Diasterodivergent synthesis of fused ring systems

Thesis

Introduction

We envisioned using phase transfer catalysis (PTC) to develop asymmetric carba-6π- electrocyclisations. We believed that the configurational lability of 6π systems could be reduced by constraining them within a ring system.

Results and Discussion

En route to the synthesis of a starting material for the transannular electrocyclisation reaction, we noticed that a 5-5-3 fused ring system had formed, in one step, from a linear precursor and as a single diastereomer. We synthesised both geometric isomers of the starting materials, and unexpectedly, the E or Z isomers cyclised to form different products under different reaction conditions. We further investigated the 5-5-3 system, generating substrate scope and computationally and experimentally exploring the mechanism.

Conclusion

In one step we have constructed three carbon-carbon bonds, up to five contiguous stereogenic centres and all as a single diastereomer. We have synthesised 15 examples and have probed the mechanism experimentally and computationally. We have also investigated asymmetric examples of this reaction.

Authors: Kiss, E

• DOI: 10.5287/ora-9omygdk0y
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford