Microwave-assisted synthesis of 4 '-azaflavones and their N-alkyl derivatives with biological activities

YAŞAR A., Akpinar K., Burnaz N. A., KÜÇÜK M., Karaoglu Ş., DOĞAN N., ...More

CHEMISTRY & BIODIVERSITY, vol.5, no.5, pp.830-838, 2008 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 5 Issue: 5
  • Publication Date: 2008
  • Doi Number: 10.1002/cbdv.200890078
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.830-838
  • Recep Tayyip Erdoğan University Affiliated: Yes


4'-Azaflavone (= 2-(pyridin-4-yl)-4H-1-benzopyran-4-one; 4) and 3-[(pyridin-4-yl)methyll-4'-aza-flavone (5) were synthesized by a simple environmentally friendly microwave-assisted one-pot method through the cyclization of 3-hydroxy-1-(2-hydroxyphenyl)-3-(pyridin-4-yl)propan-1-one (1), (E)-2'-hydroxy-4-azachalcone (2; chalcone = 1,3-diphenyl prop-2-en-1-one), and 2'-hydroxy-2-[(hydroxy)(pyridin-4-yl)methyl]-4"-azachalcone (3) under solventless conditions using silica-supported NaHSO4, followed by treatment with base. In addition, N-alkyl-substituted 4'-azaflavonium bromides 6 and 7 were prepared from compounds 4 and 5, respectively. The antimicrobial and antioxidant activities of compounds 1-7 were tested. The N-alkyl-substituted 4'-azatlavonium bromides 6 and 7 showed high antimicrobial activity against the Gram-positive bacteria and the fungus tested, with MIC values close to those of reference antimicrobials ampicilline and fluconazole. The alkylated compounds 6 and 7 also showed a good antioxidant character in the two antioxidant methods, DPPH (=1,1-diphenyl-2-picrylhydrazyl) radical-scavenging and ferric reducing/antioxidant power (FRAP) tests.