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