Un-catalyzed tandem Knoevenagel–Michael reaction for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) in aqueous medium

An environmentally benign un-catalyzed one-pot synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) has been reported via tandem Knoevenagel–Michael reaction of aldehydes with two equivalents of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one in aqueous medium.