An atom- and step-economical C(sp³)–H addition of N,N-dimethyl anilines to various sterically demanding 1,1- and 1,2-disubstituted alkenes has been achieved by using a simple β-diketiminato ligand supported scandium dialkyl complex in combination with a borate compound. The corresponding C(sp³)–C(sp³) bond forming reaction occurs with excellent regioselectivities to give a variety of tertiary aromatic amines.