Synthesis of Cyclic Anhydrides via Ligand‐Enabled C–H Carbonylation of Simple Aliphatic Acids

The development of C(sp 3 )–H functionalizations of free carboxylic acids has provided a wide range of versatile C−C and C−Y (Y=heteroatom) bond‐forming reactions. Additionally, C–H functionalizations have lent themselves to the one‐step preparation of a number of valuable synthetic motifs that are often difficult to prepare through conventional methods. Herein, we report a β‐ or γ‐C(sp 3 )–H carbonylation of free carboxylic acids using Mo(CO) 6 as a convenient solid CO source and enabled by a bidentate ligand, leading to convenient syntheses of cyclic anhydrides. Among these, the succinic anhydride products are versatile stepping stones for the mono‐selective introduction of various functional groups at the β position of the parent acids by decarboxylative functionalizations, thus providing a divergent strategy to synthesize a myriad of carboxylic acids inaccessible by previous β‐C–H activation reactions. The enantioselective carbonylation of free cyclopropanecarboxylic acids has also been achieved using a chiral bidentate thioether ligand