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.

Synthesis of Linear Polymers in High Molecular Weights via Reaction-Enhanced Reactivity of Intermediates Using Friedel-Crafts Polycondensation

Linear polymers for many materials applications are popularly produced via step-growth polymerizations of different pairs of A2 and B2 monomers. However, achieving high molecular weights during the synthesis is dramatically limited by the required stoichiometric balance of A and B reactive groups when reactivity is considered unchanged during the polymerization. This short review summarizes the recent progress on using Friedel-Crafts polycondensation reactions to produce high-molecular-weight linear polymers via the reaction-enhanced reactivity of intermediate (RERI) mechanism, in which the reaction of one functional group in the bifunctional monomer spontaneously increases the reactivity of the other functional group on the monoreacted intermediate for faster consumption and connection into polymer chains. Thus, using an excess amount of this monomer produces linear polymers in high molecular weights. Both Friedel-Crafts acylation and hydroxyalkylation reactions have been reported for syntheses of long polymer chains under nonstoichiometric conditions, although the focus is to illustrate the significant progress of applying Friedel-Crafts hydroxyalkylation reactions to produce linear polymers with high molecular weights and varied compositions.