1 H), 2.96-2.98 (m, 1 H), 2.99-3.03
(m, 1 H), 3.17-3.20 (m, 2 H), 3.34 (s, 3 H), 3.38-3.40 (m, 2
H), 3.44-3.48 (m, 2 H), 3.55-3.57 (m, 2 H), 3.98-4.05 (m, 1
H), 4.42-4.45 (m, 1 H), 6.67 (s, 1 H), 7.07 (t, J ) 8 Hz, 1 H),
7.13 (t, J ) 7 Hz, 1 H), 7.25 (d, J ) 8 Hz, 1 H), 7.46 (d, J ) 8
Sep a r a tion of Dia ster eom er s 17a a n d 17b. The biotin-
ylated products 17a ,b (10 mg) were loaded onto a semi-
preparative chiral ODS HPLC column and eluted with hexane/
ethanol/diethylamine (10:1:0.01) to give the two diastereoiso-
mers 17a (50%, retention time of 180 min) as a white solid
and 17b (50%, retention time of 209 min) as a white solid.

2724 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
17a : mp 119-120 °C; TLC Rf ) 0.18 (silica gel, ethyl acetate/
methanol, 4:1, CAS blue); [R]25D +50 (c 0.1, CHCl3); UV (EtOH)
λmax 228, 286 nm; IR (film) νmax 3288, 2928, 2857, 1700, 1646,
1.27 (t, J ) 7 Hz, 6 H), 2.45 (t, J ) 7 Hz, 2 H), 2.67 (d, J ) 7
Hz, 2 H), 3.37 (t, J ) 7 Hz, 2 H), 4.21 (q, J ) 7 Hz, 4 H), 5.13
(s, 1 H), 5.17 (d, J ) 7 Hz, 1 H), 5.62-5.69 (m, 1 H); 13C NMR
(CDCl3) δ 14.0, 27.0, 36.3, 37.8, 57.5, 61.6, 119.6, 131.8, 170.2;
MS (CI, isobutane, 100 eV), m/ z (rel intensity) 309 (M + 1+,
100), 307 (71), 217 (40), 192 (11).
1
1540, 1461, 1265, 1116, 736 cm-1; H NMR (CDCl3) δ 0.88-
0.92 (m, 1 H), 1.13-1.20 (m, 4 H), 1.21-1.31 (m, 3 H), 1.35-
1.44 (m, 6 H), 1.52-1.57 (m, 1 H), 1.60-1.68 (m, 4 H), 1.76-
1.89 (m, 5 H), 2.11 (t, J ) 10 Hz, 1 H), 2.64 (d, J ) 8 Hz, 1 H),
2.78-2.83 (m, 3 H), 2.92-2.94 (m, 1 H), 2.98-3.02 (m, 1 H),
2.06-2.08 (m, 1 H), 3.11-3.24 (m, 5 H), 3.31 (s, 3 H), 3.38-
3.42 (m, 1 H), 3.44-3.48 (m, 2 H), 4.28 (m, 1 H), 4.42 (m, 1
H), 5.55 (s, 1 H), 6.11 (s, 1 H), 6.28 (s, 1 H), 6.32 (s, 1 H), 7.04
(t, J ) 7 Hz, 1 H), 7.10 (t, J ) 7 Hz, 1 H), 7.28 (d, J ) 8 Hz,
1 H), 7.45 (d, J ) 8 Hz, 1 H), 9.09 (s, 1 H); 13C NMR (CDCl3)
δ 22.4, 22.7, 25.4, 26.3, 27.3, 27.9, 28.0, 29.3, 29.5, 31.6, 32.3,
33.4, 33.8, 35.2, 35.6, 39.1, 39.9, 40.5, 52.4, 55.3, 55.9, 58.5,
59.0, 60.2, 62.2, 71.7, 109.8, 110.8, 118.1, 118.9, 121.6, 128.5,
136.1, 138.8, 164.0, 173.0, 174.9; MS (CI), m/ z (rel intensity)
681 (M+ + 3, 26), 680 (M+ + 2, 54), 679 (M+ + 1, 22), 647 (22),
633 (22), 148 (100), 147 (46), 99 (20), 93 (58), 91 (40), 85 (69),
B. 6-(N-Ben zyl-N-m eth yla m in o)-4,4-d i(eth oxyca r bon -
yl)h ex-1-en e (21). To a solution of bromide 20 (20.0 g, 65.1
mmol) in dry acetone (250 mL), N-benzylmethylamine (8.40
mL, 65.1 mmol) and anhydrous K2CO3 (40 g) were added, and
the mixture was heated at reflux for 36 h with vigorous
stirring. The mixture was filtered, and the precipitate was
washed with acetone (3 × 100 mL). The filtrate was concen-
trated under reduced pressure, water (250 mL) was added,
and the layers were separated. The aqueous layer was
extracted with ether (6 × 100 mL), and the combined organic
layers were washed with 10% HCl (250 mL). The acid layer
was washed with ether (3 × 100 mL) and made basic with
10% NaOH. The basic mixture was extracted with ether (5 ×
100 mL), and the combined organic layers were washed with
brine (100 mL), dried over Na2SO4, and concentrated under
reduced pressure to yield an orange oil. The crude product was
purified by flash chromatography on silica gel, eluting with
hexanes/ethyl acetate (1:1) to yield amine 21 as a pale-yellow
oil (12.63 g, 36.4 mmol, 56%). The product can be distilled
under vacuum to yield a pale-yellow oil (bp 148-156 °C, 0.31
mmHg); TLC Rf ) 0.32 (hexanes/ether, 3:1, 1% TEA, I2); IR
(NaCl) νmax 3082, 3064, 3028, 2981, 2940, 2907, 2873, 2842,
2788, 1732, 1642, 1602, 1586, 1495, 1464, 1453, 1420, 1389,
1367, 1283, 1227, 1203, 1151, 1096, 1077, 1057, 1023, 921, 860,
738, 700 cm-1; 1H NMR (CDCl3) δ 1.23 (t, J ) 7 Hz, 6 H), 2.13
(t, J ) 7 Hz, 2 H), 2.19 (s, 3 H), 2.35 (t, J ) 7 Hz, 2 H), 2.62
(d, J ) 7 Hz, 2 H), 3.48 (s, 2 H), 4.14 (q, J ) 7 Hz, 4 H), 5.01-
5.07 (m, 2 H), 5.57-5.66 (m, 1 H), 7.24-7.31 (m, 5 H); 13C NMR
(CDCl3) δ 13.9, 39.3, 36.8, 42.0, 51.9, 56.1, 61.0, 62.5, 118.7,
126.8, 128.0, 128.9, 132.4, 138.9, 170.9; MS (CI, isobutane, 100
eV), m/ z (rel intensity) 348 (M + 1+, 24), 276 (11), 167 (5),
134 (12), 91 (5). Anal. (C20H29NO4) C, H, N.
C. 6-(N-Ben zyl-N-m eth yla m in o)-4-eth oxyca r bon yl-1-
en e (22). A solution of diester 21 (12.0 g, 34.6 mmol) and LiCl
(3.2 g, 76 mmol) in DMSO (32 mL), DMF (6.5 mL), and water
(0.5 mL) was heated at 180 °C for 6 h under nitrogen. The
resulting dark-brown reaction mixture was cooled to room
temperature and poured into water (150 mL). The mixture was
extracted with dichloromethane (5 × 100 mL), and the
combined organic phases were washed with ice/water (3 × 100
mL) and brine (100 mL). Drying over sodium sulfate and
condensation under reduced pressure gave a brown oil, which
was purified by flash chromatography on silica gel, eluting
with hexanes/ethyl acetate (1:1) to yield a yellow oil (9.26 g,
33.6 mmol, 97%), which was distilled under vacuum to yield
a colorless oil (bp 143-146 °C, 0.11 mmHg). TLC Rf ) 0.54
(ether/hexanes, 1:1); IR (NaCl) νmax 3064, 3028, 2979, 2951,
2841, 2790, 1733, 1642, 1495, 1454, 1374, 1261, 1177, 1145,
1026, 916, 860, 738, 699 cm-1; 1H NMR (CDCl3) δ 1.22 (t, J )
7 Hz, 3 H), 1.63-1.69 (m, 1 H), 1.83-1.90 (m, 1 H), 2.16 (s, 3
H), 2.19-2.25 (m, 1 H), 2.31-2.40 (m, 3 H), 2.50-2.56 (m, 1
H), 3.46 (s, 2 H), 4.05-4.15 (q, J ) 7 Hz, 2 H), 4.99-5.05 (m,
2 H), 5.69-5.77 (m, 1 H), 7.20-7.33 (m, 5 H); 13C NMR (CDCl3)
δ 14.2, 15.2, 29.1, 36.4, 41.9, 43.1, 54.9, 60.0, 62.5, 65.7, 116.7,
126.8, 128.1, 128.9, 135.4, 139.2, 175.3; MS (EI, 70 eV), m/ z
(rel intensity) 275 (M+, 14), 230 (4), 202 (4), 134 (97), 91 (100).
Anal. (C17H25NO2) C, H, N.
83 (35), 81 (50), 79 (58), 77 (24). HRMS calcd for C37H55
-
N6O4S: 679.4006. Found: 679.4012. HPLC: (a) silica C5, 57
bar, 1 mL/min, hexane/2-propanol/triethylamine (3:2:0.05),
injection in 20 µL of 2-propanol, retention time of 13.76 min;
(b) Cyclobond I 2000, 97 bar, 2 mL/min, hexane/ethanol (6:4),
injection in 20 µL of EtOH, retention time of 5.89 min (98.7%
purity), retention time of 1.62 min (1.3% impurity).
