Microwave-assisted from synthesis of 2-arylamino-2-imidazolines on a solid support

Article abstract of DOI:10.1002/hc.20081

An efficient synthesis of 2-arylamino-2-imidazolines from dimethyl N-aryldithioimidocarbonates and ethylenediamine on solid support under microwave irradiation has been developed. The reaction time has been reduced from hours to minutes with improved yiel

Full text of DOI:10.1002/hc.20081

Heteroatom Chemistry
Volume 16, Number 2, 2005
Microwave-Assisted from Synthesis
of 2-Arylamino-2-Imidazolines
on a Solid Support
Murat Genc and Su¨leyman Servi
Department of Chemistry, Faculty of Science and Arts, Firat University, Elazig, Turkey
Received 14 October 2004; revised 11 November 2004
Alzheimer’s disease as well as Huntington’s chorea.
ABSTRACT: An efficient synthesis of 2-arylamino-2-
imidazolines from dimethyl N-aryldithioimidocarbo-
nates and ethylenediamine on solid support under
microwave irradiation has been developed. The reac-
tion time has been reduced from hours to minutes
with improved yields as compared to conventional
heating. Their piperidin-4-ylmethyl and morpholin-
4-ylmethyl derivatives were synthesized by treat-
ment with formaldehyde and piperidine or morpho-
Moreover, previous reports demonstrated that syn-
thetic imidazolines act either as inhibitors of ꢀ2-
mediated events in platelets or inducers of platelet
activation. The prototypical agents in the series of
2-arylamino-2-imidazolines are clonidine and mox-
onidine that contain aminoimidazoline structure,
shown ꢀ1 and ꢀ2 adrenoceptor activities, and more
specially phentolamine, which contains an imidazo-
line ring, is a known ꢀ1-adrenergic antagonist [3–5].
Microwave-assisted organic synthesis has also
received a great deal of recent attention due to
shorter reaction times, minimization of reaction
by-products, increased yields, and in many cases
solvent-free conditions. The combination of solvent-
free conditions and MW irradiation leads to large
reductions in reaction times, enhancements in con-
versions, sometimes in selectivity, with several ad-
vantages of the eco-friendly approach. The short re-
action times and expanded reaction range that is
offered by microwave-assisted organic synthesis are
suited to the increased demands in industry. In par-
ticular, there is a requirement in the pharmaceuti-
cal industry for a higher number of novel chemical
entities to be produced, which requires chemists to
employ a number of resources to reduce the time for
the production of compounds [6–8].
ꢀ
C
line.
2005 Wiley Periodicals, Inc. Heteroatom Chem
16:142–147, 2005; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20081
INTRODUCTION
2-Arylamino-2-imidazoline compounds have an in-
teresting chemistry [1,2], and they are effective phar-
macophores in medicinal chemistry. The imidazo-
lines class of drug interacting with adrenergic and
imidazoline receptors is known to mediate a vari-
ety of biological actions including lowering blood
pressure, sedation, anxiety reduction, analgesia, hy-
pothermia, decreased salivary secretion, and mydri-
asis. Imidazoline I2 receptors are widely distributed
in the body and brain of different species including
humans. Functionally, these receptors have been im-
plicated in a variety of disease states such as psychi-
atric disorders, opiate withdrawal Parkinson’s, and
The aim of this work is to demonstrate the ad-
vantages obtained by the use of microwave irradia-
tion in the synthesis of 2-arylamino-2-imidazolines
using the same precursors of the classical method.
The present new method of the formation of 2-aryl-
amino-2-imidazolines under microwave irradiation
Correspondence to: S. Servi; e-mail: sservi@firat.edu.tr.
2005 Wiley Periodicals, Inc.
c
ꢀ
142

Microwave-Assisted Rapid Synthesis of 2-Arylamino-2-Imidazolines on a Solid-Support 143
offers several advantages: faster reaction rates, fewer
yields of reaction are not very high and the reactions
involve generally long process.
by-products, high yields, less expensive equipment,
while the classical method of formation of 2-
arylamino-2-imidazolines involves a long process.
The synthetic route is depicted in Scheme 1.
