Cholest-5-ene- and Stigmasta-5,22-diene-Based 1,3-Oxathiolan-5-one Lactones and an Aminothiazole-Diosgenin Hybrid: Synthesis and Preliminary Antimicrobial Activity.

Novel steroidal heterocyclic derivatives were prepared from cholesterol, stigmasterol, and diosgenin scaffolds via concise, reagent-efficient synthetic routes. Two 1,3-oxathiolan-5-one derivatives bearing cholest-5-ene (7) and stigmasta-5,22-diene (8) cores were obtained from the corresponding steroidal ketones through hydrazone formation, phenyl isothiocyanate addition, and S-selective cyclization with chloroacetic acid in refluxing toluene. An aminothiazole-diosgenin hybrid (12) was independently prepared via regioselective α-bromination of an oxidized diosgenin intermediate followed by condensation with thiourea in ethanolic sodium ethoxide. The newly synthesized target compounds were characterized by FT-IR, 1H- and 13C-NMR spectroscopy, ESI mass spectrometry, and elemental (CHNS) analysis. The disc-diffusion assay against S. aureus and E. coli was retained only as a preliminary qualitative screen because no positive antibiotic control or MIC determination was included. Within this limited screen, compound 12 produced measurable 8.5-9.0 mm inhibition zones against both strains, supporting their prioritization for future standardized antimicrobial testing rather than establishing comparative potency.