摘要:
Reaction of 2-amino-6-chloropurine with trans-2-alkyl-5-iodoethyl-1,3-dioxanes under basic conditions afforded N-9 and N-7 alkylated products, the product ratio obtained being dependent on the size of the 2-alkyl group. This allowed a highly regioselective key step in the synthesis of the anti-herpes agent penciclovir.