Dimethyl N-aryldithioimidocarbonates (2a–j) were
synthesized from carbon disulfide, aromatic amine,
and methyl iodide in the presence of concen-
trated aqueous NaOH. Synthesis of 2-arylamino-2-
imidazolines 3a–j carried out both by conventional
heating and by microwave irradiation. Piperidine-
4-yl methyl 5g,h and morpholine-4-yl methyl 4h
derivatives were synthesized by treatment with
piperidine or morpholine and formaldehyde for the
first time. Elemental analysis, IR and 1H NMR
spectra of products clearly indicated formation of
the products Table 1 shows yields and reaction
time by the microwave irradiation and conventional
methods.
Some methods for microwave-assisted solid sup-
port synthesis of substituted imidazoles and their
derivatives are available in the literature [19,20],
but not for of 2-arylamino-2-imidazolines. In this
work, we report the microwave-assisted synthe-
sis of several new 2-arylamino-2-imidazolines on
silica gel as solid support. Silica gel is a very
poor conductor of heat, but a very efficient mi-
crowave adsorbent, resulting in turn in a very rapid
and homogeneous heating. Consequently, silica gel
RESULTS AND DISCUSSION
A number of methods to synthesize 2-arylamino-
2-imidazolines from the corresponding aromatic
amines have been reported in the literature. The
most used methods in the last years are as follow:
(a) Reaction of an aromatic amine with 2-methyl-
thio-2-imidazoline in the presence of pyridine or
toluene (reaction time 2–9 h) [9,10]; (b) a three-
step protocol involving the conversion of an amine
into the isothiocyanate, then treatment of the isoth-
iocyanate with ethylenediamine followed by a cy-
clization using mercuric oxide or acetate to form
the 2-arylamino-2-imidazoline (reaction time 2–5 h)
[11,12]; (c) reaction of aromatic primary amine with
an imidazoline sulfonic acid (reaction time 24–72 h)
[13]; (d) reaction of 2-chloro-2-imidazoline with
amine compounds (reaction time 2–12 h) [14,15];
(e) 2-arylamino-2-imidazolines such as clonidine and
its derivatives were prepared by reaction of dimethyl
N-aryldithioimidocarbonates with ethylenediamine
(reaction time 8 h) [16–18]. In all these methods,
SCHEME 1 (i) 0◦C, DMF, (ii) microwave irradiation, 850 W, silica jel, (iii) DMF, 110◦C, (iv) formaldehyde (35%), morpholine,
room temperature, and (v) formaldehyde (35%), piperidine, room temperature.

144 Genc and Servi
1
TABLE 1 Time Required (min) and Yields (%) of 2-
(C N stretching); 775 (SCH3 stretching). H-NMR
Arylamino-2-imidazolines Prepared
(CHCl3-d, 90 MHz): δ 2.62 (s, 6H, SCH3), 7.4 (s, 5H,
Ar-H). Anal. Calcd. for C9H11NS2 (197): C, 54.78; H,
5.62; N, 7.10; S, 32.49. Found: C, 55.42; H, 5.79; N,
7.35; S, 31.53%.
Time
Microwave
Yield
Microwave
Thermal
Thermal
3a
3b
3c
3d
3e
3f
3g
3h
3i
450
480
420
420
510
510
480
510
540
510
3.0
3.5
3.0
3.5
3.5
4.0
3.5
3.5
4.5
3.5
63
71
65
68
51
46
66
57
44
66
82
91
87
78
69
72
79
74
68
81
Dimethyl N-(4-chlorophenyl)dithioimidocarbo-
nate 2b. Yellowish crystal, yield 71%, mp 110–
112◦C (ethanol); IR (KBr) υmax: 2932 (aliphatic
C H stretching), 1617 (C N stretching), 815 (SCH3
stretching), 507 (C CI). 1H-NMR (CHCl3-d, 200
MHz): δ 2.46 (s, 6H, SCH3), 6.74–7.12 (m, 4H, Ar-H).
Anal. Calcd. for C9H10CINS2: (231): C, 46.64; H, 4.35;
N, 6.04; S, 27.67. Found: C, 45.24; H, 4.50; N, 6.27;
S, 28.56%.
