title: Long-acting contraceptive agents: cyclopropyl and cyclobutyl esters of norethisterone.
abstract: Several esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) with carboxylic acids containing a cyclopropyl or cyclobutyl ring have been synthesized and the stereochemistries of the side-chains determined.
mesh_terms: D003692:Delayed-Action Preparations; D004952:Esters; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D009640:Norethindrone / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
chemical_list: D003692:Delayed-Action Preparations; D004952:Esters; D007202:Indicators and Reagents; D009640:Norethindrone