Synthesis of 5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3, 4-tetrahydropyrimidine oxalate salts and their evaluation as muscarinic receptor agonists

Article abstract of DOI:10.1002/ardp.200300730

The synthesis and biological test of 5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3, 4-tetrahydropyrimidine oxalate salts 7 as muscarinic receptor agonists are described. The key intermediate 4 was obtained by a modified Strecker reaction and cyclization, and the 3-methyl-1,2,3,4-tetrahydropyrimidines were obtained by subsequent substitution, quarternization, and reduction. The final products 7 were obtained as oxalic acid salts. The prepared compounds were examined in vitro for their binding affinities to the cloned human muscarinic receptor by the [³H]-NMS binding assay.

Full text of DOI:10.1002/ardp.200300730

230 Jung et al.
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
Myung Hee Junga,
Jewn-Giew Parkb,
Woo-Kyu Parka
Synthesis of
5-(4-Alkylsulfanyl-[1,2,5]Thiadiazol-3-yl)-
3-Methyl-1,2,3,4-Tetrahydropyrimidine Oxalate Salts
and their Evaluation as Muscarinic Receptor
Agonists
a
Korea Research Institute of
Chemical Technology,
Yusong, Taejon, Korea
Mayo Cancer Center,
b
The synthesis and biological test of 5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-yl)-3-me-
thyl-1,2,3,4-tetrahydropyrimidine oxalate salts 7 as muscarinic receptor agonists
are described.The key intermediate 4 was obtained by a modified Strecker reaction
and cyclization, and the 3-methyl-1,2,3,4-tetrahydropyrimidines were obtained by
subsequent substitution, quarternization, and reduction.The final products 7 were
obtained as oxalic acid salts.The prepared compounds were examined in vitro for
their binding affinities to the cloned human muscarinic receptor by the [3H]-NMS
binding assay.
Department of
Pharmacology, Mayo Clinic,
Rochester, MN, USA
Keywords: Muscarinic receptor agonists; 1,2,3,4-tetrahydropyrimidine; Alz-
heimer’s disease; Xanomeline
Received: September 27, 2002, Accepted: January 13, 2003 [FP730]
DOI 10.1002/ardp.200300730
prove the pharmacological and pharmacokinetic proper-
ties towards a clinically meaningful profile have led to the
Introduction
Recent work on Alzheimer’s disease (AD) has focused
on the development of M1-selective agonists [1, 2]. M1
muscarinic receptors play a role in memory function [3,
4] and stimulate phosphoinositide (PI) turnover in the
mammalian forebrain [5]. An M1 agonist is expected to
bind selectively to M1 muscarinic receptors and stimu-
late PI turnover in the hippocampus [6].
emergence of milameline (Chart 1) [9]. On the other
hand, xanomeline [10], in which 4-hexyloxy-[1,2,5]-
thiadiazole ring replaced the methyl ester of arecoline
and milameline, in which the alkoxyimino group replaced
the methyl ester, has been reported as a potent function-
al M1 selective muscarinic agonist (Chart 1).
Chart 1. Muscarinic agonists.
The naturally occuring agonist arecoline (Chart 1) had
been used for AD patients in the early clinical trial [7, 8].
However, arecoline has several major drawbacks includ-
ing low efficacy, lack of subtype selectivity and poor met-
abolic stability.Continued researches in the efforts to im-
We have reported the synthesis and biological activities
of 3-methyl-1,2,3,4-tetrahydropyrimidines bioisosteric
congeners as muscarinic receptor agonists of the tet-
rahydropyridine derivatives (Chart 2) [11, 12], milame-
line and xanomeline.
Herein, we describe the synthesis of alkylsulfanyl series
of bioisosteric congeners of xanomeline.
Correspondence:Myung Hee Jung, Korea Research Institute
of ChemicalTechnology, P.O.Box 107,Yusong,Taejon 305-600,
Korea. Phone:+82 42 860-7129, Fax:+82 42 861-1291, email:
mhjung@krict.re.kr.
© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0365-6233/04–05/0230 $ 17.50+.50/0

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
Methyl-1,2,3,4-Tetrahydropyrimidine Oxalate Salts 231
Synthesis
As depicted in Scheme 1, the key intermediate, 5-(4-
chloro-[1,2,5]thiadiazole-3-yl)pyrimidine4was prepared
as described in our previous paper [12].The starting ma-
terial, 5-pyrimidinecarboxaldehyde 1 was synthesized
from 4,6-dihydroxypyrimidine according to the known
procedure [13]. The resultant 4 was treated with KCN/
Chart 2. Bioisosteres of milameline and xanomeline.
Scheme 1

232 Jung et al.
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
AcOH to give the cyanohydrin 2 and then subsequent
treatment with NH4Cl/NH4OH in hot acetonitrile yielded
the aminonitrile 3. The one-pot Strecker conditions [14]
resulted in only very low yield of 3, but the thiadiazole 4
was obtained in high yield by treating 3 with sulfur mono-
chloride in DMF. To introduce the requisite alkylsulfanyl
groups, compound 4 was first reacted with sodium hy-
drosulfide hydrate and then followed by appropriate alkyl
halides in the presence of potassium carbonate to give
5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-yl)pyrimidine 5 in
47–73% yields. Compound 5 and an excess amount of
methyl iodide in boiling acetone for about 48 h afforded
the 3-quarternized pyrimidine salts 6 in quantitative
yields.The sodium borohydride reduction of 6 in metha-
nol at low temperature furnished 5-(4-alkylsulfanyl-
[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3,4-tetrahydropyri-
midine as the sole product.To enhance their stability and
purity, the product was further treated with oxalic acid in
methanol to give the oxalate salts 7. The structure of 7
can be deduced from X-ray crystallographic data of pyri-
midinylbenzoxazole which was previously obtained via
identical chemical pathway [15]. 1H-NMR spectra of the
final compound 7 showed singlets at 7.52–7.63 ppm cor-
responding to the C6-H, and the signals of the two pro-
tons at C4 were observed at 3.92–4.02 ppm as singlets.
values for [3H]-NMS and [3H]-Oxo-M of the compounds.
The affinity values of other M1 agonists are also present-
ed for comparison. Most 3-methyl-1,2,3,4-tetrahydropy-
rimidines, 7a–7i, synthesized asbioisosteric congeners
of tetrahydropyridine derivatives, showed higher binding
affinities for h-M1 with respect to those of arecoline and
milameline, but still much lower affinities to that of
xanomeline.There was a rank order among compounds
prepared and tested in binding affinity for h-M1 depend-
ing on the length of the alkyl substituent, i.e. compound
with longer chain showed higher affinity (7f > 7e > 7c >
7a).Compounds with benzyl substituent, 7g, 7hand7i,
showed similar affinity to h-M1.
Acknowledgement
We wish to thank the Korea Ministry of Science and
Technology (KK-0205-B0) for financial grants.
Experimental
Melting points were determined on a Thomas-Hoover appara-
tus and are uncorrected. Infrared spectra were recorded on a
Mattson Genesis II FTIR.Nuclear magnetic resonance spectra
were measured on a Brucker AM-300. Mass spectra were de-
termined on JEOL JMS-DX 303 Mass Spectrometer JEOL
JMA-DA 5000 mass data system focusing high resolution mass
spectrometers.Although the syntheses of compounds 2, 3, and
4 have been reported [12], the procedures were written herein
again for convenience.
Results and discussion
Binding affinities to the M1 receptor of the prepared com-
pounds were sought by their ability to displace [3H]-NMS
from the cloned human M1 receptor (h-M1) expressed in
CHO cells.Table 1 shows the percentages of inhibition of
[3H]-NMS binding to h-M1 at 100 µM, and the IC50
Preparation of Hydroxy(pyrimidin-5-yl)acetonitrile (2)
KCN 8.14 g (125.00 mmol) in 50 ml water was cooled to 5°C
then to this was added portions of 5-pyrimidinecarboxaldehyde
Table 1. Inhibitory effects of 3-methyl-1,2,3,4-tetrahydropyrimidines on [3H]-NMS and [3H]-Oxo-M binding.
