Chiral Binaphthyl Box-Copper-Catalyzed Enantioselective Tandem Michael–Ketalization Annulations for Optically Active Aryl and Heteroaryl Fused Bicyclicnonanes

Triflamides and Triflimides: Synthesis and Applications

Among the variety of sulfonamides, triflamides (CF3SO2NHR, TfNHR) occupy a special position in organic chemistry. Triflamides are widely used as reagents, efficient catalysts or additives in numerous reactions. The reasons for the widespread use of these compounds are their high NH-acidity, lipophilicity, catalytic activity and specific chemical properties. Their strong electron-withdrawing properties and low nucleophilicity, combined with their high NH-acidity, makes it possible to use triflamides in a vast variety of organic reactions. This review is devoted to the synthesis and use of N-trifluoromethanesulfonyl derivatives in organic chemistry, medicine, biochemistry, catalysis and agriculture. Part of the work is a review of areas and examples of the use of bis(trifluoromethanesulfonyl)imide (triflimide, (CF3SO2)2NH, Tf2NH). Being one of the strongest NH-acids, triflimide, and especially its salts, are widely used as catalysts in cycloaddition reactions, Friedel-Crafts reactions, condensation reactions, heterocyclization and many others. Triflamides act as a source of nitrogen in C-amination (sulfonamidation) reactions, the products of which are useful building blocks in organic synthesis, catalysts and ligands in metal complex catalysis, and have found applications in medicine. The addition reactions of triflamide in the presence of oxidizing agents to alkenes and dienes are considered separately.

Recent advances in the applications of pyrazolone derivatives in enantioselective synthesis

Pyrazolones and pyrazoles, featuring nitrogen-nitrogen bonds, are two of the most important classes of heterocycles, owing to their widespread occurrence in medicinal chemistry and functional materials. The last decade has witnessed a rapid increase in the construction of chiral pyrazolone and pyrazole derivatives, with the application of pyrazolone derivatives as powerful synthons. Since our last review in 2018, a large number of new achievements has emerged in this area, requiring a timely update. Thus, this review summarizes these elegant achievements based on the multiple reactive sites of different pyrazolone synthons. In addition, important mechanisms and interesting biological investigations relating to the corresponding products are also discussed.

Palladium-Catalyzed Asymmetric Trifluoromethylated Allylic Alkylation of Pyrazolones Enabled by α-(Trifluoromethyl)alkenyl Acetates

The first asymmetric trifluoromethylated allylic alkylation of pyrazolones using α-(trifluoromethyl)alkenyl acetates as a novel trifluoromethylated allylation reagent is described, affording various functionalized chiral pyrazolones containing a trifluoromethylated allyl substituent in high yields with excellent regio-/enantio-/diastereoselectivities. Mechanistically, the double-bond migration of α-(trifluoromethyl)alkenyl acetates in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene is initial and interesting step. More importantly, this study is of significance in providing a novel and widely applicable trifluoromethyl-containing allylation reagent.

Copper-Catalyzed Asymmetric Synthesis of Bicyclo[3.n.1]alkenones

A series of highly strained bicyclo[3.n.1]alkenones have been successfully constructed in good-to-excellent enantioselectivities and moderate-to-good yields via copper-catalyzed formal [3+3] cycloaddition. The versatile chiral cycloadducts could be selectively converted into various valuable bridge systems, which hold considerable potential for the construction of natural and bioactive compounds containing a [3.n.1] moiety.

Cu-Catalyzed Enantioselective Alkylarylation of Vinylarenes Enabled by Chiral Binaphthyl-BOX Hybrid Ligands

Transition-metal-catalyzed radical relay coupling reactions have recently emerged as one of the most powerful methods to achieve difunctionalization of olefins. However, there has been limited success in applying this method to asymmetric catalysis using an effective chiral ligand. Herein we report the Cu-catalyzed enantioselective alkylarylation of vinylarenes using alkylsilyl peroxides as alkyl radical sources. This reaction proceeds under practical reaction conditions and affords chiral 1,1-diarylalkane structures that are found in a variety of bioactive molecules. Notably, a highly enantioselective reaction was accomplished by combining chiral bis(oxazoline) ligands with chiral binaphthyl scaffolds.