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

Abstract

The CÀ 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 Cp E Rh(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 CÀ H alkenylation/deacetylation exhibits solvatochromism.