Lihong Zhou

Selective C–N coupling reaction of diaryliodonium salts and dinucleophiles

N-Aryl-α-amino amides including their chiral isomers have demonstrated important applications as pharmaceutical drugs; however, to date, a one-step synthetic route for them still remains to be developed. Herein, an efficient ligand-free copper-catalyzed selective C–N coupling reaction of diaryliodonium salts and dinucleophiles under mild conditions was realized. Diaryliodonium salts prefer to react with dinucleophiles at the site of stronger alkalic amino groups. Thus, a general aliphatic amino-selective N-arylation of α-amino amides was disclosed. Additionally, copper-catalyzed N-arylation of diaryliodonium salts afforded the same products as obtained via palladium-catalyzed reactions of aryl halides.

Potassium hydroxide-promoted transition-metal-free synthesis of 4(3H)-quinazolinones

We have developed a KOH-promoted transition-metal-free synthesis of 2-substituted 4(3H)-quinazolinones from anthranilamides and benzyl alcohols or cinnamyl alcohol with air as oxidant. The protocol is simple, practical, and cost saving.Graphical abstract

A straightforward green synthesis of N-(tert-butylsulfinyl)imines

A straightforward and environment-friendly protocol for the synthesis of valuable chiral N-(tert-butylsulfinyl)imines has been developed. Different from traditional process with benzaldehydes as substrates, arylmethyl alcohols, benzylthiol, dibenzyl ether, thioether, and disulfide are used as alternative substrates to react with tert-butanesulfinamide in the presence of KOtBu under air for the synthesis of chiral N-(tert-butylsulfinyl)imines. This is a transition metal-free, mild, cost-effective, and simple process.

An environment-friendly synthesis of 4(3H)-quinazolinones

4(3H)-Quinazolinones, a class of important heterocycles, are used extensively in various fields. Although there are a number of synthetic approaches, all of them use catalysts, solvents, chemical oxidants, and/or reagents harmful to the environment when released in large quantities. An environment-friendly, catalyst-free, solventless, one-step synthesis of 4(3H)-quinazolinones is presented. The process involves heating of aldehydes and anthranilamides under air as cheap oxidant and as key promoter of reaction. The protocol is suitable for both aromatic and aliphatic aldehydes. This novel synthetic method may be applied to a wide range of educts, offering high yields at low cost while characterized by minimum environmental impact.

Catalyst-free Synthesis of 2-(tert-Butyldisulfanyl) Heterocycles from tert-Butanesulfinamide and Mercapto-substituted Imidazoles, Tetrazole, Pyrimidine and Pyridine

Organic disulfanes (also named disulfides) play a vital role in chemistry and biology. In particular, unsymmetrical disulfanes are a class of important molecules with bioactivities, such as antitumor activity. There are a number of methods for synthesis of symmetrical disulfides, for example, oxidation of thiols, reductive coupling of sulfonyl chlorides, disulfides exchange. However, the efficient preparation of unsymmetrical disulfides is a far more challenging task. Unsymmetrical S S bond formation is usually accomplished via nucleophilic substitution of S H bonds with sulfenyl derivatives. However, there are shortcomings in some of these methods such as low atomeconomy, harsh reaction conditions or the need to use highly active reagents. All of the reported procedures require catalysts, oxidants or activated sulfides (e. g. alkylthiotrimethylsilanes). Thus, it is useful to develop an efficient and green methodology for synthesis of unsymmetrical disulfanes, especially those bearing heterocycles. Our investigations on sulfinamides and especially our recent report on the CuIcatalyzed synthesis of 2-(tert-butyldisulfanyl) heterocycles, prompt us to disclose a catalyst-free method for the preparation of unsymmetrical disulfides via the reaction of mercapto nitrogen-containing heterocycles with tert-butanesulfinamide (Scheme 1). We first carried out the reaction of 2-mercaptobenzimidazole and tert-butanesulfinamide under the same conditions used for the CuI-catalyzed synthesis of 2-(tert-butyldisulfanyl) heterocycles (Table 2). However, a low yield was obtained under these conditions (Table 1, Entry 1), which impelled us to explore new reaction conditions (Table 1). Replacement of magnesium sulfate with sodium acetate resulted in a small increase in the yield (Entry 2). Reaction performed under argon also led to a modest

CuI-catalyzed synthesis of 2-(tert-butyldisulfanyl) heterocycles from 2-mercaptoheterocycles and tert-butanesulfinamide

The valuable 2-(tert-butyldisulfanyl)heterocycles were effectively synthesized from 2-mercaptoheterocycles and tert-butanesulfinamide via unusual condensation. The reaction between 2-mercapto sulfur-containing heterocycles and tert-butanesulfinamide was performed under ligand-free CuI-catalyzed conditions. The synthetic processes described herein are simple, cost-efficient, and practical. Furthermore, a plausible mechanism is proposed for this transformation.Graphical abstract