One-pot domino synthesis of 1,2,4-triazolo [3,4-b][1,3,4] 6-amino thiadiazines and their CT-DNA binding study

A facile one-pot three component domino protocol has been successfully developed for the combinatorial synthesis of novel Schiff bases of 3-(2-(6-amino-7H- [1,2,4]-triazolo[3,4-b] [1,3,4]thiadiazin-3-yl)hydrazineylidene) indolin-2-ones 4, 5. This protocol utilizes readily available starting materials, leads to produce high yields (79-92 %).This domino reaction involves the formation of three new bonds (two C--N and one C-S bond) and one heterocyclic ring in a single step. Notably, this reaction shows several remarkable features, such as short reaction time, eliminating the requirement for extensive workup and column chromatographic purification. In addition to this, the reaction demonstrates good scalability, producing satisfactory yields even on a gram -scale. Further, all the compounds were screened for their electronic absorption and fluorescence emission spectral studies by using CT-DNA. Compounds 5l, 5m, 5r, 5o, 5s have shown greater binding affinity with CT-DNA. In fluorescence emission spectra 5l, 5o, 5s demonstrate good quenching constant values with CT-DNA. And also, molecular docking studies were carried out for all the synthesized compounds.