N1-benzenesulfonylgramine and N 1-benzenesulfonylskatole: Novel 5-HT6 receptor ligand templates

Article abstract of DOI:10.1016/S0960-894X(03)00612-7

1-Benzenesulfonyl-5-methoxy-N,N-dimethyltryptamine (3; K_i=2.3 nM) is a 5-HT₆ receptor antagonist; removal of the 5-methoxy group (i.e., 6; K_i=4.1 nM) has little impact on receptor affinity. In the present study, it is shown that the aminomethyl portion of 6 can be shortened to gramine analogue 10a (K_i=3.1 nM); a related skatole derivative 11b (K_i=12 nM) also binds with high affinity indicating that the aminoethyl portion of the tryptamines is not required for binding. Compounds 10a and 11b represent members of novel classes of 5-HT₆ antagonists.

Full text of DOI:10.1016/S0960-894X(03)00612-7

Bioorganic & Medicinal Chemistry Letters 13 (2003) 3355–3359
N1-Benzenesulfonylgramine and N1-Benzenesulfonylskatole:
Novel 5-HT6 Receptor Ligand Templates
Manik R. Pullagurla,a Ma•gorzata Dukat,a Vincent Setola,b
Bryan Rothb,c and Richard A. Glennona,*
aDepartment of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298-0540, USA
bDepartment of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
cDepartments of Psychiatry and Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
Received 22 January 2003; accepted 25 April 2003
Abstract—1-Benzenesulfonyl-5-methoxy-N,N-dimethyltryptamine (3; Ki=2.3 nM) is a 5-HT6 receptor antagonist; removal of the
5-methoxy group (i.e., 6; Ki=4.1 nM) has little impact on receptor affinity. In the present study, it is shown that the aminomethyl
portion of 6 can be shortened to gramine analogue 10a (Ki=3.1 nM); a related skatole derivative 11b (Ki=12 nM) also binds with
high affinity indicating that the aminoethyl portion of the tryptamines is not required for binding. Compounds 10a and 11b repre-
sent members of novel classes of 5-HT6 antagonists.
# 2003 Elsevier Ltd. All rights reserved.
Rat and human 5-HT6 receptors were first identified
and cloned in the early to mid 1990s1ꢀ3 and represent
one of seven major families of serotonin receptors
(5-HT1-5-HT7).4 They are G-protein coupled receptors,
positively coupled to an adenylate cyclase second mes-
senger system, and are located primarily in the nucleus
accumbens, striatum, hippocampus, and olfactory
tubercle of the brain.5 The exact therapeutic significance
of 5-HT6 receptor ligands is still under investigation,
but the binding of various antipsychotics and anti-
depressants suggests their possible involvement in the
treatment of certain mental disorders.1,3,6 With the
development of the first 5-HT6 antagonists, additional
pharmacological actions have been implicated including
a role in cognition and convulsive disorders.7ꢀ9 Fur-
thermore, Slassi et al.8 have suggested that the
CNS-specific localization of 5-HT6 receptors should
make them attractive targets for drug development
because of the low likelihood that such agents would
have peripheral side effects.
Roche,10 and 2 (SB-271046) by SmithKline Beecham.11
Compounds (5-methoxy-N1-benzenesulfonyl-N,N-
3
dimethyltryptamine; MS-245) and 4 were reported from
our laboratory.12,13 Interestingly, although representing
independent discoveries, three of the four types of initial
5-HT6 antagonists possess a sulfonamide moiety. Fur-
thermore, 1 and 3 were serendipitous discoveries result-
ing from random screening, whereas 2 was derived from
structure–activity and pharmacokinetic optimization of
a lead initially identified from screening of the Smith-
Kline Beecham Compound Data Bank.11,12,14 Most
5-HT6 antagonists reported since that time are varia-
tions on these themes (e.g., sulfonamides, reversed sul-
fonamides, 2-substituted tryptamines).8,9
Because 1–3 each possesses an Aryl-N-SO2-Aryl’ frag-
ment, it was initially assumed that they might bind at
5-HT6 receptors in a similar manner.12 But, with the
recent discovery that reversed sulfonamide analogues of
2 retain 5-HT6 receptor affinity,15 this concept must now
be questioned. Furthermore, although the sulfonamido
moiety seems optimal, it has been shown that the aryl-
sulfonamido portion of 3 can be replaced by a benzoyl
or benzyl group with <10-fold decrease in affinity, and
that the –SO2– moiety of 3 can even be eliminated—
resulting in N1-(phenyl or substituted phenyl)-
tryptamines—with <25-fold reduction in affinity.16 It
now is not clear how 3 binds relative to 1 and 2. In fact,
The first four types of 5-HT6 antagonists described in
the literature were 1–4. Compounds 1 (1a, Ro 04-6790;
1b, Ro 63-0563) were reported by Hoffmann-La
*Corresponding author. Tel.: +1-804-828-8487; fax: +1-804-828-
7404; e-mail: glennon@hsc.vcu.edu
0960-894X/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0960-894X(03)00612-7

3356
M. R. Pullagurla et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3355–3359
Russell et al.17 have recently proposed an alternative
mode of overlap where the tryptamine amino group of 3
is associated with one of the piperazine nitrogen atoms
of 2. The purpose of the present investigation was to
examine more closely the terminal amine portion of 3,
and the aminoethyl group in particular, to determine
their influence on 5-HT6 receptor binding.
