Tricyclic cyanoguanidines: Synthesis, site of action and insecticidal activity of a novel class of reversible acetylcholinesterase inhibitors

Article abstract of DOI:10.1016/S0968-0896(01)00326-1

Bridged-tricyclic cyanoguanidines 1 were found to be active as insecticides. The preparation and structure-activity relationships of oxacyclic (X = O) and carbocyclic (X = CH₂) analogues of 1 is described. Compounds 1 were found to inhibit acetylcholinesterase with IC₅₀ values comparable to the organophosphate Paraoxon. Unlike organophosphates, cyanoguanidines 1 were shown to reversibly bind acetylcholinesterase. This mode of action is shared by the structurally-related natural product Huperzine A.

Full text of DOI:10.1016/S0968-0896(01)00326-1

Bioorganic & Medicinal Chemistry 10 (2002) 599–613
Tricyclic Cyanoguanidines: Synthesis, Site of Action and
Insecticidal Activity of a Novel Class of Reversible
Acetylcholinesterase Inhibitors
Bruce L. Finkelstein,* Eric A. Benner, Maura C. Hendrixson, Kevin T. Kranis,
James J. Rauh, Maya R. Sethuraman and Stephen F. McCann*
DuPont Crop Protection, Stine-Haskell Research Center, PO Box 30, Newark, DE 19714, USA
Received 23 June 2001; accepted 28 August 2001
Abstract—Bridged-tricyclic cyanoguanidines 1 were found to be active as insecticides. The preparation and structure–activity rela-
tionships of oxacyclic (X=O) and carbocyclic (X=CH2) analogues of 1 is described. Compounds 1 were found to inhibit acet-
ylcholinesterase with IC50 values comparable to the organophosphate Paraoxon. Unlike organophosphates, cyanoguanidines 1
were shown to reversibly bind acetylcholinesterase. This mode of action is shared by the structurally-related natural product
Huperzine A. # 2002 Elsevier Science Ltd. All rights reserved.
Introduction
We were interested in preparing novel insecticides which
might overcome some of the limitations of the organo-
phosphates and carbamates, particularly for the control
of homopteran pests. Screening of our compound col-
lection against Peregrinus maidis (corn planthopper) led
to the discovery of compound 1a as a lead structure
(Fig. 2). We report herein on the synthesis, site of action
and insecticidal activity of a novel class of insecticides.
Acetylcholinesterase (AChE) inhibitors are the most
widely used class of insecticides. All of the compounds
used today fall into two groups, organophosphates and
carbamates. Activity of these compounds results from
deactivation of the AChE enzyme by irreversible phos-
phorylation or slowly reversible carbamoylation of the
active serine hydroxyl.1 These compounds are effective
insecticides, but their extensive use for over 40 years has
given rise to strains of resistant insects. In addition, the
acute mammalian toxicity of some of these compounds
(particularly the organophosphates) has raised safety
concerns and many of these compounds are under
review by regulatory agencies.
Chemistry
The synthesis of bridged benzoxadiazocines 1 (X=O)
followed the procedure of Svetlik8 who originally
described the synthesis of 1a in 1988 (Scheme 1). In the
first step, Claisen-Schmidt condensation of salicylalde-
hyde and acetone gave the hydroxyphenyl-enone 2a.
Treatment of 2a with2 equiv of cyanamide and catalytic
piperidine in refluxing 1,2-dimethoxyethane gave 1a.
Recently there has also been much interest in antic-
holinergic compounds as therapies for cognitive disorders.2
To date, four drugs have been approved by the United
States Food and Drug Administration for treatment of
Alzheimer’s disease. These are tacrine,3 donepezil,4
galanthamine,5 and rivastigmine6 (Fig. 1). These com-
pounds all inhibit AChE, the first three of these do so
reversibly. The natural product Huperzine A shares this
mode of action and is currently the subject of clinical
studies towards the treatment of Alzheimer’s disease.7
Preparation of analogues 1 (X=O) withvariations in
the benzo substituent (Y), the bridgehead substituent
(R4), or the methano-bridge substituent (R1) involved
preparations of the appropriate a,b-unsaturated ketones
and aldehydes 2 as shown in Schemes 2 and 3.
In Scheme 2, Claisen-Schmidt condensation8,9 of a
ketone with a salicylaldehyde in the presence of NaOH
gave the (2-hydroxyphenyl) enones 2 in generally good
yields (highest for acetone). Alternatively, compounds 2
*Corresponding authors. Fax: +1-302-366-5738;
e-mail: bruce.l.finkelstein@usa.dupont.com; stephen.f.mccann@usa.
dupont.com
0968-0896/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(01)00326-1

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B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
Scheme 3. (a) Pd(OAc)2, NaHCO3, (n-Bu)4NI, DMF, 60 ꢀC (11–45%
yields).
Scheme 1. (a) H2NCN (2 equiv), piperidine (cat), DME, reflux (1a,
46%).
Scheme 4. (a) H2NCN (2 equiv), piperidine (cat), DME, reflux (3–
85% yields).
Scheme 2. (a) R1CH2C(O)R4, NaOH, H2O, rt (15–97% yields).
could be prepared by a tetrabutylammonium chloride
assisted10 Heck reaction11 of 2-iodo phenol with an a,b-
unsaturated ketone or aldehyde (Scheme 3). Table 1 lists
the compounds 2 that were prepared.
the presence of NaH (Scheme 5). In most cases, reaction
at N-3 was not observed, even in the presence of excess
electrophile and base. The exception was methyl iodide,
which, when used in excess and in the presence of >2
equiv of NaH, gave the dimethylated compound (1l) in
15% yield, along with 33% of the mono-methyl com-
pound (1g) (Scheme 6).
Cyclization of compounds 2 withcyanamide using the
procedure of Svetlik8 gave the benzoxadiazocines 1
(X=O) as shown in Scheme 4.
The regiochemical assignments of the products obtained
in the alkylations/acylations described in Schemes 5 and
6 were made by difference NOE experiments. For
example, the assignment of structure for 1f was made on
the basis of an observed NOE between the angular
methyl group and the N–H proton, while the regio-
chemistry of 1g was determined by observed NOE’s
between the angular methyl group and the N–H proton
as well as between the angular proton and the N-methyl
group (see Fig. 3).
2
Compounds 1 (X=O) withsubstitution at N-5 (R not
equal to H) were prepared by reaction of 1 (R2=H)
withan alkylating, acylating or sulfonylating agent in
Table 2 lists the bridged-benzoxadiazocines 1 (X=O)
which were prepared using the methods described in
Schemes 4–6.
Bridged-benzodiazocines 1 (X=CH2) were prepared by
cyclization of the appropriate cis 1,2,3,4-tetrahydro-
naphthalene-1,3-diamine with diphenyl cyanocarboni-
midate. The diamines were prepared by the method of
Shiotani and Mitsuhashi12 (Scheme 7). In the instances
were diastereomers were obtained they were separated
at the lactam stage. The relative configurations were
determined by NOE difference experiments. Benzodia-
zocines 1 (X=CH2) that were prepared and tested for
insecticidal activity are shown in Table 3.
Figure 1. Acetylcholinesterase (AChE) inhibitors.
Figure 2.

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
601
Scheme 5. (a) NaH (1.1 equiv), R2-X, (1.1 equiv), DMF, rt.
Scheme 7. (a) H2SO4; (b) MeOH, HCl, reflux; (c) NH2OH; (d) H2 (50
psi), PtO2, MeOH; (e) 120 ꢀC, 4 h; (f) separate diastereomers (when
R1, R3 other than H); (g) HCl, reflux; (h) HN3; (i) (PhO)2C=NCN, i-
PrOH, reflux.
BPH and GLH, along withthe combined contact/sys-
temic activity data for the compounds versus CPH. It is
apparent from the data in Table 2 that substitution on
the benzo-ring (Y-group) lowers the insecticidal activity
of compounds 1. Except for cases where Y=9-F (1q,
1ac, 1ao, and 1ap) or 9-Cl (1s), all examined substitution
patterns for Y (other than H) gave compounds that
Scheme 6. (a) NaH (2.2 equiv), MeI, (4 equiv), DMF, rt.
Results and Discussion
Insecticidal activity
Cyanoguanidines 1 were tested for insecticidal activity
against corn planthopper (CPH) (Peregrinus maidis),
brown planthopper (BPH) (Nilaparvata lugens), and
green leafhopper (GLH) (Nephotettix cincticeps). The
latter two species are economically-important rice pests.
All three species belong to the order Homoptera and, as
such, typically feed upon the phloem or xylem sap of the
host plant. Due to this feeding characteristic, it is
advantageous to use systemic-acting insect control
agents to combat Homopteran pest insects. In this way,
the insect is exposed to the control agent when it feeds
upon the plant sap. Another advantage to using sys-
temic insecticides is that they can be applied to the soil
where they are taken-up by the plant roots, obviating
the need for a spray application.
Table 1.
Compd
Y
R1
R4
%Yield
mpꢀC
2a
2b
2c
2d
2e
2h
2m
2n
2o
2p
2s
2t
2v
2x
2aa
2ab
2ac
2aj
2ak
2al
2an
2aq
H
5-Cl
H
H
H
H
H
H
H
CH3
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
C2H5
CH3
C2H5
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
76
88
95
97
96
48
77
15
83
94
84
89
93
82
77
85
86
31
45
14
11
32
136–138
157 (dec)
141–145
149–151
86–90
114–116
115–117
93–94
141–143
151–155
125–130
130–133
161–162
142–144
136–137
187–190
126–130
n.d
3,5-di-Cl
3,5-di-Br
5-NO2
H
5-OCF3
H
3-CH3
3,5-di-t-Bu
4-Cl
5- CH3
3-F
The active analogues 1 typically displayed greater
activity via systemic application than by contact (spray)
application, although in most cases some degree of
contact activity was also observed. Tables 2 and 3 sum-
marize the systemic activity for compounds 1 versus
3,4-di-O CH3
6-OCH3
4,6-di-Cl
4-F
H
H
H
H
C2H5
CH3
C2H5
CH3
CH3
H
H
CH3
n.d.
n.d.
n.d.
n.d.
H
nd, not determined.
Figure 3. Observed NOE’s for 1f and 1g.