17b: mp 119-120 °C; TLC Rf ) 0.18 (silica gel, ethyl acetate/
methanol, 4:1, CAS blue); [R]25D +10 (c 0.1, CHCl3); UV (EtOH)
λmax 206, 228, 286 nm; IR (film) νmax 3289, 2927, 1670, 1653,
1540, 1458, 1265 cm-1 1H NMR (CDCl3) δ 0.88-0.92 (m, 1
;
H), 1.14-1.28 (m, 8 H), 1.36-1.43 (m, 6 H), 1.66-1.69 (m, 4
H), 1.74-1.78 (m, 1 H), 1.82-1.88 (m, 4 H), 2.15-2.18 (m, 1
H), 2.64 (d, J ) 10 Hz, 1 H), 2.76-2.85 (m, 2 H), 2.92-2.94
(m, 1 H), 3.03-3.20 (m, 7 H), 3.23-3.27 (m, 1 H), 3.31 (s, 3
H), 3.41-3.47 (m, 3 H), 4.26 (m, 1 H), 4.37 (m, 1 H), 5.37 (s, 1
H), 6.11 (s, 2 H), 6.32 (s, 1 H), 7.05 (t, J ) 7 Hz, 1 H), 7.11 (t,
J ) 7 Hz, 1 H), 7.28 (d, J ) 8 Hz, 1 H), 7.45 (d, J ) 7 Hz, 1 H),
9.07 (s, 1 H); 13C NMR (CDCl3) δ 22.3, 22.7, 25.8, 26.0, 27.4,
28.1, 29.2, 29.3, 31.6, 32.2, 33.4, 33.8, 35.0, 36.1, 38.9, 39.7,
40.6, 52.8, 53.2, 55.2, 55.5, 58.4, 58.8, 60.1, 61.8, 71.7, 109.7,
110.8, 118.1, 118.9, 121.7, 128.4, 136.0, 138.6, 163.9, 173.1,
174.8; MS (CI), m/ z (rel intensity) 682 (31), 681 (80), 680 (M+
+ 2, 100), 679 (29), 678 (M+, 15), 633 (22), 171 (10), 148 (44),
147 (31), 93 (89), 91 (65), 85 (77), 83 (61), 81 (78), 79 (65), 77
(42). HRMS calcd for C37H55N6O4S: 679.4006. Found: 679.3981.
HPLC: (a) silica C5, 56 bar, 1 mL/min, hexane/2-propanol/
triethylamine (3:2:0.05), injection in 20 µL of 2-propanol,
retention time of 14.12 min; (b) Cyclobond I 2000, 97 bar, 2
mL/min, hexane/ethanol (60:40), injection in 20 µL of ethanol,
retention time of 5.93 min (98.3% purity), retention time of
1.72 min (1.7% impurity).
Tota l Syn th esis of 18-Meth yla m in ocor on a r id in e a n d
18-Dim eth yla m in ocor on a r id in e (18 a n d 19). A. 6-Br om o-
4,4-d i(eth oxyca r bon yl)h ex-1-en e (20). A solution of diethyl
allylmalonate (75.0 g, 0.370 mol) in dry THF (100 mL) was
added dropwise at room temperature to a stirred suspension
of sodium hydride (60% dispersion in mineral oil, 18.2 g, 0.456
mol) in dry THF (100 mL) over a period of 30 min. The mixture
was stirred for 1 h at room temperature, and a solution of 1,2-
dibromoethane (64.0 mL, 0.740 mol) in dry THF (100 mL) was
added dropwise over 30 min. The mixture was stirred for 15
h at room temperature and then poured into water (750 mL).
The mixture was concentrated under reduced pressure, and
the concentrate was extracted with ether (5 × 200 mL). The
combined ether extracts were washed with brine (250 mL),
dried over anhydrous sodium sulfate, and concentrated under
reduced pressure to yield a yellow oil. Excess 1,2-dibromo-
ethane and unreacted diethylallyl malonate were removed by
Kugelrohr distillation to yield the bromoester as a viscous
yellow oil (91.50 g, 0.2979 mol, 81%). Fractional distillation
under high vacuum yielded a colorless oil (bp 114-116 °C, 0.19
mmHg). IR (NaCl) νmax 3081, 2983, 2938, 2908, 1732, 1643,
1466, 1446, 1391,1369, 1336, 1299, 1273, 1244, 1204, 1175,
1161, 1097, 1032, 924, 859, 749, 641 cm-1; 1H NMR (CDCl3) δ
D. 2-(2-N-Ben zyl-N-m eth yla m in oeth yl)p en t-4-en ol (23).
To a solution of the ester 22 (6.80 g, 24.7 mmol) in dry ether
(75 mL) was added dropwise a 1 M solution of lithium
aluminum hydride in ether (12.3 mL, 12.3 mmol) at 0 °C over
5 min. The mixture was stirred for 1.5 h at room temperature
and then cooled to 0 °C and quenched with water (1 mL),
followed by 15% NaOH (1 mL) and water (3 mL). The white
precipitate was filtered and washed with ether (4 × 25 mL).
The filtrate was dried over sodium sulfate and concentrated
under reduced pressure to yield a pale-yellow viscous oil, which
was distilled (bp 134-136 °C, 0.090 mmHg) to yield alcohol

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2725
23 (5.62 g, 24.1 mmol, 98%). TLC Rf ) 0.46 (2% TEA in ethyl
acetate); IR (NaCl) νmax 3392, 3073, 3065, 3029, 2974, 2919,
2840, 2800, 1640, 1495, 1454, 1366, 1073, 1045, 996, 912, 738,
the mixture was stirred for 3 h at 0 °C. Aqueous sodium
hydroxide (15%, 11 mL) and aqueous hydrogen peroxide (30%,
11 mL) were added dropwise at 0 °C, and the mixture was
heated at reflux for 1 h. The reaction mixture was then cooled
to room temperature, and the layers were separated. The
aqueous layer was extracted with dichloromethane (5 × 50
mL). The combined organic layers were washed with brine (2
× 50 mL), dried over sodium sulfate, and concentrated to a
pale-yellow oil. This was dissolved in benzene (20 mL), and
triphenylphosphine (3.83 g, 14.6 mmol, 1.0 equiv) was added.
The mixture was heated at reflux for 3 h to reduce any N-oxide
present. Benzene was removed under reduced pressure to yield
a yellow, viscous residue, which was purified by flash chro-
matography on silica gel, eluting with ether/methanol/TEA (98:
2:1) to yield a viscous yellow oil (4.055 g, 13.8 mmol, 95%);
TLC Rf ) 0.16 (5% methanol in ether, PMA); IR (NaCl, neat)
νmax 3409, 3062, 3085, 3062, 3028, 2941, 2875, 2789, 1495,
1453, 1403, 1367, 1212, 1124, 1058, 1028, 947, 914, 740, 700
cm-1; 1H NMR (CDCl3) δ 1.32-1.39 (m, 1 H), 1.44-1.64 (m, 2
H), 1.72-1.80 (m, 2 H), 1.89 (br s, 1 H), 2.18 (s, 3 H), 2.37-
2.43 (m, 1 H), 2.45-2.55 (m, 1 H), 3.44-3.52 (m, 2 H), 3.59-
3.61 (t, J ) 6 Hz, 2 H), 3.80-3.85 (m, 2 H), 3.88-3.95 (m, 2
H), 4.76-4.77 (d, J ) 4 Hz, 1 H), 7.21-7.32 (m, 6 H, signal +
solvent); 13C NMR (CDCl3) δ 25.2, 26.5, 30.1, 38.8, 42.0, 54.9,
62.1, 62.7, 64.8, 106.6, 126.9, 128.1; MS (CI, isobutane, 100
eV) m/ z (rel intensity) 294 (M + 1+, 100), 221 (6), 204 (6), 171
(1), 142 (4), 134 (25), 91 (12). Anal. (C17H27NO3) C, H, N.
1
699 cm-1; H NMR (CDCl3) δ 1.52-1.57 (m, 1 H), 1.65-1.75
(m, 2 H), 1.92-1.97 (m, 1 H), 2.03-2.09 (m, 1 H), 2.15 (s, 3
H), 2.47 (t, J ) 6 Hz, 2 H), 3.36-3.40 (m, 1 H), 3.47-3.60 (m,
3 H), 4.97-5.00 (m, 2 H), 5.71-5.79 (m, 1 H), 6.59 (s, 1 H),
7.24-7.32 (m, 5 H); 13C NMR (CDCl3) δ 31.0, 36.7, 41.1, 41.2,
55.9, 62.5, 66.4, 116.0, 127.3, 128.3, 129.3, 136.8, 137.2; MS
(CI, isobutane, 100 eV), m/ z (rel intensity), 234 (M + 1+, 100),
134 (34), 91 (30) Anal. (C15H23NO) C, H, N.
E. 2-(2-N-Ben zyl-N-m eth yla m in oeth yl)p en t-4-en a l (24).
A solution of dry DMSO (4.3 mL, 60 mmol) in dry CH2Cl2 (20
mL) was added dropwise to a stirred 2 M solution of oxalyl
chloride in CH2Cl2 (15 mL, 30 mmol) at -78 °C over 10 min.
After the mixture was stirred for 30 min at -78 °C, dry DMF
(three drops) was added. The mixture was stirred for another
10 min, and a solution of alcohol 23 (5.56 g, 23.8 mmol) in dry
CH2Cl2 (50 mL) was added dropwise over 20 min. Then the
mixture was stirred an additional 45 min at -78 °C, and a
solution of dry triethylamine (9.95 mL, 71.4 mmol) in dry CH2-
Cl2 (25 mL) was added dropwise over 10 min. The mixture
was stirred overnight, warming gradually from -78 °C to room
temperature over 10 h. The reaction mixture was quenched
by adding water (25 mL) dropwise, with stirring, over 5 min.
