5-acetamido-7,8,9-tri-O-acetyl-2,6-anhydro-4-(4-tert-butoxycarbonylamino)butylamino-3,4,5-trideoxy-D-glycero-D-galacto-non-2-enonic acid methyl ester   、                                                                                      
N,N'-bis-Boc-S-methyl-isothiourea                                                                                                                                                              在
                                                                                                                                                                                 
三乙胺   、                                                                                                  mercury dichloride                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
N,N-二甲基甲酰胺                                                                                  为溶剂,
                                                                                                                                                    反应 3.0h,
                                                                                                                以88%的产率得到5-acetamido-7,8,9-tri-O-acetyl-2,6-anhydro-4-[N',N''-di(tert-butoxycarbonyl)-N-(4-tert-butoxycarbonylaminobutyl)guanidino]-3,4,5-trideoxy-D-glycero-D-galacto-non-2-enonic acid methyl ester