The versatile chemistry of azidoalkyl enol ethers and their equivalents

This thesis describes the synthesis and intramolecular cycloaddition products of azides tethered to olefins bearing a heteroatom in an attempt to access a proposed triazolium intermediate 77. Chapter 1 covers the synthesis and reactivity of simple di- and trisubstituted azidoalkyl enol ethers. These substrates were found to provide isolable 1,2,3-triazoline products, but displayed a propensity to aromatise to 1,2,3-triazoles upon ionisation. Difficulties in synthesising fully-substituted azidoalkyl enol ethers have precluded a detailed study in this project, though a bias towards α-alkoxy imine formation was suggested. Chapter 2 covers the chemistry of azidoalkyl vinyl bromides. Simple vinyl bromide substrates were found to yield 1-azadienes upon thermolysis, presumably via the dehydrobromination of an α-bromo imine intermediate in situ. In Chapter 3, a brief diversity-oriented synthesis (DOS) campaign was undertaken to demonstrate the potent reactivity of 1-azadiene substrates. 1-Azadienes were found to be versatile intermediates, and a small DOS library was built by exploiting several key reactivity modes. In Chapter 4, two miscellaneous routes towards the desired triazolium intermediate are discussed, and finally an Appendix chapter deals with an attempted total synthesis of salinosporamide C.This thesis is not currently available via ORA