Effects of a 3-alkyl-, 4-hydroxy- and/or 8-aromatic-substituent on the phenylethanolamine N-methyltransferase inhibitor potency and α2-adrenoceptor affinity of 2,3,4,5-tetrahydro-1H-2-benzazepines

Article abstract of DOI:10.1016/S0968-0896(01)00112-2

2,3,4,5-Tetrahydro-1H-2-benzazepine (THBA; 1) is nearly 100-fold more selective an inhibitor of phenylethanolamine N-methyltransferase (PNMT, EC 2.1.1.28) versus the α₂-adrenoceptor than is 1,2,3,4-tetrahydroisoquinoline (THIQ; 2) (1: PNMT K

Full text of DOI:10.1016/S0968-0896(01)00112-2

Bioorganic & Medicinal Chemistry 9 (2001) 1957–1965
Effects of a 3-Alkyl-, 4-Hydroxy- and/or 8-Aromatic-substituent
on the Phenylethanolamine N-Methyltransferase Inhibitor Potency
and ꢀ2-Adrenoceptor Affinity of 2,3,4,5-Tetrahydro-1H-2-
benzazepines
Gary L. Grunewald,* Vilas H. Dahanukar1 and Kevin R. Criscione
Department of Medicinal Chemistry, 4060 Malott Hall, School of Pharmacy, University of Kansas, Lawrence, KS 66045, USA
Received 10 December 2000; accepted 9 February 2001
Abstract—2,3,4,5-Tetrahydro-1H-2-benzazepine (THBA; 1) is nearly 100-fold more selective an inhibitor of phenylethanolamine N-
methyltransferase (PNMT, EC 2.1.1.28) versus the a2-adrenoceptor than is 1,2,3,4-tetrahydroisoquinoline (THIQ; 2) (1: PNMT
Ki=3.3 mM, a2-adrenoceptor Ki=11 mM, selectivity [a2 Ki/PNMT Ki]=3.3; 2: PNMT Ki=9.7 mM, a2 Ki=0.35 mM, selectiv-
ity=0.036;). Since the PNMT inhibitory activity and selectivity of THIQ were enhanced by the introduction of a hydrophilic elec-
tron-withdrawing 7-substituent and a 3-alkyl-substituent, a similar study was conducted on THBA. 8-Nitro-THBA (3) was found
to be as potent an inhibitor of PNMT as its THIQ analogue (21) and to be more selective due to its reduced a2-adrenoceptor affinity
(3: PNMT Ki=0.39 mM, a2 Ki=66 mM, selectivity=170; 21: PNMT Ki=0.41 mM, a2 Ki=4.3 mM, selectivity=10). Introduction of a
3-alkyl substituent on the THBA nucleus decreased both the a2-adrenoceptor affinity and the PNMT inhibitory activity, suggesting
an area of steric bulk intolerance at both sites. 4-Hydroxy-THBA (15), which can be considered a conformationally-restricted
analogue of 3-hydroxymethyl-THIQ (30), exhibited poorer PNMT inhibitory activity and less selectivity than 30 (15: PNMT
Ki=58 mM, a2 Ki=100 mM, selectivity=1.7; 30: PNMT Ki=1.1 mM, a2 Ki=6.6 mM, selectivity=6.0). While the addition of an 8-
nitro group to 15 increased the selectivity of 16 as compared to its THIQ analogue (31), it was not as potent at PNMT nor as
selective as 8-nitro-THBA (3) (16, PNMT Ki=5.3 mM, a2 Ki=680 mM, selectivity=130; 31: PNMT Ki=0.29 mM, a2 Ki=19 mM,
selectivity=66). Compound 3 is the most selective (PNMT/a2) and one of the more potent at PNMT compounds yet reported in the
benzazepine series, and should have sufficient lipophilicity to penetrate the blood–brain barrier (CLogP=1.8). # 2001 Elsevier
Science Ltd. All rights reserved.
In our ongoing study into the development of a selective
and potent inhibitor of the enzyme phenylethanolamine
N-methyltransferase (PNMT, EC 2.1.1.28)—that cata-
lyzes the final step in the biosynthesis of epinephrine—
we report our findings in a benzazepine series of inhibi-
tors. To elucidate the exact role of epinephrine in the
central nervous system (CNS), an inhibitor of PNMT
lacking activity at other pharmacologically relevant sites
(especially the a2-adrenoceptor) is highly desired.2 In
addition, such an inhibitor must have low polarity so
that it can penetrate the blood–brain barrier (BBB) to
exert its effect in the CNS.
Ki=3.3 mM, a2 Ki=11 mM, selectivity (a2 Ki/PNMT
Ki)=3.3] provided higher PNMT inhibitory potency
and lower a2-adrenoceptor affinity as compared to other
conformationally-restricted benzylamine analogues.3
1,2,3,4-Tetrahydroisoquinoline (2, THIQ, PNMT
Ki=9.7 mM, a2 Ki=0.35 mM, selectivity=0.036) was
relatively less potent in inhibiting PNMT and also less
selective than THBA. Subsequently, a hydrophilic elec-
tron-withdrawing 7-substituent4 or
a 3-alkyl sub-
stituent5 was found to be an important structural
feature that influenced the potency and selectivity of
THIQ, and the combination of both on THIQ was
found to exhibit a synergistic effect on the selectivity for
PNMT versus the a2-adrenoceptor.6 These encouraging
results from studies in the THIQ series prompted us to
investigate the influence of similar substituents on the
potency and selectivity of the THBA nucleus. The aro-
matic substituents to be studied (e.g., NO2, SO2Me and
SO2NH2) were those that were found to have the largest
The conformational restriction of benzylamine into a
2,3,4,5-tetrahydro-1H-2-benzazepine [THBA, 1, PNMT
*Corresponding author. Tel.:+1-785-864-4497; fax: +1-785-864-
5326; e-mail: ggrunewald@ukans.edu
0968-0896/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(01)00112-2

1958
G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
influence on selectivity in the THIQ series.4 Some of
these 8-substituted-THBAs had been listed previously in
the patent literature,7 but the Ki values for PNMT inhi-
bition and a2-adrenoceptor affinity were not reported.
solution of 1 in concentrated sulfuric acid. 8-Nitro-
THBA (3) was isolated in 60% yield along with a minor
quantity (7%) of 6,8-dinitro-THBA (17). Catalytic
reduction of 3 to 4, followed by Sandmeyer bromination
gave 5, which was protected and subjected to a halogen-
metal exchange reaction. The lithiated species was trap-
ped at low temperature with methyl disulfide and the
trityl protecting group was cleaved to yield 6. The thio-
methyl ether 6 was readily oxidized under acidic condi-
tions to yield sulfone 7 (Scheme 1).
