A simple and efficient process is developed for the synthesis of new N‐(1‐alkyl‐3‐chloro‐4‐ethoxy‐1H‐indazol‐5‐yl)‐arylsulfonamides 4a–d and N‐(1‐alkyl‐3‐chloro‐1H‐indazol‐5‐yl)‐arylsulfonamides 5a–d through the reduction of 1‐alkyl‐3‐chloro‐5‐nitroindazoles 2a,b with SnCl2 in ethanol followed by coupling the corresponding amine with arylsulfonyl chlorides in pyridine. All the newly synthesized compounds have been characterized by elemental analysis and spectroscopic data. Some compounds were tested for their in vitro antiproliferative activities against two selected human cancer cell lines A2780 and A549. Among all of these derivatives, compound 5d showed the most potent antiproliferative activity against A2780 (IC50 = 5.47 ± 1.45 μM) and A549 (IC50 = 7.73 ± 1.66 μM) cell lines.

A series of novel indazole–pyrone hybrids are synthesized and tested in vitro against both Leishmania donovani axenic and intramacrophage amastigotes.