To a stirred solution of azetidine-3-carboxylic acid methyl ester hydrochloride (762 mg, 4.60 mmoles) and 1-(4-chloro-phenyl)-cyclobutane carboxylic acid (2.09 g, 9.90 mmoles) in anhydrous DCM (20 mL) was added di-isopropyl ethyl amine (4.6 mL, 26.4 mmoles) dropwise. After completion of addition solid PyBroP (4.63 g, 9.94 mmoles) was added to the stirring reaction mixture. The reaction mixture continued stirring at RT for 10 h and was quenched with water. The aqueous layer was extracted with EtOAc (3×20 mL). Combined organic layers were dried over Na2SO4 and concentrated to yield an oil. This crude material was purified using silica gel chromatography (9:1 hexanes:EtOAc-1:1 hexane:EtOAc) to yield the desired amide (1.0 g, 65%). 1H NMR (300 MHz, CDCl3): δ 7.38-7.29 (m, 4H), 4.16 (m, 2H), 3.88 (m, 1H), 3.72 (s, 3H), 3.31-1.63 (m, 8H). LRMS: M+309.
