Synthesis Of Quaternary Arylphosphonium Salts And Tertiary Arylphosphine Oxides And Immobilization Of Cyclic ?-alkoxyphosphonium Salts

Quaternary arylphosphonium salts and tertiary arylphosphine oxides have been widely used in organic synthesis,material chemistry,and biomedicine.Cyclic?-alkoxy phosphonium salts can be applied in the synthesis of vinyl ethers and1,2-diarylethanones.On the synthesis and utilization of these phosphonium salts and phosphine oxides,this thesis is composed of the following three studies.The first is on the synthesis of quaternary arylphosphonium salts from tertiary phosphines and aryl bromides.It was found that triphenylphosphine and aryl bromides in refluxing phenol for 5-30 h affords aryltriphenylphosphonium bromides in 26-99%yields.This reaction can tolerate a variety of functional groups such as hydroxyl,hydroxymethyl and carboxyl,thus providing a facile access to functionalized aryltriphenylphosphonium bromides.Furthermore,this reaction does not require the transition metal catalyst and explosive starting material.Temperature is closed to the reported method using Ni(II)as catalyst.The formation of aryltriphenylphosphonium bromides is proposed to through a two-step addition-elimination mechanism.In which the elimination step being a fast step as indicated by the deuterium experiment.In the presence of catalytic Ni Br₂,methyldiphenylphosphine or benzyldiphenylphosphine with aryl bromides in refluxing phenol also produces the corresponding quaternary phosphonium salts in48-90%yields.This reaction can also tolerate a variety of functional groups,and in some cases does not require the transition-metal catalyst.The second is on the synthesis of tertiary phosphine oxides from quaternary arylphosphonium salts.It was found that the yield of aryldiphenylphosphine oxides synthesized from arylphosphonium salts by alkaline hydrolysis depends on reaction conditions and functional groups.For the hydrolysis in aqueous 3 M Na OH,the yields are very high when the aryl has electron-donating groups.When the aryl has functional groups such as OH,COOH,and Ac,it is necessary to use t-Bu OK as a base and stoichiometric water for obtaining the high yields.For the polyaromatic aryls,the aryls bearing an electron-withdrawing group at the para position,and some ortho-substituted aryls,aryldiphenylphosphine oxides could not be obtained in high yields by alkaline hydrolysis.These phosphine oxides can be synthesized by a two-step,quaternization-Wittig strategy:quaternization of methyldiphenylphosphine or benzyldiphenylphosphine with aryl bromides produces the corresponding phosphonium salts,which are then subjected to the Wittig reaction with an aldehyde to provide aryldiphenylphosphine oxides in 27-90%yields.This strategy utilizes the Wittig reaction in a way that the phosphine oxide is the desired product while the olefin is the undesired product,in contrast to the traditional use of the Wittig reaction in which the olefin is the desired product while the phosphine oxide is the undesired product.The third is on immobilization of cyclic?-alkoxyphosphonium salts.Alkaline hydrolysisof(4-hydroxy-2-(hydroxymethyl)phenyl)triphenylphosphonium bromides followed by reduction with Me(Et O)₂Si H afforded4-(diphenylphosphino)-3-(hydroxymethyl)phenol,which was then subjected to aromatic nucleophilic substitution with 2,3,4,5,6-pentafluorostyrene to give(2,3,5,6)-tetrafluorostyrene monomer linked with a moiety of(2-diphenylphosphino)benzenemethanol.This monomer copolymerized with1,4-divinylbenzene followed by reaction with methyl 4-formylbenzoate or2-formylbenzonitrile provides two immobilized cyclic alkoxyphosphonium salts,which were preliminarily tried for the corresponding Wittig reaction followed by hydrolysis to afford the corresponding 1,2-diarylethanones.