Synthesis of 7,8-(methylenedioxy)-1-phenyl-3,5-dihydro-4H-2,3- benzodiazepin-4-ones as novel and potent noncompetitive AMPA receptor antagonists

Article abstract of DOI:10.1021/jm980168j

A group of 7,8-(methylenedioxy)-1-phenyl-3,5-dihydro-4H-2,3- benzodiazepin-4-ones was synthesized and assayed for antagonism of rat brain α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors expressed in Xenopus oocytes. The benzodiazepinones inhibited AMPA-activated membrane current responses in a manner consistent with noncompetitive, allosteric inhibition of the receptor-channel complex. The most potent compound in the series was 1-(4-aminophenyl)-7,8-(methylenedioxy)-3,5- dihydro-4H-2,3-benzodiazepin-4-one (6), which had an IC₅₀ of 2.7 μM. For comparison, the reference compound GYKI 52466 (2) had an IC₅₀ of 6.9 μM. Compound 6 also had potent anticonvulsant activity in a mouse maximum electroshock-induced seizure (MES) assay: the ED₅₀ was 2.8 mg/kg iv, whereas the ED₅₀ for GYKI 52466 was 4.6 mg/kg iv. In contrast to a previous report, the 7,8-dimethoxy analogue of 6 was a low-potency AMPA antagonist (IC₅₀ > 100 μM) and weak anticonvulsant (ED₆₀ > 10 mg/kg iv). The benzodiazepinones described herein are potent noncompetitive AMPA receptor antagonists that could have therapeutic potential as anticonvulsants and neuroprotectants.

Full text of DOI:10.1021/jm980168j

J . Med. Chem. 1998, 41, 2621-2625
2621
Syn th esis of 7,8-(Meth ylen ed ioxy)-1-p h en yl-3,5-d ih yd r o-4H-2,3-ben zod ia zep in -
4-on es a s Novel a n d P oten t Non com p etitive AMP A Recep tor An ta gon ists
Yan Wang, Christopher S. Konkoy, Victor I. Ilyin, Kimberly E. Vanover, Richard B. Carter, Eckard Weber,
J ohn F. W. Keana, Richard M. Woodward, and Sui Xiong Cai*
CoCensys, Inc., 201 Technology Drive, Irvine, California 92618
Received March 18, 1998
A group of 7,8-(methylenedioxy)-1-phenyl-3,5-dihydro-4H-2,3-benzodiazepin-4-ones was syn-
thesized and assayed for antagonism of rat brain R-amino-3-hydroxy-5-methylisoxazole-4-
propionic acid (AMPA) receptors expressed in Xenopus oocytes. The benzodiazepinones inhibited
AMPA-activated membrane current responses in a manner consistent with noncompetitive,
allosteric inhibition of the receptor-channel complex. The most potent compound in the series
was 1-(4-aminophenyl)-7,8-(methylenedioxy)-3,5-dihydro-4H-2,3-benzodiazepin-4-one (6), which
had an IC50 of 2.7 µM. For comparison, the reference compound GYKI 52466 (2) had an IC50
of 6.9 µM. Compound 6 also had potent anticonvulsant activity in a mouse maximum
electroshock-induced seizure (MES) assay: the ED50 was 2.8 mg/kg iv, whereas the ED50 for
GYKI 52466 was 4.6 mg/kg iv. In contrast to a previous report, the 7,8-dimethoxy analogue of
6 was a low-potency AMPA antagonist (IC50 >100 µM) and weak anticonvulsant (ED50 >10
mg/kg iv). The benzodiazepinones described herein are potent noncompetitive AMPA receptor
antagonists that could have therapeutic potential as anticonvulsants and neuroprotectants.
