Synthesis of Some New Thiazolo[3,2-a]pyrimidine Derivatives and Their Applications as Disperse Dyes

Article abstract of DOI:10.1002/jhet.3470

A series of novel thiazolo[3,2-a]pyrimidine derivatives were synthesized by using β-ketoanilides 1a–c as starting materials and as key intermediates for preparation of new pyrimidinecompounds 3a–e and fused heterocyclic pyrimidine derivatives 5a–c. The ne

Full text of DOI:10.1002/jhet.3470

Month 2019 Synthesis of Some New Thiazolo[3,2-a]pyrimidine Derivatives and Their
Applications as Disperse Dyes
Fathi El-Taweel,b Shereen Abdeldayema and Abeer Abou Elfarhb
a
*
Tarek Abou Elmaaty,
aDepartment of Textile Printing, Dyeing and Finishing, Faculty of Applied Arts, Damietta University, Damietta 34512,
Egypt
bDepartment of Chemistry, Faculty of Science (New Damietta), Damietta University, Damietta 34517, Egypt
*E-mail: tasaid@du.edu.eg
Received September 2, 2018
DOI 10.1002/jhet.3470
Published online 00 Month 2019 in Wiley Online Library (wileyonlinelibrary.com).
A series of novel thiazolo[3,2-a]pyrimidine derivatives were synthesized by using β-ketoanilides 1a–c as
starting materials and as key intermediates for preparation of new pyrimidinecompounds 3a–e and fused het-
erocyclic pyrimidine derivatives 5a–c. The new compounds were transformed to disperse dyes 6a,b and 7.
The chemical structures were elucidated by spectroscopic and elemental analyses and found to be in good
agreement with the proposed structures. The versatility of compounds 6a,b and 7 for textile dyeing as dis-
perse dyes was reported. The synthesized dyes were applied to polyester fabrics by using high temperature
dyeing method at 120°C. The dye uptake expressed as color strength (k/s) of the dyed samples has been mea-
sured. Moreover, the color strength was examined in detail. In addition, the position of color in CIELAB co-
ordinates (L*, a*, b*, h, and C*) was assessed. The color fastness of the dyed samples gave excellent results
for washing and rubbing; however, the light fastness was moderate. Raman spectra of dyed samples unequiv-
ocally excluded ring dyeing and found to match with the proposed structures.
J. Heterocyclic Chem., 00, 00 (2019).
INTRODUCTION
of fused heterocyclic pyrimidine derivatives [25–30].
Aryl-azo and hetaryl-azo coloring matters have been in
use since prehistoric times [31]. The interest in such
coloring materials is due to the fact that many derivatives
were found useful in the field of material science and
applied chemistry [32]. For example, many such azo dyes
have been extensively used as dyes in various fields such
as dyeing of textile fibers, colored plastics, biological-
medical studies, and advanced applications in organic
synthesis [33]. Recently, arylazo derivatives of various
heterocyclic systems have been receiving more research
attention by organic chemists [34] and dye manufacturers
[35]. It is worth mentioning that azo-hydrazone
tautomerism is of importance not only to dyestuff
β-Ketoanilides are versatile reagents that have been
extensively utilized in heterocyclic synthesis [1–16]. In
this work, the prepared heterocycles are proved to be
interesting for their potentiality as biodegradable
agrochemicals [7], pharmaceuticals [3,7], as non-peptide
HIV [6], protease inhibitors, anti-schistosomal agents
[3,4], and intermediates for the manufacture of dyestuffs.
In the past few years, we have been involved in a
program aiming to develop new simple routes for the
synthesis of different heterocyclic compounds of interest
to be evaluated as disperse dyestuff [17–24]. Several
synthetic approaches have been reported for the synthesis
© 2019 Wiley Periodicals, Inc.