(Ki=2.9 and 19 nM, respectively). Apparently, the
5-methoxy group is not a major contributor to binding.
With respect to the terminal amine, the secondary
amine 7 (Ki=23 nM) binds with 10-fold lower affinity
than its parent, 3. The N,N-dimethyl substituents of 3
can be homologated to N,N-diethyl (8; Ki=6.2 nM)
with little effect on affinity; however, incorporation of a
bulkier benzyl group, as in 9 (Ki=43 nM), decreases
affinity by about 20-fold.
Binding Studies
5-HT6 receptor radioligand binding18 data are shown in
Table 1. Replacement of the 5-methoxy group of 3
(Ki=2.3 nM) with hydrogen has little impact on affinity
(i.e., 6; Ki=4.1 nM), and O-demethylation to the
hydroxy analogue 5 (Ki=28 nM) decreases affinity by
about 10-fold. While this paper was in preparation,
Russell et al.17 reported similar results for 6 and 5
The alkyl chain separating the terminal amine from the
indole nucleus was shortened by a methylene group.
Typically, such chain shortening in tryptamine analo-
gues is not well tolerated by serotonin receptors.19
However, in this instance, the chain-shortened analogue
10a20 (Ki=3.1ꢁ1.2 nM) retains high affinity as com-
pared to its tryptamine counterpart 6. The obvious
Table 1. Physicochemical and 5-HT6 receptor binding properties of benzenesulfonyltryptamine analogues20
X
R
R0
Z
Mp (ꢂC)
Recryst. solventa
% Yield
Empirical formula
Ki (nM)
(ꢁSEM)
3b
5
6
7
8
9
12
13
14
15
16
17
18
19
20
–OCH3
–OH
–H
–CH3
–CH3
–CH3
–CH3
–C2H5
–CH3
–CH3
–CH3
–C2H5
–C2H5
–CH3
–CH3
–C2H5
–C2H5
–CH3
–CH3
–CH3
–CH3
–H
–H
–H
–H
–H
–H
–NHAc
–NH2
–NHAc
–NH2
–NHAc
–NH2
–NHAc
–NH2
–NH2
—
—
ME
M
AM
M
M
M
P
M
—
78
22
83
54
33
43
78
32
88
33
90
27
80
20
—
C18H20N2O3S.C2H2O4
C18H20N2O2S.C2H2O4
C18H20N2O3S.C2H2O4
C21H26N2O3S.C2H2O4
C25H26N2O3S.C2H2O4
2.3
28
4.1
23
6.2
43
34
2.0
230
0.6
27
0.8
90
195–197
194–195
215
(6)
(0.3)
(6)
(0.2)
(15)
(6)
(0.1)
(80)
(0.2)
(11)
(0.4)
(30)
(0.2)
(1.0)
c
–OCH3
–OCH3
–OCH3
–OCH3
–OCH3
–OCH3
–OCH3
–H
–H
–H
–H
–OCH3
–H
–C2H5
–CH2Ph
–CH3
170
155–156
201–203
192–194
168–169
234–235
225
217–218
160–161
201–203
95–97
c
C21H25N3O4S.C2H2O4
C19H23N3O3S.2HCl
C23H29N3O4S.C2H2O4
C21H27N3O3S.HCl
–CH3
–C2H5
–C2H5
–CH3
M
AM
AM/E
M
ME
ME
C20H23N3O3S.C2H2O4
C18H21N3O2S.2HCl
–CH3
c
–C2H5
–C2H5
–CH2Ph
C22H27N3O3S.C2H2O4
C20H25N3O2S.2HCl
C25H27N3O3S.2HCl
0.6
3.0
aRecrystallization solvents: M=MeOH, AM=aqueous MeOH; ME=MeOH/anhydrous Et2O; P=nPrOH.
bBinding data for compound 3 was previously reported.12
cCompounds 6 and 18 crystallized with 0.5 mol H2O.

