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Piperazine‐mediated tandem synthesis of bis(thieno[2,3‐ b ]pyridines): Versatile precursors for related fused [1,2,4]triazolo[4,3‐ a ]pyrimidines
Author(s) -
Sanad Sherif M. H.,
Mekky Ahmed E. M.
Publication year - 2020
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.4021
Subject(s) - chemistry , piperazine , triethylamine , moiety , reagent , yield (engineering) , pyridine , medicinal chemistry , tandem , benzoyl chloride , combinatorial chemistry , organic chemistry , materials science , metallurgy , composite material
In this study, we discuss the utility of bis(cyanoacetamides) as versatile precursors to the piperazine‐mediated synthesis of a wide spectrum of bis(thieno[2,3‐ b ]pyridine) derivatives, linked to aliphatic spacers via thioethers. The proposed tandem protocol involved the reaction of bis(cyanoacetamides) with two equivalents of the appropriate cinnamonitriles in dioxane in the presence of six equivalents of piperazine at reflux for 4 hours. Then, two equivalents of the appropriate halogen‐containing reagents were added and the reaction was heated at reflux for further 3 hours. The bis(thieno[2,3‐ b ]pyridines) were taken as a key intermediates to new bis(4‐oxopyrido[3′,2′:4,5]thieno[3,2‐ d ]pyrimidines). The above derivatives were reacted with the appropriate hydrazonyl chloride derivatives in dioxane in the presence of triethylamine to yield the corresponding bis([1,2,4]triazoles) with a related fused pyridothienopyrimidine moiety. The new structures were elucidated by IR, NMR spectral data, as well as elemental analyses.