Reactions of (E)-1,2-di(3-guaiazulenyl)ethylene and 2-(3-guaiazulenyl)-1,1-bis(4-methoxyphenyl)ethylene with tetracyanoethylene (TCNE) in benzene: comparative studies on the products and their spectroscopic properties

Abstract Reactions of the title ethylene derivatives, ( E )-1,2-di(3-guaiazulenyl)ethylene ( 1 ) and 2-(3-guaiazulenyl)-1,1-bis(4-methoxyphenyl)ethylene ( 2 ), with a 2 M amount of TCNE in benzene at 25 °C for 24 h under argon give new cycloaddition compounds, 1,1,2,2,11,11,12,12-octacyano-3-(3-guaiazulenyl)-8-isopropyl-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[ a ]azulene ( 3 ) from 1 and 1,1,2,2,11,11,12,12-octacyano-8-isopropyl-3,3-bis(4-methoxyphenyl)-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[ a ]-azulene ( 4 ) from 2 , respectively, in 66 and 87% isolated yields. Comparative studies on the above reactions as well as the spectroscopic properties of the unique products 3 and 4 , possessing interesting molecular structures, are reported and, further, a plausible reaction pathway for the formation of these products is described.