M. R. Pullagurla et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3355–3359
3357
question at this point is whether or not this amine is
even required for binding. Removal of the amine of 10a
would result in skatole analogue 11a, a compound that
lacks aqueous solubility.21 Hence, in order to examine
the need for an aminoalkyl group at the indole 3-posi-
tion, it was necessary to locate a position on the mole-
cule that would tolerate a solubilizing group. An amino
group was selected because a water-soluble salt could be
formed. It was already known from earlier studies that
both electron donating and electron withdrawing sub-
stituents are tolerated in the benzenesulfonyl ring of 3;
depending upon the specific substituent, the affinity of
the resulting compound is either slightly enhanced or
slightly decreased.12 Consequently, we prepared and
examined several aryl amine derivatives of 3, 6, and 8 to
determine if the amine would be tolerated. The corre-
sponding acetamido analogues were used as controls.
HEK cells, or to antagonize 5-HT-induced cAMP pro-
duction.22 Both compounds failed to behave as agonists,
but both antagonized the actions of 5-HT (data not
shown). Calculated IC50 values for the inhibition of
5-HT-stimulated cAMP production in HEK-5-HT6 cells
by 10a and 11b were 880 (ꢁ35) and 320 (ꢁ10) nM,
respectively. Schild analysis for 11b provided a pA2 of
7.0 (ꢁ0.2). Evidently, both compounds behave as
5-HT6 antagonists.
Summary
The present investigation demonstrates that the amino-
alkyl portion of N1-benzenesulfonyltryptamine is,
unexpectedly, not a requirement for 5-HT6 receptor
binding. N1-Benzenesulfonylgramines such as 10a and
10b (Ki=3.1 and 6.9 nM, respectively), derivatives of 3
(more specifically, derivatives of 6; Ki=4.1 nM) in
which the N,N-dimethylaminoethyl portion of the
molecule was shortened to an N,N-dimethylamino-
methyl group, retain affinity. Even more interesting is
that the N,N-dimethylamine portion of 10b could be
eliminated (11b; Ki=12 nM). Both 10a and 11b behaved as
antagonists of 5-HT-induced cAMP accumulation. These
studies, then, extend the structure–affinity and structure–
activity relationships of the N1-benzenesulfonyl-
tryptamines as 5-HT6 antagonists and identified two novel
classes of 5-HT6 antagonists: N1-benzenesulfonylgramines
and N1-benzenesulfonylskatoles. Furthermore, the affi-
nities of these novel analogues question the manner in
which they interact at 5-HT6 receptors relative to 2; that
is, if the amino group of 3-type compounds is not
required for binding, it seems unlikely that this amino
group must mimic one of the piperazine nitrogen atoms
of 2. Additional investigations with these classes of
compounds are currently underway.
Compound 13 (Ki=2.0 nM), the 40-amino analogue of
3, binds with the same affinity as its parent, 3. Likewise,
the affinities of amino analogues 15, 17, and 19 (Ki=0.6,
0.8, and 0.6 nM, respectively) are also quite high and
indicate that the amino group is tolerated at this posi-
tion. In compound 20 (Ki=3.0 nM), the presence of the
amino group actually increases affinity by nearly 15-fold
relative to its parent, 9. Furthermore, the affinity of 17
and 19 again indicate that the presence of a 5-methoxy
group is not required for binding. The lower affinities of
the corresponding acetamido derivatives 12, 14, 16, and
18 show that affinity is not directly related simply to the
presence of an NH substituent on the aryl ring. As a
further test of the tolerance of the para amino sub-
stituent, compound 10b20 was examined. The affinity of
10b (Ki=6.9ꢁ0.3 nM) was similar to that of 10a.
Acknowledgements
This work was supported in part by NIMH grant
MH-60599. Dr. Jagadeesh B. Rangisetty is gratefully
acknowledged for his assistance in the preparation of
compound 5.
References and Notes
On the basis that a para amino group is tolerated by
5-HT6 receptors, compound 11b was prepared and
examined. Compound 11b (Ki=12ꢁ9 nM) retains affi-
nity for 5-HT6 receptors. Even though its affinity is
about 3-fold lower than tryptamine derivative 6, it, like
10, represents a novel type of 5-HT6 receptor ligand.
