An aerobic visible-light driven photoredox catalytic formation of 2-substitutedbenzothiazoles through radical cyclization of thioanilides has been accomplished. The reaction features C–H functionalization and C–S bond formation with no direct metal involvement except the sensitizer. The reaction highlights the following: (1) visible-light is the reaction driving force; (2) molecular oxygen is the
Use of Molecular Oxygen as a Reoxidant in the Synthesis of 2-Substituted Benzothiazoles via Palladium-Catalyzed CH Functionalization/Intramolecular CS Bond Formation
作者:Kiyofumi Inamoto、Chisa Hasegawa、Junpei Kawasaki、Kou Hiroya、Takayuki Doi
DOI:10.1002/adsc.201000604
日期:2010.10.4
Molecularoxygen (O2) was successfully employed as a reoxidant in cyclizations of thiobenzanilides 1a–s through a palladium-catalyzed CH functionalization/intramolecular CS bondformation process, leading to an efficient, green method for the synthesis of 2-arylbenzothiazoles 2a–s. Addition of cesium fluoride (CsF) greatly enhanced the reactions, which produced variously substituted 2-arylbenzothiazoles
Desulfurization of thioamides was accomplished using a semicatalytic amount of Bu4NBr. The corresponding amides were obtained in high yields, with good functional group compatibility.
A metal-free approach to N-aryl thioamides fromBuntesalts and anilines in DMSO has been developed. This method tolerated a wide range of functional groups on the aromatic ring, providing an ideal way to N-aryl thioamides in good to excellent yields from cheap and easily available starting materials. A plausible mechanism was also proposed based on the X-ray single crystal diffraction, NMR and MS
Efficient Synthesis of Thiobenzanilides by Willgerodt-Kindler Reaction with Base Catalysts
作者:Takaki Kanbara、Ken Okamoto、Takakazu Yamamoto
DOI:10.1055/s-2007-991073
日期:——
Willgerodt-Kindlerreaction between anilines and ben- zaldehydes readily proceeded in the presence of catalytic amount of Na2S·9H2O to give thiobenzanilides in moderate to good yields. The base catalyst was also available for preparation of primary thiobenzamide.