S-methyl 2,4,4-Trimethyl-6-oxocyclohex-1-enecarbothioate 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.