Catalyst-free photoarylation of 2-aryl-2H-indazoles by carbon-iodine bond activation

A photocatalyst-free visible-light induced arylation of 2-aryl-2H-indazoles with aryl iodides has been developed for the first time to produce 3,2-diaryl-2H-indazoles in good to moderate yields. In this transformation, potassium tert-butoxide acts as an activator of the C-I bond and also as a scavenger of in situ generated HI in the reaction. This method exhibits high functional group tolerance with a wide substrate scope and it has been successfully applied to the synthesis of liver X receptor agonists and also for fluorescent probes. This is the first report on the photoarylation of 2-arylindazoles at the C3-position with aryl iodides under catalyst-free conditions.

Photophysical evaluation on the electronic properties of synthesized biologically significant pyrido fused imidazo[4,5-c]quinolines

A single pot microwave assisted method was employed to synthesize a series of novel pyrido fused imidazo[4,5-c]quinolines. The electronic properties of these derivatives were investigated by following their photophysical behaviour under isolated and solvated conditions via computational and experimental approaches. The solvatochromic effect of these derivatives was investigated in the ground and excited singlet states by following the absorption and fluorescence emission and excitation spectra. Further the effect of general and specific solvent effects were also investigated by plotting Stokes shift against Lippert-Mataga, ET(30) and Kamlet-Taft polarity parameters respectively. The deviation from linearity in ET(30) plot indicates that formation of different species in polar protic solvents. The biological applications of these derivatives as potential drug candidates were evaluated by in silico computational methods followed by pharmacokinetic properties predictions. The ability of these derivatives to inhibit human casein kinase 2 (CK2) was evaluated. The structure activity relationships were correlated by evaluating the electronic properties through experimental photophysical investigations including solvatochromic effect and computational electronic structure calculations. Of the various derivatives, p-nitro phenyl substituted pyrido fused imidazo[4,5-c]quinoline exhibited good inhibitory activity against CK2 enzyme and hence could serve as a promising drug candidate.

A comprehensive survey upon diverse and prolific applications of chitosan-based catalytic systems in one-pot multi-component synthesis of heterocyclic rings

Heterocyclic compounds are among the most prestigious and valuable chemical molecules with diverse and magnificent applications in various sciences. Due to the remarkable and numerous properties of the heterocyclic frameworks, the development of efficient and convenient synthetic methods for the preparation of such outstanding compounds is of great importance. Undoubtedly, catalysis has a conspicuous role in modern chemical synthesis and green chemistry. Therefore, when designing a chemical reaction, choosing and or preparing powerful and environmentally benign simple catalysts or complicated catalytic systems for an acceleration of the chemical reaction is a pivotal part of work for synthetic chemists. Chitosan, as a biocompatible and biodegradable pseudo-natural polysaccharide is one of the excellent choices for the preparation of suitable catalytic systems due to its unique properties. In this review paper, every effort has been made to cover all research articles in the field of one-pot synthesis of heterocyclic frameworks in the presence of chitosan-based catalytic systems, which were published roughly by the first quarter of 2020. It is hoped that this review paper can be a little help to synthetic scientists, methodologists, and catalyst designers, both on the laboratory and industrial scales.