Pd-Catalyzed C-H arylation of pyridazine-based fused 1,2,4-triazoles: overriding selectivity at the usual position by undermining of preferred chelate formation.

The applicability of C-H functionalization to medicinally important 2-pyridyl-based N-heterocycles suffers from severe challenges owing to the high Lewis basicity of the N-atom. This arrests catalytic activity and yields undesirable positional selectivity due to preferential chelate formation. In this regard, we report a novel palladium(ii)-catalyzed arylation strategy on multiple-N-containing pyridazines by over-riding the functionalization due to a chelated palladacycle.

Expedient synthesis of new cinnoline diones by Ru-catalyzed regioselective unexpected deoxygenation-oxidative annulation of propargyl alcohols with phthalazinones and pyridazinones.

Ruthenium-catalyzed simple, cascade and one-pot synthesis of cinnoline-fused diones has been carried out by the C-H activation of phthalazinones/pyridazinones accomplished by the unusual deoxygenation of propargyl alcohols. The bond selectivity is accredited to the traceless directing nature of the hydroxyl group of propargyl alcohol. A sequential C-H activation, insertion and deoxy-oxidative annulation has been proposed based on the preliminary mechanistic study.