Structural requirements for progestational activity. Synthesis and properties of...

rac-8alpha,9beta,10alpha,14beta-Progesterone, 1, has been synthesized and subjected to X-ray crystallographic analysis which established that the ring conformations are A, 1beta-sofa; B, chair; C, chair; and D, intermediate between an envelope and a half-chair. This compound is 10% as active as progesterone in the Clauberg assay and has an affinity for the uterine cytosol (rabbit) receptor for progesterone 2% as great as that of progesterone.