The mixture was poured into CH2Cl2 (200 mL), and the layers
were separated. The aqueous phase was extracted with CH2-
Cl2 (3 × 100 mL), and the combined organic phases were
washed with ice/water (3 × 100 mL) and brine (200 mL).
Drying over sodium sulfate and condensation under reduced
pressure gave a yellow oil (5.08 g, 22.0 mmol, 92%), which was
used in the next step without further purification. TLC Rf )
0.53 (hexanes/ethyl acetate/TEA, 2:1:0.1); IR (NaCl, neat) νmax
3064, 3028, 2977, 2929, 2841, 2795, 2718, 1724, 1641, 1602,
1495, 1453, 1419, 1366, 1354, 1301,1257, 1209, 1153, 1126,
1076, 1027, 995, 916, 738, 700 cm-1; 1H NMR (CDCl3) δ 1.65-
1.72 (m, 1 H), 1.83-1.91 (m, 1 H), 2.15 (s, 3 H), 2.16-2.19 (m,
1 H), 2.30-2.44 (m, 4 H), 3.47 (s, 2 H), 4.99-5.05 (m, 2 H),
5.67-5.73 (m, 1 H), 9.63 (d, J ) 2 Hz, 1 H); 13C NMR (CDCl3)
δ 26.7, 32.8, 41.6, 49.1, 54.1, 62.4, 116.9, 126.8, 128.0, 128.8,
134.9, 138.7, 203.4; MS (CI, isobutane, 100 eV), m/ z (rel
intensity) 232 (M + 1+, 100), 203 (8), 134 (34), 91 (17).
H. 4-(1,3-Dioxola n -2-yl)-6-(N-m eth yla m in o)h exa n -1-ol
(27). N-Benzylamine 26 (3.343 g, 11.39 mmol) was dissolved
in glacial acetic acid (100 mL), and 10% palladium on activated
carbon (dry, 1.4 g) catalyst was added. The mixture was
degassed under high vacuum and purged with nitrogen and
then with hydrogen. The reaction mixture was stirred for 12
h under 1 atm of hydrogen. It was then purged with nitrogen
and filtered, and the filtrate was concentrated under reduced
pressure to ca. 5 mL. At 0 °C, saturated NH4OH was added
dropwise until the mixture was basic. The mixture was
extracted with dichloromethane (5 × 25 mL), and the combined
organic layers were dried over sodium sulfate, filtered, and
concentrated under reduced pressure to a pale-yellow, viscous
oil (2.285 g, 11.24 mmol, 99%). The crude product was
subjected to the following protection step without further
purification. TLC Rf ) 0.25 (10% methanol in dichloromethane,
PMA); IR (NaCl, neat) νmax 3371, 2945, 2880, 2782, 2448, 1710,
1665, 1597, 1471, 1404, 1273, 1228, 1211, 1132, 1102, 1056,
F . 4-(1,3-Dioxola n -2-yl)-6-(N-ben zyl-N-m eth yla m in o)-
1-h exen e (25). Crude aldehyde 24 (13.1 g, 21.2 mmol) was
added to a stirred solution of dry ethylene glycol (6.97 mL,
125 mmol) in dry CH2Cl2 (300 mL). Chlorotrimethylsilane (31.7
mL, 250 mmol) was added dropwise over 5 min. The mixture
was heated at reflux under nitrogen for 72 h and concentrated
under reduced pressure. The oily residue was subjected to flash
chromatography on silica gel, eluting with hexanes/ethyl
acetate (2:1) to yield the product as a yellow oil (14.02 g, 50.9
mmol, 90%). Distillation under vacuum gave a colorless oil (bp
140-142°C, 0.12 mmHg). TLC Rf ) 0.62 (hexanes/ethyl
acetate, 1:1, I2); IR (NaCl, neat) νmax 3064, 3027, 2976, 2946,
2881, 2840, 2786, 1949, 1825, 1640, 1495, 1453, 1417, 1400,
1366, 1313, 1254, 1212, 1123, 1074, 1027, 997, 946, 913, 827,
1
946, 775, 734, 700 cm-1; H NMR (CDCl3) δ 1.39-1.80 (m, 9
H), 2.17 (br s, 3 H), 2.42 (s, 3 H), 2.64-2.71 (m, 2 H), 3.62-
3.67 (m, 2 H), 3.83-3.88 (m, 2 H), 3.91-3.96 (m, 2 H), 4.77-
4.78 (d, J ) 4 Hz, 1 H); 13C NMR (CDCl3) δ 25.5, 28.2, 30.0,
35.4, 38.9, 49.4, 62.1, 64.7, 64.8, 106.5; MS (CI, isobutane, 100
eV) m/ z (rel intensity) 204 (M + 1+, 100), 184 (10), 170 (3),
158 (10), 142 (23), 131 (5), 114 (2), 101 (7).
I. 4-(1,3-Dioxola n -2-yl)-6-[N-(ter t-BOC)-N-m eth yla m i-
n o]h exa n -1-ol (28). The crude amino alcohol 27 (1.202 g, 5.91
mmol) was dissolved in dry dichloromethane (50 mL) and
cooled to 0 °C. Di-tert-butyl dicarbonate (1.63 mL, 7.09 mmol,
1.2 equiv) was added dropwise (gas evolution) via syringe over
a period of 5 min. After the addition was complete, the ice bath
was removed and the mixture was stirred for 13 h at room
temperature. The mixture was concentrated under reduced
pressure, and the residue was subjected to flash chromatog-
raphy on silica gel, eluting with 5% methanol in dichlo-
romethane to yield a highly viscous, deep-yellow oil (1.780 g,
5.866 mmol, 99%). TLC Rf ) 0.5 (5% methanol in dichlo-
romethane, PMA); IR (NaCl, neat) νmax 3447, 2974, 2935, 2880,
2246, 1691, 1540, 1482, 1456, 1400, 1366, 1312, 1250, 1222,
1159, 1094, 1056, 945, 922, 880, 773, 733, 646 cm-1; 1H NMR
(CDCl3) δ 1.45-1.74 (m, 18 H), 2.83 (s, 3 H), 3.24 (br s, 1.5 H),
3.46 (br s, 0.5 H), 3.83-3.88 (m, 2 H), 3.92-3.98 (m, 2 H),
4.78-4.79 (d, J ) 4 Hz, 1 H); 13C NMR (CDCl3) δ 24.92, 25.4,
26.6, 27.2, 28.3, 31.0, 33.8, 38.0, 38.9, 46.1, 47.3, 62.1, 62.6,
64.8, 79.1, 106.3, 155.7; MS (CI, isobutane, 100 eV) m/ z (rel
intensity) 304 (M + 1+, 13), 260 (6), 242 (100), 204 (4), 198
(8), 186 (37), 158 (3), 142 (92). Anal. (C15H29NO5) C, H, N.
781, 738, 699 cm-1 1H NMR (CDCl3) δ 1.49-1.56 (m, 1 H),
;
1.67-1.74 (m, 1 H), 1.81-1.86 (m, 1 H), 2.05-2.12 (quint, J
) 7 Hz, 1 H), 2.18 (s, 3 H), 2.20-2.26 (m, 1 H), 2.39-2.46 (m,
2 H), 3.47-3.48 (d, J ) 4 Hz, 2 H), 3.80-3.86 (m, 2 H), 3.88-
3.94 (m, 2 H), 4.80-4.81 (d, J ) 4 Hz, 1 H), 4.96-5.03 (m, 2
H), 5.75-5.83 (m, 1 H), 7.21-7.31 (m, 5 H); 13C NMR (CDCl3)
δ 26.1, 33.7, 39.3, 42.1, 55.1, 62.3, 64.9, 65.0, 106.2, 116.0,
126.8, 128.1, 129.0, 136.9, 139.4; MS (EI, 70 eV) m/ z (rel
intensity) 275 (M+, 3), 202 (5), 160 (3), 134 (85), 120 (13), 91
(100). Anal. (C17H25NO2) C, H, N.
G. 4-(1,3-Dioxola n -2-yl)-6-(N-ben zyl-N-m eth yla m in o)-
h exa n -1-ol (26). Disiamylborane reagent was prepared in situ
by adding a 2 M solution of 2-methyl-2-butene in THF
dropwise to a stirred 1 M solution of borane‚THF in THF at
-10 °C over a period of 30 min. The mixture was stirred for 3
h at -10 °C to complete the reaction. A solution of olefin 25
(4.03 g, 14.6 mmol) in dry THF (20 mL) was then added, and

2726 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
J . 4-(1,3-Dioxola n -2-yl)-6-[N-(tBOC)-N-m eth yla m in o]-
h exa n -1-a l (29). The alcohol 28 (1.770 g, 5.838 mmol) was
oxidized using 2 M (COCl)2 (3.79 mL, 7.58 mmol), dry DMSO
(1.08 mL, 15.2 mmol), dry DMF (1 drop), and dry triethylamine
(2.43 mL, 17.4 mmol), analogous to the oxidation of alcohol
23. Similar workup as for aldehyde 24 yielded aldehyde 29
(1.626 g, 5.395 mmol, 92%) as a yellow oil. TLC Rf ) 0.63 (ethyl
acetate/hexanes, 2:1; DNP yellow); IR (NaCl, neat) νmax 2976,
2933, 2887, 2722, 1809, 1725, 1693, 1481, 1456, 1424, 1396,
1366, 1309, 1248, 1215, 1158, 1072, 947, 881, 846, 773, 736,
4.75 (m, 0.2 H), 5.08-5.09 (d, J ) 8 Hz, 0.1 H), 5.59-5.62 (m,
1 H), 7.00-7.15 (m, 3 H), 7.24-7.43 (m, 11 H, signal + solvent),
8.58-8.90 (m, 1 H); 13C NMR (CDCl3) δ 14.0, 20.9, 24.9, 25.5,
26.0, 27.3, 27.7, 28.3, 30.8, 33.2, 36.0, 36.2, 40.2, 41.6, 45.9,
46.2, 46.6, 46.8, 51.9, 52.3, 56.1, 60.2, 70.0, 62.1, 63.1, 64.3,
64.4, 64.4, 64.7, 78.8, 105.4, 106.2, 110.4, 110.5, 111.4, 114.2,
117.5, 117.9, 118.7, 121.1, 126.8, 127.8, 128.1, 128.5, 129.3,
131.5, 133.8, 135.6, 135.8, 139.6, 155.4, 175.0, 175.6; MS (CI,
isobutane, 100 eV) m/z (rel intensity) 620 (M + 1+, 72), 530
(2), 334 (5), 133 (6), 107 (72), 91 (100). HRMS (FAB) calcd for
702 cm-1
;
1H NMR (CDCl3) δ 1.41-1.53 (m, 14 H, signal +
C
36H50N3O6 (M+): 620.3699. Found: 620.3678.
