Photochemical generation of the 2-azabicyclo[4.2.0]octa-4,7-diene skeleton.

A 2-azabicyclo[4.2.0]octa-4,7-diene derivative was unexpectedly isolated from the photochemical irradiation of 2-vinyl-1,2-dihydropyridine. A cascading 6π–8π–4π electrocyclic rearrangement has been proposed as a possible mechanistic pathway. Herein disclosed is the isolation of the 2-azabicyclo[4.2.0]octa-4,7-diene skeleton derived from the photochemical irradiation of 2-vinyl-1,2-dihydropyridine. A cascading 6π–8π–4π electrocyclic rearrangement is proposed as the mechanistic rationale. This is the first observation of this ring system. [ABSTRACT FROM AUTHOR]