One-Pot, Three-Component Approach to the Synthesis of 3,4,5-Trisubstituted Pyrazoles.

The mechanistically novel one-pot, three-component coupling of aldehydes, dicarbonyls, and diazo compounds proceeds by a tandem Knoevenagel condensation, 1,3-dipolar cycloaddition, and transition metal-free oxidative aromatization reaction sequence involving the cleavage of an acetyl group for pyrazole formation.