Synthesis of some 5α-Androstano[17,16-d]pyrazoles from Tigogenin

Condensation reaction of several arylhydrazines with 16α, 17α-epoxy-5α-pregnan-3βol-20-one synthesized from 5α-pregn-16-en-3β-ol-20-one–intermediate product of tigogenin transformation – were studied for the purpose of synthesizing potentially bioactive 5-androstano [17,16-d] pyrazoles. Despite various conditions (different temperature, in protic and aprotic solvents) of the reaction, a complex mixture was obtained and then separated by column chromatography (eluent-hexane-ethylacetate). Two main products of intermolecular cyclization: 5α-androstano [17,16-d] pyrazole and its hydrogenated analogue – 5α-androstano [17,16-d]pyrazolines were isolated by substitution of electron-donating group (phenylhydrazine, p-methyl-, p-bromophenylhydrazine) at the hydrazine amine atom. In the presence of electron-withdrawing group (p-nitrophenylhydrazine) at the hydrazine amine atom cis-opening product of epoxygroup – 16αacetoxy-5α-pregnan-3β, 17α-diol-20-one hydrazine – was obtained. The structures of synthesized compounds were established by NMR 1H, 13C and mass-spectral data. Structures of 3β-hydroxy-1/phenyl-3/-methyl-5α-androstano [17,16-d] pyrazoles were confirmed by IR, NMR 1H, 13C, DEPT-135, HMBC and mass-spectral data. Synthesis of 5α-androstano [17,16-d] pyrazolines with 5α-androstano [17,16-d] pyrazoles by condensation reactions in the mentioned conditions was not described previously. © 2018 Bull. Georg. Natl. Acad. Sci.