Synthesis of Some Aryl Thienopyridine, Pyridothienopyrimidine, and Pyridothienotriazolopyrimidine Derivatives
El-Louh, A; Abdallah, SM; El-Sawi, EA
Synthesis of 2-thioxopyridine-3-carbonitriles 3a-d and
their reaction with chloroacetonitrile 4a or chloroacetamide 4b afforded pyridin-2-
ylthioacetonitriles 5a-d and pyridin-2-ylthioacetamides 6a-d, respectively, which on cyclization
gave the corresponding 3-aminothienopyridine derivatives 7a-d and 8a-d. Reaction of triethyl
orthoformate in acetic anhydride gave with 7a-d 3-ethoxymethylenethienopyridine derivatives 9a-d
which on their reaction with hydrazine hydrate yielded 3-amino-4-imino-3,4-
dihydropyridothienopyrimidine derivatives 10a-d. Reaction of triethyl orthoformate with 10a-d
produced pyridothienotriazolopyrimidine derivatives 11a-d, where Dimroth rearrangement yielded 4
-hydrazinopyridothienopyrimidine derivatives 12a-d. On the other hand reaction of 8a-d with
triethyl orthoformate in acetic anhydride gave pyridothienopyrimidine-4-one derivatives 13a-d,
which on their chlorination produced 4-chloropyridothienopyrimidine derivatives 14a-d, and
treatment with hydrazine hydrate authenticated 12a-d. Reaction of compounds 8a-d with nitrous
acid afforded 3,4-dihydropyridothienotriazin-4-ones 15a,b,d. Compounds 12a-d reacted with
benzaldehyde, diethylmalonate, and acetylacetone, to give 4-benzylidinehydrazinopyridopyrimidines
16a-d, ethyl 1,2,4-triazolopyridothienopyrimidin-3-ylacetates 17a-d, and 4-(3,5-dimethylpyrazolo)
pyridothienopyrimidines 18a-d, respectively. [Ali Khader El-Louh, Shadia Mahmoud Abdallah and
Emtithal Ahmed El-Sawi Synthesis of Some Aryl Thienopyridine, Pyridothienopyrimidine, and
Pyridothienotriazolopyrimidine Derivatives] Life Science Journal 2012;9(1):220-230]. (ISSN: 1097
-8135). http://www.lifesciencesite.com. 32