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.