This thesis describes work performed towards developing a synthetic approach to the marine alkaloid Batzelladine A and also towards a template system for another marine alkaloid, Ptilomycalin A.
a) A reductive guanidine addition-cyclisation process is employed to prepare a tricyclic model compound for the tricyclic core of Batzelladine A. The bis-a, β-unsaturated precursor, (3E,7E)-2,9-dioxooctadeca-3,7-diene is prepared from succinaldehyde by a Wittig approach. The tricyclic guanidine compound is obtained as a single diastereoisomer and the relative stereochemistry is assigned by nOe experiments and X-ray diffraction analysis of a symmetrical model compound.
b) An ester-substituted precursor to guanidine addition is prepared via a somewhat problematic Knoevenagel condensation. The attempted preparation of a tert-butyl ester derivative of the tricyclic guanidine core of Batzelladine A is also described.
c) This methodology is modified to enable the preparation of the left-hand tricyclic portion of the marine alkaloid Batzelladine F.
d) The guanidine addition-cyclisation process is employed in the diastereospecific synthesis of a hexacyclic guanidine compound to assess the viability of this route for the preparation of an advanced intermediate for a Ptilomycalin A mimic. The compound incorporates two tetrahydropyranyl spiro N,O-acetal units and possesses the same relative
stereochemistry as Ptilomycalin A, determined by X-ray crystallography. Studies towards a pyrrole-fused system are also described.