Guanidine hydrochloride catalyzed efficient one-pot pseudo five-component synthesis of 4,4 '-(arylmethylene)bis(1H-pyrazol-5-ols) in water

摘要

The present methodology describes an efficient, environmentally friendly and simple protocol for the synthesis of some 4,4 '-(arylmethylene)bis(1H-pyrazol-5-ol) derivatives through a one-pot pseudo-five-component reaction of hydrazine hydrate/phenyl hydrazine, ethyl acetoacetate, and various aromatic aldehydes catalyzed by guanidine hydrochloride. This condensation reaction was performed by tandem Knoevenagel-Michael reaction in water under refluxing conditions giving the title compounds in 82-92% yields. Atom economy, simple operation, easy work-up, using inexpensive organocatalyst, high yields in short times, clean transformation, and environmentally benign are some of the important features of this new protocol.