Crystal structure of the tripeptide N-(benzyl­oxycarbon­yl)glycylglycyl-l-norvaline

摘要

The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The mol­ecule has a Gly–Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has a g+t conformation. In the crystal lattice, N—H⋯O and O—H⋯O hydrogen bonds stabilize the packing. Mol­ecules translated along the crystallographic a axis associate through an N—H⋯O hydrogen bond. The remaining three hydrogen bonds are between mol­ecules related by a 21 screw axis.