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 13C-NMR spectroscopy.
INTRODUCTION
Background of Study
The chemistry of phenoxazine and its derivatives have been of considerable interest over the years because of their important and impressive number of applications1, particularly as dyes and drugs2,3.
Phenoxazines are a pharmaceutically important class of tricyclic nitrogen-oxygen heterocycles4. They show tremendous pharmacological activities as anti-epileptic5,
Antitumour6,7, anticancer8, antituberculosis9, antibacterial10,11, anthelminthic12, spasmolytic, central nervous system (C.N.S) depressants,13,14 herbicides tranquilizers, sedatives15 and parasiticidal agents16.
Other applications of phenoxazine derivatives include their use as antioxidants17, biological stains18,19, acid-base indicators20, and barometric and stannometric redox indicators21-25.
Phenoxazine itself has been used as a stabilizer for the polymerization of vinylpyridines26, polyethylene and polystyrene27. Some of its derivatives were also reported as having radioprotective and antioxidative actions28.
Naphthoquinones are secondary metabolites largely found in plants, micro-organisms, and some animals29.
These compounds have been widely used as colorants for comestics30, fabrics31, foods, and for pharmacological activities such as antitumor, anti-inflammatory, antibacterial, antiviral, antiproliferative, antiparasitic, cytotoxic activities, and others32-34.
REFERENCES
Okoro, U.C; Okpunor, F and Ugwoke, R.O; (2009): The First Angular Triazaphenoxazinone the Related Diaza Analogue and Their Aniline Derivatives by Metal Catalyzed Coupling Reactions. International Journal Chem. 19(3) 107-117.
Gordon, M; Craig, P.N and Zirkle, C.L; (1964): Molecular Modification in the Development of Phenothiazine Drugs. American Chemical Society PP 140-147.
Boehringer, C.F; (1964): New Basic Derivatives of Phenoxazine. Chem. Abstr. 60, 14514.
Thomas, J.J.M; (1999): First Synthesis of Electronic Properties of Ring Alkynylated Phenothiazines. Tetrahedron Letters. 40, 6563-6566.
Brockmann, H; (1961): Chemistry of the Antinomycins in the Chemistry of Natural Product. International Union of Pure and Applied Chemistry Section of Organic Chemistry. Butterworths Publishers and Co. Ltd, London 405-421.
Shimamoto, T; Tomoda, A; Ishida, R and Ohyashiki, K; (2001): Antitumor Effects of a Novel Phenoxazine Derivative on Human Leukemia American Association for Cancer Research. 7, 704-708.
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