Ch a r t 1
In tr od u ction
L-Glutamate is the major excitatory neurotransmitter
in the mammalian central nervous system (CNS), and
glutamate receptors appear to play important roles in
all aspects of CNS function.1 Excessive stimulation of
ionotropic glutamate receptors can, however, initiate a
pathological cascade of events termed “excitotoxicity”.2
Excitotoxic processes are thought to cause much of the
neuronal death produced in acute neurodegenerative
disorders, and blockade of glutamate receptors is a
commonly pursued strategy for drug discovery programs
related to the treatment of stroke and traumatic brain
injury (TBI).3 Excitotoxicity and glutamate may also
play a role in chronic neurodegenerative conditions such
as Alzheimer’s and Parkinson’s disease.4
Ionotropic glutamate receptors are divided into three
classes depending on their sensitivity to the selective
agonists N-methyl-D-aspartate (NMDA), R-amino-3-
hydroxy-5-methylisoxazole-4-propionic acid (AMPA), and
kainic acid.5 Among these, AMPA receptors are the
principal mediators of fast excitatory neurotransmission
and occur abundantly throughout the CNS.6 The piv-
otal role of AMPA receptors in CNS function has
prompted a search for AMPA receptor antagonists
which could serve as therapeutically useful anticonvul-
sants and neuroprotectants.
are active across a broader range of ischemia models
than NMDA antagonists and do not induce psychoto-
mimetic behaviors or direct neurotoxicity.
In 1993 a second type of AMPA receptor antagonist
was reported.11 These compounds are 2,3-benzodiaz-
epines which inhibit AMPA receptor function by a
noncompetitive, allosteric mechanism.11 The prototypic
compounds, e.g., GKYI 52466 (2), have anticonvulsant
and neuroprotective properties in rodents.8,12 Subse-
quently, 1,2-dihydrophthalazines, such as SYM 2207
(4),13 and 2,3-benzodiazepin-4-ones, such as compound
5,14 were characterized as noncompetitive AMPA an-
tagonists with potencies comparable to that of GKYI
52466.
The first types of AMPA receptor antagonist reported
were competitive inhibitors such as NBQX (1) (Chart
1), PNQX, YM 90, and LY 293558.7 Competitive AMPA
antagonists have anticonvulsant properties in animals8
and are efficacious as neuroprotectants in animal
models of stroke, TBI, and spinal cord injury.9 The
latter studies even suggest that AMPA antagonists
might have advantages over NMDA antagonists as
neuroprotectants.3,10 In particular, AMPA antagonists
Herein we report that substituted 7,8-(methylene-
dioxy)-1-phenyl-3,5-dihydro-4H-2,3-benzodiazepin-4-
S0022-2623(98)00168-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 06/05/1998

2622 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14
Wang et al.
Sch em e 1a
Ta ble 1. In Vitro and In Vivo Potency of
2,3-Benzodiazepin-4-ones
a
b
AMPA IC50
,
MES ED50
,
entry
µM
mg/kg iv (95% CI)
10a
10b
10c
10d
10e
6
21.0 ( 1.9
12.9 (8.6-19.3)
16.0 (11.2-22.9)
NTc
>10
>10
2.8 (2.2-3.6)
4.6 (3.7-5.9)
>10
15.0 ( 0.70
23.0 ( 2.5
62.0 ( 4.8
56.0 ( 9.7
2.7 ( 0.17
6.9 ( 1.2
180 ( 7
2
5
a
IC50 values were calculated from inhibition of AMPA-activated
currents in Xenopus oocytes expressing rat cerebral cortex poly(A)+
RNA. The 2,3-benzodiazepinones were assayed on responses
elicited by 10 µM AMPA, i.e., currents constituting ∼80% of the
maximum AMPA response. At a holding potential of -70 mV the
average control current was ∼100 nA. Data are expressed as the
mean ( SEM estimated by curve fitting to pooled data from 3 to
b
4 separate experiments (see Figure 1). Seizures were induced in
a
male NSA mice (20-25 g) by application of current (50 mA, 60
pulses/s, 0.8-ms pulse width, 1-s duration) using a Ugo Basile
electroconvulsive treatment device (model 7801). Test compounds
were administered in 10% Tween-80 vehicle, iv, 5 min before
testing. Data are expressed as ED50 values with 95% confidence
intervals calculated by Litchfield and Wilcoxon analysis.21 c NT,
not tested.
