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A new approach for the efficient synthesis of imidazo[1,2- a]pyridines is described. The synthesis was carried out via the reaction of functionalized 2-aminopyridine that were formed through a threecomponent reaction and phenacyl bromide derivatives. [ABSTRACT FROM AUTHOR]

Nano magnetic Fe3O4 based vanadic acid [MNPs@VO(OH)2] (average diameter 20-26 nm) has been synthesized by grafting VOCl3 on the Fe3O4 surface nanoparticles as a retrievable supporter to produce novel heterogeneous reusable solid acid with dual ability (Bronsted and Lewis acid) followed by stirring in the air. The resultant material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis and energy-dispersive X-ray spectroscopy (EDX). Significantly, the as-prepared [MNPs@VO(OH)2] exhibits a high catalytic activity in the synthesis of 4,4'-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols). Additionally, the newly synthesized heterogeneous solid acid catalyst can be reused for several times without apparent loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the efficiency, generality and applicability of novel Brønsted acidic ionic liquid triethylamine-bonded sulfonic acid {[Et3N–SO3H]Cl, N,N-diethyl-N-sulfoethanammonium chloride} as homogeneous and green catalyst for organic transformations under various conditions are studied. Herein, the following one-pot multi-component reactions in the presence of {[Et3N–SO3H]Cl are investigated: (i) the synthesis of β-acetamido ketones from acetophenones, aldehydes, acetonitrile and acetyl chloride in solution and under extremely mild conditions (room temperature), (ii) the preparation of 1,8-dioxo-octahydroxanthenes from dimedone (5,5-dimethyl-1,3-cyclohexanedione) (2 equiv.) and aldehydes (1 equiv.) under solvent-free conditions at moderate temperature (80°C), and (iii) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 equiv.) and aldehydes (1 equiv.) in harsh conditions (120°C) in the absence of solvent. High yields, relatively short reaction times, efficiency, generality, clean process, simple methodology, low cost, easy work-up, ease of preparation and regeneration of the catalyst and green conditions (in the synthesis of the xanthene derivatives) are advantages of the application of [Et3N–SO3H]Cl as catalyst in the above organic reactions. This work is the first report of the ionic liquid. [Copyright &y& Elsevier]

Brønstedacidic ionic liquid 3-methyl-1-sulphonic acid imidazoliumchloride {[Msim]Cl} is utilized as a highly efficient, inexpensive, mild and green catalyst for the synthesis of β-acetamido ketones by the one-pot multi-component coupling between acetophenones, arylaldehydes, acetonitrile and acetyl chloride at room temperature. Under these conditions, the title compounds are produced in high to excellent yields and in relatively short reaction times. In addition, this method is superior to reported methods, for the synthesis of β-acetamido ketones and is applicable for the synthesis of tris(β-acetamido ketone). [ABSTRACT FROM AUTHOR]