(2S,4R)-4-(2-chloro-4-fluorophenylthio)-N-(1-cyanocyclopropyl)pyrrolidine-2-carboxamide   、                                                                                      
lithium 1-(1-(ethoxycarbonyl)piperidin-4-yl)azetidine-2-carboxylate                                                                                                                                                                                                                                                                                                          以yielded ethyl 4-(2-((2S,4R)-4-(2-chloro-4-fluorophenylthio)-2-(1-cyanocyclopropylcarbamoyl)pyrrolidine-1-carbonyl)azetidin-1-yl)piperidine-1-carboxylate 1:1 epimers as a white solid (82%)的产率得到4-{2-[(2S,4R)-4-(2-chloro-4-fluorophenylsulfanyl)-2-(1-cyanocyclopropylcarbamoyl)pyrrolidine-1-carbonyl]azetidin-1-yl}piperidine-1-carboxylic acid ethyl ester