3j
Dimethyl N-(2-methylphenyl)dithioimidocarbo-
nate 2c. Orange powder, yield 67%, mp 152–153◦C
(ethanol), IR (KBr) υmax: 2924 (aliphatic C H
stretching), 1532 (C N stretching), 1090, 1070
(o-disubstituted benzene), 786 (SCH3 stretching).
1H-NMR (CHCl3-d, 90 MHz): δ 2,29 (s, 3H, CH3),
2.60 (s, 6H, SCH3), 7.29–7.51 (m, 4H, Ar-H). Anal.
calcd. for C10H13NS2 (211): C, 56.83; H, 6.20; N, 6.63;
S, 30.34. Found: C, 55.98; H, 6.17; N, 6.53; S, 30.42%.
displays very strong specific microwave effects, with
significant improvements in temperature homogene-
ity and heating rates, enabling faster reactions and
less degradation of final products when compared to
classical heating.
EXPERIMENTAL
Aromatic and heteroaromatic amines except 1h–j
were obtained from commercial sources. Melting
points (uncorrected) were determined with a Gal-
lenkamp apparatus. IR spectra were measured on
Dimethyl N-(4-methylphenyl)dithioimidocarbo-
nate 2d. Light brown powder, yield 54%, mp
175–176◦C (ethanol), IR (KBr) υmax: 2921 aliphatic
C H stretching), 1537 (C N stretching), 1100,
1030, and 820 (p-disubstituted benzene), 765 (SCH3
stretching). 1H-NMR (CHCl3-d, 90 MHz): δ, 2.24
(s, 3H, CH3), 2.50 (s, 6H, SCH3), 7.21–7.44 (s, 4H,
Ar-H). Anal. Calcd. for C10H13NS2 (211): C, 56.83; H,
6.20; N, 6.63; S, 30.34. Found: C, 56.65; H, 6.38; N,
6.23; S, 30.57%.
1
a Mattson model FT-IR spectrometer, and H spec-
tra were measured on FX 90Q JEOL and 200 MHz
Bruker AC instruments. Chemical shift values (δ) are
reported in ppm relative to TMS. Elemental analysis
results are within 0.4% of the calculated value.
General Procedure for 2a–j
To a solution of aromatic (or heteroaromatic) amine
(0.1 mol) in DMF (75 mL), aqueous 20 M sodium hy-
droxide (5.5 mL, 0.11 mol) was added with stirring at
room temperature. After 10 min carbon disulfide (3.3
mL, d: 1.26 g cm−3, 0.055 mol) was added and stir-
ring was continued for 30 min. Then aqueous 20 M
sodium hydroxide (3 mL, 0.06 mol) and carbon disul-
phide (1.8 mL, 0.0275 mol) were added. This opera-
tion was finally repeated 10 min later. After 30 min
the reaction was placed in an ice bath, methyl iodide
(12.5 mL, d: 2.28 g cm−3, 0.2 mol) was added drop-
wise and stirring was continued for 2 h. The mix-
ture was then poured into ice-cooled water and the
precipitate thus obtained was filtered, washed with
water, dried and recrystallized from ethanol.
Dimethyl N-(1,3-thiazole-2-yl)dithioimidocarbo-
nates 2e. Light brown powder, yield 61%, mp 194–
195◦C (ethanol), IR (KBr) υmax: 3092 (aromatic
C H stretching), 2903 (aliphatic C H stretching),
1640 (C C stretching), 1550 (C N stretching), 1530
(Ar-NO2 asymmetric stretching) and 1350 (sym-
metric stretching), 827 (S CH3 stretching).1H-NMR
(DMSO-d6, 90 MHz): δ 2.88 (s, 6H, SCH3), 7.92 (d,
1H, thiazole ring proton). 8.18 (d, 1H, thiazole ring
proton): Anal. Calcd. for C6H8N2S3 (204): C, 35.27;
H, 3.95; N, 13.71; S, 47.08. Found: C, 35.59; H, 4.11;
N, 13.44; S, 47.96%.
