CuO nanoparticles as a reusable catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives under solvent-free conditions

Dicarbonyl compounds in the synthesis of heterocycles under green conditions

Carbon–carbon and carbon-heteroatom bond forming reactions are strategically employed for the generation of a variety of heterocyclic systems. This class of compounds represents the most general structural unit, present in many natural compounds. They are recognized for their valuable biologically properties and wide range of applications in medicinal, pharmaceutical, and other related fields of chemistry. This is an updated review on the use of dicarbonyl compounds under environmentally friendly conditions to access a series of heterocyclic structures, e.g., quinoxaline, quinazolinones, benzochalcogenazoles, indoles, among others. Synthetic protocols involving copper-catalyzed, multicomponent and cascade reactions, decarboxylative cyclization, recycling of CO2, and electrochemical approaches are presented and discussed.

[TBP]2SO4 ionic liquid catalyst for 4MCR of pyridazinoindazole, indazolophthalazine and pyrazolophthalazine derivatives

Tetrabutyl phosphonium sulfate ([TBP]₂SO₄), as novel room-temperature ionic liquid (RTIL), was synthesized by a simple cost-effective method, characterized by ¹H, ¹³C, ³¹P NMR and FT-IR spectrophotometry. The newly prepared catalyst was used as an efficient catalyst in some four multicomponent reactions (4MCRs) e. g., to synthesis pyridazino[1,2-a]indazole, indazolo[2,1-b]phthalazine and pyrazolo[1,2-b]phthalazine. This green method has several advantages such as short reaction time, using simple methods to prepare catalysts and products, easy operation and high efficiency of products. In addition, the catalyst can be easily recovered and reused several times with reduced average activity.

Experimental and DFT mechanistic insights into one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones under catalysis of DBU-based ionic liquids

Kinetic impacts of two DBU-based ionic liquids in the three-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones and the mechanism of the reaction were investigated by DFT calculations.