(2+2)-photocycloaddition of ethylene to 1, 2-dicyanocyclobutene. 2 isomerizes cleanly to 2, 5-dicyanohexadiene-1, 5 (3) with a very low activation energy of 21.7 ± 1.4 kcal/mol. From comparison with the reported rates of isomerization of bicyclo[2.2.0]hexane, the radical stabilization energy of the cyano group is shown to be about 7.3 kcal/mol.
通过将
乙烯(2 + 2)-光环加成至1,2-二
氰基
环丁烯来制备1,4-二
氰基双环[2.2.0]己烷(2)。2干净地异构化为2,5-二
氰基
己二烯-1,5(3),活化能非常低,仅为21.7±1.4 kcal / mol。与所报道的双环[2.2.0]己烷的异构化速率相比,
氰基的自由基稳定能显示为约7.3 kcal / mol。