by NMR and DFT methods. It was determined that hexamethylphosphoramide (HMPA) can shift the equilibrium of t-BuLi to include the triple ion pair (t-Bu–Li–t-Bu)−/HMPA4Li+ which serves as a reservoir for the highly reactive separated ion pair t-Bu–/HMPA4Li+. Because the Li-atom’s valences are saturated in this ion pair, the Lewis acidity is significantly decreased; in turn, the basicity is maximized
通过NMR和DFT方法详细研究了路易斯碱性
磷酰胺对
叔丁基锂聚集结构的影响。据确定,六甲基
磷酰胺 (HMPA) 可以改变t- BuLi 的平衡,以包含三重离子对 ( t -Bu–Li– t -Bu) - /HMPA 4 Li + ,它充当高反应性分离离子的储存库对t -Bu – /HMPA 4 Li + 。由于该离子对中
锂原子的价态已饱和,
路易斯酸度显着降低;反过来,碱度被最大化,这使得氧杂环内的典型定向效应被覆盖,并且远程 sp 3 C-H 键被去质子化。此外,利用这些新获得的
锂聚集态开发了一种简单的γ-
锂化和苯并二氢
吡喃杂环与各种烷基卤化物亲电子试剂的捕获方案,收率良好。