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In this paper we describe the electro-oxidation of methyl-substituted aromatic compounds to the corresponding aldehydes in aqueous imidazole ionic liquid (IL) solutions and using a platinum electrode. The electro-oxidative behavior of p -methoxy toluene ( p -MT) was studied in the ILs using cyclic voltammetry (CV), and the oxidation was shown to be an irreversible process. Increasing the acid strength of the ILs led to further oxidation to the corresponding acid. The controlled potential electrolysis of methyl-substituted aromatic compounds was also investigated under the optimized reaction conditions and the products were detected by NMR, IR and gas chromatography/mass spectrometry (GC/MS). The method represents a promising way to prepare aromatic aldehydes. In order to detect intermediates, in-situ Fourier transform infrared spectroscopy (in-situ FTIR) data was acquired during the oxidation processes. The results further confirmed that the procedure provides a selective approach to the synthesis of aromatic aldehydes. The selectivity toward formation of the corresponding aromatic aldehydes was 21–92% when using the optimized reaction conditions. Excellent electrochemical stability of the ILs was demonstrated and they could be recycled at least 35 times. [ABSTRACT FROM AUTHOR]

Citrate trisulfonic acid (CTSA), as a novel recyclable and eco‐benign organocatalyst, was employed for the efficient and one‐pot synthesis of trisubstituted imidazoles and tetrasubstituted imidazoles using aldehydes, ammonium acetate or aniline, and benzoin, benzyl, or 9,10‐phenanthrenequinone under solvent‐free conditions providing high to excellent yields. CTSA is easily prepared via the reaction of trisodium citrate and chlorosulfonic acid in high purity. Compared to the conventional procedures, the present method offers several advantages, including high yields, easy work‐up, short reaction time, reusability of the catalyst, and simple purification of the products. Citrate trisulfonic acid (CTSA), as a novel, recyclable, and eco‐benign organocatalyst, was applied for the efficient and one‐pot synthesis of 2,4,5‐trisubstituted imidazoles and 1,2,4,5‐tetrasubstituted imidazoles using aldehydes, benzoin, benzil or 9,10‐phenanthrenequinone and ammonium acetate or aniline under solvent‐free conditions providing high to excellent yields. CTSA is easily prepared via the reaction of trisodium citrate and chlorosulfonic acid in high purity. [ABSTRACT FROM AUTHOR]

Facile access to diverse C5‐substituted imidazoles and oxazoles via sequential Van Leusen–Suzuki, Van Leusen–Heck, and Van Leusen–Sonogashira protocols, employing imidazolium‐ILs as solvents along with piperidine‐appended imidazolium [PAIM][NTf2] as task‐specific basic IL has been demonstrated, in a high‐yielding one‐pot method, starting with readily available aldimines (for imidazole) or aldehydes (for oxazole) and tosylmethylisocyanide (Tos‐MIC), under mild conditions with potential for recycling and reuse of the IL solvent. The scope of the method is supported 49 examples. By sequencing the Van Leusen imidazole and oxazole syntheses with Suzuki, Heck and Sonogashira reactions, diverse libraries of C5‐functionalized imidazoles and oxazoles were synthesized in one‐pot reactions employing [BMIM][X] as a solvent and [PAIM][NTf2] as a base. [ABSTRACT FROM AUTHOR]

Morpholinium hydrogen sulfate as an ionic liquid was employed as a catalyst for the synthesis of a biologically active series of multi-substituted imidazoles by a four-component reaction involving the combination of benzil with different aromatic aldehydes, ammonium acetate, and 1-amino-2-propanol under solvent-free conditions. The key advantages of this method are shorter reaction times, very high yield, and ease of processing. Furthermore, the resulting products can be purified by a non-chromatographic method and the ionic liquid catalyst is reusable. All of these novel compounds have been fully characterized from spectral data. The X-ray crystal structures of two representative molecules are also detailed. [ABSTRACT FROM AUTHOR]