Palladium/Copper-Catalyzed Denitrogenative Alkylidenation and -Alkynylation Reaction of 1,2,3-Benzotriazin-4(3)-ones.

An efficient palladium-catalyzed approach to access various functionalized ()-3-benzylidene-isoindoline-1-ones and ()-3-benzylidene(imino)isobenzofuranones via a denitrogenative tandem alkynylation/cyclization reaction of 1,2,3-benzotriazin-4(3)-ones with aromatic terminal alkynes is described. Furthermore, a denitrogenative -alkynylation reaction of 1,2,3-benzotriazinones with aliphatic terminal alkynes is also developed. The reaction proceeds through a five-membered azapalladacyclic intermediate with the extrusion of a nitrogen molecule. The significance of the reaction is also demonstrated by a one-pot synthesis of ()-3-benzylideneisobenzofuran-1(3)-one derivatives in good to high yields.