Compounds
[3H]-NMS
IC50 (µM)*
[3H]-Oxo-M
IC50 (µM)*
Ratio
[3H]-NMS/[3H]-Oxo-M
7a
7b
7c
7d
7e
7f
7g
7h
7i
46.60 6.7
8.35 0.8
2.65 0.2
5.62 0.7
1.76 0.4
0.50 0.1
0.73 0.1
2.18 0.4
1.84 0.4
0.13 0.03
17.42 2.2
65.10 5.4
0.058 0.005
0.038 0.006
0.007 0.001
0.012 0.002
0.048 0.008
0.015 0.004
0.064 0.01
0.185 0.03
0.194 0.02
0.013 0.004
0.072 0.01
803.4
219.7
378.6
468.3
36.7
33.3
11.4
11.8
9.5
xanomeline
milameline
arecoline
10.0
241.9
2170.0
0.03
0.003
* Data represent the mean S.E.M from three assays each performed in duplicate.

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
Methyl-1,2,3,4-Tetrahydropyrimidine Oxalate Salts 233
5.40 g (50.00 mmol) maintaining the temperature below 10°C.
When all of the aldehyde had been added, 7.16 ml (125.00
mmol) acetic acid was added dropwise at a temperature
below10°C. After stirring for 2 h at room temperature the reac-
tion was cooled back to 5°C, then the precipitates were collect-
ed by filtration.The filter cake was washed briefly with cold wa-
ter, then dried under vacuum.Further purification by flash chro-
matography on silica gel (EtOAc) gave 4.55 g (67%) of the title
compound as a white powder.
5a:yield 47%;mp 143–145°C;IR (KBr) νmax:3080, 2925, 1405
cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.33 (s, 2H, C4-H, C6-H),
9.30 (s, 1H, C2-H), 2.80 (s, 3H, SCH3); 13C NMR (75 MHz,
CDCl3) δ:158.3 (C2), 157.4 (C3Ј), 155.8 (C4, C6), 151.7 (C4Ј),
126.5 (C5), 15.7 (SCH3);Anal.calcd.for C7H6N4S2:C, 39.99;H,
2.88; N, 26.65; S, 30.49. Found: C, 40.22; H, 2.72; N, 26.75; S,
30.54.
5b: yield 71%; mp 69–71°C; IR (KBr) νmax: 3050, 1590, 1550,
1460, 1180 cm–1;1H NMR (300 MHz, CDCl3) δ:9.33 (s, 2H, C4-
H, C6-H), 9.30 (s, 1H, C2-H), 3.37 (q, 2H, J = 7.4 Hz, SCH2),
1.48 (t, 3H, J = 7.4 Hz, CH3);13C NMR(75 MHz, CDCl3) δ:158.8
(C2), 156.8 (C3Ј), 155.9 (C4, C6), 152.1 (C4Ј), 126.5 (C5), 27.6
mp 142–144°C; IR (KBr) νmax: 3020 (OH), 2800, 1560, 1410
cm–1; 1H NMR (300 MHz, acetone-d6) δ: 9.23 (s, 1H, C2-H),
8.99 (s, 2H, C4-H, C6-H), 6.59 (br s, 1H, OH), 6.06 (s, CHCN);
13C NMR (75 MHz, acetone-d6) δ: 159.6 (C2), 155.9 (C4, C6),
131.7 (C5), 119.1 (CN), 59.7 (CCN);C6H5N3O (135.0433), MS:
m/z = 135.0432.
(SCH2), 14.3 (CH3); C8H8N4S2 (224.0190), MS: m/z
=
224.0191.
5c: yield 64%; mp 63–65°C; IR (KBr) νmax: 3060, 3010, 1560,
1430 cm–1;1H NMR (200 MHz, CDCl3) δ:9.32 (s, 2H, C4-H, C6-
H), 9.30 (s, 1H, C2-H), 6.00 (m, 1H, CH=CH2), 5.43 (dd, 1H,
J = 17.0, 1.0 Hz, C=CHtrans), 5.31 (dd 1H, J = 10.0, 1.0 Hz,
C=CHcis), 4.01 (d, 2H, OCH2); 13C NMR (75 MHz, CDCl3) δ:
158.3 (C2), 156.0 (C4, C6), 155.9 (C3Ј), 152.2 (C4Ј), 132.0
(CH=CH2), 126.5 (C5), 119.4 (CH=CH2), 35.9 (SCH2);
C9H8N4S2 (236.0190), MS: m/z = 236.0193.
