Green Method for the Synthesis of Chromeno[2,3-c]pyrazol-4(1H)-ones through Ionic Liquid Promoted Directed Annulation of 5-(Aryloxy)-1H-pyrazole-4-carbaldehydes in Aqueous Media
摘要:
The first classical heterocyclic ionic liquid (IL) promoted C-H bond oxidant cross-doupling,reaction for the intramolecular annulation of 5-(aryloxy)-1H-pyrazole-4-carbal- dehydes to chromeno[2,37c]pyrazol-4(1H)-ones has been disclosed The promoter 1,3-dibutyl-1H-benzo[d]fl 2 3]- triazol-34-ium bromide can be easily recycled reused with the same efficacies for at least five cycles in aqueous medium The strategy works smoothly and provides applicable protocol to construct a Wide range of products.
Intermolecular tandem copper-catalyzed O-arylation-oxidative acylation (cross dehydrogenative coupling-CDC) has been developed under air as an oxidant. The reaction between 2,4-dihydro-3H-pyrazol-3-ones and ortho-halo aryl carboxaldehydes furnished the corresponding chromone fused pyrazoles, in a straightforward manner. The synthetic utility of the presented tandem catalysis has been demonstrated with the synthesis of an A(2)-subtype selective adenosine receptor antagonist in only two steps.[GRAPHICS]