Enabling New Modes of Reactivity via Constrictive Binding in a Supramolecular-Assembly-Catalyzed Aza-Prins Cyclization
作者:David M. Kaphan、F. Dean Toste、Robert G. Bergman、Kenneth N. Raymond
DOI:10.1021/jacs.5b01261
日期:2015.7.29
bimolecular aza-Prins cyclization featuring an unexpected transannular 1,5-hydride transfer. This reaction pathway, which is promoted by constrictive binding within the supramolecular cavity of 1, is kinetically disfavored in the absence of 1, as evidenced by the orthogonal reactivity observed in bulk solution. Mechanistic investigation through kinetic analysis and isotopic labeling studies indicates that
超分子组装 1 催化双分子 aza-Prins 环化,其特征是意想不到的跨环 1,5-氢化物转移。这种反应途径由 1 的超分子腔内的收缩结合促进,在没有 1 的情况下在动力学上是不利的,正如在本体溶液中观察到的正交反应性所证明的那样。通过动力学分析和同位素标记研究进行的机理研究表明,转化的限速步骤是瞬态亚胺离子的封装,并支持拟议的 1,5-氢化物转移机制。这是在催化金属配体超分子酶模拟物中观察到的这种产品选择性极端差异的罕见例子。