Preparation of amino(pyrimidin-5-yl)acetonitrile (3)
To a stirred solution of 1.35 g (10.00 mmol) hydroxy-pyrimidin-
5-yl-acetonitrile and 2.67 g (50.00 mmol) NH4Cl in 35 ml ace-
tonitrile, 3.11 ml (20.00 mmol) 25% NH4OH was added and
then heated under reflux for 3 h.After cooling to room tempera-
ture, the insolubles were filtered off and concentrated to dry-
ness.The dark residue was subjected to flash chromatography
on silica gel (EtOAc) to afford 0.52 g (39%) of a red brown
syrup.
5d: yield 73%; mp 139–140°C; IR (KBr) νmax: 3200, 3030,
2970, 1400, 730 cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.31 (s,
1H, C2-H), 9.29 (s, 2H, C4-H, C6-H), 4.12 (d, 2H, J = 2.5 Hz,
SCH2), 2.28 (t, 1H, J = 2.5 Hz, CH);13C NMR (75 MHz, CDCl3)
δ: 159.0 (C2), 155.9 (C4, C6), 154.6 (C3Ј), 152.0 (C4Ј), 126.2
(C5), 78.1 (-CϵCH), 72.0 (-CϵCH), 21.7 (SCH2); Anal. calcd.
for C9H6N4S2: C, 46.14; H, 2.58; N, 23.91; S, 27.37. Found: C,
46.54; H, 2.52; N, 24.11; S, 27.44.
IR (KBr) νmax:3400 (NH), 2200 (CN), 1560, 1410 cm–1;1H NMR
(300 MHz, CDCl3) δ:9.27 (s, 1H, C2-H), 8.98 (s, 2H, C4-H, C6-
H), 5.03 (s, 1H, CHCN), 2.11 (br s, 2H, NH);13C NMR (50 MHz,
CDCl3) δ: 158.6 (C2), 155.3 (C4, C6), 130.0 (C5), 119.1 (CN),
43.1 (CCN); C6H6N4 (134.0591), MS: m/z = 134.0591.
Preparation of 5-(4-Chloro-[1,2,5]thiadiazol-3-yl)pyrimidine (4)
To a cooled (0°C) and stirred solution of 0.89 ml (11.18 mmol,
3.0 eq) S2Cl2 in 30 ml DMF, a solution of 0.50 g (3.73 mmol)
amino-pyrimidine-5-yl-acetonitrile in 10 ml DMF was added
dropwise maintaining the temperature below 5°C.The reaction
was slowly warmed to 80°C then stirring was continued for 2 h.
After cooling to room temperature, the reaction was neutralized
with NaOH solution and then extracted with EtOAc.The organic
layer was dried over MgSO4, then concentrated. The residue
was purified with flash chromatography on silica gel (20%
EtOAc-Hex) to give 0.54 g (73%) of the title compound as a
white solid. Recrystallization from EtOAc yielded white
needles.
5e: yield 79%; mp 45–47°C; IR (KBr) νmax: 2960, 1550,
1405 cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.34 (s, 2H, C4-H,
C6-H), 9.29 (s, 1H, C2-H), 3.26 (d, 2H, SCH2), 2.07 (m, 1H,
CH), 1.07 (d, 6H, 2 × CH3); 13C NMR (75 MHz, CDCl3) δ: 158.7
(C2), 157.1 (C3Ј), 155.9 (C4, C6), 152.0 (C4Ј), 126.6 (C5), 41.8
(SCH2), 28.2 (CH), 21.9 (CH3); C10H12N4S2 (252.0503), MS: m/
z = 252.0502.
