Efficient and Convenient Access to Optically Active Tetrafluoroethylenated Amines Based on [1,3]-Proton Shift Reaction

Treatment of various ( R )- N -(2,2,3,3-tetrafluoropent-4-en-1-ylidene)-1-phenylethylamine derivatives with 2.4 equiv. of DBU in toluene at room temperature to 50 °C for 24 h led to a smooth [1,3]-proton shift reaction with a high chirality transfer, affording the corresponding rearranged products in acceptable yields. Without purification, these products were subjected to acid hydrolysis and the subsequent N -Cbz protection, providing the optically active tetrafluoroethylenated amides in moderate three-step yields.