Tandem cyclocondensation-Knoevenagel–Michael reaction of phenylhydrazine,acetoacetate derivatives and arylaldehydes, in the presence of isonicotinic

Bis(pyrazolyl)methanes such as 4,4 ׳-(arylmethylene)-bis(3-methyl-1-phenyl-1Hpyrazol-5-ol)s being used as anti-inflammatory, antipyretic, gastric secretion stimulatory, antidepressant, antibacterial and antifilarial agents [1, 2]. Moreover, these compounds have been applied as fungicides [3], pesticides [4] and insecticides [5, 6]. The most common protocols for the synthesis of 4,4´-(arylmethylene)bis(1Hpyrazol- 5-ol)s is one-pot three-component condensation reaction of various aldehydes with 3-methyl-1-phenyl-5-pyrazolone using different catalysts [6]. Having this issue in mind, we have introduced isonicotinic acid as an efficient and homogeneous catalyst for the preparation of 4,4´-(arylmethylene)bis(3-methyl-1- phenyl-1H-pyrazol-5-ol)s via one-pot pseudo five component condensation reaction of phenylhydrazine and ethyl acetoacetate with various aromatic aldehydes at 80 °C under solvent-free conditions (scheme 1).