5f: yield 73%; mp 43–44°C; IR (KBr) νmax: 2970, 2920, 2880,
1190, 730 cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.33 (s, 2H, C4-
H, C6-H), 9.30 (s, 1H, C2-H), 3.35 (t, 2H, SCH2), 1.81 (m, 2H,
CH2), 1.43 (m, 4H, 2 × CH2), 0.92 (t, 3H, CH3); 13C NMR
(75 MHz, CDCl3) δ: 158.7 (C2), 157.0 (C3Ј), 155.9 (C4, C6),
152.0 (C4Ј), 126.7 (C5), 33.2, 30.9, 28.6, 22.1 (Pentyl CH2),
13.8 (CH3); Anal. calcd. for C11H14N4S2: C, 49.60; H, 5.30; N,
21.03; S, 24.07. Found: C, 49.86; H, 5.58; N, 21.38; S, 24.03.
mp 135–136°C; IR (KBr) νmax: 3050, 1590, 1550, 1460, 1180
cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.39 (s, 2H, C4-H, C6-H),
9.35 (s, 1H, C2-H); 13C NMR (75 MHz, CDCl3) δ: 159.2 (C2),
155.9 (C4, C6), 152.3 (C3Ј), 143.5 (C4Ј), 125.2 (C5); Anal.
calcd.for C6H3ClN4S:C, 36.3;H, 1.5;N, 28.2;S, 16.1.Found:C,
36.1; H, 1.6; N, 27.9; S, 15.9.
5g: yield 53%; mp 79–80°C; IR (KBr) νmax: 3040, 2930, 1400,
980, 720 cm–1;1H NMR (300 MHz, CDCl3) δ:9.27 (s, 3H, C2-H,
C4-H, C6-H), 7.35 (m, 5H, aromatic H), 4.57 (s, 2H, SCH2);13
C
General procedure for the preparation of 5-(4-alkylsulfanyl-
[1,2,5]thiadiazol-3-yl)pyrimidines (5)
NMR (75 MHz, CDCl3) δ: 158.8 (C2), 156.2 (C3Ј), 155.9 (C4,
C6), 152.0 (C4Ј), 135.9 (C5), 129.1, 127.8, 127.8, 126.4 (aro-
matic C), 38.1 (SCH2);Anal.Calcd.for C13H10N4S2:C, 54.52;H,
3.52; N, 19.56; S, 22.39. Found: C, 54.81; H, 3.51; N, 19.96; S,
22.55.
5-(4-chloro-[1,2,5]thiadiazol-3-yl)pyrimidine (4) 0.50 g (2.52
mmol) was dissolved in 20 ml dimethylformamide. Sodium hy-
drosulfide hydrate (10.08 mmol) was added to this at room tem-
perature.After heating to 100°C stirring was continued for 24 h.
The reaction was then cooled to room temperature, then K2CO3
(7.56 mmol) and the appropriate alkyl halide (3.78 mmol) was
added, and the resulting mixture was stirred at the same tem-
perature for 5–24 h.The reaction mixture was dissolved in wa-
ter, and extrated with ethyl acetate.The organic layer was dried
over MgSO4 then the solvent was evaporated under reduced
pressure.The residue was subjected to flash chromatography
on silica gel (20% EtOAc-Hex) to give the title compounds.
5h: yield 72%; mp 107–108°C; IR (KBr) νmax: 3050, 3020,
2930, 1400, 970 cm–1; 1H NMR (300 MHz, CDCl3) δ: 9.27 (s,
3H, C2-H, C4-H, C6-H), 7.21 (ABq, 4H, aromatic H), 4.53 (s,
2H, SCH2), 2.33 (s, 3H, CH3); 13C NMR (75 MHz, CDCl3) δ:
158.8 (C2), 156.3 (C3Ј), 155.9 (C4, C6), 152.0 (C4Ј), 137.7
(C5), 132.7, 129.3, 129.0, 126.4 (aromatic C), 37.4 (SCH2),
21.1 (CH3); Anal. calcd. for C14H12N4S2: C, 55.97; H, 4.03; N,
18.65; S, 21.35. Found: C, 56.01; H, 4.12; N, 18.94; S, 21.43.