T. Abou Elmaaty, F. El-Taweel, S. Abdeldayem, and A. Abou Elfarh
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Scheme 2. Synthesis of thiazolo[3,2-a]pyrimidine 5a–c and
arylazothiazolo[3,2-a]pyrimidines derivatives 6a–b.
manufacture but also to other areas of chemistry. Also,
azo-hydrazone tautomers have different tinctorial
strengths (and economics) and different properties, e.g.,
rubbing and washing fastness [36]. From the above and
from the conjunction to previous interest in developing
synthesis of poly functionally substituted hetero
aromatics utilizing readily obtainable and inexpensive
starting components [37–41], we report here on synthesis
of thiazolo[3,2-a]pyrimidine derivatives using β-
ketoanilides 1a–c, aromatic amines, and thiourea 2 as
starting materials and as key intermediates for application
as disperse dyes for dyeing polyester fabrics.
RESULTS AND DISCUSSION
Synthesis and reactions. A mixture of β-ketoanilides
1a–c, aromatic aldehydes, and thiourea 2 was heated
products. Indication of structure 5b is based on the correct
values of elemental analysis and appropriate spectral data
under reflux in ethanol containing
a few drops
1
(IR, H-NMR, and mass spectrum). As an example, the
hydrochloric acid as a catalyst to afford 4-aryl-6-methyl-
2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides
3a–e (Scheme 1). Structure 3a–e was supported by its
analytical and spectral data. As an example, the infrared
spectrum of 3a exhibited bands at 3398 and 3284 cmÀ1
(NH), 1674 cmÀ1 (C═O), and 1236 cmÀ1 (C═S). The
1H-NMR spectrum of 3a showed the singlet signal at
δ = 2.04 ppm due to the methyl group protons, a singlet
signal at δ = 3.68 ppm attributed to the methoxy group
protons, a singlet signal at δ = 5.30 ppm for the H-4
pyrimidine ring proton, multiple signals in the range
δ = 6.67–7.53 ppm for the aromatic protons, a singlet
signal at δ = 8.99 ppm due to the hydroxyl group proton,
and three singlet signals at δ = 9.32, 9.68, and 9.90 ppm
due to three NH protons. The mass spectrometric
measurements of compound 3a gave an additional
confirmation for the proposed structure that showed the
molecular ion peak at m/z 369 corresponding to (M+,
29.0%). Cyclo-condensation of 4-aryl-6-methyl-2-thioxo-
1,2,3,4-tetrahydropyrimidine-5-carboxamides 3a–e with
ethyl chloroacetate in refluxing ethanol catalyzed by
sodium acetate gave thiazolo[3,2-a]pyrimidine derivatives
5a–c (Scheme 2). Compounds 5a–c were confirmed on
the basis of the correct analytical and spectral data of the
IR spectrum of 5b exhibited the bands at 3373 cmÀ1
(NH) and 1730 and 1649 cmÀ1 (C═O). The 1H-NMR
spectrum of 5b revealed a singlet signal at δ = 2.05 ppm
due to the methyl group protons, doublet doublet signals
in the range δ = 4.05–4.15 ppm for CH2 protons at
J = 18 Hz, a singlet signal at δ = 5.30 for the H-4
pyrimidine ring proton, a single singlet at δ = 5.97 ppm
for (O─CH2O─) protons, multiple signals in the range
δ = 6.71–7.54 ppm due to the aromatic protons, and a
singlet signal at δ = 9.70 ppm for NH proton. The
mass spectrometric measurements of compound 5b gave
an additional confirmation for its structure that
showed the molecular ion peak at m/z 407 corresponding
to (M+, 12.09%).
Compounds 5a–c were coupled readily with
aryldiazonium chlorides to yield the arylazothiazolo[3,2-
a]pyrimidines 6a,b in excellent yields (Scheme 2).
Elucidation of structure 6a was based on the
correct values of elemental analysis and appropriate
1
spectral data (IR, H-NMR, and mass spectrum). The IR
spectrum of 6a gave the bands at 3467 cmÀ1 (NH) and
1
1712 and 1651 cmÀ1 (C═O). The H-NMR spectrum of
6a showed a singlet signal at δ = 2.12 ppm due to the
methyl group protons, a singlet signal at δ = 5.96 ppm
for the H-4 pyrimidine ring proton, a singlet signal
at δ = 5.99 ppm for (O─CH2O─) protons, multiple
signals in the range δ = 6.72–7.72 ppm due to the
aromatic protons, and two singlet signals at δ = 9.97 and
12.25 ppm for two NH protons. The mass spectrometric
measurements of compound 6a gave an additional
confirmation for its structure that showed the molecular
ion peak at m/z 545 corresponding to (M+, 14.17%).
