TFA-catalyzed Q‑Tube Reactor-Assisted Strategy for the Synthesis of Pyrido[1,2‑b][1,2,4]triazine and Pyrido[1′,2′:2,3][1,2,4]triazino[5,6‑b]indole Derivatives

An efficient high-pressure-assisted trifluoroacetic acid-catalyzed protocol for synthesizing unreported novel pyrido­[1,2-b]­[1,2,4]­triazine and pyrido­[1′,2′:2,3]­[1,2,4]­triazino­[5,6-b]­indole derivatives has been established. This strategy includes the condensation reactions of various 1-amino-2-imino-4-arylpyridine-3-carbonitrile derivatives with indoline-2,3-dione (isatin) derivatives and α-keto acids such as pyruvic acid and phenylglyoxylic acid. This strategy includes utilizing the Q-tube reactor as an efficient and safe tool to conduct these reactions under high-pressure conditions. In addition, trifluoroacetic acid was used to induce this transformation. In this research, conducting the targeted reactions under high pressure using the Q-tube reactor was found to be superb in comparison to that under the traditional refluxing conditions. X-ray single-crystal analysis was utilized in this study to authenticate the structure of the synthesized products.