An alternative route to the preparation of (3' → 5') methylene acetal linked di- and trinucleosides

Article abstract of DOI:10.1055/s-1993-25915

Reaction of deoxynucleoside 3'-O-(methylthiomethyl) acetals 1 with N-iodosuccinimide (NlS) and dibutyl phosphate furnished the corresponding 3'-O-(dibutoxyphosphoryloxy)methyl acetals 6. Condensation of the latter with appropriately protected deoxynucleoside acceptors 3, in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf), afforded in most cases the (3' → 5') methylene acetal linked d(B(1Λ) B²) dimers 4. In addition, TMSOTf-promoted coupling of donor 6 (B¹ = C(Bz)) with 3'-O-(methylthiomethyl)thymidine (8) yielded dimer 9. Reaction of 9 with NIS and dibutyl phosphate gave dimer 10, which was applied successfully in the TMSOTf-assisted fusion with acceptors 3 (B² = C(Bz) and A(Bz)), to afford the corresponding trimers d(C(Λ)T(Λ)C) 11 and d(C(Λ)T(Λ)A) 12.