Abstract
In the title compound, phenyl (S)-2-[(S)-(1-\2-[(S)-(1-\[(tert-butoxy)carbonyl]amino\bicycloĂ [2.2.2]octan-2-yl)formamido]propanamido\bicyclo[2.2.2]octan-2-yl)for mamido]-3-phenylpropanoate chloroform monosolvate, C42H56N4O7-CHCl3, the alpha,beta-hybrid peptide contains two non-proteinogenic amino acid residues of (S)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid [(S)-ABOC], two amino acid residues of (S)-2-aminopropanoic acid [(S)-Ala] and (S)-2-amino-3-phenylpropanoic acid [(S)-Phe], and protecting groups of tert-butoxycarbonyl (Boc) and benzyl ester (OBn). The tetramer folds into a right-handed mixed 11/9 helix stabilized by intramolecular i, i +3 and i, i-1 C=O center dot center dot center dot H-N hydrogen bonds. In the crystal, the oligomers are linked by N-H center dot center dot center dot O=C hydrogen bonds into chains along the a-axis direction. The chloroform solvent molecules are intercalated between the folded chains via C-H center dot center dot center dot O=C interactions.