One-Pot Regio- and Stereoselective Cyclization of 1,2,<i>n</i>-Triols
作者:Tao Zheng、Radha S. Narayan、Jennifer M. Schomaker、Babak Borhan
DOI:10.1021/ja043002i
日期:2005.5.1
A simple and efficient process to cyclize triols containing a 1,2-diol functionality with a pendant hydroxyl group is presented. The one-pot procedure converts the 1,2-diol into an ortho ester in situ, which upon treatment with a Lewis acid generates a cyclic acetoxonium intermediate. This intermediate is subsequently trapped by the pendant hydroxyl group to generate a cyclic ether. The stereochemistry
6-triisopropylphenyl) disulfide, an inexpensive reagent with relatively low oxidative ability, as a photo and hydrogen atom transfer catalyst to achieve intramolecular hydroamination. The mechanistic studies as well as the DFT calculations are consistent with a novel process involving N-centered radical generation through the homolysis of the in situ formed N–S species and subsequent cyclization. An
烯烃的光诱导反马尔可夫尼科夫加氢胺化通常需要具有高氧化能力的光催化剂来引发单电子过程。在此,我们交替使用双(2,4,6-三异丙基苯基)二硫化物,一种氧化能力相对较低的廉价试剂,作为光和氢原子转移催化剂来实现分子内加氢胺化。机理研究以及 DFT 计算与涉及通过原位形成的 N-S 物种均裂和随后的环化产生 N 中心自由基的新过程一致。可以获得一系列不同的含氮循环。