Hypervalent iodine(V) mediated mild and convenient synthesis of substituted 2-amino-1,3,4-oxadiazoles

A simple protocol for the synthesis of 2-amino-1,3,4-oxadiazoles starting from the corresponding acylhydrazides by cyclodesulfurization of intermediate acylthiosemicarbazides mediated by o-iodoxybenzoic acid in good yields has been described. The protocol is mild with wide substrate scope, and thus a range of 2-amino-1,3,4-oxadiazoles have been prepared. © 2012 Elsevier Ltd. All rights reserved

Direct synthesis of Fmoc protected amino acid hydroxamates from acid chlorides mediated by magnesium oxide

The synthesis of Fmoc protected amino acid hydroxamates using Fmoc-amino acid chlorides and magnesium oxide is described. The method is simple and efficient, results in complete conversion, and gives good yields and satisfactory purity. © 2003 Elsevier Science Ltd. All rights reserved

Density functional theoretical studies on photoswitching and charge migration dynamics of thio and selenoureidopeptides

Density functional theoretical calculations have been performed to investigate the changes in electronic structure at ground and excited states of ureidopeptides on substitution with higher chalcogens like sulphur and selenium for oxygen. This replacement results in a reduced preference towards the intramolecular hydrogen bonding interaction, thus linear conformers are found to be stable at both states. Nevertheless, conformational switching observed during this process is mainly due to n to �* transition that leads to the dihedral angle � change from trans to cis with a rotational barrier of 10 to 17 kcal mol-1. The computed barrier is lesser than that reported for oxopeptides (20 kcal mol-1). And, the hole migration dynamics after immediate ionization illustrates that the hole originated at ureido end evolves in time (2�4 fs) while the hole generated at the carboxylate end will not evolve as reported for ureidopeptides. The usage of these candidates as photoswitches has also been explored. Copyright © 2017 John Wiley & Sons, Ltd

ChemInform Abstract: Synthesis of Urea Tethered Glycosylated Amino Acids and Glycopeptides Mediated by DPPA Employing Nα‐Fmoc‐Asp/Glu‐5‐oxazolidinones

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

Facile and One-pot Synthesis of Nα-fmoc/bsmoc/boc/z-protected Ureidopeptides and Peptidyl Ureas Employing Diphenylphosphoryl Azide [DPPA]

Diphenylphosphoryl azide (DPPA) mediated one-pot synthesis of Nα-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas as well as phenyl/succinimidyl (Nα-urethane protected) methyl carbamates starting from Nα-protected amino acids is reported. The formation of an azide, its rearrangement and coupling with an amino component is accomplished in a sequence of one-pot operations. The protocol has incorporated urea linkages in a sterically hindered peptide

A facile synthesis of N-Z/Boc-protected 1,3,4-oxadiazole-based peptidomimetics employing peptidyl thiosemicarbazides

Synthesis of 1,3,4-oxadiazole containing peptidomimetics is described by a p-TsCl/pyridine-mediated cyclization of the corresponding dipeptidyl thiosemicarbazides, which are readily prepared by coupling N-protected amino acid hydrazides with amino acid-derived isothiocyanato esters. Further, the protocol has also been extended for the synthesis of orthogonally protected 1,3,4-oxadiazole tethered mimetics as well. The synthetic route is simple and mild conditions are used so that the chirality of the starting amino acids is retained. © 2010 Elsevier Ltd. All rights reserved

ChemInform Abstract: A Facile Synthesis of N‐Z/Boc‐Protected 1,3,4‐Oxadiazole‐Based Peptidomimetics Employing Peptidyl Thiosemicarbazides.

A convenient protocol is presented for the cyclization of dipeptidyl thiosemicarbazides (III)

Ultrasound accelerated conversion of Nα-urethane protected peptide esters to their thiopeptides using P2S5

A fast and efficient synthesis of Nα-protected thiopeptide esters from the corresponding peptide esters using P2S5 as thionating agent assisted by ultrasonication has been described. The conversion of peptide bond into thioamide was complete in 20-40 min at rt. The reaction was accomplished without using any base. The products isolated were characterized using 1H NMR, 13C NMR and mass spectroscopy. © 2008 Elsevier B.V. All rights reserved

A simple and greener approach for the synthesis of PVC supported Pd (0): Application to Heck and Sonogashira reactions in water

Preparation of PVC-supported Pd nanoparticles through the reduction of PdCl2 by a non-toxic and eco-friendly route, employing sodium formate and NaOH in ethanol-water system has been described. The prepared PVC supported Pd nanoparticles were employed as catalyst in the cross coupling reactions, that is, Heck and Sonogashira reactions in water medium to afford the respective products in good to excellent yields. © 2014 Elsevier Ltd. All rights reserved

Microwave assisted Wolff rearrangement: A facile method for the synthesis of Fmoc-β-amino acids

The Wolff rearrangement of α-diazoketones, derived from Fmoc-α-amino acids, under no base conditions on exposure to microwave irradiation for 40 to 60 sec to Fmoc-β-amino acids with retention of configuration in good yield (91-95%) is described