9-(4-Acetoxy-3-acetoxymethylbutyl)-2-amino-6-chloropurine

9-[4-Acetoxy-3-(acetoxymethyl)butyl]-2-amino-6-chloropurine is an impurity of Famciclovir (F101125), an antiviral agent and a prodrug of Penciclovir (P221500).

9-(4-Acetoxy-3-acetoxymethylbutyl)-2-amino-6-chloropurine through a four-step synthesis: steps. 1) Preparation of 1,3-diacetoxy-2-bromopropane: 1,3-Dichloro-2-propanol reacts with potassium acetate and ammonium chloride in DMF. After work-up and reaction with triethylamine hydrobromide, distillation yields the product. 2) Preparation of the zinc reagent: 1,3-Diacetoxy-2-bromopropane reacts with zinc powder and anhydrous lithium bromide in THF, initiated by TMSCl. 3) Preparation of the catalyst: Palladium acetate and S-Phos are stirred in THF under nitrogen. 4) Preparation of the final product: 2-Amino-6-chloro-9-bromoethylpurine, the freshly prepared catalyst, and the zinc reagent react in THF. Work-up and recrystallization from ethanol yield the product.