This thesis addresses two fundamental areas in contemporary organic chemistry: synthesis of natural products and catalytic asymmetric synthesis. Firstly, a new methodology, developed by our research group, which allows the asymmetric synthesis of lactones, a structural unit ubiquitous in natural products, was utilised in the synthesis of a number of natural product analogues that showed significant biological activity. Secondly, the development of a catalytic asymmetric synthesis of a key structural motif present in a number of natural products and pharmaceuticals was accomplished. During the course of this work we discovered dual stereocontrol, which is significant because it allows the configuration of a new stereocentre to be controlled by a simple change of proton source.