Nucleophilic 5-endo-trig cyclisation of 2,2-difluorohomoallylic alcohols was achieved via allylic sp3 C–F bond activation to afford 3-fluoro-2,5-dihydrofurans.

The synthesis of trifluoromethylthiolated ketenimines is herein described. They are easily synthesized from the corresponding a-trifluoromethylthiolated oximes upon activationw ith triflic anhydride and ab ase. The presumed nitriliumi on resulting from the Beckmann rearrangement is deprotonated to lead to the key intermediate, whose stabilityb rought by the fluorinated substituent was unforeseeable. The reaction of these new building blocks with av ariety of nucleophiles affords av ast array of cyclic and acyclic productsb earing the valuable SCF 3 moiety.

Transition-metal-free acid-promoted biaryl construction was achieved via intermolecular C–F/C–H cross-coupling. By treating 2-fluorobenzofurans with arenes in the presence of AlCl3, 2-arylbenzofurans were obtained. This protocol was successfully applied to the...

Ketones and imines bearing a 2-(trifluoromethyl)allylic moiety successfully underwent nucleophilic 5-endo-trig cyclization via their metal enolates and enamides. O-or N-Cyclization proceeded exclusively in each case to afford the corresponding five-membered heterocycles with both exo-difluoromethylene and exo-alkylidene units. On treatment with potassium hexamethyldisilazide (KHMDS) or lithium diisopropylamide (LDA), 2-(trifluoromethyl)allylic ketones or imines provided the corresponding tetrahydrofurans or pyrrolidines bearing a Zalkylidene group with perfect or substantial stereoselectivity, respectively.

Nickel-catalyzed reductive cross-coupling of allylic difluorides with aryl iodides was achieved via allylic CÀ F bond activation. Based on this protocol, a series of γ-arylated monofluoroalkenes were synthesized in moderate to high yields with high Z-selectivities. Mechanistic studies suggest that the CÀ I bonds of the aryl iodides and the CÀ F bonds of the allylic difluorides were cleaved via oxidative addition and β-fluorine elimination, respectively, where the oxidative addition of less reactive CÀ F bonds was avoided to permit their transformation.