Ligand-Enabled Pd(II)-Catalyzed C(sp3)-H Lactonization Using Molecular Oxygen as Oxidant

Pd(II)-catalyzed C-H lactonization of o-methyl benzoic acid substrates has been achieved using molecular oxygen as the oxidant. This finding provides a rare example of C-H oxygenation through Pd(II)/Pd(0) catalysis as well as a method to construct biologically important benzolactone scaffolds. The use of a gas mixture of 5% oxygen in nitrogen demonstrated the possibility for its application in pharmaceutical manufacturing.