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B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
were inactive at the highest test concentrations (100
ppm for BPH and GLH, 250 ppm for CPH).
For compounds 1 where R1=Me, exo- orientation of
the bridgehead methyl group (relative to the guanidine
moiety) gave higher activity than endo- (see e.g., 1aq vs
1ar, 1au vs 1at and 1az vs 1ay). Exo-methyl substitution
on the bridgehead carbon gave higher activity than no
Compounds where X=CH2 (in Table 3) were somewhat
more active than analogous X=O compounds (Table 2).
Table 2. Compounds 1 (X=O)
Insecticidal activityg
Compd
Y
R1
R2
R3
R4
% Yielda
Mp (ꢀC)
BPH
GLH
CPH
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
1o
1p
1q
1r
1s
1t
1u
1v
1w
1x
1y
1z
1aa
1ab
1ac
1ad
1ae
1af
1ag
1ah
1ai
1aj
1ak
1al
1am
1an
1ao
1ap
1aq
1ar
H
8-Cl
8,10-di-Cl
8,10-di-Br
8-NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
H
H
H
H
H
CH
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
C2H5
CH3
Ph85
CH3
CH3
CH3
C2H5
CH3
CH3
CH3
63
32
19
16
271–273h
264–266
288–290
284 (dec)
>225
219–221
>220
240–245
238–240
++
À
++
À
+++
À
À
À
À
À
À
À
H
C(O)CH3
CH3
H
SO2CH3
H
CO2CH3
CH3
H
18
À
À
À
73c
40c
36
++
++
++
À
++
++
+
À
+++
+
+
H
H
H
H
13c
À
253–256
À
À
À
12c
15c
48
10
46
199 (dec)
187 (dec)
288–289
249–252
279 (dec)
320–321
207–210
>225
>225
>225
>225
>225
++
++
À
++
++
À
++
++
À
H
8-OCF3
H
10-CH3
8,10-di-t-Bu
9-F
H
9-Cl
8-CH3
H
10-F
H
9,10-di-OCH3
b
H
H
À
À
À
À
À
À
H
C(O)CH3
CH2PhH
H
H
C2H5
H
2-CH2-pyridyl
H
allyl
CH2SiMe3
H
28
À
À
À
6d
À
À
À
80c
50
À
À
À
3
CH3
+
+
À
À
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
CH3
H
CH3
H
CH3
CH3
CH3
CH3
58
À
À
16c
43
++
À
+
À
++
À
75c
12
>225
>225
+
À
À
À
À
À
H
38c
14c
46
208–210
186–189
>225
280–282
>225
+
+
À
++
+
H
7-OCH3
7,9-di-Cl
9-F
H
H
H
H
H
8-NH2
H
H
H
H
À
À
À
À
H
59
60
À
À
À
H
CH2CO2Me
propargyl
C(O)CH2CH3
C(O)n-Pr
C(O)i-Pr
++
+
++
À
++
+
13c
60c
60c
72c
21c
55e
5
>225
204 (dec)
196–198
198–199
206–209
234–235
205–210
219–221
Oil
Oil
249–252
>225
209–211
248–9
279–280
++
++
++
++
À
+
++
+
+
À
+
++
À
+
H
H
H
H
H
À
+
++
À
À
Etb
CH3
H
3
14
2c
À
À
b
H
C(O)CF3
H
CH3
CO2CH3
H
+
À
++
À
++
À
H
Etb
H
7
À
À
À
9-F
9-F
H
10d
14d
nd
nd
nt
nt
+
+
H
exo-CH3
endo-CH3
nt
+++
+
nt
f
++
À
+++
+
f
H
H
aYields of chromatographically homogeneous products after purification.
bProduct isolated as a mixture of exo- and endo-isomers.
cYield starting from 1a.
dYield starting from 1ac.
eYield starting from 1e.
fRelative to the guanidine-containing ring.
gInsecticidal activities refer to the following approximate LC80 values: BPH or GLH: ‘À’=>100ppm, ‘+’=<100ppm, ‘++’=<10ppm,
‘+++’=<1ppm, ‘++++’=<0.1ppm; CPH: ‘À’=>250ppm, ‘+’=<250ppm, ‘++’=<50ppm, ‘+++’=< 10ppm, ‘++++’=<2.5 ppm.
hFrom ref 8a.

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
603
substitution (see e.g., 1aq vs 1a, 1al vs 1aj and 1au vs
1as). Ethyl bridgehead substitution decreased actitivity
(see 1ak vs 1a and 1an vs 1aj).
bition remaining constant at about 50% regardless of
incubation time. This is consistent with an equilibrium
(reversible) inhibition mechanism. Similar results were
observed for 1a withAChE from SCRW (Fig. 4) and
GLH (Fig. 5), indicating a similar mechanism of inhi-
bition occurs in eachinsect.
2
In general, compounds 1 withR =Me, COR or CO2R
had about the same level of activity as the unsubstituted
compounds. Allyl, propargyl as well as larger alkyl sub-
stituents (i.e., larger than ethyl) gave compounds that
were less active, while benzyl, trifluoroacetyl and methane-
sulfonyl substitution resulted in a loss of activity. In the
case of benzoxadiazocines (X=O), the only compound
Since AChE is a soluble enzyme, reversibility of enzyme
inhibition by 1a was further demonstrated through the
use of molecular size exclusion chromatography (Fig.
6). If inhibition is a reversible phenomenon, then mole-
cular size chromatography should separate a small
molecule inhibitor from the large AChE enzyme. To test
this experimentally, SCRW AChE was pre-incubated
3
prepared withR substitution, 1l, had about the same
level of activity as the protio-analogue 1g. For the ben-
zodiazocines (X=CH2), R3 substitution resulted in a
decrease in activity (see e.g., 1ax vs 1as and 1aw vs 1as).
Methyl substitution at R4 was preferred for maximum
insecticidal activity for 1 where X=O. When R4 was
either H or Et, activity decreased while Ph substitution
at R4 resulted in inactive compounds. For compounds 1
where X=CH2, substitutents R4=H or CH3 gave com-
parable activity.
Reversible AChE inhibition analogous to huperzine A
The bridged-bicyclic cyanoguanidines 1 inhibit insect
AChE in a reversible manner, similar to huperzine
A.13,14 Time course AChE inhibition studies using
enzyme from southern corn rootworm (SCRW) (Dia-
brotica undecimpunctata) (Fig. 4) or GLH (Fig. 5)
demonstrate the contrasting inhibition mechanisms
exhibited by 1a versus paraoxon. When AChE from
either insect was incubated for 120 min with a con-
centration of paraoxon which normally inhibits AChE
by 50% after a 30 min exposure, enzyme inhibition
continued to increase and approached 100%, typical of
an irreversible inactivation mechanism. Comparable
incubations of AChE with 1a resulted in enzyme inhi-
Figure 4. Time-course of inhibition of AChE from Southern corn
rootworm (Diabrotica undecimpunctata) by 1a or paraoxon. AChE
from Southern corn rootworm was incubated for up to 120 min with 2
mM 1a or 300 nM paraoxon. The concentrations chosen were
approximately equal to the I50 measured for eachcompound in dose–
response experiments. The control AChE preparation was incubated
similarly, except for the lack of exposure to either compound. Each
data point represents the mean of triplicate determinations. The SEM
was typically less than 5%.
Table 3. Compounds 1 (X=CHR5)
Insecticidal activitya
Cmpd
R1
R2
R3
R4
R5
MpꢀC
BPH
GLH
CPH
1as
1at
H
endo-CH3
exo-CH3
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3
H
H
H
H
H
CH3
H
H
250
+
+
++
nt
+++
++
++++
nt
++
nt
++
À
b
254–256
286–287
218–220
225–227
234–238
272–273
250–255
b
1au
1av
1aw
1ax
1ay
1az
H
C(O)CH3
++++
+
+
H
C(O)CH3
H
H
H
H
H
H
À
H
H
H
nt
À
H
exo-CH3
+++
nt
++
nt
+++
++++
b
aInsecticidal activities refer to the following approximate LC80 values: BPH or GLH: ‘À’=>100 ppm, ‘+’=<100 ppm, ‘++’=<10 ppm,
‘+++’=<1 ppm, ‘++++’=<0.1 ppm; CPH: ‘À’=>250 ppm, ‘+’=<250 ppm, ‘++’=<50 ppm, ‘+++’=<10 ppm, ‘++++’=<2.5
ppm, nt=not tested.
bRelative to the guanidine-containing ring.

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B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
for 30 min at room temperature witheither paraoxon or
1a (at 1 or 10 mM, respectively), or DMSO (solvent
control). The enzyme-inhibitor and enzyme-solvent
control mixtures were loaded onto identical Sephadex
G-25-300 columns and eluted withbuffer as indicated.
Fractions were collected, aliquots added to assay tubes
and the standard AChE assay was run without any fur-
ther incubation. The aliquots of the column fractions
thus served as the only potential source of AChE pre-
sent in the assay tubes. Therefore, detection of enzyme
activity is an indication of non-inhibited AChE being
present in the column fraction. The reversible nature of
the AChE inhibition by 1a was evident by the recovery
of approximately equal amounts of enzyme activity
from all fractions off the columns containing 1a-treated
AChE and the DMSO-treated AchE (see Fig. 6). In
contrast, the paraoxon-treated AChE appeared to be
irreversibly inactivated, as less than 20% of the control
level of activity was recovered from the column.
differ in regard to the orientation of the cyanoguani-
dine. In Figure 7a, the cyano nitrogen of 1a is postu-
lated to occupy the region of space that is occupied by
water 618 in the AChE–HupA crystal structure complex
(Z-configuration). In Figure 7b, the cyano group is
rotated approximately 180ꢀ about the double bond,
placing the cyano nitrogen in the region of space occu-
pied by the oxygen atom of the Huperzine pyridone (E-
configuaration).
In these figures, good overlap can be seen between the
bicyclic ring systems. In addition, the nitrogen of the
cyanoguanidine moiety of 1a lines up nicely withthe
nitrogen of the pyridone ring of Huperzine A. These
modeling studies combined withthe similarity in profile
of enzyme inhibition for the two molecules suggest that
they may share the same binding site in the enzyme. In
addition these overlaps imply that the benzene ring and
oxygen atoms of compound 1a may not be essential
features and that substitution on the bridging methylene
of compound 1a may be desirable.
Modeling studies
Molecular modeling studies were carried out to investi-
gate the structural similarity between Huperzine A and
compound 1a. Bothmolecules are fairly rigid and share
a common shape of bridged bicyclic structures. To
investigate the potential binding mode of 1a, manual
docking studies were performed using the AchE–HupA
crystal15 structure complex. Huperzine A was removed
from the AchE–HupA crystal structure complex and
replaced witha model of 1a. Two potential binding
modes were determined and the results are presented in
Figure 7a and b in terms of the overlap with bound
Huperzine-A. The three main factors used to guide the
docking process were overall shape complementarity,
establishing polar interactions with residues Tyr 130
and Glu 199 and forming hydrophobic contacts with
Phe 330, 331, 290. The two binding modes presented
In fact, it is interesting to note that some of the most
active analogues 1 (as AChE inhibitors or versus
insects) contain substitution on the bridging methylene
group (R1 other than H). (See, for example, compound
1aq in Table 2 and 1au and 1az in Table 3.) It is inter-
esting that when R1=Et, insecticidal activity decreased
(see 1ak and 1an in Table 2). Since Huperzine A con-
tains an ethylidine substituent at the bridgehead posi-
tion, we would like to investigate the activities of
structures 1 that also contain a bridgehead ethylidene
substituent (synthesis efforts towards these analogues
are currently underway).
Figure 6. Molecular size-exclusion chromatography of AChE from
Southern corn rootworm (Diabrotica undecimpunctata) treated with 1a
or paraoxon. Identical Sephadex G-25-300 columns were poured with
bed volumes of approximately 10 mL. The columns were equilibrated
with 0.1 M sodium phosphate, pH 7.4. Next, a 3 mL aliquot of AChE
was mixed with 1a (10 mM final concentration), paraoxon (1 mM final
concentration) or dimethyl sulfoxide (solvent control). The enzyme-
inhibitor mixture was incubated for 30 min at 23 ꢀC. Following incu-
bation, 2 mL of eachmixture was loaded onto separate columns and
eluted with sodium phosphate buffer. Five 2 mL fractions were col-
lected with20 mL aliquots taken from eachfraction and assayed in the
standard AChE assay. AChE assay conditions were identical to that in
Methods except: no additional solvent or compound was added to the
well, 190 mL of buffer was used, the microplate was not incubated
prior to ATC/DTNB addition.
Figure 5. Time–course inhibition of AChE from Green leafhopper
(Nephotettix cincticeps) by 1a and paraoxon. AChE from Green leaf-
hopper was incubated for up to 120 min with 3 mM 1a or 1 mM para-
oxon. The concentrations chosen were approximately equal to the I50
measured for eachcompound in dose–response experiments. Teh
control AChE preparation was incubated similarly, except for the lack
of exposure to either compound. Each data point represents the mean
of triplicate determinations. The SEM was typically less than 5%.