1. Monsma, F. J.; Shen, Y.; Ward, R. P.; Hamblin, M. W.;
Sibley, D. R. Mol. Pharmacol. 1993, 43, 320.
2. Ruat, M.; Traiffort, E.; Arrang, J.-M.; Tardivel-Lacombe,
J.; Diaz, J.; Leurs, R.; Schwartz, J-C. Biochem. Biophys. Acta
1993, 193, 268.
3. Kohen, R.; Metcalf, M. A.; Khan, N.; Druck, T.; Huebner,
K.; Lachowiwicz, J. E.; Meltzer, H. Y.; Sibley, D. R.; Roth,
B. L.; Hamblin, M. W. J. Neurochem. 1996, 66, 47.
4. Hoyer, D.; Hannon, J. P.; Martin, G. R. Pharmacol. Bio-
chem. Behav. 2002, 71, 533.
Functional Studies
5. Ward, R. P.; Hamblin, M. W.; Lachowicz, J. E.; Hoffman,
B. J.; Sibley, D. R.; Dorsa, D. M. Neuroscience 1995, 64, 1105.
6. Roth, B. L.; Craigo, S. C.; Choudhary, M. S.; Uluer, A.;
Monsma, F. J.; Shen, Y.; Meltzer, H. Y.; Sibley, D. R.
J. Pharmacol. Exp. Ther. 1994, 268, 1403.
Benzenesulfonylgramine (1-BSG; 10a) and the amino
benzenesulfonylskatole derivative 11b (AminoBSK)
were examined for functional activity by measuring
their ability to either stimulate cAMP accumulation in

3358
M. R. Pullagurla et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3355–3359
7. Sleight, A. J.; Boess, F. G.; Bourson, A.; Sibley, D. R.;
Monsma, F. J. Drug News Perspect. 1997, 10, 214.
8. Slassi, A.; Isaac, M.; O’Brien, A. Expert Opin. Ther. Pat.
2002, 12, 513.
9. Russell, M. G. N.; Dias, R. Curr. Top. Med. Chem. 2002, 2,
643.
10. Sleight, A. J.; Boess, F. G.; Bos, M.; Levet-Trafit, B.;
Riemer, C.; Bourson, A. Br. J. Pharmacol. 1998, 124, 556.
11. Bromidge, S. M.; Brown, A. M.; Clarke, S. E.; Dodgson,
K.; Gager, T.; Grassam, H. L.; Jeffrey, P. M.; Joiner, G. F.;
King, F. D.; Middlemiss, D. N.; Moss, S. F.; Newman, H.;
Riley, G.; Routledge, C.; Wyman, P. J. Med. Chem. 1999, 42,
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12. Tsai, Y.; Dukat, M.; Slassi, A.; MacLean, N.; Demchy-
shyn, L.; Savage, J. E.; Roth, B. L.; Hufeisen, S.; Lee, M.;
Glennon, R. A. Bioorg. Med. Chem. Lett. 2000, 10, 2295.
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Roth, B. L.; Savage, J. E.; McBride, A.; Rauser, L.; Hufeisen,
S.; Lee, D. K. H. J. Med. Chem. 2000, 43, 1011.
of the H2 gas ceased. The resultant mass was dissolved in
anhydrous DMF (7 mL) and benzenesulfonyl chloride (0.56 g,
3.15 mmol) in anhydrous DMF (3 mL) was added in a drop-
wise manner at 0 ꢂC. The reaction mixture was allowed to stir
at room temperature overnight. At 0 ꢂC ice was added to the
reaction mixture to decompose the excess NaH followed by
H2O (15 mL); the crude mixture was dissolved in CH2Cl2 (30
mL) and washed with H2O (4ꢃ50 mL). The organic portion
was dried (MgSO4) and solvent was removed under reduced
pressure. The residue was purified by column chromatography
on silica gel (CH2Cl2/MeOH; 10:1) to give 0.21 g (23%) of an
oil. 1H NMR (CD3OD) d 2.65 (s, 6H, 2CH3), 4.27 (s, 2H,
CH2), 7.15 (dd, J=7.6 Hz, J=7.7 Hz, 1H, CH), 7.23 (dd,
J=7.6 Hz, J=7.9 Hz, 1H, CH), 7.31 (s, 1H, CH), 7.35 (d,
J=7.9 Hz, 1H, CH), 7.41–7.47 (m, 1H, CH), 7.55 (d, J=7.7
Hz, 1H, CH), 7.77–7.84 (m, 4H, 4CH). An oxalate salt was
prepared in anhydrous MeOH and recrystallized from MeOH/
ꢂ
.
