C₂‐Symmetric 4,4′,5,5′‐Tetrahydrobi(oxazoles) and 4,4′,5,5′‐Tetrahydro‐2,2′‐methylenebis[oxazoles] as Chiral Ligands for Enantioselective Catalysis Preliminary Communication

The synthesis of a series of enantiomerically pure, C 2 ‐symmetric 4,4′,5,5′‐tetrahydro‐2,2′‐methylenebis[oxazoles] and 4,4′,5,5′‐tetrahydro‐2,2′‐bi(oxazoles) is reported. Copper complexes with anionic tetrahydromethylenebis[oxazole] ligands are efficient catalysts for the enantioselective cyclopropane formation from olefins and diazo compounds (up to 96% ee in the reaction of styrene with menthyl diazoacetate). Tetrahydrobi(oxazole)iridium(I) complexes were found to catalyze transfer hydrogenations of aryl alkyl ketones with i‐PrOH (up to 91% ee). Tetrahydrobi(oxazole)palladium complexes can be used as enantioselective catalysts for allylic nucleophilic substitution (up to 77% ee in the reaction of PhCHCHCH(OAc)Ph with NaHC(COOMe) 2 ).