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Synthesis of Heterocyclic Compounds via Domino Knoevenagel Hetero Diels–Alder Reaction on Thiocarbonyls and Investigation of Tandem Dinucleophilic Addition on Pyridinium Salts

Kiamehr, Mostafa | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 42890 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Matloubi Moghaddam, Firouz
  7. Abstract:
  8. In the first chapter, three efficient synthesis of novel polyheterocyclic indole and thiochromone-annulated thiopyranocoumarin derivatives are achieved via domino Knoevenagel hetero Diels–Alder reaction of O-acrylated and O-propargylated salicylaldehyde derivatives with indolin-2-thiones and 4-hydroxy dithiocoumarin. The domino Knoevenagel-hetero-Diels–Alder reactions are very efficient process that allows the formation of two or more rings at once, avoiding sequential chemical transformations. The products are formed in good-to-excellent yields with high regio- and stereoselectivity. The major advantage of this reaction is the ease of the work-up during which the products can be isolated without chromatography. This method also offers other advantages such as clean reactions, high yields of products and short reaction times, which make it a useful and attractive strategy for the synthesis of important heteropolycyclic compounds. Also, using H2O as a solvent has advantages, such as safety, environmentally friendly and low cost.
    We have also discovered a new and efficient synthesis of a great variety of bridged heterocyclic oxazocines and thiazocines via tandem 1,3-dinucleophilic addition of cyclic 1,3-diketones and thiooxindoles to diverse substituted pyridinium salts under basic condition. The reaction proceeds by regioselective attack of the carbon atom of dinucleophiles to pyridinium salts to form enamine intermediate with subsequent cyclization by intramolecular O/S-alkylation of nucleophiles. This method offers several advantages, such as good to excellent conversions, high regioselectivity, and experimentally simplicity starting from easily available starting materials that make it a useful and attractive strategy for the preparation of polycyclic tetrahydropyridines in a one-step operation
  9. Keywords:
  10. Knoevenagel Condensation ; Tandem Reaction ; Dinucleophile ; Hetero Diels-Alder ; Pyridiniume Salts ; Domino Reaction ; Tetrahydropyridine

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