This thesis is divided into two parts. The first part describes the development ofmethodology for the intramolecular Diels-Alder (IMDA) reaction of sulphonyl-substituted trienes. A brief introduction to the area of the IMDA reaction is provided. This provides the basis for the rational development of a new class of IMDA substrate. A series of E- and Z-sulphonyl substituted deca- and undecatrienes was synthesised and their cyclisation behaviour under thermal conditions examined. Cyclisation of (IE, 7E, 9E)-l-phenylsulphonyl-l,7,9-undecatriene gave a 6:1 mixture of cis- and trans-fused bicyclic sulphones. Contrastingly, cyclisation of the corresponding (Z, £ , E)- sulphonyltriene yielded a 3:1 mixture of trans- and cis-fused isomers. These results added weight to the postulate that a suitable dienophile could exert a sereocontrolling influence over the outcome of the IMDA reaction. The lower homologues of these trienes were found to provide similar results. The reaction of a series of a methylated trienes was carried out to examine the degree of stereocontrol exerted by the phenylsulphone group over the [4+2] cycloaddition. Characterisation of the bicyclic sulphones derived from these reactions is supported by X-ray crystallographic evidence and supplemented by chemical correlation.
The second part begins with a review of approaches towards the total synthesis of the CD ring of vitamin D3 and its analogues. This introduces the use of the IMDA reaction as a concise strategy towards the construction of a vitamin D3 CD ring synthon in a stereocontrolled fashion. The synthesis of a suitable model substrate and its cyclisation via a novel IMDA route is described. With the success of this reaction, an
enantiomerically pure triene was synthesised. Cyclisation under thermal conditions led to material suitable for elaboration to the natural product, vitamin D3. The diastereomeric bicyclic tetrahydroindene adducts were epoxidised to allow their separation and characterisation using spectroscopic techniques.