Organic Chemistry

Ten new heterocyclic moiety containing Schiff bases have been synthesized by the condensation of 4,5-diazafluoren-9-one with substituted amines by using SnCl₂ as a catalyst under solvent free condition. The Schiff bases were obtained in good yields and easy to isolate. Some synthesized products were characterized by IR, NMR and MASS and also tested for antibacterial activities by disc diffusion method.

A simple, efficient and cost-effective method has been developed for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones by a one-pot three component cyclocondensation reaction of ethyl aceteoacetate, aromatic aldehydes, and urea/thiourea using sodium nitrate as catalyst. The significant advantages of the present protocol are simplicity, high yields, no chromatographic separation, eco-friendliness and recoverability of the catalyst.

Nigeria is one of the countries of the world with a variety of oil seeds, therefore the potential of Nigeria leading Africa, and the world at large, in the area of seeds oil production was examined by evaluating the oil yield and physicochemical qualities of oil extracted from Citrullus lanatus from the southern region of the country. The lipid content of Citrullus lanatus seeds was found to be 57.26%. The iodine, saponification, acid, free fatty acid, peroxide, specific gravity, refractive index and pH, were analysed using standard procedures and values were found to be 114.94g I₂/100g, 220.19 mgKOH/g, 7.09 mgKOH/g, 4.512%, 20.00 meq/kg, 0.913, 1.35, and 4.45 respectively. The oil contains five main fatty acids: palmitic, stearic, oleic, linoleic are linolenic acids, but the most abundant fatty acid is linoleic with a value of 64.15% which is used industrially as a drying agent in gloss paint. Due to their high oil yield and abundance, oils from Citrullus lanatus seeds may be considered as Nigeria potential asset for soap production and other industrial applications.

An efficient one-pot protocol to generate 4-arylmethyleneisoxazol-5-one derivatives from ethyl acetoacetate, hydroxylamine hydrochloride, and various aromatic aldehydes using sodium azide catalyst in water as environmentally benign solvent has been developed.

Comparative study of O-butylation of phenols under Liquid-Liquid biphasic versus solid-liquid-liquid and Liquid-Liquid-Liquid triphasic phase transfer catalysis has been carried out. 1-Butyl bromide was used as an alkylating agent. Tetrabutyl ammonium hydrogen sulphate was used as Phase transfer catalyst. The rates of reaction were enhanced under the triphasic PTC as compared to the Liquid-Liquid PTC.

Mild and efficient synthesis of 5, 7-dihydroxy-6-methoxy-2-phenyl-4H-chromen-4-one (Oroxylin A) has been reported. MEM is used as protecting group to get Oroxyline A. Screening of protecting groups and solvents system are described in detail. Optimal reaction conditions towards achieving maximum selectivity are discussed. Oroxylin A is characterized by NMR and Mass spectroscopy.

Some aryl chalcones [E-2-Propen-1-ones] have been synthesized using Fly-ash:water catalyzed solvent free Crossed-Aldol reaction between aryl methyl ketones and aryl aldehydes. The yield of chalcones is more than 60%. The purities of these chalcones are checked by their physical constants and spectral data published literature in earlier. The insect antifeedant activities of chalcones have been studied using 4th instar larvae Achoea Janata L.

In this paper, the synthesis of 2-alkenylthieno[3,2-b]thiophene by direct [Pd]-[Cu]-[Ag] catalyzed C-H activation of thieno[3,2-b]thiophene with various alkenes was described. The structures of products 3a-f as well as the site-selectivity of the Heck-type cross-coupling reaction were clarified by NMR and MS analyses.

Newly designed 2-azetidinone derivatives (4a-e) were synthesized in good yields and characterised by advanced spectroscopic studies. The title compounds were evaluated for qualitative (zone of inhibition) by agar diffusion method against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Streptococcus pyogenes. Some of the analogues were found to have comparable or even more potency than the standard drugs. Docking study was performed to check interaction of synthesized compounds with the target DNA gyrase.

The novel organotin(IV) complexes such as (p-ClBz)2SnBr2. Phen(2a) and (p-BrBz)2SnBr2. Phen(2b) were synthesized and characterized employing 1H, 13C and 119Sn NMR analyses. The spectral studies revealed the complex formation of 1,10-phenanthroline with p-substituted diorganotin dibromides at normal reaction conditions. Single crystal diffraction of 2a and 2b has confirmed that the tin atom is in regular octahedral geometry with the benzyl group in the equidirectional position. The structures of these compounds have been characterized by FT-IR, FT-Raman techniques. The optimized geometrical parameters, vibrational wavenumbers, corresponding vibrational assignments of the complexes 2a and 2b have been investigated by means of the density functional theory. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. Moreover, the molecular electrostatic potential surfaces of the complexes have been constructed and electronic property such as HOMO and LUMO energies were also performed.