Also, 4-benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid thiazol-2-ylamide
Scheme
1. Synthesis
of
4-aryl-6-methyl-2-thioxo-1,2,3,4-
tetrahydropyrimidine-5-carboxamides 3a–e.
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Synthesis of Some New Thiazolo[3,2-a]pyrimidine Derivatives and Their
Applications as Disperse Dyes
3e was reacted with o-chlorobenzene diazonium chloride
to afford 4-benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-
1,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid [5-(2-
chloro-phenylazo)-thiazol-2-yl]-amide 7 (Scheme 3). The
formed product was found in a full agreement with
assigned structure based on elemental analysis and
spectral data that confirmed the formation of structure 7.
The IR spectrum of 7 gave 3240 and 3174 cmÀ1 (NH)
and 1658 cmÀ1 (C═O). The 1H-NMR spectrum of 7
showed a singlet signal at δ = 2.13 ppm for the methyl
group protons, a singlet signal at δ = 5.45 ppm due to the
forces including Van der Waals forces. Electron-attracting
groups enable stronger Van der Waals forces and
hydrogen bonding with the dyed fabrics that increases
their stability to washing. As shown in Table 1, the
results showed that the dyed fabrics have excellent
fastness to rubbing (wet, dry) especially wet rubbing
fastness. As for the light fastness of the synthesized dyes
on polyester, it is significantly affected by the nature of
substituent in the diazo component. Al-Etaibi et al. [43]
suggested that fading of azo dyes is mainly
a
consequence of decomposition of the ─N═N─ moiety by
oxidation, reduction, or photolysis. The rates of these
processes should be sensitive to the chemical structure of
the dye, the type of substrate, and treatment conditions.
Because the dyed substrate employed in this study is
polyester fabrics (i.e., non-proteinic), the fading process
likely occurs by oxidation [44]. The ease of oxidation of
azo linkages should be a function of electron density.
Therefore, electron-donating substituent on this moiety
should increase the fading rate. This proposal is in
agreement with the observed results (Table 1) that
demonstrated the decrease of light fastness to 1–3 caused
by the presence of a methyl group in dyestuff under study.
Color assessment. The colors of dyestuff under study
on polyester fabrics were expressed in terms of CIELAB
values (Table 2), and the following CIELAB coordinates
were measured by the reflectance spectrometer, where
(L*) values represent color lightness. Chroma (C*) values
represent color purity, hue angle (h) values, which varies
from 0° to 360°, to specify the color related to the
principle colors, (a*) values represent the degree of
redness (positive) and greenness (negative), and (b*)
values represent the degree of yellowness (positive) and
blueness (negative) [45]. As shown in Table 2, dyes 6a,b
and 7 showed good affinity to polyester fabrics through
the satisfactory color yields and accepted values of K/S.
The dyes 6b and 7 were found to be lighter than the
other derivative 6a according to the color lightness values
L*. These results were in line with the previously
reported by Muller on the effect of substituent in the dye
structure and hue [46].
H-4 pyrimidine ring proton,
a single singlet at
δ = 5.97 ppm for (O─CH2O─) protons, multiple signals
in the range δ = 6.70–7.44 ppm for the aromatic protons,
a singlet signal at δ = 7.93 for the C-4 thiazole ring
proton, and three singlet signals at δ = 9.51, 10.13, and
11.90 ppm for three NH protons.
Dyeing and fastness properties. For dyeing polyester
fabrics, in practical terms, only disperse dyes are suitable.
Through their hydrophobic properties, these dyes are
capable of penetrating into the similarly hydrophobic
polyester fiber. The dyes on polyester fabrics were
evaluated in terms of their fastness properties and given in
Table 1 using standard method. Fastness to washing and
rubbing were tested according to the reported methods
[42]. The dyes obtained (6a,b; 7) gave good leveling,
uniformity of coloration, and exhaustion of dye liquor.
