PROBLEM TO BE SOLVED: To provide a method for efficiently producing high purity (3R,4S)-1-(4-fluorophenyl)-[3(S)-hydroxy-3-(4-fluorophenyl)propyl]-(4-hydroxyphenyl)-2-azetidinone in which the amount of specified impurities is reduced.SOLUTION: In the presence of palladium carbon in a catalyst quantity, the deprotection of (3R,4S)-1-(4-fluorophenyl)-[3(S)-hydroxy-3-(4-fluorophenyl)propyl]-[4-(phenyl methoxy)-phenyl]-2-azetidinone is performed, and to produce (3R,4S)-1-(4-fluorophenyl)-[3(S)-hydroxy-3-(4-fluorophenyl)propyl]-(4-hydroxyphenyl)-2-azetidinone, at this time, reaction is performed in such a manner that the pH of a reaction solvent is controlled to 5 or lower.SELECTED DRAWING: NoneCOPYRIGHT: (C)2016,JPO&INPIT【課題】 特定の不純物量が低減した、高純度の(3R,4S)‐1‐(4‐フルオロフェニル)‐[3(S)‐ヒドロキシ‐3‐(4‐フルオロフェニル)プロピル]‐(4‐ヒドロキシフェニル)‐2‐アゼチジノンを効率的に製造する方法を提供する。【解決手段】 触媒量のパラジウム炭素存在下、水素ガスを用いて(3R,4S)‐1‐(4‐フルオロフェニル)‐[3(S)‐ヒドロキシ‐3‐(4‐フルオロフェニル)プロピル]‐[4‐(フェニルメトキシ)‐フェニル]‐2‐アゼチジノンの脱保護を行い、(3R,4S)‐1‐(4‐フルオロフェニル)‐[3(S)‐ヒドロキシ‐3‐(4‐フルオロフェニル)プロピル]‐(4‐ヒドロキシフェニル)‐2‐アゼチジノンを製造する際、反応溶媒のpHを5以下にして反応を行う。【選択図】 なし