Radical Reactions In Aqueous Phase:Synthesis Of Sulfonamides And Aryl Methyl Sulfones

Sulfonamides,?-arylsulfonyl enamines and aryl methyl sulfones not only can be used as intermediates in organic synthesis,but also have good biological activities.Therefore,these compounds have very important applications in the fields of organic synthesis and medicines.The radical reaction plays an important role in the development of modern organic synthesis.To date,most of the radical reactions were carried out in unfriendly organic solvents,usually by using precious and/or toxic catalysts and additives.Thus,it is important to develop an efficient and green method for the radical reactions in H2 O solvent to synthesize sulfonamides and aryl methyl sulfones.In this paper,we mainly focused on radical reactions in H2 O solvent for the synthesis of sulfonamides,?-arylsulfonyl enamines and aryl methyl sulfones.(1)I2/TBHP mediated synthesis of sulfonamides,?-arylsulfonyl enamines from sodium sulfinate salts and tertiary amines.The effects on reaction about the amount of iodine and tert butyl alcohol,reaction temperatures and different solvents were systematically studied.The target products were characterized by GC-MS,HR-MS,1H NMR and 13 C NMR.The experimental results revealed that H2 O as the solvent resulted in the C-N bond cleavage of tertiary amines to produce sulfonamides due to H2 O participating in the reaction process where H2 O plays a dual role.Differing from H2 O,dimethyl sulfoxide(DMSO)could promote the C-H bond cleavage of tertiary amines to yield ?-arylsulfonyl enamines.The solven in the present system plays a very important role in the formation of sulfonamides or ?-arylsulfonyl enamine.In addition,the prelimary research of the reaction mechanism shows that the formation of sulfonamides or ?-arylsulfonyl enamines presumably undergoes a radical pathway.The present work provides a novel and efficient method for the synthesis of sulfonamide and ?-arylsulfonyl enamines.(2)The reaction between sodium sulfinates and di-tert-butyl peroxide could generate aryl methyl sulfones in good to excellent yields in H2 O medium under heating conditions by the coupling reaction.The results show that the reaction undergoes a radical pathway in the aqueous phase.Di-tert-butyl peroxide is split into tert-butoxyl radical by O-O bond cleavage under heating conditions.Next,the tert-butoxyl radical further decomposes to a methyl radical and acetone at 110 ?C.At the same time,the reaction of the tert-butoxyl radical with a sulfinate anion generates a sulfonyl radical.Finally,the sulfonyl radical reacts with the methyl radical to give the target product aryl methyl sulfones.This investigation provides a novel and green method for the synthesis of aryl methyl sulfones.