The (R) α-branched β-amino acid derivatives 3-5 with the side chains of alanine, valine and leucine are prepared by amino-methylation of acyloxazolidinones 2a-c and are used for the synthesis of the trifluoroacetate salt 9 of H(-β2-HVal-β2-HAla-β2-HLeu)2-OH. The CD spectrum of compound 9 is compared with that of the isomer H(-β3-HVal-β3-HAla-β3-HLeu)2-OH (1) built from the corresponding β-branched β-amino acids.