2-(Bis(methylthio)methylene)-3,5,5-trimethylcyclohex-3-enone is an intermediate for the synthesis of 1,1,5,5-Tetramethyl-2-(1-methylethenyl)cyclohexane (T305630), which is analyzed in synthetic elastomers and natural rubber studies of cyclic oligomer formation in the copolymerization of isoprene with isobutylene.