A facile synthetic method of α-quaternary-β,γ-unsaturated aldehydes via the stereoselective 1,4-elimination and α-regioselective Ferrier reaction

The 1,4-elimination reaction of 2-substituted-(2Z)-4-methoxy-O-alkenyl acetals with n-butyllithium is shown to afford the 2-substituted-(1Z,3E)-O-1,3-dienyl acetals in high stereoselectivities. The Ferrier reaction of the O-1,3-dienyl acetals thus obtained provides the corresponding α-quaternary-β,γ-unsaturated aldehydes in excellent yields with high α-regioselectivities.