(a) MeOH/H2SO4; (b) SnCl4/CH2Cl2/4-R-PhCOCl or P2O5/
ClCH2CH2Cl/4-R-PhCO2H; (c) H2NNH2; (d) CH3CO2H/H2/Pd/C.
ones, represented by compound 6, are potent, systemi-
cally active, noncompetitive AMPA receptor antagonists.
Ch em istr y
As outlined in Scheme 1, reaction of 3,4-(methylene-
dioxy)phenylacetic acid (7) with methanol in the pres-
ence of sulfuric acid provided the corresponding methyl
ester 8 in 86% yield. Friedel-Crafts acylation of 8 with
various acyl chlorides 4-R-PhCOCl (R ) a , H; b, CH3;
c, OCH3; d , F) with SnCl4 as the catalyst in CH2Cl2
furnished 9a -d in 18-63% yields.15 Compounds 9a -d
were refluxed with hydrazine hydrate in ethanol or
propanol to afford the 2,3-benzodiazepin-4-ones 10a -d
in 24-52% yields.16
Reaction of ester 8 with 4-nitrobenzoyl chloride under
the same conditions, however, did not give the desired
compound 9e, and the starting material 8 was recov-
ered. Since it was reported that P2O5 can effect
Friedel-Crafts reaction of acids with aromatic com-
pounds,17 ester 8 was refluxed with 4-nitrobenzoic acid
in ClCH2CH2Cl in the presence of P2O5 to provide 9e
in 50% yield. 2,3-Benzodiazepin-4-one 10e was obtained
by refluxing 9e with hydrazine in ethanol. Reduction
of the nitro group in 10e via hydrogenation in acetic
acid with Pd/C as the catalyst gave 6 in 68% yield.
F igu r e 1. Inhibition of AMPA receptors by 5 and 6. Mem-
brane current responses were recorded in Xenopus oocytes
expressing poly(A)+ RNA isolated from rat cerebral cortex.
Concentration-inhibition curves were measured on responses
elicited by 10 µM AMPA. Curves are the best fits of pooled
data to a four-parameter logistic equation.
initially screened at 10 mg/kg iv (n ) 8), with further
evaluation of dose-response functions using 4-5 doses
(n ) 15-24/dose). The dose required to produce protec-
tion against tonic seizures in 50% of mice (ED50) and
the associated 95% confidence intervals were calculated
based on the method of Litchfield and Wilcoxon.21
P h a r m a cology
The inhibitory potency of 2,3-benzodiazepin-4-ones in
vitro was assessed by measuring antagonism of AMPA-
activated membrane current responses in Xenopus
laevis oocytes expressing rat cerebral cortex poly(A)+
RNA.18 The mechanism of inhibition was investigated
by looking at the effect of a fixed concentration of
antagonist on the concentration-response curve for
AMPA. Using standard techniques,19 selected com-
pounds were also tested for inhibition of AMPA-
activated currents in cultured cortical neurons. The
statistical significance of differences between IC50 values
was tested by calculating pooled variances and the test
statistic t.20
Resu lts a n d Discu ssion
Potencies for inhibition of AMPA-activated currents
in oocytes of the 2,3-benzodiazepin-4-ones are given in
Table 1. Sample concentration-inhibition data and
curves are shown in Figure 1 for compounds 5 and 6.
The unsubstituted 2,3-benzodiazepin-4-one 10a had
moderate potency with an IC50 value of 21 µM. Sub-
stituting with electron-withdrawing groups, such as
fluoro 10d and nitro 10e, at the 4-position of the
benzene ring decreased potency to 62 and 56 µM,
respectively. In contrast, substituting with the electron-
donating group CH3 (10b) slightly enhanced potency to
15 µM (p ) 0.04). However, an OCH3 substituent (10c),
though a better electron-donating group than CH3, did
not increase potency. This argues that there is probably
The anticonvulsant activity of the 2,3-benzodiazepin-
4-ones was measured in vivo using a mouse maximum
electroshock-induced seizure (MES) assay as a rough
estimate of systemic bioavailability. Compounds were

Noncompetitive AMPA Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14 2623
ED50’s did not overlap. The unsubstituted and methyl-
substituted benzodiazepine-4-ones, 10a ,b, respectively,
were also active in the MES test, though their potencies
were 4-6-fold lower than that of 6. Compounds 5 and
10d ,e were inactive at 10 mg/kg iv and were not
evaluated further. In general, anticonvulsant activity
correlated well with potency at AMPA receptors. Again,
there appears to be disagreement with a previous study
where 5 was reported to have an ED50 of ∼5 mg/kg ip
in a mouse MES assay.14 Ataxia was assessed for 2 and
6 using the hanging wire test.24 The dose at which 50%
of mice fell from the wire, defined as the toxic dose
(TD50), and the 95% confidence intervals were calcu-
lated. The therapeutic index (TI) was defined as the
ED50/TD50. Compound 6 had a TD50 of 9.5 mg/kg (6.7-
13.5), indicating a TI of 3.4. This compound thus
displays a more favorable profile than 2, which exhibited
a similar TD50 of 10.3 mg/kg (8.5-12.5) resulting in a
TI of 2.3.
