NUCLEOSIDES .8. SYNTHESIS OF 2',3'-DIDEOXY-2',3'-DIDEOXYISOGUANOSINE AND 2',3'-DIDEHYDRO-2',3'-DIDEOXYISOGUANOSINE AS POTENTIAL ANTIRETROVIRAL AGENTS

2',3'-Didehydro-2',3'-dideoxyisoguanosin (2) and 2',3'-dideoxyisoguano sine (3) have been synthesized by utilizing the Corey-Winter approach starting from isoguanosine. The 6-amino and 5'-hydroxy biprotected iso guanosine derivative was converted to the corresponding 2',3'-thionoca rbonate, which was heated with triethyl phosphite to afford the 2',3'- olefinic product. Either a tert-butyldimethylsilyl or a 4,4'-dimethoxy trityl group was used in the protection of 5'-hydroxy function. Compou nds 2 and 3 were found inactive against human immunodeficiency virus ( HIV), human cytomegalovirus (HCMV), and herpes simplex virus type 1 (H SV-1).