PHOTOCHEMISTRY OF CONDENSED ISOXAZOLINES

The condensed bridged isoxazolines 4 are rearranged on irradiation wit h a low-pressure mercury lamp exclusively into condensed derivatives o f tetrahydropyridine 5. The selectivity of the rearrangement is due to a stabilization of the biradical 8 by the overlap of the radical-elec trons with pi-electrons of the C=C double bond and the heterocyclic ri ng. Quantum yields of the photorearrangement, established from the con sumption of the starting materials 4, were determined.