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
605
Conclusions
Tricyclic benzodiazocines 1 are a novel class of insect
control compounds which display activity towards a
variety of economically-important rice hopper species.
The structure–activity relationships of substituents
around the tricyclic nucleus of 1 was limited to either
hydrogen or methyl groups for R1, R4, and R5 for
highest insect activity. Benzodiazocines 1 (X=CH2)
were somewhat more insecticidally active than analo-
gous benzoxadiazocines 1 (X=O). In general, higher
insecticidal activities of compounds 1 corresponded to
lower IC50 levels in AChE assays, indicating cholines-
terase inhibition as the primary mode of insecticidal
action. The compounds 1 were found to inhibit
AChE in a reversible manner, analogous to structu-
rally-related Huperzine A. Molecular overlays of 1a
with Huperzine A show significant homology between
the two structures. It is not currently known whe-
ther compounds
1 function pharmacologically as
cognition enhancers in mammals, analogous to
Huperzine A.
Experimental
General methods
1H NMR spectra were recorded using a Varian Unity
Plus300-NB spectrometer (300 MHz) in the solvent
indicated. Coupling constants are reported in hertz.
Spectral data for minor isomers in a product mixture
are indicated in parentheses. IR spectra were recorded
using a Perkin-Elmer 1600 FTIR instrument. Elemental
analyses were performed by Quantitative Technologies,
Inc., Whitehouse NJ, USA. Thin-layer chromatography
(TLC) was carried out using Whattman silica gel 60A
plates. Silica gel (flash) chromatography was performed
using EM Science silica gel 60 (230–400 mesh). All
reactions were carried out under a positive pressure of
nitrogen using reagent grade or anhydrous solvents as
received.
Figure 7. (a) Overlap of Compound 1a (green) and Huperzine A (sil-
ver) withZ-configuration assumed for double bond. (b) Overlap of
Compound 1a (green) and Huperzine A (silver) withE-configuration
assumed for double bond.
1
4-(5-Chloro-2-hydroxy-phenyl)-but-3-en-2-one (2b). H
NMR (DMSO-d6) d 2.30 (s, 3H), 6.90 (d, 1H, J=9.3
Hz), 6.94 (s, 1H), 7.26 (dd, 1H, J=9.3, 2.2, Hz), 7.67 (d,
1H, J=4.5 Hz), 7.70 (d, 1H, J=9.3 Hz), 10.54 (s, 1H).
4-(3,5-Dichloro-2-hydroxy-phenyl)-but-3-en-2-one (2c).
1H NMR (DMSO-d6) d 2.33 (s, 3H), 6.93 (d, 1H,
J=16.5 Hz), 7.58 (d, 1H, J=2.3 Hz), 7.74 (d, 1H,
J=2.6 Hz), 7.75 (d, 1H, J=16.5, Hz), 10.39 (br s, 1H);
IR (KBr pellet) 3220, 1660, 1648, 1623, 1462, 1253, 980
cmÀ1. Anal. calcd for C10H8Cl2O2: C, 51.98; H, 3.49.
Found: C, 51.78; H, 3.46.
Procedure A: preparation of compounds 2. The prepara-
tion of 4-(2-hydroxy-phenyl)-but-3-en-2-one (2a) h as
been previously described8 and is representative. Aqu-
eous sodium hydroxide solution (1.0 N, 18.0 mL, 18.0
mmol) was added to a solution of salicylaldehyde (2.0 g,
16.4 mmol) and acetone (12 mL, 164 mmol) at room
temperature (slight exotherm to 27 ꢀC). The resulting
yellow solution was stirred at room temperature for 14
h, at which time the resulting dark brown mixture was
acidified by dropwise addition of aqueous HCl (1.0 N,
23 mL, 23 mmol) at <10 ꢀC. The resulting yellow solid
was isolated by filtration and dried under vacuum to
4-(3,5-Dibromo-2-hydroxy-phenyl)-but-3-en-2-one (2d).
1H NMR (DMSO-d6) d 2.32 (s, 3H), 6.90 (d, 1H,
J=16.5 Hz), 7.76 (d, 1H, J=16.5 Hz), 7.80 (d, 1H,
J=2.3, Hz), 7.88 (d, 1H, J=2.3, Hz), 10.25 (br s, 1H).
Anal. calcd for C10H8Br2O2: C, 37.54: H, 2.52. Found:
C, 37.61; H, 2.48.
1
1
give 2.0 g of 2a (76% yield). H NMR (DMSO-d6) d
4-(2-Hydroxy-5-nitro-phenyl)-but-3-en-2-one (2e). H
2.30 (s, 3H), 6.81 (distorted d, 1H, J=5.7 Hz), 6.85 (m,
1H), 6.92 (d, 1H, J=8.4 Hz), 7.24 (td, 1H, J=8.1 2.4,
Hz), 7.60 (d, 1H, J=8.1 Hz), 7.78 (d, 1H, J=16.2 Hz),
10.3 (s, 1H).
NMR (DMSO-d6) d 2.34 (s, 3H), 7.05 (d, 1H, J=16.5,
Hz), 7.10 (d, 1H, J=9.6 Hz), 7.74 (d, 1H, J=16.5 Hz),
8.15 (dd, 1H, J=7.5, 2.9 Hz), 8.51 (d, 1H, J=2.9 Hz),
11.9 (br s, 1H); IR (KBr pellet) 3076, 1637, 1607, 1519,
1496, 1345, 1306, 981 cmÀ1. Anal. calcd for C10H9NO4:
C, 57.97; H, 4.38; N, 6.76. Found: C, 57.64; H, 4.33; N,
6.55.
Using the appropriately substituted salicylaldehydes,
the following compounds were similarly prepared.

606
B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
1-(2-Hydroxy-phenyl)-pent-1-en-3-one (2h). Prepared
following Procedure A using 2-butanone in place of
acetone. H NMR (CDCl3) d 1.19 (t, 3H, J=7.2 Hz),
(s, 1H). Anal. calcd for C11H12O3: C, 68.74; H, 6.29.
Found: C, 68.25; H, 6.16.
1
2.75 (q, 2H, J=7.2 Hz), 6.89 (m, 2H), 6.99 (d, 1H,
J=16.5 Hz), 7.26 (d(apparent)t, 1H, J=7.8, 1.2, Hz),
7.48 (d, 1H, J=7.8 Hz), 7.91 (d, 1H, J=16.5 Hz).
4-(2,4-Dichloro-6-hydroxy-phenyl)-but-3-en-2-one (2ab).
1H NMR (DMSO-d6) d 2.32 (s, 3H), 6.97 ((apparent)s,
1H), 7.16 ((apparent)s, 1H), 7.18 (d, 1H, J=16.5 Hz),
7.69 (d, 1H, J=16.5 Hz).
4-(2-Hydroxy-5-trifluoromethoxy-phenyl)-but-3-en-2-one
1
1
(2m). H NMR (DMSO-d6) d 2.31 (s, 3H), 6.95 (d, 1H,
4-(4-Fluoro-2-hydroxy-phenyl)-but-3-en-2-one (2ac). H
J=16.0 Hz), 6.99 (d, 1H, J=9.0 Hz), 7.25 (dd, 1H,
J=9.0, 2.5 Hz), 7.65 (d, 1H, J=2.5 Hz), 7.72 (d, 1H,
J=16.0 Hz); IR (KBr pellet) 3020, 1638, 1429, 1261,
1212, 979 cmÀ1. Anal. calcd for C11H9F3O3: C, 53.67;
H, 3.68. Found: C, 53.83; 3.57.
NMR (DMSO-d6) d 2.30 (s, 3H), 6.60–6.75 (m, 2H),
6.81 (d, 1H, J=16.5 Hz), 7.60–7.70 (m, 1H), 7.72 (d,
1H, J=16.5 Hz), 10.70 (s, 1H). Anal. calcd for
C10H9FO2: C, 66.67; H, 5.03. Found: C, 66.68; H,
4.97.
1-(2-Hydroxy-phenyl)-2-methyl-pent-1-en-3-one (2n).
Prepared following Procedure A using 3-pentanone in
place of acetone. 1H NMR (CDCl3) d 1.18 (t, 3H,
J=7.5 Hz), 1.98 (d, 3H, J=1.5 Hz), 2.86 (q, 2H,
J=7.5 Hz), 5.08 (s, 1H), 6.88 (d, 1H, J=7.8, Hz),
6.97 ((apparent)t, 1H, J=6.6 Hz), 7.25 (m, 2H), 7.63 (s,
1H).
3-(2-Hydroxy-phenyl)-propenal (2aj). A mixture of 2.5 g
(11.4 mmol) of 2-iodophenol, 1.41 mL (17.0 mmol) of
acrolein, 2.39
gencarbonate, 3.16
g
(28.4 mmol) of sodium hydro-
(11.4 mmol) of tetra-
g
butylammonium chloride hydrate and 26 mg (0.11
mmol) of palladium(II) acetate in 45 mL of DMF was
heated at 60 ꢀC for 16 h. After cooling to room tem-
perature the mixture was poured into water and extrac-
ted with ethyl acetate. The organic layers was separated
and then dried (sodium sulfate). The solvent was
removed witha rotary evaporator. Teh residue was
purified by MPLC (15–20% ethyl acetate in hexanes as
eluant) to afford 0.66 g (31%) of the title compound as a
1
4-(2-Hydroxy-3-methyl-phenyl)-but-3-en-2-one (2o). H
NMR (DMSO-d6) d 2.20 (s, 3H), 2.33 (s, 3H), 6.70-6.85
(m, 2H), 7.15 (d, 1H, J=6.0 Hz), 7.48 (d, 1H, J=6.0
Hz), 7.92 (distorted d, 1H, J=16.0 Hz).
1
4-(3,5-Di-tert-butyl-2-hydroxy-phenyl)-but-3-en-2-one
1
yellow solid. H NMR (CDCl3) d 6.88 (dd, 1H, J=8.1,
(2p). H NMR (DMSO-d6) d 1.27 (s, 9H), 1.38 (s, 9H),
1.2 Hz), 6.98 (d(apparent)t, 1H, J=7.5, 1.2 Hz), 7.00
(dd, 1H, J=15.9, 7.8 Hz), 7.31 (d(apparent)t, 1H,
J=7.8, 1.8 Hz), 7.51 (dd, 1H, J=7.5, 1.8 Hz), 9.68 (d,
1H, J=7.8 Hz).
2.35 (s, 3H), 6.65 (d, 1H, J=16.5, Hz), 7.29 (d, 1H,
J=2.2, Hz), 7.43 (d, 1H, J=2.2, Hz), 7.97 (d, 1H,
J=16.5, Hz), 9.07 (s, 1H); IR (KBr pellet) 3327, 2962,
1628, 1271, 1224, 978 cmÀ1. Anal. calcd for C18H26O2:
C, 78.79; H, 9.55. Found: C, 78.49; H, 9.46.
Compounds 2ak, 2al, 2an, and 2aq were prepared by a
similar procedure.
1
4-(4-Chloro-2-hydroxy-phenyl)-but-3-en-2-one (2s). H
NMR (DMSO-d6) d 2.30 (s, 3H), 6.81–6.96 (m, 3H),
7.60–7.75 (m, 2H), 10.75 (s, 1H).
3-(2-Hydroxy-benzylidene)-pentan-2-one (2ak). Prepared
using 3-methylene pentan-2-one: 1H NMR (CDCl3)
d 1.06 (t, 3H, J=7.5 Hz), 2.46 (q, 2H, J=7.5 Hz),
2.47 (s, 3H), 5.26 (s, 1H), 6.88 (d, 1H, J=8.4 Hz),
6.97 ((apparent)t, 1H, J=7.5 Hz), 7.26 (m, 2H), 7.59 (s,
1H).
1
4-(2-Hydroxy-5-methyl-phenyl)-but-3-en-2-one (2t). H
NMR (DMSO-d6) d 2.21 (s, 3H), 2.29 (s, 3H), 6.80 (d,
1H, J=16.5, Hz), 6.81 (d, 1H, J=8.4, Hz), 7.05 (dd,
1H, J=8.4, 2.0 Hz), 7.41 (s, 1H), 7.74 (d, 1H, J=16.5
Hz), 9.98 (s, 1H). Anal. calcd for C11H12O2: C, 74.98;
H, 6.86. Found: C, 75.04; H, 6.95.
3-(2-Hydroxy-phenyl)-2-methyl-propenal (2al). Prepared
1
using methacrolein: H NMR (CDCl3) d 2.04 (d, 3H,
J=1.5 Hz), 6.91 (d, 1H, J=8.1 Hz), 6.99 ((apparent)t,
1H, J=8.1 Hz), 7.28 (d(apparent)t, 1H, J=7.8, 1.5 Hz),
7.45 (dd, 1H, J=7.8, 1.5 Hz), 7.64 (s, 3H).
1
4-(3-Fluoro-2-hydroxy-phenyl)-but-3-en-2-one (2v). H
NMR (DMSO-d6) d 2.32 (s, 3H), 6.75–6.90 (m, 2H),
7.24 (br t, 1H, J=9.6 Hz), 7.46 (d, 1H, J=7.8 Hz), 7.79
(d, 1H, J=16.5 Hz), 10.4 (s, 1H). Anal. calcd for
C10H9FO2: C, 66.67; H, 5.03. Found C, 66.41; H, 5.02.
2 - (2 - Hydroxy - benzylidene) - butyraldehyde (2an). Pre-
pared using 2-methylene butyraldehyde: 1H NMR
(CDCl3) d 1.12 (t, 3H, J=7.5 Hz), 2.50 (q, 2H, J=7.5
Hz), 5.14, (s, 1H), 6.86 (d, 1H, J=7.5 Hz), 7.00
((apparent)t, 1H, J=7.5 Hz), 7.28 ((apparent)t, 1H,
J=8.4 Hz), 7.41 (d, 1H, J=8.4 Hz), 7.50 (s, 1H), 9.60
(s, 1H).
4-(2-Hydroxy-3,4-dimethoxy-phenyl)-but-3-en-2-one
1
(2x). H NMR (DMSO-d6) d 2.27 (s, 3H), 3.69 (s, 3H),
3.83 (s, 3H), 6.60 (d, 1H, J=8.7 Hz), 6.74 (d, 1H,
J=16.2 Hz), 7.36 (d, 1H, J=8.7 Hz), 7.70 (d, 1H,
J=16.2 Hz), 9.65 (s, 1H).
4-(2-Hydroxy-phenyl)-3-methyl-but-3-en-2-one (2aq).
Prepared using 3-methylene butan-2-one: 1H NMR
(CDCl3) d 1.97 (s, 3H), 2.48 (s, 3H), 4.92 (s, 1H), 6.83
(d, 1H, J=5.1 Hz), 6.98 ((apparent)t, 1H, J=4.5 Hz),
7.29 (m, 2H), 7.63 (brs, 1H).
4-(2-Hydroxy-6-methoxy-phenyl)-but-3-en-2-one (2aa).
1H NMR (DMSO-d6) d 2.26 (s, 3H), 3.83 (s, 3H), 6.54
((apparent) t, 2H, J=8.4 Hz), 7.11 (d, 1H, J=16.5 Hz),
7.18 (t, 1H, J=8.4 Hz), 7.86 (d, 1H, J=16.5 Hz), 10.35