8-Aminosulfonyl-THBA (8) was prepared from amide
19,8,9 the product of a Schmidt reaction on 1-tetralone.
Due to the meta-directing effect of the amido group,
only a single regioisomer was obtained from the chlor-
osulfonation of 19, which was converted to sulfonamide
20 (Scheme 2). Borane reduction of 20 was slow due to
its low solubility in THF. An acidic work up permitted
isolation of the amphoteric product (8) as its hydro-
chloride salt (Scheme 2).
As proposed earlier,3 the enhancement in PNMT inhi-
bitory potency of 1 as compared to 2 probably arose
from the puckered 3-methylene group in the bioactive
conformation of 1 that interacted favorably at a spa-
tially compact region in the PNMT active site. In con-
trast, the same methylene group in THBA might be
involved in a negative steric interaction at the a2-adre-
noceptor. This hypothesis also explained the improved
potency and selectivity of 3-methyl-THIQ6 [28, PNMT
Ki=2.1 mM, a2 Ki=0.76 mM, selectivity (a2 Ki/PNMT
Ki)=0.36] as compared to 2. To explore the effects of
the introduction of a 3-methyl substituent alone and in
conjunction with an electron-withdrawing group on the
THBA nucleus, analogues 9 and 10 were prepared.
The synthesis of other THBAs was developed in our
laboratory using the Schmidt reaction (analogues 9–14)8
and a lactone to lactam rearrangement (analogues 15
and 16),9 that has been reported previously.
Biochemistry. All the compounds were evaluated as
their hydrochloride or oxalate salts. In vitro PNMT
activity was assessed by use of a standard radiochemical
assay—using three different inhibitor concentrations
The 3-hydroxymethyl substituent, with or without a
hydrophilic electron-withdrawing 7-substituent, was
found to be effective in enhancing the selectivity of the
THIQ nucleus.6 Hence, THBAs bearing a 3-hydroxy-
methyl substituent and an 8-aromatic substituent (11–
14) were investigated. As a more direct comparison of
the effect of the 3-hydroxymethyl substituent, 4-
hydroxy-THBA (15)—a conformationally-constrained
analogue of 3-hydroxymethyl-THIQ (30), where the
side-chain is incorporated into the ring system—was
also investigated, along with its 8-nitro analogue (16).
Since THBA (1) is more selective for PNMT versus the
a2-adrenoceptor than is THIQ (2), and the addition of a
3-alkyl or a 7-substituent on the THIQ nucleus
improved selectivity for PNMT,4,6 would 3-alkyl or
judicious 8-substitution on the THBA nucleus improve
selectivity for PNMT, and thus provide a viable phar-
macological tool for the purpose of studying the func-
tion of epinephrine in the brain?
Scheme 1. Reagents and conditions: (a) KNO3, H2SO4; (b) H2, PtO2,
HCl; (c) NaNO2, HBr, CuBr; (d) PH3CCl, Et3N, DMAP; (e) n-BuLi,
THF ꢀ78 ꢁC; (f) CH3SSCH3, 3 N HCl, Acetone; (g) CF3CO3H (2
equiv), CF3CO2H.
Chemistry
The chemistry used in the synthesis of 8-substituted-
THBAs is similar to that developed earlier for the THIQ
system4 (Scheme 1). Nitration of THBA (1) was carried
out by addition of potassium nitrate to an ice-cold
Scheme 2. Reagents and conditions: (a) ClSO3H; (b) NH4OH; (c)
BH3THF, reflux.

G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
1959
with phenylethanolamine as the variable substrate—
that has been described previously.10 Bovine adrenal
PNMT used for the in vitro assay was purified accord-
ing to the procedure of Connett and Kirshner11 through
the isoelectric precipitation step.
8-Nitro-THBA (3) was found to be the most selective
inhibitor in the THBA series, with a selectivity
approximately that of SK&F 29661 (26). However, it
had been reported that 26 did not penetrate into the
CNS, possibly due to its high polarity.13 Therefore, the
higher lipophilicity of 3 may enable it to penetrate the
BBB (26: calculated log P (CLogP)=ꢀ0.39 versus 3:
CLogP=1.8).14,15 It was interesting to note that 3
exhibited lower a2-adrenoceptor affinity than 3-methyl-
7-nitro-THIQ6 (27: PNMT Ki=0.49 mM, a2 Ki=31 mM,
selectivity=63), which would suggest that the extra ring
methylene (corresponding to the methyl group in 27)
encounters more steric bulk intolerance at the a2-adre-
noceptor.6
a2-Adrenergic receptor binding assays were performed
using cortex obtained from male Sprague–Dawley
rats.12 [3H]Clonidine was used as the radioligand to
define the specific binding and phentolamine was used
to define the non-specific binding. Clonidine was used as
the ligand to define a-adrenergic binding affinity to
simplify the comparison with previous results.
Results and Discussion
The results of biochemical evaluation of the 8-sub-
stituted-THBAs are presented in Table 1 along with the
results for the corresponding 7-substituted-THIQs.4
Compounds 3–8 were reported as being synthesized in
the patent literature,7 but no data was reported. The
results for 3-alkyl-substituted-THBAs and 4-hydroxy-
THBAs are listed in Tables 2and 3, respectively. As
expected, all of these THBA derivatives exhibited com-
petitive kinetics in binding to PNMT, and a Hill coeffi-
cient close to unity in a2-adrenoceptor binding assays.
The introduction of a 3-methyl or 3-hydroxymethyl
group increased the PNMT inhibitory potency in the
THIQ series,6 but decreased it in the THBA series. The
addition of an 8-substituent did not overcome the dele-
terious effect of the 3-alkyl group, which may be
involved in negative steric interactions that prevent the
optimal binding of the THBA nucleus. This result was
consistent with the decreased PNMT inhibitory potency
of 3-ethyl-THIQ (29: PNMT Ki=24 mM)5 as compared
to 28 (PNMT Ki=2.1 mM).
Examination of the data for the 8-substituted-THBAs
showed that, as in the THIQ series,4 the aromatic sub-
stituent had considerable influence on the PNMT inhi-
bitory potency. Comparison of an 8-substituted-THBA
derivative with the corresponding 7-substituted-THIQ
showed that: (a) the potency of the nitro-, bromo-, and
amino-derivatives at PNMT were unaffected by an
increase in ring size, (b) the PNMT inhibitory activity of
the sulfonyl-analogues was decreased in the benzazepine
series, and (c) the THBA derivatives showed lower a2-
adrenoceptor affinity than the corresponding THIQ
derivatives, except in the case of the 8-sulfonyl-sub-
stituted-THBAs, which had similar affinities.
