Ruthenium(II)‐Catalyzed C‐H Annulation of Aromatic Acids with Alkynes Using Air as the Sole Oxidant in Water

A facile synthesis of isocoumarin and α‐pyrones derivatives by Ru(II)‐catalyzed oxidative annulation of aromatic acids and alkynes is reported. This reaction could undergo smoothly in water by use of air as the sole oxidant and accomplishes with the tolerance of a wide range of functional groups. Additionally, the oxidative cyclization of benzoic acid and acrylate is also achieved in the same conditions to furnish the isobenzofuran‐1(3H)‐one scaffold. A facile synthesis of isocoumarins and α‐pyrones through ruthenium‐catalyzed aerobic C−H annulation of aromatic acids with alkynes in water is reported, in which air was used as the sole oxidant.