2-(2-氯苯基)-1,3-苯并恶唑 在
双氧水 、 palladium diacetate 、 eosin Y disodium salt 、 silver carbonate 作用下,
以
1,4-二氧六环 为溶剂,
以61 %的产率得到2-benzoxazol-2-yl-3-chlorophenol
参考文献:
名称:
H2O2 存在下可见光诱导钯催化含氮杂环芳烃的 CH 羟基化
摘要:
通过钯催化芳烃的 C H 羟基化,以氮杂环为导向基团,过氧化氢为羟基化试剂,开发了一种可见光诱导的酚类化合物合成策略。具有氮杂环导向基团的多种(杂)芳烃可在温和的反应条件下用于邻位CH羟基化,并以良好的收率合成了一系列酚类化合物。该方案具有良好的官能团耐受性和广泛的底物范围,已成功应用于天然产物卡波霉素和药物地拉罗司的合成。根据实验结果和文献调查,光诱导 C 的激进机制提出了 H 羟基化。该方案为通过CH键活化羟基化制备酚类化合物提供了一种新的解决方案。
Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: enhancement of the reaction rate and selectivity by a base
作者:Lin Wang、Zhi-Gang Ma、Xiao-Jing Wei、Qing-Yuan Meng、Deng-Tao Yang、Shao-Fu Du、Zi-Fei Chen、Li-Zhu Wu、Qiang Liu
DOI:10.1039/c4gc00337c
日期:——
An efficient visible-light-driven photocatalytic oxidation of various 2-substituted dihydropyrimidines and phenolic imines has been achieved using an organic photocatalyst eosin Y bis(tetrabutyl ammonium salt) (TBA-eosin Y) and inexpensive oxidant molecular oxygen. With the aid of a base, significantly enhanced photoinduced electron transfer from substrates dihydropyrimidines or phenolic imines to the excited state of TBA-eosin Y has enabled the aerobic oxidation to yield 2-(methylthio)pyrimidines or 2-arylbenzoxazoles selectively.
Palladium catalyzed C<sub>sp2</sub>–H activation for direct aryl hydroxylation: the unprecedented role of 1,4-dioxane as a source of hydroxyl radicals
作者:Kapileswar Seth、Manesh Nautiyal、Priyank Purohit、Naisargee Parikh、Asit K. Chakraborti
DOI:10.1039/c4cc06864e
日期:——
Direct aryl hydroxylation has been achieved via palladium-catalysed Csp2–H activation using versatile directing groups through unprecedented hydroxyl transfer from 1,4-dioxane.
Nickel catalysed construction of benzazoles <i>via</i> hydrogen atom transfer reactions
作者:Amreen K. Bains、Dhananjay Dey、Sudha Yadav、Abhishek Kundu、Debashis Adhikari
DOI:10.1039/d0cy00748j
日期:——
Herein we report a homogeneous, phosphine free, inexpensive nickel catalyst that forms a wide variety of benzazoles from alcohol and diamines by a reaction sequence of alcohol oxidation, imine formation, ring cyclization and dehydrogenative aromatization. A reversible azo/hydrazo couple, that is part of the ligand architecture steers both the alcohol oxidation and dehydrogenation of the annulated amine
Microwave-Assisted Direct Synthesis of 2-Substituted Benzoxazoles from Carboxylic Acids under Catalyst and Solvent-Free Conditions
作者:Asit K. Chakraborti、Raj Kumar、C. Selvam、Gurmeet Kaur
DOI:10.1055/s-2005-868509
日期:——
A direct coupling of carboxylic acids with 2-aminophenol under microwave irradiation has been achieved leading to the synthesis of 2-substituted benzoxazoles under metal and solvent-free conditions. Aliphatic, aromatic and heteroaromatic carboxylic acids provide good yields. Benzoxazole formation takes place in the presence of chloro, methoxy, phenoxy, thiophenoxy, and α,β-unsaturated functionalities. In the case of dicarboxylic acids, the reaction proceeds via the formation of the corresponding anhydride with predominant formation of the mono-benzoxazole.
TEMPO-mediated aerobic oxidative synthesis of 2-aryl benzoxazoles via ring-opening of benzoxazoles with benzylamines
作者:Mugada Sugunakara Rao、Sahid Hussain
DOI:10.1080/00397911.2021.1949476
日期:2021.9.2
Abstract A simple and efficient TEMPO-mediated system for aerobic oxidativesynthesis of 2-aryl benzoxazoles from readily available benzoxazoles and primary benzylic and hetero benzylic amines is presented in one pot. The reaction proceeds through the ring-opening of benzoxazoles and is followed by oxidative condensation with benzylamines. These metal-free, straightforward reactions worked well with a
摘要 一种简单有效的 TEMPO 介导系统,用于从容易获得的苯并恶唑和伯苄基和杂苄基胺有氧氧化合成 2-芳基苯并恶唑。该反应通过苯并恶唑的开环进行,然后与苄胺氧化缩合。这些不含金属的、直接的反应适用于各种底物,在使用空气作为外部绿色氧化剂的温和条件下产生中等至良好的产率。