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

Nitrocyclohexene undergoes facile SnCl₄‐induced, [4 + 2]‐cycloadditions with simple cycloalkenes to produce nitronates. The nitronates can be transformed sterospecifically 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.