Tatsuya Morofuji

A new approach for electrooxidative coupling of aromatic compounds and primary alkylamines bearing a functional group such as a hydroxyl group and an amino group was developed. The key to the success of the transformation is heterocydization of functional primary alkylamines. Treatment of primary alkylamines bearing a functional group with nitriles or their equivalents gives the corresponding heterocycles. The electrochemical oxidation of aromatic substrates in the presence of the heterocycles followed by chemical reaction under nonoxidative conditions gave the desired coupling products.

A new method for metal-free intramolecular C-H amination has been developed. Electrochemical oxidation of 2-pyrimidyloxybenzenes and 2-pyrimidylthiobenzenes, which can be easily prepared from phenols and thiophenols, respectively, followed by the treatment of the resulting pyrimidinium ions with piperidine gives 2-aminobenzoxazoles and 2-aminobenzothiazoles, respectively.

Dendronized polystyrene having peripheral bromo groups was prepared from the dendronization of unfunctionalized polystyrene with dendritic diarylcarbenium ions bearing peripheral bromo groups using the "cation pool" method. The palladium-catalyzed amination of the peripheral bromo groups with diarylamine gave dendronized polystyrene equipped with peripheral triarylamines, which exhibited two sets of reversible redox peaks in the cyclic voltammetry curves.

A method for the C-N coupling of imidazoles based on electrooxidative C-H functionalization of aromatic and benzylic compounds has been developed. The key to the success is the formation of protected imidazolium ions as initial products, avoiding overoxidation. Deprotection under nonoxidative conditions affords N-substituted imidazoles. Various functional groups are compatible with the present transformation. To demonstrate the power of the method, a P450 17 inhibiter and an antifungal agent having N-substituted imidazole structures were synthesized.

We have developed a new method for C-H amination of aromatic compounds based on electrochemical oxidation of aromatic compounds in the presence of pyridine followed by the reaction of the resulting N-arylpyridinium ions with an alkylamine. This new transformation serves as a powerful method for synthesizing aromatic primary amines from aromatic compounds without using metal catalysts and harsh chemical reagents. High chemoselectivity of the present method is demonstrated by C-H amination of aromatic compounds bearing a nitro group to give a key intermediate for the synthesis of VLA-4 antagonist. © 2013 American Chemical Society.

Dendritic diarylcarbenium ion pools were synthesized by the low temperature electrochemical oxidation of the corresponding dendritic (diarylmethyl)trimethylsilanes, which were prepared by use of the iterative method consisting of electrochemical activation and Friedel Crafts type coupling. Time-course NMR studies revealed that thermal stability of dendritic diarylcarbenium ions depends both on the generation of the dendritic structure and on the para-substituents of the terminal phenyl groups. Dendritic diarylcarbenium ions up to the third generation exhibited high reactivity as a carbon electrophile. (C) 2011 Elsevier Ltd. All rights reserved.

Dendritic diarylcarbenium ions exhibited sufficient electrophilicity to react with unfunctionalized polystyrenes. The polymers obtained by the reaction of the first and the second generation dendritic diarylcarbenium ions with polystyrenes were well characterized by MALDI-TOF MS and SEC-MALLS analyses and observed by AFM.