Metal-Free Synthesis of 2-Substituted (N, O, C) Benzothiazoles via an Intramolecular C−S Bond Formation
作者:Enguang Feng、He Huang、Yu Zhou、Deju Ye、Hualiang Jiang、Hong Liu
DOI:10.1021/cc9001839
日期:2010.7.12
convenient method was developed for the preparation of 2-substituted (N, O, C) benzothiazoles from N'-substituted-N-(2-halophenyl)thioureas, O'-substituted-N-(2-halophenyl) carbamothioates, or N-(2-halophenyl) thioamides via a base-promoted cyclization in dioxane without any transition metal. A one-pot variant combining the synthesis of the thiourea and the cyclization was also demonstrated. High yields
Heterocycle Formation via Palladium-Catalyzed Intramolecular Oxidative C−H Bond Functionalization: An Efficient Strategy for the Synthesis of 2-Aminobenzothiazoles
作者:Laurie L. Joyce、Robert A. Batey
DOI:10.1021/ol900958z
日期:2009.7.2
N-Arylthioureas are converted to 2-aminobenzothiazoles via intramolecular C−S bond formation/C−H functionalization utilizing an unusual cocatalytic Pd(PPh3)4/MnO2 system under an oxygen atmosphere at 80 °C. This method eliminates the need for an ortho-halo substituted precursor, instead achieving direct functionalization of the ortho-aryl C−H bond. Mechanistic observations, including a large intramolecular
A Mild and Efficient One-Pot Synthesis of 2-Aminated Benzoxazoles and Benzothiazoles
作者:Gavin W. Stewart、Carl A. Baxter、Ed Cleator、Faye J. Sheen
DOI:10.1021/jo900308t
日期:2009.4.17
Previous syntheses of the biologically active 2-aminated benzoxazoles have relied on forcing thermal conditions to generate the products directly from the corresponding thiols. The resulting yields have ranged from moderate to poor. A mild and high-yielding alternative one-pot chlorination-amination procedure is described. Compounds with a variety of substitution patterns are reported and the methodology has been successfully extended to benzothiazoles. Palladium catalysis on suitably activated examples has been employed to generate the desired compounds of interest.