Sn(II)-Mediated facile approach for the synthesis of 2-aryl-2: H -indazole-3-phosphonates and their anticancer activities

A convenient three-component method was developed for the synthesis of various 2-aryl-2H-indazole-3-phosphonates using SnCl₂·2H₂O under conventional heating techniques. The transition metal free reaction, mild reaction conditions, one-pot operation, open flask conditions, wide substrate scope and good yields are a few important features of this methodology. This protocol proceeds with high atom economy via the formation of α-aminophosphonates followed by the generation of an indazole ring through N-N bond formation, eliminating water as a by-product. The cytotoxic properties of the 2-aryl-2H-indazole-3-phosphonate derivatives were investigated against A549 and HepG-2 cells. Interestingly, compounds 4d and 4g showed potent cytotoxic properties against HepG-2 cells and compound 4p showed significant cytotoxic properties against A549 cells. Intracellular visualization was done using a laser scanning confocal microscope. DNA fragmentation, colony formation, and apoptosis studies, flow cytometry and western blot analysis for 4p against A549 cells have also been reported.