Photochemical deazetation of 2,3-diazabicyclo[2.2.2]oct-2-ene: pseudorotation of the cyclohexanediyl biradical

Abstract

Direct irradiation of cis-anti-[5,6-²H₂]-2,3-diazabicyclo [2.2.2]oct-2-ene leads to bicyclohexane in which the deuterium is predominantly exo, i.e. with inversion of configuration, to hexadiene in which most, but not all, of the vinylic deuterium is present in the E,Z-isomer, and to cyclohexene lacking vinylic deuterium. Qualitatively similar results were obtained for the sensitised irradiation. The results are discussed in terms of a scheme in which cleavage of one C–N bond is followed by conformational changes in a diazenyl biradical, and then in a cyclohexanediyl biradical.