Organocatalytic Syntheses of Benzoxazoles and Benzothiazoles using Aryl Iodide and Oxone via C–H Functionalization and C–O/S Bond Formation
摘要:
An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.
Catalyst- and Supporting-Electrolyte-Free Electrosynthesis of Benzothiazoles and Thiazolopyridines in Continuous Flow
作者:Ana A. Folgueiras-Amador、Xiang-Yang Qian、Hai-Chao Xu、Thomas Wirth
DOI:10.1002/chem.201705016
日期:2018.1.9
N‐arylthioamides have been converted to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte‐free reaction, (ii) an easy scale‐up
Copper‐Catalyzed Benzylic C—H Functionalization, Oxidation and Cyclization of Methylarenes: Direct Access to 2‐Arylbenzothiazoles
作者:Wentao Yu、Wanqing Wu、Huanfeng Jiang
DOI:10.1002/cjoc.201900340
日期:2019.11
The direct C—H functionalization of methylarenes is of great significance. Herein, a copper‐catalyzed oxidative C—N/C—S bond formation through benzylic C(sp3)—H functionalization, oxidation and cyclization of methylarenes is reported. Various 2‐arylbenzothiazoles have been synthesized in moderate to excellent yields with readily available o‐iodoaniline, potassium sulfide, and methylarenes as raw materials
Copper‐catalyzed three‐component reactions of 2‐iodoanilines, benzylamines, and sulfur powder are reported to afford benzothiazoles in a simple one‐pot procedure by using water as solvent. A variety of 2‐arylbenzothiazoles were obtained in moderate to good yields up to 88%.
An efficient heterogeneous copper-catalyzed cyclization of o-haloanilides and metalsulfides has been achieved via the C–S coupling in DMF at 80 or 140 °C in the existence of an MCM-41-bound NHC-Cu(I) catalyst and then intramolecular condensation, delivering a wide range of substitutedbenzothiazoles in mostly good to high yields. This new MCM-41-NHC-CuI complex can facilely be obtained by a two-step