Asymmetric Vinylogous Mukaiyama-Type Aldol Reactions with Sulfoximine Ligands

Significance

The authors report a novel asymmetric vinylogous Mukaiyama aldol reaction catalyzed by Cu(II) complexes bearing C1-symmetric aminosulfoximines. It has been found that the catalyst turnover benefits from the presence of CF₃CH₂OH as additive (yield increased from 66-92%). Among various Cu(II) salts, Cu(OTf)₂ was the only one that gave both high enantiomeric excess and good yield. Catalyst loadings of 5 mol% and 1 mol% led to lower product yields (64% and 60%, respectively). Varying the size of carbonyl esters 1 had only a minor effect.