Unusual Reactivities of ortho -Hydroxy-β-nitrostyrene.

Nitrostyrene derivatives are widely used in organic syntheses as a substrate for Michael addition, photoisomerization and cycloaddition. In contrast, ortho -hydroxy derivatives exhibit unusual behaviors in these reactions. Conjugate addition proceeded upon treatment of the ortho -hydroxy-β-nitrostyrene with an amine; however, subsequent C-C bond cleavage readily occurred to afford the corresponding imine. Moreover, conversion of the trans -isomer to a cis -isomer did not occur efficiently, even when UV light was irradiated. We studied these unusual behaviors of β-nitrostyrene, focusing on the role of the ortho -hydroxy group.