Palladium-catalyzed synthesis of carboxylic acid anhydrides from alkenes

Hydrocarbonylation of alkenes with nucleophiles - water, alcohols and amines, is widely studied and implemented in synthesis of fine chemicals and natural products. Here, an efficient and additive-free palladium catalyzed hydrocarbonylation reaction of alkenes is described using carboxylic acids as the nucleophile, by which acid anhydrides are obtained in moderate to excellent yields. The relative concentrations of substrate and reagents play an important role in driving the reaction forward, which reaches an equilibrium at equimolar concentrations under a given CO pressure. A ligand-screening study revealed the use of electron-poor phosphine ligands to be crucial for obtaining higher rates of the catalytic reaction. Several substrates including unactivated alkenes were successfully converted to the corresponding symmetric as well as mixed anhydrides. An additional advantage of our synthetic procedure is that the obtained anhydrides can be converted to (primary) amides, thioesters or esters in situ via a simple one-pot derivatization reaction, since acid anhydrides are prone to degradation on isolation.