234 Jung et al.
Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
5i:yield 72%;mp 88–90°C;IR (KBr) νmax:3030, 1405 cm–1;1H
NMR (300 MHz, CDCl3) δ:9.28 (s, 1H, C2-H), 9.27 (s, 2H, C4-
(75 MHz, DMSO-d6) δ:164.4 (CO2H), 155.9 (C3Ј), 151.1 (C4Ј),
134.9 (C6), 96.4 (C5), 79.7 (C), 74.2 (CH), 61.1 (C2), 51.1 (C4),
39.1 (NCH3), 21.3 (SCH2); C10H12N4S2 (252.0503), MS: m/z =
252.0503.
H, C6-H), 7.30 (ABq, 4H, aromatic H), 4.52 (s, 2H, SCH2); 13
C
NMR (75 MHz, CDCl3) δ: 158.7 (C2), 155.8 (C4, C6), 155.6
(C3Ј), 151.9 (C4Ј), 134.5, 133.6, 130.4, 128.7 (aromatic C),
126.3 (C5), 36.7 (SCH2);Anal.calcd for C13H9ClN4S2:C, 48.67;
H, 2.83; N, 18.14; S, 19.99. Found: C, 49.03; H, 2.85; N, 17.41;
S, 20.05.
7e: overall yield 28%; mp 158–159°C; IR (KBr) νmax: 3280,
2960, 1630 cm–1; 1H NMR (300 MHz, DMSO-d6) δ: 8.07 (br s,
2H, CO2H), 7.63 (s, 1H, C6-H), 7.18 (br s, 1H, NH), 4.28 (s,
2H, C2-H), 3.99 (s, 2H, C4-H), 3.21 (d, 2H, SCH2), 2.70 (s, 3H,
NCH3), 1.98 (m, 1H, CH), 0.99 (d, 6H, 2 × CH3); 13C NMR (75
MHz, DMSO-d6) δ: 164.3 (CO2H), 155.9 (C3Ј), 153.0 (C4Ј),
134.7 (C6), 96.6 (C5), 61.1 (C2), 51.2 (C4), 41.2 (SCH2), 39.1
(NCH3), 27.9 (CH), 21.9 (CH3); C11H18N4S2 (270.0973), MS:
m/z = 270.0973.
General procedure for the preparation of 5-(4-alkylsulfanyl-
[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3,4-tetrahydropyrimidine
oxalate salts (7)
A solution of 3.55 mmol 5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-
yl)pyrimidine (5) and 42.65 mmol methyl iodide in 10 ml ace-
tone was heated under reflux for 48 h.Then the solvent and ex-
cess methyl iodide were removed on a rotary evaporator to give
crude 5-(4-alkylsulfanyl-[1,2,5]thiadiazol-3-yl)-3-methylpyri-
midium iodide (6).Without further purification, the salt was dis-
solved in 10 ml MeOH then cooled to low temperature
(0–30°C). To this portions of 3.91 mmol NaBH4 were added.
The reaction mixture was allowed to come to 0°C, then it was
concentrated in vacuo to dryness.The residue was dissolved in
CH2Cl2 then washed with water. The organic layer was dried
over MgSO4, and concentrated. The residue was subjected to
flash chromatography on silica gel (10% MeOH-EtOAc) to give
a red brown syrup. The resultant oily product, 5-(4-alkylsulfa-
nyl-[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3,4-tetrahydropyrimi-
dine, was dissolved in 2 ml MeOH and then to this a solution of
1.1 eq oxalic acid in 0.5 ml MeOH was added at room tempera-
ture.The resulting mixture was stirred for about 1 h.The precipi-
tates were collected by filtration and washed with small amouts
of cold MeOH and finally dried under vacuum to give the
oxalate salts 7 as a pale yellow powder.
