We report herein a two‐step one‐pot strategy for the synthesis of benzoxazoles from amides by using cesium fluoride/copper as catalysts. This approach involves the in situ generation of acyl fluorides from the corresponding amides, and the acyl fluorides undergo transamidation and cyclization to give benzoxazoles in good yields. In this work, the amide C−N bonds are activated by CsF to form the acyl
Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
作者:Ramachandra Reddy Putta、Simin Chun、Seung Hyun Choi、Seok Beom Lee、Dong-Chan Oh、Suckchang Hong
DOI:10.1021/acs.joc.0c02191
日期:2020.12.4
the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles
Synthesis of benzoxazoles <i>via</i> the copper-catalyzed hydroamination of alkynones with 2-aminophenols
作者:Kohei Oshimoto、Hiroaki Tsuji、Motoi Kawatsura
DOI:10.1039/c9ob00572b
日期:——
describe herein the synthetic method to benzoxazole derivatives via the copper-catalyzed hydroamination of alkynones with 2-aminophenols. The method produced a wide variety of functionalized benzoxazole derivatives in good yields. Preliminary mechanistic experiments revealed that the reaction would proceed through the copper-catalyzed hydroamination of alkynones and the sequential intramolecular cyclization
Iodine Promoted One-Pot Synthesis of 2-Aryl Benzoxazoles from Amidoximes via Oxidative Cyclization and Ring Contraction
作者:Yong Zhang、Min Ji
DOI:10.1002/ejoc.201901468
日期:2019.12.8
An I2‐promoted sequential oxidative cyclization and ringcontraction reaction is developed for the synthesis of 2‐aryl benzoxazoles by using amidoximes rather than the limited 2‐aminophenols or 2‐haloamides as substrates. This method provides a potential route for introducing certain groups at any site of the 2‐aryl benzoxazole scaffold.
sensitive groups (hydroxyl, cyano, amino, vinyl, ethynyl, ester, and even acetyl groups) and heterocycles, which affords functionalized benzoxazoles in good to excellent yields by employing low catalyst loading (2 mol % Cu). The characterization and plausible catalytic mechanism of Cu(OH)x/OMS-2 are described. The notable features of our catalytic protocol such as the use of air as the benign oxidant