4-(3,3-Dimethylcyclobutanecarbonyl)benzoic acid → Tert-butyl 4-(3,3-dimethylcyclobutanecarbonyl)benzoate

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Reaction Steps

To a flask containing 4-(3,3-dimethylcyclobutanecarbonyl)benzoic acid (1.89 g, 8.14 mmol) in anhydrous methylene chloride (20.3 mL) was added 2-tert-butyl-1,3-diisopropylurea (6.28 g, 31.3 mmol). The reaction was refluxed for 24 h. The reaction was then diluted with methylene chloride and quenched with a solution of saturated sodium bicarbonate. The aqueous layer was extracted three times with methylene chloride. The combined organic layers were washed with brine and dried with sodium sulfate, filtered, and concentrated to afford 3.09 g of a crude oil. Purification by silica gel flash chromatography (0-10% ethyl acetate in heptane) provided tert-butyl 4-(3,3-dimethylcyclobutanecarbonyl)benzoate (1.33 g, 57% yield) as a white solid. 1H NMR (400 MHz, CDCl3, δ): 8.08-8.02 (m, 2H), 7.94-7.88 (m, 2H), 3.89 (quin, J=8.8 Hz, 1H), 2.24-2.16 (m, 2H), 2.11-2.02 (m, 2H), 1.62-1.59 (m, 9H), 1.27 (s, 3H), 1.08 (s, 3H). MS (M+1): 289.3.

Provenance & Evidence