A Catalyst-Controlled Divergent Rearomatization of BN-Benzvalene

Carbon-based benzvalene undergoes diverse rearrangements upon exposure to external stimuli. In this report, we investigate the thermal and metal-catalyzed rearomatization pathways of BN-benzvalene, a boron-nitrogen-containing valence isomer of benzene. Depending on the choice of metal catalyst, these transformations selectively yield either C5- or C3-functionalized 1,2-azaborines. The C5-isomer formation serves as a proof of concept for a new molecular photoswitch system, while the C3-isomer formation represents the functional group transposition on the 1,2-azaborine scaffold. Mechanistic investigations, such as deuterium labeling studies and DFT calculations, suggest distinct operative pathways for the generation of each isomer.