Efficient iodine-catalyzed one pot synthesis of highly functionalised pyrazoles in water

An efficient one pot multi-component sequential reaction of phenyl hydrazine, malanonitrile and a diverse range of aldehydes to afford highly functionalised pyrazoles is reported. The reaction proceeds in water using molecular iodine as a catalyst, with no by-product formation, and involves simple operation requiring no column chromatography. Thus, this protocol fulfils all of the criteria that define green chemistry.