Stereochemistry of Dehydrogenation of 1,4,‐Cyclohexadiene with 2,3‐Dichloro‐5,6‐dicyano‐p‐benzoquinone

Abstract
cis‐ and trans‐(3,6‐D2)‐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).