850232-59-6Relevant articles and documents
An Improved Synthesis of Polyfunctional Acyl Azides in PEG 400
Widyan, Khalid
, p. 120 - 126 (2021/03/16)
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Non-phosgene route to unsymmetrical ureas from N-Cbz-α-amino acid amides
Ghazvini Zadeh, Ebrahim H.,Abo-Dya, Nader E.,Sotuyo, Ania C.,Ghiviriga, Ion,Hall, C. Dennis
, p. 5467 - 5469 (2013/09/23)
A convenient method toward the synthesis of α-amino acid-derived unsymmetrical ureas 2 is described herein. This route involves an interesting rearrangement of amides of N-Cbz-α-amino acids 1, which presumably entails the intermediacy of hydantoins that is followed by hydrolysis to afford unsymmetrical ureas 2 in quantitative yields and high purity.
Chemical ligation of S-scylated cysteine peptides to form native peptides via 5-, 11-, and 14-membered cyclic transition states
Katritzky, Alan R.,Tala, Srinivasa R.,Abo-Dya, Nader E.,Ibrahim, Tarek S.,El-Feky, Said A.,Gyanda, Kapil,Pandya, Keyur M.
experimental part, p. 85 - 96 (2011/04/12)
Cysteine-containing dipeptides 3a-l, (3b+3b′) (compound numbers in parentheses are used to indicate racemic mixtures; thus (3b+3b′) is the racemate of 3b and 3b′), and tripeptide 13 were synthesized in 68-96% yields by acylation of cysteine with N-(Pg-α-aminoacyl)- and N-(Pg-α-dipeptidoyl)benzotriazoles (where Pg stands for protecting group in the nomenclature for peptides throughout the paper) in the presence of Et3N. Cysteine-containing peptides 3a-l and 13 were S-acylated to give S-(Pg-α-aminoacyl)dipeptides 5a-l and S-(Pg-α-aminoacyl) tripeptide 14 without racemization in 47-90% yields using N-(Pg-α- aminoacyl)benzotriazoles 2 in CH3CN-H2O (7:3) in the presence of KHCO3. (In our peptide nomenclature, the prefixes di-, tri-, etc. refer to the number of amino acid residues in the main peptide chain; amino acid residues attached to sulfur are designated as S-acyl peptides. Thus we avoid use of the prefix "iso".) Selective S-acylations of serine peptide 3k and threonine peptide 3l containing free OH groups were thus achieved in 58% and 72% yield, respectively. S-(Pg-α-aminoacyl)cysteines 4a,b underwent native chemical ligations to form native dipeptides 3f,i via 5-membered cyclic transition states. Microwave irradiation of S-(Pg-α-aminoacyl)tripeptide 15 and S-(Pg-α-aminoacyl)tetrapeptide 17 in the presence of NaH2PO4/Na2HPO 4 buffer solution at pH 7.8 achieved chemical ligations, involving intramolecular migrations of acyl groups, via 11- and 14-membered cyclic transition states from the S-atom of a cysteine residue to a peptide terminal amino group to form native peptides 19 and 20 in isolated yields of 26% and 23%, respectively.
