IMPROVED SYNTHESES OF EPRISTERIDE, A POTENT HUMAN 5-ALPHA-REDUCTASE INHIBITOR

Two improved syntheses of a potent human 5 alpha-reductase inhibitor, epristeride, SK&F 105657, are described. The first synthesis starts fr om methyl 3-oxoandrost-4-ene-17 beta-carboxylate (1), which is convert ed to epristeride (5) in four synthetic steps in 44% overall yield. Th e second synthesis starts from commercially available 3-oxoandrost-4-e n-17 beta-carboxylic acid (7), which is converted to epristeride (5) i n two synthetic steps in 63% overall yield. Both syntheses are suitabl e for large scale production and have been employed to produce kilogra ms supplies of epristeride in high purity.