Substrate-Controlled Regiodivergent Synthesis of Fluoroacylated Carbazoles via Friedel-Crafts Acylation.

A general, efficient, and substrate-controlled regiodivergent trifluoroacetylation of carbazoles has been developed through Friedel-Crafts acylation. This strategy was applicable to a wide scope of readily available substituted carbazoles at air atmosphere without using a metal catalyst, affording the corresponding trifluoroacetylated carbazoles in up to 99% yield. The divergency of the products and the orientation rules have been illustrated based on different substituents on carbazole rings. This method could also be extended to the synthesis of chlorodifluoroacetylated and pentafluoropropionylated carbazoles, which have been achieved for the first time.