solvent), 1.63-1.76 (m, 4 H), 1.79-1.87 (sextet, J ) 8 Hz, 1
H), 2.54-2.57 (t, J ) 8 Hz, 2 H), 2.83 (s, 3 H), 3.27 (br m, 2
H), 3.82-3.87 (m, 2 H), 3.93-3.96 (m, 2 H), 4.75-4.76 (d, J )
4 Hz, 1 H), 9.76 (m, 1 H); 13C NMR (CDCl3) δ 21.3, 26.9, 26.2,
28.2, 33.8, 38.3, 38.7, 40.8, 41.5, 46.3, 46.8, 64.6, 64.6, 79.0,
106.0, 155.4, 201.9; GC-MS (CI, methane, 100 eV), m/ z (rel
intensity) 342 (M + C3H5 ), 302 (M + 1+, 0.4), 286 (3), 274 (5),
246 (6), 202 (19), 184 (6), 168 (3), 140 (100).
M. N-H Clea va m in es (33). Cleavamines 32 (1.399 g, 2.257
mmol) were dissolved in glacial acetic acid (30 mL), and 10%
palladium on activated carbon (dry, 0.28 g) was added. The
reaction flask was degassed under high vacuum and purged
with nitrogen and then with hydrogen. The mixture was
stirred for 4 h at room temperature under hydrogen (1 atm).
After being purged with nitrogen, the mixture was filtered
through Celite and the filter cake was washed with methanol.
1
K. Tetr a cycles (31). A mixture of N-benzylindoloazepine
30 (0.100 g, 0.300 mmol) and aldehyde 29 (0,132 g, 0.438 mmol,
1.5 equiv) was stirred (neat) in an open flask at 135 °C for 30
min, when TLC indicated that the condensation was complete.
The gummy residue was dissolved in methanol/dichloromethane
(1:5, 6 mL), and sodium borohydride (powder, 0.010 g) was
added to reduce the excess aldehyde. The mixture was stirred
for 15 min, and water (1 mL) was added. The layers were
separated, and the aqueous layer was washed with dichlo-
romethane (4 × 5 mL). The combined organic layers were
washed with brine (5 mL), dried over sodium sulfate, and
concentrated under reduced pressure to yield a yellow foam,
which was purified by centrifugal chromatography, eluting
with hexanes/ether (4:1) to yield product 31, an inseparable
mixture of diastereomers, as a white foam (0.173 g, 0.280
mmol, 93%). TLC Rf ) 0.57 (hexanes/ethyl acetate, 1:1, CAS
blue-yellow); UV (EtOH) λmax 204, 300, 330 nm; IR (NaCl, thin
film) νmax 3377, 3059, 3026, 2973, 2934, 2889, 2795, 2248, 1689,
1681, 1611, 1479, 1466, 1454, 1437, 1392, 1366, 1345, 1303,
1280, 1249, 1205, 1155, 1126, 1104, 1050, 946, 912, 880, 772,
The filtrate was concentrated to ca. /8 volume under reduced
pressure, poured onto crushed ice, made basic with NH4OH,
and extracted with dichloromethane (5 × 20 mL). The com-
bined organic layers were washed with brine (25 mL), dried
over sodium sulfate, filtered, and concentrated to yield a yellow
oil, which was purified by centrifugal chromatography on silica
gel, eluting with ethyl acetate to yield the amines 33 as a white
foam (1.121 g, 2.116 mmol, 94%). TLC Rf ) 0.47 (10% methanol
in dichloromethane, CAS yellow); UV (EtOH) λmax 210, 228.
286 nm; IR (NaCl, thin film), νmax 3366, 3055, 2974, 2927, 1730,
1691, 1608, 1485, 1462, 1398, 1366, 1339, 1307, 1247, 1160,
1052, 1032, 1012, 947, 880, 771, 740, 703 cm-1 1H NMR
;
(CDCl3) δ 0.80-1.08 (m, 2 H), 1.08-1.22 (m, 2 H), 1.22-1.32
(m, 2 H), 1.32-1.65 (m, 19 H), 1.70-1.77 (m, 2 H), 2.00-2.10
(m, 2 H), 2.20-2.25 (t, J ) 13 Hz, 2 H), 2.34-2.43 (m, 2 H),
2.44-2.52 (m, 3 H), 2.62-2.73 (m, 3 H), 2.76-3.01 (m, 4 H),
3.10-3.18 (m, 2 H), 3.21-3.32 (m, 1 H), 3.34-3.62 (m, 4 H),
3.70-3.77 (s, 3 H), 3.82-3.87 (m, 1 H), 3.90-3.96 (m, 1 H),
4.04-4.06 (t, J ) 7 Hz, 0.3 H), 4.34-4.35 (d, J ) 4 Hz, 0.5 H),
4.52-4.53 (d, J ) 4 Hz, 0.5 H), 5.44-5.54 (m, 1 H), 7.02-7.05
(t, J ) 7 Hz, 1 H), 7.08-7.11 (t, J ) 7 Hz, 1 H), 7.28-7.30 (d,
J ) 7 Hz, 1 H), 7.45-7.47 (d, J ) 7 Hz, 1 H), 8.60-8.94 (m,
0.5 H); 13C NMR (CDCl3) δ 27.1, 27.2, 28.3, 29.6, 31.3, 33.4,
33.9, 33.4, 33.9, 36.0, 36.4, 38.8, 39.3, 39.7, 41.7, 43.3, 45.9,
46.3, 46.9, 49.5, 50.0, 51.2, 51.9, 57.0, 64.4, 64.5, 64.6, 64.8,
105.4, 106.0, 106.2, 110.5, 110.6, 114.0, 117.7, 118.7, 121.2,
126.8, 127.7, 131.8, 135.6; MS (CI, isobutane, 100 eV) m/z (rel
intensity) 530 (M + 1+, 91), 498 (3), 472 (2), 290 (3), 239 (1),
184 (26), 162 (59), 93 (100). HRMS (FAB) calcd for C29H44N3O6
(M+): 530.3230. Found: 530.3238.
745, 735, 700 cm-1 1H NMR (CDCl3) δ 0.70-0.74 (m, 1 H),
;
0.85-0.88 (m, 1 H), 1.00-1.04 (m, 1 H), 1.09-1.15 (m, 1 H),
1.24-1.72 (m, 20 H), 2.02-2.14 (m, 2 H), 2.58-2.86 (m, 7 H),
2.87-3.18 (m, 4 H), 3.68-3.85 (m, 9 H), 4.11-4.14 (m, 1 H),
4.60 (m, 0.5 H), 4.65 (m, 0.5 H), 6.79-6.83 (d, J ) 7 Hz, 2 H),
7.11-7.14 (t, J ) 7 Hz, 1 H), 7.24-7.46 (m, 8 H, signal +
solvent), 8.96 (m, 1 H); 13C NMR (CDCl3) δ 28.1, 28.3, 28.4,
30.5, 30.8, 34.1, 36.4, 36.6, 42.2, 42.3, 50.5, 50.6, 50.9, 55.1,
58.1, 58.3, 64.7, 64.9, 72.1, 79.0, 90.4, 106.0, 106.7, 109.2, 120.5,
122.2, 127.0, 127.7, 128.3, 128.9, 137.9, 139.1, 142.0, 155.5,
165.2, 165.5, 169.0. HRMS (FAB) calcd for C36H48N3O6 (M+):