The trends in a2-adrenoceptor affinity of the 3-alkyl-
THBAs paralleled the results obtained in the 3-alkyl-
THIQ series,6 with the 3-hydroxymethyl substituent
resulting in a greater decrease in a2-adrenoceptor affi-
nity than the 3-methyl substituent. However, none of these
compounds were more selective than 8-nitro-THBA (3).
Table 1. In vitro activities of 7-substituted-1,2,3,4-tetrahydroisoquinolines and 8-substituted-2,3,4,5-tetrahydro-1H-2-benzazepines as inhibitors of
PNMT and of the binding of [3H]clonidine to the a2-adrenoceptor
Compd
na
R
H
PNMTKiꢂSEM (mM)
a2KiꢂSEM (mM)
a2/PNMT selectivity
2
1
21
3
22
4
23
5
24
6
25
7
26
8
1
2H
1
2NO
1
2NH
1
2Br
1
2SMe
1
2SO
1
2SO
9.7ꢂ0.4
ꢂ0.211
0.35ꢂ0.1
ꢂ1
0.036
3.3
10
170
0.11
4.6
3.3
NO2
0.41ꢂ0.05
0.39ꢂ0.05
27ꢂ3
4.3ꢂ0.3
66ꢂ3
2
NH2
3.1ꢂ0.1
110ꢂ10
0.23ꢂ0.13
8.8ꢂ0.230
0.41ꢂ0.05
12ꢂ1
24ꢂ1
2
Br
0.29ꢂ0.03
ꢂ0.04
0.79
9
0.2
1.1
SMe
0.61ꢂ0.05
ꢂ0.1
0.67
11
120
19
180
54
SO2Me
2Me
SO2NH2
2NH2
1.3ꢂ0.06
7.7ꢂ0.23
0.55ꢂ0.04
1.7ꢂ0.09
160ꢂ10
150ꢂ10
100ꢂ20
91ꢂ3
aData for n=1 taken from ref. 4.

1960
G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
As both of the 8-sulfonyl-substituents reduced the
PNMT inhibitory potency of THBA, these were not
introduced on the 3-alkyl-THBAs. We determined the
a2-adrenoceptor affinity of a previously reported5
PNMT inhibitor, 29 (a2 Ki=0.66 mM)6 and found that
its a2-adrenoceptor affinity was almost identical to that
of 28 (a2 Ki=0.76 mM), which suggested that the term-
inal methyl group in the ethyl side chain might be
oriented in a region of space where steric bulk was
tolerated. In contrast, the 3-methyl group in 9 (a2
Ki=89 mM) appears to be projected into a region of
steric bulk intolerance at the a2-adrenoceptor.
Inclusion of the methylene group of the hydroxymethyl
side chain of 30 (PNMT Ki=1.1 mM, a2 Ki=6.6 mM,
selectivity=6.0)6 into the ring (analogue 15) resulted in
a 50-fold loss in PNMT inhibitory activity (PNMT
Ki=58 mM). Thus, 15 is apparently not a satisfactory
conformationally-restricted analogue of the binding
orientation of 30. This result is consistent with mole-
cular modeling studies on the (R)- and (S)-enantiomers
of 15, which show that the low energy global or local
minimum conformations (not exceeding the energy of
the corresponding global minimum by more than 2
kcal/mole, as determined by the grid search option in
SYBYL16) could be fitted reasonably well [root mean
square of fit=0.240 for (R)-15), and 0.241 for (S)-15]
with the more active (R)-enantiomer6 of 30. However,
as shown in Table 4 and Figure 1, the minimum
distances between the putative binding groups of (R)- or
(S)-15 with the more active (R)-enantiomer6 of 30,
would seem to preclude these groups binding at the
same region in space at the PNMT active site.
Table 2. In vitro activities of racemic 7-substituted-3-alkyl-1,2,3,4-
tetrahydroisoquinolines and 8-substituted-3-alkyl-2,3,4,5-tetrahydro-
1H-2-benzazepines as inhibitors of PNMT and of the binding of
[3H]clonidine to the a2-adrenoceptor
KiꢂSEM (mM)
Selectivity
Compd na
R
R3
PNMT
a2
a2/PNMT
9
2H
1
2NO
Me
8.6
ꢂ0.4
2.1ꢂ0.1
5.5ꢂ0.3
0.49ꢂ0.05
7.8ꢂ0.3
1.1ꢂ0.1
8.1ꢂ0.4
89ꢂ3
0.76ꢂ0.08
120ꢂ10
31ꢂ1
10
0.36
22
63
28
6.0
67
66
28
10
27
11
30
12
31
13
14
H
Me
Me
Me
2
1
2
1
NO2
H
CH 2OH
CH2OH
CH2OH
220ꢂ10
6.6ꢂ0.6
540ꢂ10
19ꢂ1
As in the case of the unsubstituted THBA (1), the addi-
tion of an 8-nitro substituent to 15—compound 16—
improved the PNMT inhibitory potency by about 10-
fold. However, the deleterious interaction of the 4-
hydroxy group, as in 15, was not totally overcome. The
lowered a2-adrenoceptor affinity of 16 was due to the
combined effect of the 4-hydroxy and the 8-nitro
groups, but while this resulted in a selectivity ratio that
was higher than that of its THIQ analogue (31: PNMT
Ki=0.29 mM, a2 Ki=19 mM, selectivity=66), 16 was not
as potent at PNMT.
H
2NO
1
2NH
2Br
2
NO2 CH2OH 0.29ꢂ0.04
CH2OH 440ꢂ30
490ꢂ10
58ꢂ1
1.1
9.7
2
CH
2OH
6.0ꢂ0.3
aData for n=1 taken from ref 6.
Table 3. In vitro activities of racemic 4-hydroxy-2,3,4,5-tetrahydro-
1H-2-benzazepines as inhibitors of PNMT and of the binding of
[3H]clonidine to the a2-adrenoceptor
Summary and Conclusions
We have investigated the effects of an 8-substituent in
the THBA system on PNMT inhibitory potency and a2-
adrenoceptor affinity. Compounds 3 and 16 were the
most selective of the THBAs studied, with both dis-
playing selectivities (a2 Ki / PNMT Ki) greater than 100.
