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Crystal structure of N-(tert-but-oxy-carbon-yl)phenyl-alanylde-hydro-alanine isopropyl ester (Boc-Phe-ΔAla-OiPr).

Lenartowicz P, Makowski M, Zarychta B, Ejsmont K - Acta Crystallogr Sect E Struct Rep Online (2014)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.

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.

No MeSH data available.


Related in: MedlinePlus

The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr) showing 50% displacement ellipsoids. Intra­molecular C—H⋯O inter­actions are shown as dashed lines.
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fig1: The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr) showing 50% displacement ellipsoids. Intra­molecular C—H⋯O inter­actions are shown as dashed lines.

Mentions: The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr, C20H28N2O5) is shown in Fig. 1 ▶. The mol­ecule has a trans-conformation of the N-methyl­amide group. The geometry of the de­hydro­alanine is to some extent different from those usually found in simple peptides (Pauling, 1960 ▶). In particular, the N19—C20 bond length is shorter while C17—N19 is longer [1.402 (3) Å and 1.354 (3) Å, respectively]. This is in excellent agreement with the values reported for N-acetyl­dehydro­alanine (Ajó et al., 1979 ▶), N-acetyl­bis-(de­hydro­phenyl­alanyl)glycine (Pieroni et al. 1975 ▶) and N-acetyl­ode­hydro­di­­meth­yl­amide (Rzeszotarska et al., 2002 ▶) and seems to be typical for α, β-unsaturated peptide systems (Jain & Chauhan, 1996 ▶). This indicates conjugation between the H2C=C group and the peptide bond. The valance angles around de­hydro­alanine have unusually large values [C21—C20—N19 = 126.9 (2), C17—N19—C20 = 126.8 (2) and O18—C17—N19 = 123.5 (2)°] due to the steric hindrance between atoms C21 and O18. The same inter­action influences the slight distortion from planarity of the de­hydro­alanine moiety. The ω, ϕ and ψ torsion angles (C9—C17—N19—C20, C17—N19—C20—C22 and N19—C20—C22—O24, respectively) of the de­hydro­alanine residue are −166.9 (2), 175.1 (2) and 178.0 (2)°. The geom­etries of the phenyl­aniline and the protecting groups are normal. There are four intra­molecular C—H⋯O close contacts but three of them have a D—H⋯A angle of less than 120°.


Crystal structure of N-(tert-but-oxy-carbon-yl)phenyl-alanylde-hydro-alanine isopropyl ester (Boc-Phe-ΔAla-OiPr).

Lenartowicz P, Makowski M, Zarychta B, Ejsmont K - Acta Crystallogr Sect E Struct Rep Online (2014)

The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr) showing 50% displacement ellipsoids. Intra­molecular C—H⋯O inter­actions are shown as dashed lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257372&req=5

fig1: The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr) showing 50% displacement ellipsoids. Intra­molecular C—H⋯O inter­actions are shown as dashed lines.
Mentions: The mol­ecular structure of N-(tert-but­oxy­carbon­yl)phenyl­alanylde­hydro­alanine isopropyl ester (Boc–Phe–ΔAla–OiPr, C20H28N2O5) is shown in Fig. 1 ▶. The mol­ecule has a trans-conformation of the N-methyl­amide group. The geometry of the de­hydro­alanine is to some extent different from those usually found in simple peptides (Pauling, 1960 ▶). In particular, the N19—C20 bond length is shorter while C17—N19 is longer [1.402 (3) Å and 1.354 (3) Å, respectively]. This is in excellent agreement with the values reported for N-acetyl­dehydro­alanine (Ajó et al., 1979 ▶), N-acetyl­bis-(de­hydro­phenyl­alanyl)glycine (Pieroni et al. 1975 ▶) and N-acetyl­ode­hydro­di­­meth­yl­amide (Rzeszotarska et al., 2002 ▶) and seems to be typical for α, β-unsaturated peptide systems (Jain & Chauhan, 1996 ▶). This indicates conjugation between the H2C=C group and the peptide bond. The valance angles around de­hydro­alanine have unusually large values [C21—C20—N19 = 126.9 (2), C17—N19—C20 = 126.8 (2) and O18—C17—N19 = 123.5 (2)°] due to the steric hindrance between atoms C21 and O18. The same inter­action influences the slight distortion from planarity of the de­hydro­alanine moiety. The ω, ϕ and ψ torsion angles (C9—C17—N19—C20, C17—N19—C20—C22 and N19—C20—C22—O24, respectively) of the de­hydro­alanine residue are −166.9 (2), 175.1 (2) and 178.0 (2)°. The geom­etries of the phenyl­aniline and the protecting groups are normal. There are four intra­molecular C—H⋯O close contacts but three of them have a D—H⋯A angle of less than 120°.

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland.

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.

No MeSH data available.


Related in: MedlinePlus