Metal- and solvent-free preparation of benzo[4,5]imidazo[1,2-a]pyrimidine derivatives catalysed by deep eutectic solvents
Abstract
Deep eutectic solvents (DESs) were first reported by Abbott and co-workers in 2001 and has since been widely applied to electrolytes, electrodeposition, electropolishing, ionothermal synthesis, gas adsorption, and biotransformation. DESs are classified as a new class of ionic liquids that present many outstanding characteristics such as low vapor pressure, nonflammability, easy preparation, low cost, and large recovery. DESs are classified as a new class of ionic liquids that present many outstanding characteristics such as low vapor pressure, nonflammability, easy preparation, low cost, and large recovery. These characteristics make DESs well-known as green solvents for organic transformations. These characteristics make DESs well-known as green solvents for organic transformations. The Biginelli reaction, first reported in 1891, played an important role in the synthesis of pyrimidine derivatives. A straightforward method for the preparation of benzo[4,5]imidazo[1,2-a]pyrimidine derivatives catalysed by an acidic deep eutectic solvent from choline chloride (ChCl) and phenol via the Biginelli reaction of 2-aminobenzimidazole, ethyl acetoacetate, and aldehydes has been developed under metal- and solvent-free conditions. The desired products were obtained in moderate to good yield (49-79%) and the DESs were known as an economical and environmentally friendly catalyst.
Keywords:
Biginelli reaction, deep eutectic solvents, green catalyst, green chemistryDOI:
https://doi.org/10.31276/VJSTE.63(3).15-17Classification number
2.2

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Published
Received 20 March 2020; revised 5 May 2020; accepted 19 June 2020