These compounds are also more lipophilic (3,
CLogP=1.75; 16, CLogP=0.44) than SK&F 29661 (26,
CLogP=ꢀ0.38)—which did not penetrate the BBB13—
and may be able to penetrate into the CNS.14 Unlike the
results found in the THIQ series, the sulfonyl sub-
stituents lowered the PNMT inhibitory activity of
THBA (1). The PNMT inhibitory potencies of the 3-
alkyl- (9–14) and the 4-hydroxy-THBAs (15–16) were
lower than those seen for THBA (1), and the intro-
duction of an 8-substituent was unsuccessful in redu-
cing the PNMT Ki for the 3-alkyl-THBAs. While the
addition of an 8-nitro substituent to 15 increased its
PNMT inhibitory potency, the deleterious effect of
the 4-hydroxy group caused 16 to be less active at
PNMT than unsubstituted THBA (1). However, the
a2-adrenoceptor affinities of these compounds were
substantially lower in comparison with the corre-
sponding THIQ derivatives, leading to overall higher
Compd
R8
PNMT
KiꢂSEM (mM)
a2
a2/PNMT
selectivity
KiꢂSEM (mM)
15
16
H
NO2
58ꢂ3
100ꢂ10
680ꢂ10
1.7
130
5.3ꢂ0.3
Table 4. Minimum distances between potential binding groups in the
superimposition of R- or S-15 and R-30a
Binding group
Distance
R-15 vs R-30
S-15 vs R-30
Oxygen lone pairs
Hydroxyl hydrogens
Hydroxyl oxygens
1.17 A
2.86 A
3.47 A
Oxygen lone pairs
Hydroxyl hydrogens
Hydroxyl oxygens
1.05 A
0.85 A
1.62A
aCompounds were superimposed using both ends of a 2A long normal
through the centroid of the aromatic ring and the end of the axial lone
pair (2.4 A) from the THIQ or THBA nitrogen and distances were
measured using the ‘‘Analyze: Measure Distance’’ menu option in
SYBYL.

G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
1961
Figure 1. Superimpositions of the enantiomers of 15 (green; a: R and b: S) over the more active (at PNMT) enantiomer of 30 (white; R). Compounds
were superimposed using both ends of a 2A long normal through the centroid of the aromatic ring and the end of the axial lone pair (2.4 A) from
the THIQ or THBA nitrogen. Hydroxyl oxygens are shown in red, hydroxyl hydrogens are in cyan, and lone pairs are in yellow. The hydrogens on
the carbon skeleton have been deleted for clarity.
selectivity ratios. Thus, THBA—and particularly
compound 3—would provide promising leads in the
development of a selective and CNS-active PNMT
inhibitor.
Infrared spectra were obtained on a Perkin–Elmer 1420
infrared spectrophotometer. Electron-impact mass
spectra (EIMS) were obtained on a Ribermag R10-10
mass spectrometer. The relative intensities of the mass
spectrum peaks are listed in parentheses. Flash chro-
matography17 was performed using silica gel 60 (230–
400 mesh) supplied by Universal Adsorbents, Atlanta,
Georgia. Preparative centrifugal thin layer chromato-
graphy (PCTLC) was performed on a Harrison model
7924 Chromatotron (Harrison Research, Palo Alto,
Experimental
All reagents and solvents were reagent grade or were
purified by standard methods before use. Melting points
were determined in open capillaries on a Thomas
Hoover melting point apparatus calibrated with known
compounds, but were otherwise uncorrected. Proton
nuclear magnetic resonance spectra (1H NMR) were
recorded on a Varian XL-300 or a GE QE-300 spectro-
meter with CDCl3 as the solvent, and chemical shifts are
reported in parts per million (ppm) relative to tetra-
methylsilane (TMS, 0.00 ppm). Carbon nuclear mag-
netic resonance spectra (13C NMR) were recorded on a
Varian XL-300 spectrometer with CDCl3 as the solvent,
and the chemical shifts are reported in ppm relative to
CDCl3 (77.0 ppm). NMR spectra of hydrochloride salts
were recorded in deuterated dimethylsulfoxide (DMSO-
d6) and the chemical shifts are reported relative to
.
CA) using Merck silica gel 60 PF254/CaSO4 0.5H2O
binder on 1, 2or 4 mm thickness plates. Analytical TLC
was performed by using silica gel with a fluorescent
indicator coated on 1ꢃ3 inch glass plates in 0.2mm
thickness (Whatman MKGF silica gel 200 mM). Bulb-
to-bulb distillations were carried out on a Kugelrohr
distillation apparatus (Aldrich Chemical Co., Milwau-
kee, WI), and oven temperatures were recorded. Com-
bustion analyses were performed on a Hewlett-Packard
Model 185B CHN Analyzer at the University of Kansas
by Dr. Tho Ngoc Nguyen.
Unless otherwise stated, all methanol (MeOH) and
ethanol (EtOH) used were anhydrous and were
prepared by distillation from magnesium. Hexanes
refer to the mixture of hexane isomers (bp 40–70 ꢁC).
Solvents were routinely distilled prior to use; anhydrous
1
DMSO (2.49 ppm for H and 39.5 ppm for 13C). Multi-
plicity abbreviations: s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet; bs, broad singlet; e, exchangeable.

1962
G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
tetrahydrofuran (THF) and ether (Et2O) were obtained
by distillation from sodium-benzophenone ketyl; dry
methylene chloride (CH2Cl2) was obtained by distilla-
tion from phosphorus pentoxide. n-Butyl lithium was
standardized by titration against 2,5-dimethoxybenzyl
alcohol. All reactions requiring anhydrous conditions or
an inert atmosphere were performed under a positive
nitrogen (N2) or argon (Ar) flow and all glassware was
oven-dried and/or flame-dried.
H-7), 8.18 (d, 1H, J=2.3 Hz, H-9), 4.15 (s, 2H, H-1),
3.29 (t, 2H, J=5.3 Hz, H-3), 3.14–3.11 (m, 2H, H-5),
1.90–1.81 (m, 2H, H-4), 1.76 (bs, e, 1H, NH); 13C NMR
(CDCl3) d 150.7, 148.0, 145.2, 143.5, 125.3, 117.5, 54.2
(C-1), 52.8 (C-3), 29.5 (C-5), 28.7 (C-4); EIMS m/z 238
(M++1, 5), 237 (M+, 5), 236 (6), 208 (43), 192 (20), 191
(M+ꢀNO2, 20), 190 (25), 144 (25), 115 (73), 89 (44), 84
(44), 63 (50), 49 (100).
