- Metal-free approach for hindered amide-bond formation with hypervalent iodine(iii) reagents: application to hindered peptide synthesis
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A new bio-inspired approach is reported for amide and peptide synthesis using α-amino esters that possess a potential activating group (PAG) at the ester residue. To activate the ester functionality under mild metal-free conditions, we exploited the facile dearomatization of phenols with hypervalent iodine(iii) reagents. Using a pyridine-hydrogen fluoride complex, highly reactive acyl fluoride intermediates can be successfully generated, thereby allowing for the smooth formation of sterically hindered amides and peptides from bulky amines and α-amino esters, respectively.
- Lee, Hyo-Jun,Huang, Xiao,Sakaki, Shigeyoshi,Maruoka, Keiji
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p. 848 - 855
(2021/02/09)
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- ROLE OF AMINO ACID RESIDUES IN CHROMOGENIC SUBSTRATES CLEAVED BY PANCREATIC ELASTASE
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Anionic chromogenic substrates, 3-carboxypropionyl tripeptide p-nitroanilides modified with glycine, β-alanine, alanine, leucine, and proline in positions P1, P2, and P3 were synthesized.The substrates were digested with pancreatic elastase and the values of Km, kcat, and kcat/Km were determined.Alanine plays a decisive role in position P1, substrates with glycine or β-alanine in this position are not cleaved.The substitution in P2 is dominant for proline; next follow alanine, leucine, and glycine.The substitution in P3 is the least specific one.
- Kasafirek, Evzen,Fric, Premysl,Slaby, Jan
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p. 1625 - 1633
(2007/10/02)
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