A series of 2-arylbenzo[d]imidazo[2,1-b] thiazoles tethered with barbituric acid has been prepared using I2 in DMSO medium under conventional or microwave heating conditions.
Herein, we report
a metal-free one-pot three-component reaction
of aryl methyl ketones, 2-aminopyridines, and barbituric acids for
the synthesis of pyrimidine-linked imidazopyridines using a catalytic
amount of molecular iodine in DMSO medium. This process involves a
one-pot C–H oxidation, followed by the formation of one C–C
and two C–N bonds. A wide variety of aryl methyl ketones and
2-aminopyridines were found to be suitable for this methodology. The
UV and fluorescence properties of the synthesized products were studied
in water and DMSO media. Most of the synthesized products exhibited
very good to excellent fluorescence quantum yield. Among all the products,
compounds
4p
and
4q
showed the maximum fluorescence
quantum yield (0.36) in water medium under basic conditions and compound
4c
showed the maximum fluorescence quantum yield (0.75) in
DMSO medium.
A series of novel diphenyl-1,3-thiazole linked barbituric acid hybrids (4) were prepared by two catalyst-free methods from readily available starting materials.
Herein, we report a simple and efficient
method for the preparation
of novel thioether-linked coumarin-fused furans from the one-pot three-component
reaction of arylglyoxal, 4-hydroxycoumarin, and various aromatic thiols
in the presence of Sc(OTf)3 as a catalyst. This methodology
is also applicable to cyclic 1,3-dicarbonyls such as cyclohexane-1,3-dione
and dimedone. Depending upon the thiols, this methodology can either
give a three-component thioether-linked coumarin-fused furan (4) or a two-component furocoumarin product (5). Wide substrate scope, good to excellent yields, and products having
more than one pharmaceutically important motif are the salient features
of this methodology.
Herein, we report an efficient multicomponent reaction
for the
synthesis of trisubstituted thiazoles involving a one-pot C–C,
C–N, and C–S bond-forming process from the readily available
starting materials. The reaction of arylglyoxal, indole, and aryl
thioamides in the acetic acid medium under sealed heating conditions
provided 3-(2,4-diarylthiazol-5-yl)-1H-indoles (4) in good to excellent yields. Using a similar reaction strategy,
the reaction of arylglyoxal, aryl thioamide, and 2,5-dihydroxy-1,4-benzoquinone
provided structurally interesting bis-thiazoles having dihydroxy-1,4-benzoquinone
linker (9). All of the products were fully characterized
by spectroscopic techniques. We also recorded single-crystal X-ray
diffraction (XRD) of compounds 4b and 9a for unambiguous structure determination. Indole-linked trisubstituted
thiazoles (4) exhibit prominent fluorescence properties.
The relative fluorescence quantum yields of all of the thiazole-linked
indoles were measured in the dimethyl sulfoxide (DMSO) medium with
respect to quinine sulfate in 0.1 M H2SO4 as
reference. The scope of this reaction was further explored by preparing
novel polymers 11a and 11b using naphthalene/benzene-1,4-bis(carbothioamide)
in multicomponent polymerization.
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