The hydrochlꢁoride salt was isolated as fine yellow needles:
43.89; H, 4.42; N, 15.35; found: C, 43.55; H, 4.10; N,
14.99%.
.
mp 247–249 C. Anal. calcd for C10H11N3O4 HCl: C,
Amine hydrochloride or oxalate salts were prepared by
the addition of a solution of methanolic HCl (or oxalic
acid) to a methanolic solution of the amine, followed by
crystallization of the resulting salt from MeOH/Et2O.
8-Amino-2,3,4,5-tetrahydro-1H-2-benzazepine bisoxalate
.
(4 2C2H2O4). Compound 3 (4.5 g, 23 mmol) was dis-
S-Adenosyl-l-methionine was obtained from Sigma
Chemical Co. [methyl-3H]-S-Adenosyl-l-methionine
that was used in the radiochemical assay was purchased
from New England Nuclear Corp. (Boston, MA).
Bovine adrenal glands were obtained from Davis Meat
Processing (Overbrook, KS). [3H]Clonidine used in the
a2-adrenoceptor binding assay was purchased from
Amersham Corporation (Arlington Heights, IL).
solved in EtOH (50 mL) and concentrated HCl (5 mL)
was added. After the addition of PtO2 (50 mg), the pale
yellow solution was hydrogenated at 50 psi until there
was no further uptake of H2 (3 h). The reaction mixture
was filtered through Celite, concentrated on a rotary
evaporator and chilled in an ice-bath. The cold con-
centrated aqueous solution was made alkaline (pH
>10) with solid KOH and extracted with CH2Cl2
(thrice). The combined CHCl3 extracts were dried over
anhydrous Na2SO4 and evaporated to yield 4 (3.6 g,
The syntheses of compounds 9–16 have been reported
previously.8
95%) as a buff-colored solid: mp 65–75 ꢁC, H NMR
1
6,8-Dinitro- and 8-nitro-2,3,4,5-tetrahydro-1H-2-benza-
(CDCl3) d 6.91 (d, 1H, J=7.3 Hz, H-6), 6.44–6.41 (m,
2H, H-7 and H-9), 3.79 (s, 2H, H-1), 3.25–2.95 (m, bs,
5H, H-3, NH2 and NH, e), 2.82–2.78 (m, 2H, H-5),
1.66–1.61 (m, 2H, H-4); 13C NMR (CDCl3) d 144.3,
143.1, 132.4, 129.8, 115.5, 112.9, 54.8 (C-1), 53.2 (C-3),
34.9 (C-5), 31.0 (C-4).
3
.
.
zepine hydrochloride (17 HCl and 3 HCl). Compound 1
(5.82g, 39.6 mmol) was dissolved in cold concentrated
H2SO4 (20 mL) in an ice bath, and KNO3 (4.40 g,
43.5 mmol) was added in small portions over 1 h. The
ice bath was removed and the yellow–green reaction
mixture was allowed to warm to room temperature,
stirred for 12h, and carefully made alkaline (pH >10)
with concentrated NH4OH. The red–brown solution
obtained was extracted with CHCl3 (4ꢃ). The combined
CHCl3 extracts were washed with brine (once), dried
over anhydrous Na2SO4 and evaporated to yield a yel-
low solid (7.60 g). Purification by flash chromatography
(silica, CH2Cl2/MeOH/NH4OH, 250:17:1 as the eluent)
gave 3 (4.59 g, 60%) and dinitro compound 17 (0.64 g,
7%). Compound 3 was obtained as a pale yellow solid:
mp 60–61 ꢁC; IR (KBr) 3200 (NH), 2920, 1510 (NO2),
.
The bisoxalate salt (4 2C2H2O4) was isolated as a white
precipitate: mp 185–186 ꢁC; EIMS m/z 163 (M++1, 5),
162(M +, 26), 145 (32), 133 (35), 132 (36), 116 (28), 106
(16), 77 (16), 45 (100). Anal. calcd for
.
C10H14N2 2C2H2O4: C, 49.12; H, 5.30; N, 8.18; found:
C, 48.78; H, 5.20; N, 8.00%.
8-Bromo-2,3,4,5-tetrahydro-1H-2-benzazepine
hydro-
.
chloride (5 HCl). Amine 4 (3.20 g, 19.7 mmol) was
added to a mixture of ice-cold 48% HBr (9.6 mL) and
water (31.3 mL). To this stirred solution, sodium nitrite
(1.50 g, 21.7 mmol) in water (19 mL) was added drop-
wise. The reddish colored solution turned orange.
Excess HNO2 was destroyed by the addition of urea
(0.78 g) and a negative starch-iodide test was obtained.
This diazotized solution was added to a well-stirred,
warm (35 ꢁC) mixture of CuBr (8.48 g, 59.1 mmol),
48% HBr (20 mL) and water (50 mL). After addition of
the diazotized solution, the reaction mixture was
warmed to 75–80 ꢁC and stirred at that temperature for
1.5 h. The reaction mixture was allowed to stand over-
night and was cautiously made alkaline (pH>10)
with 50% KOH solution. The blue copper salts
were removed by filtration and the filtrate extracted
with CH2Cl2 (4ꢃ). The organic layers were com-
bined, dried over anhydrous Na2SO4 and evaporated to
yield a dark red oil (3.59 g). Bulb-to-bulb distillation
(105–110 ꢁC, 0.05 mm Hg) yielded compound 5 as a
colorless solid (3.36 g, 76%): mp 68–69 ꢁC; IR (KBr)
1
1330 (NO2), 1080, 740 cmꢀ1; H NMR (CDCl3) d 8.00–
7.98 (m, 2H, H-7 and H-9), 7.31–7.29 (m, 1H, H-6), 4.01
(s, 2H, H-1), 3.24 (t, 2H, J=4.9 Hz, H-3), 3.06–3.02(m,
2H, H-5), 1.77–1.74 (m, 2H, H-4), 1.61 (bs, e, 1H, NH);
13C NMR (CDCl3): d 150.8, 145.8, 144.2, 129.9, 122.8,
121.9, 54.4 (C-1), 53.2 (C-3), 35.9 (C-5), 29.9 (C-4);
EIMS m/z 193 (M++1, 18), 192(M +, 100), 177 (57),
145 (51), 131 (29), 116 (42), 115 (98), 103 (14), 91 (54),
77 (44), 63 (48), 51 (43), 43 (27).
.
