1,2a,3,6,7,8-Hexahydro-cyclopenta[cd]pyren-4(2H)-one is an intermediate used in the synthesis of Acepyrene (A130950), which is a novel constituent discovered that belongs to the pyrene class of the polycyclic aromatic hydrocarbons. Acepyrene occurs in a large variety of carbon black soots, in cigarette smoke and is the major representative of PAH in car engine exhaust gases.