Construction of Bridged and Fused Ring Systems via Intramolecular Michael Reactions of Vinylnitroso Compounds

The first examples of intramolecular Michael-type reactions of in situ-formed vinylnitroso compounds with carbon nucleophiles are reported. This methodology has been used to prepare a variety of ring systems including [3.2.1]-, [2.2.2]-, and [2.2.1]-bridged carbobicyclic compounds, as well as a fused [5.5]-ring compound. Malonate anions have proven to be effective carbon nucleophiles in these conjugate addition reactions, and simple ester potassium enolates have also been successfully employed.