Intermolecular [4+2]-Cycloadditions of Nitroalkenes with Cyclic Olefins. Transformations of Cyclic Nitronates

Denmark, S. E.; Cramer, C. J.; Sternberg, J. A.
Helv. Chim. Acta 1986, 69, 1971.

Nitrocyclohexene undergoes facile SnCl₄-induced [4+2]-cycloadditions with simple cycloalkenes to produce nitronates. The nitronates can be transformed stereospecifically into a number of other functional groups (alcohol, ketone, oxime, amine) by hydrolytic, reductive, and oxidative processes. The mechanism of the [4+2]-cycloaddition is believed to involve formation of a zwitterionic intermediate which can collapse via competing pathways to form the observed products. 1,3-Dipolar cycloadditions of the nitronates are described.