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An efficient functionalization of tyrosine residues in phenolic regions is achieved under metal-free conditions. The strategy involves the conversion of a tyrosine residue to 4-amino phenylalanine or 4-amino-3-methoxy phenylalanine in short peptides through a controlled oxidative dearomatization. This transformation is achieved in one pot with good yields and excellent regioselectivity. Consequently, the self-assembly of the peptide compounds has been studied at the nanoscopic level before and after functionalization. The results suggest that the peptide derivatives comprising amide groups promote intermolecular H-bonding interactions and the difference in -OH and -NH 2 functional groups is found to be responsible for the morphological changes. Morphological transitions from 1D nanowires to 2D nanosheets were observed during functional group modification.

[Display omitted] An efficient and fast synthesis of dalargin, a potent synthetic opioid peptide was achieved on gram scale within 2 days, with 98% HPLC purity in solid phase peptide synthesis. Benzoisothiazolone was used as reusable coupling reagent in the present peptide synthesis and was recycled up to 90%. The expensive conventional coupling reagents in the peptide synthesis were replaced by a recyclable and fast coupling reagent there by improving the economic and safety factors of peptide synthesis. [ABSTRACT FROM AUTHOR]

We report herein a scalable synthesis of linear heptapeptide side chain of the depsipeptide natural product teixobactin through solution phase. The synthesis of heptapeptide was achieved through an efficient coupling of suitably protected tripeptide and tetrapeptide comprising of three d -amino acids and four usual l -amino acid subunits. [ABSTRACT FROM AUTHOR]

Strained unusual amino acid derived tetrapeptides were synthesized as mimics of GLYX-13, a clinical candidate for neuroprotective and anti-depressant properties, were studied. The synthesized compounds were screened for neurite growth and anti-depressant properties in vitro and in vivo respectively comparing with the parent GLYX-13 compound. Neurite growth property was assessed by neurite length and anti-depressant property by percentage of immobility in forced swim test, a behavioural assay. Mechanistic insights about protein–ligand interactions were obtained using molecular docking study. Based on the in vitro and in vivo screening data and molecular docking study, a new analogue of GLYX-13, Compound 11a has been found to be as good as the parent compound in all respects. [ABSTRACT FROM AUTHOR]

[Display omitted] An efficient strategy to afford pyrrolidine derivatised peptides through late-stage modification of tyrosine-containing short peptides is presented. The metal-free dearomative strategy showed good site selectivity and specificity to afford unnatural amino acid scaffolds under metal-free conditions and involved three-component coupling. [ABSTRACT FROM AUTHOR]