Abstract
A series of 2,6‐bis(substituted thiazolopyrimi‐dinyl) pyridine (2a,b) and corresponding Schiff′s bases (3a–j) were synthesized from 2,6‐bis‐(3‐amino‐2‐methyl‐4‐oxo‐9‐substituted‐3,4‐dihydropyrido‐[30,20 : 4,5]‐thieno[3,2‐d]pyrimidin‐7‐yl)pyridines (1a,b) as starting materials. The compounds 1a,b were reacted with 2,3,4,5‐tetrachlorophthalic anhydride in glacial acetic acid to give the corresponding bis‐imides (2a,b). But they are treated with aromatic aldehydes in refluxing ethanol to afford the Schiff’s base derivatives (3a–j). The antimicrobial screening showed that many of these newly synthesized compounds had good antimicrobial activities comparable to streptomycin and fusidic acid as positive controls. The detailed synthesis, spectroscopic data, and antimicrobial activities of the synthesized compounds were reported.
Highlights
Antimicrobial agents reduce or completely block the growth and multiplication of bacteria and are helpful in the treatment of various infectious diseases like meningitis, malaria, tuberculosis, pneumonia, AIDS, and so forth. e compounds with the structure of –C=N- are known as Schiff bases, which are usually synthesized from the condensation of primary amines and active carbonyl groups
Chemistry. e synthetic route is given in Scheme 1. 2,6Bis(3-amino-2-methyl-4-oxo-9-substituted-3,4-dihydropyrido [30,20:4,5]thieno [3,2-d]-pyrimidin-7-yl)pyridine (1a,b) was synthesized as starting material according to the literature procedure [19]. e reaction of N-amino pyrimidine derivatives 1a,b with 2,3,4,5-tetrachlorophthalic anhydride in glacial acetic acid afforded the corresponding bis-imide derivatives 2a,b, respectively
All the synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and mass spectrometer techniques. e antimicrobial activities of the compounds 2a,b and 3a–j were evaluated against three bacterial and four fungal strains
Summary
Antimicrobial agents reduce or completely block the growth and multiplication of bacteria and are helpful in the treatment of various infectious diseases like meningitis, malaria, tuberculosis, pneumonia, AIDS, and so forth. e compounds with the structure of –C=N- (azomethine group) are known as Schiff bases, which are usually synthesized from the condensation of primary amines and active carbonyl groups. E compounds with the structure of –C=N- (azomethine group) are known as Schiff bases, which are usually synthesized from the condensation of primary amines and active carbonyl groups. Schiff bases derived from aromatic amines and aromatic aldehydes have a wide variety of applications in many elds, for example, biological, inorganic, and analytical chemistry [1–4]. In our previous work, Schiff bases show biological properties including antibacterial, antifungal antitumor, analgesic, and anti-in ammatory activities [9–18]. In view of these observations and in continuation of our previous work in heterocyclic chemistry, we synthesized some new heterocyclic imide and Schiff base derivatives containing pyridine, thiophene, and pyrimidine rings for the evaluation of antimicrobial activity compared to streptomycin and fusidic acid as positive controls
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