The good results of the dyestuff under study on polyester
fabrics might be attributed to the fact that these disperse
dyes are mainly dispersed within the pores in the
polyester fabrics and are held in their places by different
Scheme 3. Synthesis of 4-benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-
1,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid [5-(2-chloro-phenylazo)-
thiazol-2-yl]-amide (7).
Effect of dye concentration. Figure 1 showed that, for
all dyes under study 6a, 6b, and 7, increasing in
concentration of dyestuff from 2% to 6% of the weight of
Table 1
Fastness properties of the synthesized dyes 6a, 6b, and 7 on 100% poly-
ester fabrics.
Table 2
Fastness properties
Optical measurements of dyes 6a, 6b, and 7.
Washing
Rubbing
Light
Dye color
St.
Alt.
Wet
Dry
(100 h)
Dye
L*
a*
b*
C*
h
K/S
6a
6b
7
Yellow
Orange
Yellow
5
5
5
5
5
5
5
5
5
5
5
5
1/2
3
2/3
6a
6b
7
86.56
72.49
81.04
À5.42
26.03
5.43
48.46
48.81
49.27
48.76
55.31
49.57
96.39
61.93
83.71
3.45
3.12
5.19
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the fabric was accompanied by an increase in the dye
uptake expressed as color strength (K/S) values reaching
a maximum at 4% for dyes 6a,b and then went down by
further increase in concentration. This is probably due to
the fact that dye 6a,b has strong saturation in water at
low concentration. In the case of dying with dye 7, the
maximum color strength K/S value was obtained at a 6%
concentration of the dye. This may be attributed to the
fact that more amount of dyes were diffused into fabrics
with increasing dye concentration [47]. It can be
concluded from Figure 1 and the results in Table 2 that
the dispersed dye 7 has good affinity to fabric than others
and the K/S value was increased by increasing the dye
concentration to 6%.
Raman spectra for the dyed samples.
Raman
spectroscopy allows for the detection of dyes used in the
coloration of such samples. Its potential was also
demonstrated for the analysis of textile fibers. For the
fiber dye analysis, Raman spectroscopy plays
a
complementary role that allows for identifying the main
dye used for the impregnation of the fiber. The Raman
technique presents advantages such as its nondestructive
Figure 1. Color strength of synthesized disperse dyes with different concentrations. [Color figure can be viewed at wileyonlinelibrary.com]
Figure 2. Raman spectrum of dyed polyester 6a. [Color figure can be viewed at wileyonlinelibrary.com]
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Month 2019
Synthesis of Some New Thiazolo[3,2-a]pyrimidine Derivatives and Their
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nature, its fast analysis time, and the possibility of
performing microscopic in situ analyses. Here, spectra
were collected in the range of 0 to 4000 cmÀ1. They
were acquired using scan time settings of 50 s for fiber
analysis. Raman data acquisition and data processing
were achieved using Lab Spec 6 spectroscopy suit
software. It can be seen from Figures 2–4 that the
polyester dyed with dye 6a showed signals at δ = 1795,
1626 (C═O), and 3241 and 3403 cmÀ1 (NH), polyester
dyed with dye 6b showed signals at δ = 1787, 1616
Figure 3. Raman spectrum of dyed polyester 6b. [Color figure can be viewed at wileyonlinelibrary.com]
Figure 4. Raman spectrum of dyed polyester 7. [Color figure can be viewed at wileyonlinelibrary.com]
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T. Abou Elmaaty, F. El-Taweel, S. Abdeldayem, and A. Abou Elfarh
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(C═O), 3291 (NH), and 3663 cmÀ1 (OH), and polyester
dyed with dye 7 showed signals at δ = 1249 (C═S), 1737
(C═O), and 3162 and 3343 cmÀ1 (NH).
4-(4-Hydroxy-3-methoxy-phenyl)-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid phenylamide (3a).