618.3543. Found: 618.3551.
N. En a m in e (34). A solution of 10% HCl (aqueous) in
acetonitrile (1:1, 30 mL) was deoxygenated with a stream of
nitrogen for 15 min. The solution was cooled to 0 °C and added
to the NH cleavamines 33, under nitrogen, at 0 °C. The
mixture was stirred for 75 h at -10 °C in the dark, poured
onto crushed ice, and made basic with saturated ammonium
hydroxide. The resulting basic suspension was extracted with
dichloromethane (5 × 5 mL), and the combined organic
extracts were washed with brine (15 mL), dried over sodium
sulfate, and concentrated under reduced pressure below 40 °C
to give the enamine 34 as a pale-yellow foam (0.467 g, 0.999
mmol, 91%). Because it is sensitive, the enamine was used
directly in the following rearrangement step without further
purification. UV (EtOH) λmax 206, 228, 286 nm; IR (NaCl, thin
film) νmax 3375, 3054, 2924, 2846, 1731, 1692, 1589, 1482, 1462,
1435, 1393, 1365, 1337, 1305, 1249, 1220, 1166, 1073, 1050,
1011, 883, 741 cm-1; 1H NMR (CDCl3) δ 1.41-1.54 (m, 15 H),
1.58-1.61 (t, J ) 7 Hz, 1 H), 1.70-1.74 (m, 2 H), 1.80-1.85
(m, 1 H), 2.04-2.09 (m, 2 H), 2.10-2.14 (d, J ) 15 Hz, 2 H),
2.22-2.25 (t, J ) 7 Hz, 3 H), 2.48-2.55 (m, 4 H), 2.64-2.73
(m, 3 H), 2.77-2.93 (m, 7 H), 3.16-3.27 (m, 3 H), 3.29-3.32
(m, 2 H), 3.67 (s, 3 H), 3.73-3.74 (m, 1 H), 4.46-4.48 (d, J )
10 Hz, 1 H), 5.92 (s, 1 H), 7.07-7.09 (t, J ) 7 Hz, 1 H), 7.14-
7.17 (t, J ) 7 Hz, 1 H), 7.32-7.34 (d, J ) 7 Hz, 1 H), 7.48-
7.50 (d, J ) 7 Hz, 1 H); 13C NMR (CDCl3) δ 25.6, 28.5, 28.6,
L. N-Ben zylclea va m in es (32). The tetracycles 31 (0.168
g 0.272 mmol) were dissolved in glacial acetic acid (1.5 mL),
and the solution was heated to 90 °C. Sodium borohydride
(0.051 g, 1.4 mmol, 5.0 equiv) was added in portions to the
stirred mixture over a period of 15 min. The mixture was
poured onto crushed ice and made basic with saturated
ammonium hydroxide, and the resulting layers were sepa-
rated. The aqueous phase was extracted with dichloromethane
(4 × 10 mL). The combined organic layers were dried over
sodium sulfate, filtered, and concentrated to a gummy yellow
residue, which was purified by centrifugal chromatography on
silica gel, eluting with hexanes/ether (1:1) to yield the cleav-
amines 32 as a white foam (0.157 g, 0.253 mmol, 93%). TLC
Rf ) 0.60 (hexanes/ethyl acetate, 1:1, CAS yellow); UV (EtOH)
λmax 208, 228, 286 nm; IR (NaCl, thin film) νmax 3381, 3058,
3027, 2974, 2928, 1728, 1692, 1483, 1462, 1453, 1433, 1392,
1365, 1340, 1248, 1216, 1161, 1067, 1027, 923, 881, 771, 740,
701 cm-1; 1H NMR (CDCl3) δ 0.92-1.72 (m, 26 H), 1.95-2.04
(m, 2 H), 2.27-2.49 (m, 8 H), 2.59-2.65 (t, J ) 12 Hz, 2 H),
2.76-2.78 (d, J ) 10 Hz, 1 H), 2.83-2.91 (m, 4 H), 3.02-3.17
(m, 1.5 H), 3.17-29 (m, 0.5 H), 3.33-3.38 (m, 1 H), 3.49-3.55
(m, 4 H), 3.64-3.66 (d, J ) 12 Hz, 1 H), 3.74-3.94 (m, 7 H),
4.33 (d, J ) 4 Hz, 0.5 H), 4.50-4.51 (d, J ) 4 Hz, 0.5 H), 4.71-

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2727
32.6, 34.2, 38.4, 38.8, 39.8, 41.7, 49.0, 51.4, 52.1, 52.6, 78.9,
101.3, 110.6, 118.1, 119.0, 121.7, 127.3, 130.1, 133.8, 155.7,
175.1, 175.5; MS (CI, isobutane, 100 eV) m/z (rel intensity)
468 (M + 1+, 100), 410 (27), 368 (14), 324 (28), 265 (10).
yield 0.275 g of crude product. Centrifugal chromatography,
eluting with 10% methanol in dichloromethane, gave the title
product 19 as a yellow solid (0.143 g, 0.3714 mmol). The
product was recrystallized from methanol to give white crystals
(mp 175-176 °C). TLC Rf ) 0.30 (25% methanol in dichlo-
romethane, CAS yellow); UV (EtOH) λmax 208, 228, 286 nm;
IR (NaCl, thin film) νmax 3434, 3373, 3148, 3095, 3058, 3022,
2927, 2855, 2825, 2779, 1729, 1491, 1461, 1443, 1430, 1368,
1344, 1327, 1296, 1280, 1249, 1231, 1193, 1171, 1142, 1129,
1099, 1076, 1063, 1032, 1010, 973, 960, 926, 892, 857, 809,
O. 18-N-ter t-BOC-N-m eth ylcor on a r id in e (35). Crude
enamine 34 (0.408 g, 0.873 mmol) was dissolved in dry,
deoxygenated benzene (25 mL), and the mixture was heated
at reflux for 12 h in the dark. The solvent was removed under
reduced pressure, and the residue (0.494 g) was purified by
centrifugal chromatography, eluting with hexanes/ethyl ace-
tate (3:1) to yield the title product 35 as a white foam (0.218
g, 0.466 mmol, 53%). Recrystallization from ether gave white
crystals (mp 164-165 °C). TLC Rf ) 0.52 (hexanes/ethyl
acetate, 1:1, CAS blue-yellow); UV (EtOH) λmax 206, 228, 286
nm; 1H NMR (CDCl3) δ 1.13-1.23 (m, 1 H), 1.40-1.55 (m, 11
H), 1.61-1.73 (m, 2 H), 1.74-1.86 (m, 2 H), 1.87-1.98 (m, 2
H), 2.56-2.58 (d, J ) 13 Hz, 1 H), 2.80-2.96 (m, 5 H), 2.97-
3.07 (m, 1 H), 3.15-3.21 (m, 3 H), 3.26-3.35 (m, 1 H), 3.36-
3.46 (m, 1 H), 3.49-3.54 (m, 1 H), 3.71 (s, 3 H), 7.07-7.10 (t,
J ) 7 Hz, 1 H), 7.13-7.16 (t, J ) 7 Hz, 1 H), 7.23-7.25 (d, J
) 7 Hz, 1 H), 7.46-7.48 (d, J ) 7 Hz); 13C NMR (CDCl3) δ
14.0, 22.7, 27.3, 28.5, 29.7, 31.9, 34.0, 34.8, 36.5, 51.6, 52.6,
53.2, 54.9, 58.1, 60.3, 79.1, 110.3, 118.4, 119.3, 122.0, 128.8,
135.5, 136.4, 155.7, 171.1, 175.4; MS (CI, isobutane, 100 eV)
m/z (rel intensity) 469 (M + 2+, 34), 468 (M + 1+, 100), 412
1
738, 661 cm-1; H NMR (CDCl3) δ 1.13-1.18 (m, 1 H), 1.48-
1.54 (quint, J ) 7 Hz, 1 H), 1.60-1.67 (m, 1 H), 1.72-1.82 (m,
3 H), 1.85-1.95 (m, 3 H), 2.23-2.40 (m, 12 H), 2.52-2.58 (d,
J ) 14 Hz, 1 H), 2.79-2.81 (d, J ) 8 Hz,1 H), 2.90-2.93 (dt,
J ) 8, 3 Hz, 2 H), 2.98-3.04 (m, 4 H), 3.54 (m, 1 H), 3.72 (s,
3 H), 7.07-7.09 (t, J ) 7 Hz, 1 H), 7.12-7.16 (t, J ) 7 Hz, 1
H), 7.23-7.25 (d, J ) 7 Hz, 1 H), 7.47-7.48 (d, J ) 7 Hz, 1 H),
7.89 (br s, 1 H); 13C NMR (CDCl3) δ 21.9, 27.2, 31.6, 31.9, 35.2,
36.3, 45.1, 51.5, 52.5, 53.0, 53.3, 54.8, 57.2, 57.7, 110.1, 110.3,
118.3, 119.0, 121.8, 128.6, 135.4, 136.3; MS (CI, isobutane, 100
eV) m/z (rel intensity), 382 (M + 1+, 83), 337 (13), 323 (73),
278 (16), 150 (20), 123 (22), 102 (27), 93 (47), 83 (100). HRMS
(FAB, 3-NBA/Gly/TFA) calcd for
C23H32N3O2: 382.2494.
Found: 382.2480. For 13C isotope peak, calcd: 383.2528.
Found: 383.2512. HPLC: (a) silica C5, 43 bar, 1 mL/min,
hexane/2-propanol/triethylamine (3:1:0.04), injection in 20 µL
of 2-propanol, retention time of 18.04 min; (b) Cyclobond I
2000, 99 bar, 2 mL/min, hexane/ethanol/triethylamine (60:40:
0.2), injection in 20 µL of EtOH, retention time of 5.66 min.
(27), 323 (7). HRMS (FAB, 3-NBA/Gly/TFA) calcd for C27H38
-
N3O4: 468.2862. Found: 468.2888. For 13C isotope peak,
calcd: 469.2896. Found: 469.2922.
P . 18-Meth yla m in ocor on a r id in e (18). The preceding
compound 35 (0.647 g, 1.38 mmol) was dissolved in dry
methanol (60 mL). Anhydrous ether saturated with dry
hydrogen chloride (4.0 mL) was added dropwise to the stirred
solution, and the resulting yellow solution was heated at reflux
for 4 h. The mixture was then poured onto crushed ice in a
15% solution of ammonium hydroxide in brine (40 mL). The
resulting basic mixture was extracted with dichloromethane
(5 × 25 mL). The combined organic extracts were washed with
brine (25 mL), dried over magnesium sulfate, and concentrated
to afford the amine 18 as a light-yellow powder, which was
recrystallized from 2-propanol to give light-yellow crystals (mp
208-210 °C). TLC Rf ) 0.17 (25% methanol in dichlo-
romethane, CAS yellow); UV (EtOH) λmax 206, 226, 286 nm;
IR (NaCl, thin film) νmax 3323, 3060, 3022, 2985, 2922, 2855,
2818, 2793, 1719, 1501, 1464, 1451, 1429, 1339, 1307, 1266,
1257, 1231, 1206, 1191, 1164, 1127, 1093, 1073, 1057, 1031,
Tota l Syn th esis of 15-Nor -18-m eth oxycor on a r id in e
(36). A. 4-(1,3-Dioxola n -2-yl)-6-m et h oxy-1-h exa n a l (38).
