Pyridine-based heterocycles. Synthesis of new pyrido [4',3':4,5]thieno[2,3-d]pyrimidines and related heterocycles
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Updated: Jun 13, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Hussein El-Kashef1, Abdel-Rahman Farghaly, Ahmed Al-Hazmi
1Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt. elkashef@aun.edu.eg
Abstract:
The synthesis of the title compounds was achieved using ethyl 2-amino-6-methyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate (1) as starting material. The reaction of the amino ester 1 with phenylisothiocyanate in boiling ethanol afforded the thiourea derivative 5. The cyclization reactions of 5 under different reaction conditions led to different pyridothienopyrimidine derivatives. Other reactions of the latter derivatives leading to pyrido[4',3':4,5]thieno[2,3-d]triazolo[1,5-a]pyrimidines are also presented.
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