A Method for the Synthesis of 3,3-Diarylallyl Amines from Propargyl Benzyl Amines: Evidence for An allyl Iminium Intermediate During the Cationic [1,5]-Aryl Migration

The 3,3-diarylallyl amines as well as propyl amines are very important and privileged scaffolds in medicinal chemistry and synthetic organic chemistry. Here we report a synthetic approach for the rapid and stereoselective construction of 2-halo-3,3-diarylallyl amines from corresponding propargyl benzyl amines and NXS reagents. This method was found to be compatible for a broad range of propargyl benzyl amines and NXS reagents (X = I, Br, Cl). This reaction employs water as the co-solvent as well as sole-promoter, in the absence of any additives. Intercepting the reaction progress and analyzing the crude reaction mixture by 1 H-NMR and HRMS spectroscopic techniques, evidenced the existence of water as well as succinimide trapped allyl amines. These structures in turn suggest the presence of the corresponding allyl iminium intermediate, during the cationic [1,5]-aryl migration.