methyl (methyl 5-acetamido-9-azido-2-thio-3,5,9-trideoxy-D-glycero-D-galacto-2-nonulopyranosid)onate   、                                                                                      
乙酸酐                                                                                                                                                              在
                                                                                                                                                                                 
吡啶   、                                                                                                  
4-二甲氨基吡啶                                                                                                                                  作用下,
                                                                                                                                                                                                                            以90%的产率得到methyl (methyl 5-acetamido-4,7,8-tri-O-acetyl-9-azido-2-thio-3,5,9-trideoxy-D-glycero-D-galacto-2-nonulopyranosid)onate