Simple and efficient synthesis of trisubstituted imidazoles.

The thermally activated or microwave-induced one-pot three-component condensation of arylglyoxal hydrates, 1,3-dimethylbarbituric acid, and guanidine salts or methylisothiuronium hydroiodide gave respectively 2-amino-5-aryl- and 5-aryl-2-methylsulfanylimidazoles containing a 1,3-dimethylbarbituric acid residue. An unexpected course for the condensation was discovered in the case of guanidine hydrochloride, leading to 5-(2-aryl-2-oxoethyl)-1,3-dimethylbarbituric acids. 2-Amino-2-arylimidazoles under the conditions of such three-component condensation formed Michael adducts involving 5-(2-aryl-2- oxoethylidene)-1,3-dimethylbarbituric acids and the C-5 atom of the imidazole ring. [ABSTRACT FROM AUTHOR]