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Palladium-Catalyzed α-Arylation of Carboxylic Acid Derivatives with Grignard Reagent



The reaction of arylacetic acid with aryl halides in the presence of a palladium(0) catalyst proceeds with a Grignard reagent (2 equiv.) to afford diarylated acetic acids. Deprotonation was confirmed by treatment with allyl bromide, which revealed that the use of EtMgCl or tBuMgCl at room temperature to 60 °C resulted in complete deprotonation. After deprotonation of (4-methoxyphenyl)acetic acid under such conditions, the resulting mixture was treated with 4-methoxybromobenzene in the presence of Pd(tBu3P)2 (2 mol-%) as a catalyst to give bis(4-methoxyphenyl)acetic acid in 86 % yield. The reaction with several aryl halides under similar conditions gave the corresponding diarylacetic acids.