Synthesis of some new testosterone derivatives fused with substituted pyrazoline ring as promising 5alpha-reductase inhibitors.

Condensation of 3beta-hydroxy-16-[(4-chlorophenyl)methylene]androst-5-en-17-one (1) with hydrazine hydrate in acetic acid afforded N-acetyl pyrazoline derivative 2, while condensation of 1 with semicarbazide afforded compound 3. Also, compound 1 was treated with hydrazine hydrate in absolute methanol or ethanol to afford the corresponding alpha-methoxy (4) and alpha-ethoxy (5) derivatives, which were cyclized with etherated boron trifluoride to the pyrazoline derivative 6. The latter could be prepared directly by refluxing 1 with hydrazine hydrate in dioxane.