New aspects of phosphirane chemistry

Abstract

This thesis provides a detailed account of author's exploration on new aspects of phosphirane chemistry. Chapter one briefly reviews the theoretical and experimental works on phosphiranes that have been published until the middle of 2014. Chapter two describes the investigation on the influence of additional strain on phosphiranes. The subjects of the investigation are norbornane-annulated 1-methylphosphirane complexes. The stereochemistry of these complexes has further strained the annulated phosphiranes, leading to a number of structural distortions and selective decomplexation by CO under pressure. Chapter two also recounts the serendipitous discovery of phosphorus dimers from the thermolysis of 7-allyl-7phosphanorbornadiene complex. Chapter three illustrates the study on the activation of 1chlorophosphirane by aluminium trichloride. The subject of the study is cyclohexane-annulated 1-chlorophosphirane complex. It undergoes AlCl 3-catalysed electrophilic aromatic substitution with thiophene and ferrocene to produce 1-(2-thienyl)-and 1-ferrocenylphosphirane complexes respectively. In the absence of electron-rich arenes, a P-C bond cleavage catalysed by AlCl 3 takes place yielding dichloro(cyclohexyl)phosphine complex. The transient ferrocenylphosphinidene complex can be generated from 1-ferrocenylphosphirane complex and trapped with diphenylacetylene, trans-stilbene and water. 1.4.4 Formation of Two P-C Bonds 1.5 Conclusion References Chapter 2. Highly Strained Annulated Phosphiranes 2.1 Introduction 2.2 Results and Discussion 2.3 Conclusion 2.4 Experimental References Chapter 3. Activation of 1-Chlorophosphirane Complex by Aluminium Trichloride 3.1 Introduction 3.2 Results and Discussion 3.3 Conclusion 3.4 Experimental References Appendix vi LIST OF SCHEMES Scheme 1.1 Ring opening of aziridine-2-t-butyl carboxylate by primary amine Scheme 1.2 Copper-catalyzed ring expansion of vinyl oxirane Scheme 1.3 Ring cleavage by HCl or MeOH at room temperature Scheme 1.4 Hydrolysis of phosphirane with lone-pair-bearing substituent on ring carbon Scheme 1.5 Reaction of phospha[3]radialenes with dichlorophosphines Scheme 1.6 Ring-opening of phosphirane oxide by lithium amide Scheme 1.7 Ring opening of phosphirane tungsten complex by lithium amide Scheme 1.8 Synthesis of 1-phosphapentadienyl complex from 2-vinylphosphirane complex Scheme 1.9 Ring-opening of phosphirane complex via nucleophilic attack at phosphorus Scheme 1.10 Mechanism of ring opening of phosphiranes Scheme 1.11 Reaction of vinylphosphirane with methylenetrimethylphosphorane Scheme 1.12 Phosphirane-vinylphosphine rearrangement Scheme 1.13 Rearrangement of 2-chlorophosphirane into vinylchlorophosphine Scheme 1.14 Synthesis of triafulvene with phosphaspiropentene as intermediate Scheme 1.15 Ring opening of phosphiranium salt Scheme 1.16 Cationic ring-opening polymerisation of phosphirane vii Scheme 1.17 Thermal cleavage of phosphirane oxide Scheme 1.18 Thermal splitting of phosphirane yielding chloro(methylene)phosphine Scheme 1.19 Photolysis of 1-mesitylphos...