Palladium‐Catalyzed Carboxylation of Benzyl Chlorides with Atmospheric Carbon Dioxide in Combination with Manganese/Magnesium Chloride

An efficient direct carboxylation of a series of benzyl chlorides with CO 2 catalyzed by Pd(OAc) 2 /dicyclohexyl (2′,6′‐dimethoxy‐[1,1′‐biphenyl]‐2‐yl)phosphine (SPhos) was developed to afford the corresponding phenylacetic acids in combination with Mn powder as a reducing reagent and MgCl 2 as an indispensable additive. The reaction proceeded smoothly under 1 atm CO 2 . The application of Mn powder instead of a sensitive reducing reagent represents an operationally simple access to phenylacetic acids. Notably, MgCl 2 is able to stabilize the (SPhos) 2 Pd II (Bn)(Cl)(η 1 ‐CO 2 )(MgCl 2 ) adduct and thus facilitates CO 2 insertion into the Pd II −C bond, which is supported by a DFT study.