Synthesis of 5-(4-alkoxy-[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/(SICI)1521-4184(20005)333:5<113::AID-ARDP113>3.0.CO;2-9

The synthesis and biological testing of 5-(4-alkoxy-[1,2,5]thiadiazol-3- yl)-3-methyl-1,2,3,4-tetrahydropyrimidine oxalate salts 8 as muscarinic receptor agonists are described. The key intermediate 4 was obtained by modified Strecker reaction and cyclization of starting material 1. Subsequent alkoxy substitution, quaternization, and reduction afforded 7. For the sake of purity and stability of the final products 8, the 3-methyl-1,2,3,4- tetrahydropyrimidines were obtained as oxalic acid salts. All final 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/(SICI)1521-4184(20005)333:5<113::AID-ARDP113>3.0.CO;2-9

Muscarinic Receptor Agonists
113
Synthesis of 5-(4-Alkoxy-[1,2,5]thiadiazol-3-yl)-3-methyl-
1,2,3,4-tetrahydropyrimidine Oxalate Salts and Their Evaluation
as Muscarinic Receptor Agonists
Jewn-Giew Park, Mi-Jeoung Lee, Jae Yang Kong, and Myung Hee Jung*
Korea Research Institute of Chemical Technology, P.O. Box 107, Yusong, Taejon 305-600, Korea
Key Words: Muscarinic receptor agonists; binding assay; milameline; 1,2,3,4-tetrahydropyrimidine
[8]
the literature . An aqueous solution of 1 was treated with
potassium cyanide, then the resulting cyanohydrin 2 was
isolated and purified in 67% yield (Scheme 1). The cyanohy-
Summary
The synthesis and biological testing of 5-(4-alkoxy-[1,2,5]thiadi-
azol-3-yl)-3-methyl-1,2,3,4-tetrahydropyrimidine oxalate salts 8
as muscarinic receptor agonists are described. The key intermedi-
ate 4 was obtained by modified Strecker reaction and cyclization
of starting material 1. Subsequent alkoxy substitution, quaterniza-
tion, and reduction afforded 7. For the sake of purity and stability
of the final products8, the3-methyl-1,2,3,4-tetrahydropyrimidines
were obtained as oxalic acid salts. All final compounds were
examined in vitro for their binding affinities to the cloned human
muscarinic receptor by the [3H]-NMS binding assay.
drin 2 was treated with NH Cl/NH OH to furnish the amino-
4
4
[9]
nitrile 3. Under one-pot Strecker conditions this reaction
gave only a very low yield of 3. The key intermediate,
5-(4-chloro-[1,2,5]thiadiazol-3-yl)pyrimidine 4 was obtain-
ed by treating 3 with sulfur monochloride in DMF in 73%
yield. Nucleophilic substitution of the chlorine in 4 with
1
various sodium alkoxides afforded the compounds 5 ( H
13
NMR data and C NMR data are summarized in Table 1). A
large excess of methyl iodide in boiling acetone gave the
3-quaternized pyrimidine salts 6. The crude pyrimidine salts
were reduced with sodium borohydride at –30 °C in methanol
to give 5-(4-alkoxy-[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3,4-
tetrahydropyrimidines 7 as the sole product. For enhanced
purity and stability, compounds 7 were further treated with
oxalic acid to afford the oxalate salts 8. The structure of 7 can
Introduction
The quest for more effective treatments of neurodegenera-
tive diseases, especially Alzheimer’s disease (AD), is becom-
ing more urgent. Recent research has revealedthatmuscarinic
compounds actually slow the progress of AD and are bene- be deduced from X-ray crystallographic data of pyrimidinyl-
[1]
ficial in the treatment of AD symptoms . Arecoline
benzoxazole which were previously obtained via an identical
chemical pathway . Also, in the H NMR spectra of 8 in
[2]
[10]
1
(Chart 1) , a naturally occurring alkaloid and unselective
muscarinic agonist, had been used for the AD patients in early
clinical trials. Continued efforts to improve the pharma-
cological and pharmacokinetic properties towards a clinically
meaningful profile have led to the emergence of milameline
(Chart 1) . On the other hand, xanomeline (Chart 1) , in
which a 4-hexyloxy-[1,2,5]thiadiazole ring replaces the
methyl ester of arecoline and the methoxyimino group of
DMSO-d , all the C6-H protons were observed as singlets at
7.68–7.75 ppm. The two protons in C4-position were also
found as singlets as well, at 3.98–4.01 ppm (Table 2).
6
Table 1. 1H NMR (CDCl3) and 13C NMR data (CDCl3) of the compound 5.
[3]
[4]
——————————————————————————————
Proton
Carbon
Compd
δ [ppm]
δ [ppm]
2-H
4,6-H C-2
C-5
C-4,6 C-3′
C-4′
——————————————————————————————
Chart 1. Muscarinic agonists.
