Generation of Mono- and Bisazabicyclic <i>o</i> -Quinodimethanes through Polarity-Matched and -Mismatched 6π-Azaelectrocyclization: Access to Substituted Naphthalenes

Herein, we demonstrate that 2-alkenylarylaldimines and aryl-1,2-bisaldimines undergo polarity-matched and -mismatched 6π-azacarbo- (6π-AEC) and 6π-aza-azaelectrocyclization (6π-AAEC), respectively, by nitrogen to carbon (azacarbo) and nitrogen to nitrogen (aza-aza) bond formations to generate transient monoazabicyclo- and previously unknown 1,2-bisazabicyclo-<i>o</i>-quinodimethane (<i>o</i>-QDM) intermediates. The monoazabicyclo-<i>o</i>-quinodimethanes engage in a Diels-Alder/retro-Diels-Alder reaction to form substituted dimethyl naphthalene-2,3-dicarboxylates, while the 1,2-bisazabicyclo-<i>o</i>-quinodimethanes react in a Diels-Alder/N-N bond scission reaction to generate 1,4-bis(phenylamino)naphthalene-2,3-dicarboxylates. While polarity-matched 6π-AECs have been explored, polarity-mismatched 6π-AAECs have not been studied due to their complications with the nucleophilic character of iminyl nitrogens at the bond-forming termini.