据报道,氢化钌/布朗斯台德酸催化的串联序列可用于合成1,3,4,9-四氢吡喃[3,4- b ]吲哚(THPIs)和相关的氧环骨架。该过程被设计的前提是容易得到的烯丙基醚将经历连续的异构化,第一至烯醇醚(RU催化),然后到oxocarbenium离子(布朗斯台德酸催化)适合于内 环化栓系亲核体。该方法不仅为合成THPI的传统oxa-Pictet-Spengler反应提供了有吸引力的替代方法,而且还方便地获得THPI同类物和其他重要的乙环(如乙缩醛)。
Tandem Olefin Isomerization/Cyclization Catalyzed by Complex Nickel Hydride and Brønsted Acid
作者:Prasad M. Kathe、Alexandru Caciuleanu、Andreas Berkefeld、Ivana Fleischer
DOI:10.1021/acs.joc.0c02033
日期:2020.12.4
We disclose a nickel/Brønsted acid-catalyzed tandem process consisting of double bond isomerization of allyl ethers and amines and subsequent intramolecular reaction with nucleophiles. The process is accomplished by [(Me3P)4NiH]N(SO2CF3)2 in the presence of triflic acid. The methodology provides rapid access to tetrahydropyran-fused indoles and other oxacyclic scaffolds under very low catalyst loadings