Controlled Synthesis of Substituted Benzobasketene Derivatives

The addition of benzyne to trans‐7,8‐dibromobicyclo[4.2.0]octa‐2,4‐diene ( 6 ) led to the formation of dibromide 7 . The dehydrobromination of 7 followed by replacement of the Br‐atom with a CN substituent gave 9 . Photolysis of 9 in acetone at 254 nm yielded the desired monosubstituted benzobasketene derivative 10 . Bromination of monobromide 8 followed by dehydrobromination furnished the symmetrically substituted dibromo compound 15 . Further bromination of 7 followed by dehydrobromination resulted in the formation of the dibromides 20 and 21 . Substitution of the Br‐atoms in 15, 20 , and 21 with CN substituents and photolysis of the formed dicarbonitriles 16, 23 , and 24 gave the target benzobasketene‐dicarbonitriles 17, 25 , and 26 , respectively.