Et2O: mp 198 C. Anal. calcd for (C17H18N2O2S C2H2O4) C,
H, N. 1-(4-Aminobenzenesulfonyl)-3-(N,N-dimethylamino-
methyl)indole hydrochloride (10b). A mixture of gramine (1.00
g, 5.73 mmol) and 60% NaH (0.26 g, 6.32 mmol) was heated
at reflux in DMF (25 mL) under N2 for 2 h. N-Acetylsulfanilyl
chloride (1.60 g, 6.88 mmol) in DMF (5 mL) was added in a
dropwise manner at 0 ꢂC, and the reaction mixture was
allowed to stir at room temperature overnight. The reaction
mixture was extracted with CH2Cl2 (2ꢃ50 mL); the combined
CH2Cl2 fraction was washed with H2O (4ꢃ50 mL) and the
organic portion was dried (MgSO4) and solvent was removed
under reduced pressure. The residue was purified by column
chromatography on silica gel (CH2Cl2/MeOH; 19:1) to give
1.10 g (52%) of a white solid: mp 65–67 ꢂC. Hydrochloric acid
(36%; 5 mL) was added to a solution of the solid acetamide
(0.50 g, 1.35 mmol) in absolute EtOH (25 mL) and heated at
reflux for 2 h. The reaction mixture was cooled to 0 ꢂC, 40%
NaOH solution was added to pH 12, and the mixture was
extracted with CH2Cl2 (3ꢃ50 mL). The combined organic
portion was dried (Na2SO4) and solvent was removed under
reduced pressure to give 0.40 g (90%) of 10b as the free base.
1H NMR (DMSO-d6) d 2.72 (d, J=4.2 Hz, 6H, 2CH3), 3.53
(bs, 2H, NH2), 4.42 (d, J=4.2 Hz, 2H, CH2), 6.55 (d, J=8.9
Hz, 2H, 2CH), 7.31 (dd, J=7.5 Hz, J=7.7 Hz, 1H, CH), 7.38
(dd, J=7.5 Hz, J=7.8 Hz 1H, CH), 7.60 (d, J=8.9 Hz, 2H,
2CH), 7.84 (d, J=7.8 Hz, 1H, CH), 7.88 (d, J=7.7 Hz, 1H,
CH), 8.05 (s, 1H, CH). The HCl salt was prepared in anhy-
drous MeOH and recrystallized from MeOH/Et2O: mp 215-
14. Bos, M.; Sleight, A. J.; Godel, T.; Martin, J. R.; Riemer,
C.; Stadler, H. Eur. J. Med. Chem. 2001, 36, 165.
15. Bromidge, S. M.; Clarke, S. E.; Gager, T.; Griffith, K.;
Jeffrey, P.; Jennings, A. J.; Joiner, G. F.; King, F. D.; Lovell,
P. J.; Moss, S. F.; Newman, H.; Riley, G.; Rogers, D.; Rou-
tledge, C.; Serafinowska, H.; Smith, D. R. Bioorg. Med. Chem.
Lett. 2001, 11, 55.
16. Lee, M.; Rangisetty, J. B.; Dukat, M.; Slassi, A.;
MacLean, N.; Lee, D. K. H.; Glennon, R. A. Med. Chem. Res.
2000, 10, 230.
17. Russell, M. G.; Baker, R. J.; Barden, L.; Beer, M. S.;
Bristow, L.; Broughton, H. B.; Knowles, M.; McAllister, G.;
Patel, S.; Castro, J. L. J. Med. Chem. 2001, 44, 3881.
18. Radioligand binding assay. The h5-HT6 radioligand
binding assays were performed as previously described.3,6 In
brief, h5-HT6 cDNA was transiently expressed in COS-7 cells
using the DEAE-dextran technique.6 Seventy-two hours after
transfection, cells were harvested by scraping and centrifuga-
tion from medium containing 10% dialyzed fetal calf serum.
Cells were then washed by centrifugation and resuspension
once in phosphate buffered saline (pH 7.40; PBS) and then
frozen as tight pellets at ꢀ80 ꢂC until use. Binding assays were
performed at room temperature for 90 min in binding buffer
(50 mM Tris–Cl, 10 mM MgCl2, 0.1 mM EDTA, pH 7.40)
with [3H]LSD (1 nM final concentration) using 10 mM cloza-
pine for non-specific binding. Various concentrations of unla-
beled test agent (1 to 10,000 nM) were used for Ki
determinations with Ki values calculated using the LIGAND
program.23 Specific binding represented 80–90% of total
binding. Ki values are the result of triplicate determinations.
