Nucleotides New 2-(4-Nitrophenyl)ethyl(Npe)-and 2-(4-Nitrophenyl)ethoxycarbonyl(Npeoc)-Protected 2'-Deoxyribonucleosides and Their 3'-Phosphoramidites-Versatile Building Blocks for Oligonucleotide Synthesis

摘要

A series of new base-protected and 5'-O-(4monomethoxytrityl)-or 5'-O-(4,4'-dimethoxytrityl)-substituted 3'-(2-cyanoethyl diisopropylphosphoramidites) and 3'-[2-(4-nitrophenyl)ethyl diisopropylphosphoramidites] 52-66 and 67-82,respectively,are prepared as potential building blocks for oligonucleotide synthesis (see Scheme).Thus,3',5'-di-O-acyl-and N~2,3'-O,5'-O-triacyl-2'deoxyguanosines can easily be converted into the corresponding O~6-alkyl derivatives 6,8,19,12,14,and 16 by a Misunobu reaction using the appropriate alcohol.Mild hydrolysis removes the acyl groups from the sugar moiety(->9,11,13,15,and 19(vi#alpha# 18),resp.) which can then be tritylated (-> 38-42) and N~2-[2-(4-nitrophenyl)ethoxycarbonyl]-O~6-[2-(4-nitrophenyl)ethyl]-substituted 2'-deoxyguanosines 5 and 7,respectively,are synthesized as new starting materials for tritylation (->28,35, and 37) and phosphitylation (->54f,56,70, and 78).Various O~4-alkylthymidines(see 20-24)are also converted to their 5'-O-dimethoxytrityl derivatives(see 43-47) and the corresponding phosphoramidites (see 62-66 and 79-82).