Ascorbic Acid as an Eco-friendly Catalyst for the Effcient Synthesis of Bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) in Aqueous Media

One-pot, multi-component reaction of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1) and aryl aldehydes 2 or 5-substituted indoline-2,3-diones (4a-c) in the presence of ascorbic acid as a unique catalyst in aqueous media afforded the 4, 4’-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) (3a-f) and 3, 3-bis-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-5-substituted indolin-2-ones (5a-c), respectively. This protocol provides several advantages such as environmental friendliness, excellent yields, and simple workup procedure.