Conversion of guanosine into acyclovir and its 6-deoxy derivative

Article abstract of DOI:10.1016/S0040-4020(01)85386-2

2-amino-6-(4-chlorophenylthio)-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl) purine 11, which is readily prepared by allowing the corresponding 6-chloro-compound 10 to react with 4-chloro(thiophenol) and triethylamine in methanol solution at room temperature, reacts with boron trifluoride diethyl etherate in boiling dichloromethane solution to give 2-amino-6-(4-chlorophenylthio)-9H-purine 12 in high isolated yield. 9-[(2-acetoxyethoxy)methyl]-2-amino-6-(4-chlorophenylthio)-9H-purine 13, prepared from the latter aglycone 12 in good yield, is converted by a four-step process into acyclovir 1 and by a two-step process into 6-deoxyacyclovir 2.