3-Oxocyclobutanecarboxylic acid (1.0 g, 8.77 mmol) and benzyl alcohol (1.14 g, 10.52 mmol) were used as raw materials, and 3-oxocyclobutanecarboxylic acid was mixed with DIEA (1.92 g, 14.92 mmol) and DPPA (2.89 g, 10.52 mmol) in toluene (8 mL) under argon protection. The reaction mixture was heated to 60 °C and maintained for 3 h. Benzyl alcohol was then added. Stirring was continued at 60 °C overnight. Upon completion of the reaction, the reaction mixture was concentrated and the residue was purified by silica gel column chromatography (petroleum ether:ethyl acetate = 8:1) to afford the target product benzyl 3-oxocyclobutylcarbamate (240 mg, 50% yield). The product was characterized by 1H NMR (500 MHz, CDCl3) and ESI-MS: 1H NMR δ 7.38-7.33 (m, 5H), 5.12 (d, J = 7.5 Hz, 2H), 4.34-4.33 (brs, 1H), 3.44-3.39 (m, 2H), 3.10-3.07 (brs, 2H) ppm; ESI-MS (m/z): 220.2 [M + 1]+.
