Lewis Acid-Promoted Conjugate Addition of Dienol Silyl Ethers to Nitroalkenes:  Synthesis of 3-Substituted Azepanes

A novel γ-selective conjugate addition of 1-silyl-substituted dienol ethers to nitroalkenes activated by Lewis acids has been developed. The resulting α,β-unsaturated acylsilanes undergo photoinduced protodesilylation to afford the corresponding enals, which can be conveniently transformed into azepanes under appropriate reductive conditions.