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

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

Synthesis of novel glycopeptidomimetics via Nβ-protected- amino alkyl isonitrile based Ugi 4C reaction

The Ugi-4C reaction employing Nβ-protected-amino alkyl isonitrile, amino acid ester, aldehyde, and glycosyl acid has resulted in novel glycosylated peptidomimetics. The extension of MCR products for the synthesis of N,Nâ²-orthogonally protected glycosylated peptidomimetics has also been demonstrated. © 2013 Elsevier Ltd. All rights reserved

Synthesis of chiral Nβ-protected amino diselenides from the corresponding amino alkyl iodides using NaBH2Se3 as a selenating reagent and their conversion to seleninic acids

A convenient approach has been presented for the synthesis of Nβ-protected amino diselenides from the corresponding amino alkyl iodides using in situ generated NaBH2Se3 as an efficient selenating reagent. All the diselenides are obtained in good yields under very mild conditions, short duration times and the protocol is free from racemization. The methodology has been effectively extended to the synthesis of N-protected L-selenocystine methyl ester. Clean oxidation of Nβ-protected amino diselenides to Nβ-protected amino seleninic acids using 35% aqueous H2O2 has also been accomplished. The present protocol is compatible with all the common urethane protecting groups. Graphical abstract: Synthesis of chiral Nβ-protected amino diselenides from the corresponding amino alkyl iodides using NaBH2Se3 as a selenating reagent and their conversion to seleninic acid

Design and Synthesis of a Novel N-(1H-tetrazol-5-yl)methyl Cyclic Peptoid Using Nosyl-protected N-(1-trityl-1H-tetrazol-5-yl)methyl Substituted Glycine

Abstract: A solid phase synthesis of a cyclic peptoid bearing (1H-tetrazol-5-yl)methyl as N-substituent has been developed employing the monomer approach. The requisite monomeric Nosyl-protected N-(1-trityl-1H-tetrazol-5-yl)methyl substituted glycine was accessed by a convenient synthesis involving Click reaction of Nosyl-protected N-(cyanomethyl)glycine methyl ester and sodium azide as a key step. This building block was then employed in the solid phase synthesis of a tetramer peptoid. The linear tetramer was subjected to macrocyclization using PyBOP to obtain a cyclic peptoid with (1H-tetrazol-5-yl)methyl pendants in good yield. © 2017, Springer Science+Business Media New York

Conjugation of Au Nanoparticles with Chlorambucil for Improved Anticancer Activity

Gold nanoparticles (AuNPs) of 30–40 nm in size has been prepared using A. hirsutus leaves extract as reducing agent for Au3+ ions under microwave irradiation from 60 to 360 s. These biocapped AuNPs were effectively conjugated with activated folic acid (FA, receptor) and chlorambucil (CHL, anticancer drug) molecules. The formation of AuNPs–FA–CHL was confirmed from different characterization techniques such as XRD, UV–Visible spectra, FT-IR and TEM images. The anticancer activity of these bioconjugated AuNPs was tested against human cancer cell lines (HeLa, RKO and A549) in comparison with normal epithelial cells (Vero). Unlike AuNPs and CHL alone, AuNPs–FA–CHL showed high toxicity towards human cancer cells by significantly decreasing the percentage viability of cells. Furthermore, the amount of drug released was found to be maximum at an ideal tumor environment pH 5.3. Keyword

“ Thioureidopeptide”: Novel Synthon for the Synthesis of N, N′, N″-Trisubstituted Guanidinopeptide Mimics

The synthesis of N α-protected N,N′,N″-trisubstituted guanidinopeptide mimic molecules suitably decorated in peptide backbone has been delineated in one pot employing HgCl2 as a desulphurizing agent. Chiral N α -protected thioureidopeptide esters were employed as synthons for the synthesis of title molecules. The protocol is simple and the reaction conditions employed were mild, amenable to the amino acid chemistry

Lifetime distributions in the methods of non-equilibrium statistical operator and superstatistics

A family of non-equilibrium statistical operators is introduced which differ by the system age distribution over which the quasi-equilibrium (relevant) distribution is averaged. To describe the nonequilibrium states of a system we introduce a new thermodynamic parameter - the lifetime of a system. Superstatistics, introduced in works of Beck and Cohen [Physica A \textbf{322}, (2003), 267] as fluctuating quantities of intensive thermodynamical parameters, are obtained from the statistical distribution of lifetime (random time to the system degeneracy) considered as a thermodynamical parameter. It is suggested to set the mixing distribution of the fluctuating parameter in the superstatistics theory in the form of the piecewise continuous functions. The distribution of lifetime in such systems has different form on the different stages of evolution of the system. The account of the past stages of the evolution of a system can have a substantial impact on the non-equilibrium behaviour of the system in a present time moment.Comment: 18 page