Three-Component Reactions of α-CF3 Carbonyls, NaN3, and Amines for the Synthesis of NH-1,2,3-Triazoles

Three-Component Sulfonylation and Heteroannulation Enabled by 3-Fold Defluorofunctionalization of Trifluoromethyl Enones

Trifluoromethyl enone emerges as a versatile and multifaceted building block in organic synthesis. A defluorinative heterocyclization reaction of readily available β,β-ditrifluoromethylated enones and biocompatible sodium sulfinates has been developed for the modular synthesis of densely functionalized furans with regio-defined C2,4-bissulfonyl and C3-trifluoromethyl substitutions. This three-component method proceeds through a sequential sulfonylation and intramolecular O-cyclization, enabling the assembly of one furan ring, the formation of C-SO2/C-O bonds, and the cleavage of three C(sp3)-F bonds in a one-pot manner under transition metal-free conditions. Moreover, the obtained furan product can further react with a benzyne precursor to generate 1,4-epoxynaphthalene through a Diels-Alder cycloaddition. The reaction is also distinguished by its broad substrate scope, excellent functional group tolerance, and scalability.

1,2-Oxidative Trifluoromethylation of Olefin with Ag(O2CCF2SO2F) and O2: Synthesis of α-Trifluoromethyl Ketones

A novel and efficient 1,2-oxidative trifluoromethylation of olefins employing Ag(O2CCF2SO2F) as a trifluoromethyl source is described with O2 as the oxidant, which provides access to a variety of valuable α-trifluoromethyl-substituted ketones. The broad substrate scope, feasibility of large-scale operation, and derivatization reactions of α-trifluoromethyl ketones demonstrate the promising utility of this protocol.

Multicomponent cyclization with azides to synthesize N-heterocycles

Heterocyclic compounds, both naturally derived and synthetically produced, constitute a wide variety of biologically active and industrially important compounds. The synthesis and application of heterocyclic compounds have garnered significant attention and experienced rapid growth in recent decades. Organic azides, due to their unique properties and distinctive reactivity, have become a convenient chemical tool for achieving a wide range of heterocycles such as triazoles and tetrazoles. Importantly, the field of multicomponent reaction (MCR) chemistry provides a convergent approach to access various N-heterocyclic scaffolds, offering novelty, diversity, and complexity. However, the exploration of MCR pathways to N-heterocyclic compounds remains incomplete. Here, we review the use of multicomponent reactions for the preparation of N-heterocycles. A wide range of reactions based on azides for the synthesis of various types of N-heterocyclic systems have been developed.

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

Here, we report the first transition-metal-free defluorinative cycloaddition of gem-difluoroalkenes with organic azides in morpholine as a solvent to construct fully decorated morpholine-substituted 1,2,3-triazoles. Mechanistic studies revealed the formation of an addition-elimination intermediate of morpholine and gem-difluoroalkenes prior to the triazolization reaction via two plausible pathways. Attractive elements include the regioselective and straightforward direct synthesis of fully substituted 1,2,3-triazoles, which are otherwise difficult to access, from readily available starting materials.

Combining Hydrodefluorination and Defluorophosphorylation for Chemo- and Stereoselective Synthesis of gem-Fluorophosphine Alkenes

A chemo-, regio-, and stereoselective reaction of trifluoromethyl enones, phenylsilane, and phosphine oxides through a sequential hydrodefluorination and defluorophosphorylation relay is developed for the synthesis of distinctive gem-fluorophosphine alkenes. This multicomponent reaction occurred under transition-metal-free conditions with good functional group tolerance. Moreover, the preinstalled carbonyl auxiliary is important for tuning the reactivity of β-trifluoromethyl enones, thereby enabling controllable and selective functionalization of two fluorine atoms in trifluoromethylated enones.

Amine-Induced Selective C-C Bond Cleavage of 2,2,2-Trifluoroethyl Carbonyls for the Synthesis of Ureas and Amides

An efficient and selective transformation of 2,2,2-trifluoroethyl carbonyls into ureas/amides with amines is reported. This protocol allows the selective cleavage of the C-C bond of 2,2,2-trifluoroethyl carbonyls under transition metal-free and oxidant-free conditions, which is in contrast to the analogous C-F or C-CF₃ bond functionalization. This reaction reveals the unexplored reactivity of 2,2,2-trifluoroethyl carbonyls and exhibits a broad substrate range and good functional group tolerance.

Green Synthesis of Aromatic Nitrogen-Containing Heterocycles by Catalytic and Non-Traditional Activation Methods

Recent advances in the environmentally benign synthesis of aromatic N-heterocycles are reviewed, focusing primarily on the application of catalytic methods and non-traditional activation. This account features two main parts: the preparation of single ring N-heterocycles, and their condensed analogs. Both groups include compounds with one, two and more N-atoms. Due to the large number of protocols, this account focuses on providing representative examples to feature the available methods.

Multiple-fold C–F bond functionalization for the synthesis of (hetero)cyclic compounds: fluorine as a detachable chemical handle

We highlighted the recent advances in the field of multiple-fold C–F bond functionalization for the synthesis of (hetero)cyclic compounds.