Visible Light Induced Functionalization Of Tertiary Amine Dual C(sp~3)-H Bond Via Carbene Migratory

C-H bond is one of the most common chemical bonds in organic compounds.Many organic synthesis often need to generate new chemical bonds through the activation of specific C-H bond to synthesize the structure of functional target products.The activation strategy of C-H bond is simple and efficient,which shortens the steps needed for synthesis,and the reaction has excellent atomic economy and meets the requirements of green chemistry.It is of great value in the synthesis and modification of natural products and drug molecules to construct new chemical bonds by functionalization of C-H bonds directly.Carbene,as an unusual intermediate,has attracted great interest in the insertion reaction of C-H bond.Although various carbenes have been studied in detail,how to change the reactivity of carbenes while maintaining the hydrocarbon insertion reactivity is still a challenge for the efficient utilization and economic transformation of atoms.Visible light is a common light source for carbene release from diazo compounds.It has been widely used in organic synthesis because of its advantages of low cost,easy access,clean and safety.Among them,visible light induced electron transfer is one of the effective ways to realize the direct functionalization of C-H bond.In this paper,a visible light induced"one-step"reaction between o-chlorobenzaldehyde oxime and tertiary amines was developed to construct polysubstituted isoxazoles.Starting from the readily available raw materials o-chlorobenzaldehyde oxime(1)and tertiary amine(2),ethyl diazonium ester was induced to form free carbene through diazonium salt by visible light.The bifunction was realized by the transfer of carbene to the?,?-C_(sp3)-H bonds of saturated tertiary amine,and then formed in alkaline condition with o-chlorobenzaldehyde oxime 1,3-dipoles undergo[2+3]cycloaddition reaction to synthesize a group of substituted isoxazoles(3).In this reaction,CH₂Cl₂ was used as solvent,which was induced by visible light,alkali and room temperature.In one step reaction,the functionalization of two C_(sp3)-H bonds of tertiary amine?,?-position was functionalized at the same time,and the cyclized products were constructed.This reaction has excellent atomic economy,which provides a new way to explore carbene transfer and functionalization of C(sp³)-H bond.(?)...