H. P. Hemantha

Poly(vinyl)chloride supported palladium nanoparticles: catalyst for rapid hydrogenation reactions

Palladium nanoparticles supported over poly(vinyl)chloride matrix (PVC-Pd(0)) are prepared through an efficient and inexpensive protocol. The catalyst has been characterized by XRD, SEM and TEM and its utility for the reduction of a range of functional groups as well as for the removal of some common protecting groups employed in peptide chemistry is demonstrated.

Isoselenocyanates derived from amino acid esters: An expedient synthesis and application to the assembly of selenoureidopeptidomimetics, unsymmetrical Selenoureas and selenohydantoins

An important class of organoselenium compounds‐α‐isoselenocyanato esters 4 hasbeen prepared by a reaction of α‐isocyano esters with elemental selenium powder. The reaction issimple, rapid and all the isoselenocyanates havebeen isolated as stable ones after chromatographic purification. These hitherto unreported classes of molecules would be useful building blocks for the preparation of variety of selenium containing peptidomimetics. In this study, the utility of the title molecules in the preparation of selenoureidopeptidomimetics 6, unsymmetrical selenoureas 8 and selenohydantoins 10 isdemonstrated. Copyright

A Facile Synthesis of C-terminal Neoglycopeptides: Incorporation of Urea Moiety between Sugars and Peptides Employing Curtius Rearrangement

Incorporation of urea moiety in the synthesis of C-terminal neoglycopeptides has been demonstrated through the reaction between suitably protected glycosylamine and Fmoc-peptidyl isocyanates or carbamates. Curtius rearrangement has been made use off for the conversion of peptidyl acid azides in to corresponding isocyanates. The resulting C-terminal neoglycopeptidylureas have been isolated as stable solids which are fully characterized by 1H NMR and mass spectroscopy.

Click Chemistry Aided Synthesis of 1,4-Substituted 1,2,3-Triazole Based N-Fmoc Protected -Amino Acids: Isolation, Characterization and Synthesis of Novel Triazole Based Unnatural Amino Acids

A new class of 1,4-substituted 1,2,3-triazole-based unnatural amino acids is demonstrated by employing click reaction between N-Fmoc amino alkyl azides and propiolic acid. The resulting unnatural amino acids were isolated and then subjected to Fmoc deprotection to isolate 1,2,3-triazole based amino acids as stable solids. These new class of molecules were also used for chain extension from both N- and C-terminals to synthesize dipeptidomimetics bearing 1,2,3-triazole moiety in the backbone.

Synthesis of Hybrid Peptidomimetics and Neoglycoconjugates Employing Click Protocol: Dual Utility of Poc-Group for Inserting Carbamate-Triazole Units into Peptide Backbone

Synthesis of new types of peptidomimetics and glycosylated amino acids possessing 1,2,3-triazole and carbamate moieties is described. Poc-protected amino acid esters/1-amino sugars were subjected to Cu(I) catalyzed [2+3]cycloaddition with desired azides under click protocol to obtain novel peptide and carbohydrate mimetics. The reaction is rapid, efficient and all the products are isolated in good yield and excellent purity.

Efficient Synthesis of N-Fmoc-Aminoalkoxy Pentafluorophenyl Carbonates: Application for the Synthesis of Oligopeptidyl Carbamates

Abstract N-Fmoc-β-Aminoalkoxy pentafluorophenyl carbonates have been synthesized through the reaction of N-Fmoc-β-aminoalkoxy carbonyl chloride with pentafluorophenol. The reaction was clean and high yielding, and the products have been fully characterized using infrared, NMR, and mass spectroscopy. Their utility as efficient building blocks for the preparation of N-Fmoc-oligopeptidyl carbamate esters and acids has been demonstrated. The method exemplifies a simple protocol for the efficient preparation of oligopeptidyl carbamates in solution phase.

Simple Preparation of N-Protected Chiral β-Amino Alkyl Thiols from Corresponding Iodides Employing Sodium Trithiocarbonate

Abstract A simple protocol for the preparation of N-protected amino alkyl thiols is reported that employs a reaction of sodium trithiocarbonate (Na2CS3) with N-protected amino alkyl iodides. Na2CS3 is easy to prepare and the protocol circumvents the use of strong bases and multiple steps. All the thiol compounds made were obtained as enantiopure samples and were characterized employing NMR and mass spectrometry. GRAPHICAL ABSTRACT

Quinoline-Thioureidopeptides: A New Approach for the Synthesis of Quinoline-Isothiocyanate and Their Peptide Linkage

We present an efficient synthetic route for quinoline condensed thioureidopeptidyl esters from corresponding isothiocyanate and amino acid esters. The utility of quinoline isothiocyanate as major building block for desired thioureidopeptides of quinoline interests, with good yield with excellent purity. All the new compounds are well characterized by IR, 1H NMR, mass and elemental analysis data.

Cyanogen Bromide as DehydrosulfurizingAgent for the Synthesis of Nβ-Fmoc-AminoAlkyl Isonitriles from Nβ-Fmoc-AminoAlkyl Thioformamides

Synthetically useful NI²-Fmoc amino alkyl isonitriles are prepared conveniently from NI²-Fmoc amino alkyl thioformamides via a cyanogen bromide mediated dehydrosulfurization. The reaction is fast, clean, and yields are good. © Georg Thieme Verlag Stuttgart - New York.