Convenient synthesis of anhydrides from carboxylic acids by Mitsunobu reaction under mild conditions

Anhydrides serve not only as highly effective acylating agents but also as pivotal intermediates in organic synthesis, and are therefore widely employed in the construction of polymers, pharmaceuticals, and other commodity chemicals. Despite the availability of various synthetic strategies, existing methods are often hampered by the use of unstable or difficult-to-handle reagents, laborious workup procedures, and a substrate scope largely restricted to symmetrical derivatives. We herein report a convenient and efficient one-step method to anhydrides from carboxylic acids via the Mitsunobu reaction. The protocol accommodates a broad range of both aromatic and aliphatic carboxylic acids under mild and neutral conditions, affording the corresponding symmetrical and unsymmetrical anhydrides in satisfactory yields. This approach addresses key limitations of existing methodologies, offering a practical and versatile alternative for anhydride synthesis.