1-(2,4,4,5,5-Pentamethyl-1-cyclopenten-1-yl)ethan-1-one 13144-88-2 2-Acetyl-1,3,3,4,4-pentamethylcyclopentene EINECS 236-080-0 Ethanone, 1-(2,4,4,5,5-pentamethyl-1-cyclopenten-1-yl)-