Generation of chiral N-acylpyridinium ions by means of silyl triflates and their diastereoselective trapping reactions: formation of N-acyldihydropyridines and N-acyldihydropyridones
作者:Cornelia E Hoesl、Markus Maurus、Jörg Pabel、Kurt Polborn、Klaus Th Wanner
DOI:10.1016/s0040-4020(02)00675-0
日期:2002.8
An efficient method for the generation of chiral N-acylpyridinium salts from various pyridines and a chiral acid chloride promoted by means of silyl triflates as additives is presented. The stereoselective addition of organometallic reagents to the intermediate chiral N-acylpyridinium ions led to α-substituted N-acyldihydropyridines and N-acyldihydropyridones in good yields, whereas no or minor amounts
提出了一种由各种吡啶和通过甲硅烷基三氟甲磺酸酯作为添加剂促进的手性酰氯生成手性N-酰基吡啶鎓盐的有效方法。将有机金属试剂立体选择性地添加到中间体手性N-酰基吡啶二鎓离子中,可以以良好的收率得到α-取代的N-酰基二氢吡啶和N-酰基二氢吡啶酮,而当采用标准方法不使用甲硅烷基三氟甲磺酸酯作为添加剂时,则没有或仅有少量的产物。根据使用哪种吡啶或有机金属试剂,观察到良好的非对映选择性。在碱性或还原反应条件下,手性助剂的去除均能顺利进行。