(2R-trans)-1-[N-[(1,1-Dimethylethoxy)carbonyl]-O-(phenylmethyl)-L-α-glutamyl]-4-methyl-2-piperidinecarboxylic acid, ethyl ester                                                                                                                                                                                              以
                                                                                         
乙酸乙酯   、                                                                                         
乙腈                                                                                  为溶剂,
                                                                                                                                                                                        以10 g (17 mmol, 98%)的产率得到(2R-trans)-1-[N,N-Bis[(1,1-dimethylethoxy)carbonyl]-O-(phenylmethyl)-L-α-glutamyl]-4-methyl-2-piperidinecarboxylic acid, ethyl ester