Transformation of C-terminal serine and threonine extended precursors into C-terminal .alpha.-amidated peptides: a possible chemical model for the .alpha.-amidating action of pituitary enzymes
作者:Darshan Ranganathan、Sujata Saini
DOI:10.1021/ja00003a048
日期:1991.1
The chemical model presented here affords a mild and practical methodology for the preparation of C-terminal amides from C-terminal Ser/Thr extended precursors. Further, the oxalamides derived from N-terminal and nonterminal Ser/Thr peptides constitute an entirely novel class of peptide analogues possessing extended planar bis-peptide regions, the study of whose conformational and reactivity profile
此处介绍的化学模型为从 C 端 Ser/Thr 扩展前体制备 C 端酰胺提供了一种温和实用的方法。此外,源自 N 末端和非末端 Ser/Thr 肽的草酰胺构成了一类全新的肽类似物,具有扩展的平面双肽区域,其构象和反应性特征的研究将证明是有趣的
Concise Synthesis of 2,5-Diketopiperazines via Catalytic Hydroxy-Directed Peptide Bond Formations
concise synthesis of this type of DKPs through diboronic acid anhydride-catalyzed hydroxy-directed peptidebondformations. The sequential reactions in this report, which consist of three steps, an intermolecular catalytic condensation reaction in which water is the only byproduct, a simple deprotection of the nitrogen-protecting group, and an intramolecular cyclization, enabled the synthesis of functionalized
Hydroxy-directed peptide bond formation from α-amino acid-derived inert esters enabled by boronic acid catalysis
作者:Naoya Takahashi、Airi Takahashi、Naoyuki Shimada
DOI:10.1039/d3cc04856j
日期:——
acid-catalyzed peptidebondformation from α-amino acid methyl esters is described. The catalysis showed high chemoselectivity for β-hydroxy-α-amino esters, affording the peptides in high to excellent yields with high functional group tolerance. This hydroxy-directed peptidebondformation could be applicable to oligopeptide syntheses. This is the first successful example of organoboron-catalyzed peptide bond
Protein Backbone Modification by Novel C.alpha.-C Side-Chain Scission
作者:Darshan Ranganathan、Narendra K. Vaish、Kavita Shah
DOI:10.1021/ja00094a008
日期:1994.7
alpha-Ketoamide (-NH-CO-CO-) units in intact peptides are generated from Ser/Thr residues via Ru(VIII)catalyzed C-alpha-C side-chain scission. Facets associated with this novel cu-carbon modification have been probed with 75 peptides chosen to represent every possible peptide environment. The reactions were carried out at room temperature with in situ generated Ru(VIII) in biphasic (CH3CN/CCl4/pH 3 phosphate buffer, 1:1:2 v/v) medium. Whereas Ser/Thr residues placed at the C-terminal end in peptides undergo N-C bond scission leading to des-Ser/Thr peptide amides-thus acting as Gly equivalents in simulating the alpha-amidating action of pituitary enzymes-those located at the N-terminal or nonterminal or even at the C-terminal position (protected as amide) were found to undergo oxidative C-C bond scission (involving C-alpha and C side-chain bond), resulting in the generation of alpha-ketoamide (-NH-CO-CO-) units in the intact peptide backbone. The difference in the products arising from C-alpha-C side-chain scission of Ser/Thr esters and amides is rationalized on the basis of a common mechanism involving either oxaloesters [Pep-NH-CO-COX; X = OMe] or oxalamides [X = NH2 or NH-Pep] arising from the oxidation of initially formed carbinolamide intermediates [Pep-NH-CH(OH)-COX],wherein, while the former are shown to undergo hydrolysis to terminal amides [Pep-NH2], the oxalamides are found to be stable to hydrolysis. Ancillary noteworthy findings are those of peptide bond scission when contiguous Ser-Ser/Thr-Thr residues are present and the oxidative cleavage at C-terminal Tyr/Trp sites generating des amides. The oxidative methodology presented here is mild, simple, and practical and proceeds with chiral retention. The insensitivity of a large number of amino acid residues, such as Gly, Ala, Leu, Asn, Gln, Asp, Glu, Pro, Arg, Phe, Lys, Val, and Aib, and N-protecting groups, such as Boc, Z, and Bz, toward Ru(VIII) under the experimental conditions should make this methodology practical and useful. Sulfur-containing amino acids Cys and Met get oxidized to sulfones in the products.
Photaki, Iphigenia; Caranikas, Stephanos; Samouilidis, Ioannis, Journal of the Chemical Society. Perkin transactions I, 1980, p. 1965 - 1970