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
607
Procedure B: preparation of compounds 1. The prepara-
tion of 9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7
9-Methyl-4-trifluoromethoxy-8-oxa-10,12-diaza-tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1m). H NMR (DMSO-d6) d 1.69 (s, 3H), 2.18 (dis-
]
1
trideca-2,4,6-trien-11-ylidene cyanamide (1a) has been
previously described8 and is representative. Piperidine
(2.5 mL) was added to a mixture of 2a (12.4 g, 76.3
mmol), cyanamide (9.6 g, 229 mmol), and 1,2-dime-
thoxyethane (150 mL) at room temperature. The result-
ing bright orange mixture was heated at reflux for 6 h,
cooled to room temperature, and filtered. The solid
product was washed with 1,2 dimethoxyethane and
torted d, 2H), 4.55 (br s, 1H), 6.93 (d, 1H, J=8.7 Hz),
7.15–7.25 (overlapping s and d, 2H total), 8.65 (br s,
1H), 8.79 (s, 1H); IR (KBr pellet) 3187, 2183, 1639,
1250 cmÀ1
.
9-Ethyl-13-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
1
trideca-2,4,6-trien-11-ylidene-cyanamide (1n). H NMR
1
dried to give 8.16 g of 1a as a white solid. H NMR
(DMSO-d6) d 0.97 (m, 6H), 1.73 (dt, 1H, J=7.5, 7.2
Hz), 2.02 (dt, 1H, J=7.5, 7.2 Hz), 2.28 (d, 1H, J=6.3
Hz), 4.21 (br s, 1H), 6.83 (d, 1H, J=8.1 Hz), 6.92
((apparent)t, 1H, J=7.5 Hz), 7.20 (m, 2H), 8.45 (br s,
1H), 8.58 (br s, 1H).
(DMSO-d6) d 1.68 (s, 3H), 2.15 (br d, 2H, J=3.0 Hz),
4.47–4.52 (m, 1H), 6.81 (d, 1H, J=7.2 Hz), 6.92 (t, 1H,
J=7.2 Hz).
The following compounds were prepared by use of
Procedure B using the appropriate substrates 2.
6,9-Dimethyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca
- 2,4,6 - trien - 11 - ylidene - cyanamide (1o). 1H NMR
(DMSO-d6) d 1.70 (s, 3H), 2.10 (s, 3H), 2.13 ((appa-
rent)d, 2H), 4.47 (br s, 1H), 6.82 (t, 1H, J=7.5 Hz), 7.07
((apparent)d, 2H), 8.63 (br s, 2H). Anal. calcd for
C13H14N4O: C, 64.45; H, 5.82; N, 23.12. Found: C,
63.92; H, 5.80; N, 22.94.
4-Chloro-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
1
trideca-2,4,6-trien-11-ylidene-cyanamide (1b). H NMR
(DMSO-d6) d 1.68 (s, 3H), 2.16 (m, 2H), 4.52 (br d, 1H),
6.86 (d, 1H, J=8.7 Hz), 7.20–7.35 (m, 2H), 8.63 (br s,
1H), 8.76 (s, 1H); IR (KBr pellet) 3195, 2190, 1650,
1551, 1473, 1173, 712 cmÀ1
.
Anal. calcd for
C12H11ClN4O: C, 54.87; H, 4.22; N, 21.33. Found: C,
54.62; H, 4.14; N, 21.26.
4,6-Di-tert-butyl-9-methyl-8-oxa-10,12-diaza-tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1p). H NMR (DMSO-d6) d 1.26 (s, 9H), 1.33 (s, 9H),
1
4,6 - Dichloro - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1c). 1H NMR (DMSO-d6) d 1.74 (s, 3H), 2.22 (m,
2H), 4.60 (m, 1H), 7.28 (d, 1H, J=2.4 Hz), 7.54 (d, 1H,
J=2.4 Hz), 8.72 (s, 1H), 8.90 (s, 1H). Anal. calcd for
C12H10Cl2N4O: C, 48.51; H, 3.39; N, 18.85. Found: C,
47.73; H, 3.25; N, 18.56.
1.72 (s, 3H), 2.10 (m, 2H), 4.44 (m, 1H), 7.12 (d, 1H,
J=2.4 Hz), 7.16 (d, 1H, J=2.4 Hz), 8.59 (br d, 1H),
8.71 (s, 1H); IR (KBr pellet) 3222, 2954, 2175, 1630,
1162 cmÀ1. Anal. calcd for C20H28N4O: C, 70.56; H,
8.29; N, 14.46. Found: C, 68.94; H, 8.40; N, 15.28.
5-Chloro-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
1
trideca-2,4,6-trien-11-ylidene-cyanamide (1s). H NMR
4,6 - Dibromo - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1d). 1H NMR (DMSO-d6) d 1.73 (s, 3H), 2.21 (m,
2H), 4.58 (distorted q, 1H), 7.43 (d, 1H, J=2.1 Hz),
7.74 (d, 1H, J=2.1 Hz), 8.70 (br s, 1H), 8.91 (s, 1H).
Anal. calcd for C12H10Br2N4O: C, 37.34; H, 2.61; N,
14.51. Found: C, 37.31; H, 2.49; N, 14.38.
(DMSO-d6) d 1.68 (s, 3H), 2.16 (m, 2H), 4.52 (br s, 1H),
6.92 (d, 1H, J=2.1 Hz), 7.00 (dd, 1H, J=8.1, 2.1 Hz),
7.26 (d, 1H, J=8.1 Hz), 8.70 (br s, 1H), 8.78 (s, 1H).
4,9-Dimethyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca
- 2,4,6 - trien - 11 - ylidene - cyanamide (1t). 1H NMR
(DMSO-d6) d 1.66 (s, 3H), 2.11 ((apparent)d, 2H), 2.23
(s, 3H), 4.42 (m, 1H), 6.71 (d, 1H, J=7.8 Hz), 6.98–7.05
(m, 2H), 8.61 (br s, 2H).
9-Methyl-4-nitro-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]tri-
1
deca-2,4,6,11-tetraen-11-yl-cyanamide (1e). H NMR
(DMSO-d6) d 1.74 (s, 3H), 2.25 (m, 2H), 4.70 (m, 1H),
7.05 (d, 1H, J=9.0 Hz), 8.10 (dd, 1H, J=9.0, 2.4 Hz),
8.24 (d, 1H, J=2.4 Hz), 8.75 (br s, 1H), 8.96 (s, 1H).
6-Fluoro-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca - 2,4,6 - trien - 11 - ylidene - cyanamide (1v). Com-
pound 1v was purified by silica gel chromatography
using a gradient of 5–25% EtOH in dichloromethane as
the eluant. 1H NMR (DMSO-d6) d 1.72 (s, 3H), 2.21 (m,
2H), 4.56 (br s, 1H), 6.88–6.98 (m, 1H), 7.05–7.20 (m,
2H), 8.74 (d, 1H), 8.79 (s, 1H).
9 - Ethyl - 8 - oxa - 10,12 - diaza - tricyclo[7.3.1.02,7]trideca -
2,4,6,11 - tetraen - 11 - yl - cyanamide (1h). 1H NMR
(DMSO-d6) d 0.95 (t, 3H, J=7.5 Hz), 1.99 (m, 2H,),
2.08 (d, 2H, J=3.0 Hz), 4.51 (br s, 1H), 6.82 (d, 1H,
J=7.5 Hz), 6.89 ((apparent)t, 1H, J=7.5 Hz). 7.24 (m,
2H), 8.55 (br s, 1H), 8.66 (br s, 1H); IR (KBr): 3216,
5,6 - Dimethoxy - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca- 2,4,6,11- tetraen-11- yl - cyanamide
(1x). 1H NMR (DMSO-d6) d 1.70 (s, 3H), 2.12 (m,
2H), 3.63 (s, 3H), 3.75 (s, 3H), 4.42 (m, 1H), 6.63 (d, 1H,
J=8.4 Hz), 6.92 (d, 1H, J=8.4 Hz), 8.62 (m, 1H), 8.73
(s, 1H).
2184, 1618 cmÀ1
.
9-Phenyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca-
2,4,6,11 - tetraen- 11-yl -cyanamide (1j). Prepared from
commercially available 2-hydroxychalcone using Proce-
dure B: 1H NMR (DMSO-d6) d 2.32 (m, 2H), 4.56 (br s,
1H), 7.01 (m, 2H), 7.31 (m, 2H), 7.46 (m, 3H), 7.65 (d,
2H, J=8.4 Hz), 8.57 (br s, 1H), 9.00 (br s, 1H).
3 - Methoxy - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
1
(1aa). H NMR (DMSO-d6) d 1.68 (s, 3H), 2.04 (m,

