A ligand-free copper-catalyzed tandem azide-alkyne cycloaddition (CuAAC), Ullmann-type C-N coupling, and intramolecular direct arylation has been described. The designed strategy resulted in the synthesis of a novel trazole-fused azaheterocycle framework. The reaction gave good yields (59-77%) of 1,2,3-triazole-fused imidazo[1,2-a]pyridines in a single step.
N N cyclocondensations oxidative cyclizations multicomponent reactions rearrangements tandem processes
C-H activations/functionalizationsAbstract Advances in the last decade for the synthesis of the imidazo[1,2-a]pyridine scaffold from various substrates employing approaches such as multicomponent reactions, tandem processes, rearrangement reactions, inter-and intramolecular oxidative/reductive cyclizations, and transition-metal-catalyzed C-H activation are summarized in this review. The mechanisms for the selected transformations are also discussed. 1
An efficient one-pot sequential procedure is described for the synthesis of novel azole-fused quinazolines through Pd/Cu co-catalyzed, Ullmann-type coupling followed by cross dehydrogenative coupling of various azoles such as 1H-imidazole, 1H-benzimidazole and 1H-1,2,4-triazole with 2-(2-bromophenyl)-1H-imidazole/benzimidazoles. The developed strategy has offered good yields (52-81%) of diverse N-fused tetra-, penta- and hexa-cyclic frameworks in a single step.
An efficient one-pot protocol has been developed using sequential C-N coupling and intramolecular dehydrogenative cross-couplings for the synthesis of azole fused imidazo[1,2-a]pyridine derivatives in good yields (62-78%).
An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared.The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck crosscoupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology.H and 13 C NMR, and mass spectrometry data for the ionic liquid-supported Schiff base (4) and its Pd complex (5), and 1 H and 13 C NMR data for 8 & 10. See
A new strategy is reported for the synthesis of 6-aminoquinoline derivatives via a tandem Povarov reaction, dihydroquinoline oxidation, and imine reduction. These products allow access to symmetrical as well as unsymmetrical tetraarylpyrido[2,3-g]quinolines, potentially useful organic electronics.
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