title: Crystal structure of N-(tert-but-oxy-carbon-yl)phenyl-alanylde-hydro-alanine isopropyl ester (Boc-Phe-ΔAla-OiPr).
abstract: In the title compound, the de-hydro-dipeptide (Boc-Phe-ΔAla-OiPr, C20H28N2O5), the mol-ecule has a trans conformation of the N-methyl-amide group. The geometry of the de-hydro-alanine moiety is to some extent different from those usually found in simple peptides, indicating conjugation between the H2C=C group and the peptide bond. The bond angles around de-hydro-alanine have unusually high values due to the steric hindrance, the same inter-action influencing the slight distortion from planarity of the de-hydro-alanine. The mol-ecule is stabilized by intra-molecular inter-actions between the isopropyl group and the N atoms of the peptide main chain. In the crystal, an N-H⋯O hydrogen bond links the mol-ecules into ribbons, giving a herringbone head-to-head packing arrangement extending along the [100] direction. In the stacks, the mol-ecules are linked by weak C-H⋯O hydrogen-bonding associations.
authors.affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.
authors.forename: Paweł
authors.initials: P
authors.lastname: Lenartowicz
authors.affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Makowski
authors.affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Zarychta
authors.affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Ejsmont
keywords: crystal structure; de­hydro peptides; de­hydro­alanine; herringbone packing; α,β-de­hydro­amino acids