Effective Palladium-Catalyzed Hydroxycarbonylation of Aryl Halides with Substoichiometric Carbon Monoxide

A protocol
for the Pd-catalyzed hydroxy­carbonylation of aryl
iodides, bromides, and chlorides has been developed using only 1–5
mol % of CO, corresponding to a pCO as
low as 0.1 bar. Potassium formate is the only stoichiometric reagent,
acting as a mildly basic nucleophile and a reservoir of CO. The substoichiometric
CO could be delivered to the reaction from an acyl-Pd­(II) precatalyst,
which provides both the CO and an active catalyst, and thereby obviates
the need for handling a toxic gas.