5a
5b
5c
5d
5e
5f
9.25
9.25
9.26
9.27
9.26
9.26
9.26
9.23
9.22
9.24
9.46
9.49
9.49
9.49
9.49
9.49
9.49
9.47
9.46
9.45
158.3 125.4 154.9 163.3 141.8
158.4 125.7 155.1 162.8 141.9
158.5 125.6 155.2 162.4 140.0
158.6 125.3 155.2 161.5 142.1
158.4 125.7 155.1 163.1 142.0
158.3 125.6 154.9 162.9 141.9
158.5 125.9 155.3 163.1 142.1
158.4 125.6 155.1 162.6 142.1
158.4 125.6 155.2 162.6 142.1
158.5 125.5 155.1 162.3 142.1
milameline, has been reported as a potent functional M
selective muscarinic agonist . The present paper describes
an attempt to synthesize 3-methyl-1,2,3,4-tetrahydro-
1
[5]
pyrimidine bioisosteric congeners as muscarinic receptor
[6,7]
agonists of tetrahydropyridine derivatives
xanomeline, and their biological evaluation.
, especially
5g
5h
5i
Synthesis
5j
The starting material, 5-pyrimidinecarboxaldehyde 1, was
obtained from 4,6-dihydroxypyrimidine in accordance with
——————————————————————————————
Arch. Pharm. Pharm. Med. Chem.
© WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000 0365-6233/00/0505/0113 $17.50 +.50/0

114
Park, Lee, Kong, and Jung
Table 2. 1H NMR data (DMSO) and 13C NMR data (DMSO) of the compound 8.
—————————————————————————————————————————————————————————
Proton
δ [ppm]
6-H
Carbon
δ [ppm]
C-5
Compd
2-H
4-H
N-CH3
C-2
C-4
C-6
C-3′
C-4′
—————————————————————————————————————————————————————————
8a
8b
8c
8d
8e
8f
4.29
4.32
4.32
4.31
4.32
4.31
4.33
4.28
4.29
4.30
3.98
4.01
4.01
3.99
4.01
3.99
4.02
3.99
3.99
4.01
7.70
7.75
7.74
7.69
7.74
7.72
7.77
7.70
7.68
7.69
2.73
2.75
2.74
2.73
2.74
2.74
2.76
2.72
2.72
2.74
60.9
60.9
60.9
60.9
60.9
60.9
61.1
60.9
60.9
60.9
50.6
50.6
50.6
50.5
50.6
50.6
50.7
50.6
50.6
50.6
96.3
96.4
96.3
96.2
96.5
96.5
96.6
96.4
96.5
96.3
134.3
134.1
134.2
134.3
134.1
134.1
134.1
134.2
134.1
134.2
160.8
160.1
159.8
158.9
160.3
160.2
160.2
159.9
159.9
159.7
146.7
146.6
146.7
146.7
146.7
146.7
141.8
141.8
146.7
146.7
8g
8h
8i
8j
—————————————————————————————————————————————————————————
Scheme 1. Reagents: i) KCN/HOAc; ii) NH4Cl/NH4OH; iii) S2Cl2;
iv) Na/ROH; v) CH3I; vi) NaBH4; vii) (CO2H)2.
Arch. Pharm. Pharm. Med. Chem. 333, 113–117 (2000)

Muscarinic Receptor Agonists
115
Hydroxypyrimidin-5-ylacetonitrile (2)
Results and Discussion
KCN (8.14 g, 125.00 mmol) in water (50 ml) was cooled to 5 °C, and then
were added portions of 5-pyrimidinecarboxaldehyde (5.40 g, 50.00 mmol)
maintaining the temperature below 10 °C. When all of the aldehyde had been
added, acetic acid (7.16 ml, 125.00 mmol) was added dropwise at a tempera-
ture below 10 °C. After stirring for 2 h at room temperature the mixture was
cooled back to 5 °C and the precipitates were collected by filtration. The filter
cake was washed with cold water and then dried under vacuum. The product
was further purified by flash chromatography on silica gel (ethyl acetate) to
give 4.55 g (67%) of the title compound as a white powder. Mp 142–144 °C.–
IR (KBr) ν: 3200 (OH), 3020 (Ar-H), 2800 (CH), 1560 (C=C) cm–1.– 1H
NMR (300 MHz, [D6]acetone) δ: 9.23 (s, 1H, 2-H), 8.99 (s, 2H, 4-H, 6-H),
6.59 (br. s, 1H, OH), 6.06 (s, 1H, CHCN).– 13C NMR (75 MHz, [D6]acetone)
δ: 159.6 (C-2), 155.9 (C-4, C-6), 131.7 (C-5), 119.1(CN), 59.7(CCN).- Anal.
C6H5N3O (135.0433).– MS: m/z = 135.0432.
Binding affinities of prepared compounds for M receptor
were sought by their ability to displace [ H]-NMS from
1
3
cloned human M receptor (h-M ) expressed in CHO cells.
