Pseudopeptide fragments and local structures induced by an α-aminoxy acid in a dipeptide
摘要:
An alpha-aminoxy acid residue has been introduced by liquid-phase procedures in a model dipeptide, by means of the amidoxy (CO-NH-O), oxime (CH=N-O) and hydroxylamine (CH2-NH-O) pseudopeptide link. The structural properties induced by the three amide surrogates, which are not protonated at the physiological pH, have been studied in organic solution. In all three cases, the oc-oxygen interacts with the adjacent amide NH to close a five-membered cycle. The amidoxy link gives rise to a very stable bt-like folded structure and the cis-oxime link to a beta-like folded structure. (C) 2000 Elsevier Science Ltd. All rights reserved.
Pseudopeptide fragments and local structures induced by an α-aminoxy acid in a dipeptide
摘要:
An alpha-aminoxy acid residue has been introduced by liquid-phase procedures in a model dipeptide, by means of the amidoxy (CO-NH-O), oxime (CH=N-O) and hydroxylamine (CH2-NH-O) pseudopeptide link. The structural properties induced by the three amide surrogates, which are not protonated at the physiological pH, have been studied in organic solution. In all three cases, the oc-oxygen interacts with the adjacent amide NH to close a five-membered cycle. The amidoxy link gives rise to a very stable bt-like folded structure and the cis-oxime link to a beta-like folded structure. (C) 2000 Elsevier Science Ltd. All rights reserved.
Efficient Preparation of Aminoxyacyl Amides, Aminoxy Hybrid Peptides, and α-Aminoxy Peptides
作者:Alan R. Katritzky、Ilker Avan、Srinivasa R. Tala
DOI:10.1021/jo901612j
日期:2009.11.20
N-(Pg-α-aminoxy acids) 1a−g are converted to N-(Pg-α-aminoxyacyl)benzotriazoles 2a−g, which react under mild conditions with amines, α-amino acids/α-dipeptides, and α-aminoxy acids to give aminoxyacyl amides 3a−g, (3e+3e′), and (3g+3g′), aminoxy hybrid peptides 4a−h, (4a+4a′), 6a−d, 9a−e, (9a+9a′), and (9b+9b′), and α-aminoxy peptides 10a,b in good yields without racemization.
The pseudodipeptide, (S)-N-isopropyl [N-(pivaloyl)pyrrolidin-2-yl]methylaminooxy}acetamide, C15H29N3O3, adopts a global extended conformation with the hydroxylamine group in the g(+)/g(-) structure. The C-terminal amide NH interacts intramolecularly with the hydroxylamine O atom. Both NH bonds of each molecule are hydrogen bonded to the C-terminal amide carbonyl of a neighbouring molecule.