Studies On The Method Of P(O)–OH And Sp~3C–H Compounds Dehydrogenation Cross-coupling To Synthesis Organophosphate Esters

The generation of organic phosphate esters is of great importance in synthetic chemistry because these kinds of compounds are found in numerous biological,pharmaceutical,and material substances.Traditional procedures for their synthesis usually directly or indirectly depended on the transformation of the highly toxic and water-sensitive organohalides.These reactions usually suffer from hazardous conditions and low co-presence of functional groups.At present,the sp~3 C–H bond dehydrogenation cross-coupling reaction can avoid complicated experimental operations and pretreatment and use experimental materials effectively.The method is environmentally friendly and has been widely applied and reported in the synthesis of organophosphates.However,many researchers focuse on the use of water-and air-sensitive P(O)–H reagents as a raw material.Compared with P(O)–H reagents,P(O)–OH reagents are more stable and cheaper.Hence,the development of an efficient and green method that is diversely substrate-tolerant for the synthesis of organophosphorus compounds via oxidative sp~3 C–H/P(O)–OH cross dehydrogenative coupling is highly desired.The research contents of this paper:the synthesis method of oxidative dehydrogenation coupling to prepare organic phosphates was studied by using P(O)–OH compounds as raw material via activating methyl/methylene sp~3 C–H bonds.The research work enriches the preparation method of organic phosphates.The proposed research strategy has a wide of substrate scope and giving the corresponding products in good yields.Based on a series of control experiments,the possible reaction mechanisms were explored.The main research contents and innovations are summarized as follows:(1)The synthesis method of organophosphates by dehydrogenation and cross-coupling of methyl arene benzyl sp~3 C–H bonds and P(O)–OH compounds was studied via using cetyltrimethylammonium bromide as catalyst.The method overcomes the shortage of the phosphorus reagent in the traditional synthetic method,such as being difficult to store,expensive,and easy to pollute the environment.The substrate dialkyl phosphates are also suitable for the method,and the target product yields can reach about 80%,which expands the application range of the substrate.Through a series of control experiments,the plausible mechanism of the reaction was explored.(2)The method for the preparation of organophosphates by dehydrogenation cross-coupling of cyclic alkanes inert sp~3 C–H bond with diphenylphosphoric acid was studied via using cheap copper powder as catalyst.The catalytic system is simple in operation,environmentally friendly,and has a wide range of substrates.It provides a new strategy for the activation of cyclic alkanes inert sp~3 C–H bonds.