Towards the total synthesis of 1α,25-dihydroxylumisterol

• Main Author: Partridge, Alan
• Other Authors: Craig, Donald
• Published: Imperial College London 2013
• Subjects: 540
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572273

This thesis is divided into three chapters. The first chapter provides a brief review on recent work in the application of cascade cyclisations to the total synthesis of natural products. This is followed by a review of the decarboxylative Claisen rearrangement (dCr), a novel variant of the Ireland-Claisen reaction in which tosylacetic esters of allylic alcohols are transformed into homoallylic sulfones using BSA and potassium acetate, and its applications. The second chapter discusses the results of our studies towards the total synthesis of 1α,25-dihydroxylumisterol via a proposed route containing two key steps; a cascade-inspired, Lewis-acid mediated cyclisation to form the steroid B-ring in I, and the dCr reaction of tosylacetic ester IV to give diene III. Successful syntheses, as well as problems encountered along this route will be discussed, as well as the measures taken to adapt the synthesis to circumvent these problems [Molecular structure diagrams appear here. To view, please open pdf attachment]. The third and final chapter contains experimental procedures and characterisation data for the prepared compounds.