Studies On Chemistry Of Ortho-(Isocyanide/Nitrile)tertiary Phosphines

Contrary to the intensive investigation of phospholes,the chemistry of tertiaryl phosphines' cleavage of P-C bond remained undeveloped.Hence,we designed and synthesized ortho-(isocyanide/nitrile)tertiary phosphines to use the result as a starting point in this dissertation.After the reaserch on the chemistry of these species,several new and intramolecular cyclization reactions were discovered,especially developing the methods for preparation of 1,2-and 1,3-azaphospholes and ?5-phosphinines and their derivatives.The dissertation consists of four chapters as follows:In the first chapter,it demonstrates the electronic structure of 1,3-and 1,2-azaphospholes,and also summarizes the synthetic methods,chemical properties and applications of 1,3-and 1,2-azaphospholes and their derivatives.In the second chapter,we describe the versatile chemsitry of easily made ortho-(diarylphosphino)aryl isocyanides.The electronic structure of isocyanides determine their rich synthetic chemistry and versatile coordination chemistry.According to the reported literatures,ortho-(diarylphosphino)aryl isocyanides are still new compounds.We developed an efficient route to synthesized 1,3-azaphospholides by breaking of the P-C bonds.A preliminary study of the reactivity of these new species was undertaken.Treating 2 with benzyl bromide or methyl iodide and sulfur gave 3H-1,3-benzazaphosphole sulfides 3.Quenching the reaction mixture with water led to 1H-1,3-benzazaphospholes 4.Phosphines 1 can also serve to prepare the 6-membered?5-1,4-benzazaphosphinines by attacks of intramolecular ylide on isocyanide group.Besides,we also studied the coordination chemistry of ortho-(diarylphosphino)aryl isocyanides.The reaction of phosphine-isocyanide with a gold chloride complex expectedly affords bis-complex 7 in which both functionalities are coordinated.The course of the reaction with palladium chloride is quite different,giving a rare Pd-carbene complex 8.Very unexpectedly,annelated benzazaphosphinine 9 was obtained by the reaction with nickel chloride.From all of the preceding experiments,the chemsitry of ortho-(diarylphosphino)aryl isocyanides is diverse and unpredictable.More chemistrycan be envisaged.In the third chapter,we describe a novel and versatile route for the conversion of ortho-(diphenylphosphino)phenyl nitriles into 1,2-azaphosphindoles.Treatment of phosphine-nitriles with an excess of lithium gives 1,2-azaphosphindolides(31P NMR165 ppm),which can react with RX(benzyl bromide,1-bromopropane and1,2-dibromoethane)and sulfur to form 2H-1,2-azaphosphindole sulfides 11.The azaphosphindolides 10 can be protonated at N to give1H-1,2-azaphosphindoles 12 by DFT computations.The azaphosphindole rings are strictly planar,and the shape of the HOMO shows that 12 can be legitimately considered as a 10? aromatic system.Treating 1,2-azaphosphindolides 10 with water gave 1H-1,2-azaphosphindoles 12(31P MNR 157 ppm).But reactivity of these species precluded their isolation.We trapped 12 by reaction with N-phenylmaleimide and sulfur.The target compound has been characterized by X-ray crystal structure analysis.The fourth chapter reports a very simple one-step synthesis of annelated?5-phosphanaphthalenes.As a result of their extrordinary efficience as liginds in the metal-catalyzed hydroformylation of olefins,and their great potential for applications in organic functional materials,?3?2-phosphinines have long been regarded as "chemical curiosities".Contrary to the quick development and intensive investigation of ?3-phosphinines,the chemistry of ?5-phosphinines and their derivatives remained undeveloped.The synthetic methods of ?5-phosphinines have also great limitations.Nucleophilic attacks of the phosphorus atom on electron-?deficient alkynes create reactive zwitterionic carbenoid species,which emerged as versatile intermediates for various transformations.Hence,we investigated the reactions of ortho-phosphino-benzonitriles with dimethyl acetylenedicarboxylate(DMAD).In doing so,a new approach to annelated ? 5-phosphanaphthalenes 14 was discovered.This method(17 exampples)is simple and atom-and step-effective.It is interesting to note that all the solutions of P-alkyl heterocyclics could be excited by UV light and yields yellow-green emission,whereas this phenomenon was not observed with all the P-aryl derivatives.UV-vis absorption and fluorescence spectra of annelated ?5-phosphanaphthalenes in dichloromethane(10-5M)wereinvestigated.When R = t-Bu,the thermolysis of the annelated ?5-phosphanaphthalenes affords the corresponding trivalent phosphanaphthalene 15.Due to its high reactivity,we trapped it by reaction with 2,3-dimethylbutadiene and sulfur,and the target compound has also been characterized by X-ray crystal structure analysis.