Synthesis And Application Of ?-C₂-Bridged Biphospholes

Phosphole plays an important role in exploring the phosphorus chemistry research.What's more,it is widely applied in coordination chemistry,catalysis and organic photoelectric materials and other fields.[1,5]-sigmatropic shift(hereinafter referred to as [1,5] shift)is an important reaction of phospholes.As a result of the pyramidal geometry of phosphorus,the [1,5]-sigmatropic shift of the phosphorus substituent from P to C as a result of the significant ?-?* overlap between the exocyclic P-R bond and the dienic system.The ease with which [1,5] shifts occur as a function of the nature of the migrating group.Whereas hydrogen migrates very easily even below room temperature when no substituent is present on the R-positions of the ring.Other groups,such as aryl(Csp2),miscellaneous aryl(Csp2),alkynyl(Csp)and carbonyl(Csp2)and CN(Csp),etc,require the application of heat,while some others do not migrate under conditions compatible with the intrinsic stability of the phosphole ring(alkyl,OR,etc.).2H-Phosphole is a tautomer of parent 1H-phosphole.As already dicovered,based on their conjugated P=C and C=C double bonds,2H-phospholes can act as powerful dienes and react with some unsaturated compounds.A very recent cycloaddition reaction of this type is 2H-phosphole's [4+2]cycloaddition with the C=O bonds of aldehydes.They can also act as dienophiles toward conjugated dienes via their P=C double bond.In The first chapter we introduced the synthesis of phosphole and(phospha)fulvene.Moreover,the cycloaddition reaction of phosphole,2H-phosphole and phosphafulvene were reviewed.Partuculary,we discussed the the influence factors on the reaction manner of fulvene's cycloaddition reactionThe second chapter mainly report synthesis of a series of novel ?-C2-bridged biphospholes by the reaction of 3,4-dimethyl-1-aromatic phosphole and imine under the catalysis of mild lewis acid.We explored the optimum reaction conditions,the substrate suitability and the mechanism of the reaction,the mechanism preliminary revealed the reaction includes a series of [1,5] shifts of the substituents around the phosphole ring,the nucleophilic addition of P-H to imines' C=N and a firstly reportedsp3 carbon [1,5]-sigmatropic shift of phospholes.Moreover,the separation of an important intermediate proved this mechanism.Asymmetric products also obtained from this route.The synthetic route was optimized further and became more simplification and convenience.At last,we investigated the reactions of biphophole anions prepared by the reaction of alkali metal(Li,Na)and ?-C2-bridge biphospholes(THF solution).We prepared a diphosphaferroceneophane by Fe Cl2 and biphospholide.The ready availability of biphospholes offer a lot of synthetic possibilities using the chemistry of the P-P bond.What's more,these biphosphole anions can be used as source of bidentate ligand(contain P-M-P bonds).Besides,they can be used to synthesis a series of novel heterocyclic compounds with P-C-P and P-P-P structure by the reaction of biphospholide and electrophilic reagents(Ethyl propiolate,Me I,Ph PCl2 CH2 Cl CH2Cl and so on).In the third chapter we mainly introduced the application of ?-C2-bridge biphospholes that we prepared in our previous work,which is some firstly reported caycloaddition reaction of 1-phosphafulvenes.We discovered 1-phosphafulvenes by reaction of intermediate 3-1 and 2,3-dimethyl-1,3-butadiene and proved its sability by theoretical calculation 1-phosphafulvenes' reaction with 2-phenyl-phosphole could be interpreted as a [6+4] cycloaddition reaction.Furthernore,we inferred1-phosphafulvene can be generated by dissociation of ?-C2-bridge biphospholes and proved it by mixed reaction of two different ?-C2-bridge biphospholes,on which our research was based.Our research revealed that as electron-rich partners,they act as 4? phosphadienic systems toward alkenes and alkynes in [4+2] cycloaddition reactions.As electron-poor partners,they act either as 2? systems via their P=C double bond toward conjugated dienes in [2+4] cycloaddition reactions or 6 ?systems toward phosphadienes in [6+4] cycloaddition reactions.Overall,their reactivity is quite similar to that of fulvenes and their P-lone pair is silent in cycloaddition chemistry.