Generation Of Sulfonyl Compounds From Sulfur Dioxide Via Radical Reactions

As an important synthetic intermediate,sulfonyl compounds are widely used in medicinal chemistry and pharmaceutical industry.Therefore,synthesis of sulfonyl compounds under green and efficient conditions has been a hot topic among organic scientists for decades.On the basis of the well-developed strategies of insertion of sulfur dioxide,this thesis mainly focuses on developing new synthetic methods for the generation of sulfonyl compounds via radical reactions.It is classified into the following two parts.Part Ⅰ:Under visible light-induced conditions,a three-component reaction of hydrazines,thioporide salt and DABCO·（SO₂）₂is developed.A series of sulfonylhydrazide derivatives are obtained with good yields.The reaction is realized by capturing sulfur dioxide with the free radicals produced by thiorium salt in situ.The applicability of the substrate scope is demonstrated.Additionally,the functional late-stage modification of several drugs is also achieved.Part Ⅱ:A three-component reaction ofα,β-unsaturatedcarbonyl compounds,Hantzsch esters,and DABCO·（SO₂）₂under visible light catalysis in the presence of chiral organocatalyst is demonstrated.The reaction realizes the chiral control during the reaction process through hydrogen bonding.In this transformation,a radical produced from Hantzsch ester captures sulfur dioxide leading to sulfonyl radical,which then reacts withα,β-unsaturated ketone.The final products are obtained with good yields and high enantioselectivity.