15136-30-8Relevant academic research and scientific papers
Chiral Overpass Induction in Dynamic Helical Polymers Bearing Pendant Groups with Two Chiral Centers
Freire, Félix,Qui?oá, Emilio,Riguera, Ricardo,Suárez-Picado, Esteban
, p. 4537 - 4543 (2020)
The dynamic behavior of helical polymers bearing pendant groups with two chiral centers was studied. Controlled conformational changes at the chiral units placed either closer to or further away from the main chain promote different helical structures. Al
Amino Acid Chirality and Ferrocene Conformation Guided Self-Assembly and Gelation of Ferrocene-Peptide Conjugates
Adhikari, Bimalendu,Singh, Charanpreet,Shah, Afzal,Lough, Alan J.,Raatz, Heinz-Bernhard
supporting information, p. 11560 - 11572 (2015/08/03)
The self-assembly and gelation behavior of a series of mono- and disubstituted ferrocene (Fc)-peptide conjugates as a function of ferrocene conformation and amino acid chirality are described. The results reveal that ferrocene-peptide conjugates self-asse
Preparation of (R)-2-azidoesters from 2-((p-nitrobenzene)sulfonyl)oxy esters and their use as protected amino acid equivalents for the synthesis of di- and tripeptides containing D-amino acid constituents
Hoffman,Kim
, p. 3007 - 3020 (2007/10/02)
(R)-2-Azidoesters and their derived (R)-2-azido acids are readily prepared from common amino acids by an inversion methodology that employs (S)-2-nosyloxyesters as key intermediates. The (R)-2-azidoesters can be used as protected amino acid equivalents in peptide synthesis. Basic hydrolysis frees the carboxyl group. Triphenylphosphine/water is used to free the amine group. By these reactions a variety of L-D and D-L dipeptides, L-D-L tripeptides, and depsipeptides can be prepared easily in good yields, and without detectable epimerization.
Transesterifications with 1,8-Diazabicycloundec-7-ene/Lithium Bromide (DBU/LiBr) - Also Applicable to Cleavage of Peptides from Resins in Merrifield Syntheses
Seebach, Dieter,Thaler, Adrian,Blaser, Denis,Ko, Soo Y.
, p. 1102 - 1118 (2007/10/02)
A mixture of the amidine base 1,8-diazabicycloundec-7-ene (DBU) and LiBr (preferably 0.5 and 5 equiv., resp.) turns out to be a highly efficient catalyst (at 0-25 deg C) for saponifications (in THF/H2O) and transesterifications (in ROH).The scope and limitations of the method are determined using ca. two dozens of different ester/alcohol combinations (Schemes 2 and 3).The investigation is focused on peptides as substrates.Under carefully controlled conditions, no epimerization occurs with N-Boc- and N-Z-protected peptide esters, when methyl, ethyl, isopropyl, or allyl esters are the products, as shown for peptides containing up to six amino acids, with Ala, Leu, MeLeu, Asp(OEt), or Tyr at the C-terminus (Scheme 3 and Tables 1 and 2).Hydrolytic and transesterifying detachments of Boc-Leu-Ala-Gly-Val-OR and Boc-Leu-Ala-Gly-Phe-OR (R = H, Me) from PAM and Wang resins (1-8 h at 0-25 deg C, 2 equiv. of DBU, 5 equiv. of LiBr) can be achieved by this method without epimerization of the C-terminal stereogenic center; a comparison with other methods (HF, Ti(OR)4) is given (Schemes 4 and 5).Possible protecting-group strategies involving the DBU/LiBr method are discussed (Table 3).Extensive experimental details are given.