1
1
3
Table 3 shows the percentages of inhibition of [ H]-NMS
binding to h-M at the 100 µM and IC values of the
1
50
compounds. The affinities of other M agonists are also
1
presented for comparison. Most 3-methyl-1,2,3,4-tetrahy-
dropyrimidines, 8c, 8d, 8f, 8g, 8h, 8i, and 8j, synthesized as
bioisosteric congeners of tetrahydropyridine derivatives,
showed higher binding affinities for h-M than those of
1
arecoline and milameline, but much lower affinities than that
of xanomeline. There was a ranking order in binding affinity
for h-M among compounds prepared and tested, depending
1
on the length of alkyl substituent, i.e. compound with longer
chain showed higher affinity (8g > 8f > 8c > 8b > 8a).
Compounds with benzyl substituent, 8h, 8i, and 8j, showed
Aminopyrimidin-5-ylacetonitrile (3)
To a stirred solution of hydroxypyrimidin-5-ylacetonitrile (1.35 g,
10.00 mmol) and NH4Cl (2.67 g, 50.00 mmol) in acetonitrile (35 ml) was
added 25% NH4OH (3.11 ml, 20.00 mmol) and the mixture was heated under
reflux for 3 h. After cooling to room temperature the insolubles were filtered
off, and the filtrate was concentrated to dryness. The dark residue was
subjected to flash chromatography on silica gel (ethyl acetate) to afford
0.52 g (39%) of a red brown syrup. IR (KBr) ν: 3400 (NH), 2230 (CN), 1560
(C=C) cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.27 (s, 1H, 2-H), 8.98 (s, 2H,
4-H, 6-H), 5.03 (s, 1H, CHCN), 2.11 (br. s, 2H, NH2).– 13C NMR (50 MHz,
CDCl3) δ: 158.6 (C-2), 155.3 (C-4, C-6), 130.0 (C-5), 119.1 (CN), 43.1
(CCN).– C6H6N4 (134.0591), MS: m/z = 134.0591.
similar affinity to h-M .
1
Table 3. Inhibition of [3H]-NMS binding to h-M1 by 3-methyl-1,2,3,4-tetra-
hydropyrimidines.
——————————————————————————————
Compounds
% Inhibition
IC50
100 µM
Mean ± S.E
——————————————————————————————
8a
40.6 ± 5.0
57.7 ± 5.8
89.1 ± 2.4
88.0 ± 0.4
60.6 ± 14.1
82.5 ± 6.0
99.7 ± 0.0
81.1 ± 7.8
71.7 ± 11.9
78.7 ± 10.4
101.4 ± 0.9
65.3 ± 3.3
34.1 ± 5.3
144.0 ± 23.1
86.8 ± 22.4
23.0 ± 7.0
16.2 ± 2.8
83.4 ± 34.2
24.5 ± 5.3
3.4 ± 1.0
8b
5-(4-Chloro-[1,2,5]thiadiazol-3-yl)pyrimidine (4)
8c
To a cooled (3 °C) and stirred solution of S2Cl2 (0.89 ml, 11.18 mmol,
3.0 eq) in DMF (30 ml) was added dropwise a solution of aminopyrimidine-
5-ylacetonitrile (0.50 g, 3.73 mmol) in DMF (10 ml) maintaining the tem-
perature below 5 °C. The reaction was slowly warmed to 80 °C and stirring
was continued for 2 h. After cooling to room temperature, the mixture was
neutralized with NaOH solution, then extracted with ethyl acetate. The
organic layer was dried over MgSO4, then concentrated. The residue was
purified with flash chromatography on silica gel (20% ethyl acetate-hexane)
to give 0.54 g (73%) of the title compound as a white solid. Recrystallized
from ethyl acetate gave white needles. Mp 135–136 °C.– IR (KBr) ν: 3050
(Ar-H), 1590 (C=C), 710 (C-Cl) cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.39
(s, 2H, 4-H, 6-H), 9.35 (s, 1H, 2-H).– 13C NMR (75 MHz, CDCl3) δ: 159.2
(C-2), 155.9 (C-4, C-6), 152.3 (C-3′), 143.5 (C-4′), 125.2 (C-5).– Anal. Calc.
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.
8d
8e
8f
8g
8h
19.7 ± 8.3
51.3 ± 21.0
42.1 ± 20.3
0.3 ± 0.0
8i
8j
xanomeline
milameline
arecoline
60.9 ± 8.8
233.1 ± 44.8
——————————————————————————————
* Data represent the mean ± S.E.M from three assays each performed in
duplicate.
