Cu-Catalyzed Stereoselective Borylation of gem-Difluoroalkenes with Bpin.

A novel and efficient method for the synthesis of (Z)-fluorinated alkenylboronic acid pinacol esters via Cu-catalyzed stereoselective borylation of gem-difluoroalkenes using bis(pinacolato)diboron (Bpin) as the boron source with the assistance of NaOtBu and Xantphos at room temperature was developed.

Sterically Controlled Cu-Catalyzed or Transition-Metal-Free Cross-Coupling of gem-Difluoroalkenes with Tertiary, Secondary, and Primary Alkyl Grignard Reagents.

A robust copper-catalyzed or transition-metal-free cross-coupling of gem-difluoroalkenes with tertiary, secondary, and primary alkyl Grignard reagents has been developed. Remarkably, the tertiary and secondary alkylation of gem-difluoroalkenes proceeded very smoothly in the presence of 25 mol % of CuCN or under transition-metal-free conditions, affording the tertiary and secondary alkyl-substituted fluoroalkenes in good to excellent yields with excellent Z stereoselectivity.

Silver-Mediated anti-Markovnikov and Markovnikov-Selective Hydrotrifluoromethylthiolation of Terminal Alkynes.

The first example of direct hydrotrifluoromethylthiolation of terminal alkynes in the presence of AgSCF3 and K2S2O8 was established for the synthesis of a variety of vinyl trifluoromethyl thioethers. The anti-Markovnikov and Markovnikov adducts were obtained in moderate to good yields via two different reaction systems. Studies to probe the mechanism of the anti-Markovnikov addition reactions including the radical trapping experiments, kinetic isotope effect experiments, and deuterated experiments for determination of H-sources were conducted.

Copper-Catalyzed Coupling Cyclization of gem-Difluoroalkenes with Activated Methylene Carbonyl Compounds: Facile Domino Access to Polysubstituted Furans.

A novel and efficient CuI-catalyzed synthesis of 2,3,5-trisubstituted furans was developed via coupling cyclization of gem-difluoroalkenes with active methylene carbonyl compounds such as 1,3-dicarbonyl compounds, acetoacetonitrile, and phenylsulfonylacetone with the assistance of a base. Commercial availability of substrates or reagents, good to high isolated yields, and excellent functional group compatibility make this transformation a powerful tool for the synthesis of various furans. A plausible mechanism involving the allenyl ketone is suggested.

Palladium- and nickel-catalyzed Kumada cross-coupling reactions of gem-difluoroalkenes and monofluoroalkenes with Grignard reagents.

A novel Kumada-Tamao-Corriu cross-coupling reaction of gem-di- or monofluoroalkenes with Grignard reagents, with or without β-hydrogen atoms, in the presence of a catalytic amount of palladium- or nickel-based catalysts has been developed. The reaction is performed under mild conditions (room temperature or reflux in diethyl ether for 1-2 h) and leads to di-cross- or mono-cross-coupled products in good to high yields.

Copper-free direct C-H trifluoromethylation of acetanilides with sodium trifluoromethanesulfinate.

A copper-free direct C-H ortho trifluoromethylation of electron-deficient 4-substituted acetanilides using Langlois reagent (NaSO2CF3) as the CF3 source in the presence of tert-butyl hydroperoxide (tBuOOH, TBHP) was developed.