Methanol → Benzoic acid, 2-iodo-5-methyl-, methyl ester

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Reaktionsschritte

A stirred solution of 2-iodo-5-methylbenzoic acid (17.3 g, 66.0 mmol) and concentrated H2SO4 (3 mL) in MeOH (200 mL) was heated at reflux for 18 h. After this time, the reaction mixture was cooled to rt, concentrated to one third volume, diluted with EtOAc (300 mL), washed with saturated NaHCO3 (2×200 mL), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The resulting residue was dried under high vacuum to afford methyl 2-iodo-5-methylbenzoate as a colorless oil (18.2 g, quant.). 1H NMR (300 MHz, CDCl3) δ 7.84 (d, J=8.1 Hz, 1H), 7.62 (d, J=1.9 Hz, 1H), 6.99-6.96 (m, 1H), 3.92 (s, 3H), 2.33 (s, 3H). A stirred suspension of methyl 2-iodo-5-methylbenzoate (18.2 g, 66.0 mmol), 1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (15.2 g, 73.3 mmol), K2CO3 (27.5 g, 200 mmol), and Pd(PPh3)4 (11.5 g, 9.99 mmol) in 1,4-dioxane (150 mL) and H2O (50 mL) was heated at 100° C. for 18 h under nitrogen. After this time, the reaction mixture was cooled to rt, diluted with EtOAc (400 mL), washed with saturated NaHCO3 (2×300 mL), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The resulting residue was purified by flash column chromatography on silica gel eluting with 0% to 80% EtOAc/hexanes to afford methyl 5-methyl-2-(1-methyl-1H-pyrazol-4-yl)benzoate as a colorless oil (13.3 g, 87%). 1H NMR (300 MHz, CDCl3) δ 7.55-7.25 (m, 5H), 3.94 (s, 3H), 3.80 (s, 3H), 2.38 (s, 3H).

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