“…Though many studies on enol ether analogues of progesterone (2)(3)(4)(5)(6)(7) and certain androgens (2,7,(8)(9)(10)(11) have been reported, little is known about similar derivatives of 19-nortestosterone. Experiments with the 3-cyclopentyl enol ether of 17aethynyl-19-nortestosterone-l7p-acetate [ quingestanol acetate (QA)] showed that enol etherification generally enhances most biological activities as compared with its parent ketone (2,4,5,7,12).…”