Pyrazoles Knoevenagel reaction

Radi M, Bernardo V, Bechi B, Castagnolo D, Pagano M, Botta M (2009) Microwave-assisted organocatalytic multicomponent Knoevenagel/hetero Diels-Alder reaction for the synthesis of 2,3-dihydropyran 2,3-c pyrazoles. Tetrahedron Lett 50 6572-6575... 

Another rapid protocol for the multicomponent microwave assisted organo-catalyst Knoevenagel/hetero Diels-Alder reaction (DKHDA) for the synthesis of substituted 2,3-dihydropyran [2,3-c] pyrazoles (xix) has been developed by Radi et al. [21]. 

Keywords Aldehydes, active methylene compounds, Bestmann-Ohira reagent [dimethyl(dia-zomethyl)phosphonate], potassium hydroxide, methanol, room temperamre, Knoevenagel condensation, one-pot multicomponent reaction, click chemistry, cycloaddition, phospho-nates, regioselective synthesis, phosphonyl pyrazoles... 

Biradar and Sasidhar (2011) reported a new series of novel indole analogs via Knoevenagel condensation and evaluated their in vitro antioxidant and cytotoxin activities using three tumor cell lines. 2,5-Disubstituted indole-3-carboxaldehydes undergo NH OAc catalyzed Knoevenagel condensation with barbiturates, thiazoli-dine-2,4-dione and 3-methyl-lH-pyrazol-5(4H)-one in solvent-free microwave-assisted reaction. 

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