Colorless crystals (EtOH); yield 76%; mp 194–196°C; IR
(KBr) νmax cmÀ1: 3398, 3284 (NH), 1674 (C═O), 1236
1
(C═S). MS: m/z 369 (M+, 29.0%). H-NMR (DMSO-d6)
CONCLUSION
(δ, ppm): 2.04 (s, 3H, CH3), 3.68 (s, 3H, OCH3), 5.30
(s,1H, pyrim H-4), 6.67–7.53 (m, 8H, Ar─H), 8.99 (s,
1H, OH), 9.32, 9.68, 9.90 (3s, 3H, 3NH); Anal. Calcd for
C19H19N3O3S (MW: 369.44): C, 61.77; H, 5.18; N,
11.37%. Found: C, 61.54; H, 4.95; N, 11.13%.
4-Benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid phenylamide (3b).
A series of novel thiazolo[3,2-a]pyrimidine derivatives
were synthesized by using β-ketoanilides 3a–c as starting
materials. The synthesized dyes were applied for dyeing
100% polyester fabrics using high temperature dyeing
method at 120°C. The dyed polyester fabrics, displayed
redness to yellowness hues, exhibited excellent fastness
to washing and rubbing fastness properties and moderate
light fastness depending on the amount of dye fixed.
Finally, the synthesized dye 4-benzo[1,3]dioxol-5-yl-6-
methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylic
acid [5-(2-chloro-phenylazo)-thiazol-2-yl]-amide 7 gave the
best results with the fastness for washing, rubbing, and light.
It gave a good affinity to fabric than others, and its dye
uptake expressed as color strength (K/S) value was
increased by increasing the dye concentration.
Colorless crystals (EtOH); yield 79%; mp 160–162°C; IR
(KBr) νmax cmÀ1: 3259, 3005 (NH), 1682 (C═O), 1239
1
(C═S); MS: m/z 367 (M+, 18.60%); H-NMR (DMSO-
d6) (δ, ppm): 2.06 (s, 3H, CH3), 5.30 (s, 1H, pyrim H-4),
5.98 (s, 2H, ─O─CH2O─), 6.71–7.54 (m, 8 H, Ar─H),
9.38, 9.70, 9.98 (3s, 3H, 3NH); Anal. Calcd for
C19H17N3O3S (MW: 367.42): C, 62.11; H, 4.66; N,
11.44%. Found: C, 61.90; H, 4.44; N, 11.21%.
4-(3,4-Dimethoxy-phenyl)-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid phenylamide (3c).
Yellow crystals (EtOH); yield 76%; mp 171–176°C; IR
(KBr) νmax cmÀ1: 3197 (NH), 1649 (C═O), 1263 (C═S);
MS: m/z 383 (M+, 21.99%); 1H-NMR (DMSO-d6) (δ,
ppm): 2.05 (s, 3H, CH3), 3.65, 3.69 (2s, 6H, 2OCH3),
5.34 (s, 1H, pyrim H-4), 6.76–7.54 (m, 8H, Ar─H), 9.37,
9.71, 9.95 (3s, 3H, 3NH); Anal. Calcd for C20H21N3O3S
(MW: 383.46): C, 62.64; H, 5.52; N, 10.96%. Found: C,
EXPERIMENTAL
Melting points were measured on Griffin & George MBF
010T (London) apparatus with model R 134301 and are un-
corrected. Recorded yield corresponds to the pure products.
The infrared spectra were recorded for (KBr) disk on a
Perkin Elmer SP-880 spectrophotometer at Faculty of Sci-
ence, Damietta University, New Damietta, Egypt. The 1H-
NMR spectra were recorded on Delta 2_NMR spectrometer
(500 MHz) in dimethyl sulfoxide (DMSO-d6) as solvent,
using tetramethylsilane as an internal standard, and chemi-
cal shifts are expressed as δ ppm at Mansoura University,
Mansoura, Egypt. Mass spectra were determined on
Finnigan in COS (70 ev) on DSQ instrument model.
The Raman spectra were collected using laser Raman
spectrometer with NRS-4500 model at Faculty of Applied
Arts, Damietta University, Egypt. Elemental analyses
(C, H, and N) were carried out at the Micro-analytical
Center of Cairo University, Giza, Egypt; the results were
found to be in good agreement with the calculated values.
62.45; H, 5.35; N, 10.77%.
