Construction Of Visible Light Induced C-P Bonds And Antifungal Activity Of Phosphorylated Derivatives

Agricultural and forestry resources are very important social resources.However,frequent plant diseases and insect pests make agricultural and forestry plants seriously threatened.Chemical pesticides play an important role in the prevention and control of agricultural and forestry diseases and insect pests,but they expose many problems such as pesticide residues,high toxicity and environmental harm.In the context of promoting sustainable development,the development of biopesticides is of great significance to reduce the negative effects of chemical pesticides and improve the ecological environment.Natural products from forest source have unique chemical structure,high selectivity and specific biological activity,and have been an important source of lead discovery of drug activity.Phosphorus compounds are widely used in insecticides,fungicides,herbicides,surfactants,and plasticizers.Secondly,after modification of phosphorus atoms,they can improve the lipophilicity and hydrophilicity of drug molecules,thus improving biological activity or drug delivery efficiency.However,there are very few reports on derivatives that combine the framework of forest-derived active natural products with the structure of diphenylphosphine oxide.Therefore,it is of great significance to construct and study the structure of diphenylphosphine oxide with the framework of forest-derived active natural products innovatively for the development of new biological pesticides.Efficient construction of organic phosphine compounds has always been a hot topic in the field of organic chemistry.Among them,there are three methods for C-P bond construction:transition metal catalyzed C-P bond coupling reaction,photocatalyzed C-P bond formation reaction and electrocatalyzed C-P bond formation reaction.The traditional phosphorus free radical is mainly derived from the oxidation of phosphorus hydrogen reagent.The development of novel phosphorus free radical formation strategy is an important supplement to the existing methods.This paper focuses on the efficient construction of C-P bond under visible light catalysis,and successfully develops a method with mild conditions,high functional group tolerance and good scalability,which has broad application prospects and potential economic value,and provides technical support for the greening of related reactions.This paper mainly includes the following aspects:（1）Tulip A and diphenyl ethoxyphosphine were selected as the model substrate,and the effects of different organic solvents,photosensitizers,reaction concentrations and the dosage of diphenyl ethoxyphosphine on the reaction yield were explored,and the optimal reaction conditions were finally determined.At the same time,the natural products and their derivatives with similar skeleton structure of tulip A can be used as substrates,and the derivatives containing diphenylphosphine oxide structure can be obtained with higher yield.Subsequently,studies on antifungal activities of these products showed that they had excellent antibacterial activities against agroforestry pathogenic fungi,especially terpenoids and phosphine acylation products.This reaction has the very good substrate universality,the substrate can be expanded to the heterocyclic and other electron-deficient olefins,such as thiazole,benzothiazole,benzene and oxazole anda,b-unsaturated ester and products through the nuclear magnetic resonance（NMR）and high resolution mass spectrometry（HRMS）identification.（2）A series of vinylpyridine substrates were prepared to study the C-P bond reaction between vinylpyridine compounds and diarylethoxyphosphine.Using 2-vinylpyridine and diphenyl ethoxyphosphine as model substrates,the effects of different organic solvents,photosensitizers,reaction concentrations and dosage of diphenyl ethoxyphosphine on the reaction yield were discussed,and the optimal reaction conditions were determined.This reaction has good substrate universality to vinylpyridine substrates,and the highest yield can reach 99%.In addition,different kinds of diarylethoxyphosphine are also suitable for this reaction.The products were identified by NMR and HRMS.The reaction mechanism has been reasonably speculated.In addition,the amplification experiment can be carried out smoothly.（3）The formation of C-P bonds between alkynes and diphenyl ethoxyphosphine has been studied.Phenylacetylene and diphenyl ethoxyphosphine were selected as the model substrate to explore the effects of different organic solvents,photosensitizers,reaction concentrations and the amount of substrate on the yield of the reaction.Finally,the optimal reaction conditions were determined:The solvent was acetonitrile,the photosensitizer was[Ir（d F（CF₃）ppy）₂（dtbbpy）]PF₆,the reaction temperature was room temperature,the reaction concentration was 0.03 M,and the dosage of phenylacetylene was 3.0 equivalent.This reaction shows excellent substrate universality to alkynes,with a maximum yield of 80%.Symmetrical internal alkynes can be converted to target compounds at moderate yields,and complete control of regional selectivity has been observed with asymmetric alkynes.The products were identified by NMR and HRMS.