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Updated: Sep 26, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
A highly efficient photochemical bromination as a new method for preparation of mono, bis and fused pyrazole
Saleh A Ahmed1, Ibrahim M A Awad, Aboel-Magd A Abdel-Wahab
1Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt. a.saleh@lcoo.uni-bordeaux.fr
Abstract:
N-Bromosuccinimide (NBS) was found to afford photochemical bromination of N-substituted 3-methyl-2-pyrazolin-5-one in chloroform solution. The nature of the products formed was found to be highly dependent on the photolysis time and on the type of N-substituted 3-methyl-2-pyrazolin-5-one. The reaction of substituted 2-pyrazolin-5-ones with NBS in the absence of light yielded in all cases a mixture of N-substituted 3-methyl-4-bromo- (and -4,4-dibromo-) 2-pyrazolin-5-ones. The mechanism of photobromination was illustrated. Separation of all of the products was achieved using column chromatography. The chemical structure of all of the products was assigned by elemental analysis, IR, 1H NMR and GC-MS measurements.
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