4-Benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid (4-methoxy-phenyl)-
amide (3d). Colorless crystals (EtOH/H2O); yield 77%;
mp 239–240°C; IR (KBr) νmax cmÀ1: 3259 (NH), 1685
(C═O), 1230 (C═S); 1H-NMR (DMSO-d6) (δ, ppm):
2.05 (s, 3H, CH3), 3.68 (s, 3H, OCH3), 5.28 (s, 1H,
pyrim H-4), 5.98 (s, 2H, O─CH2O─), 6.70–7.45 (m, 7
H, Ar─H), 9.35, 9.56, 9.94 (3s, 3H, 3NH); Anal. Calcd
for C20H19N3O4S (MW: 397.45): C, 60.44; H, 4.82; N,
10.57%. Found: C, 60.16, H, 4.61; N, 10.36%.
4-Benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-1,2,3,4-
tetrahydro-pyrimidine-5-carboxylic acid thiazol-2-ylamide
(3e).
Colorless crystals (EtOH/DMF); yield 75%; mp
264–266°C; IR (KBr) νmax cmÀ1: 3163 (NH), 1662
(C═O), 1238 (C═S); 1H-NMR (DMSO-d6) (δ, ppm):
2.13 (s, 3H, CH3), 5.45 (s, 1H, pyrim H-4), 5.97 (s, 2H,
O─CH2O─), 6.70–6.80 (m, 3H, Ar─H), 7.44 (s, 1H,
thiazole H-5), 7.93 (s, 1H, thiazole H-4), 9.51, 10.13,
11.90 (3s, 3H, 3NH); Anal. Calcd for C16H14N4O3S2
(MW: 374.44): C, 51.32; H, 3.77; N, 14.96%. Found: C,
51.16; H, 3.69; N, 14.89%.
Synthesis
of
4-aryl-6-methyl-2-thioxo-1,2,3,4-
tetrahydropyrimidine-5-carboxamides (3a–e).
A mixture
of β-ketoanilides 1a–c (0.01 mol), aromatic aldehydes
(0.01 mol), and (1.28 g, 0.01 mol) of thiourea 2 in
ethanol (50 mL) containing few drops of concentrated
HCl was heated under reflux for 5–6 h until the
precipitates were formed. The reaction mixtures were left
to cool at room temperature, and the precipitates formed
were collected by filtration and recrystallized from
suitable solvents to give compounds 3a–e.
Synthesis of thiazolo[3,2-a]pyrimidine derivatives 5a–c.
A mixture of pyrimidinethiones 3a–c (0.01 mol) and ethyl
chloroacetate 4 (0.69 g, 0.01 mol) in the presence of
ethanol and sodium acetate anhydrous was heated under
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Month 2019
Synthesis of Some New Thiazolo[3,2-a]pyrimidine Derivatives and Their
Applications as Disperse Dyes
reflux for 5–6 h, and then, the reaction mixture was left
to cool at room temperature. The solid products formed
after pouring onto ice/water were filtered off and
crystallized from the proper solvents to give the pure
products as 5a–c.
5-(4-Hydroxy-3-methoxy-phenyl)-7-methyl-3-oxo-2,3-
2-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-
ylazo)-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-3-oxo-2,3-
dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic
acid
phenylamide (6b). Orange crystals (xylene); yield 82%;
mp 190–192°C; IR (KBr) νmax cmÀ1: 3390 (NH), 1730,
1
1657 (C═O); H-NMR (DMSO-d6) (δ, ppm): 2.04 (s, 3H,
dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic
phenylamide (5a).
acid
CH3), 2.23 (s, 3 H, CH3), 3.35 (s, 3H, N─CH3), 3.63 (s,
3H, OCH3), 5.94 (s, 1H, pyrim H-4), 6.69–7.54 (m, 8H,
Ar─H), 8.09 (s, 1H, OH), 9.10, 9.89 (2s, 2H, 2NH); Anal.
Calcd for C32H29N7O5S (MW: 623.68): C, 61.62; H,
4.69; N, 15.72%. Found: C, 61.40; H, 4.45; N, 15.44%.
