Ethyl 4-iodobenzoate → Ethyl 4-(3,3-difluorocyclobutanecarbonyl)benzoate

Participants

Reaction Conditions

Reaction Steps

In a 3-neck flask at −30° C. containing ethyl 4-iodobenzoate (600 mg, 2.17 mmol) in anhydrous tetrahydrofuran (6.00 mL) was added isopropylmagnesium chloride lithium chloride complex (1.84 mL, 2.39 mmol) dropwise and then stirred at the same temperature for another 40 min. Copper iodide (124 mg, 0.650 mmol) was then added quickly in one portion. The mixture was brought to −15° C. for 20 min. to ensure the solid has dissolved. The reaction is then brought back to −40° C. Crude 3,3-difluorocyclobutanecarbonyl chloride (470 mg, 1.50 mmol pure) was then added and the reaction was then warmed to 0° C. over 1 h and then stirred at room temperature for 18 h. The mixture was then diluted with 1 N HCl and extracted three times with ethyl acetate. The combined organic layers were then washed with brine and then dried over sodium sulfate, filtered, and concentrated to provide 680 mg of crude oil. Purification by silica gel flash chromatography (0-10% ethyl acetate in heptane) afforded impure ethyl 4-(3,3-difluorocyclobutanecarbonyl)benzoate (130 mg, approximately 0.24 mmol pure) as a solid. 1H NMR (400 MHz, CDCl3) δ 8.09 (d, J=9.0 Hz, 2H), 7.18 (d, J=9.2 Hz, 2H), 4.39 (q, J=7.4 Hz, 2H), 3.34-3.15 (m, 1H), 3.12-2.78 (m, 4H), 1.40 (t, J=7.4 Hz, 3H).

Provenance & Evidence