The C-H functionalization of organic cations: an interesting and fresh journey.

Organic ionic compounds, especially those with organic cations, are commonly applied in ionic liquids (ILs), organocatalysts, (a)NHC ligands, ion recognition, and optoelectronic materials. The direct C-H functionalization of organic cations offers valuable opportunities for the rapid assembly of diverse functionalized cations and for their further exploitation in material science applications. This review summarizes the substantial progress that has been made in the C-H functionalization of organic cations from the 1960s to May 2020, including transition metal-mediated/catalyzed C-H alkylation, arylation, and annulation, and photo-induced C-H functionalization. Substrate scopes, limitations, regio-/chemoselectivity, and reaction mechanisms are discussed. In addition, the applications of some new organic functional materials are briefly exemplified. This review also aims to serve as a reminder that much care should be taken when using organic ionic compounds as solvents, because they can behave as reactants that can break up desired coupling reactions.

Cu-Catalyzed tandem N-arylation of phthalhydrazides with cyclic iodoniums to yield dihydrobenzo[c]cinnolines.

Dihydrocinnolines have significant pharmacological properties. Herein, we investigate a Cu-catalyzed tandem N-arylation reaction of phthalhydrazides with cyclic iodonium salts to construct dihydrobenzo[c]cinnoline derivatives. Various iodonium salts, such as symmetrical, unsymmetrical, aryl-aryl, and aryl-heteroaryl ones, could react with phthalhydrazides smoothly and give the title products in moderate to high yields. Moreover, the -NH2 group, which has been diarylated by cyclic iodonium salts to form carbazoles in previous reports, is also well tolerated in this work.

The C-H Activation/Bidirecting Group Strategy for Selective Direct Synthesis of Diverse 1,1'-Biisoquinolines.

Multidentate ligands are highly important but difficult to access. Herein we disclose an atom- and step-economic synthesis of highly substituted 1,1'-biisoquinolines by a C-H activation/bididirecting group strategy. Through rational design of a bididirecting group to "N-OH + N-OAc", selective unsymmetrical diannulation with two different alkynes in a one-pot reaction has been achieved for the first time to access unsymmetrical biisoquinolines. Moreover, the resultant biisoquinolines show tunable photoluminescence and serve as aggregation-induced emission (AIE) systems.

Domino N-/C- or N-/N-/C-arylation of imidazoles to yield polyaryl imidazolium salts via atom-economical use of diaryliodonium salts.

Herein, we disclose a Cu-mediated domino di-/triarylation reaction of imidazoles to efficiently access polyaryl imidazolium salts in a single step by using two aryls as well as an anion of a diaryliodonium salt. The diarylation shows high atom economy and excellent selectivity with unsymmetrical iodonium salts.