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Wednesday 26 December 2012

Iron-Catalyzed Synthesis of 2-Arylbenzo[b]furans




Iron-Catalyzed Synthesis of 2-Arylbenzo[b]furans

Synthetic Communications

Volume 43, Issue 6, 2013


Jianguo YangGuodong Shen & Dingben Chen
pages 837-847

DOI:10.1080/00397911.2011.610550
http://www.tandfonline.com/doi/abs/10.1080/00397911.2011.610550
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Abstract

An iron-catalyzed procedure was employed to achieve both the Sonogashira cross-coupling and intramolecular o-arylation of o-iodophenols and aryl acetylenes/1-substituted-2-trimethylsilyl acetylenes. A variety of 2-arylbenzo[b]furans were synthesized in moderate to good yields under the catalysis of 5% FeCl3 and 10% 1,10-phenanthroline.

Monday 3 December 2012

Sodium dodecyl sulfate in water: greener approach for the synthesis of quinoxaline derivatives





A simple energy efficient one step SDS catalysed 0.03% greener method for the synthesis of quinoxaline der using water as solvent is described

A mild and efficient synthetic method has been developed for the preparation of biologically important quinoxalines in excellent yield from relatively safe precursor α-bromoketones and 1,2-diamines using catalytic amount of micellar sodium dodecyl sulfate in water at ambient temperature. The method is also found effective for the introduction of quinoxaline moiety into the ring A of pentacyclic triterpenoid, friedelin. Ambient reaction conditions, renewable catalytic condition, inherently safer chemistry, excellent product yields, and water as a reaction medium display both economic and environmental advantages.

General procedure for quinoxalines

In a typical experimental procedure, o-phenlylenediamine (1 mmol) and α-bromoketone (1 mmol) in 1:1 molar ratios was taken in a 50 ml round bottom flask. To this water (3 ml) and 10 mg (0.03 mol%) SDS was admixed. The reaction mixture was then allowed to stir with magnetic spinning bar at room temperature. After the completion of the reaction (checked by TLC), the residue was filtered, washed with water, dried and finally recrystallized from methanol. The desired pure product was characterized by spectral (IR, 1H- and 13C-NMR) data and compared to those reported in literature.

Green Chemistry Letters and Reviews

http://www.tandfonline.com/doi/full/10.1080/17518253.2012.703245

DOI:
10.1080/17518253.2012.703245
Pranab Ghosh & Amitava Mandal
 Department of Chemistry, University of North Bengal, Darjeeling, West Bengal, 734 013, India

Sodium dodecyl sulfate in water: greener approach for the synthesis of quinoxaline derivatives

Quinoxalines are ubiquitous heterocyclic units in pharmaceuticals and bioactive natural products 1–4. They are used as pharmaceuticals and antibiotics such as echinomycin, levomycin, and actinoleutin which are known to inhibit the growth of Gram-positive bacteria and are also active against various transplantable tumors 1–3. Antitumoral properties of quinoxaline compounds have also been investigated


Saturday 24 November 2012

Continuous Flow Synthesis of Organic Electronic Materials – Case Studies in Methodology Translation and Scale-up



 Continuous Flow Synthesis of Organic Electronic Materials – Case Studies in Methodology Translation and Scale-up
 Helga Seyler , Wallace W. H. Wong et al

Australian Journal of Chemistry - http://dx.doi.org/10.1071/CH12406
Submitted: 1 September 2012  Accepted: 3 October 2012   Published online: 19 November 2012
 
Continuous flow chemistry was applied for the derivatization of alkylthiophene building blocks. The advantages of reaction automation and scale-up were demonstrated for selective lithiation-borylation and Knoevenagel condensation of thiophene derivatives. These synthetic approaches allow facile and rapid access to monomer and dyes for organic electronic applications.
read more at
 http://www.publish.csiro.au/paper/CH12406.htm     copy paste link

Wednesday 21 November 2012

Reduction of Sulfonylimines with Raney Nickel




Reduction of Sulfonylimines with Raney Nickel

José Luis García Ruano, José A. Fernández-Salas, M. Carmen Maestro & Alejandro Parra
pages 198-207

  • DOI:10.1080/00397911.2011.594974
  • http://www.tandfonline.com/doi/abs/10.1080/00397911.2011.594974   copy paste link

Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,Volume 43, Issue 2, 2013  advance article                   

Raney-Ni/EtOH reduction of different N-sulfonylimines provides a new entry for synthesizing sulfonamides in good yields under mild conditions. This protocol, which does not require additional hydrogen, constitutes a cheap, safe, and easy-to-handle alternative procedure to prepare α-branched sulfonamides.

Synthesis of Enantiomerically Enriched α-Bromonitriles from Amino Acids



Synthesis of Enantiomerically Enriched α-Bromonitriles from Amino Acids

Najeh Tka, Jamil Kraïem & Béchir Ben Hassine
pages 735-743, DOI:10.1080/00397911.2011.608142

http://www.tandfonline.com/doi/abs/10.1080/00397911.2011.608142
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Two methods were investigated for the preparation of six chiral α-bromonitriles with different optic purities. The nitrous deamination of amino acids gives α-bromoacids, which react with chlorosulfonyl isocyanate followed by triethylamine to afford α-bromonitriles with moderate enantiomeric excess. However, the dehydration of corresponding α-bromoamids using thionyl chloride gives α-bromonitriles with good enantiomeric excess up to 94%. The use of phosphoryl chloride instead of thionyl chloride results in more than 30% racemization as determined by high-performance liquid chromatograpic analysis.

Sunday 18 November 2012

Synthesis of Quinolines Using Nano-Flake ZnO as a New Catalyst under Solvent-Free Conditions

J. Iran. Chem. Soc., Vol. 8, No. Suppl., February 2011, pp. S119-S128.
http://www.ics-ir.org/jics/archive/v8/S1/Articles/pdf/JICS-8-S1-Article-13.pdf
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Synthesis of Quinolines Using Nano-Flake ZnO as a New Catalyst under Solvent-Free Conditions


M. Hosseini-Sarvari, Department of Chemistry, College of Science, Shiraz University, Shiraz, 71454, Iran

     Catalytic activity of nano-flake ZnO for synthesis of quinoline derivatives and their related polyheterocycles under solvent-free conditions has been studied. Nano-flake ZnO has been successfully synthesized by conventional heating of a solution approach using ZnOAc.2H2O and Urea. This method is simple, cost-effective, and environmentally benign and the catalyst can be reused for several times.






Thursday 15 November 2012

Diversity Oriented Syntheses of Conventional Heterocycles by Smart Multi Component Reactions (MCRs) of the Last Decade



abstract graphic


Molecules 2012, 17(1), 1074-1102; doi:10.3390/molecules17011074
http://www.mdpi.com/1420-3049/17/1/1074   copy paste on browser

 A collection of smart multicomponent reactions (MCRs) with continuative post condensation cyclizations (PCCs) is presented to construct conventional three- to seven-membered heterocyclic compounds in diversity oriented syntheses (DOS). These will provide a high degree of applying economical and ecological advantages as well as of practicability. Water, ionic liquids, and solvent-less syntheses as well as use of various forms of energy as microwave and ultrasonic irradiation are examined and discussed.