Synthesis of nitrogen-functionalized cyclohexanes using chemoselective conjugate addition of phenyllithium to linear ω-nitro-α,β, ψ,ω-unsaturated ester and subsequent stereoselective intramolecular nitro-Michael cyclization

Abstract

Nitrogen-functionalized cyclohexane derivatives with three contiguous chiral centers were synthesized by nitroalkene-selective conjugate addition of phenyllithium to a ω-nitro-α,β,ψ, ω-unsaturated ester and subsequent stereocontrolled intramolecular nitro-Michael cyclization with cesium fluoride and a quaternary ammonium bromide. The cyclohexanes were applicable to the total synthesis of α-, β- and γ-lycoranes. © 2004 Pharmaceutical Society of Japan.