Classical chemical sciences
An atom efficient synthesis of polysubstituted dihydropyridine derivatives was accomplished by the one-pot four-component condensation of aldehydes, amines, dialkyl acetylene dicarboxylates and active methylene group-containing compounds such as malononitrile or ethyl cyanoacetate using morpholine as a catalyst at ambient temperature. Broad substrate scope, non-chromatographic purification, good yields of the products makes it be a useful and valuable methodology for employing the 1,4-dipolar intermediates in synthetic organic chemistry. Use of organobase as a single catalyst, room temperature conditions renders the method protocol as a significant addition to the existing methods for the synthesis of multifunctionalized dihydropyridines.
Keywords: One pot; multicomponent; dihydropyridines; morpholine
A series of novel derivatives containing N4-(4-fluorophenyl)-N2-substitured-benzo[d]thiazole-2,4-dicarboxamides were synthesized via an efficient, mild and convenient multistep reaction protocol with excellent yields. The structure of the synthesize compounds were confirmed by IR, 1H NMR, 13C NMR, 19F NMR, mass spectra, elemental analysis and purity was checked by HPLC. All synthesized compounds were screened for anticancer activity against A-549 and Du-145 cancer cell lines by MTT assay. The preliminary bioassay suggests that most of the compounds show anti-proliferation with different degrees. The synthesized compound shows IC50 values in the range of 1.52-17.18 μM in both cell lines. The compounds having electron donating groups had higher anticancer activity compared compounds with electron withdrawing substitutions.
Keywords: Benzo[d]thiazoles; carboxamides; anticancer activity; kinase inhibitors
Linear α-olefins (LAO) with good selectivity toward linear olefins (LO) can be synthesized from widely available fatty acids (lauric, decanoic, miristic, palmitic and stearic acids) in high yield using a Ni(II) complex: Ni(Ph3P)2Cl2 in liquid triphenylphosphine (TPP). It is shown spectrophotometrically, in liquid triarylphosphine that Ni(Ph3P)2Cl2 assumes an octahedral coordination geometry which is believed to be the active species in the dehydration-decarbonylation reaction of fatty acids. For comparison also the Wilkinson's catalyst, i.e., the Rh(I) complex Rh(Ph3P)3Cl was also studied as a fatty acid decarbonylation catalyst in liquid TPP. The Wilkinson's catalyst gives an extremely smooth >95% selectivity toward LAO. Thus, when high LAO selectivity is requested, Rh(Ph3P)3Cl is the catalyst of choice. On the other hand, when economic LO/LAO mixtures are requested in high yields, for instance as in the case of hydroformylation feedstocks, then Ni(Ph3P)2Cl2 is the recommended catalyst. The LO/LAO products were determined with GC-MS and the LAO selectivity was also determined with Raman spectroscopy.
Keywords: Lauric acid; Fatty acids; Ni(Ph3P)2Cl2; Rh(Ph3P)3Cl; Dehydration-decarbonylation; Linear olefins (LO); Linear α-olefins (LAO)
A rapid, green and efficient method for the synthesis of 1,8-dioxooctahydroxanthene and 3,3-arylidenebis(4-hydroxycoumarin) derivatives through a one-pot condensation from various aromatic aldehydes is described using manganese ferrite (MnFe2O4) and cobalt ferrite (CoFe2O4) as promoting material under solvent-free conditions which can easily be recovered and reused. Compared with other synthetic methods, this new method has advantages such as milder reaction conditions, good to excellent yields, short reaction times, and environmentally benign procedure.
Keywords: Solvent-free reaction; 1,8-dioxooctahydroxanthene; 3,3-arylindene bis (4-hydroxycoumarin) derivatives ; reusable promoting material
[DBUH][OAc] (1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate) mediated, green synthesis of 2-amino-6-(1,4-dioxo-3,4-dihydrophthalazin-2(1H)-yl)-4-aryl-4H-pyran-3,5-dicarbonitriles have been synthesized by condensing diethyl phthalate, ethyl cyanohydrazide, benzaldehydes and malononitrile in [DBUH][OAc] medium, at 60-65 oC for 2 h. Particularly valuable features of this method include high yield, broad substrate scope, shorter reaction times and straightforward procedure
Keywords: Diethyl phthalate, benzaldehydes, ethyl cyanohydrazide active methylene compounds; 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate
Chemical and biological aspects of life
Pycnanthus angolensis (Welw.) Warb and Byrophyllum pinnatum (Lam.) Oken are two herbal recipes employed in native medicine for the treatment /management of gastrointestinal disorders, skin infections and more especially cancers, wounds and many other inflammatory conditions. Before now, seven compounds (NG-1b, NG-2, NG-3b, NG-4c, NG-5a, KF-1a and KF-2) have been obtained from the extracts of these plants by column and /or preparative thin-layer chromatographies. The search for new and more active antioxidant agents necessitated the screening of these compounds for potential activity. Generally the isolates gave (IC50) of between 0.50 and 0.60 μg mL-1.However, NG-1b demonstrated a significant activity at 0.48 μg mL-1 which compare favourably with that shown by Vitamin A (a standard antioxidant drug) at 0.49 μg mL-1. These compounds, most especially NG-1b could be further worked on with the aim of improving on the observed antioxidant activity through in-vitro structural activity relationship studies (SARS) and probably in-vivo clinical trials.
Keywords: extracts; isolates; antioxidant; Pycnanthus angolensis; Byrophyllum pinnatum
Industrial and engineering chemistry, biotechnology
The control of impurities at each stage of the purification process of Si is the primary topical problem in Si technology. The technique of determining the impurity composition should be multi-element and with low limit-detection of impurities. From this point of view, X-ray analysis of the phase composition of Si, based on the identification of X-ray diffraction lines is very attractive. Obtaining of Si directly from MG-Si is essential to reveal the physical possibilities of the directional crystallization. In this work, there are considered the options on a set of detectable impurities and the limits of their detection in such type of Si by X-ray diffraction method. It has been shown, that applicability of X-ray analysis of the phase composition of Si, based on the identification of X-ray diffraction lines, depends on the stage of Si purification.
Keywords: Silicon; multi-element analysis; concentration of impurities; detection limits for impurities