Preparation and conformational analysis of C-glycosyl β2- and β/β2-peptides

Ten C -glycosyl β 2 - and β/β 2 - peptides with three to eight amino acid residues have been prepared. Solution and solid-phase peptide syntheses were employed to assemble β 2 -amino acids in which C -glycosylic substituents are attached to the C-2 position of β-amino acids. Conformational analysis of the C -glycosyl β 2 -peptides using NMR and CD spectra indicates that the tripeptide can form a helical secondary structure. Besides, helix directions of the C -glycosyl β/β 2 -peptides are governed by the configuration at the α-carbon of the peptide backbone that originates from the stereocenter of the C -glycosyl β 2 -amino acids.