General Procedure for the Preparation of 5-(4-Alkoxy-[1,2,5]thiadiazol-
3-yl)pyrimidine (5)
Acknowledgment
5-(4-Chloro-[1,2,5]thiadiazol-3-yl)pyrimidine (2.52 mmol) was added at
room temperature to Na metal (5.3 eq) dissolved in an appropriate alcohol
(20 ml). The mixture was heated to 50 °C and then stirring was continued for
1 h. In the cases of higher boiling alcohols such as 4-methylbenzyl alcohol,
the NaH/THF system was used. Insolubles were filtered off, and the filtrate
was concentrated to dryness. The residue was dissolved in water, extracted
with dichloromethane, and the organic layer, dried over magnesium sulfate,
was evaporated under reduced pressure. The residue was purified by flash
chromatography on silica gel (20% ethyl acetate-hexane) to give the title
compounds.
5a: yield 96%.– Mp 112–113 °C.– IR (KBr) ν: 3050 (Ar-H), 1520 (C=C)
cm–1.– 1H NMR (200 MHz, CDCl3) δ: 9.46 (s, 2H, 4-H, 6-H), 9.25 (s, 1H,
2-H), 4.25 (s, 3H, OCH3).– 13C NMR (50 MHz, CDCl3) δ: 163.3 (C-3′),
158.3(C-2), 154.9 (C-4, C-6), 141.8 (C-4′), 125.4(C-5), 57.9(OCH3).– Anal.
Calcd. for C7H6N4OS: C, 43.3; H, 3.1; N, 28.9; S, 16.5. Found: C, 43.3; H,
3.3; N, 28.8; S, 16.5.
We wish to thank the Korea Ministry of Science and Technology (KN
9925-01) for financial grants.
Experimental
Melting points were determined on a Thomas-Hoover apparatus and are
uncorrected. Infrared spectra were recorded on a Shimadzu 435 spectrometer
and Mattson Genesis II FTIR. Nuclear magnetic resonance spectra were
measured on a Brucker AM-300 spectrometer and a Varian Gemini-200.
Mass spectra were determined on JEOL JMA-DA 5000 mass data system
focusing high resolution mass spectrometers. In the 1H NMR data, ddt and
ABq denote doublet-doublet-triplet and AB quartet, respectively.
Arch. Pharm. Pharm. Med. Chem. 333, 113–117 (2000)

116
Park, Lee, Kong, and Jung
on a rotary evaporator to give crude 5-(4-alkoxy-[1,2,5]thiadiazol-3-yl)-
pyrimidinium methiodide 6. The methiodide 6 was dissolved in methanol
(10 ml) then cooled to –30 °C, and portions of sodium borohydride
(3.91 mmol) were added. The reaction temperature was allowed to reach
0 °C then the solution concentrated in vacuo to dryness. The residue was
dissolved in dichloromethanethen washed with water. The organic layer was
dried over magnesium sulfate, and concentrated. The residue was purified
by flash chromatography on silica gel (10% methanol-ethyl acetate) to give
a red brown syrup. The resultant product 7, was dissolved in methanol (2 ml,
some insolubles were filtered off through a short column of Celite) then a
solution of oxalic acid (1.1 eq) in methanol (0.5 ml) was added at room
temperature. The resulting mixture was stirred for 1 h. The precipitates were
collected by filtration and washed with a small amount of cold methanol,
then dried under vacuum to give the title compounds 8 as a pale yellow
powder.
5b: yield 93%.– Mp 110–112 °C.– IR (KBr) ν: 2985 (CH), 1510 (C=C)
cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.49 (s, 2H, 4-H, 6-H), 9.25 (s, 1H,
2-H), 4.61 (q, 2H, OCH2), 1.55 (t, 3H, CH3).– 13C NMR (75 MHz, CDCl3)
δ: 162.8 (C-3′), 158.4 (C-2), 155.1 (C-4, C-6), 141.9 (C-4′), 125.7 (C-5), 67.3
(OCH2), 14.5 (CH3).– Anal. Calcd. for C8H8N4OS: C, 46.1; H, 3.9; N, 26.9;
S, 15.4. Found: C, 45.9; H, 3.9; N, 26.8; S, 15.5.
5c: yield 93%.– Mp 50–51 °C.– IR (KBr) ν: 3075 (Ar-H), 2950 (CH), 1510
(C=C) cm–1.– 1H NMR (200 MHz, CDCl3) δ: 9.49 (s, 2H, 4-H, 6-H), 9.26
(s, 1H, 2-H), 6.15 (ddt, 1H, J = 17.0, 10.6, 5.6 Hz, CH=CH2), 5.49 (d, 1H, J
= 17.0 Hz, C=CHtrans), 5.39 (d, 1H, J = 10.6 Hz, C=CHcis), 5.06 (d, 2H, J
= 5.6 Hz, OCH2).– 13C NMR (75 MHz, CDCl3) δ: 162.4 (C-4′), 158.5 (C-2),
155.2 (C-4, C-6), 142.0 (C-3′), 131.4 (CH=CH2), 125.6 (C-5), 119.7
(CH=CH2), 71.9 (OCH2).– Anal. Calcd. for C9H8N4OS: C, 49.1; H, 3.7; N,
25.4; S, 14.6. Found: C, 48.8; H, 3.8; N, 25.7; S, 14.6.
