[A new class of highly active progestagens: 17 alpha-CH2X-substituted gona-4,9(10)-dienes. 58. Steroids]

The synthesis of new gona-4,9(10)-dienes with a 17 alpha-CH2X-substituent (X = CN, N3, Cl or Br) is described. The progestagenic activity of these substances was studied in the McPhail assay using immature rabbits. The compound XVI (X = CN, STS 557) is the most potent one, showing an activity about ten times higher than D-norgestrel. Differences in the activity caused by different routes of application are discussed.