The regio- and stereoselective addition of N-heterocycles to alkynes using KOH is reported. Formation of (Z)-isomers and their conversion to (E)-products were found to be dependent upon time as well as the choice of base. Selective attack of N-heterocycles on a more electrophilic alkynyl carbon was supported by DFT calculations, and the stereochemistry of the products was established by X-ray crystallographic
据报道,使用KOH将N-杂环区域和立体选择性地加成到炔烃上。发现(Z)-异构体的形成及其向(E)-产物的转化取决于时间以及碱基的选择。DFT计算支持了N杂环对更具亲电性的炔碳的选择性攻击,并通过X射线晶体学研究和邻卤代炔烃在吲哚-[2,1- a ]异喹啉中的分子内环化作用建立了产物的立体化学。。
Base-catalyzed stereoselective intermolecular addition of imidazoles onto alkynes: an easy access to imidazolyl enamines
作者:Monika Patel、Rakesh K. Saunthawal、Akhilesh K. Verma
DOI:10.1016/j.tetlet.2013.12.100
日期:2014.2
An efficient transition metal-free approach for the regio- and stereoselective addition of imidazoles 1a–f onto alkynes 2a–l to provide the Z- and E isomers of imidazolyl enamines 3a–q and 4a–d using catalytic amount of KOH is described. Stereoselectivity of the addition products (Z and E isomer) was found to be dependent upon time. Competitive experiments show that imidazole is less reactive than
Anti-Markovnikov stereoselective hydroamination and hydrothiolation of (hetero)aromatic alkynes using a metal-free cyclic trimeric phosphazene base
作者:Na Zhao、Chengdong Lin、Lirong Wen、Zhibo Li
DOI:10.1016/j.tet.2019.04.075
日期:2019.6
Hydroamination and hydrothiolation are the most efficient and completely atom-economical process to construct important enamine and vinylsulfide intermediates in pharmaceutical and organic chemistry. The cyclic trimeric phosphazene base (CTPB) showed great catalytic activity for the anti-Markovnikov stereoselective hydroamination and hydrothiolation of alkynes in good to excellent yields. A broad