Pale yellow crystals (EtOH); yield
74%; mp 258–259°C; IR (KBr) νmax cmÀ1: 3305 (NH),
1734, 1647 (C═O); 1H-NMR (DMSO-d6) (δ, ppm):
2.05 (s, 3H, CH3), 3.64 (s, 3H, OCH3), 4.07–4.16 (dd,
2H, CH2, J = 17 Hz), 5.95 (s, 1H, pyrim H-4), 6.60–
7.54 (m, 8H, Ar─H), 9.11 (s, 1H, OH), 9.90 (s, 1H,
NH); Anal. Calcd for C21H19N3O4S (MW: 409.4): C,
61.60; H, 4.68; N, 10.26%. Found: C, 61.53; H, 4.55;
Synthesis of 4-benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-
1,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid [5-(2-chloro-
phenylazo)-thiazol-2-yl]-amide (7).
A solution of 4-
benzo[1,3]dioxol-5-yl-6-methyl-2-thioxo-1,2,3,4-tetrahydro-
pyrimidine-5-carboxylic acid thiazol-2-ylamide 3e (0.8 g,
0.01 mol) in ethanol/DMF containing sodium acetate
anhydrous (2 g) was treated with (0.27 g, 0.01 mol) 2-
chlorobenzene diazonium chloride at 0–5°C with
continuous stirring. The reaction mixture was left overnight
in the refrigerator. The precipitate formed was collected by
filtration and recrystallized from EtOH/DMF to give
yellow crystals of 7; yield (80%); mp 252–254°C; IR
(KBr) νmax cmÀ1: 3240, 3174 (NH), 1658 (C═O);
1H-NMR (DMSO-d6) (δ, ppm): 2.13 (s, 3H, CH3), 5.45 (s,
1H, pyrim H-4), 5.97 (s, 2H, O─CH2O─), 6.70–7.44 (m,
6H, Ar─H), 7.93 (s, 1H, thiazole H-4), 9.51, 10.13, 11.90
(3s, 3H, 3NH); Anal. Calcd for C22H17ClN6O3S2
(MW: 512.9): C, 51.51; H, 3.34; N, 16.38%. Found: C,
51.44; H, 3.12; N, 16.24%.
N, 9.99%.
5-Benzo[1,3]dioxol-5-yl-7-methyl-3-oxo-2,3-dihydro-5H-
thiazolo[3,2-a]pyrimidine-6-carboxylic
acid
phenylamide
(5b).
Yellow crystals (xylene); yield 68%, mp 140–
143°C; IR (KBr) νmax cmÀ1: 3373 (NH), 1730, 1649
(C═O); MS: m/z 407 (M+, 12.09%); H-NMR (DMSO-
1
d6) (δ, ppm): 2.05 (s, 3H, CH3), 4.05–4.15 (dd, 2H,
CH2, J = 18 Hz), 5.30 (s, 1H, pyrim H-4), 5.97 (s, 2H,
O─CH2O─), 6.71–7.54 (m, 8H, Ar─H), 9.70 (s, 1H,
NH); Anal. Calcd for C21H17N3O4S (MW: 407.44): C,
61.90; H, 4.21; N, 10.31%. Found: C, 61.68; H, 4.11;
N, 10.12%.
5-Benzo[1,3]dioxol-5-yl-7-methyl-3-oxo-2,3-dihydro-5H-
thiazolo[3,2-a]pyrimidine-6-carboxylic
acid
(4-methoxy-
phenyl)-amide (5c).
Pale yellow crystals (EtOH); yield
76%; mp 198–200°C; IR (KBr) νmax cmÀ1: 3290 (NH),
1
1736, 1640 (C═O); H-NMR (DMSO-d6) (δ, ppm): 2.05
Dyeing of polyester fabrics procedure using conventional
(s, 3H, CH3), 3.68 (s, 3H, OCH3), 4.05–4.15 (dd, 2H,
CH2, J = 17.5 Hz), 5.92 (s, 1H, pyrim H-4), 6.71–7.44
(m, 7H, Ar─H), 9.77 (s, 1H, NH); Anal. Calcd for
C22H19N3O5S (MW: 437.47): C, 60.40; H, 4.38; N,
9.61%. Found: C, 60.21; H, 4.29; N, 9.42%.
method.
