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Designing a New Ligand based on Pyridine for Immobilization of Gold Nanoparticles on Reduced Magnetic Graphene Oxide: A New Catalyst for the Reduction of Nitro Compounds and a Diastereoselective Construction of Functionalized Dihydro-Pyridazine based Spirooxindole Scaffold via C-3 Umpolung of Isatin N,N′-Cyclic Azomethine Imine

Siahpoosh, Ali | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51852 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Matloubi Moghadam, Firouz
  7. Abstract:
  8. In this work, a new catalyst based on gold nanoparticles immobilized on magnetic GO (graphene oxide) has been introduced. A new ligand based on pyridine has been used to the functionalization of GO to design robust heterogeneous catalyst for reduction in a short time using a low amount of the catalyst. The prepared catalyst was employed in the synthesis of aromatic amines using various types of nitroarnes in water. This catalyst is readily prepared from available starting materials and also is a reusable catalyst having very good stability to air and moisture. The proposed procedure applied here can conduct the reactions under milder reactions. Finally, due to total removal of the metal-based catalyst from the reaction media, the procedure can be applied in pharmaceutical processes. The designed catalyst was characterized by scanning electron microscopy (SEM), Fourier-transform infared spectroscopy (FT-IR), thermos gravimetric analysis (TGA), Energy-dispersive X-ray spectroscopy (EDS) and atomic absorption spectroscopy (AAS) analyses. The functionalized spiro[indoline-3,5'-pyrazolo[1,2-a]pyridazine]-7'-carbonitrile containing two contiguous chiral stereocenters were efficiently synthesized in satisfactory yield (up to 77% yield) and with excellent diastereoselectivity. This was performed by DABCO-catalyzed [3+3] annulation reactions of isatin N,N′cyclic azomethine imine 1,3-dipoles with knoevenagel intermediate in dichloromethane (DCM) as a solvent, and ambient temperature. It is an entirely new strategy to creation of one quaternary stereogenic center at 3-position of oxindole structure by abnormal Michael addition/N-cyclization unique approach through an azomethine imine 1,3-dipoles. Furthermore, the synthetic protocol, defined as GAP (Group-Assistant-Purification) chemistry process, can avoid traditional chromatography and crystallization. The X-ray crystallography data confirmed the structure of a typical product.
  9. Keywords:
  10. Magnetite ; Reduced Graphene Oxide ; Reduction (Chemistry) ; Pyridines ; Gold Nanoparticle ; Pyridazine-Based Organic Compounds ; Spirooxindole ; Knoevenagel Condensation ; Nitroarenes

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