5d: yield 48%.– Mp 118–119 °C.– IR (KBr) ν: 3250 (≡CH), 3030 (Ar-H),
2930 (CH), 2120 (C≡C)cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.49 (s, 2H,
4-H, 6-H), 9.27 (s, 1H, 2-H), 5.18 (d, 2H, J = 2.0 Hz, OCH2), 2.64 (t, 1H, J
= 2.0 Hz, CH).– 13C NMR (75 MHz, CDCl3) δ: 161.5 (C-3′), 158.6 (C-2),
155.2 (C-4, C-6), 142.1 (C-4′), 125.3 (C-5), 76.9 (C≡), 76.4 (≡CH), 58.5
(OCH2).– C9H6N4OS (218.0262), MS: m/z = 218.0265.
8a: overall yield 15%.– Mp 150–152 °C.– IR (KBr) ν: 3290–3200 (OH),
1
2950 (CH), 1635 (C=C) cm–1.– H NMR (300 MHz, [D6]DMSO) δ: 9.61
(br. s, 2 H, 2 × CO2H), 7.70 (s, 1 H, 6-H), 7.22 (br. s, 1 H, NH), 4.29 (s, 2 H,
2-H), 4.08 (s, 3 H, OCH3), 3.98 (s, 2 H, 4-H), 2.73 (s, 3 H, NCH3).– 13C NMR
(75 MHz, [D6]DMSO) δ: 164.6 (CO2H), 160.8 (C-3′), 146.7 (C-4′), 134.3
(C-6), 96.3 (C-5), 60.9 (C-2), 58.1 (OCH3), 50.6 (C-4), 39.1 (NCH3).–
C8H12N4OS (212.0732).– MS: m/z = 212.0729.
5e: yield 92%.– Mp 45–47 °C.– IR (KBr) ν: 2960 (CH), 1510 (C=C)
cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.49 (s, 2H, 4-H, 6-H), 9.26 (s, 1H,
2-H), 4.33 (d, 2H, OCH2), 2.23 (m, 1H, CH), 1.09 (d, 6H, 2 × CH3).– 13
C
8b: overall yield 14%.– Mp 155–157 °C.– IR (KBr) ν: 3300–3200 (OH),
1
2980 (CH), 1630 (C=C) cm–1.– H NMR (300 MHz, [D6]DMSO) δ: 8.19
NMR (75 MHz, CDCl3) δ: 163.1 (C-3′), 158.4 (C-2), 155.1 (C-4, C-6), 142.0
(C-4′), 125.7 (C-5), 77.7 (OCH2), 27.9 (CH), 19.1 (CH3).– C10H12N4OS
(236.0732), MS: m/z = 236.0733.
5f: yield 89%.– Mp 59–61 °C.– IR (KBr) ν: 2950 (CH), 1510 (C=C)
cm–1.– 1H NMR (200 MHz, CDCl3) δ: 9.49 (s, 2H, 4-H, 6-H), 9.26 (s, 1H,
2-H), 4.55 (t, 2H, OCH2), 1.90 (m, 2H, CH2), 1.45 (m, 4H, 2 × CH2), 0.95
(t, 3H, CH3).–13C NMR (50MHz, CDCl3) δ: 162.9 (C-3′), 158.3 (C-2), 154.9
(C-4, C-6), 141.9 (C-4′), 125.6 (C-5), 71.5 (OCH2), 28.4, 27.9, 22.1 (pentyl
C), 13.8 (CH3).– Anal. Calcd. for C11H14N4OS: C, 52.8; H, 5.6; N, 22.4; S,
12.8. Found: C, 52.5; H, 6.1; N, 22.6; S, 12.9.
5g: yield 73%.– Mp 63–64 °C.– IR (KBr) ν: 2950 (CH), 1510 (C=C)
cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.49 (s, 2H, 4-H, 6-H), 9.26 (s, 1H,
2-H), 4.55 (t, 2H, OCH2), 1.90 (m, 2H, CH2), 1.50, 1.37 (m, 4H, 3 × CH2),
0.91 (t, 3H, CH3).– 13C NMR (75 MHz, CDCl3) δ: 163.1 (C-3′), 158.5 (C-2),
155.3 (C-4, C-6), 142.1 (C-4′), 125.9 (C-5), 71.8 (OCH2), 31.4, 28.8, 25.7,
22.5 (hexyl C), 14.0 (CH3).– Anal. Calcd. for C12H16N4OS: C, 54.5; H, 6.1;
N, 21.2; S, 12.1. Found: C, 54.7; H, 6.4; N, 20.9; S, 12.0.
