In:
Acta Crystallographica Section E Crystallographic Communications, International Union of Crystallography (IUCr), Vol. 71, No. 1 ( 2015-01-01), p. 113-116
Abstract:
The title compound, cyclo (Phe 1 –D-Ala 2 –Gly 3 –Phe 4 –APO 5 ), C 26 H 32 N 4 O 5 , is the minor diastereoisomer of a cyclic penta-peptidomimetic analogue containing a novel 2-aminopropyl lactone (APO) motif, which displays the same number of atoms as the native amino acid glycine and has a methyl group in place of the carbonyl O atom. The crystal structure presented here allows the analysis of the secondary structure of this unprecedented cyclic carbo-isosteric depsipeptide. The conformation of the central ring is stabilized by an intramolecular N—H...O hydrogen bond between the carbonyl O atom of the first residue (Phe 1 ) and the amide group H atom of the fourth residue (Phe 4 ). Based on the previously reported hydrogen bond and on the values of the torsion angles ϕ and ψ, the loop formed by the first, second, third and fourth residues (Phe 1 , D-Ala 2 , Gly 3 and Phe 4 ) can be classified as a type II′ β-turn. The loop around the new peptidomimetic motif, on the other hand, resembles an open γ-turn containing a weak N—H...O hydrogen bond between the carbonyl group O atom of the fourth residue (Phe 4 ) and the amide unit H atom of the first residue (Phe 1 ). In the crystal, the peptidomimetic molecules are arranged in chains along the b- axis direction. Within such a chain, the molecules of the structure are linked via N—H...O hydrogen bonds between the amide group H atom of the secondary residue (D-Ala 2 ) and the carboxy unit O atom of the fourth residue (Phe 4 ) in a neighboring molecule. The newly formed methyl stereocentre of the APO peptidomimetic motif (APO 5 ) was obtained as the minor diastereoisomer in a ring-closing reductive amination reaction and adopts an R configuration.
Type of Medium:
Online Resource
ISSN:
2056-9890
DOI:
10.1107/S2056989014027406
DOI:
10.1107/S2056989014027406/lh5744sup1.cif
DOI:
10.1107/S2056989014027406/lh5744Isup2.hkl
DOI:
10.1107/S2056989014027406/lh5744Isup3.cml
Language:
Unknown
Publisher:
International Union of Crystallography (IUCr)
Publication Date:
2015
detail.hit.zdb_id:
2843762-7
detail.hit.zdb_id:
2041947-8
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