1,2,3,4-Tetrakis(3,5-ditert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)cyclobutane

4,4',4'',4'''-(Cyclobutane-1,2,3,4-tetrylidene)tetrakis(2,6-di-tert-butyl-2,5-cyclohexadiene-1-one)

4,4',4'',4'''-(1,2,3,4-Cyclobutanetetrylidene)tetrakis[2,6-bis(1,1-dimethylethyl)-2,5-cyclohexadien-1-one]