SYNTHESES, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITIES OF ALKYNYLATED ANGULAR PHENOXAZINES AND ALKYNYLATED NAPHTHOQUINONES
ABSTRACT
The synthesis of ten new alkynylated derivatives of angular phenoxazine and alkynylated naphthoquinone was thoroughly investigated. The first intermediate, 6-chloro-5H-benzo[a]phenoxazin-5-one was obtained by the condensation of 2-aminophenol with 2,3-dichloro-1,4- naphthoquinone in the presence of anhydrous sodium tricarbonate (IV) . Thereafter, the intermediate and 2,3-dichloro-1,4-naphthoquinone were each suggested to Sonogashira cross–coupling reaction under copper-, amine-, and solvent free conditions at 80 oC with five different terminal alkynes using PdCL2(PPh3)2 and tetrabutylammonium trihydrate (TBAF.3H2O) as the catalyst and ligand respectively to afford the alkynylated angular phenoxazines and alkynylated naphthoquinone derivatives in good to excellent yield . Structures of synthesized compounds were confirmed with Uv-visible, Fourier Transform – Infrared (FT-IR), 1H-NMR and 1p3C-NMR spectroscopy. The synthesized compounds were screened against five (5) micro-organisms viz: Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli 1 and Escherichia coli 12 using agar well diffusion technique. The results showed significant improvement in antimicrobial activities compared with gentamycin and ampicillin (standard drugs).