7f:overall yield 9%;mp 142-144°C;IR (KBr) νmax:3240, 2930,
1630 cm–1;1H NMR (300 MHz, DMSO-d6) δ:7.57 (s, 1H, C6-H),
7.05 (br s, 1H, NH), 4.84 (br s, 2H, CO2H), 4.21 (s, 2H, C2-H),
3.92 (s, 2H, C4-H), 3.29 (t, 2H, SCH2), 2.65 (s, 3H, NCH3),
1.71 (m, 2H, CH2), 1.33 (m, 4H, 2 × CH2), 0.86 (t, 3H, CH3);13
C
NMR (75 MHz, DMSO-d6) δ: 164.1 (CO2H), 155.9 (C3Ј), 153.0
(C4Ј), 134.7 (C6), 96.6 (C5), 61.1 (C2), 51.2 (C4), 39.2 (NCH3),
32.7, 30.6, 28.3, 21.9 (pentyl CH2), 14.1 (CH3); C12H20N4S2
(284.1129), MS: m/z = 284.1129.
7g: overall yield 3%; mp 147–149°C; IR (KBr) νmax: 3290,
3030, 1630 cm–1;1H NMR (300 MHz, DMSO-d6) δ:7.52 (s, 1H,
C6-H), 7.33 (m, 5H, aromatic H), 7.05 (br s, 1H, NH), 5.65 (br s,
2H, CO2H), 4.57 (s, 2H, SCH2), 4.22 (s, 2H, C2-H), 3.93 (s,
2H, C4-H), 2.66 (s, 3H, NCH3); 13C NMR (75 MHz, DMSO-d6)
δ: 163.8 (CO2H), 155.9 (C3Ј), 152.4 (C4Ј), 134.9 (C6), 136.7,
129.4, 128.7, 127.7 (aromatic C), 96.6 (C5), 61.3 (C2), 51.3
(C4), 40.5 (SCH2), 39.9 (NCH3); C14H16N4S2 (304.0816), MS:
m/z = 304.0817.
7h: overall yield 9%; mp 151–153°C; IR (KBr) νmax: 3280,
3020, 1630 cm–1;1H NMR (300 MHz, DMSO-d6) δ:7.52 (s, 1H,
C6-H), 7.23, (ABq, 4H, aromatic H), 7.10 (br s, 3H, CO2H, NH),
4.52 (s, 2H, SCH2), 4.25 (s, 2H, C2-H), 3.97 (s, 2H, C4-H),
2.69 (s, 3H, NCH3), 2.25 (s, 3H, CH3); 13C NMR (75 MHz, DM-
SO-d6) δ: 164.2 (CO2H), 155.7 (C3Ј), 152.6 (C4Ј), 134.8 (C6),
137.0, 133.6, 129.3, 129.2 (aromatic C), 96.5 (C5), 61.1 (C2),
51.2 (C4), 39.0 (NCH3), 36.7 (SCH2), 20.9 (CH3); C15H18N4S2
(318.0973), MS: m/z = 318.0974.
7a: overall yield 19%; mp 145–146°C; IR (KBr) νmax: 3290,
3020, 2620, 1630 cm–1; 1H NMR (300 MHz, DMSO-d6) δ: 8.57
(br s, 2H, CO2H), 7.57 (s, 1H, C6-H), 7.28 (br s, 1H, NH), 4.31
(s, 2H, C2-H), 4.02 (s, 2H, C4-H), 2.73 (s, 3H, SCH3), 2.72 (s,
3H, NCH3); 13C NMR (75 MHz, DMSO-d6) δ: 164.6 (CO2H),
155.6 (C3Ј), 153.9 (C4Ј), 134.6 (C6), 96.6 (C5), 61.0 (C2), 51.1
(C4), 39.1 (NCH3), 15.8 (SCH3);C8H12N4S2 (228.0503), MS:m/
z = 228.0503.
