Regioselective activation of benzocyclobutenones and dienamides lead to anti-Bredt bridged-ring systems by a [4+4] cycloaddition.

It was found that changing the electronegativity of aryl substituents on δ-position of dienamides ( 1a–1d ) does not affect the efficacy, and 68–75% yields were obtained, with a slight trend for para -substituted effect favoring electron-withdrawing groups (entry 1–4, Fig. 3 ).

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