The thesis introduces the azepinoindole as a subunit of the Stemona alkaloid family of
natural products, and outlines a cycloaddition strategy towards this heterocycle. The
strategy is based on azomethine imine cycloaddition, and the generation and reactivity of
azomethine imines are introduced.
Previous work on 1 ,3-dipolar cycloaddition in one-pot, on l-benzyl-4,5-dihydroimidazole
(113a) and l-benzyl-4-phenyl-4,5-dihydroimidazole (113b) as starting materials with
ester-activating dipolarophile and giving achiral and chiral pyrrolidines, respectively is
The work carried out during the course of this PhD. has been on the 1,3-dipolar
cycloadditions of new dihydroimidazolium ylides prepared by N-alkylation of different Nsubstituted
dihydroimidazoles. Several new N-substituted dihydroimidazoles have been
prepared both achiral and chiral. New routes to the chiral dihydroimidazoles have been
This thesis shows the various cycloaddition reactions that have been performed using esteractivated
and sui fur-activated dipolarophiles with different N-substituted achiral
dihydroimidazoles giving achiral cycloadducts. The ester-activated dipolarophiles gave
endo-cycloadducts whereas the sui fur-activated dipolarophiles have shown exocycloadducts.
When the cycloaddition was repeated using sui fur-activated dipolarophiles but this time
with different chiral N-substituted dihydroimidazoles, an unexpected enda stereochemistry
was observed with all except one adduct. Structural studies on the chiral cycloadducts
indicated that racemisation had occurred at an early stage in the precursor
Work has been carried out for the extension of the side chain of the pyrrolidine allowing
for the formation of six and seven-membered rings required in the synthesis of Stemana
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.