608
B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
2H), 3.82 (s, 3H), 4.74 (br s, 1H), 6.43 (d, 1H, J=8.2),
6.57 (d, 1H, J=8.2 Hz), 7.17 (t, 1H J=8.2 Hz), 8.55 (s,
1H), 8.66 (br s, 1H).
rent)t, 1H J=7.5 Hz), 7.24 (m, 2H), 8.60 (br s, 1H) 8.71
(br s, 1H).
12-Acetyl-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca-2,4,6-trien-11-ylidene-cyanamide (1f). Sodium
hydride (60% in oil, 74 mg, 1.8 mmol) was added to a
solution of 1a (420 mg, 1.8 mmol) and DMF (11 mL)
withstirring at 0–5 ꢀC (CAUTION: hydrogen evolu-
tion). The resulting mixture was stirred at 0 ꢀC for 1 h
and was then treated with acetic anhydride (0.26 mL,
2.8 mmol). The resulting mixture was stirred at room
temperature for 14 hand was then cooled to 0 ꢀC and
quenched with excess acetic acid (0.5 mL). The resulting
mixture was diluted withwater, causing the formation
of a white precipitate. The solid was isolated by filtra-
tion, washed with water, suspended in acetonitrile and
concentrated on the rotovap to give 360 mg (73%) of 1f
3,5 - Dichloro - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
1
(1ab). H NMR (DMSO-d6) d 1.71 (s, 3H), 2.17 (m,
2H), 4.79 (br s, 1H), 6.99 (d, 1H, J=2.1 Hz), 7.21 (d,
1H, J=2.1 Hz), 8.80 (s, 1H), 9.01 (br s, 1H). Anal. calcd
for C12H10Cl2N4O: C, 48.51; H, 3.39; N, 18.85. Found:
C, 48.10; H, 3.30; N, 18.70.
5-Fluoro-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
1
trideca-2,4,6-trien-11-ylidene-cyanamide (1ac). H NMR
(DMSO-d6) d 1.68 (s, 3H), 2.15 (m, 2H), 4.52 (m 1H),
6.70 (dd, 1H, J=8.0, 1.5 Hz), 6.78 (dt, 1H, J=8.0, 1.5
Hz), 7.27 ((apparent)t, 1H, J=8.0 Hz), 8.67 (m, 1H),
8.75 (s, 1H).
1
as a white solid. H NMR (DMSO-d6) d 1.80 (s, 3H),
2.22 (dd, 1H, J=13.8, 3.3 Hz), 2.38 (dd, 1H, J=13.8,
2.7 Hz), 2.48 (s, 3H), 5.78 (distorted s, 1H), 6.87 (d, 1H,
J=8.1 Hz), 6.96 (t, 1H, J=7.5 Hz), 7.2–7.3 (m, 2H),
9.35 (s, 1H); IR (KBr pellet) 2185, 1707, 1621, 1470,
1235, 754 cmÀ1. Anal. calcd for C14H14N4O2: C, 62.21;
H, 5.22; N, 20.73. Found: C, 61.18; H, 5.35; N, 19.47.
1H NMR NOE experiments showed NOE enhancement
between signals at d 1.80 and 9.35, indicating proximity
between the C9 methyl substituent and the N10 proton.
Therefore, acylation occurred preferrentially at the N12
nitrogen.
8-Oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca-2,4,6-trien-
11-ylidene-cyanamide (1aj). H NMR (CDCl3) d 2.22
(d(apparent)t, 1H, J=13.2, 2.7 Hz), 2.35 (d(apparent)t,
1H. J=13.2, 2.7 Hz), 4.55 (br s, 1H), 4.63 (brs, 1H),
6.76 (br, 1H), 6.90 (d, 1H, J=8.4 Hz), 6.96 ((apparent)t,
1H, J=7.2 Hz), 7.22 (m, 2H), 7.39 (br s, 1H).
1
13-Ethyl-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca - 2,4,6 - trien - 11 - ylidene - cyanamide (1ak). 1H
NMR (DMSO-d6) d 0.99 (t, 3H, J=7.2 Hz), 1.59 (s,
3H), 2.02 (m, 2H), 4.37 (br s, 1H), 6.80 (d, 1H, J=7.8
Hz). 6.92 ((apparent)t, 1H, J=7.5 Hz), 7.22 (m, 2H),
8.52 (br s, 1H), 8.57 (br s, 1H).
9,12-Dimethyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]tri-
deca - 2,4,6 - trien - 11 - ylidene - cyanamide (1g). Sodium
hydride (60% in mineral oil, 74 mg, 1.8 mmol) was
added to a solution of 1a (420 mg, 1.8 mmol) and DMF
(11 mL) at 0 ꢀC. After 1 h, iodomethane (0.34 mL, 5.5
mmol) was added at <10 ꢀC (slightly exothermic). The
resulting mixture was stirred at room temperature for 2
days and was then quenched by carefully adding water
(30 mL). The resulting solid product was isolated by
filtration, washed with water, and dried in vacuo to give
1g as a white solid (180 mg, 40% yield). 1H NMR
(DMSO-d6) d 1.76 (s, 3H, C–CH3), 2.19 (dd, 1H,
J=13.3, 2.7 Hz), 2.30 (dd, 1H, J=13.4, 2.9 Hz), 3.00 (s,
3H, N–CH3), 4.56 (distorted s, 1H, angular C–H), 6.86
(d, 1H, J=8.2 Hz), 6.93 (t, 1H, J=7.5 Hz), 7.25 (t, 1H,
J=7.5 Hz), 7.34 (d, 1H, J=7.6 Hz), 8.40 (s, 1H, N–H).
1H NMR NOE experiments showed NOE enhancement
between signals at d 3.00 and 4.56 (indicating proximity
between the N12 methyl and the C1 methine proton)
and enhancement between signals at d 1.76 and 8.40
(indicating proximity between the C9 methyl and the
N10 proton). Thus, methylation occurred preferentially
at the N12 nitrogen.
13-Methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca-
2,4,6 - trien - 11 - ylidene - cyanamide (1al). 1H NMR
(CDCl3) d 1.18 (d, 3H, J=6.9 Hz), [1.06 (d, 3H, J=6.9
Hz)], 2.47 (m, 1H), [2.40 (m, 1H)], 4.23 (m, 1H), [4.19
(m, 1H)], 5.23 (m, 1H), [5.26 (m, 1H)], 6.67 (br s, 1H),
6.89 (d, 1H, J=7.8 Hz), 6.95 ((apparent)t, 1H J=7.5
Hz), 7.22 (m, 2H), 7.33 (br s, 1H).
13-Ethyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]trideca-
2,4,6 - trien - 11 - ylidene - cyanamide (1an). 1H NMR
(CDCl3) d 1.06 (t, 3H, J=7.5 Hz), 2.20 (dt, 1H, J=7.5,
6.1 Hz), 4.35 (m, 1H), 5.31 (m, 1H), 6.75 (br s, 1H), 6.89
(d, 1H, J=8.1 Hz), 6.95 ((apparent)t, 1H J=7.5 Hz),
7.24 (m, 2H), 7.42 (br s, 1H).
Reaction of 2aq withcyanamide and piperidine as
described for 1a gave a mixture of endo- and exo- iso-
mers that were separated by silica gel chromatography.
The faster eluting isomer was the endo-compound: rel-
(1R,9R,13S) - 9,13 - dimethyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
1
(1ar). H NMR (DMSO-d6) d 1.02, (d, 3H, J=6.6 Hz),
12-Methanesulfonyl-9-methyl-8-oxa-10,12-diaza-tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1i). Sodium hydride (60% in oil, 73 mg, 1.8 mmol)
was added to a solution of 1a (414 mg, 1.8 mmol) and
DMF (11 mL) withice-water bathcooling (CAUTION:
hydrogen evolution). After stirring at 5 ꢀC for 30 min,
methane sulfonic anhydride (347 mg, 2.0 mmol) was
added (slightly exothermic to 10 ꢀC). The resulting yel-
low solution was stirred at room temperature for 16 h
1.58 (s, 3H), 2.24 (m, 1H) 4.20 (m, 1H), 6.80 (d, 1H,
J=8.7 Hz), 6.91 ((apparent)t, 1H J=7.5 Hz), 7.20 (m,
2H), 8.56 (br s, 2H). Further elution gave the exo-
isomer: rel-(1R,9R,13R)-9,13-dimethyl-8-oxa-10,12-diaza-
tricyclo[7.3.1.02,7]trideca-2,4,6-trien-11-ylidene-cyanamide
1
(1aq). H NMR (DMSO-d6) d 0.84, (d, 3H, J=6.9 Hz),
1.58 (s, 3H), 2.18 (dq, 1H, J=6.9, 2.7 Hz) 4.18 (dd, 1H,
J=4.5, 2.7 Hz), 6.81 (d, 1H, J=8.1 Hz), 6.95 ((appa-

