Crystal structure of Boc-(S)-ABOC-(S)-Ala-(S)-ABOC-(S)-Phe-OBn chloroform monosolvate

Abstract

In the title compound, phenyl (S)-2-[(S)-(1-{2-[(S)-(1-{[(tert-butoxy)carbonyl]amino}bicyclo[2.2.2]octan-2-yl)formamido]propanamido}bicyclo[2.2.2]octan-2-yl)formamido]-3-phenylpropanoate chloroform monosolvate, C42H56N4O7·CHCl3, the α,β-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...H—N hydrogen bonds. In the crystal, the oligomers are linked by N—H...O=C hydrogen bonds into chains along the a-axis direction. The chloroform solvent molecules are intercalated between the folded chains via C—H...O=C interactions.

Keywords

• crystal structure
• α,β-hybrid peptide
• (S)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid
• (S)-ABOC
• (S)-Ala
• (S)-Phe
• Boc
• OBn
• 11/9 helix
• hydrogen bonding