4-(1,3-Dioxolan-2-yl)-6-methoxy-1-hexene (37) (7.75 g, 41.6
mmol)5a was dissolved in 50% aqueous dioxane (1 L), and a
catalytic amount of osmium tetroxide (0.50 g, 2.0 mmol, 5 mol
%, toxic!) was added, followed by sodium periodate (17.8 g, 83.2
mmol, 2 equiv). The reaction mixture, initially black due to
the presence of osmium(0), turned to a thick, white, milky
suspension after 5 min. Stirring was continued for 24 h at room
temperature. The suspension was filtered, and the white
precipitate was washed with dichloromethane (2 × 100 mL).
The filtrate was concentrated to ca. 500 mL under reduced
pressure and extracted with dichloromethane (2 × 100 mL).
The combined organic layers were dried over sodium sulfate
and concentrated to an orange-yellow oil (5.953 g). Continuous
extraction of the aqueous layer for 12 h furnished additional
product (1.11 g) for a total yield (crude) of 90%. The aldehyde
can be distilled under vacuum to give a colorless oil (bp 98-
100 °C, 0.19 mmHg). TLC Rf ) 0.60 (hexanes/ethyl acetate,
1:1, 2,4-DNP, yellow); IR (NaCl) νmax 2930, 2886, 2835, 1722,
1477, 1462, 1453, 1439, 1394, 1274, 1209. 1194, 1131, 1153,
1120, 1032, 947, 735, 697 cm-1; 1H NMR (CDCl3) δ 1.57-1.64
(m, 1 H), 1.83-1.89 (m, 1 H), 2.34-2.38 (m, 1 H), 2.48-2.56
(m, 2 H), 3.31 (s, 3 H), 3.44-3.46 (t, J ) 7 Hz, 2 H), 3.81-3.95
(m, 4 H), 4.86-4.87 (d, J ) 3 Hz, 1 H), 9.69 (m, 1 H); 13C NMR
(CDCl3) δ 29.9, 34.7, 42.8, 58.3, 64.7, 64.9, 70.1, 105.3, 201.3.
B. Tetr a cycles 39. A mixture of N-benzylindoloazepine 30
(1.06 g, 3.17 mmol) and aldehyde 38 (0.60 g, 3.2 mmol) was
heated, neat, with stirring in an open flask for 30 min. Another
0.5 equiv of aldehyde (0.30 g, 1.6 mmol) was added, and
heating continued for another 30 min. The residue was cooled
to room temperature and dissolved in dichloromethane/
methanol (5:1, 30 mL). Sodium borohydride (0.25 g, 6.6 mmol)
was added in portions, with stirring, over 15 min to reduce
the excess aldehyde. Stirring was continued for 20 min, and
the mixture was poured into water (10 mL) and extracted with
ether (4 × 20 mL). The combined ether layers were dried over
sodium sulfate and concentrated to yield a yellow-orange
residue. Flash chromotography on silica gel, eluting with
hexanes/ethyl acetate (3:1), gave tetracycles 39, an inseparable
mixture of diastereomers, as a pale-yellow foam (1.22 g, 2.41
mmol, 76%). TLC Rf ) 0.33 (hexanes/ethyl acetate, 1:1, CAS
blue-yellow); UV (EtOH) λmax 212, 232, 302, 330 nm; IR (NaCl)
νmax 3380, 2885, 2806, 1678, 1611, 1478. 1437, 1384, 1345,
1010, 1003, 996, 983, 956, 929, 901, 866, 837, 734 cm-1 1H
;
NMR (CDCl3) δ 1.16-1.23 (m, 1H), 1.52-1.83 (m, 7 H), 1.88-
1.94 (m, 2 H), 2.45 (s, 3 H), 2.55-2.66 (m, 3 H), 2.80-2.82 (d,
J ) 8 Hz, 1 H), 2.91-2.93 (m, 1 H), 2.98-3.04 (m, 1 H), 3.14-
3.21 (m, 2 H), 3.35-3.43 (m, 1 H), 3.54 (s, 1 H), 3.71 (s, 3 H),
7.06-7.09 (t, J ) 7 Hz, 1 H), 7.12-7.15 (t, J ) 7 Hz, 1 H),
7.23-7.24 (d, J ) 7 Hz, 1 H), 7.46-7.48 (d, J ) 7 Hz, 1 H),
7.85 (s, 1 H); 13C NMR (CDCl3) δ 22.1, 27.4, 32.0, 34.2, 35.0,
36.4, 36.5, 49.7, 51.7, 52.6, 53.1, 55.0, 57.7, 110.4, 118.4, 119.3,
122.0, 128.8, 135.5, 136.3, 175.5; MS (CI, isobutane, 100 eV)
m/z (rel intensity) 368 (M + 1+, 100), 337 (4), 323 (9). HRMS
(FAB, 3-NBA/Gly/TFA) calcd for
C22H30N3O2: 368.2338.
Found: 368.2323. For 13C isotope peak, calcd: 369.2372.
Found: 369.2353. HPLC: (a) silica C5, 43 bar, 1 mL/min,
hexane/2-propanol/triethylamine (3:1:0.04), injection in 20 µL
of 2-propanol, retention time of 2.93 min; (b) Cyclobond I 2000,
169 bar, 3 mL/min, hexane/ethanol/triethylamine (50:50:1),
injection in 5 µL of EtOH, retention time of 6.28 min.
Q. 18-Dim eth yla m in ocor on a r id in e (19). Crude amine 18
(0.304 g, 0.827 mmol) was taken up in methanol (12 mL),
aqueous formaldehyde (37%, 1.5 mL) was added, and the
mixture was heated at reflux for 2 h. After the mixture was
cooled to room temperature, sodium borohydride (0.50 g, 13.2
mmol, 16 equiv) was added, in portions, to the stirred mixture.
The solvent was removed under reduced pressure to yield a
yellow-white solid residue, which was taken up in water (20
mL). The mixture was extracted with dichloromethane (5 ×
15 mL). The combined organic layers were dried over sodium
sulfate, filtered, and concentrated under reduced pressure to

2728 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
1294, 1279, 1250, 1205, 1088, 915, 746, 702 cm-1 1H NMR
Kuehne et al.
;
2.68 (m, 2 H), 2.77-87 (m, 2 H), 2.89 (s, 1.5 H), 2.91-2.93 (m,
0.5 H), 2.94-2.96 (m, 0.5 H), 2.98 (br s, 0.5 H), 3.03 (s, 1.5 H),
3.08-3.17 (m, 1 H), 3.21-3.24 (m, 1 H), 3.33-3.35 (m, 1 H),
3.38-3.44 (m, 1 H), 3.44-3.50 (m, 1 H), 3.60-3.66 (m, 1 H),
3.68-3.79 (m, 6 H), 3.83-3.88 (m, 0.5 H), 3.91-3.97 (m, 0.5
H), 4.57 (d, J ) 4 Hz, 0.5 H), 4.63-4.64 (d, J ) 4 Hz, 0.5 H),
5.43-5.47 (m, 1 H), 7.04-7.07 (t, J ) 7 Hz, 1 H), 7.10-7.13
(q, J ) 7 Hz, 1 H), 7.28-7.32 (m, 1 H), 7.47-7.49 (d, J ) 7
Hz, 1 H), 8.62 (br s, 0.5 H), 8.65 (br s, 0.5 H); 13C NMR (CDCl3)
δ 10.8, 13.9, 22.8, 23.7, 26.2, 26.6, 27.5, 33.2, 33.8, 35.6, 37.3,
38.6, 41.8, 42.0, 42.4, 49.6, 51.8, 54.8, 58.1, 64.2, 64.6, 68.0,
70.4, 71.4, 105.3, 105.8, 110.3, 114.5, 117.7, 118.7, 121.2, 127.8,
128.7, 130.7, 131.6, 135.7, 175.7; MS (CI, isobutane, 100 eV),
m/z (rel intensity) 417 (M + 1+, 0.9), 358 (2), 233 (100), 201
(11), 173 (11), 144 (1). HRMS (FAB) calcd for C23H33N2O5:
417.2389. Found: 417.2381.
(CDCl3) δ 1.34-1.40 (m, 3 H), 1.41-1.48 (m, 2 H), 1.48-1.79
(m, 10 H), 1.98-2.07 (m, 4 H), 2.12-2.16 (m, 1 H), 2.54-2.63
(m, 4 H), 2.65-2.66 (d, J ) 4 Hz, 1 H), 2.79-2.83 (m, 2 H),
2.86-2.89 (m, 3 H), 2.95-2.99 (m, 5 H), 3.16-3.25 (m, 7 H),
3.28-3.30 (m, 1 H), 3.30-3.35 (m, 2 H), 3.41-3.46 (m, 1 H),
3.59-3.63 (m, 5 H), 3.66-3.71 (m, 3 H), 3.73-3.81 (m, 12 H),
3.86-3.90 (m, 1 H), 4.19-4.24 (m, 2 H), 4.63-4.64 (d, J ) 3
Hz, 1 H), 4.67 (d, J ) 3 Hz, 1 H), 6.79-6.81 (m, 2 H), 6.82-
6.87 (q, J ) 8 Hz, 2 H), 7.04-7.05 (d, J ) 8 Hz, 1 H), 7.08-
7.09 (d, J ) 8 Hz,1 H), 7.11-7.15 (t, J ) 8 Hz, 2 H), 7.26-
7.29 (m, 5 H, signal + solvent), 7.32-7.35 (m, 6 H), 7.38-7.42
(m, 4 H), 8.85 (br s, 1 H), 8.94 (br s, 1 H); 13C NMR (CDCl3) δ
21.2, 22.0, 27.4, 27.6, 29.9, 37.8, 38.1, 40.4, 41.5, 42.9, 43.0,
50.5, 55.7, 58.1, 58.4, 64.7, 65.1, 68.6, 69.6, 71.9, 72.7, 91.1,
91.4, 104.8, 105.6, 109.3, 109.4, 120.8, 122.2, 122.4, 127.2,
127.8, 127.9, 129.0, 138.3,139.9, 143.4, 169.0; MS (CI, isobu-
tane, 100 eV), m/z (rel intensity), 506 (11), 505 (M + 1+, 43),
473 (4), 431 (3), 290 (7), 227 (10), 201 (8), 171 (9), 157 (37),
127 (60), 91 (94), 84 (100), 73 (77), 61 (35), 59 (41). HRMS
(FAB) calcd for C30H37N2O5: 505.2702. Found: 505.2702.
