Silacycles: novel reagents in asymmetric synthesis

Abstract

Silicon based organic reagents have enjoyed a wealth of applications in the last thirty year. However, the development of organosilanes for asymmetric synthesis has been less prolific. The drawbacks of using 'Si-centred' chiral organosilanes has led to 'C- centred' organosilicon compounds being the substrate of choice. This research has been directed at the synthesis and application of C(_2) symmetric 'C-centred' cyclic organosilicon species and their potential applications in asymmetric synthesis. A variety of synthetic methods have been considered, the most successful of which has been the double asymmetric hydroboration of substituted divinylsilanes. This has allowed the use of unusual boron redistribution chemistry to give access to both acyclic and cyclic rmw-substituted organosilicon compounds with high stereoselectivity. A new method for the synthesis of dichlorosilanes from their diphenyl analogue has been developed and has been shown to occur almost instantaneously and in good yield. Finally, the application of dichlorosilacycles in tethered Diels-Alder reactions has been investigated and has been shown to give enhanced rates of reaction when compared to acyclic silicon tethers.