Abstract cis-and trans-(3, 6-D 2)-1, 4-cyclohexadienes 1a and 1b have been synthesized from cis-3, 4-dichlorocyclobutene (5). Aromatization to benzene with DDQ is cis- stereospecific with an uncertainty of 5%. This result is discussed in relation to concerted or stepwise mechanisms for aromatization of 1, 4-dihydroaromatics with 2, 3-dichloro-5, 6- dicyano-p-benzoquinone (DDQ).
