Carbon-Oxygen(Sulfur) Bond Formation Reaction Based On Free Radical Reaction History

Carbon-oxygen（sulfur）linkages are widely present in many natural products,drugs and polymers.A number of compounds containing C-O（S）bonds are often used as intermediates in pharmaceuticals due to their high medicinal activities,such as antibacterial and anti-HIV activities.In organic synthesis,sveral methods for forming a C-O（S）bond has been well established,such as ion reaction,radical reaction,and some others.However,most of these reported reactions usually require precious metal catalysts,ligands,or high temperatures.Therefore,the development of mild and economical methodology for generating C-O（S）bonds is of interest.Based on the understanding of the C-O（S）bond formation,we will start the research concerning the constrction of C-O（S）by using cheap metal catalysis and visible light catalysis instead of traditional precious metals catalysis,which are listed as follows:（1）The acetoxylation of 2H-azirines with hypervalent iodine（III）reagents by using Fe（acac）₂ as catalyst could proceed in anhydrous toluene at 70°C for 7 hours,generating a number of oxidation products in moderate to good yields.It should be noted that three-membered ring structure are not affected in this catalytic system,which provides a novel method for the selective oxidation of 2H-azirines.（2）Under blue light（450–455 nm）irradiation,the selective addition reaction of（E）-1-phenylbut-3-en-1-one oxime with sulfonyl hydrazide occurred in the presence of Na₂-eosin Y as a photocatalyst,silver oxide as an oxidant,acetonitrile as a reaction medium,producing the linear organic sulfone in good yields.Mechanistic studies demonstrate an intramolecular 1.5-hydrogen migration may be involved in the catalytic cycle through DFT caculations.