Asymmetric Arylation of Ketones with Chiral NHC Modified Fe₃O₄/Pd Nanoparticles

Significance

Chiral N-heterocyclic carbene modified Fe₃O₄/palladium nanoparticles (Fe₃O₄/Pd NPs-L) were prepared by impregnation of K₂[PdCl₄] to Fe₃O₄ nanoparticles in the presence of NaBH₄ followed by treatment with L˙HBF₄ and NaOt-Bu (eq. 1). The asymmetric α-arylation of 1a with bromo- or chlorobenzene proceeded in the presence of Fe₃O₄/Pd NPs-L and NaOt-Bu to give 2a in 72 or 56% yield with 48 or 60% ee (eq. 2). The chiral nanoparticles were also generated in situ by mixing Fe₃O₄/Pd NPs, L˙HBF₄ and NaOt-Bu to achieve the asymmetric α-arylation of ketones (eq. 3, 11 examples; 56-91% yield with 33-85% ee).