Green Method for the Synthesis of Chromeno[2,3-<i>c</i>]pyrazol-4(1<i>H</i>)-ones through Ionic Liquid Promoted Directed Annulation of 5-(Aryloxy)-1<i>H</i>-pyrazole-4-carbaldehydes in Aqueous Media

Abstract

The first classical heterocyclic ionic liquid (IL) promoted C-H bond oxidant cross-coupling reaction for the intramolecular annulation of 5-(aryloxy)-1H-pyrazole-4-carbaldehydes to chromeno[2,3-c]pyrazol-4(1H)-ones has been disclosed. The promoter 1,3-dibutyl-1H-benzo[d][1,2,3]triazol-3-ium bromide can be easily recycled and reused with the same efficacies for at least five cycles in aqueous medium. The strategy works smoothly and provides an applicable protocol to construct a wide range of products.