Lewis acid-promoted conjugate addition of dienol silyl ethers to nitroalkenes: Synthesis of 3-substituted azepanes

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