Twenty-nine examples of 2-(9H-carbazol-1-yl)anilines were obtained in yields from 27 to 95% by refluxing 2,3′-biindolyl (1 equiv.) and ketones (1 equiv.) in ethanolic HCl. Alkyl, cyclic, and aryl ketones were found to be compatible with this method, however, aldehydes are not. Because the reaction proceeds by addition of the carbonyl C atom to the biindolyl 3-position, this method has high regioselectivity. One example is presented of bridging the two N atoms in the carbazolylaniline product with an acetaldehyde synthon to give a benzodiazepino[lm]carbazole. Also, one example is given of installing a dimethylamino group at the α-position of the starting ketone to give an indolo[3,2-c]carbazole.
Bibliographical noteFunding Information:
The authors thank undergraduate research assistants, Mark A. Mills and Janel L. Rieger, for preparing several batches of compound 3 , and Andrew K. Schneerer for assistance in the synthesis and isolation of compound 24 . The authors also thank the Wayland E. Noland Research Fellowship Fund at the University of Minnesota Foundation for the financial support of this project.
© 2018 Elsevier Ltd
- Cyclizative condensation
- Substituted carbazoles