19. Glennon, R. A.; Dukat, M. In Foye’s Textbook of Medi-
cinal Chemistry, Williams, D. A., Lemke, T., Eds.; Williams
and Wilkins: Baltimore, 2002; p 315.
20. Synthesis: Melting points (uncorrected) were obtained
with a Thomas Hoover apparatus. 1H NMR spectra were
recorded with a Varian EM-390 spectrometer, and peak posi-
tions are given in parts per million (d) downfield from tetra-
methylsilane as internal standard. Microanalyses were
performed by Atlantic Microlab (GA) for the indicated ele-
ments, and the results are within 0.4% of theory. Reactions
and product mixtures were routinely monitored by thin-layer
chromatography on silica gel precoated F254 Merck plates.
The free base of compound 10a was reported earlier by a dif-
ferent method of synthesis.21 Compounds in Table 1 were
prepared by a procedure similar to that employed for the
synthesis of 10b using the appropriate tryptamine derivative in
place of gramine. 1-Benzenesulfonyl-3-(N,N-dimethylamino-
methyl)indole oxalate (1-benzenesulfonylgramine; 10a). A mix-
ture of gramine (0.50 g, 2.87 mmol) and 60% NaH (0.13 g,
3.16 mmol) was heated at 130 ꢂC under N2 until the evolution
ꢂ
.
217 C. Anal. calcd for (C17H19N3O2S HCl) C, H, N. 1-(4-
Aminobenzenesulfonyl)-3-methylindole hydrochloride (1-[(4-
amino)benzenesulfonyl]skatole; 11b). A mixture of 3-methy-
lindole (0.50 g, 3.81 mmol) and 60% NaH (0.24 g, 6.00 mmol)
was heated at 110 ꢂC under N2 until the evolution of the H2
gas ceased. At 0 ꢂC, anhydrous DMF (7 mL) was added with
stirring followed by the dropwise addition of 4-nitrobenzene-
sulfonyl chloride (0.93 g, 4.19 mmol) in DMF (3 mL). The
reaction mixture was allowed to stir at room temperature
overnight. Ice and then H2O (25 mL) were added at 0 ꢂC to
decompose excess NaH. The crude product was dissolved in
CH2Cl2 (50 mL) and washed with H2O (4ꢃ50 mL). The
organic portion was dried (MgSO4) and solvent was removed
under reduced pressure. The residue was purified by column
chromatography on silica gel (petroleum ether/EtOAc; 19:1)
to give 0.22 g (18%) of a solid, mp 173 ꢂC, after recrystalliza-
tion from acetone/petroleum ether. Raney nickel in MeOH
(ꢄ0.8 g) was added to a methanolic (20 mL) solution of this
material (0.20 g, 0.632 mmol) in a Parr bottle, and the reaction
mixture was flushed several times with H2 and then main-
tained under H2 at a delivery pressure of 12 psi for 4 h. Cata-
lyst was removed by filtration and the filtrate was
concentrated under reduced pressure to give 0.17 g (59%) of a
solid. 1H NMR (CD3OD) d 2.03 (d, J=1.4 Hz, 3H, CH3),

M. R. Pullagurla et al. / Bioorg. Med. Chem. Lett. 13 (2003) 3355–3359
3359
7.00-7.14 (m, 3H, 3CH), 7.09 (d, J=8.8 Hz, 2H, 2CH), 7.19
(d, J=1.4 Hz, 1H, CH), 7.27 (d, J=7.0 Hz, 1H, CH), 7.74 (d,
J=8.8 Hz, 2H, 2CH). The HCl salt was prepared in CH2Cl2:
mp 195-196 C. Anal. calcd for (C15H14N2O2S HCl) C, H, N.
21. Hino, T.; Nakamura, T.; Nakagawa, M. Chem. Pharm.
Bull. 1975, 23, 2990.
22. cAMP accumulation assay: Increases in cytosolic cAMP
levels were measured as previously described in: Roth, B. L.;
Baner, K.; Westkaemper, R.; Siebert, D.; Rice, K. C.; Ernsberger,
P.; Rothman, R. B. Proc. Nat. Acad. Sci. U.S.A. 2002, 98, 7331.
23. Munson, P. J.; Rodbard, D. Analytical Biochem. 1980,
107, 220.
ꢂ
.