F igu r e 2. Noncompetitive inhibition of AMPA receptors by
6. Membrane current responses were recorded in Xenopus
oocytes expressing poly(A)+ RNA isolated from rat cerebral
cortex. Responses to AMPA were measured in the absence
(control) and presence of 6 (5 µM). Concentration-response
curves were fit to a four-parameter logistic equation.
a size-limited pocket at the 4-position. The amino
group, a strong electron-donating substituent, resulted
in the most potent 2,3-benzodiazepinone 6, which had
an IC50 of 2.7 µM. Tested side-by-side in oocytes, 6 was
∼3-fold more potent than the reference compound GYKI
52466 (2), which had an IC50 of 6.9 µM (p ) 0.03).
Levels of inhibition produced by 5 µM 6 were essentially
unaffected by changing the AMPA concentration from
3 to 100 µM (Figure 2). This is consistent with non-
competitive inhibition of AMPA receptor. The potency
of 6 as an antagonist of neuronal AMPA receptors was
checked by whole cell patch recordings from cultured
rat cortical neurons. Assayed under steady-state condi-
tions, 6 had an IC50 value on neuronal AMPA responses
of 2.9 ( 0.2 µM (n ) 5), almost identical to the value
measured in the oocyte experiments. The IC50 of 2 on
neuronal AMPA responses was 4.3 ( 0.4 (n ) 5), again
significantly weaker than 6 (p ) 0.01). Using standard
procedures, 6 (0.3-10 µM) was found to be inactive
Con clu sion
In conclusion, 6,7-(methylenedioxy)-1-phenyl-3,5-di-
hydro-4H-2,3-benzodiazepin-4-ones are a structurally
novel type of noncompetitive AMPA receptor antago-
nists. Compound 6 is a potent inhibitor which also has
good activity in vivo as an anticonvulsant. These types
of compounds may have therapeutic potential for the
treatment of epilepsy and neurodegenerative disorders.
Exp er im en ta l Section
Ch em istr y. All reagents were used as commercially re-
ceived from Aldrich or Fluka. Methylene chloride was distilled
from CaH2, anhydrous ClCH2CH2Cl ws used as received from
Aldrich, and other solvents were used without further puri-
1
fication. The H NMR spectra were recorded on a varian 300-
MHz spectrometer. Chemical shifts are in ppm (δ), and
coupling constants are in hertz. Melting points were measured
on a MEL-TEMP II melting point apparatus and are uncor-
rected. Elemental analyses were performed by Dersert Ana-
lytics.
Meth yl 3,4-(Meth ylen ed ioxy)p h en yla ceta te (8). To a
solution of 3,4-(methylenedioxy)phenylacetic acid (4.2 g, 23
mmol) in methanol (50 mL) was added concentrated sulfuric
acid (1.5 mL). The mixture was refluxed for 48 h, cooled to
room temperature, and neutralized with saturated NaHCO3.
The methanol was removed in vacuo. The residue was
extracted with 1:1 hexane/EtOAc (2 × 100 mL). The combined
organic phase was washed with water, saturated NaHCO3, and
brine and dried over Na2SO4. The solvent was removed in
vacuo to yield the title compound as an oil (3.9 g, 86%): 1H
NMR (CDCl3) 6.78-6.72 (m, 3H), 5.95 (s, 2H), 3.69 (s, 3H),
3.54 (s, 2H).
