Photochemistry of halogenocarbon compounds. Part 3. Rearrangements involving azaprismanes

Abstract

Irradiation of perfluoroalkylpyridines containing a high degree of substituent labelling gives in each case a 1-azabicyclo[2.2.0]hexadiene derivative and azaprismanes, which exhibit high thermal stability. Structures of the azaprismanes have been deduced by rearomatisation to pyridines, which are characterised by their ¹⁹F n.m.r. spectra; the spectra reveal conformational preferences for perfluoro-isopropyl and -ethyl groups. To account for the structures of the azaprismanes obtained, rearrangement of an initially produced 2-azabicyclo[2.2.0]hexadiene derivative to the 1-aza-isomer is suggested.