A short and efficient synthesis of novel benzo [c] quinolizin-3-one derivatives is described. The synthesis is based on the tandem Mannich-Michael cyclization between 2-silyloxy-1, 3- butadienes and a Nt-Boc iminium ion. The prepared derivatives are selective inhibitors of human steroid 5α-reductase isoenzyme 1, thus having potential application as drugs for treatment of male pattern baldness and other DHT-dependent skin disorders.