3-Methylenecyclobutanecarboxylic acid (11.0 g, 98.1 mmol) and potassium carbonate (27.1 g, 196 mmol) were dissolved in acetone (100 mL), and dimethyl sulfate (14.8 g, 117 mmol) was slowly added at 25 °C. The reaction mixture was heated to 70 °C and maintained for 12 hours. Upon completion of the reaction, water (20 mL) was added to quench the reaction, followed by extraction with dichloromethane (30 mL x 3). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to afford methyl 3-methylenecyclobutanecarboxylate (12.0 g, yellow oil) in 97% yield.
