Synthesis of fused triazolo[4,5-d]quinoline/chromene/thiochromene derivatives via palladium catalysis mediated by tetrabutylammonium iodide

An expedient approach for the synthesis of various fused triazoles with varying functionality has been developed successfully via palladium catalysis in ligand free conditions. It was found that the additive TBAI greatly facilitates this palladium catalyzed cyclization to achieve the previously inaccessible fused triazolo[4,5-d]quinoline/chromene/thiochromene derivatives. This method provides a fast and simple access to obtain the fused triazoles in good to excellent yields. The synthesized compounds were screened with different cancer cell lines and the results has shown that compound 2a and 2f acts as inhibitors against specific non-small cell lung cancer cell line.