Electrochemical Radical Formyloxylation–bromination, –Chlorination, And –Trifluoromethylation Of Alkenes

Given the versatile and value of the structurally diverse Organohalorides and CF₃-containing compounds in organic synthesis,we have developed a versatile and environmentally friendly method for electrochemical anodic oxidative radical bromination,chlorination and trifluoromethylation-formyloxylation of the alkenes with readily available halogen radical?NaCl,NaBr?,trifluoromethyl radical?CF₃SO₂Na?sources and DMF as formyloxylation reagents.The protocol is operationally simple and avoiding the use of exogenous stoichiometric chemical oxidants and exhibiting a broad substrate scope for difunctionalization of various alkenes.Preliminary mechanistic studies revealed that the Cl^-,Br^-,CF₃^-was oxidized at the anode to generate Cl,Br,CF₃ radical.1.Electrochemical anodic oxidation radical bromination,chlorination-formyloxylation of alkenesWe developed a green,oxidant-free electrochemical method using undivided electrochemical cells equipped with a carbon anode and a platinum cathode for radical bromination,chlorination of the various alkenes with readily available halogen radical?NaCl,NaBr?sources and DMF as formyloxylation reagents.Finally,we finished the electrochemical anodic oxidation radical bromination-formyloxylation of alkenes under constant current electrolysis at 3.0 mA in the presence of HCOOH?1.5 mL?as the sacrificial oxidant and n-Bu₄NPF₆?2.0 equiv?as the electrolyte in DMF?4.0 mL?at room temperature for 24 h.Gratifyingly,we finished the electrochemical anodic oxidation radical chlorination-formyloxylation of alkenes under constant current electrolysis at 3.0 mA in the presence of HCOOH+H₂O?0.5+0.1 mL?,n-Bu₄NPF₆?2.0 equiv?,CuCl?10 mmol%?in DMF?4.0 mL?at room temperature.Preliminary mechanistic studies revealed that the Cl^-,Br^-was first oxidized at the anode to generate Cl,Br radical.Then,this Cl,Br radical rapidly combines with arylalkene,affording benzyl radical intermediate.The radical intermediate can be oxidized to benzyl carbocation which was subject to nucleophilic attack by DMF to give imine intermediate.Hydrolysising of imine intermediate afforded the desired halo-functionalization product as well as a hydrogen cation which was reduced at the cathode to release hydrogen gas.2.Electrochemic alanodic oxidation radical trifluoromethylation-formyloxylation of alkenesGiven the prevalence of CF₃ groups in pharmaceuticals,materials and agriculture chemicals,difunctionalization of unsaturated double bonds is considered as a useful protocol for the synthesis of diverse trifluoromethylated compounds which adjusts its bioactivity?chemical and metabolic stabilities,lipophilicity and binding selectivities?.we have developed a versatile and environmentally friendly method for electrochemical anodic oxidative radical trifluoromethylation-formyloxylation of the alkenes with readily available trifluoromethyl radical?CF₃SO₂Na?sources and DMF as formyloxylation reagents.Encouraged by the formyloxylation-bromination,chlorination of alkenes,we finished the trifluoromethylation-formyloxylation under constant current electrolysis at 3.0 mA in the presence of HOAc+H₂O?0.5+0.1 mL?,n-Bu₄NPF₆?2.0 equiv?,CuOAc?10 mmol%?in DMF?4.0 mL?at room temperature.Preliminary mechanistic studies revealed that the CF₃^-was first oxidized at the anode to generate CF₃ radical.