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
609
and was then cooled to 5 ꢀC and treated withan addi-
tional portion of methane sulfonic anhydride (150 mg).
After stirring an additional 16 hat room temperature,
the reaction was diluted with water (30 mL) and the
resulting green suspension was filtered. The tan solid
product was washed with water and triturated with
tate in hexanes as eluant, 1q was isolated in 6% yield as
a solid. Rf (silica gel TLC, 50% EtOAc in hex-
anes)=0.47; H NMR (DMSO-d6) d 1.80 (s, 3H), 2.25
(dd, 1H, J=14.1, 3.2 Hz), 2.39 (dd, 1H, J=13.7, 2.6
Hz), 2.48 (s, 3H), 5.76 (t, 1H, J=2.9 Hz), 6.77–6.85 (m,
2H), 7.34 (t, 1H, J=7.7 Hz), 9.42 (s, 1H).
1
1
hexanes to give 75 mg (13%) of 1i as a tan solid. H
NMR (DMSO-d6) d 1.81 (s, 3H), 2.37 (dd, 1H, J=13.6,
2.9 Hz), 2.42 (dd, 1H, J=13.5, 2.9 Hz), 3.32 (s, 3H),
3.47 (s, 3H), 5.62 ((apparent)t, 1H), 6.92 (d, 1H, J=8.1
Hz), 7.02 (t, 1H, J=7.5 Hz), 7.28–7.35 (m, 2H), 9.62 (s,
1H).
12-Benzyl-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca - 2,4,6 - trien - 11 - ylidene - cyanamide (1r). Com-
pound 1r was prepared in 80% yield using a procedure
analogous to that described for the preparation of 1g
(using benzyl bromide in place of iodomethane). 1H
NMR (DMSO-d6) d 1.80 (s, 3H), 2.20 (d, 1H, J=13.6
Hz), 2.27 (dd, 1H, J=13.7, 2.9 Hz), 4.45 (d, 1H, J=15.5
Hz), 4.53 (m, 1H), 4.94 (d, 1H), 6.86 ((apparent)d, 2H,
J=7.7 Hz), 7.1–7.4 (m, >7H), 8.59 (s, 1H).
11 - Cyanoimino - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - triene - 12 - carboxylic acid
methyl ester (1k). Sodium hydride (60% in mineral oil,
70 mg, 1.8 mmol) was added to a solution of 1a (400
mg, 1.8 mmol) and DMF (11 mL) at 5 ꢀC (CAUTION:
hydrogen evolution). The resulting nearly homogeneous
mixture was stirred at 5 ꢀC for 30 min and was then
treated withdimetyhl pyrocarbonate (0.21 mL, 1.9
mmol). The resulting solution was stirred at room tem-
perature for 14 hand was then quenched by carefully
adding water (30 mL). The solid product was collected
by filtration and was purified by chromatography on
silica gel using 20% EtOAc in hexanes as the eluant to
give 48 mg (12%) of 1k as a white solid. 1H NMR
(DMSO-d6) d 1.74 (s, 3H), 2.25 (dd, 1H, J=13.9, 3.4
Hz), 2.42 (dd, 1H, J=14.0, 2.7 Hz), 3.86 (s, 3H), 5.45
((apparent)t, 1H, J=2.9 Hz), 6.88 (d, 1H, J=7.9 Hz),
7.02 (t, 1H, J=7.6 Hz), 7.31 (t, 1H, J=7.6 Hz), 7.38
(dd, 1H, J=7.6, 1.4 Hz), 9.42 (s, 1H).
12-Ethyl-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca - 2,4,6 - trien - 11 - ylidene - cyanamide (1u). Com-
pound 1u was prepared in 16% yield (after trituration
withacetonitrile) using a procedure analogous to that
described for the preparation of 1g (using iodoethane
1
instead of iodomethane). H NMR (DMSO-d6) d 1.13
(t, 3H, J=7.0 Hz), 1.76 (s, 3H), 2.20 (m 2H), 3.25–3.40
(m, 1H, overlaps H2O signal), 3.62–3.72 (m, 1H), 4.67
(s, 1H), 6.85 (d, 1H, J=8.1 Hz), 6.92 (t, 1H, J=7.4 Hz),
7.24 (t, 1H, J=7.4 Hz), 7.40 (d, 1H, J=7.4 Hz), 8.37 (s,
1H).
9-Methyl-12-pyridin-2-ylmethyl-8-oxa-10,12-diaza-tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1w). Sodium hydride (154 mg of a 60% suspension in
mineral, 3.85 mmol) was added to a solution of 1a (400
mg, 1.75 mmol), 2-picolyl chloride hydrochloride salt
(316 mg, 1.9 mmol) and DMF (11 mL) at 0 ꢀC (slightly
exothermic). The resulting suspension was stirred at
room temperature for 2 days and was then cooled to
0 ꢀC and quenched by carefully adding water (30 mL).
The solid product was isolated by filtration, dried on the
frit, washed with hexanes and dried again to give 1w as
a light pink solid (420 mg, 75% yield). 1H NMR
(DMSO-d6) d 1.81 (s, 3H), 2.22 (br d, 1H, J=4.8 Hz),
2.44 (dd, 1H, J=13.4, 3.2 Hz), 4.61 (d, 1H, J=16.2 Hz),
4.67 (m, 1H), 4.98 (d, 1H, J=16.2 Hz), 6.82–6.90 (m,
2H), 7.20–7.35 (m, 4H), 7.78 (dt, 1H, J=7.6, 1.9 Hz),
8.57 (d, 1H, J=4.8 Hz), 8.61 (s, 1H).
9,10,12-Trimethyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca-2,4,6-trien-11-ylidene cyanamide (1l). Sodium
hydride (180 mg, 4.4 mmol) was added to a solution of
1a (400 mg, 1.8 mmol) and DMF (11 mL) at 5 ꢀC
(CAUTION: hydrogen evolution). After stirring for 30
min at 5 ꢀC, iodomethane (0.55 mL, 8.8 mmol) was
added. The resulting thick yellow suspension was stirred
at room temperature for 14 hand was then treated with
an additional portion of iodomethane (0.11 mL) at 5 ꢀC.
After stirring 14 hat room temperature, the mixture
was cooled to 5 ꢀC and was then carefully quenched by
the addition of water (50 mL). The crude product was
isolated by filtration and was then purified by silica gel
chromatography using a gradient of 25–33% EtOAc in
hexanes as the solvent. After initial elution of 1g (Rf
0.79, silica gel TLC, 100% EtOAc), 1l was obtained as a
white solid (67 mg, 15%). Rf (silica gel TLC, 100%
EtOAc)=0.47; 1H NMR (DMSO-d6) d 1.73 (s, 3H),
2.24 (dd, 1H, J=13.5, 3.1 Hz), 2.42 (dd, 1H, J=13.7,
2.5 Hz), 3.00 (s, 3H), 3.26 (s, 3H), 4.54 ((apparent)t, 1H,
J=2.9 Hz), 6.88 (d, 1H, J=8.0 Hz), 6.99 (t, 1H, J=7.5
Hz), 7.27 (t, 1H, J=7.8 Hz), 7.40 (dd, 1H, J=7.6, 1.4
Hz).
12-Allyl-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca - 2,4,6 - trien - 11 - ylidene - cyanamide (1y). Com-
pound 1y was prepared in 38% yield using a procedure
analogous to that described for the preparation of 1g
(using allyl bromide in place of iodomethane): 1H NMR
(DMSO-d6) d 1.78 (s, 3H), 2.20 (dd, 1H, J=13.4, 2.4
Hz), 2.28 (dd, 1H, J=13.4, 2.9 Hz), 3.85 (dd, 1H,
J=16.1, 6.2 Hz), 4.35 (dd, 1H, J=15.9, 4.9 Hz), 4.54 (s,
1H), 5.21 (d, 1H, J=10.3 Hz), 5.30 (s, 1H), 5.73–5.85
(m, 1H), 6.84 (d, 1H, J=8.0 Hz), 6.92 (t, 1H, J=7.5
Hz), 7.24 (t, 1H, J=7.8 Hz), 7.35 (d, 1H, J=7.6 Hz),
8.50 (s, 1H).
12-Acetyl-5-fluoro-9-methyl-8-oxa-10,12-diaza-tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1q). Compound 1q was prepared using a method ana-
logous to that described for the preparation of com-
pound 1f (using 1ac in place of 1a). After silica gel
chromatography using a gradient of 20–60% ethyl ace-
9-Methyl-12-trimethylsilanylmethyl-8-oxa-10,12-diaza-
tricyclo[7.3.1.02,7]trideca-2,4,6-trien-11-ylidene-cyana-
mide (1z). Compound 1z was prepared in 14% yield