Dimethyl N-(5-nitro-1,3-thiazol-2-yl)-dithioimi-
docarbonates 2f. Yellow powder, yield 59%, mp
174–175◦C (ethanol), IR (KBr) υmax: 3095 (aromatic
C H stretching), 2979–2930 (aliphatic C H stretch-
ing), 1678 (C C stretching), 1621 (C N stretching),
Dimethyl N-(phenyl)dithioimidocarbonate 2a.
Yellow crystal, yield 64%, mp 92–93◦C (ethanol); IR
(KBr) υmax: 2935 (aliphatic C H stretching), 1597

Microwave-Assisted Rapid Synthesis of 2-Arylamino-2-Imidazolines on a Solid-Support 145
diamine (5.4 mL, d: 0.897 g cm−3, 0.08 mol) in DMF
(15 mL) with stirring at room temperature. The reac-
tion mixture was refluxed at 110◦C for approximate
6–8 h, cooled, then added to ice-cold water. The re-
sulting solid was washed with water, dried. The crude
products were purified by crystallization from suit-
able solvents.
1530 (Ar-NO2 asymmetric stretching) and 1350
(symmetric stretching), 841 (S CH3 stretching).
1H-NMR (CHCl3-d, 90 MHz): δ: 2.65 (s, 6H, SCH3),
8.36 (s, 1H, thiazole ring proton). Anal. Calcd. for
C6H7N3O2S3 (249): C, 28.90; H, 2.83; N, 16.85; S
38.58. Found: C, 28.39; H, 3.06; N, 15.34; S, 38.79%.
Dimethyl N-(1,3-benzothiazol-2-yl)dithioimido-
carbonate 2g. Yield 69%, yellowish powder, mp
101–102◦C (ethanol); IR (KBr) υmax: 2995 (aliphatic
C H stretching), 1592 (C C stretching), 1510
Microwave Irradiation Method. A mixture of
2a–j (10 mmol) and ethylenediamine (0.7 mL,
d: 0.897 g cm−3, 10 mmol), was stirred a few
minutes with 3 g of silica gel. The mixture was
irradiated in a domestic microwave oven at 850 W
for approximately 3.0–4.5 min. The temperature
was measured at the end of MW irradiation. The
temperatures were obtained around 140–145◦C for
all of the compounds. The mixture was allowed to
cool, then the product was extracted with 4 × 25 mL
methanol/ acetonitrile/chloroform (2/2/1) washed
with distilled water (2 × 10 mL). The organic phase
was separated, and the aqueous phase extracted
with dichloromethane (2 × 5 mL). The combined
organics were dried over anhydrous sodium sul-
fate, filtered. The solvents were removed by rotary
evaporation. The crude products were purified by
crystallization from suitable solvents.
1
(C N stretching), 833 (S CH3 stretching). H-NMR
(CHCl3-d, 90 MHz): δ 2.59 (s, 6H, SCH3), 6.90–7.30
(m, 2H, Ar-H), 7.50–7.86 (2H, m, Ar-H). Anal. Calcd.
for C10H10N2S3 (254): C, 47.21; H, 3.96; N, 11.01; S
37.81. Found: C, 48.39; H, 4.06; N, 11.34; S 38.77%.
Dimethyl N-(5-phenyl-[1,3,4]thiadiazol-2-yl)di-
thioimidocarbonate 2h. Orange powder, yield
62%, mp 111–113◦C (ethanol), IR (KBr) υmax: 2968
(aliphatic C H stretching), 1619 (C C stretching),
1578 and 1537 (C N stretching), 751 (S CH3
1
stretching). H-NMR(CHCl3-d, 90 MHz) δ 2.64 (s,
6H, SCH3), 7.47–7.99 (m, 5H, Ar-H), Anal. Calcd.
