An efficient method has been developed for the synthesis of a novel series of N-alkyl-2-aryl-5H-imidazo [1,2-b]pyrazol-3-amines in good-to-high yields by the three-component condensation of an aromatic aldehyde, an aminopyrazole, and an isocyanide in acetonitrile with 4-toluenesulfonic acid as a catalyst at room temperature.

Synthesis of N-Alkyl-2-aryl-5H-imidazo[1,2-b]pyrazol-3-amines by a Three-Component Condensation Reaction. -Reaction conditions are optimized for the condensation process. Compared to previous methods, good yields of the title compounds are obtained in short reaction times. -(RAHMATI*, A.; KOUZEHRASH, M. A.; Synthesis 2011, 18, 2913-2920, http://dx.doi.org/10.1055/s-0030-1260154 ; Dep. Chem., Isfahan Univ., Isfahan, Iran; Eng.) -Mais 04-103

A facile synthesis of trans isomers of 4-aryl-3-methyl-6-oxo-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridine-5-carbonitriles via three-component condensation reaction of an aldehyde, 3-amino-5-methylpyrazole and ethyl cyanoacetate in acetonitrile has been developed under microwave irradiation. This one-pot reaction proceeds without any catalyst in short times and gives the product in high selectivities and high yields.

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