The hydrochloride salt (3 HCl) was isolated as fluffy
white needles: mp >300 ꢁC. Anal. calcd for
.
C10H12N2O2 HCl: C, 52.52; H, 5.73; N, 12.25; found: C,
52.56; H, 6.10; N, 12.18%.
Compound 17 was crystallized as yellow needles from
EtOAc/hexanes: mp 111–112 ꢁC; IR (KBr) 3350 (NH),
1530 (NO2), 1340 (NO2), 1135, 1080, 910, 780,
1
735 cmꢀ1; H NMR (CDCl3) d 8.38 (d, 1H, J=2.3 Hz,

G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
1963
3200 (NH), 2990, 2910, 1480, 1140, 1110, 850, 810 cmꢀ1
;
dried over anhydrous Na2SO4 and evaporated to yield a
pale yellow oil (0.56 g). Bulb-to-bulb distillation (125–
135 ꢁC, 0.03 mm Hg) gave a colorless oil (0.43 g, 49%):
1H NMR (CDCl3) d 7.27–7.22 (m, 2H, ArH), 7.02–6.99
(m, 1H, ArH), 3.87 (s, 2H, H-1), 3.20–3.17 (m, 2H, H-
3), 2.90–2.86 (m, 2H, H-5), 1.72–1.60 (m, 3H, H-4 and
NH, e); 13C NMR (CDCl3) d 144.9, 141.8, 131.0, 130.8,
129.7, 119.3, 54.6 (C-1), 53.5 (C-3), 35.5 (C-5), 30.6 (C-
4).
mp 59–61 ꢁC; H NMR (CDCl3) d 7.10–7.00 (m, 3H,
1
ArH), 3.88 (s, 2H, H-1), 3.17 (t, 2H, J=5.3 Hz, H-3),
2.91–2.87 (m, 2H, H-5), 2.45 (s, 3H, SCH3), 1.69–1.62
(m, 3H, H-4 and NH, e); 13C NMR (CDCl3) d 143.4,
139.9, 135.2, 129.7, 126.9, 125.3, 54.9 (C-1), 53.5 (C-3),
35.5 (C-5), 30.9 (C-4), 16.1 (SCH3).
.
The hydrochloride salt (5 HCl) was isolated as colorless
plates: mp >300 ꢁC; EIMS m/z 228 (9), 227 (M++2,
56), 226 (27), 225 (M+, 57), 210 (18), 130 (19), 117 (65),
116 (53), 115 (100), 102(14), 89 (41), 77 (27), 63 (45), 51
The hydrochloride salt was isolated as fine colorless
needles: mp 268 ꢁC (dec); IR (KBr) 2950, 2800, 2730,
1575, 1490, 1440, 1425, 1075, 820 cmꢀ1; EIMS m/z 195
(M++2, 7), 194 (M++1, 24), 193 (M+, 100), 192
(M+ꢀ1, 19), 178 (M+ꢀCH3, 19), 176 (61), 164 (83),
149 (35), 146 (14), 134 (15), 129 (30), 117 (79), 116 (50),
115 (99), 103 (16), 91 (56), 77 (52), 45 (46). Anal. calcd
.
(34). Anal. calcd for C10H12BrN HCl: C, 45.74; H, 4.99;
N, 5.33; found: C, 45.85; H, 5.00; N, 5.10%.
8-Bromo-N-triphenylmethyl-2,3,4,5-tetrahydro-1H-2-ben-
zazepine (18). To a stirred solution of 5 (3.36 g,
14.9 mmol) in dry CH2Cl2 (40 mL), triethylamine
(1.65 g, 2.23 mL, 16.3 mmol) was added and the solution
was stirred in an ice bath. 4-Dimethylaminopyridine
(0.18 g, 1.5 mmol) and triphenylmethyl chloride (6.21 g,
22.3 mmol) were added in one portion and the reaction
mixture was stirred vigorously. After a few minutes a
copious precipitate of triethylammonium hydrochloride
was observed in the reaction mixture. The reaction was
stirred at room temperature for 18 h, quenched with 1 N
NaOH and extracted with CH2Cl2 (thrice). The com-
bined organic extracts were dried over anhydrous
Na2SO4 and evaporated to yield a yellow–orange solid
(10.1 g). The solid was passed through a silica plug using
CH2Cl2/hexanes/MeOH/NH4OH (150:450:10:1) as the
eluent to yield a colorless foamy solid (6.26 g, 90%): mp
145–150 ꢁC; IR (KBr) 2920, 1480, 1440, 950, 775, 745,
700 cmꢀ1; 1H NMR (CDCl3) d 7.51–7.43 (m, 6H, ArH),
7.30–7.13 (m, 11H, ArH), 7.04-7.02(m, 1H, Ar H), 3.45-
3.15 (m, 2H, H-1), 2.72-2.60 (m, 2H, H-3), 1.95–1.85 (m,
2H, H-5), 1.59–1.50 (m, 2H, H-4); EIMS m/z 469
(M++2, 0.2), 467 (M+, 0.2), 392 (M++2ꢀPh, 1), 390
(M+ꢀPh, 1), 244 (31), 243 (Ph3C+, 100), 185 (31), 84
(23), 77 (11), 49 (57). Anal. calcd for C29H26BrN: C,
74.36; H, 5.59; N, 2.99; found: C, 74.67; H, 6.00; N,
2.99%.
.
for C11H15NS HCl: C, 57.50; H, 7.02; N, 6.10; found: C,
57.40; H, 7.18; N, 6.40%.
8-Methylsulfonyl-2,3,4,5-tetrahydro-1H-2-benzazepine
.
hydrochloride (7 HCl). Trifluoroacetic acid (3 mL) was
added to compound 6 (0.295 g, 1.52 mmol) and the
mixture was stirred in an ice bath. Trifluoroperacetic
acid (8 N, 0.83 mL, 6.6 mequiv) was added in one por-
tion and stirred for 18 h at room temperature. The acids
were carefully removed under reduced pressure and
residual acid was removed by addition of benzene to the
residue followed by evaporation. The colorless oil
obtained was made alkaline (pH>10) with 3 N NaOH
and extracted with CHCl3 (thrice). The combined
CHCl3 extracts were washed with brine, dried over
anhydrous Na2SO4 and the solvent removed under
reduced pressure to yield a pale yellow solid (0.284 g).
