Procedures have been developed for the selective formation of (a) 2′,5′-silylated ribonucleosides and (b) 3′,5′-silylated ribonucleosides. These procedures also permit the selective silylation at either the 2′- or 3′-position of dimethoxytritylated ribonucleosides. The procedures involve nitrate or perchlorate ion catalysis for selective reaction at 2′-positions and a combination of silver ion and DABCO or 4-nitropyridine N-oxide for selective reaction at the 3′-position. During the course of this work a general and rapid procedure was developed for the preparation and isolation of the 5′-dimethoxytrityl derivatives of the four common ribonucleosides. Silver ion was found to have a marked effect on dimethoxytritylation reactions.
已开发出用于选择性形成2′,5′-硅烷基化核糖核苷和3′,5′-硅烷基化核糖核苷的程序。这些程序还允许在二甲氧基三苯甲基化核糖核苷的2′-或3′-位置进行选择性硅烷基化。这些程序涉及硝酸盐或高氯酸盐离子催化,用于在2′-位置进行选择性反应,以及银离子和DABCO或4-硝基吡啶-N-氧化物的组合,用于在3′-位置进行选择性反应。在这项工作过程中,开发了一种用于制备和分离四种常见核糖核苷的5′-二甲氧基三苯甲基衍生物的通用和快速程序。发现银离子对二甲氧基三苯甲基化反应有显着影响。