Elham A. Al-Taifi,1Eman A. Thabet,2Etify A. Bakhite3* and Talaat I. El-Emary3
1Department of Chemistry, Faculty of Science, Sana’a University, Sana’a, Yemen
2Department of Chemistry, Faculty of Science, Taiz University, Taiz, Yemen
3Department of Chemistry, Faculty of Science, Assiut University, Assiut71516, Egypt
Received November, 2015; Accepted December, 2015
Abstract: 1-phenyl/(2-thienyl)-3-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-propen-1-ones (3a,b) were prepared. Reaction of 3b with hydroxyl amine, phenyl hydrazine or ethyl cyanoacetate gave the corresponding heterocyclic compounds 4, 5 and 6 respectively. Treatment compounds 3a,b with cyanothioacetaimde furnished 3-cyano-4-(1,3-diphenyl-1H-pyrazol-4-yl)-6-phenyl/(2-thienyl)pyridine-2(1H)-thiones (7a,b). Reaction of 7a,b with chloroacetamide, p-methylphenacyl chloride, ethyl chloroacetate, chloro-N-(aryl)acetamides gave S-substituted methylthiopyridines 8a-g. Upon treatment of compounds 8a-g with sodium ethoxide in boiling ethanol, they underwent intramolecular Thorpe-Zeigler cyclization giving 2-functionalized 3-amino-4-(1,3-diphenyl-1H-pyrazol-4-yl)-6-phenyl/(2-thienyl)thieno[2,3-b]pyridines (9a-g). Compounds 9a,c were subjected to some sequence reactions to produce new pyrazolylpyridothienopyrimidines 10a-c, 11a,b and 13-16.
Key words: 1,3-diphenylpyrazole, 3-cyanopyridine-2(1H)-thiones, pyrazolylthienopyridines, pyrazolylpyridothienopyrimidines