Synthesis and cytotoxic activity against human tumor cells of heterocyclic systems derived from 2‐thioxo‐1,2‐dihydro‐4H‐3,1‐benzothazin‐4‐one

The title compound was prepared and converted to 2‐hydrazinyl‐1,2‐dihydro‐4H‐benzo[d][1,3]thiazin‐4‐one which was utilized to synthesize fused heterocyclic systems, namely benzotriazolothiazinone derivatives, as well as, nonfused heterocyclic systems such as pyrazolyl‐benzothiazinones, benzothiazinylpyridazine and imidazolylbenzothiazinone derivatives via reaction with formamide, acetic acid, ethyl cyanoacetate, maleic anhydride and benzaldehyde followed by treatment with glycine, respectively. All compounds have been structurally characterized by means of IR, MS, and 1H‐NMR spectra. The synthesized compounds were evaluated in vitro for their antiproliferative activity against HePG‐2 and MCF‐7 cell lines. 2H‐Benzo[d][1,3]thiazine‐2,4(1H)‐dithione and 2‐thioxo‐1,2‐dihydro‐4H‐benzo[d][1,3]thiazin‐4‐one were the most potent against the two cancer cells compared to that of the reference compound doxorubicin. Most of the synthesized compounds also exhibited good cytotoxic activity.