Tandem Knoevenagel–Michael Reaction of 1-Phenyl-3-methyl-5-pyrazolone with Aldehydes Using 3-Aminopropylated Silica Gel as an Efficient and Reusable Heterogeneous Catalyst

Abstract 3-Aminopropylated silica gel is introduced as an efficient, reusable, and thermally stable heterogeneous catalyst for tandem Knoevenagel–Michael reaction of 1-phenyl-3-methyl-5-pyrazolone with aldehydes. Short reaction times, mild reaction conditions, ease of recovery, and catalyst reusability make this method a new, economical, and waste-free chemical process for the efficient synthesis of bis(pyrazolyl)methanes.