Heterocyclic polyfluoro-compounds. Part 41. Photochemical isomerization of 1-substituted hexafluoro-1H-azepines: hexafluoro-2-azabicyclo[3.2.0]hepta-3,6-dienes and their reactions

Abstract

Photochemical isomerization of 1-ethoxycarbonyl-, 1-cyano-, or 1-amido-hexafluoro-1H-azepine yields the respective 2-substituted hexafluoro-2-azabicyclo[3.2.0]hepta-3,6-diene (92–98%).

The 2-ethoxycarbonylheptadiene undergoes Diels–Alder addition of cyclopentadiene, to give four adducts by exo-attack at the CFCF bonds, and of furan, to give three of the four analogous adducts (attack at the CFCFN bond is preferred), adds phenyl azide reluctantly to give a 15 : 2 : 2 : 1 mixture of adducts, where addition to the CFCFN bond predominates, gives a 3 : 1 mixture of trans- and cis-exo-3,4-dibromides, and is catalytically reduced to 2-ethoxycarbonyl-1,4,5,6,7-pentafluoro-2-azabicyclo[3.2.0]heptane.