Selenium heterocycles XXIII. Synthesis of 4,5-dihydrophenanthro[1,3-d]-1,2,3-selenadiazoles and 10,11 -dihydrophenanthro[1,2-d]-1,2,3-selenadiazoles

The selenium dioxide oxidation of a series of 1,2,3,4-tetrahydrophenanthrone and 1,2,3,4-tetrahydrophenanthren-4-one semicarbazones afforded 4,5-dihydrophenanthro4,3-d]-1,2,3-selenadiazoles and 10,11-dihydrophenanthro1,2-d]-1,2,3-selenadiazoles. The latter series which represent a new type of selenaazasteroidal compounds were pyrolyzed and gave the corresponding 1,4-deselenine derivatives.