Synthesis of oligonucleotides containing 2 '-deoxyisoguanosine and 2 '-deoxy-5-methylisocytidine using phosphoramidite chemistry

摘要

The synthesis of oligonucleotides containing 2'-deoxy-5-methylisocylidine and 2'-deoxyisoguanosine using phosphoramidite chemistry in solid-phase oligonucleotide synthesis is described. Supporting previous observations, the N,N-diisobutylformamidine moiety was found to be a far superior protecting group than N-benzoyl for 2'-deoxy-5-methylisoeylidine. 2'-Deoxy-N-2-[(diisobutylamino)methylidene-5'(4,4'-dimethoxytrityl)-5-meth ylisocytidine 3'-(2-cyanoethyl diisopropylphosphoramidite) (Ic) incorporated multiple consecutive residues during a standard automated synthesis protocol with a coupling efficiency >99% according to dimethoxytrityl release. Extending coupling times of the standard protocol to greater than or equal to 600 s using 2'-deoxy-N-6-[(diisobutylamino)methylidene]-5'-O-(dimethoxytrityl)-O-2-(di phenylcarbamoyl)isoguanosine, 3'-(2-cyanoethyl diisopropylphosphoramidite) (7e) led to successful incorporation of multiple consecutive 2'-deoxyisoguanosine bases with a coupling efficiency > 97% according to dimethoxytrityl release. [References: 25]