cis‐pyridinium‐type salts. These salts reacted with various nucleophiles, such as alcohols, azides, and organozinc reagents, to form nucleophilic‐substitution products. A characteristic feature of these processes was that they took place under mild conditions, which did not affect acid‐labile protecting groups. Furthermore, the reactions that employed azides and C‐nucleophiles generated 2,6‐trans products with high
已经开发了通过
吡啶鎓型盐中间体进行的
四氢吡喃基(THP)和相关的
碳水化合物衍生的酯的异头位置的亲核取代。用TMSOTf(TMS =三甲基甲
硅烷基)和2-取代的
吡啶(例如2-对-
甲苯基
吡啶和
2-甲氧基吡啶)处理6-取代的α-乙酰氧基-
四氢吡喃可有效产生顺式py型盐。这些盐与各种亲核试剂(例如醇,
叠氮化物和
有机锌试剂)反应,形成亲核取代产物。这些过程的一个特征是它们发生在温和的条件下,并不影响对酸不稳定的保护基团。此外,使用
叠氮化物和C-亲核试剂的反应生成具有高立体选择性的2,6-反式产物。