Yunhe Jin

Copper-Catalyzed Aerobic Oxidative Intramolecular C-H Amination Leading to Imidazobenzimidazole Derivatives

A highly efficient copper-catalyzed aerobic oxidative intramolecular C-H amination has been developed using substituted 2-(1H-imidazol-1-yl)-N-alkylbenzenamines as the starting materials, and the corresponding imidazobenzimidazole derivatives were obtained in excellent yields. This is an economical and practical method for the construction of N-heterocycles.

Installing amino acids and peptides on N -heterocycles under visible-light assistance

Readily available natural α-amino acids are one of nature’s most attractive and versatile building blocks in synthesis of natural products and biomolecules. Peptides and N-heterocycles exhibit various biological and pharmaceutical functions. Conjugation of amino acids or peptides with N-heterocycles provides boundless potentiality for screening and discovery of diverse biologically active molecules. However, it is a great challenge to install amino acids or peptides on N-heterocycles through formation of carbon-carbon bonds under mild conditions. In this article, eighteen N-protected α-amino acids and three peptides were well assembled on phenanthridine derivatives via couplings of N-protected α-amino acid and peptide active esters with substituted 2-isocyanobiphenyls at room temperature under visible-light assistance. Furthermore, N-Boc-proline residue was successfully conjugated with oxindole derivatives using similar procedures. The simple protocol, mild reaction conditions, fast reaction, and high efficiency of this method make it an important strategy for synthesis of diverse molecules containing amino acid and peptide fragments.

An N-(acetoxy)phthalimide motif as a visible-light pro-photosensitizer in photoredox decarboxylative arylthiation

An efficient visible-light photoredox decarboxylative coupling of N-(acetoxy)phthalimides with aryl thiols has been developed. The reaction was performed well at room temperature with good tolerance of functional groups. Importantly, the visible-light photoredox decarboxylative arylthiation did not need an added photocatalyst.

Visible-light photoredox synthesis of unnatural chiral α-amino acids

Unnatural chiral α-amino acids are widely used in fields of organic chemistry, biochemistry and medicinal chemistry, and their synthesis has attracted extensive attention. Although the asymmetric synthesis provides some efficient protocols, noble and elaborate catalysts, ligands and additives are usually required which leads to high cost. Distinctly, it is attractive to make unnatural chiral α-amino acids from readily available natural α-amino acids through keeping of the existing chiral α-carbon. However, it is a great challenge to construct them under mild conditions. In this paper, 83 unnatural chiral α-amino acids were prepared at room temperature under visible-light assistance. The protocol uses two readily available genetically coded proteinogenic amino acids, L-aspartic acid and glutamic acid derivatives as the chiral sources and radical precursors, olefins, alkynyl and alkenyl sulfones, and 2-isocyanobiphenyl as the radical acceptors, and various unnatural chiral α-amino acids were prepared in good to excellent yields. The simple protocol, mild conditions, fast reactions, and high efficiency make the method an important strategy for synthesis of diverse unnatural chiral α-amino acids.

Copper-catalyzed N-arylation and aerobic oxidative C–H/C–H coupling: one-pot synthesis of indoloimidazoquinoline derivatives

A novel and efficient copper-catalyzed one-pot synthesis of indoloimidazoquinoline derivatives has been developed. The protocol uses the readily available substituted 2-(2-bromophenyl)-1H-indoles, imidazole and benzoimidazoles as the starting materials, inexpensive CuBr as the catalyst, air as the terminal oxidant, and the procedure underwent a sequential copper-catalyzed intermolecular N-arylation and an aerobic oxidative intramolecular C–H/C–H coupling.

Visible-Light Photoredox Difluoromethylation of Phenols and Thiophenols with Commercially Available Difluorobromoacetic Acid

A simple and efficient visible-light photoredox one-pot method for difluoromethylation of phenols and thiophenols has been developed. The protocol uses commercially available, inexpensive, and easy handling difluorobromoacetic acid as the difluoromethylating agent, and the diverse O- and S-difluoromethylated products were prepared in good yields with tolerance of many functional groups.

Metal-free UV-Vis-light-induced aerobic oxidative hydroxylation of arylboronic acids in the absence of a photosensitizer

A simple and efficient method has been developed for the metal-free photosynthesis of phenols with UV-Vis (ultraviolet-visible) light in quartz tubes. The protocol uses readily available arylboronic acids as the starting materials, triethylamine as the sacrificial electron donor, and air as the oxidant. The method shows high efficiency, environmental friendliness and mild reaction conditions, without the addition of a photosensitizer.

Visible-Light-Mediated Aerobic Oxidation of N-Alkylpyridinium Salts under Organic Photocatalysis

Quinolones and isoquinolones exhibit diverse biological and pharmaceutical activities, and their synthesis is highly desirable under mild conditions. Here, a highly efficient and environmentally friendly visible light-mediated aerobic oxidation of readily available N-alkylpyridinium salts has been developed with Eosin Y as the organic photocatalyst and air as the terminal oxidant, and the reaction provided quinolones and isoquinolones in good yields. The method shows numerous advantages including mild and environmentally friendly conditions, high efficiency, tolerance of wide functional groups and low cost. Furthermore, 4-desoxylonimide with important pharmaceutical activities was effectively prepared by using our method. Therefore, the present method should provide a novel and useful strategy for synthesis and modification of N-heterocycles.

Easy conjugations between molecules via copper-catalyzed reactions of ortho-aromatic diamines with ketones

It is a great challenge to achieve a useful reaction under benign conditions. In this paper, a highly efficient method for copper-catalyzed conjugations of o-aromatic diamines with ketones has been developed using benign chemistry. Interestingly, the conjugation between the biological small molecules worked very well.