Meth yl 2-Ben zoyl-4,5-(m eth ylen ed ioxy)p h en yla ceta te
(9a ). To a solution of methyl 3,4-(methylenedioxy)phenylac-
etate (150 mg, 0.77 mmol) in CH2Cl2 (5 mL) was added SnCl4
(1.0 M solution in CH2Cl2; 1.5 mL, 1.5 mmol) at 0 °C. Then
benzoyl chloride (130 µL, 1.1 mmol) was added. The reaction
mixture was allowed to warm to room temperature slowly.
After 24 h, the mixture was added to a saturated NaHCO3
solution (30 mL), diluted with 1:1 hexane/EtOAc (60 mL),
washed with water and brine, and dried over Na2SO4. The
solvent was removed in vacuo, and the resulting residue was
purified by chromatography (4:1 hexane/EtOAc) to yield the
title compound (110 mg, 48%): 1H NMR (CDCl3) 7.78-7.45
(m, 5H), 6.88 (s, 1H), 6.84 (s, 1H), 6.04 (s, 2H), 3.80 (s, 2H),
3.61 (s, 3H).
when assayed for modulation of recombinant human
22
GABAA receptors (R1â2γ2L
)
and rat NMDA (1A/2B)19
receptors expressed in oocytes (data not shown).
Differing from a previous report,14 the open-ring
dimethoxy-2,3-benzodiazepin-4-one 5 had an IC50 of 180
µM on AMPA responses in oocytes (Figure 1), i.e., ∼70-
fold weaker than the corresponding methylenedioxy
analogue 6 and ∼25-fold less active than GYKI 52466
(2). Reasons for this discrepancy remain uncertain. In
oocyte assays GYKI 52322 (3),23 the dimethoxy analogue
of GYKI 52466, is also a weak AMPA antagonist (IC50
> 200 µM). In the previous study,14 the potency of 5
was estimated by electrical recordings from guinea pig
brain slices, as opposed to oocytes. Yet, we see a close
correlation between oocyte and neuronal data so this
inconsistency does not conjure a ready explanation for
differences in potency. Since the methylenedioxy ring
is much smaller than the dimethoxy, the SAR of GYKI
compounds and 2,3-benzodiazepin-4-ones suggested that
there might be a size-limited pocket at the 7- and
8-positions of 2,3-benzodiazepines.
Compound 6 was found to exhibit anticonvulsant
efficacy with an ED50 of 2.8 mg/kg iv (Table 1) in the
MES assay. These effects were more potent than those
of GYKI 52466 (2) which had an ED50 of 4.6 mg/kg. This
appears to be a significant improvement in in vivo
potency in that the 95% confidence intervals around the
Compounds 9b-d were prepared in a manner similar to
that for 9a .
Meth yl 2-(4-Meth ylben zoyl)-4,5-(m eth ylen ed ioxy)p h e-
n yla ceta te (9b). From methyl 3,4-(methylenedioxy)pheny-

2624 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 14
Wang et al.
lacetate (319 mg, 1.64 mmol), CH2Cl2 (5 mL), SnCl4 (1.0 M
solution in CH2Cl2; 3.5 mL, 3.5 mmol), and 4-toluoyl chloride
(260 µL, 1.97 mmol) was obtained 9b as an oily solid (90 mg,
18%): 1H NMR (CDCl3) 7.69 (d, J ) 8.0, 2H), 7.24 (d, J ) 8.0,
2H), 6.88 (s, 1H), 6.83 (s, 1H), 6.03 (s, 2H), 3.78 (s, 2H), 3.60
(s, 3H), 2.43 (s, 3H).
J ) 8.5, 5.5, 2H), 7.11 (dd, J ) 8.5, 8.5, 2H), 6.83 (s, 1H), 6.61
(s, 1H), 6.04 (s, 2H), 3.45 (s, 2H). Anal. (C16
C, H, N.