Purification by PCTLC (silica gel, 4 mm) using CH2Cl2/
MeOH/NH4OH (250:17:1) as the eluent gave 7 as a pale
yellow solid (0.252 g, 74%): mp 119–121 ꢁC; IR (KBr)
3200 (NH), 2910, 1290 (SO2), 1140 (SO2), 1110, 1085,
1
960, 825, 770 cmꢀ1; H NMR (CDCl3) d 7.72–7.68 (m,
2H, H-9 and H-7), 7.34–7.32 (m, 1H, H-6), 4.00 (s, 2H,
H-1), 3.25–3.21 (m, 2H, H-3), 3.04–3.01 (m, 5H, H-5
and SO2CH3), 1.86 (s, e, 1H, NH), 1.77–1.70 (m, 2H, H-
4); 13C NMR (CDCl3) d 149.4, 144.0, 137.8, 130.0,
126.7, 126.0, 54.5 (C-1), 53.3 (C-3), 44.3 (SO2CH3), 35.9
(C-5), 29.8 (C-4).
8-Methylthio-2,3,4,5-tetrahydro-1H-2-benzazepine hydro-
.
chloride (6 HCl). In a flame dried three-neck round-
bottom flask equipped with a thermometer, magnetic
stirrer and a N2 inlet was placed 18 (2.1 g, 4.5 mmol) in
dry THF (20 mL). The solution was chilled to ꢀ78 ꢁC
and n-BuLi (2.3 M in hexanes, 2.3 mL, 5.3 mmol) was
added dropwise. A dark red solution was obtained and
was allowed to warm to ꢀ20 ꢁC over 30 min. The reac-
tion mixture was again chilled to ꢀ78 ꢁC and a solution
of methyl disulfide (0.53 g, 0.51 mL, 5.6 mmol) in dry
THF (3 mL) was added. The pale yellow reaction mix-
ture was allowed to warm to room temperature and
stirred overnight. The mixture was cooled in an ice bath
and acetone (8 mL) and concentrated HCl (4 mL) were
added. The colorless mixture was stirred for 12h and
the organic solvents were removed under reduced pres-
sure. The residue was diluted with water (30 mL) and
washed with CH2Cl2 (twice). The aqueous layer was
made alkaline (pH >10) with 6 N NaOH and extracted
with CH2Cl2 (4ꢃ). The combined CH2Cl2 extracts were
.
The hydrochloride salt (7 HCl) was isolated as fluffy
white needles: mp 286ꢀ288 ꢁC (dec); EIMS m/z 227
(M++2, 5), 226 (M++1, 17), 225 (M+, 64), 224
(M+ꢀ1, 41), 210 (M+ꢀCH3, 34), 145 (29), 131 (22),
118 (20), 117 (71), 116 (50), 115 (100), 103 (16), 102 (13),
91 (55), 77 (48), 63 (61), 42(38). Anal. calcd for
.
C11H15NO2S HCl: C, 50.47; H, 6.16; N, 5.35; found: C,
50.68; H, 6.40; N, 5.28%.
8-Aminosulfonyl-2,3,4,5-tetrahydro-1H-2-benzazepin-1-
one (20). Amide 198 (0.30 g, 1.9 mmol) was added to
ice-cold chlorosulfonic acid (3 mL) and the mixture was
allowed to warm to room temperature. After stirring for
6 h, the brown solution was poured over ice and extrac-
ted with EtOAc (thrice). The combined EtOAc extracts
were washed with 5% NaHCO3 (once) and brine (once),
dried over anhydrous Na2SO4 and the solvent removed

1964
G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
under reduced pressure to yield a yellow–red solid
(0.50 g) which was dissolved in acetonitrile (5 mL) and
concentrated NH4OH (5 mL) and heated to reflux for
2h. The solvent was removed under reduced pressure to
yield a yellow–red solid that was crystallized from
aqueous EtOH to yield a colorless solid (0.35 g, 78%):
mp 215–216 ꢁC (dec); IR (KBr) 3360 (NH2), 3290
(NH2), 3190 (NH), 1630 (CO), 1340 (SO2), 1170 (SO2)
counting. The mode of inhibition was ascertained to be
competitive in all cases reported in Tables 1–3 by
inspection of the 1/V versus 1/S plots of the data. All
assays were run in duplicate with 3 inhibitor concentra-
tions over a 5-fold range. Ki values were determined by
a hyperbolic fit of the data.
ꢀ2-Adrenoceptor radioligand binding assay. The radi-
oligand receptor binding was performed according to
the method of U0Prichard et al.12 Male Sprague–Dawley
rats were decapitated and the cortexes were dissected
out and homogenized in 20 volumes (w/v) of ice-cold
50 mM Tris/HCl buffer (pH 7.7 at 25 ꢁC). Homogenates
were centrifuged thrice for 10 min at 50,000ꢃg with
resuspension of the pellet in fresh buffer between spins.
The final pellet was homogenized in 200 volumes (w/v)
of ice-cold 50 mM Tris/HCl buffer (pH 7.7 at 25 ꢁC).
Incubation tubes containing [3H]clonidine (specific
activity ca. 19 mCi/mmol, final concentration 4.0 nM),
various concentrations of drugs, and an aliquot of
freshly resuspended tissue (800 mL) in a final volume of
1 mL were used. Tubes were incubated at 25 ꢁC for 30
min and the incubation was terminated by rapid filtra-
tion under vacuum through GF/B glass fiber filters. The
filters were rinsed with three 5 mL washes of ice-cold
50 mM Tris buffer (pH 7.7 at 25 ꢁC). The filters were
counted in vials containing premixed scintillation cocktail.
Non-specific binding was defined as the concentration of
bound ligand in the presence of 2 mM of phentolamine.
All assays were run in quadruplicate with 5 inhibitor
concentrations over a 16-fold range. IC50 values were
determined by a log-probit analysis of the data and Ki
values were determined by the equation Ki=IC50/
(1+[Clonidine]/KD), as all Hill coefficients were
approximately equal to 1.
1
1140, 905, 830, 800, 750 cmꢀ1; H NMR (DMSO-d6) d
8.27 (bs, e, 1H, NH), 7.97 (s, 1H, H-9), 7.84 (d, 1H,
J=7.8 Hz, H-7), 7.45–7.43 (m, 3H, H-6 and SO2NH2);
2.95–2.89 (m, 2H, H-3), 2.81–2.79 (t, 2H, J=6.8 Hz, H-
5), 1.94–1.89 (m, 2H, H-4); 13C NMR (DMSO-d6) d
170.6 (CO), 142.8, 141.9, 136.5, 129.4, 127.7, 125.6, 38.3
(C-3), 29.7, 29.6; EIMS m/z 241 (M++1, 17), 240 (M+,
78), 222 (12), 212 (18), 211 (25), 159 (13), 132 (21), 131
(100), 115 (13), 103 (38), 89 (13), 77 (42), 63 (35), 51
(35). Anal. calcd for C10H12N2O3S: C, 49.99; H, 5.03;
N, 11.66; found: C, 49.89; H, 4.80; N, 11.79%.
