Tetrahydrofuran → 3-(2-Chloro-4-nitrobenzoyl)-4-methylbenzoic acid methyl ester

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A dry flask was charged with 3-iodo-4-methylbenzoic acid methyl ester (21.6 g, 78.2 mmol) and the flask was evaporated and then filled with argon and this process repeated twice. Dry THF (140 mL) was added, and the solution cooled to −50° C.; then isopropylmagnesium chloride (41 mL, 2.0 M in diethyl ether, 82 mmol) was added slowly over 15 min keeping the temperature below −40° C. On completion of the addition the reaction mixture was stirred at −40° C. for 45 min. A THF solution of ZnCl2 (10.78 g, 79.1 mmol, 0.8 M) was added dropwise over 20 min. The reaction mixture was stirred at 0° C. for 65 min; then 2-chloro-4-nitro-benzoyl chloride (17.2 g, 78.2 mmol) and tetrakis(triphenylphosphine)palladium(0) (4.03 g, 3.49 mmol) were added and the reaction mixture was allowed to warm to room temperature. After 4 h the reaction mixture was poured into a mixture of toluene/EtOAc/water, then shaken and separated. The aqueous phase was extracted with two more portions of EtOAc. The organic phases were combined, dried (MgSO4), filtered, and concentrated in vacuo to afford the crude product. Crystallization from mixtures of EtOAc/petroleum ether (40-60) gave the title compound as yellow solid. The mother liquid was concentrated in vacuo and purified by chromatography using DCM as the eluent to give a second crop of the title compound.

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