A modification and details of the palladium-catalyzed tert-butoxycarbonylation of 2,2,2-trifluoroacetimidoyl iodides 1, which gave the iminocarboxylates 2, one of the promising precursors to fluorinated alpha-amino acids, are described. The Pd-catalyzed carbonylation reaction was remarkably promoted by the use of DMF or DMI as an additive, enough to achieve the selective formation of tert-butyl iminoesters. Nucleophilic alkylation of the imine moiety of 2 and subsequent removal of N- and O-protecting groups gave a variety of 2-substituted 2-amino-3,3,3-trifluoropropanoic acid derivatives 3 in high yields.