5h: yield 90%.– Mp 107–108 °C.– IR (KBr) ν: 3060 (Ar-H), 2950 (CH),
1510 (C=C) cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.47 (s, 2H, 4-H, 6-H),
9.23 (s, 1H, 2-H), 7.39 (m, 5H, aromatic H), 5.57 (s, 2H, OCH2).– 13C NMR
(75MHz, CDCl3)δ: 162.6 (C-3′), 158.4 (C-2), 155.1(C-4, C-6), 142.1(C-4′),
134.9, 128.8, 128.7, 128.3, (aromatic C), 125.6 (C-5), 73.1 (OCH2).– Anal.
Calcd. for C13H10N4OS: C, 57.8; H, 3.7; N, 20.7; S, 11.9. Found: C, 56.9;
H, 3.9; N, 20.9; S, 11.9.
(br. s, 2H, 2 × CO2H), 7.75 (s, 1H, 6-H), 7.21 (br. s, 1H, NH), 4.46 (q, 2H,
OCH2), 4.32 (s, 2H, 2-H), 4.01 (s, 2H, 4-H), 2.75 (s, 3H, NCH3), 1.39 (t, 3H,
CH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.4 (CO2H), 160.1 (C-3′),
146.6 (C-4′), 134.1 (C-6), 96.4 (C-5), 66.9 (OCH2), 60.9 (C-2), 50.6 (C-4),
39.0 (NCH3), 14.6 (CH3).– C9H14N4OS (226.0888).– MS: m/z = 226.0888.
8c: overall yield 21%.– Mp 153–155 °C.– IR (KBr) ν: 3300–3200 (OH),
3000 (Ar-H), 1630 (C=C) cm–1; 1H NMR (300 MHz, [D6]DMSO) δ: 7.74
(s, 1H, 6-H), 7.26 (br. s, 1H, NH), 6.66 (br. s, 2H, 2 × CO2H), 6.10 (m, 1H,
CH=), 5.37 (m, 2H, =CH2), 4.95 (d, 2H, OCH2), 4.32 (s, 2H, 2-H), 4.01 (s,
2H, 4-H), 2.74 (s, 3H, NCH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.7
(CO2H), 159.8 (C-3′), 146.7 (C-4′), 134.2 (C-6), 132.7 (CH=), 118.9 (=CH2),
96.3(C-5), 71.4(OCH2), 60.9(C-2), 50.6 (C-4), 39.0 (NCH3).– C10H14N4OS
(238.0888).– MS: m/z = 238.0888.
8d: overall yield 55%.– Mp 158–160 °C.– IR (KBr) ν: 3300–3200 (OH,
≡CH), 1630 (C=C) cm–1.– 1H NMR (300 MHz, [D6]DMSO) δ: 8.63 (br. s,
2H, 2 × CO2H), 7.69 (s, 1H, 6-H), 7.29 (br. s, 1H, NH), 5.13 (d, 2H, J = 2.0
Hz, OCH2), 4.31 (s, 2H, 2-H), 3.99 (s, 2H, 4-H), 3.67 (t, 1H, J = 2.0 Hz,
≡CH), 2.73 (s, 3H, NCH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.6
(CO2H), 158.9 (C-3′), 146.7 (C-4′), 134.3 (C-6), 96.2 (C-5), 78.9 (C≡), 78.6
(≡CH), 60.9 (C-2), 58.4 (OCH2), 50.5 (C-4), 39.1 (NCH3).– C10H12N4OS
(236.0732).– MS: m/z = 236.0729.
8e: overall yield 17%.– Mp 159–160 °C.– IR (KBr) ν: 3300–3000 (OH),
1
2965 (CH), 1630 (C=C) cm–1.– H NMR (300 MHz, [D6]DMSO) δ: 8.63
5i: yield 69%.– Mp 107–108 °C.– IR (KBr) ν: 3055 (Ar-H), 2950 (CH),
1510 (C=C) cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.46 (s, 2H, 4-H, 6-H),
9.22 (s, 1H, 2-H), 7.29 (ABq, 4H, aromatic H), 5.52 (s, 2H, OCH2), 2.37 (s,
3H, CH3).– 13C NMR (75 MHz, CDCl3) δ: 162.6 (C-3′), 158.4 (C-2), 155.2
(C-4, C-6), 142.1 (C-4′), 138.7, 131.9, 129.4, 128.5, (aromatic C), 125.6
(C-5), 73.1 (OCH2), 21.2 (CH3).– Anal. Calcd. for C14H12N4OS: C, 59.1; H,
4.3; N, 19.7; S, 11.3. Found: C, 58.6; H, 4.6; N, 19.6; S, 11.0.
5j: yield 79%.– Mp 96–97 °C.– IR (KBr) ν: 3050 (Ar-H), 2960 (CH), 1510
(C=C) cm–1.– 1H NMR (300 MHz, CDCl3) δ: 9.45 (s, 2H, 4-H, 6-H), 9.24
(s, 1H, 2-H), 7.41 (ABq, 4H, aromatic H), 5.34 (s, 2H, OCH2).– 13C NMR
(75MHz, CDCl3)δ: 162.3 (C-3′), 158.5 (C-2), 155.1(C-4, C-6), 142.1(C-4′),
134.7, 133.4, 129.8, 128.9, (aromatic C), 125.5 (C-5), 72.2 (OCH2).– Anal.