H11FN2O3‚1/8H2O)
7,8-(Met h ylen ed ioxy)-1-(4-n it r op h en yl)-3,5-d ih yd r o-
4H-2,3-ben zod ia zep in -4-on e (10e). A mixture of methyl 4,5-
(methylenedioxy)-2-(4-nitrobenzoyl)phenylacetate (20 g, 58
mmol) and hydrazine hydrate (7 mL, 124 mmol) in ethanol
(150 mL) was refluxed for 5 h. Then 6 N HCl (10 mL) was
added, and the mixture was further refluxed for 3 h. After
cooling, the resulting yellow solid was collected by filtration,
washed with water, and dried in vacuo to yield the title
compound (10.5 g, 32 mmol, 55%) as a solid: mp 293-295 °C;
1H NMR (DMSO-d6) 11.2 (s, 1H), 8.31(d, J ) 8.8, 2H), 7.79 (d,
J ) 8.8, 2H), 7.13 (s, 1H), 6.65 (s, 1H), 6.12 (s, 2H), 3.45 (s,
2H). Anal. (C16H11N3O5) C, H, N.
1-(4-Am in op h en yl)-7,8-(m eth ylen ed ioxy)-3,5-d ih yd r o-
4H-2,3-ben zod ia zep in -4-on e (6). To a suspension of 7,8-
(methylenedioxy)-1-(4-nitrophenyl)-3,5-dihydro-4H-2,3-benzo-
diazepin-4-one (1.3 g, 4.0 mmol) in acetic acid (30 mL) was
added 5% Pd/C (130 mg). The mixture was shaken under
hydrogen (40 psi) for 18 h. The Pd/C was filtered out. The
filtrate was concentrated, diluted with 2 N HCl (50 mL),
washed with EtOAc (3 × 30 mL), neutralized with 2 N NaOH,
and extracted with EtOAc (150 mL). The organic phase was
washed with water and brine, dried over Na2SO4, and con-
centrated in vacuo to yield the title compound as a yellow solid
(0.8 g, 2.7 mmol, 68%): mp 242-244 °C; 1H NMR (CDCl3) 8.32
(s, 1H), 7.41 (d, J ) 8.5, 2H), 6.81 (s, 1H), 6.70 (s, 1H), 6.68 (d,
J ) 8.5, 2H), 6.02 (s, 2H), 3.94 (brs, 2H), 3.42 (s, 2H). Anal.
(C16H13N3O3‚1/4H2O) C, H; N: calcd, 14.02; found, 13.48.
Electr op h ysiology. Total RNA was prepared from rat
cerebral cortex by homogenization in 6 M urea/3 M LiCl
followed by phenol/chloroform extraction. Polyadenylated
(poly(A)+) RNA was isolated from total cellular RNA by oligo-
dT cellulose chromatography. Xenopus oocytes were prepared
for injection by the method of Woodward et al.18 Oocytes were
microinjected with approximately 25 ng of cortical poly(A)+
RNA and stored in Barth’s medium (containing in mM: NaCl,
88; KCl, 1; CaCl2, 0.41; Ca(NO3)2, 0.33; MgSO4, 0.82; NaHCO3,
2.4; HEPES, 5; pH 7.4, with 0.1 mg/mL gentamycin sulfate)
for 4-16 days prior to recording. Membrane current responses
were recorded in frog Ringer solution containing (in mM):
NaCl, 115; KCl, 2; CaCl2, 1.8; HEPES, 5; pH 7.4. Electrical
recordings were made using a conventional two-electrode
voltage clamp (Dagan TEV-200). The oocyte was placed in a
5-mL chamber lined with nylon mesh, impaled with two
microelectrodes and voltage-clamped at a holding potential of
-70 mV. A microcapillary linear array system was used to
superfuse the oocyte in Ringer solution and to apply drugs and
wash solutions. A control concentration (10 µM) of AMPA was
applied to the oocyte to determine a baseline membrane
current response. The inhibition of this response by 2,3-
benzodiazepin-4-ones was measured by applying increasing
concentrations of the antagonist in Ringer solution for ∼30 s
followed by coapplication of the inhibitor with 10 µM AMPA.
The resulting membrane current responses were fit to a four-
parameter logistic equation (Origin, Microcal Software, Inc.).
