The synthesis of constrained A, B- or A, Y-diamino acid derivatives as building blocks for new substituted 2,4-diaminobutyric acid derivatives is of great importance in medicinal and agricultural chemisrty. This research concerns the development of stereoselective syntheses and biochemical evaluation of new derivatives of 1,2-diaminocyclopropane-1-carboxylic acid and also the stufdy of their ring opening reactions towards potentially physiologically active amino acid derivatives.