pregna-4,20-dien-3,6-dione pregna-4,20-dien-3,6-dione pregnadienedione (pdd), or pregna-4,20-dien-3,6-dione, is a steroid and pherine, or synthetic pheromone. pdd has been found to activate the vomeronasal organ in men. moreover, inhalation by men has been found to affect autonomic and central function and to lower luteinizing hormone and testosterone levels, while inhalation by women has few or no effects. pregna-4,20-dien-3,6-dioneclinical dataother namespregna-4,20-diene-3,6-dioneatc codenoneidentifiers iupac name (8s,9s,10r,13r,14s,17r)-17-ethenyl-10,13-dimethyl-2,7,8,9,11,12,14,15,16,17-decahydro-1h-cyclopentaphenanthrene-3,6-dione pubchem cid15429665chemspider21375166chemical and physical dataformulac21h28o2molar mass312.453 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2c=c)cc(=o)c4=cc(=o)cc34c inchi inchi=1s/c21h28o2/c1-4-13-5-6-16-15-12-19(23)18-11-14(22)7-9-21(18,3)17(15)8-10-20(13,16)2/h4,11,13,15-17h,1,5-10,12h2,2-3h3/t13-,15-,16-,17-,20+,21+/m0/s1key:cnhwgaruxxetpk-smwyyagtsa-n