Tandem synthesis of 4-aminoxanthones is controlled by a water-assisted tautomerization: a general straightforward reaction
作者:Ana Bornadiego、Jesús Díaz、Carlos F. Marcos
DOI:10.1039/c8ob02527d
日期:——
synthetically challenging. Here, we report the synthesis of both aminodihydroxanthones and fully aromatized aminoxanthones by an easy to perform, one-step multicomponent reaction of isocyanides, 3-carbonylchromones and dienophiles. The mechanism of the reaction involves a sequence of a [4 + 1] cycloaddition, iminolactone-aminofuran tautomerization, [4 + 2] cycloaddition, oxygen ring opening and aromatization
3-Methoxalylchromone—a novel versatile reagent for the regioselective purine isostere synthesis
作者:Satenik Mkrtchyan、Viktor O. Iaroshenko、Sergii Dudkin、Ashot Gevorgyan、Marcelo Vilches-Herrera、Gagik Ghazaryan、Dmitriy M. Volochnyuk、Dmytro Ostrovskyi、Zeeshan Ahmed、Alexander Villinger、Vyacheslav Ya. Sosnovskikh、Peter Langer
DOI:10.1039/c0ob00379d
日期:——
The first synthesis of 3-methoxalylchromone was described. The reaction of the latter with electron-rich aminoheterocycles afforded a set of heteroannelated pyridines bearing a CO2Me substituent located at the α-position of the pyridine core.
Reactions of 3-acylchromones with dimethyl 1,3-acetonedicarboxylate and 1,3-diphenylacetone: one-pot synthesis of functionalized 2-hydroxybenzophenones, 6H-benzo[c]chromenes and benzo[c]coumarins
作者:Viktor O. Iaroshenko、Iryna Savych、Alexander Villinger、Vyacheslav Ya. Sosnovskikh、Peter Langer
DOI:10.1039/c2ob07020k
日期:——
Reactions of 3-methoxalyl-, 3-polyfluoroacyl- and 3-aroylchromones with dimethyl 1,3-acetonedicarboxylate and 1,3-diphenylacetone in the presence of DBU proceed at the C-2 atom of the chromone system with pyrone ring-opening and subsequent formal [3 + 3] cyclocondensation to functionalized 2-hydroxybenzophenones, 6H-benzo[c]chromenes and benzo[c]coumarins, depending on the substituent at the 3-position. An NMR study and X-ray crystallographic analysis are reported. The compounds synthesized can be considered as promising scaffolds for the design of the novel UV-A/B and UV-B filters.
The reaction of 5-amino-1H-imidazoles with 3-methoxalylchromone provided a set of imidazo[4,5-b]pyridines (1-desazapurines) bearing the CO2Me substituent at the α-position of the pyridine core. The corresponding acids were synthesized by subsequent hydrolysis of the ester function. Being typical purine isosteres, 1-desazapurines are considered to be potent pharmacophores, and are widely used in drug design and medicinal chemistry.
Regioselective Tandem [4 + 1]–[4 + 2] Synthesis of Amino-Substituted Dihydroxanthones and Xanthones
作者:Ana Bornadiego、Jesús Díaz、Carlos F. Marcos
DOI:10.1021/acs.joc.5b00658
日期:2015.6.19
A highly convergent and operationally simple approach to mycotoxin-related 4-amino-substituted 1-hydroxy-dihydroxanthones is described. The target compounds are obtained in one pot by the multicomponent reaction of 3-carbonylchromones, isocyanides, and nonsymmetric dienophiles. The reaction, which involves a tandem [4 + 1]-[4 + 2] cydoaddition, efficiently affords a variety of both monomeric and dimeric polysubstituted dihydroxanthones structurally similar to bioactive ergochromes. Further aromatization to the corresponding xanthones is readily achieved by treatment with DBU under microwave irradiation.