8-Aminosulfonyl-2,3,4,5-tetrahydro-1H-2-benzazepine
.
Hydrochloride (8 HCl). Amide 20 (0.50 g, 2.1 mmol)
.
was suspended in dry THF (10 mL) and BH3 THF (1M
solution in THF, 5 mL, 5.0 mmol) was added. The sus-
pension was heated to reflux under N2 for 24 h and the
resulting cloudy reaction mixture was cooled in an ice
bath. Excess BH3 was destroyed by the addition of
MeOH. Evaporation of the solvent gave a colorless
semisolid that was dissolved in MeOH (10 mL) and
concentrated HCl (2mL) and heated to reflux for 3 h.
The solvent was removed under reduced pressure to
yield a colorless solid, which was recrystallized (twice)
from EtOH acidified with few drops of concentrated
HCl to yield a colorless solid (0.40 g, 73%): mp 212–
214 ꢁC; IR (KBr) 3270 (NH2), 3010, 1560, 1310 (SO2),
1280, 1140 (SO2), 1115, 835, 660 cmꢀ1 1H NMR
,
(DMSO-d6) d 8.83 (bs, e, 2H, NH+2 ), 7.87 (s, 1H, H-9),
7.75 (d, 1H, J=7.8 Hz, H-7), 7.47 (d, 1H, J=7.8 Hz, H-
6), 7.40 (s, e, 2H, SO2NH2), 4.42(s, 2H, H-1), 3.37 (m,
2H, H-3), 3.10-3.00 (m, 2H, H-5), 1.90–1.80 (m, 2H, H-
4); 13C NMR (DMSO-d6) d 147.4, 142.4, 133.8, 130.0,
127.9, 126.4, 49.8, 49.7, 33.0, 24.6; EIMS m/z 227
(M++1, 14), 226 (M+, 29), 225 (M+ꢀ1, 19), 211 (16),
146 (7), 130 (10), 117 (31), 116 (24), 115 (46), 91 (21), 77
(13), 63 (11), 49 (100). Anal. calcd for
Molecular modeling studies. CLogP values were
calculated15 and molecular modeling was performed
using the SYBYL software package (version 6.6, Tripos
Associates, Inc., 1699 South Hanley Rd., St. Louis,
MO 63144, USA) on a Silicon Graphics O2work
station.
Acknowledgements
.
C10H14N2O2S HCl: C, 45.71; H, 5.75; N, 10.66; found:
C, 45.35; H, 5.86; N, 10.48%.
This research was supported by USPHS Grant HL
34193.
Radiochemical assay for PNMT activity. The assay used
in this study has been described elsewhere.10 Briefly, a
typical assay mixture consisted of 50 mL of 0.5 M phos-
phate buffer (pH 8.0), 25 mL of 10 mM unlabeled Ado-
Met, 5 mL of [methyl-3H]AdoMet, containing
approximately 3ꢃ105 dpm (specific activity approxi-
mately 15 Ci/mmol), 25 mL of substrate solution (phe-
nylethanolamine), 25 mL of inhibitor solution, 25 mL of
the enzyme preparation, and sufficient water to achieve
a final volume of 250 mL. After incubation for 30 min at
37 ꢁC, the reaction mixture was quenched by addition of
250 mL of 0.5 M borate buffer (pH 10.0) and was
extracted with 2mL of toluene/isoamyl alcohol (7:3). A
1 mL portion of the organic layer was removed, trans-
ferred to a scintillation vial and diluted with cocktail for
References and Notes
1. Taken in large part from the Ph.D. dissertation of Daha-
nukar, V. H., University of Kansas, 1994.
2. Fuller, R. W. Ann. Rev. Pharmacol. Toxicol. 1982, 22, 31.
3. Grunewald, G. L.; Dahanukar, V. H.; Ching, P.; Criscione,
K. R. J. Med. Chem. 1996, 18, 3539.
4. Grunewald, G. L.; Dahanukar, V. H.; Jalluri, R. K.; Cris-
cione, K. R. J. Med. Chem. 1999, 42, 118.
5. Grunewald, G. L.; Sall, D. J.; Monn, J. A. J. Med. Chem.
1988, 31, 824.
6. Grunewald, G. L.; Dahanukar, V. H.; Teoh, B.; Criscione,
K. R. J. Med. Chem. 1999, 42, 1982.

G. L. Grunewald et al. / Bioorg. Med. Chem. 9 (2001) 1957–1965
1965
7. Bondinell, W. E.; Pendleton, R. G. (Smithkline Corp.) Eur.
Pat. Appl. 002624, 1979; Chem. Abstr. 1980, 92, 22401h.
8. Grunewald, G. L.; Dahanukar, V. H. J. Heterocycl. Chem.
1994, 31, 1609.
9. Ackerman, K.; Horning, D. E.; Muchowski, J. M. Can. J.
Chem. 1972, 50, 3886.
10. Grunewald, G. L.; Borchardt, R. T.; Rafferty, M. F.;
Krass, P. Mol. Pharmacol. 1981, 20, 377.
11. Connett, R. J.; Kirshner, N. J. Biol. Chem. 1970, 245, 329.
12. U0Prichard, D. C.; Greenberg, D. A.; Snyder, S. H. Mol.
Pharmacol. 1977, 13, 454.
Sawyer, J.; Bondinell, W.; Intoccia, A. J. Pharmacol. Exp.
Ther. 1979, 208, 2 4.
14. Grunewald, G. L.; Caldwell, T. M.; Li, Q.; Slavica, M.;
Criscione, K. R.; Borchardt, R. T.; Wang, W. J. Med. Chem.
1999, 42, 3588.
15. CLogP values were calculated using the SYBL 6.6 imple-
mentation of the CLOGP algorithm. See also: Chou, J. T.;
Jurs, P. C. J. Chem. Inf. Sci. 1979, 19, 172.
16. SYBYL version 6.6, Tripos Associates, Inc.: St. Louis,
MO, 1999.
17. Still, W. C.; Mitra, A.; Kahn, M. J. Org. Chem. 1978, 43,
2923.
13. Pendleton, R. G.; Gessner, G.; Weiner, G.; Jenkins, B.;