7b: overall yield 26%; mp 147–149°C; IR (KBr) νmax: 3240,
2990, 2560, 1630 cm–1; 1H NMR (300 MHz, DMSO-d6) δ: 7.69
(br s, 2H, CO2H), 7.57 (s, 1H, C6-H), 7.23 (br s, 1H, NH), 4.29
(s, 2H, C2-H), 3.99 (s, 2H, C4-H), 3.29 (q, 2H, J = 7.0 Hz,
7i: overall yield 25%; mp 154–156°C; IR (KBr) νmax: 3280,
3040, 1630 cm–1; 1H NMR (300 MHz, DMSO-d6) δ: 8.30 (br s,
2H, CO2H), 7.52 (s, 1H, C6-H), 7.44 (ABq, 4H, aromatic H),
7.17 (br s, 1H, NH), 4.56 (s, 2H, SCH2), 4.26 (s, 2H, C2-H),
3.97 (s, 2H, C4-H), 2.69 (s, 3H, NCH3); 13C NMR (75 MHz,
DMSO-d6) δ: 164.3 (CO2H), 155.8 (C3Ј), 152.2 (C4Ј), 134.9
(C6), 136.1, 132.3, 131.2, 128.6 (aromatic C), 96.5 (C5), 61.6
(C2), 51.2 (C4), 36.0 (NCH3), 39.1 (SCH2); C14H15ClN4S2
(338.0427), MS: m/z = 338.0426.
SCH2), 2.71 (s, 3H, NCH3), 1.35 (t, 3H, J = 7.0 Hz, CH3); 13
C
NMR (75 MHz, DMSO-d6) δ: 164.3 (CO2H), 155.9 (C3Ј), 152.8
(C4Ј), 134.7 (C6), 96.6 (C5), 61.1 (C2), 51.2 (C4), 39.7 (NCH3),
27.2 (SCH2), 14.4 (CH3); C9H14N4S2 (242.0660), MS: m/z =
242.0657.
7c: overall yield 14%; mp 149–150; IR (KBr) νmax: 3280, 3000,
2930, 2610, 1630 cm–1;1H NMR (300 MHz, DMSO-d6) δ:10.09
(br s, 2H, CO2H), 7.57 (s, 1H, C6-H), 7.29 (br s, 1H, NH), 5.97
(m, 1H, CH=), 5.35, 5.16 (2 × d, 2H, =CH2), 4.32 (s, 2H, C2-H),
Biological methods
Receptor binding assay
4.02 (s, 2H, C4-H), 3.98 (d, 2H, SCH2), 2.74 (s, 3H, NCH3);13
C
The binding of compounds to the muscarinic M1 receptor (M1)
was performed by the radioligand binding assay as described
previously [16, 17]. Binding affinity was determined indirectly
by the ability of compounds to compete with 1 nM [3H]-N-meth-
ylscopolamine (NMS) in the suspension of cloned human M1
(h-1M) expressed in CHO cells (Biosignal Packard Inc., Mon-
treal, Canada).Nonspecific binding was evaluated by the inclu-
sion of 1 µM atropine in a separate set of samples.Each sample
contained approximately 16 µg of protein (h-M1) in 50 mM Tris
buffer (pH 7.2) and varying concentrations of each compound
in a final volume of 250 µl. Samples were incubated for 1 h at
NMR (75 MHz, DMSO-d6) δ: 164.5 (CO2H), 155.8 (C3Ј), 152.2
(C4Ј), 134.7 (C6), 133.0 (CH=), 119.2 (=CH2), 96.4 (C5), 60.9
(C2), 51.1 (C4), 39.1 (NCH3), 35.4 (SCH2); C10H14N4S
(242.0660), MS: m/z = 242.0656.
7d: overall yield 53%, mp 145–147°C; IR (KBr) νmax: 3280,
2925, 1635 cm–1; 1H NMR (300 MHz, DMSO-d6) δ: 7.75 (br s,
2H, CO2H), 7.47 (s, 1H, C6-H), 7.24 (br s, 1H, NH), 4.28 (s,
2H, C2-H), 4.16 (d, 2H, J = 2.3 Hz, SCH2), 3.99 (s, 2H, C4-H),
3.20 (t, 1H, J = 2.3 Hz, CH), 2.70 (s, 3H, NCH3); 13C NMR

Arch. Pharm. Pharm. Med. Chem. 2003, 336, 230–235
Methyl-1,2,3,4-Tetrahydropyrimidine Oxalate Salts 235
27°C in shaking incubator and then filtered through Wallac
glass fiber filtermat (GF/C) using Inotech cell harvester of 96-
well format. The radioactivity bound to filter was counted by
Micro-β counter (Wallac, Turku, Finland).
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NEW +++ NEW +++ NEW +++ NEW
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