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

ABSTRACT

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.