Study On Ruthenium Catalyzed N=P Double Bond Formation By Visible Light

As an analog of phosphine ylide,phosphazenes have a wide range of applications in organic synthesis,biology,medicine,and polymers.The traditional methods for synthesizing phosphazene compounds are Staudinger reaction and Kirsanov reaction.However,these two methods have the disadvantages of complicated steps,harsh reaction conditions and high raw material cost.Therefore,it is of great significance to develop a simple and economical new method for synthesizing a phosphazene compound.The visible light-induced catalytic reaction has the advantages of green,safety,high efficiency,mildness,and has its advantages in the construction of chemical bonds.In this paper,under the condition of visible light irradiation,ruthenium-catalyzed reactions of 1,4,2-dioxazole-5-ketone compounds with triaryl phosphorus were carried out to synthesize phosphazene compounds,and the safe and efficient synthesis of these compounds was realized.The reaction of 3-phenyl-1,4,2-dioxazol-5-one with triphenylphosphine was used as a template to determine the optimal reaction by examining the catalyst,solvent,reaction time and other conditions.The optimal reaction conditions were as follows:Ru₂?p-cymene?₂Cl₄ as catalyst?1 mol%?,1,4-dioxane as reaction solvent?2 mL?,12 W blue LED lamp was used as the light source and reacted for 1 h under N₂ protection.An N-?triphenyl-?⁵-phosphoramidino?benzamide compound was produced in 98%yield under optimal reaction conditions.It has been found that both aromatic,heteroaromatic and aliphatic oxazolone compounds were tolerated.Both the pull-electron group and pull-electron group on substituted aromatic hydrocarbons could obtain the target products with high yield.The steric hindrance effect on the substituted aromatic hydrocarbons had an effect on the reaction yield.On the other hand,the aromatic ring of triphenyl phosphorous compounds contains fluorine,chlorine,methyl and N,N-dimethyl could also obtain corresponding phosphorous azenes with high yield.The obtained phosphazene compounds were characterized by ¹H-NMR,¹³C-NMR and ³¹P-NMR.