Catalyst free Michael addition of 3-methyl-2-pyrazolin-5-one to β-nitrostyrenes ‘on water’: a green protocol for facile synthesis of 4-(1-aryl-2-nitroethyl)-3-methyl-1H-pyrazol-5-ol

A highly efficient and green protocol has been developed for the synthesis of 4-(1-aryl-2-nitroethyl)-3-methyl-1H-pyrazol-5-ol via Michael addition of 3-methyl-2-pyrazolin-5-one with β-nitrostyrenes under catalyst free conditions on aqueous medium. A series of 4-(1-aryl-2-nitroethyl)-3-methyl-1H-pyrazol-5-ols have been synthesized with good to excellent yield. C-alkylated product was observed exclusively with 3-methyl-2-pyrazolin-5-one without formation of N-alkylated product.