610
B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
using a procedure analogous to that described for the
preparation of 1g (using iodomethyl trimethylsilane in
place of iodomethane): H NMR (DMSO-d6) d 0.04 (s,
9H), 1.77 (s, 3H), 2.25 (m, 2H), 2.84 (d, 1H, J=15.0
Hz), 3.16 (d, 1H, J=15.0 Hz), 4.46 (m, 1H), 6.86 (d, 1H,
J=8.1 Hz), 6.92 (t, 1H), 7.25 (dt, 1H, J=7.6, 1.8 Hz),
7.44 (dd, 1H, J=7.7, 1.4 Hz), 8.28 (s, 1H).
1H, 14.1, 3.3), 2.36 (dd, 1H, J=14.1, 2.4 Hz), 3.67 (m,
1H), 5.59 (t, 1H, J=3.0 Hz), 6.89 (d, 1H, J=7.4 Hz),
6.97 (td, 1H, J=7.4, 1.5 Hz), 7.27 (td, 1H, J=6.9, 1.5
Hz), 7.38 (dd, 1H, J=6.9, 1.5 Hz), 9.38 (s, 1H).
1
4-Amino-9-methyl-8-oxa-10,12-diaza-tricyclo[7.3.1.02,7]-
trideca-2,4,6-trien-11-ylidene-cyanamide (1ai). 10% Pal-
ladium on carbon (56 mg) was added to a nitrogen-
degassed solution of 1e (56 mg, 0.20 mmol) and metha-
nol (11 mL). The resulting mixture was degassed under
hydrogen and stirred under 1 atmosphere of hydrogen
(balloon) for 1.5 h. The resulting mixture was degassed
under nitrogen and filtered through Celite. The filter
caked was washed with methanol and the combined fil-
trates were concentrated to give crude product. Silica
gel chromatography using 10% ethanol in methylene
chloride gave 1ai as a solid (29 mg, 55% yield). 1H
NMR (DMSO-d6) d 1.61 (s, 3H), 2.02 (m, 2H), 4.26 (m,
1H), 4.75 (br s, 2H), 6.4–6.5 (m, 3H), 8.43 (s, 1H), 8.60
(m, 1H).
(11 - Cyanoimino - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca-2,4,6-trien-12-yl)-acetic acid methyl
ester (1ad). Prepared in 13% yield using a procedure
analogous to that described for the preparation of 1g
(using methyl bromoacetate in place of iodomethane).
Pure product was isolated after trituration withoht
1
methanol. H NMR (DMSO-d6) d 1.80 (s, 3H), 2.24
(br d, 1H, J=13.7 Hz), 2.32 (dd, 1H, J=13.5, 3.0 Hz),
3.66 (s, 3H), 4.28 (d, 1H, J=17.7 Hz), 4.39 (d, 1H,
J=17.7 Hz), 4.71 (br t, 1H, J=2.6 Hz), 6.85 (d, 1H,
J=6.9 Hz), 6.91 (t, 1H, J=6.9 Hz), 7.22 ((apparent)t,
1H, J=7.8 Hz), 7.41 ((apparent)d, 1H, J=7.8 Hz), 8.72
(s, 1H).
9-Methyl-12-(2,2,2-trifluoro-acetyl)-8-oxa-10,12-diaza-
tricyclo[7.3.1.02,7]trideca-2(7),3,5-trien-11-ylidene-cyana-
mide (1am). To a nearly homogeneous solution of 1a
(300 mg, 1.3 mmol) and THF (15 mL) was added tri-
fluoroacetic anhydride (0.61 mL, 7.9 mmol) at room
temperature. After 6 h, the reaction mixture was heated
at reflux. After 1.5 hat reflux, the reaction mixture was
cooled to room temperature and concentrated. Silica gel
chromatography of the residue using 20% EtOAc in
hexanes as the eluant gave 1am as an oil (6 mg, 2%
yield). Rf (silica gel TLC, 50% EtOAc in hex-
9 - Methyl - 12 - prop - 2 - ynyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1ae). Prepared in 60% yield using a procedure analo-
gous to that described for the preparation of 1g (using
1
propargyl chloride in place of iodomethane). H NMR
(DMSO-d6) d 1.25 (br s, 1H), 1.77 (s, 3H), 2.25 (m, 2H),
4.16 (dd, 1H, J=17.7, 2.5 Hz), 4.47 (dd, 1H, J=17.7,
2.5 Hz), 4.77 (br t, 1H), 6.83 (d, 1H, J=7.4 Hz), 6.92 (t,
1H, J=6.6 Hz), 7.24 (t, 1H, J=6.6 Hz), 7.42 (d, 1H,
J=6.6 Hz), 8.67 (s, 1H).
1
anes)=0.76; H NMR (CDCl3) d 1.94 (s, 3H), 2.22 (dd,
9 - Methyl - 12 - propionyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1af). Prepared in 60% yield using a procedure analo-
gous to that described for the preparation of 1f (using
1H, J=13.8, 2.9 Hz), 2.52 (dt, 1H, J=13.9, 2.1 Hz),
6.15 (t, 1H, J=2.9 Hz), 6.74 (br s, 1H), 6.91 (d, 1H,
J=8.3 Hz), 6.99 (t, 1H, J=7.6 Hz), 7.31 (t, 1H, J=7.7
Hz), 7.61 (dd, 1H, J=7.6, 1.4 Hz); MS (CI) m/e 325
(M+1, 100%).
1
propionic anhydride in place of acetic anhydride). H
NMR (DMSO-d6) d 1.07 (t, 3H, J=6.9 Hz), 1.80 (s,
3H), 2.22 (dd, 1H, J=13.5, 3.6 Hz), 2.35 (dd, 1H,
J=13.5, 2.6 Hz), 2.70–2.85 (m, 1H), 2.95-3.08 (m, 1H),
5.77 (br t, 1H, J=3.0 Hz), 6.90 (d, 1H, J=7.5 Hz), 6.96
(t, 1H, J=7.5 Hz), 7.24 (br t, 1H, J=7.5 Hz), 7.31 (d,
1H, J=7.5 Hz), 9.31 (s, 1H).
5 - Fluoro - 9,12 - dimethyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1ao). Compound 1ao was prepared using a procedure
analogous to that described for the preparation of 1g
(using 1ac in place of 1a). After trituration of the crude
product withmethanol, 1ao was isolated as a white solid
in 10% yield. 1H NMR (CDCl3) d 1.81 (s, 3H), 2.25 (dt,
1H, J=12.9, 2.2 Hz), 2.33 (dd, 1H, J=13.2, 3.2 Hz),
3.09 (s, 3H), 4.29 (t, 1H, J=3.1 Hz), 6.18 (br s, 1H),
6.6–6.7 (m, 2H), 7.11 (dd, 1H, J=8.3, 6.0 Hz).
12 - Butyryl - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1ag). Prepared in 72% yield using a procedure analo-
gous to that described for the preparation of 1f (using n-
butyric anhydride in place of acetic anhydride). 1H
NMR (DMSO-d6) d 0.90 (t, 3H, J=7.2 Hz), 1.5–1.7 (m,
2H), 1.80 (s, 3H), 2.23 (dd, 1H, J=14.4, 3.0 Hz), 2.35
(dd, 1H, J=14.4, 2.4 Hz), 2.72–2.85 (m, 1H), 2.90–3.02
(m, 1H), 5.75 (br t, 1H, J=3.0 Hz), 6.88 (d, 1H, J=7.8
Hz), 6.96 (t, 1H, J=7.8 Hz), 7.22–7.37 (m, 2H), 9.34 (br
s, 1H).
11-Cyanoimino-5-fluoro-9-methyl-8-oxa-10,12-diaza-tri-
cyclo[7.3.1.02,7]trideca - 2,4,6 - triene - 12 - carboxylic acid
methyl ester (1ap). Compound 1ap was prepared using
a method that was analogous to that described for the
preparation of 1f (using dimethyl pyrocarbonate in
place of acetic anhydride and using 1ac in place of 1a).
After quenching the reaction with water, the resulting
mixture was extracted withethyl acetate (3 Â) and the
combined organics were washed with water, dried over
MgSO4, and concentrated. Silica gel chromatography of
the residue using 50% EtOAc in hexanes gave 1ap as a
12 - Isobutyryl - 9 - methyl - 8 - oxa - 10,12 - diaza - tricy-
clo[7.3.1.02,7]trideca - 2,4,6 - trien - 11 - ylidene - cyanamide
(1ah). Prepared in 21% yield using a procedure analo-
gous to that described for the preparation of 1f (using
1
1
isobutyric anhydride in place of acetic anhydride). H
NMR (DMSO-d6) d 1.11 (m, 6H), 1.81 (s, 3H), 2.24 (dd,
white solid. H NMR (DMSO-d6) d 1.74 (s, 3H), 2.26
(br d, 1H, J=14.1 Hz), 2.47 (dd, 1H, J=14.8, 3.0 Hz),

B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
611
3.86 (s, 3H), 5.45 (t, 1H, J=3.0 Hz), 6.90–6.78 (m, 2H),
7.42 (dd, 1H, J=8.5, 6.5 Hz), 9.51 (s, 1H).
1ax was prepared from 2-benzyl-2-methyl-succinic
acid17 following the same general Scheme. 1H NMR
(DMSO-d6) d 1.40 (s, 3H), 1.86 (d, 1H, J=12.6 Hz),
2.06 (d, 1H, J=12.6 Hz), 2.91 (s, 2H), 4.44 (br s 1H,),
7.21 (m, 4H), 7.60 (br s, 1H), 8.12 (brs, 1H).
1,2,5,6-Tetrahydro-4H-1,5-methano-benzo[e][1,3]diazocin
-3-ylidene-cyanamide (1as). 1.29 g (7.93 mmol) of cis
1,2,3,4-tetrahydro-naphthalene-1,3-diamine was dis-
solved in 70 mL of 2-propanol. 1.89 g (7.93 mmol) of
diphenyl cyanocarbonimidate was added and the mix-
ture was refluxed for 4 h. After cooling, 0.93 g (57%) of
rel-(1R,5S,6R)-6-Methyl -1,2,5,6-tetrahydro-4H-1,5-
methano - benzo[e][1,3]diazocin - 3 - ylidene - cyanamide
(1ay). Compound 1ay was prepared from 2-(1-phenyl-
ethyl)-succinic acid 1-ethyl ester, which was prepared
from 2-(1-phenyl-ethylidene)-succinic acid 1-ethyl
1
the product was filtered off as a white solid. H NMR
(DMSO-d6) d 1.95 (d, 1H, J=12.3 Hz), 2.04 (d, 1H,
J=12.3 Hz), 2.87 (d, 1H, J=17.4 Hz), 3.01 (dd, 1H,
J=12.3, 3.6 Hz), 3.94 (s, 1H), 4.39 (d, 1H, J=3.6 Hz),
7.20 (m, 4H), 7.83 (s, 1H), 8.16 (s, 1H); IR (KBr): 3257,
2161, 1630 cmÀ1. Anal. calcd for C12H12N4: C, 67.91;
H, 5.70; N, 26.40. Found: C, 67.82; H, 5.69; N, 26.54.
1
ester18 by hydrogenation. H NMR (DMSO-d6) d 1.17
(d, 3H, J=5.4 Hz), 1.83 (d(apparent)t, 1H, J=9.9, 2.4
Hz), 2.20 (d, 1H, J=9.9 Hz), 2.99 (q, 1H, J=5.4 Hz),
3.63 (m, 1H), 4.35 (m, 1H), 7.22 (m, 4H), 7.89 (br s,
1H), 8.15 (br s, 1H).
rel-(1R,5R,11R)-11-Methyl-1,2,5,6-tetrahydro-4H-1,5-
methano-benzo[e][1,3]diazocin-3-ylidene-cyanamide (1at)
and rel-(1R,5R,11S)-11-methyl-1,2,5,6-tetrahydro-4H-
1,5-methano-benzo[e][1,3]diazocin-3-ylidene-cyanamide
(1au). Compounds 1at and 1au were prepared starting
from 2-benzyl-3-methyl-succinic acid 1-methyl ester16 fol-
lowing the same general Scheme. The diastereomers were
separated at the lactam stage. 1at (endo-isomer): 1H
NMR (DMSO-d6) d 1.01 (d, 3H, J=5.1 Hz), 2.13 (m,
1H), 2.90 (dd, 1H, J=13.6, 0.9 Hz), 3.05 (dd, 1H,
J=13.6, 3.0 Hz), 3.56 (m, 1H), 4.08 (m, 1H), 7.22 (m,
rel-(1R,5R,11S)-5,11-Dimethyl-1,2,5,6-tetrahydro-4H-
1,5-methano-benzo[e][1,3]diazocin-3-ylidene-cyanamide
(1az). Compound 1az was prepared from 2-benzyl-2,3-
dimethyl-succinic acid which was obtained by hydro-
lysis of 2,3-dicyano-2,3-dimethyl-4-phenyl-butyric acid
ethyl ester.19 1H NMR (DMSO-d6) d 0.84 (d, 3H, J=7.2
Hz), 1.33 (s, 3H), 1.97 (q, 1H, J=7.2 Hz), 2.82 (s, 2H),
4.14 (m, 1H), 7.22 (m, 4H), 7.56 (br s, 1H), 8.16 (br s,
1H).
Compound 1az was isolated as predominantly a single
isomer. The stereochemistry at C-11 was assigned by
similarity of the shift of the methyl group to that of
compound 1au.
1
4H), 7.74 (s, 1H), 8.08 (m, 1H). 1au (exo-isomer): H
NMR (DMSO-d6) d 0.88 (d, 3H, J=6.9 Hz), 2.51 (m, 1H),
2.90 (d, 1H, J=18.0 Hz), 3.05 (dd, 1H, J=18.0, 4.2 Hz),
3.69 (m, 1H), 4.08 (m, 1H), 7.21 (m, 4H), 7.84 (s, 1H), 8.15
(m, 1H). The stereochemical assignments of 1at and 1au
were made by a NOE difference experiment. Irradiation
of the proton at C-11 (d 2.13) of 1at gave rise to
enhancement of the signal at d 3.05 (one of the benzylic
protons at C-6). Irradiation of the methyl group of 1au
gave rise to enhancement of the signal at d 3.05.
Biological Assays
Corn planthopper test
Test unit. The test unit consists of a plastic cup con-
taining 126Æ4 g of sterilized, non-fertilized sassafras
(sandy loam) soil. One pre-germinated Pioneer variety
3394 corn seed was placed in a 1 inchdepression in the
soil and covered. The test unit was watered with 15 mL
of distilled water and placed in a closed plexiglas box
inside a greenhouse operating 24 ꢀC and 36% relative
humidity for 4 days at which time it was ready for test.
A snug fitting test unit lid witha small opening at the
top was placed on all test units prior to test.
2 - Acetyl - 1,2,5,6 - tetrahydro - 4H - 1,5 - methano - ben-
zo[e][1,3]diazocin-3-ylidene-cyanamide (1av) and 4-Acetyl
-1,2,5,6-tetrahydro-4H-1,5-methano-benzo[e][1,3]diazocin
-3-ylidene-cyanamide and (1aw). To a solution of 0.10 g
(0.47 mmol) of compound 1as in 5 mL of DMF at 0 ꢀC
was added 19 mg (0.47 mmol) of sodium hydride (60%
dispersion in mineral oil). After 1 h0.070 mL (0.71
mmol) of acetic anhydride was added and the reaction
was stirred overnight at room temperature. The reaction
mixture was poured into water and extracted withethyl
acetate. The organic layer was separated and dried
(sodium sulfate). The solvent was removed with a rotary
evaporator. The residue was purified by MPLC (40–50%
ethyl acetate in hexanes as eluent). Eluting first was
compound 1aw (13 mg, 11% yield) and then compound
Compound application. Test compounds were for-
mulated at 250 ppm in 20% acetone/80% water con-
taining 500 ppm Ortho X-77 surfactant. For example,
2.5 mg of compound 1 was formulated in 10 mL solu-
tion. Compounds were applied through the opening in
the test unit lid with an atomizer sprayer fitted with a
Model 17690-1/8JJAU nozzle and a spray set-up con-
sisting of a J2850 Fluid Cap and J70 Air Cap (Spray
Sytems, Inc.). The sprayer was operated at 12–13psi.
For eachcompound, two test units were sprayed witha
total of 2 mL eachof test solution. After spraying, test
units were placed in a ventilated enclosure for 10–15
min to dry. 50 and 10 ppm solutions of 1 were prepared
by serial dilutions using 20% acetone: 80% water con-
taining 500 ppm Ortho X-77 surfactant.
1
1av (26 mg, 22% yield). 1av: H NMR (CDCl3) d 2.20
(m, 2H), 2.60 (s, 3H), 3.07 (m, 2H), 4.19 (m, 1H), 6.07
((apparent(t), 1H, J=3.0 Hz), 7.20 (m, 4H), 7.51 (d, 1H,
J=7.2 Hz). 1aw: 1H NMR (CDCl3) d 2.24 (m, 2H), 2.60
(s, 3H), 3.11 (m, 2H), 4.57 (m, 1H), 5.19 (m, 1H), 7.14
(d, 1H, J=7.5 Hz), 7.28 (m, 4H).
5 - Methyl - 1,2,5,6 - tetrahydro - 4H - 1,5 - methano - ben-
zo[e][1,3]diazocin-3-ylidene-cyanamide (1ax). Compound

