A stereoselective route to bioactive nucleotide phosphonate analogs

Recently we have reported a novel class of tetrahydrofuran phosphonates of which trans guanine nucleotide analog 1a showed potent antiviral activity as well as antitumor activity. In this paper we describe a stereoselective route where the key step involves an iodoetherification of a α-hydroxyphosphonate to generate the trans tetrahydrofuran with high stereoselectivity. The same intermediate 2 was also used to access the key intermediate for the cis analog 1b.