Bis(2-acetoxyacrylonitrile) and Its Phenylene and Alkylene Bis Homologues. Preparation, Isomerization, and Intramolecular Photocycloaddition

Article abstract of DOI:10.1021/jo00034a015

The title compounds, 1,4-diacetoxy-1,4-dicyano-1,3-butadiene (3), 1,6-diacetoxy-1,6-dicyano-1,5-hexadiene (8), 1,2-bis(2-acetoxy-2-cyanovinyl)benzene (13), and 1,4-bis(2-acetoxy-2-cyanovinyl)benzene (17) were prepared by acetylation of the corresponding diacyl dicyanides.Dicyanides were prepared from diacyl chlorides by reaction with cyanotrimethylsilane or the NaI-Cu2(CN)2 reagent.Among the three geometrical isomers of the title compounds, the Z,Z diene predominated in 8 whereas E,E dienes predominated in conjugated dienes 3, 13, and 17.Conjugated E,E dienes underwent photoisomerization to E,Z and Z,Z isomers much faster than unconjugated diene 8.Prolonged irradiation of 13 yielded intramolecular <2 + 2> cycloadducts endo,exo- and exo,exo-5,6-diacetoxy-5,6-dicyano-2,3-benzobicyclo<2.1.1.>hex-2-ene (22).Photochemistry in the formation of 22 is discussed.