In the synthesis of diolefins, important compounds that can react with conjugated dienes du are often called dienophiles.
E.g:
CH=CH-CH=CH+CH2=CH2→Cyclohexene
CH=CH-CH=CH+CH2=CH-COOCH3→methyl 4-cyclohexenecarboxylate
Among them, ethylene and methyl acrylate are dienophiles