Enantioselective Synthesis Of Planar Chiral Ferrocene [1,2-d]-2-Pyrrolidone Derivatives

Planar chiral ferrocene has been widely used in many fields because of its special structure and stability.In this paper,the direct formation of planar chiral ferrocene[1,2-d]-2-pyrrolidone derivatives was studied by palladium-catalyzed intramolecular asymmetric C(sp2)-H bond activation.Using ferrocene formic acid as a raw material,it is obtained through acyl chloride,azide,ammoniation,and reduction to obtain ferrocene amine.After dehydration condensation with phenyl propiolate,the amine group is finally protected with methyl iodide.The catalytic reaction substrate is obtained.After the templating reaction established,the effects of ligands,temperature,and palladium source on the reaction were examined through experiments,and various types of chiral ligands were extensively screened,among which the phosphoramidite ligands of the tartaric acid skeleton.The reaction has its unique advantages.Therefore,a series of phosphoramidite chiral ligands of tartaric acid framework were synthesized and the catalytic efficiency and asymmetric induction effect were investigated.Finally,the best reaction conditions and the best chiral ligand were determined,and the substrate was expanded.Under the optimal conditions selected,the phenylpropargyl ferrocene reaction substrates with different substituents can all be smooth conversion and generation of planar chiral ferrocene [1,2-d]-2-pyrrolidone compounds with good selectivity,the best results achieved yields of up to 92% and ee values of up to 83%.