| This thesis focuses on the asymmetric synthesis ofβ2-aminoxy acid and conformational studies ofβ2-aminoxy acids and hybrid peptides composed of a-aminoxy acids andβ-amino acids. In addition, the hybrid peptides are also employed to design hairpin structures. The main results are summarized below:First, we synthesized and obtained theβ2-aminoxy acid monomers and their dimers with methyl and iso-propyl side chain by amending the asymmetric synthetic route. And then we use 1HNMR, IR, CD and 2D NMR methods to study the secondary structures of these p2-aminoxy acid monomers and their dimers in organic solvents. The results clearly showed that a nine-membered-ring intramolecular hydrogen bond was formed between the C-terminal regular amide NH and the N-terminal carbonyl group, namelyβN-O turn. And X-ray and 2D NOE studies showed thatβ2-aminoxy acid monomer adopts two different conformations in organic solvents and at solid state, respectively, and the dimers form aβN-O helix in organic solvents. These studies have provided better understanding to the folding of peptides containingβ-aminoxy acids.We have carried out conformational studies of the hybrid oligomers composed ofα-aminoxy acids andβ-amino acids (1:1). The results indicated that an eight-member-ring intramolecular hydrogen bond was induced by a-aminoxy acids and these oligomers could form 8/8 helix in organic solvents. The side chains ofβ-amino acids were found to be able to influence the conformational stability of these oligomers. The oligomers composed of a-aminoxy acids andβ2,2-amino acids with cyclic-and acyclic-side chains were found to have a more stable secondary structure. These studies on the hybrid peptides have provided more structural elements to simulate natural proteins.We have investigated another hybrid backbone. When two naturalα-amino acids were linked in the N-and C-terminus of a dipeptide composed of D-α-aminoxy acid...
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