17-alpha-Ethynyl-11-beta-methylestradiol-3-cyclopentyl ether 17alpha-Ethynyl-11beta-methyl estradiol-3-cyclopentyl ether 19-Norpregna-1,3,5(10)-trien-20-yn-17-ol, 3-(cyclopentyloxy)-11-methyl-, (11-beta,17-alpha)- 55648-36-7 SC-20775