izonsteride izonsteride izonsteride (developmental code name ly-320,236) is a selective inhibitor of the 5α-reductase, with dual effects on both the type i and type ii isoforms of the enzyme. it was under development by eli lilly and company and fujisawa for the treatment of benign prostatic hyperplasia but was never marketed. izonsteride may also be useful in the treatment of androgenic alopecia. izonsterideclinical dataother namesly-320,236routes ofadministrationby mouthatc codenoneidentifiers iupac name (4ar,10br)-8--4,10b-dimethyl-1,4,4a,5,6,10b-hexahydrobenzoquinolin-3(2h)-one cas number176975-26-1pubchem cid172988chemspider151061uniia5e8c36f34comptox dashboard (epa)dtxsid80170230 chemical and physical dataformulac24h26n2os2molar mass422.61 g·mol−13d model (jsmol)interactive image smiles o=c4n(c)5ccc3cc(sc1nc2c(cccc2s1)cc)ccc35(c)cc4 chemistry synthesis the scheme used to produce a somewhat more complex 5-a-reductase inhibitor relies on a chiral auxiliary to yield the final product as a single enantiomer. the first step starts with the reaction of bromotetralone with r-α-phenethylamine to afford the enamine. reaction with methyl iodide adds the methyl group at what will be a steroid-like ab ring junction. preparation of izonsteride this product is then treated with acryloyl chloride. the initial step in this case probably involves the acylation of nitrogen on the enamine; conjugate addition then completes the formation of the lactam ring. treatment of that product with triethyl silane then reduces the ring unsaturation and cleaves the benzylic nitrogen bond on the auxiliary to yield as the optically pure trans isomer. displacement of bromine with the mercapto benzthiazole completes the synthesis of izonsteride.