The invention compound 4 - {[(2R, 3S, 4R, 5S) -3- (3- chloro-2-fluoro-phenyl) -4- (4-chloro-2-fluoro-phenyl) -4 cyano-5- (2,2-dimethyl-propyl) -pyrrolidine-2-carbonyl] -amino} -3-methoxy-provides an improved method for the production of acid in a large amount.본 발명은 화합물 4-{[(2R,3S,4R,5S)-3-(3-클로로-2-플루오로-페닐)-4-(4-클로로-2-플루오로-페닐)-4-사이아노-5-(2,2-다이메틸-프로필)-피롤리딘-2-카보닐]-아미노}-3-메톡시-벤조산을 대량으로 제조하기 위한 개선된 방법을 제공한다.