612
B. L. Finkelstein et al. / Bioorg. Med. Chem. 10 (2002) 599–613
Insect infesting/evaluation. After drying, a thin layer of
white quartz sand wea poured onto the soil of each test
unit to aid in the evaluation of live and dead insects at
the conclusion of the test. Each unit was infested with a
minimum of 15 nymphs of the corn planthopper, Pere-
grinus maidis, which were approximately 21 days old.
Infested test units were held in a growth chamber oper-
ating at 22 ꢀC and 50% relative humidity with a 16:8
light/dark photoperiod. Insect mortality was evaluated
at 6 days post-infestation. Moribund insects were coun-
ted as dead. A compound 1 was considered ‘active’
when the observed insect mortality was 80% or greater.
partially-purified AChE extract was stored in 1.5 mL
aliquots at À80 ꢀC until ready for use. AChE extracts
for cornplanthopper (CPH) and green leafhopper
(GLH) were prepared similarly.
AChE inhibition assay. The procedure used was a varia-
tion of the colorimetric assay developed by Ellman et
al.20 The assay was run in 96-well plate format using a
Molecular Devices Thermo-max plate reader. Assay
components were as follows: 100 mM sodium phosphate,
pH 7.4 was used as buffer, 75 mM acetylthiocholine
iodine (ATC) in buffer was used as substrate, 10 mM 5,5-
dithio-bis(2-nitrobenzoic acid+17.8 mM sodium bicar-
bonate) (DTNB) in buffer was used as the colorimetric
reagent, 2-methoxy ethanol was used as solvent.
Green leafhopper soil/systemic test
Test unit. Rice seedlings were raised in a nursery box.
Five rice seedlings (1.5 leaf stage, about 10 cm tall) were
The assay was run in a final volume of 225 mL. To 185
mL of assay buffer in microplate wells was added 5 mL of
5 mM paraoxon in 2-methoxy ethanol or 5 mL of test
compound in 2-methoxy ethanol at concentrations ran-
ging from 1 nM to 100 mM final concentration in the
assay. The assay was initiated by addition of 20 mL of
partially-purified insect AChE (see above) and the mix-
ture was allowed to incubate for 30 min at room tem-
perature. After the first 25 min of incubation, a 1:1
mixture of ATC/DTNB was prepared. At 30 min, 15 mL
of this substrate plus colorimetric reagent mixture was
added to all wells and the microplate put in the plate
reader. The change in OD 405 nm was followed for 5
min (witha read interval of 9 s). Vmax (maximal dOD/
min) was determined using SoftMax Pro software
(Molecular Devices). % Inhibition was then calculated
versus solvent controls and IC50 values were calculated.
Triplicate determinations were made for eachcon-
centration of test compound.
1
transplanted into a oz. Plastic cup containing Kumiai
brown artificial soil.2
Compound application. Seven mL of a 100 ppm solution
of the test compound in 2.5:97.5 acetone/water (pre-
pared by dissolving, for example, 5 mg compound 1 in
1.25 mL acetone and then diluting the resulting solution
with48.75 mL water) was drenched onto the soil of each
test. There were four replications per test. After appli-
cation, the test units were covered and held in a growth
chamber at 27 ꢀC and 65% relative humidity for 24 h.
10 and 1.0 ppm solutions of 1 were prepared via serial
dilutions using 2.5:97.5 acetone/water.
Insect infesting/evaluation. After drying, the test units
were placed in conical shaped test units and the surface
of the soil was covered with 2–3 mm of quartz sand to
aid in the evaluation of live and dead insects at the
conclusion of the test. Approximately eight to ten green
leafhopper nymphs (Nephotettix cincticeps, 3rd–4th
instar) were infested into eachtest unit using an aspira-
tor. The test units were then held in a growth chamber
at 27 ꢀC and 65% relative humidity. Insect mortality
was evaluated at 6 days post-infestation. Insects that
cannot walk are classified as dead. A test compound 1
was considered to be ‘active’ when the observed insect
mortality was 80% or greater.
Acknowledgements
We gratefully acknowlege Professor Jan Svetlik of
Comenius University, Czech. Republic, for supplying us
withour initial sample of 1a. We would also like to
thank John Groce, Gina Blankenship and Jim Doughty
1
for assistance in obtaining H NMR and mass spectral
analyses.
Brown planthopper soil/systemic test. Test was carried
out in a manner identical to that described above for
green leafhopper except using brown planthopper
nymphs (Nilaparvata lugens).
References and Notes
1. For a review on acetylcholinesterase see: Quinn, D. M.
Chem. Rev. 1987, 87, 955.
AChE assays
2. For a leading reference in this area see: Jaen, J. C.; Moos,
W. H.; Johnson, G. Bioorg. Med. Chem. Lett. 1992, 2, 777.
3. Davis, K. L.; Powchik, P. Lancet 1995, 345, 625.
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moto, H.; Hopfinger, A. J. Bioorg. Med. Chem. 1996, 4, 1429.
5. For a review on galanthamine see: Sramek, J. J.; Frack-
iewicz, E. J.; Cutler, N. R. Expert Opin. Invest. Drugs 2000, 9,
2393.
Preparation of insect AChE extracts. Using a teflon/
glass tissue homogenizer, Southern corn rootworm
(SCRW, Diabrotica undecimpunctata) larvae were
homogenized in ice-cold 0.1 mM sodium phosphate
buffer (approx. 17 mL buffer/g SCRW). The homo-
genate was then centrifuged at 0 ꢀC for 10 min at 5000
rpm. An aliquot of the supernatant was tested in the
AChE assay (see below), omitting the inhibitor, and the
Vmax was determined. The remaining supernatant was
diluted withsufficient buffer to give a mixture having a
Vmax value of approx. 150 mOD/min. The resulting
6. For a review on rivastigmine see: Gottwald, M. D.;
Rozanski, R. I. Expert Opin. Invest. Drugs 1999, 8, 1673.
7. Han, Y.; Tang, X. In Alzheimer Disease: From Molecular
Biology to Therapy; Becker, R., Giacobini, E., Eds.; Birkhauser:
Boston, 1996: p 245.
¨

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8. (a) Svetlik, J.; Turecek, F.; Hanus, V. J. Chem. Soc., Perkin
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Trans 1 1988, 7 2053. (b) Svetlik, J. Czeck Patent 272723,
1991; (Chem. Abstr. 1992, 117, 212516. (c) McCann, S.F.;
Finkelstein, B.L. WO Patent 9946266, 1999: Chem. Abstr.
1999, 131, 214308.
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Organic Synthesis; Trost, B. M., Fleming, I., Eds; Pregamon:
Oxford, 1991; Vol. 4, p 833.
12. Shiotani, S.; Mitsuhashi, K. Chem. Pharm. Bull. 1966, 14, 324.
13. Huperzine A was tested for insecticidal activity. It
demonstrated 97% control of CPH at 50 PPM, but showed no
activity on BPH or GLH at 100 PPM. The reversible inhibi-
tors tacrine and galanthamine are active on SCRW at 1000
PPM, but not a lower rates.
14. The cyanoguanidine moiety in compounds 1 is also pre-
sent in insecticidal compounds suchas i shown below, which
acts as an agonist of the nicotinic acetylcholine receptor (see
e.g., Okazawa, A.; Akamatsu, M.; Nishiwaki, H.; Nakagawa,
Y.; Miyagawa, H.; Nishimura, K.; Ueno, T. Pest Manage. Sci.
2000, 56, 509). Compounds 1 were tested for agonist activity
at the nicotinic receptor and were shown to be inactive.
15. Raves, M. L.; Harel, M.; Pang, Y. P.; Silman, I.; Kozi-
kowski, A. P.; Sussman, J. L. Nat. Struct. Biol. 1997, 4, 57.
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17. Le Moal, H.; Foucard, A.; Hamelin, J.; Sevellec, C. Bull.
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18. Daub, G. H.; Johnson, W. S. J. Am. Chem. Soc. 1948, 70,
418.
19. Ogawa, Y.; Matsusaki, H.; Hanaoka, K.; Ohkata, K.;
Hanafusa, T. J. Org. Chem. 1978, 43, 849.
20. Ellman, G. L.; Courtney, K. D.; Andres, V.; Featherstone,
R. M. Biochem. Pharmacol. 1961, 7, 88.