Calcd. for C13H9N4OClS: C, 51.2; H, 3.0; N, 18.4; S, 10.5. Found: C, 50.7;
H, 2.9; N, 18.4; S, 10.5.
(br. s, 2H, 2 × CO2H), 7.74 (s, 1H, 6-H), 7.29 (br. s, 1H, NH), 4.32 (s, 2H,
2-H), 4.20 (d, 2H, OCH2), 4.01 (s, 2H, 4-H), 2.74 (s, 3H, NCH3), 2.10 (m,
1H, CH), 0.98 (d, 6H, 2 × CH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.6
(CO2H), 160.3 (C-3′), 146.7 (C-4′), 134.1 (C-6), 96.5 (C-5), 76.9 (OCH2),
60.9 (C-2), 50.6 (C-4), 39.0 (NCH3), 27.7 (CH), 19.2 (CH3).– C11H18N4OS
(254.1201).– MS: m/z = 254.1204.
8f: overall yield 9%.– Mp 153–155 °C.– IR (KBr) ν: 3500–3200 (OH),
2950 (CH), 1630 (C=C) cm–1.– 1H NMR (300 MHz, [D6]DMSO) δ: 7.72 (s,
1H, 6-H), 7.24 (br. s, 1H, NH), 6.24 (br. s, 2H, 2 × CO2H), 4.40 (t, 2H, OCH2),
4.31 (s, 2H, 2-H), 3.99 (s, 2H, 4-H), 2.74 (s, 3H, NCH3), 1.77 (m, 2H, CH2),
1.35 (m, 4H, 2 × CH2), 0.88 (t, 3H, CH3).– 13C NMR (75 MHz, [D6]DMSO)
δ: 164.6 (CO2H), 160.2 (C-3′), 146.7 (C-4′), 134.1 (C-6), 96.5 (C-5), 71.0
(OCH2), 60.9 (C-2), 50.6 (C-4), 39.1 (NCH3), 28.2, 27.9, 22.1, 14.1 (pentyl
C).– C12H20N4OS (268.1358).– MS: m/z = 268.1357.
8g: overall yield 25%.– Mp 140–142 °C.– IR (KBr) ν: 3400–3250 (OH),
2950 (CH), 1630 (C=C) cm–1.– 1H NMR (300 MHz, [D6]DMSO) δ: 7.77 (s,
1H, 6-H), 7.21 (br. s, 1H, NH), 6.95 (br. s, 2H, 2 × CO2H), 4.46 (t, 2H, OCH2),
4.33 (s, 2H, 2-H), 4.02 (s, 2H, 4-H), 2.76 (s, 3H, NCH3), 1.45 (m, 2H, CH2),
1.34 (m, 6H, 3 × CH2), 0.91 (t, 3H, CH3).– 13C NMR (75 MHz, [D6]DMSO)
δ: 164.2 (CO2H), 160.2 (C-3′), 146.8 (C-4′), 134.1 (C-6), 96.6 (C-5), 70.9
General Procedure for the Preparation of 5-(4-Alkoxy-[1,2,5]thiadiazol-3-
yl)-3-methyl-1,2,3,4-tetrahydropyrimidines (7) and Their Oxalate Salts (8)
A solution of 5-(4-alkoxy-[1,2,5]thiadiazol-3-yl)pyrimidine 5
(3.55 mmol) and methyl iodide (42.65 mmol) in acetone (10 ml) was heated
under reflux for 48 h. The solvent and excess methyl iodide were removed
Arch. Pharm. Pharm. Med. Chem. 333, 113–117 (2000)

Muscarinic Receptor Agonists
117
(OCH2), 61.1 (C-2), 50.7 (C-4), 39.1 (NCH3), 31.1, 28.5, 25.4, 22.2 (hexyl
C), 14.1 (CH3).– C13H22N4OS (282.1514).– MS: m/z = 282.1515.
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 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).
8h: overall yield 26%.– Mp 153–155 °C.– IR (KBr) ν: 3300–3200 (OH),
3030 (Ar-H), 2940 (CH), 1630 (C=C) cm–1.– 1H NMR (300 MHz,
[D6]DMSO) δ: 8.79 (br. s, 2H, 2 × CO2H), 7.70 (s, 1H, 6-H), 7.74 (m, 5H,
aromatic H), 7.22 (br. s, 1H, NH), 5.49 (s, 2H, OCH2), 4.28 (s, 2H, 2-H), 3.99
(s, 2H, 4-H), 2.72 (s, 3H, NCH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.6
(CO2H), 159.9 (C-3′), 146.8 (C-4′), 134.2 (C-6), 136.0, 128.8, 128.7, 128.5
(aromatic C), 96.4(C-5), 72.4 (OCH2), 60.9 (C-2), 50.6 (C-4), 39.1 (NCH3).–
References
C
14H16N4OS (288.1045).– MS: m/z = 288.1045.
