Synthesis Of β,β-Dicholoro-α,β-Unsaturated Ketones By Enol Silyl Ether And Enol Acetate In Series Elimination Reaction With Trichloromethyl Radical Addition

Radical reaction has the advantages of fast rate,mild conditions,and good tolerance of functional groups,etc.It is a powerful method to efficiently construct complex organic compounds,so it has received widespread attention in the field of organic synthesis.Enol silyl ether and enol acetate have an electron-rich double bond and have good reactivity with electrophilic reagents or free radicals.It is equivalent to ketone analogs and occupies an important position in organic synthesis.The α,β-unsaturated carbonyl skeleton can be used to construct a variety of useful compounds through regio-or stereoselective chemical transformations.At the same time,β,β-dichloro-α,β-unsaturated ketones add more possibilities in the conversion due to the presence of chlorine atoms at the β position.Based on the widespread application of α,β-unsaturated carbonyl compounds,it is very important to continuously develop new effective methods for the synthesis of α,β-unsaturated carbonyl compounds.In this dissertation,through the strategy of enol silyl ether or enol acetate in series trichloromethyl radical addition with elimination reaction carried out in the following two aspects:1)Enol silyl ether derived from aryl ketone in series trichloromethyl radical addition with elimination reaction was studied.Using chloroform or carbon tetrachloride as the trichloromethyl radical source and the reaction solvent,a series of 21 β,β-dichloro-α,β-unsaturated ketone compounds were synthesized by enol silyl ether in series trichloromethyl radical addition with elimination reaction,the highest yield of the product can reach 91%.The reaction uses DTBP as an oxidant,no metal catalysis is needed,raw materials are easily available,and the conditions are mild.The enol silyl ether substrate has good universality.The results show that both chloroform and carbon tetrachloride are good reagents.When carbon tetrachloride is trichloromethyl radical source,the yield is higher than that of chloroform.At the same time,the additive base plays a key role Role in the reaction.Since enol silyl ether is unstable to water,it is very important to remove water from the reaction system.2)Enol acetate derived from aryl ketone in series trichloromethyl radical addition with elimination reaction was studied.Using DTBP as oxidant,chloroform or carbon tetrachloride as trichloromethyl radical source and reaction solvent,the enol acetate derived from aryl ketone in series radical addition reaction with elimination reaction to synthesize 16 series of β,β-dichloro-α,β-unsaturated ketone compounds.The reaction is catalyzed by cheap metal copper,with mild conditions and simple operation,and the highest yield of the product can reach 90%.Compared to enol silyl ether,enol acetate is more readily available and stable.