Ytterbium(III) triflate-catalyzed asymmetric nucleophilic addition of functionalized lithium (α-carbalkoxyvinyl)cuprates to chiral p- toluenesulfinimines (thiooxime S-oxides)

Ytterbium(III) triflate has been found to catalyze anionic additions of functionalized lithium (α-carbalkoxyvinyl)cuprates to chiral p- toluenesulfinimines (thiooxime S-oxides) in a cosolvent system (Et₂O- CH₂Cl₂). This new system has made it possible to utilize those p- toluenesulfinimines of low solubility in Et₂O as the electrophiles to react with anionic (α-carbalkoxyvinyl)cuprates for the asymmetric synthesis of the corresponding β-mono and β,β-disubstituted Baylis-Hillman adducts. Modest yields (51.0-64.4% yield) and good to excellent diastereoselectivities (>90% de) were obtained.