Synthesis of bioactive polyheterocyclic ring systems as 5α-reductase inhibitors.

Simple synthetic strategies for the hitherto unreported [1,2,4]triazolo[4,3-a]pyrido[4,3-d]pyrimidines 8 and [1,2,4]triazolo[4',3':1,2]pyrimido[4,5-b][1,6]naphthyridine-5-one 15 are described based on reaction of thione 3 and 12 with hydrazonoyl chloride 1a-h, respectively. The structures of products 8 and 15 were confirmed by spectroscopic and X-ray crystallographic analyses. Also, the mechanism of such reactions was discussed. In addition, reaction of compound 12 with bromoacetic acid and hydrazine hydrate was investigated. Compounds were screened against 5α-reductase and showed activities with good LD(50) and LD(90) for all compounds.