PEG-SO3H as a New, Highly Efficient and Homogeneous Polymeric Catalyst for the Synthesis of Bis(indolyl)methanes and 4,4′-(Arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s in Water

In this work, a green, simple and highly efficient procedure for the synthesis of bis(indolyl)methanes and 4,4'-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s [as an important class of bis(pyrazolyl) methanes] is described. The condensation of indoles or 1-phenyl-3-methylpyrazol-5-one with carbonyl compounds catalyzed by poly(ethylene glycol)-bound sulfonic acid (PEG-SO3H) in water affords the title compounds in high yields and relatively short reaction times.