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  • Open access
  • 68 Reads
Tetrachlorosilane-A Versatile Reagent in Organic Synthesis
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A recent increased attention is witnessed to the use of tetrachlorosilane (TCS), a cheap industrial intermediate, as a versatile reagent in organic synthesis. For example, TCS was used as an effective dehydrating agent, trans-silylating reagent and as a starting substrate for in situ preparation of other useful stoichiometric reagents in synthetic organic chemistry. Of these reagents TCS-NaI (Iodotrichlorosilane, ITCS), TCS-NaN3 (azidochlorosilanes) and TCS in combination with ZnCl2, Zn, KCN, Na2S and others. Some selected synthetic applications of TCS as dehydrating agent as well as one of its based "in situ" reagents (TCS-NaN3) are briefly highlighted herein.
  • Open access
  • 70 Reads
Synthesis of Enantiopure Methyl (1S,2S,3R,4S,5R)-2-Amino-3,4,5-trihydroxycyclopentanecarboxylate
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The first total synthesis of enantiopure methyl (1S,2S,3R,4S,5R)-2-amino-3,4,5-trihydroxycyclopentanecarboxylate was carried out according to our recent novel strategy for the transformation of nitrohexofuranoses into cyclopentylamines, which is based on an intramolecular cyclization leading to 2-oxabicyclo[2.2.1]heptane derivatives. Differences in reactivity for this key step were rationallized by using molecular mechanism based calculations.
  • Open access
  • 50 Reads
Synthesis of New 2-(3-Hydroxy-4-oxo-4Hnaphthalenylidene) acetonitriles in Aqueous Solvent
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We have prepared a serie of new naphthoquinomethanes: [2-(3-hydroxy-4-oxo-4H-naphthalen-1-ylidene) acetonitriles] by the cascade Michael-elimination reaction of sodium 1, 2-naphthoquinone-4-sulfonate with substituted acetonitriles in basic ethanol-water.
  • Open access
  • 39 Reads
Benzylic Newman-Kwart rearrangement triggered by Phosphanes
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A Staudinger imination reaction of tertiary phosphanes with O-(azidobenzyl)thioncarbamates, bearing the azido function at ortho or para position, promotes a rare benzylic Newman-Kwart rearrangement.
  • Open access
  • 72 Reads
Convenient synthesis of some methyl-N-[2-(6-oxo-3-p-tolyl-5,6-dihydro-4H-pyridazin-1-yl)-acetamide]alkanoates
An efficient one-pot synthesis of methyl-N-[2-(6-oxo-3-p-tolyl-5,6-dihydro-4Hpyridazin-1-yl)-acetamide]alkanoates 5a-j and dipeptides 8a-f was successfully realized starting from amino acid esters 4 and azides 3, 7, respectively. The hydrazide 6a was further reacted with selected aldehydes to give the corresponding hydrazones 9a-c.
  • Open access
  • 41 Reads
Ultrasonic method for the preparation of organic nanoparticles of porphyrin
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We report the synthesis and optical properties of organic porphyrin nanoparticles with narrow size distribution and well dispersibility. Nanoparticles were produced by a combination of the reprecipitation and sonication method and termed the “ultrasonic method”. The TPClPP nanoparticles were stable in solution without precipitation for at l ast 30 days. No self-aggregation of the constituent porphyrin chromophores was confirmed. The TPClPP nanoparticles exhibited interesting optical properties; a large bathochromic shift in the absorption spectra.
  • Open access
  • 110 Reads
1,3-Dipolar Cycloaddition of 3-Oxidopyrazinium to Methyl Acrylate: An Experimental and Computational Investigation
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1,3-Dipolar cycloaddition reaction between 3-oxidopyrazinium and methyl acrylate has been studied both experimentally and theoretically. Structures of the obtained cycloadducts, exo and endo isomers, were characterised based on spectral data namely IR, 1H and 13C NMR. These reactions can be interpreted in terms of the classical 1,3-dipolar cycloaddition reaction of 3-oxidopyridinium. Moreover the observed cycloaddition reaction has been investigated theoretically by means of the Hartree-Fock method using 6-31G as the basis sets in the gas phase in order to have more insight into their reaction profiles. All the geometries on the reaction paths have been optimised and the transition state structures have been ascertained by frequency analysis. Since the synthesis has been carried out in acetonitrile, the optimised structures have been used for single point computationin this solvent using the density functional method with B3LYP as the functional. The computations have allowed the determination of the activat on energies and enthalpy changes of the reactions. These have been used for the interpretation of kinetic and thermodynamic stabilities. It is generally found that the addition reactions have lower activation energy and enthalpy changes in acetonitrile compared to the gas phase.
  • Open access
  • 45 Reads
Parallel Kinetic Resolution of 1-Phenylethanol Using Quasi-Enantiomeric Active Esters
Parallel Kinetic Resolutions (PKRs) involves the parallel separation of enantiomers under kinetic control. We have recently reported the parallel kinetic resolution of racemic oxazolidinone (rac)-4 using a combination of quasienantiomeric active esters (S)-5 and (R)-6. These processes proceeded efficiently to give separable diastereoisomeric adducts (S,R)-syn-7 and (R,S)-syn-8 in good yields with excellent levels of stereocontrol (>90% d.e.).