Protected pent-4-enyl ribosides and deoxyribosides were synthesized as reagents for the preparation of nucleosides and deoxynucleosides. Reaction of pent-4-enyl 2', 3', 5'-tri-O- benzoyl-~-erythro-pentofuranoside with five nucleobases in the presence of N- iodosuccinimidel trifluoromethanesulfonic acid (NIS/TfOH) produced the N-9-&nucleosides in 50-70 96 yields. Pent-4-enyl-2'-deoxy-3', 5'-di-0-p-toluyl-aD-erythro-pentofuranoside ...