8i: overall yield 14%.– Mp 158–160 °C.– IR (KBr) ν: 3400–3200 (OH),
[1] R. M. Nitsch, J. H. Growdon, Biochem. Pharmacol. 1994, 47, 1275.
3030 (Ar-H), 2940 (CH), 1630 (C=C) cm–1.– 1H NMR (300 MHz,
[D6]DMSO) δ: 9.11 (br. s, 2H, 2 × CO2H), 7.68 (s, 1H, 6-H), 7.29, (ABq,
4H, aromatic H), 7.10 (br. s, 1H, NH), 5.43 (s, 2H, OCH2), 4.29 (s, 2H, 2-H),
3.99 (s, 2H, 4-H), 2.72 (s, 3H, NCH3), 2.29 (s, 3H, CH3).– 13C NMR
(75 MHz, [D6]DMSO) δ: 164.5 (CO2H), 159.9 (C-3′), 146.7 (C-4′), 134.1
(C-6), 138.1, 133.0, 129.4, 128.7 (aromatic C), 96.5 (C-5), 72.4 (OCH2), 60.9
(C-2), 50.6 (C-4), 39.1 (NCH3), 21.1 (CH3).– C15H18N4OS (302.1201).–
MS: m/z = 302.1203.
[2] E. K. Moltzen, R. E. Pederson, K. P. Bogeso, E. Meier, K. Frederiksen,
C. Sanchez, H. L. Lembol, J. Med. Chem. 1994, 37, 4085.
[3] a) J. E. Christie, A. Shering, J. Ferguson, A. I. Glen, Br. J. Psychiatry
1981, 138, 46. b) J. M. Palacios, R. Spiegel Prog. Brain Res. 1986, 70,
485.
[4] E. Toja, C. Bonetti, A. Butti, Eur. J. Med. Chem. 1992, 27, 519.
[5] P. Sauerberg, P. H. Olesen, J. Med. Chem. 1992, 35, 2274.
8j: overall yield 25%.– Mp 151–153 °C.– IR (KBr) ν: 3300–3200 (OH),
3040 (Ar-H), 1630 (C=C) cm–1.– 1H NMR (300 MHz, [D6]DMSO) δ: 8.44
(br. s, 2H, 2 × CO2H), 7.69 (s, 1H, 6-H), 7.49 (ABq, 4H, aromatic H), 7.23
(br. s, 1H, NH), 5.48 (s, 2H, OCH2), 4.30 (s, 2H, 2-H), 4.01 (s, 2H, 4-H),
2.74 (s, 3H, NCH3).– 13C NMR (75 MHz, [D6]DMSO) δ: 164.5 (CO2H),
159.7 (C-3′), 146.7 (C-4′), 134.2 (C-6), 135.1, 133.3, 130.4, 128.8 (aromatic
C), 96.3 (C-5), 71.6 (OCH2), 60.9 (C-2), 50.6 (C-4), 39.0 (NCH3).–
[6] C. E. Augelli-Szafran, C. J. Blankley, J. C. Jaen, D. W. Moreland, C.
B. Nelson, J. R. Penvose-Yi, R. D. Schwarz, A. J. Thomas, J. Med.
Chem. 1999, 42, 356.
[7] H. A. M. Mucke, J., Castañer, Drugs Future 1998, 23, 843.
[8] H. Bredereck, G. Simchen, A. A. Santos, Liebigs Ann. Chem. 1972,
766, 73.
C
14H15ClN4OS (322.0655).– MS: m/z = 322.0655.
[9] R.M. Williams, Synthesis of Optically Active α-Amino Acids, Per-
gamon, Elmsford, NY, 1989, pp. 208–229.
Biological Methods
[10] M.H. Jung, J.G. Park, B.S. Ryu, K.W. Cho, J. Heterocycl. Chem. 1999,
36, 429–434.
Receptor Binding Assay
[11] D. L. Dehaven-Hudkins, J. F. Stubbins, R. L. Hudkins, Eur. J. Phar-
macol. 1993, 231, 485–488.
Binding of compounds to muscarinic M1 receptor (M1) was performed by
the radioligand binding assay as described previously [11,12]. Binding affinity
was determined indirectly by the ability of compound to compete with 1 nM
[3H]-N-methylscopolamine (NMS) in the suspension of cloned human M1
(h-1M) expressed in CHO cells (Biosignal). Nonspecific binding was evalu-
ated by the inclusion of 1 µM atropine in a separate set of samples. Each
[12] J. R. Farrar, W. Hoss, R. M. Herndon, M. Kuzmiak, J. Neurosci. 1985,
5, 1083–1089.
Received: November 8, 1999 [FP437]
Arch. Pharm. Pharm. Med. Chem. 333, 113–117 (2000)