New cyclisations of iminyl radicals generated by flash vacuum pyrolysis
The formation of iminyl radicals from a range of precursors, including hydrazone imines and oxime ethers, under FVP conditions is well documented in the literature.1 Once formed, the iminyl radical can undergo cyclisation onto various aromatic ring systems including phenyl rings, thiophenes and furans to form new fused aromatics.2 The aim of this thesis was to expand the scope of cyclisation of iminyl radical onto pyrrole-type rings and 2-azole rings, generating novel heterocyclic cores via pyrolysis of the corresponding oxime ether precursors. In addition, the cyclisation of iminyl radicals onto C-C double bonds was investigated and afforded isoquinolines shown in Scheme II, providing a new way to synthesise these heterocyclic cores. Mechanistic predictions were supported by DFT calculations in which the thermodynamics and kinetics of the systems were established and the products of iminyl cyclisation reactions were characterised using a range of 2D NMR experiments.
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