Beilstein J. Org. Chem.2025,21, 358–368, doi:10.3762/bjoc.21.26
leads to new 2-(benzo[e(g)]indolin-2-yl)-5,6,7-trichloro-1,3-tropolones and 2-(benzo[e(g)]indolin-2-yl)-4,5,6,7-tetrachloro-1,3-tropolones. Based on the results of PBE0/6-311+G(d,p) calculations, the structural and energetic characteristics of the tautomeric forms of the obtained 1,3-tropolones were
-(1,1-Dimethyl-1H-benzo[e]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone exhibited high in vitro cytotoxic activity against A431 skin cancer and H1299 lung cancer cell lines.
Keywords: cytotoxic activity; fluorescence; o-chloranil; quantum chemical DFT calculations; 1,3-tropolones; X-ray diffraction
-methylquinazolinones [3], 2-methylbenzoxazinones [4], and 2-methylbenzoxa(thia)zoles [5] the interaction with sterically hindered 1,2-benzoquinones and 3,4,5,6-tetrachloro-1,2-benzoquinone proceeds with the expansion of the o-quinone ring and results in 2-hetaryl-substituted 1,3-tropolones 1 (Scheme 1), which exhibit
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Graphical Abstract
Scheme 1:
Synthesis of 2-hetaryl-substituted 1,3-tropolones 1.
Beilstein J. Org. Chem.2015,11, 2179–2188, doi:10.3762/bjoc.11.236
the three representative compounds were determined by X-ray crystallography. In crystal and (as shown by the DFT PBE0/6-311+G** calculations) in solution, 2-hetaryl-4,5,6,7-tetrachloro- and 2-hetaryl-5,6,7-trichloro-1,3-tropolones exist in the NH-tautomeric form with a strong resonance-assisted
intramolecular N–H···O hydrogen bond. The mechanism of the formation of 1,3-tropolones in the reaction of methylene-active five-membered heterocycles with o-chloranil in acetic acid solution has been studied using density functional theory (DFT) methods. The reaction of 2-(2-benzoxa(thia)zolyl)-5,6,7-trichloro
(4,5,6,7-tetrachloro)-1,3-tropolones with alcohols leads to the contraction of the seven-membered tropone ring with the formation of 2-(2-benzoxa(thia)zolyl)-6-alkoxycarbonylphenols. The molecular structure of 2-(2-ethoxycarbonyl-6-hydroxy-3,4,5-trichlorophenyl)benzoxazole has been determined by X-ray
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Graphical Abstract
Scheme 1:
1,3-Tropolones 2–4 prepared by the reaction of o-chloranil with methylene active compounds.