E. En a m in e 43. A solution of acetonitrile and 10% HCl (1:
1, 20 mL) was deoxygenated by bubbling nitrogen through the
solution for 15 min and then added, under nitrogen, to the
cleavamines 42 (0.845 g, 2.03 mmol). The solution was stirred
for 1 h at 25 °C in the dark and was then poured onto crushed
ice and made basic with saturated ammonium hydroxide (40
mL). The resulting white suspension was extracted with
dichloromethane (5 × 15 mL). The combined organic extracts
were washed with brine (20 mL), dried over sodium sulfate,
filtered, and concentrated (below 50 °C) to yield the enamine
43 (0.675 g, 1.90 mmol, 94%). Owing to the sensitivity of this
compound, it was used directly in the cyclization step without
further purification. TLC Rf ) 0.58 (ethyl acetate/hexanes, 4:1,
CAS blue); UV (EtOH) λmax 206, 294, 334 nm; IR (NaCl) νmax
3327, 2922, 2863, 1731, 1660. 1584, 1482, 1462, 1435, 1387,
1305, 1240, 1193, 1166, 1103, 1057, 1018, 959, 931, 870, 743
cm-1; 1H NMR (CDCl3) δ 1.43-1.46 (m, 1 H), 1.55-1.61 (m, 2
H), 1.63-1.72 (septet, J ) 7 Hz, 2 H), 1.73-1.79 (m, 2 H),
1.89-1.95 (m, 3 H), 2.00-0.05 (m, 1 H), 2.09-2.20 (m, 4 H),
2.23-2.27 (m, 1 H), 2.28-2.37 (m, 3 H), 2.46-2.60 (m., 4 H),
2.83-2.94 (m, 5 H), 3.02-3.04 (m, 2 H), 3.15-3.25 (m, 5 H),
3.29-3.42 (m, 10 H), 3.44-3.45 (m, 1 H), 3.49-3.54 (m, 3 H),
3.71-3.77 (m, 7 H), 3.79-3.81 (d, J ) 11 Hz, 1 H), 4.17-4.19
(d, J ) 11 Hz, 1 H), 5.86 (s, 1 H), 6.76-6.78 (d, J ) 7 Hz, 1 H),
6.88-6.91 (t, J ) 7 Hz, 1 H), 7.08-7.23 (m, 5 H), 7.28-7.31
(m, 1 H), 7.34 (s, 1 H), 7.48-7.51 (d, J ) 7 Hz, 1 H), 8.75 (br
s, 1 H), 10.24 (br s, 1 H); 13C NMR (CDCl3) δ 24.3, 26.6, 30.9,
33.5, 34.9, 37.2, 38.3, 39.4, 40.2, 41.6, 42.4, 44.2, 48.6, 50.9,
52.1, 52.7, 54.7, 58.4, 59.7, 65.2, 70.8, 71.0, 72.0, 72.2, 78.6,
90.6, 108.3, 110.4, 113.7, 119.1, 121.3, 121.8, 131.5, 135.3,
136.3, 137.8, 140.5, 141.0, 142.3, 153.8, 166.4, 170.4, 174.7,
184.1, 184.8; GC-MS (CI, methane, 100 eV), m/z (rel inten-
sity), 396 (M + C3H6+), 383 (M + C2H5+), 355 (M + 1+), 323,
309, 297.
C. N-Ben zylclea va m in es 40 a n d 41. To tetracycles 39
(4.244 g, 8.39 mmol), dissolved in glacial acetic acid (50 mL)
at ∼92 °C, sodium borohydride (0.95 g, 25.1 mmol, 3 equiv)
was added over a period of 20 min. The solution was cooled to
room temperature, poured onto crushed ice, and made basic
with saturated ammonium hydroxide (250 mL). The resulting
basic suspension was extracted with ether (5 × 100 mL). The
combined ether extracts were washed with brine (100 mL) and
dried over sodium sulfate to yield the crude product as a
viscous red oil (4.032 g). Flash chromatography on silica gel,
eluting with hexanes/ether (3:1), afforded the diastereomeric
products as a white foam (2.691 g, 5.30 mmol, 63%). TLC Rf
) 0.40 (ether/hexanes, 5:2, CAS yellow); UV (EtOH) λmax 232,
286 nm; IR (NaCl) νmax 3441, 3392, 3058, 3027, 2923, 2888,
2246, 1727, 1488, 1462, 1436, 1340, 1248, 1192, 1213, 1162,
1112, 1026 cm-1; 1H NMR (CDCl3) δ 1.33-1.36 (m, 3 H), 1.46
(m, 1 H), 1.73-1.78 (m, 2 H), 2.02-2.08 (m, 3 H), 2.31-2.36
(m, 2 H), 2.40-2.47 (m, 2 H), 2.51-2.63 (m, 3 H), 2.74-2.86
(3 H), 2.90-2.93 (2 H), 3.00-3.01 (2s, 3 H), 3.07-3.13 (m, 2
H), 3.26-3.35 (m, 1 H), 3.55-3.58 (m, 2 H), 3.64-3.68 (m, 2
H), 3.70-3.72 (m, 2 H), 3.75-3.79 (m, 4 H), 3.81-3.85 (m, 2
H), 4.51-4.53 (m, 1 H), 4.57-4.58 (m, 0.2 H), 5.57-5.60 (m, 1
H), 7.02-7.05 (t, J ) 7 Hz, 1 H), 7.07-7.10 (t, J ) 7 Hz, 1 H),
7.24-7.28 (m, 5 H, signal + solvent), 7.31-7.35 (m, 3 H), 7.41-
7.45 (m, 4 H), 8.66 (m, 1 H); 13C NMR (CDCl3) δ 25.1, 26.5,
29.7, 32.8, 33.5, 36.57, 37.8, 42.0, 42.4, 52.0, 56.3, 58.2, 60.7,
63.4, 64.5, 64.6, 64.8, 71.4, 105.5, 105.9, 110.4, 110.5, 117.8,
118.8, 121.2, 126.9, 127.9, 128.2, 129.6, 131.4, 135.7, 139.8,
176.0; MS (CI, isobutane, 100 eV), m/z (rel intensity) 508 (0.70),
507 (M + 1+, 4), 391 (33), 279 (24), 233 (80), 201 (15), 183 (14),
171 (19), 167 (38), 149 (77), 113 (44), 91 (11), 83 (20), 73 (100).
F . 15-n or -18-Meth oxycor on a r id in e (36). Enamine 43
(0.053 g, 0.15 mmol) was dissolved in dry, deoxygenated
toluene (10 mL), and the mixture was heated in the dark at
reflux for 24 h. The mixture was concentrated under reduced
pressure, and the residue was purified by flash chromatogra-
phy on silica gel, eluting with hexanes/ethyl acetate (4:1) to
yield product 36 as a white foam (0.034 g, 0.096 mmol, 64%).
The product can be recrystallized from ether to yield colorless
crystals (mp 110-111 °C). TLC Rf ) 0.43 (hexanes/ethyl
acetate, 3:1, CAS blue-yellow); UV (EtOH) λmax 206, 228, 286
nm; IR (NaCl) νmax 3446, 3367, 3054, 2955, 2926, 2853, 2303,
1719, 1488, 1462, 1435, 1382, 1366, 1344, 1304, 1265, 1236,
1212, 1193, 1172, 1125, 1111, 1083, 1056, 1011, 896, 807, 740,
D. Secon d a r y Clea va m in es 42. The mixture of diaster-
eomeric cleavamines 40 and 41 (0.434 g, 0.855 mmol) was
dissolved in glacial acetic acid (5 mL), and 10% palladium on
carbon (0.12 g, dry) was added. The reaction mixture was
degassed under high vacuum, and the system was purged with
nitrogen and then hydrogen. The mixture was stirred at 25
°C for 25 h under hydrogen (1 atm). The black suspension was
filtered through Celite, the filter cake was washed with
methanol (3 × 10 mL), and the filtrate was concentrated to
ca. 1/3 volume under reduced pressure. The concentrate was
poured onto crushed ice, made basic with saturated ammonium
hydroxide (15 mL), and extracted with dichloromethane (5 ×
5 mL). The combined organic extracts were washed with brine
(5 mL), dried over sodium sulfate, filtered, and concentrated
under reduced pressure to yield the secondary amines 42
(0.338 g, 0.809 mmol, 95%). TLC Rf ) 0.11 (ether/hexanes, 5:2,
CAS blue-yellow); UV (100% EtOH) λmax 244, 270, 298 nm; IR
(NaCl) νmax 3376, 2924, 2246, 1726, 1684, 1462, 1437, 1340,
1266, 1192, 1163, 1116, 1029, 946, 740 cm-1; 1H NMR (CDCl3)
δ 1.10-1.23 (m, 1 H), 1.24-1.35 (m, 1 H), 1.38-1.52 (m, 2 H),
1.60-1.68 (septet, J ) 7 Hz, 1 H), 1.93-2.06 (m, 3 H), 2.08-
2.14 (t, J ) 13 Hz, 1 H), 2.19-2.27 (q, J ) 13 Hz, 1 H), 2.60-
705 cm-1; H NMR (CDCl3) δ 1.64-1.75 (m, 5 H), 1.86-1.91
1
(m, 1 H), 2.21 (br s, 1 H), 2.41-2.42 (d, J ) 8 Hz, 1 H), 2.80-
2.83 (m, 1 H), 2.90-2.96 (m, 1 H), 3.19-3.24 (m, 1 H), 3.35 (s,
3 H), 3.40-3.47 (m, 2 H), 3.51-3.58 (m, 1 H), 3.72 (s, 3 H),
4.02 (br s, 1 H), 7.06-7.09 (t, J ) 7 Hz, 1 H), 7.11-7.25 (t, J
) 7 Hz, 1 H), 7.22-7.24 (d, J ) 7 Hz, 1 H), 7.46-7.48 (d, J )
7 Hz, 1 H), 7.87 (br s, 1 H); 13C NMR (CDCl3) δ 22.0, 26.4,
40.6, 43.9, 46.9, 49.6, 52.7, 58.5, 60.2, 66.4, 72.1, 111.7, 119.2,
121.6, 128.4, 135.0, 135.3, 175.3; MS (CI, isobutane, 100 eV),
m/z (rel intensity) 355 (M + 1+, 100), 323 (9), 296 (61), 233
(23), 171 (20), 147 (12), 129 (23). HRMS (FAB, 3-NBA/Gly/

18-Methoxycoronaridine Congeners
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13 2729
Alper, K. R., Glick, S. D., Eds.; Academic Press: San Diego, 2001;
Vol. 56, pp 1-333. (d) Lotsof, H. S. Rapid method for interrupting
the narcotic addiction syndrome. U.S. Patent 4,499,096, 1985.
