Controlled Friedel-Crafts Acylation of 3,6-Disubstituted-9H-carbazole

摘要

1,8-Dicarbonylcarbazoles are important starting materials for various applications, especially for pin-cer-type ligands. The convenient synthesis of a series of 1,8-diacyl-3,6-di-tert-butyl-9H-carbazoles (2) by the direct Friedel-Crafts acylation of 3,6-di-tert-butyl-9H-carbazole (1) is described. During the reaction, the dealkylation also occurred, and 1,8-diacetyl-3-tert-butyl-9H-carbazole (4) was isolated as well as characterized by an X-ray diffraction analysis. In addition, the steric bulkiness of the acyl chlorides strongly affects the yields of 1,8-diacylation of 1.