How Small Amounts of Impurities Are Sufficient to Catalyze the Interconversion of Carbonyl Compounds and Iminium Ions, or Is There a Metathesis through 1,3-Oxazetidinium Ions? Experiments, Speculations, and Calculations
作者:Dieter Seebach、Tomohiro Yoshinari、Albert K. Beck、Marc-Olivier Ebert、Alejandro Castro-Alvarez、Jaume Vilarrasa、Markus Reiher
DOI:10.1002/hlca.201400221
日期:2014.9
(Fig. 5). We speculated that an interconversion between iminium and carbonyl species might occur in the absence of H2O or other impurities, i.e., formally a metathesis through 1,3‐oxazetidinium ions (Schemes 2 and 3). A theoretical investigation with various DFT methods, ranging all the way to CCSD(T)/aug‐cc‐pVTZ//MP2/def2‐QZVPP, shows (Figs. 8–11) that oxazetidinium ions are stable species (more or less
在“最佳无水”条件下,我们能够实现,由脯氨酸和新戊醛(或环己酮)衍生的双环恶唑烷酮与(D 6)DMSO和(D 6)苯中添加的羰基化合物平衡。使用(18 O)环己酮时,未观察到标记掺入1,3-恶唑烷酮环中(原位NMR研究;图1、3和4)。由于亚胺基羧酸盐的两性离子可能参与该过程,因此我们还研究了N-异亚丙基-吡咯烷鎓高氯酸盐与环己酮在无水CDCl 3中的反应(图5)。)。我们推测,在不存在H 2 O或其他杂质的情况下,亚胺盐和羰基物质之间可能会发生相互转化,即通过1,3-氧杂氮杂鎓离子形式的复分解(方案2和3)。的理论探讨各种DFT方法,测距一路CCSD(T)/ AUG-CC-pVTZ // MP2 / DEF2-QZVPP,示出了(图8。 - 11),该oxazetidinium离子是稳定物质(或多或少球菌(与亚胺离子+羰基系统反应物充满能量),但是导致这些阳离子的过渡态能量太高,无法在室