for C11H11N3S3 (281): C, 46.95; H, 3.94; N, 14.93; S,
34.18. Found: C, 46.65; H, 3.38; N, 14.23; S, 34.37%.
Dimethyl N-{5-(4-nitrophenyl)[1,3,4]thiadiazol-
2-yl}dithioimidocarbonates 2i. Yield 55%; orange
N-(phenyl)-N-(4,5-dihydro-1H-imidazol-2-yl)-
amine 3a. White powder, mp 115–116◦C (ethanol),
IR (KBr) υmax: 3277 (imidazoline N H stretching),
3257 (N H stretching), 1660 (C N stretching), 1537
powder, mp 250–251◦C (ethanol), IR (KBr) υmax
:
2930–2900 (aliphatic C H stretching), 1633 (C C
stretching), 1592 (C N stretching), 1510 (Ar-
NO2 asymmetric stretching) and 1349 (symmet-
ric stretching), 846 (S CH3 stretching). 1H-NMR
(CHCl3-d, 90 MHz) δ: 2.48 (s, 6H, SCH3), 8.31–8.52
(m, 4H, Ar-H), Anal. Calcd. for C11H10N4O2S3 (326):
C, 40.48; H, 3.09; N, 17.16; S, 27.47. Found: C, 39.56;
H, 3.32; N, 17.19; S, 28.09%.
1
(N H bending). H NMR (DMSO-d6, 200 MHz) δ:
3.48 (s, 1H, NH), 3.73 (s, 4H, imidazoline CH2),
6.30 (broad peak, 1H, imidazoline NH), 7.12–8.20
(m, 5H, Ar-H). Anal. Calcd. for C9H11N3 (161): C,
67.06; H, 6.88; N, 26.07. Found: C, 68.11; H, 7.24; N,
26.83%.
N-(4-Chlorophenyl)-N-(4,5-dihydro-1H-imidazol-
2-yl)amine 3b. White powder, mp 147–148◦C
(ethanol), IR (KBr) υmax: 3284 (imidazoline N H
stretching), 3245 (N H stretching), 1681 (C N
Dimethyl N-[5-(2,4,6-trimethylbenzyl)-1,3-thia-
zole-2-yl]dithioimidocarbonates
2j. Yield
74%,
orange power, mp 91–92◦C (ethanol), IR (KBr)
υmax: 2920 and 2855 (aliphatic C H stretchings),
1612 (C C stretching), 1523 (C N stretching), 756
(S CH3 stretching). 1H-NMR (CHCl3-d, 90 MHz)
δ: 2.26 (s, 9H, mesitylene CH3), 2,58 (s, 6H, SCH3),
3,92 (s, 2H, aliphatic CH2), 6,21 (s, 1H, thiazole ring
proton), 6.87–7.26 (m, 2H, Ar-H), Anal. Calcd. for
C16H20N2S3 (336): C, 57.10; H, 5.99; N, 8.32; S, 28.58.
Found: C, 58.12; H, 5.19; N, 8.45; S, 28.97%.
1
stretching), 1594 (N H bending). H NMR (DMSO-
d6, 200 MHz): δ 3.67 (s, 1H, NH), 3.76 (s, 4H, imida-
zoline CH2), 6.24 (broad peak, 1H, imidazoline NH),
7.05–7.40 (m, 4H, Ar-H). Anal. Calcd. for C9H10ClN3
(195): C, 55.25; H, 5.15; N, 21.48. Found: C, 56.13;
H, 5.74; N, 22.05%.
N-(2-Methylphenyl)-N-(4,5-dihydro-1H-imidazol-
2-yl)amine 3c. Light brown powder, mp 188–191◦C
(THF), IR (KBr) υmax: 3382 and 3252 (N H stretch-
ing), 1660 (C C stretching), 1523 (C N stretching),
1498 (N H bending); 1H NMR (DMSO-d6, 90 MHz):
δ 2.01 (s, 1H, NH), 2.24 (s, 3H, CH3), 3.74 (s, 4H,
General Procedure for 3a–j
Thermal Method. A solution of 2a–j (0.04 mol)
in DMF (15 mL) was added to a solution of ethylene-

146 Genc and Servi
1
imidazoline CH2), 6.44 (broad peak, 1H, imidazoline
NH), 7.71 (m, 4H, Ar-H), Anal. Calcd. for C10H13N3
(175): C, 68.54; H, 7.48; N, 23.98; Found: C, 67.93;
H, 7.96; N, 24.41.
