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ipso-Defluorinative amination-triggered 1,3-diamination of (trifluoromethyl)alkenes with different amines affords various monofluoroalkenylated acyclic 1,3-diamines in high yields with excellent Z/E selectivity.

The chemo- and regioselective defluorinative [3 + 3] annulation of (trifluoromethyl)alkenes and pyrazolones gives useful 6-fluoro-1,4-dihydropyrano[2,3-c]pyrazoles.

Chiral sulfones, especially those compounds whose sulfone groups are directly connected to the chiral centers, are privileged building blocks in many natural products and bioactive compounds. Thus, the development of novel and efficient methods for the synthesis of these chiral sulfones becomes more important. This review focuses on the recent development of the strategies for the asymmetric synthesis of these compounds, including (1) nucleophilic substitution, (2) hydrosulfonation, (3) cross-coupling reaction, (4) dynamic kinetic resolution, (5) hydrogenation, (6) β-elimination, (7) [3 + 2] cycloaddition, (8) conjugate addition, (9) oxidation of chiral thioethers, and (10) other reactions. The typical reactions, the substrate scope, the reaction mechanism, and their applications in the synthesis of bioactive compounds will be discussed. Given the rapidly increasing interest in this topic, we believe that this review will present a timely and comprehensive understanding of the recent progress in the synthesis of chiral sulfones with sulfone moieties directly connected to the stereocenters.

A double allylic defluorinative alkylation reaction of 1,1-bisnucleophiles with (trifluoromethyl)alkenes is reported that occurs via the exclusively regioselective SN2 reaction. Various aliphatic nitriles, esters, and indolin-2-one derivatives could serve as 1,1-bisnucleophiles, delivering diverse attractive symmetric gem-difluoroalkene substituted products in high yields via the construction of all-carbon quaternary centers. Interestingly, the chemoselective SNV reaction between gem-difluoroalkenes and nucleophiles is completely inhibited. The nitrile group might help to stabilize the α-carbanion intermediates.

A novel and efficient strategy for the transformation of trifluoromethyl ketones is reported. The selective C(α)–C(β) bond cleavage of trifluoromethyl ketones is realized with amidines under air. This transition-metal free reaction system employs green molecular oxygen as an oxidant as well as an O-source, delivering various useful 5-trifluoromethylated imidazol-4-ones in high yields. Preliminary mechanism studies indicate that this reaction proceeds through a 1,2-aryl migration pathway rather than a radical mechanism.

A general and practical method for the synthesis of 5-trifluoromethylpyrazoles is reported that occurs by the coupling of hydrazonyl chlorides with environmentally friendly and large-tonnage industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP). This exclusively regioselective [3 + 2] cycloaddition of nitrile imines and with BTP is catalyst-free and operationally simple and features mild conditions, high yields, gram-scalable, a broad substrate scope, and valuable functional group tolerance. Significantly, our method has been applied for the synthesis of the key intermediate of an active agonist of sphingosine 1-phosphate receptor.

An azide-free strategy for the synthesis of N-2-aryl-1,2,3-triazoles via copper-catalyzed coupling of oxime acetates and aryldiazonium tetrafluoroborates is reported. With the magic p-methoxyphenyldiazonium tetrafluoroborate as the reaction partner, this copper-catalyzed system favored the desired single electron transfer process via N–O bond cleavage of oxime acetates, while the classic single electron transfer process via C–N2 bond cleavage of aryldiazonium tetrafluoroborates was sufficiently inhibited. Significantly, various oxime acetates were suitable for this reaction, delivering the corresponding 4-substituted-N-2-aryl-1,2,3-triazoles and 4,5-disubstituted-N-2-aryl-1,2,3-triazoles in high yield. Primary mechanism studies indicated that this reaction involved a radical procedure. Furthermore, various novel and attractive tetraphenylethylene and carbazole based N-2-aryl-1,2,3-triazoles were synthesized smoothly.

A novel protocol for the synthesis of α-aryl nitriles has been successfully achieved via a copper-catalyzed cyanation of N-tosylhydrazones employing thiocyanate as the source of cyanide. The features of this method include a convenient operation, readily available substrates, low-toxicity thiocyanate salts, and a broad substrate scope.

A novel approach for the synthesis of polysubstituted 3-amino pyrroles via palladium-catalyzed three-component tandem reaction was developed. The procedure constructs various polysubstituted 3-amino pyrroles with moderate to excellent yields under mild reaction conditions with assembly efficiency, readily available starting materials, and good functional group tolerance. Furthermore, this process was successfully applied to the synthesis of different 3-phenyl-1,4-dihydropyrrolo[3,2-b]indole derivatives via an intramolecular Buchwald-Hartwig cross-coupling reaction in two steps.

A copper-catalyzed aerobic oxidative C-C single bond cleavage of acyclic unstrained oxime acetates is reported, providing various aryl nitriles and ketones in good yields. Mechanistic studies indicate a radical procedure is involved in this transformation, and the oxygen atom in the ketone products is originated from O2 in the air. Oxime acetates as an internal oxidant have been proved to be an initiator, which may promote the discovery of novel protocol for C-C bond cleavage and dioxygen activation.

The first attempt at utilizing N-tosylhydrazones as two-carbon synthons has been successfully achieved, which underwent a copper-mediated [3 + 2] oxidative cyclization reaction to afford 2,3,5-trisubstituted furans in moderate to good yields. The features of this method include inexpensive metal catalyst, readily available substrates, high regioselectivity, and convenient operation. The studies provide important approaches for further exploration of the powerful and diverse reaction abilities of N-tosylhydrazones.