Lotsof, H. S. Rapid method for interrupting the cocaine and
methamphetamine abuse syndrome. U.S. Patent 4,587,243,
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U.S. Patent 5,152,994, 1992.
TFA) calcd for C21H27N2O3: 355.2021. Found: 355.2017. For
13C isotope peak, calcd: 356.2055. Found: 356.2056. HPLC:
(a) silica C5, 34 bar, 1 mL/min, hexane/2-propanol/triethyl-
amine (98.5:1.5:1), injection in 20 µL of 2-propanol, retention
time of 8.88 min; (b) Cyclobond I 2000, 31 bar, 1 mL/min,
hexane/ethanol (95:5), injection in 20 µL of EtOH, retention
time of 6.46 min.
Biologica l Recep tor Stu d ies. Receptor functional analy-
ses were performed as previously described.12-14 Briefly,
human embryonic kidney 293 fibroblasts (HEK293, ATCC
CRL1573) were cultured in MEM supplemented with 10% fetal
bovine serum and 2 mM glutamine (Life Technologies). Cells
were plated at (2-3) × 104 cells per milliliter on poly-D-lysine
coated 35 mm nunc dishes. Cells were transfected with the
cDNA cells for nicotinic acetylcholine receptor (nAChR) sub-
units nAChR-a3 (accession no. L31621), nAChR-b4 (accession
no. U42976), and enhanced green fluorescent protein (EGFP,
10% of total cDNA) using the Lipofectamine PLUS method
(Life Technologies). We performed functional analyses between
12 and 36 h after transfection. Transfected cells were selected
for EGFP expression and examined by voltage-clamp recording
at -70 mV in the whole-cell configuration using an Axopatch
200B patch clamp amplifier (Axon Instruments). Thin-walled
borosilicate glasss microelectrodes (TW150F, World Precision
Instruments) had resistances of 3-5 MS when filled with an
internal solution containing the following: 135 mM CsCl, 10
mM CsF, 10 mM HEPES, 5 mM EGTA, 1 mM MgCl2, 0.5 mM
CaCl2, pH 7.2. Current responses were filtered at 1 kHz with
an eight-pole Bessel filter (Cygnus Technologies), digitized at
1 kHz, and stored on a Macintosh PowerPC-G3 computer using
an ITC-16 interface (Instrutech) under control of the data
acquisition and analysis program Synapse (Synergy Research).
Cells were continuously superfused with extracellular solution
containing the following: 150 mM NaCl, 3 mM KCl, 5 HEPES,
1 mM MgCl2, 1.8 mM CaCl2, 10 mM glucose, and 0.1 mg/mL
phenol red, pH 7.3. ACh stock was made up in extracellular
solution at 1 M. Compound stocks were made up in DMSO at
20 mM except compound 5, which was made up at 18 mM.
ACh and the various compounds were diluted 1 to 1000 in
extracellular solution immediately prior to use. The final
concentration of DMSO was 0.1%, which we found to have no
effect on its own. Control, ACh, and drug solutions were
applied to individual cells by rapid perfusion. Solutions were
driven by a syringe pump through a flowpipe having four
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of albifloranine and its anti-addictive congeners, including 18-
methoxycoronaridine. Tetrahedron 1999, 55, 9405-9425. (b)
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addictive efficacy, toxicity, and mechanism of action. Ann. N. Y.
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U. K.; Molinari, H. H. 18-Methoxycoronaridine, a non-toxic iboga
alkaloid congener: Effects on morphine and cocaine self-
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Brain Res. 1996, 719, 29-35. (b) Glick, S. D.; Maisonneuve, I.
M.; Hough, L. H.; Kuehne, M. E.; Bandarage, U. K. (()-18-
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a single common output of ap-
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(16) Kuehne, M. E.; Bohnert, J . C.; Bornmann, W. G.; Kirkemo, C.
L.; Kuehne, S. E.; Seaton, P. J .; Zebovitz, T. C. Biomimetic
syntheses of indole alkaloids. 11. Syntheses of â-carboline and
indoloazepine intermediates. J . Org. Chem. 1985, 50, 919.
(17) Bornmann, W. G.; Kuehne, M. E. A common intermediate
providing syntheses of ψ-tabersonine, coronaridine, iboxyphyl-
line, vinamidine, and vinblastine. J . Org. Chem. 1992, 57, 1752.
(18) Neumeyer, J . L.; Bidlack, J . M.; Zong, R.; Bakthavachalam, V.;
Gao, P.; Cohen, D. J .; Negus, S. S.; Mello, N. K. Synthesis and
opioid receptor affinity of morphinan and benzomorphan deriva-
tives: Mixed κ agonists and µ agonists/antagonists as potential
pharmacotherapeutics for cocaine dependence. J . Med. Chem.
2000, 43, 114-122. The following are Ki ( SE (nM) values,
shown there in Table 1. For U50,488, they are 220 ( 6, 2500 (
170, and 0.36 ( 0.06 for [3H]DAMGO, [3H]naltrindole, and [3H]-
U69,593, respectively. For EKC, they are 0.78 ( 0.1, 3.4 ( 0.4,
and 0.62 ( 0.11 for [3H]DAMGO, [3H]naltrindole, and [3H]U69,-
proximately 100 mm diameter. Rapid switching between
inputs was achieved using a set of upstream solenoid valves
(Lee Co.) under computer control. The rate of solution ex-
change was approximately 5 ms as determined from liquid
junction current measures.
Ack n ow led gm en t. HRMS data were provided by
the Washington University Chemistry Department
Mass Spectroscopy Facility. Elementary analyses were
obtained by Robertson Microlit Laboratories, Madison,
NJ . The chemical studies were supported by the Na-
tional Institutes of Health, National Cancer Institute,
with Grant CA R01 12010 (M.E.K.). Nicotinic receptor
studies were supported by NIDA Grants DA 03817 and
DA 07307 (S.D.G.). Inhibition of opioid binding was
supported by Grants R05 DA 00360 and DA 03742
(J .M.B.).
Refer en ces
(1) Glick, S. D.; Maisonneuve, I. M. Development of novel medica-
tions for drug addiction. The legacy of an African shrub. Ann.
N. Y. Acad. Sci. 2000, 909, 88-103.
(2) (a) Popik, P.; Layer, R. T.; Skolnick, P. 100 years of ibogaine:
Neurochemical and pharmacological actions of a putative anti-
addictive drug. Pharmacol. Rev. 1995, 47, 235. (b) Popik, P.;
Skolnick, P. Pharmacology of ibogaine and ibogaine related
alkaloids. In The Alkaloids; Cordell, G. A., Ed.; Academic
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Proceedings of the First International Conference. The Alkaloids;

2730 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 13
Kuehne et al.
593, respectively. For (-)-cyclazocine, they are 0.10 ( 0.03, 0.58
( 0.06, and 0.052 ( 0.001 for [3H]DAMGO, [3H]naltrindole, and
[3H]U69,593, respectively. For levorphanol, they are 0.21 ( 0.02,
4.2 ( 0.5, and 2.3 ( 0.3 for [3H]DAMGO, [3H]naltrindole, and
[3H]U69,593, respectively.
of the other compounds to test in this model, 18-methoxycoro-
naridine was one of the most potent whereas 18-hydroxycoro-
naridine was one of the least potent compounds at the R3â4 site.
The possibility of there being a correlation between the effects
of these compounds at R3â4 receptors and effects on responding
for water is therefore quite remote. Compounds 3, 4, 11, and 18
were also evaluated in a sucrose solution response and found to
show no significant effect. Also, 18-methoxycoronaridine (3) does
not affect food intake in rats.9
(19) It is extremely unlikely that the effects of these compounds on
drug self-administration are due to a nonspecific action (e.g., a
sedative effect). Neither 18-methoxycoronaridine (3) nor 18-
hydroxycoronaridine (4), or its hydroxyl derivatives,5a at the
same dosage (20 mg/kg), affected responding for a nondrug
reinforcer (water). Although we did not have sufficient quantities
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