stretching), 1443 (N H bending); H NMR (DMSO-
d6, 90 MHz): δ 3.76 (s, 4H, imidazoline CH2), 7.45
(s, 5H, Ar-H); 7.55 (s, 2H, NH). Anal. Calcd. for
C11H11N5S (245): C, 53.86; H, 4.52; N, 28.56; S,
13.07. Found: C, 54.03; H, 4.66; N, 28.41; S, 13.65%.
N-(4-methylphenyl)-N-(4,5-dihydro-1H-imidazol-
2-yl)amine 3d. Light grey powder, mp 190–191◦C
(ethanol), IR (KBr) υmax: 3364 (imidazoline N H
stretching), 3249 (N H stretching), 1486 (N H
N-[5-(4-nitrophenyl)-[1,3,4]-thiadiazole-2-yl]-
N-(4,5-dihydro-1H-imidazol-2-yl)amine 3i. Yellow
powder, mp 239–240◦C (ethanol), IR (KBr) υmax: 3396
and 3218 (N H stretching), 1626 (C C stretching),
1538 (C N stretching), 1508 (Ar-NO2 asymmetric
stretching), 1465 (N H bending) 1350 (Ar-NO2 sym-
1
bending). H NMR (DMSO-d6, 90 MHz): δ 3.63 (s,
1H, NH), 2.38 (s, 3H, CH3), 3.77 (s, 4H, imidazoline
CH2), 6.31 (broad peak, 1H, imidazoline NH), 7.71
(m, 4H, Ar-H), Anal. Calcd. for C10H13N3 (175): C,
68.54; H, 7.48; N, 23.98; Found: C, 67.74; H, 7.36; N,
24.11%
1
metric stretching), H NMR (DMSO-d6, 90 MHz):
δ 3.58 (s, 4H, imidazoline CH2), 7.53–8.29 (m, 4H,
Ar-H), 8.09 (s, 2H, NH) Anal. Calcd. for C11H10N6O2S
(290): C, 45.51; H, 3.47; N, 28.95; S, 11.05. Found:
C, 45.11; H, 3.70; N, 28.56; S, 11.55%.
N-(1,3-thiazol-2-yl)-N-(4,5-dihydro-1H-imidazol-
2-yl)amine 3e. Yellow powder, mp 245–246◦C
(ethanol), IR (KBr) υmax: 3289 (imidazoline N H
stretching), 3219 (N H stretching), 1609 (C N
N-[5-(2,4,6-trimethylbenzyl)-1,3-thiazole-2-yl]-
N-(4,5-dihydro-1H-imidazole-2-yl)amine 3j. Light
grey powder, mp 172–174◦C (toluene), IR (KBr) υmax
:
1
stretching), 1531 (N H bending). H NMR (DMSO-
3382 and 3372 (N H stretching), 2923 (C H stretch-
ing), 1626 (C C stretching), 1532 (C N stretching),
d6, 90 MHz): δ 3.69 (s, 4H, imidazoline CH2), 7.21 (d,
1H, thiazole ring proton), 7.57 (d, 1H, thiazole ring
proton), 8.48 (s, 2H, NH), Anal. Calcd. for C6H8N4S
(168): C, 42.84; H, 4.79; N, 33.31; S,19.06. Found: C,
43.23; H, 4.55; N, 34.06; S, 19.37%.
1
1471 (N H bending). H NMR (DMSO-d6, 90 MHz)
δ 2.15 (s, 2H, NH), 2.26 (s, 9H, 3 × CH3), 3.66 (s, 4H,
imidazoline CH2), 3.91 (s, 2H, aliphatic CH2), 5.76
(s, 1H, thiazole ring proton), 6.87 (m, 2H, Ar-H),
Anal. Calcd. for C16H20N4S (300): C, 63.97; H, 6.71;
N, 18.65; S, 10.67. Found: C, 63.85; H, 6.56; N, 18.34;
S, 10.07%.
N-(5-nitro-1,3-thiazol-2-yl)-N-(4,5-dihydro-1H-
imidazol-2-yl)amine 3f. White powder, mp 133–
135◦C (chloroform), IR (KBr) υmax: 3358 and 3317
(N H stretching), 1681 (C C stretching), 1619 (C N
stretching), 1544 (Ar-NO2 asymmetric stretching),
1465 (N H bending) 1359 (Ar-NO2 symmetric
General Procedure for 4 and 5
A solution of 3g,h (0.01 mol) in methanol (20 mL)
was stirred at room temperature for 2 h with aque-
ous formaldehyde (35%; 0.015 mol) and morpholine
(0.9 mL, d: 1 g cm−3, 0.01 mol or 1 mL, d: 0.86 g cm−3
for piperidine). The solvent was removed on a rotary
evaporator. The residue was mixed with methanol,
and the precipitate formed was filtered and then re-
crystallized from chloroform.
