7β-(D-5-carboxy-5-phthalimidovaleramido)-3-hydroxymethylceph-3-em-4-carboxylic acid di-triethylamine salt                                                                                                                                                              在
                                                                                                                                                                                 sodium chloride   、                                                                                                  magnesium sulfate                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
二氯甲烷                                                                                  为溶剂,
                                                                                                                                                                                        以93.2%的产率得到7β-(D-5-phthalimido-5-carboxyvaleramido)-3-(3-oxobutyryloxy)methyl-3-cephem-4-carboxylic acid