All electrophysiological data are expressed as mean ( standard
error of the mean (SEM) to two significant figures.
Met h yl 2-(4-Met h oxyb en zoyl)-4,5-(m et h ylen ed ioxy)-
p h en yla ceta te (9c). From methyl 3,4-(methylenedioxy)-
phenylacetate (244 mg, 1.26 mmol), CH2Cl2 (5 mL), SnCl4 (1.0
M solution in CH2Cl2; 2.5 mL, 2.5 mmol), and 4-anisoyl chloride
(220 µL, 1.62 mmol) was obtained 9c as a white solid (110 mg,
27%): 1H NMR (CDCl3) 7.78 (d, 2H, J ) 8.6), 6.93 (d, 2H, J )
8.6), 6.86 (s, 1H), 6.83 (s, 1H), 6.03 (s, 2H), 3.88 (s, 3H), 3.75
(s, 2H), 3.59 (s, 3H).
Meth yl 2-(4-F lu or oben zoyl)-4,5-(m eth ylen ed ioxy)p h e-
n yla ceta te (9d ). From methyl 3,4-(methylenedioxy)pheny-
lacetate (340 mg, 1.75 mmol), CH2Cl2 (8 mL), SnCl4 (1.0 M
solution in CH2Cl2; 3.5 mL, 3.5 mmol), and 4-fluorobenzoyl
chloride (270 µL, 2.28 mmol) was obtained 9d as a solid (350
mg, 63%): 1H NMR (CDCl3) 7.81 (m, 2H), 7.13 (m, 2H), 6.85
(s, 1H), 6.84 (s, 1H), 6.04 (s, 2H), 3.79 (s, 2H), 3.61 (s, 3H).
Meth yl 4,5-(Meth ylen ed ioxy)-2-(4-n itr oben zoyl)p h en y-
la ceta te (9e). To a solution of methyl 3,4-(methylenedioxy)-
phenylacetate (5.4 g, 28 mmol) in ClCH2CH2Cl (100 mL) were
added 4-nitrobenzoic acid (7.2 g, 43 mmol) and P2O5 (18 g) at
room temperature under argon. The mixture was refluxed for
28 h, cooled to room temperature, and then diluted slowly by
addition of cold water. The resulting mixture was carefully
neutralized with solid K2CO3 and extracted with 1:1 hexane/
EtOAc (2 × 300 mL). The combined extracts were washed
with water and brine and dried over Na2SO4. The solvent was
removed in vacuo, and the resulting residue was purified by
chromatography (3:1 hexane/EtOAc) to afford the title com-
pound as a yellow solid (4.7 g, 14 mmol, 50%): 1H NMR
(CDCl3) 8.32 (d, J ) 8.5, 2H), 7.92 (d, J ) 8.5, 2H), 6.85 (s,
1H), 6.81 (s, 1H), 6.07 (s, 2H), 3.88 (s, 2H), 3.63 (s, 3H).
7,8-(Meth ylen ed ioxy)-1-p h en yl-3,5-d ih yd r o-4H-2,3-ben -
zod ia zep in -4-on e (10a ). A solution of methyl 2-benzoyl-4,5-
(methylenedioxy)phenylacetate (110 mg, 0.37 mmol) and
hydrazine hydrate (30 µL, 0.53 mmol) in ethanol (15 mL) was
refluxed for 5 days. The solvent was removed in vacuo, and
the resulting residue was purified by chromatography to yield
the title compound (30 mg, 0.11 mmol, 29%): mp 182-184 °C;
1H NMR (CDCl3) 8.59 (s, 1H), 7.60-7.41 (m, 5H), 6.83 (s, 1H),
6.63 (s, 1H), 6.03 (s, 2H), 3.46 (s, 2H). Anal. (C16H12N2O3‚
1/4H2O) C, H, N.
Compounds 10b-d were prepared in a manner similar to
that of 10a .
