A microwave-enhanced variation of the Kindler thioamide synthesis is introduced. Taking advantage of the sealed vessel capabilities of a dedicated single-mode microwave reacto,r a diverse selection of 13 aldehyde and 12 amine precursors was utilized in the construction of a representative 34-member library of substituted thioamides. The three-component condensations of aldehydes, amines, and elemental sulfur were carried out using 1-methyl-2-pyrrolidone (NMP) as solvent employing microwave flash heating at 110-180 degrees C for 2-20 min. A simple workup protocol allows the isolation of synthetically valuable primary, secondary, and tertiary thioamide building blocks in 83% average yield and >90% purity.

Four-component reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-carbonitrile with aromatic aldehydes and pyruvic acid or its esters under ultrasonication were studied. Unusual for such a reaction type, a cascade of elementary stages led to the formation of 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines.

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