Electrochemically Sulfonylation-Induced Lactonization Of Alkenes

Organic compounds are closely related to industrial production,medical and health in daily life,and they have brought many benefits to the progress of human society.However,the synthesis and production of organic substances often involve the use of hazardous chemicals and the control of harsh reaction conditions,which pose a certain threat to safe production and the environment.Therefore,the development of environmentally friendly organic synthesis methods has always been one of the significant problems faced by chemists.Electrochemical organic synthesis refers to the realization of efficient conversion and controllable synthesis of organic molecules at the electrode interface by designing a reasonable electrode interface and controlling voltage or current.In recent years,electrochemical organic synthesis has gradually developed into an effective green synthesis method due to its high reaction selectivity,simple operation process and less environmental pollution.Phthalides are significant organic skeletons with a variety of medicinal values that are commonly found in chemical materials,pharmaceutical active molecules and natural products.Studies have shown that introduction of sulfonyl fragments into drug molecules can not only significantly enhance its pharmacological activity but also make it undergo a great diversity of organic transformations.Thus,various synthetic methods of sulfonyl phthalides were reported.However,most of these works involved the use of expensive and toxic catalysts or chemical redox agents,which was extremely unfavorable to personal safety,environmental protection and large-scale industrial applications.In order to overcome these problems,we first developed a green and environmentally friendly method for olefin lactonization induced by electrochemical sulfonylation with graphite plates as electrodes,o-vinylbenzoic acids and sulfonyl hydrazines as starting materials,CH₃CN/H₂O（4 m L,10/1,v/v）as reaction solvent,Li Cl O₄ as electrolyte and acetic acid as additive in this paper.The reaction was conducted under mild electrochemical oxidation conditions and the correspondingγ-sulfonyl phthalides were achieved with broad substrate tolerance in good yields.Moreover,heating,pressurization,catalysts,and stoichiometric redox agents were not required during the reaction process.Finally,the excellent yield shown by the gram-scale experiment indicated that this electrochemical method has potential practical applications.