The Green Synthesis Of Aromatic Alcohol Under Electrochemical Conditions

Aryl alcohols are widely used in spices and cosmetics.Additionally,aryl alcohols are also the key intermediates for functional molecule and drug syntheses.Thus,the green synthesis of aryl alcohols has attracted great attention.Classical methods for aryl alcohol synthesis involve the addition of organometallic reagents to aldehydes or ketones.However,the use of organometallic reagents resultes in poor functional group compatibility.The reductive arylation of carbonyl compounds provides an alternative for the construction of aryl alcohols.However,the use of expensive photoredox catalysts or excess amount of metal reductants in combination with transition metal catalysts limits its wide application.In line with our previous research on electrosynthesis,this thesis herein reports a new method for electrochemical arylation of aldehydes,ketones and alcohols,which can compound secondary and tertiary aryl alcohols efficiently by using aldehydes,ketones or alcohols as starting materials in the absence of external redox reagents and transition metal catalysts.Compared with previous reports on aryl alcohol synthesis,this method has the advantages of mild reaction conditions,high atomic utilization,less emission of three wastes and high synthesis efficiency.This thesis includes the following two parts:(1)The first part examines the electroconductive arylation of aldehydes or ketones with electron-deficient aryl nitriles.This is carried out in an undivided cell,in which the graphite is as the anode,nickel as the cathode,DMSO as the solvent,n-Bu4NOAc as the electrolyte,and valeral as the additive,and the yield of the reaction is up to 99%;valeraldehyde,as an additive,can effectively remove the cyanide anion generated by the reaction and improve the yield of the reaction.By taking advantage of the mild conditions,this reaction shows broad functional group compatibility.In particular,some labile functional groups,including ester(OAc),amide(NHAc),amine(NMe2),thioether(SMe),and borate ester(BPin)which are poorly-tolerated under conventional approaches,remain unaffected under the electrochemical conditions.Then,the yield of the reaction can still be maintained at 94%when the reaction scale is expanded to gram scale,which demonstrates the synthetic utility of the method.(2)Encouraged by the success of arylation of carbonyl compounds under electroconductive conditions,this thesis continues the electrochemical arylation of alcohol.After changing the reaction conditions,this thesis firstly realizes the coupled reaction of benzyl alcohol derivatives and electron deficient aryl nitriles by using convergent paired electrosynthesis,which provides a green and efficient way for the transformation of low-value alcohols into more useful alcohols.This way features mild reaction conditions,has a high atomic economy,shows excellent functional group tolerance,and can be easily scaled up to gram scale.