Electrochemical Oxidative Pyrazolinone C-S Bonding Reaction And Hydrazone C-S Bonding Reaction

Traditional C-H functionalization reactions are usually carried out at high temperatures and rely on a variety of metal catalysts and external oxidants,which have low atomic utilization and can produce chemical pollution.In recent years,in organic synthesis,electrochemical catalytic oxidation coupling has become a popular method to activate carbon.Electrochemical catalysis can produce oxidation reaction and reduction reaction on the electrode respectively,which can avoid the use of additional oxidant and reducing agent and then the next reaction can occur.Therefore,electrochemical catalysis synthesis technology is considered to be one of the most environmentally friendly synthesis technologies.Over the past decade,organic electrosynthesis has become a method of synthing a series of complex molecules In addition,the by-product of electrochemical catalysis is generally hydrogen,which has the advantages of high efficiency,green and controllable.So electrochemical catalysis synthesis has become a very practical and valuable method of organic synthesis.In this paper,the reaction of the carbon-sulfur bond formed after the carbon-hydrogen bond was attacked by electrochemical oxidation activation of sulfur groups and 3-methyl-1-phenyl-2-pyrazoline-5-ketone reacts with ammonium thiocyanate in the presence of external oxidant,external electrolyte and inorganic catalyst to produce multi-purpose ammonium oxide by using electrochemical method,and C-S bond reaction with cross-coupling of sodium sulfite and hydrazone by electrochemical oxidation relevant research has mainly obtained the following results:1.Oxidative cross coupling of 2,5-substituted pyrazoline-5-ketone with ammonium thiocyanate was successfully realized in the absence of external oxidant,external electrolyte and inorganic catalyst,and a series of unprecedented cross coupling products were obtained.It is worth noting that since the resulting cross-coupling product is almost insoluble in Me CN,the pure product can be obtained by direct pumping and filtration without the need for purification by silica gel column.In addition,the prepared ammonium oxide is the basic material for the synthesis of functionalized pyrazole derivatives2.Electrochemical oxidation of C(sp~2)-H sulfonylation of hydrazone without metal catalyst and external oxidant has been achieved for the first time.All kinds of designed sodium sulfonite can well produce sulfonyl radical and attack C(sp~2)-H reaction of hydrazone with moderate to good yield.Satisfactory yield can also be obtained by gram-scale reaction,which opens up the possibility for practical application.