1
stretching), H NMR (DMSO-d6, 90 MHz): δ 3.66 (s,
4H, imidazoline CH2), 8.19 (s, 2H, NH), 8.35 (s, 1H,
thiazole ring proton), Anal. Calcd. for C6H7N5O2S
(213): C, 33.80; H, 3.31; N, 32.85; S, 15.04. Found:
C, 34.19; H, 3.59; N, 33.21; S, 15.19%.
N-(1,3-Benzothiazol-2-yl)-N-(4,5-dihydro-1H-
imidazol-2-yl)amine 3g. White powder, mp 131–
132◦C (ethanol), IR (KBr) υmax: 3281 (imidazoline
N H stretching), 3220 (N H stretching), 1611
(C N stretching), 1528 (N H bending). 1H NMR
(DMSO-d6, 200 MHz): δ 1.74 (s, 1H, NH), 3.78 (s,
4H, imidazoline CH2), 7.09–7.64 (m, 4H, Ar-H), 8.01
(broad peak, 1H, imidazoline NH). Anal. Calcd.
for C10H10N4S (218): C, 55.02; H, 4.62; N, 25.37; S,
14.69. Found: C, 55.63; H, 4.96; N, 26.41; S, 15.19%.
N-(5-Phenyl-[1,3,4]thiadiazol-2-yl)-N-[1-(morpho-
lin-4-ylmethyl)-4,5-dihydro-1H-imidazol-2-yl]amine
4h. Yellow crystal, yield 59%, mp 127–128◦C
(chloroform), IR (KBr) υmax: 3305 (imidazoline
N H stretching), 1588 (C N stretching), 1145 (C N
stretching), 1114 (cyclic ether C O C stretching),
1H NMR (CHCl3-d, 90 MHz) δ: 2.57–2.62 (s, 4H,
morpholine ring CH2 N CH protons), 3.64–3.74 (s,
2
8H, morpholine ring CH2 protons and imidazoline
ring protons), 4.11 (s, 2H, NCH2N), 7.49–7.89 (m,
5H, Ar-H), 8.47 (broad peak, 1H, NH), Anal. Calcd.
for C16H20 N6OS (344): C, 55.79; H, 5.85; N, 24.40; S,
9.31. Found: C, 55.35; H, 4.86; N, 23.96; S, 8.79%.
N-(5-Phenyl-[1,3,4]-thiadiazol-2-yl)-N-(4,5-di-
hydro-1H-imidazol-2-yl)amine 3h. mp 192–194◦C
(toluene), IR (KBr) υmax: 3317 and 3297 (N H
stretching), 1614 (C C stretching), 1528 (C N

Microwave-Assisted Rapid Synthesis of 2-Arylamino-2-Imidazolines on a Solid-Support 147
N-(1,3-Benzothiazol-2-yl)-N-[1-(piperidin-4-yl-
REFERENCES
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White crystal, yield 67%, mp 158–159◦C (chlo-
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stretching), 1576 (C N stretching), 1137 (C N
stretching), 1H NMR (CHCl3-d, 90 MHz) δ 1.49
(s, 6H, piperidine ring protons), 2.57–2.62 (s, 4H,
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CH2 N CH protons), 3.64 (s, 4H, imidazoline ring
2
protons), 4.08 (s, 2H, NCH2N), 7.41–7.88 (5H, m,
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Found: C, 59.11; H, 6.87; N, 24.21; S, 9.60%.
CONCLUSION
In conclusion, we have described a rapid and highly
efficient method for the synthesis of 2-arylamino-
2-imidazolines starting from dimethyl N-aryldithio-
imidocarbonates on solid support microwave irradi-
ation reaction conditions.
ACKNOWLEDGMENT
We are indebted to the Firat University Research
¨
Foundation (FUBAP 1055) for financial support of
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