The Synthesis Of 2',3'-seconucleoside Intermediate

The present thesis relates to the synthesis of 2'-O-benzoyl-5'-O-(4,4'-dimethoxytrityl) N⁴-acetyl-2',3'-secocytidine and 2'-O-benzoyl-5'-O-(4,4'-dimethoxytrityl)-N²-isobutyryl-2',3'-secoguanosine. They are an important intermediate for the preparation of oligonucleotide. So the research on synthesis of the nucleoside derivatives was of great practical significanc. The final products were identified by IR and ¹H NMR.The synthesis of 2'-O-benzoyl-5'-O-(4,4'-dimethoxytrityl)-N⁴-acetyl-2',3'-secocytidine comprises the following steps: DMT-Cl(4,4'-dimethoxytritylchloride) reacted with N⁴-acetylcytidine in prydine is converted to 5'-O-(4,4'-dimethoxytrityl)-N⁴-acetylcytidine, which is oxidated by NaIO₄ and reductived by NaBH₄ to give5'-O-(4,4'-dimethoxytrityl)-N⁴-acetyl-2',3'-secocytidine. Acylatel with benzonychloride affords final product in the total yield 41%.Preparation of the 2'-O-benzoyl-5'-O-(4,4'-dimethoxytrityl)-N²-isobutyryl-2',3'-secoguanosine starts from guanosine. Guanosine is acylated by isobutyryl chloride provide N²-isobutyrylguanosine. DMT-Cl reacted with N²-isobutyrylguanosine in prydine is converted to 5'-O-(4,4'-dimethoxytrityl)-N²-isobutyrylguanosine, which is oxidated by NaIO₄ and reductived by NaBH₄ to give 5'-O-(4,4'-dimethoxytrityl)-N²-isobutyryl-2',3'-secoguanosine. Acylatel with benzony chloride affords the key intermediate is formed in 28% yield.