Acid-Free Synthesis of Carbazoles and Carbazolequinones by Intramolecular Pd-Catalyzed, Microwave-Assisted Oxidative Biaryl Coupling Reactions - Efficient Syntheses of Murrayafoline A, 2-Methoxy-3-methylcarbazole, and Glycozolidine
作者:Vellaisamy Sridharan、M. Antonia Martín、J. Carlos Menéndez
DOI:10.1002/ejoc.200900537
日期:2009.9
A mild and efficient methodology for the synthesis of oxygenated carbazoles from diarylamines under non-acidic conditions was developed, based on a palladium-catalyzed, microwave-assisted double C–H bond activation process. This new protocol was successfully applied to the synthesis of three naturally occurring carbazoles, namely murrayafoline A, 2-methoxy-3-methylcarbazole, and glycozolidine. The
Synthesis of Oxygenated Carbazoles by Palladium-Mediated Oxidative Double C-H Activation of Diarylamines Assisted by Microwave Irradiation
作者:J. Menéndez、Vellaisamy Sridharan、Mª Martín
DOI:10.1055/s-2006-950415
日期:2006.9
Microwave irradiation in the presence of palladium acetate and traces of dimethylformamide allows the fast and efficient cyclodehydrogenation of diphenylamines into carbazoles. The scope of the microwave-assisted reaction is broader than that of the one using conventional conditions in that it allows the preparation of oxygenated carbazoles without apparent loss in yield. The applicability of the method to the preparation of carbazole alkaloids has been demonstrated by the development of a total synthesis of murrayafoline A, which proceeds in 50% overall yield from commercially available materials and is the shortest and most efficient route for the preparation of this alkaloid to date.
Photochemical C-H Activation: Generation of Indole and Carbazole Libraries, and First Total Synthesis of Clausenawalline D
作者:Isak Alimi、Richard Remy、Christian G. Bochet
DOI:10.1002/ejoc.201700300
日期:2017.6.16
N-arylbenzotriazoles leads respectively to indoles and carbazoles. Because the very rapid access to libraries of triazoles, for example by the copper-catalyzed [3+2] cycloaddition between alkynes and azides, this reaction allows the preparation of indoles in a single operation, by the simultaneous photolysis of the precursor library. As an example of such a synthesis of carbazoles, we prepared for the first
A palladium-catalyzed synthesis of the carbazole framework is described, including the preparation of 2-, 5-, and 7-oxygenated natural and unnatural carbazole alkaloids. A series of N-arylcyclohexane enaminones, generated by condensation of cyclohexane-1,3-dione with diverse anilines, were aromatized by a Pd(0)-catalyzed thermal treatment to afford the corresponding diarylamines. The latter were submitted