Photoredox-Catalyzed Radical-Radical Cross-Coupling of Sulfonyl Chlorides with Trifluoroborate Salts

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.

Palladium-Catalyzed Decarboxylative Allylic Sulfonylation of Vinyloxazolidine-2,4-diones: Synthesis of γ-Sulfonyl-α,β-unsaturated Amides

A palladium-catalyzed decarboxylative allylic sulfonylation reaction of vinyloxazolidine-2,4-diones with inexpensive and readily available sodium sulfinates as sulfonylation reagents has been developed. Under the catalysis of Pd(PPh3)4, a wide range of γ-sulfonyl-α,β-unsaturated amides can be synthesized in good to excellent yields. The developed protocol is characterized by exclusive regioselectivity, mild reaction conditions, broad substrate scope, good functional group tolerance, and suitable for gram-scale synthesis.

Parallel Minisci Reaction of gem-Difluorocycloalkyl Building Blocks

Parallel Minisci reactions of nonfluorinated and gem-difluorinated C4-C7 cycloalkyl building blocks (trifluoroborates and carboxylic acids) with a series of electron-deficient heterocycles were studied. A comparison of the reaction's outcome revealed better product yields in the case of carboxylic acids as the radical precursors in most cases, albeit these reagents were used with three-fold excess under optimized conditions. The nature of the heterocyclic core was found to be important for successful incorporation of the cycloalkyl fragment. The impact of the CF2 moiety on the oxidation potential of fluorinated cycloalkyl trifluoroborates and the reaction outcome, in general, was also evaluated.

Visible-light-induced photocatalyst-free cascade cyclization of 3-(2-(ethynyl)phenyl)quinazolinones to sulfonated quinolino[2,1-b]quinazolinones

A visible-light-induced K2S2O8-promoted cascade sulfonation/cyclization reaction was established using 3-(2-(ethynyl)phenyl)quinazolinones as efficient substrates under mild conditions. A series of sulfonated quinolino[2,1-b]quinazolinones were successfully synthesized under transition-metal- and photocatalyst-free conditions. Notably, this strategy has the advantages of room temperature and simple operation, easy scale-up, and good functional group tolerance.

Visible-Light Induced Radical Addition-Elimination Reaction for Constructing Allylic Sulfones from Sulfonyl Chlorides and Allyl Bromides

Allyl sulfones are commonly present in bioactive compounds and organic building blocks. This work introduces a photocatalytic radical addition-elimination reaction involving readily accessible sulfonyl chlorides and allyl bromides. It delivers structurally diverse allylic sulfones in moderate to excellent yields, showcasing a high tolerance to functional groups. Notably, this method operates under mild reaction conditions without the need for oxidants, stoichiometric reducing metals, or additives.