Synthesis of pyrrolobenzothiadiazepines, pyrrolizidines and indoles

In this thesis, novel syntheses of analogues of pyrrolobenzodiazepines (PBDs) are described. These compounds are of great interest as synthetic targets due to their potential medical properties. The first process involved is the intramolecular 1,3‐dipolar cycloaddition between the azide and imine present to form the PBD core, a process that occurs via cycloaddition and extrusion of nitrogen. An azide to nitrile cycloaddition was also explored.
As an extension to azide work, a series of 2‐azidobenzenesulfonamides with homoallylic substituents were investigated as precursors in aza‐Prins reactions. Although this was unsuccessful, it led to the observation of an interesting transamination type process.

The attempted synthesis of the sulfur analogues of Fuligocandins A and B are also discussed. Fuligocandin B is known to sensitise leukaemia cells to apoptosis and thus analogues are worthy targets. Synthetic ease drove us to apply the Eschenmoser episulfide contraction to the synthesis of analogues.
The thesis includes the synthesis of other pyrrolo‐fused systems with a focus on the indolizidines and pyrrolizidines. These were prepared from the reaction of a cyclic imine
with diphenylcyclopropenone (DPP) as illustrated in the Scheme. The imines were reacted with DPP to study the effect of a large substituent at position 3 to investigate its effect on the stereochemical outcome of the reaction.
While accessing these indolizidines we serendipitously synthesised several examples of indoles and quinoline systems.