Ligand‐Controlled, Tunable Copper‐Catalyzed Radical Divergent Trifluoromethylation of Unactivated Cycloalkenes

Synthesis of fluorinated spiro-1,3-oxazines and thiazines via Selectfluor-mediated intramolecular cyclization

A fluorination-induced intramolecular cyclization for the synthesis of fluoro-substituted spiro-1,3-oxazine and spiro-1,3-thiazine derivatives is described. N-(2-(Cyclohex-1-en-1-yl)ethyl)benzamide and benzothioamide are used as the substrates, and the cationic fluorinating agent Selectfluor works as the fluoride source. The reaction yields a single diastereomer. The scope of this regioselective fluorination reaction is established by preparing thirty different spirooxazine and spirothiazine derivatives.

Ligand-Controlled Copper-Catalyzed Halo-Halodifluoromethylation of Alkenes and Alkynes Using Fluorinated Carboxylic Anhydrides

Polyhalogenated molecules are often found as bioactive compounds in nature and are used as synthetic building blocks. Fluoroalkyl compounds hold promise for the development of novel pharmaceuticals and agrochemicals, as the introduction of fluoroalkyl groups is known to improve lipophilicity, membrane permeability, and metabolic stability. Three-component 1,2-halo-halodifluoromethylation reactions of alkenes are useful for their synthesis. However, general methods enabling the introduction of halodifluoromethyl (CF2X) and halogen (X') groups in the desired combination of X and X' are lacking. To address this gap, for the first time, we report a three-component halo-halodifluoromethylation of alkenes and alkynes using combinations of commercially available fluorinated carboxylic anhydrides ((CF2XCO)2O, X=Cl and Br) and alkali metal halides (X'=Cl and Br). In situ prepared fluorinated diacyl peroxides were identified as important intermediates, and the use of appropriate bipyridyl-based ligands and a copper catalyst was essential for achieving high product selectivity. The synthetic utility of the polyhalogenated products was demonstrated by exploiting differences in the reactivities of their C-X and C-X' bonds to achieve selective derivatization. Finally, the reaction mechanism and ligand effect were investigated using experimental and theoretical methods to provide important insights for the further development of catalytic reactions.

Metal-free electrochemistry promoted radical cascade cyclization to access CF3-containing benzimidazo[2,1-a]isoquinolin-6(5H)-ones

Using CF3SO2Na as the CF3 radical source, an eco-friendly approach for electrochemistry-mediated radical cascade cyclization of N-methacryloyl-2-phenylbenzoimidazoles was described. This reaction features mild reaction conditions, readily available substrates, and moderate to good yields through the construction of two C-C bonds in one step.

CuCl2 -Catalyzed α-Chloroketonation of Aromatic Alkenes via Visible-Light-Induced LMCT

Here we report a copper-catalyzed protocol for the synthesis of α-chloroketones from aromatic alkenes including electron-deficient olefins under visible-light irradiation. Preliminary mechanistic studies show that the peroxo Cu(II) species is the key intermediate and hydroperoxyl (HOO⋅) and chlorine (Cl⋅) radicals can be generated by ligand-to-metal charge transfer (LMCT).

Recent Advances in Transition-Metal Mediated Trifluoromethylation Reactions

Fluorine compounds are known for their abundance in more than 20% of pharmaceutical and agrochemical products mainly due to the enhanced lipophilicity, metabolic stability and pharmacokinetic properties of organofluorides. Consequently,...