7,8-(Meth ylen ed ioxy)-1-(4-m eth ylp h en yl)-3,5-d ih yd r o-
4H-2,3-ben zod ia zep in -4-on e (10b). From methyl 4,5-(me-
thylenedioxy)-2-(4-methylbenzoyl)phenylacetate (90 mg, 0.29
mmol), hydrazine hydrate (50 µL, 0.88 mmol), and acetic acid
(40 µL) in ethanol (10 mL) was obtained 10b as a solid in 52%
yield: mp 222-224 °C; 1H NMR (CDCl3) 8.36 (s, 1H), 7.48 (d,
J ) 8.0, 2H), 7.23 (d, J ) 8.0, 2H), 6.82 (s, 1H), 6.64 (s, 1H),
6.02 (s, 2H), 3.45 (s, 2H), 2.41 (s, 3H). Anal. (C17H14N2O3) C,
H, N.
1-(4-Meth oxyph en yl)-7,8-(m eth ylen edioxy)-3,5-dih ydr o-
4H-2,3-ben zod ia zep in -4-on e (10c). From methyl 4,5-(me-
thylenedioxy)-2-(4-methoxybenzoyl)phenylacetate (102 mg, 0.31
mmol) and hydrazine hydrate (30 µL, 0.53 mmol) in 1-propanol
(8 mL) was obtained 10c as a solid in 24% yield at 31%
conversion: mp 194-196 °C; 1H NMR (CDCl3) 8.48 (s, 1H),
7.55 (d, J ) 8.8, 2H), 6.94 (d, J ) 8.8, 2H), 6.83 (s, 1H), 6.66
(s, 1H), 6.03 (s, 2H), 3.86 (s, 3H), 3.44 (s, 2H). Anal.
(C17H14N2O4) C, H, N.
In Vivo P h a r m a cology. Male NSA mice weighing be-
tween 15 and 20 g were obtained from Harlan Sprague-
Dawley (San Diego, CA). Compounds were dissolved/sus-
pended in Tween 80 (10%)/distilled water (90%), and were
placed in solution/suspension by warming and sonication for
1-4 h. Solutions were prepared on a weight/volume basis on
the day of or evening prior to use. Compounds were admin-
istered intravenously (iv). All drugs were administered in
volumes of 200 mL/20 g. Seizures were induced by application
of current (50 mA, 60 pulses/s, 0.8-ms pulse width, 1-s
duration, d.c.) using a Ugo Basile electroconvulsive treatment
device (model 7801). Mice were restrained by gripping the
loose skin on their dorsal surface, and saline-coated corneal
electrodes were held lightly against the two corneas. Current
was applied and animals were observed for a period of up to
1-(4-F lu or op h en yl)-7,8-(m eth ylen ed ioxy)-3,5-d ih yd r o-
4H-2,3-ben zod ia zep in -4-on e (10d ). From methyl 2-(4-fluo-
robenzoyl)-4,5-(methylenedioxy)phenylacetate (350 mg, 1.11
mmol), hydrazine hydrate (180 µL, 3.18 mmol), and acetic acid
(50 µL) in ethanol (10 mL) was obtained 10d as a solid in 31%
yield: mp 205-207 °C; 1H NMR (CDCl3) 8.45 (s, 1H), 7.59 (dd,

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30 s for the occurrence of a tonic hindlimb extension in excess
of 90° from the plane of the body. The hanging wire test has
been described previously24 and used a custom built apparatus
that consisted of a metal wire (2-mm diameter) suspended
horizontally above the benchtop (25 cm). Mice were held by
the base of the tail, their forepaws placed in contact with the
wire, and then released. Animals were required to bring at
least one hindpaw in contact with the wire within 10 s in order
to be scored as a pass. The dose of drug required to produce
an anticonvulsant effect (ED50) or motor impairment (TD50
)
in 50% of animals and its associated 95% confidence limits
were calculated by the method of Litchfield and Wilcoxon21
using a commercial computer program (PHARM/PCS v4.2,
MicroComputer Specialists). The protective index (PI) was
calculated by dividing the TD50 by the ED50
.
Ack n ow led gm en t. We thank Dr. George Field and
Dr. J on Hawkinson for helpful discussions, Dr. E. R.
Whittemore for preparing neuronal cell cultures, and
Michael Suruki and Silvia Robledo for animal testing.
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