Polyester fabric samples (0.3 g) were dyed
with the disperse dyestuff (6a,b–7) at liquor ratio 1:20.
Dyeing was carried out at different concentrations of dye
(2%, 4%, and 6%, respectively). The dye was dissolved
in ethanol and added dropwise with stirring to a solution
of an anionic dispersing agent (0.012 g/dm3), and then,
the dye precipitated in a fine dispersion was ready for use
in dyeing. The dyebath, containing 0.03 g/dm3 carrier,
4% acetic acid at pH = 5.5, brought to 60°C. The
polyester fabric was entered and run for 15 min, and
then, the fine dispersion of the dye was added, and the
temperature raised to boiling within 45 min. Dyeing was
continued at boiling temperature (120°C) for about 1 h,
and then the dyed material was rinsed and soaped with
2% nonionic detergent [48].
General procedure for synthesis of arylazothiazolo[3,2-a]
pyrimidines 6a,b.
A
solution of thiazolo[3,2-a]
pyrimidines 5a–c (0.01 mol) in ethanol/water mixture
(1:1) containing sodium acetate anhydrous (2 g) was
treated with (0.01 mol) aromatic diazonium chloride at 0–
5°C with continuous stirring. The reaction mixture was
left overnight in the refrigerator. The precipitates formed
were collected by filtration and recrystallized from
suitable solvents to give crystals of 6a–b.
5-Benzo[1,3]dioxol-5-yl-2-(2-chloro-phenylazo)-7-methyl-3-
oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic
Color fastness tests.
Fastness properties to washing,
acid phenylamide (6a).
Yellow crystals (EtOH/H2O);
yield 81%; mp 173–177°C; IR (KBr) νmax cmÀ1: 3467
(NH), 1712, 1651 (C═O); MS: m/z 545 (M+, 14.17%);
1H-NMR (DMSO-d6) (δ, ppm): 2.12 (s, 3H, CH3), 5.96
(s, 1H, pyrim H-4), 5.99 (s, 2H, O─CH2O─), 6.72–7.72
(m, 7 H, Ar─H), 9.97, 12.25 (2s, 2H, 2NH); Anal. Calcd
for C27H20ClN5O4S (MW: 545.5): C, 59.39; H, 3.69; N,
12.83%. Found: C, 59.28; H, 3.51; N, 12.74%.
rubbing, and light of the dyed polyester fabrics were
determined according to JIS L 0844, JIS L 0849, and JIS
L 0842:2004 test methods, respectively.
Fastness to washing.
A specimen of dyed polyester
fabric was stitched between two pieces of undyed cotton
fabric (all fabric pieces had the same diameter) and then
washed at 50°C for 30 min. The staining of the undyed
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

T. Abou Elmaaty, F. El-Taweel, S. Abdeldayem, and A. Abou Elfarh
Vol 000
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adjacent fabric was assessed using gray scale (1, poor;
2, fair; 3, moderate; 4; good; 5, excellent).
Fastness to rubbing.
The dyed polyester fabric was
placed on the base of a Crockmeter so that it was rested
flat on the abrasive cloth with its long dimension in the
direction of rubbing. A square of white testing cloth was
forced to slide on the tested fabric back and forth 20
times by turning the crank 10 complete turns. For the wet
rubbing test, the test square was thoroughly wetted in
distilled water. The rest of the procedure was the same as
the dry test. The staining on the white testing cloth was
assessed using gray scale (1, poor; 2, fair; 3, moderate; 4;
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Light fastness was determined by
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moderately faded; 5, no change) (Table 1).
Color assessment. The color parameters of the dyed
polyester fabric were measured using the (Konica
Minolta CM-3600 d) spectrophotometer. The following
CIELAB coordinates were measured: lightness (L*),
chroma (C*), hue (h), the degree of redness (+ve) and
greenness (Àve) (a*), and the degree of yellowness (+ve)
and blueness (Àve) (b*). The color strength (K/S) values
were obtained using the (Konica Minolta CM-3600 d)
spectrophotometer (Table 2). The Raman spectra were
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet