Palladium-catalyzed synthesis of natural and unnatural 2-, 5-, and 7-oxygenated carbazole alkaloids from N-arylcyclohexane enaminones.
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 to a Pd(II)-catalyzed cyclization and methylation processes to provide the desired carbazoles, including clausine V. Following an inverse strategy, a new and short total synthesis of glycoborine is also reported.
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. Prol. Carpio y Plan de Ayala, México D.F. 11340, Mexico. jtamariz@woodward.encb.ipn.mx.
Rafael
R
Bautista
Pablo A
PA
Montoya
Araceli
A
Rebollar
Eleuterio
E
Burgueño
Joaquín
J
Tamariz
D000470:Alkaloids / Q000138:chemical synthesis*; D002227:Carbazoles / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D003510:Cyclohexanes / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*
D000470:Alkaloids; D002227:Carbazoles; D003510:Cyclohexanes; D010165:Palladium