Photochemical rearrangement of 2,3-dihydroisoxazoles. Formation of stable azomethine ylides via acyl aziridines as intermediates

Irradiation of the 2,3-annulated 2,3-dihydroisoxazoles 3 affords azomethine ylides 4 as isolate compounds, which on heating are transformed into the tetrahydroindolizines 7 and 8.