Palladium-catalyzed oxidative carbonylation of 2-arylphenols throughC-H bond activation and C-C and C-O bond formation under acid-base free and mild conditions has been developed. The reaction tolerates a variety of substrates and provides biologically important benzopyranone derivatives in up to 87% isolated yield.
Synthesis of Lactones via Electrochemical Sequential Oxidative Process
作者:Ming Fang、Peinan Shang、Hai Huang、Jianwei Sun、Zhengyu Han
DOI:10.1002/ejoc.202400557
日期:——
An electrochemical lactone synthesis methodology has been developed, providing a rapid access to various dibenzopyranones from 2-arylbenzaldehyde, besides, 2-arylbenzoic acid could also be transformed into corresponding dibenzopyranones in high efficiency. Various control experiments have been conducted to verify the mechanism of this electrochemical tandem oxidation.
Photocatalytic Dehydrogenative Lactonization of 2-Arylbenzoic Acids
作者:Nieves P. Ramirez、Irene Bosque、Jose C. Gonzalez-Gomez
DOI:10.1021/acs.orglett.5b02269
日期:2015.9.18
A metal-free dehydrogenative lactonization of 2-arylbenzoic acids at room temperature was developed. This work illustrates the first application of visible-light photoredox catalysis in the preparation of benzo-3,4-coumarins, an important structural motif in bioactive molecules. The combination of photocatalyst [Acr(+)-Mes] with (NH4)(2)S2O8 as a terminal oxidant provides an economical and environmentally benign entry to different substituted benzocoumarins. Preliminary mechanistic studies suggest that this reaction most likely occurs through a homolytic aromatic substitution pathway.
Synthesis of dibenzopyranones and pyrazolobenzopyranones through copper(0)/Selectfluor system-catalyzed double CH activation/oxygen insertion of 2-arylbenzaldehydes and 5-arylpyrazole-4-carbaldehydes
作者:Jian Zhang、Dongdong Shi、Haifeng Zhang、Zheng Xu、Hanyang Bao、Hongwei Jin、Yunkui Liu
DOI:10.1016/j.tet.2016.11.069
日期:2017.1
A mild and efficient protocol for the synthesis of dibenzopyranones and pyrazolobenzopyranones was developed involving a copper(0)/Selectfluor system-catalyzed double C-H activation/oxygen insertion of 2-arylbenzaldehydes and 5-arylpyrazole-4-carbaldehydes. Preliminary mechanistic studies suggest that both water and dioxygen act as the oxygen source in the formation of pyranone scaffolds. (C) 2016 Elsevier Ltd. All rights reserved.