Transition Metals in Organic Synthesis, Part 87: An Efficient Palladium-­Catalyzed Route to 2-Oxygenated and 2,7-Dioxygenated Carbazole Alkaloids - Total Synthesis of 2-Methoxy-3-methylcarbazole, Glycosinine, Clausine L, Mukonidine, and Clausine V

Abstract

P a l l a d i u m -C a t a l y z e d R o u t e t o 2 -O x y g e n a t e d a n d 2 , 7 -D i o x y g e n a t e d C a r b a z o l e A l k a l o i d s Abstract: Optimization of the palladium(II)-catalyzed oxidative cyclization of N,N-diarylamines opens up the way to an efficient synthesis of 2-oxygenated and 2,7-dioxygenated carbazole alkaloids including 2-methoxy-3-methylcarbazole, glycosinine, clausine L, mukonidine, and clausine V.

Palladium-Catalyzed Synthesis of Natural and Unnatural 2-, 5-, and 7-Oxygenated Carbazole Alkaloids from N-Arylcyclohexane Enaminones

“…bis(3-Methoxyphenyl)amine ( 5d ) [26]. Following the procedure described for 5a , with 4d (0.20 g, 0.92 mmol), Pd/C (10%) (0.055 g, 0.052 mmol), K 2 CO 3 (0.190 g, 1.38 mmol) and MeI (0.261 g, 1.84 mmol), 5d (0.171 g, 81%) was obtained as a white solid.…”

“…In spite of the large number of 2-, 5-, 6-, 7-mono- and bis-oxygenated tricyclic natural carbazoles that have been isolated, the wide range of functional groups and substitution patterns that exists among these compounds, and their important pharmacological activity, only recently a considerable number of synthetic approaches for their efficient preparation have been published [1,2,3,24,25,26,27,28,29,30,31,32,33,34,35,36].…”