Synthesis of Pyrazoloazepines from 5‐Aminopyrazoles and Study of Their Cytotoxicity in Cancer Treatment

The novel synthetic approach was employed to synthesize a series of 1,8‐dihydropyrazolo[3,4‐b]azepine derivatives from 5‐aminopyrazoles in three‐step synthesis. The structures of the individual derivatives were unambiguously confirmed by spectral methods, including heteronuclear 1H−13C HMBC spectra and other necessary 2D NMR experiments. The obtained pyrazoloazepines and starting aminopyrazoles were subsequently investigated for their potential cytotoxic effect using mouse and human leukemia cell models. The original L1210 (mouse lymphoblastic), MOLM‐13, and SKM‐1 (both human myeloblastic) cell lines and their P‐glycoprotein (P‐gp) expressing cell variants were used. Aminopyrazole 8 was the most effective on murine leukemic lymphoblasts (L1210), while it had a greater effect on P‐gp expressing cells. In contrast, on human leukemic myeloblasts (MOLM‐13, SKM‐1), Aminopyrazoles 10 showed the most pronounced effect, but this was independent of the presence of P‐gp in the cells. This research expands upon the synthesis of 1,6‐dihydropyrazolo[3,4‐b]azepines by optimization of reaction conditions for N‐substituted 1,8‐dihydropyrazolo[3,4‐b]azepine derivatives. Structures are confirmed by 2D NMR analysis. The obtained derivatives are tested for their potential cytotoxic effect using mouse and human leukem