Understanding the regioselectivity of 5-substituted 1<i>H</i>-tetrazoles alkylation
作者:Guillaume Reynard、Julien Moisan-Labelle、Étienne Parent、Hélène Lebel
DOI:10.1039/d2nj03841b
日期:——
tetrazole (1,5-Tz) in several cases. The regioselectivities (1,5-Tz:2,5-Tz) are highly variable and cannot be exclusively attributed to the steric hindrance of the electrophile. A new rationale to explain the observed regioselectivity, based on the difference in mechanism between first- and second-order nucleophilic substitutions, is thus proposed. In addition, in some cases the intramolecular stabilization
二取代四唑的合成描述了从 1 H -5-单取代四唑通过脂族胺重氮化反应,形成瞬时烷基重氮中间体,充当烷基化剂。尽管 2,5-二取代四唑 (2,5-Tz) 以中等至极好的收率优先形成,但在几种情况下也可以分离出少量的 1,5-二取代四唑 (1,5-Tz)。区域选择性(1,5-Tz:2,5-Tz)是高度可变的,不能完全归因于亲电试剂的空间位阻。因此,基于一级和二级亲核取代之间的机制差异,提出了解释观察到的区域选择性的新原理。此外,在某些情况下,所得重氮的分子内稳定性会影响区域选择性。