Ligand‐Dependant Selective Synthesis of Mono‐ and Dialkenylcarbazoles through Rhodium(III)‐Catalyzed C−H Alkenylation

• Published in: Chemistry, an Asian journal Vol. 18; no. 4; pp. e202201210 - n/a
• Main Authors: Tanaka, Rikuto, Ochiai, Shiho, Sakai, Asumi, Usuki, Yoshinosuke, Kang, Bubwoong, Shinada, Tetsuro, Satoh, Tetsuya
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 14.02.2023
• Subjects: Alkenylation; Carbazole; Carbazoles; Catalysts; Cations; Chemistry; C−C coupling; C−H activation; Rhodium; C−C coupling; C−H activation; Rhodium; Alkenylation; Carbazole
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.202201210

The C−H alkenylation of N‐acetylcarbazoles proceeds smoothly at the C1‐position in the presence of a cationic Cp*Rh(III) catalyst to produce 1‐alkenylcarbazoles. The use of a cationic CpERh(III) catalyst enables further alkenylation to give 1,8‐dialkenylcarbazoles. The direct alkenylation procedure in combination with the ready removal of the acetyl directing group provides a straightforward synthetic pathway to 1‐ and/or 8‐alkenyl‐N‐H‐carbazole derivatives. One of 1‐alkenyl‐N‐H‐carbazoles obtained by the present C−H alkenylation/deacetylation exhibits solvatochromism. Selective mono‐ and dialkenylation of N‐acetylcarbazoles was achieved by using Cp*Rh(III)‐ and CpERh(III)‐catalysts, respectively. Unexpectedly, the dialkenylation was accompanied by the removal of acetyl directing group to produce 1,8‐dialkenyl‐N‐H‐carbazoles.