Synthesis of 5α-Reductase Special Inhibitor Finasteride

The document described the synthesis process of Finasteride, a 5α-reductase inhibitor. The synthesis involved multiple chemical reactions starting with the intermediate N-tert-butyl-3-oxo-4-aza-5-androst-17β-Formamide, which was derived from 3β-Hydroxypregn-5-en-20-one. The process included bromoform reaction, esterification, oxidation, reduction, and amination reactions. Finasteride was then prepared through dehydrogenation at the 1,2-position, followed by iodination and iodine removal.