Asymmetric catalytic conjugate addition of acetaldehyde to nitrodienynes/nitroenynes: applications to the syntheses of (+)-α-lycorane and chiral β-alkynyl acids.

Abstract

The catalytic enantioselective conjugate addition of acetaldehyde to polyconjugated substrates, nitrodienynes and nitroenynes, has been accomplished using organocatalysis. Various functionalized 1,3-enynes and propargylic compounds were obtained in moderate to good yields with high enantioselectivity. The synthetic utilities of the conjugate addition reactions have been highlighted in the concise total synthesis of (+)-α-lycorane and the metal-free synthesis of chiral β-alkynyl acids.