We are interested in the little known Wadsworth-Emmons cyclopropanation which involves the reaction between a stabilised phosphonate anion e.g triethylphosphonoacetate and an epoxide. We have recently discovered that substituted phosphonate esters can be used to synthesise quaternary cyclopropyl esters in a highly diastereocontrolled manner. Overall, this process converts a cheap and easy to establish C-O chiral centre (i.e. that of the epoxide) into one tertiary and one all carbon, quaternary stereocentre of much higher value in a single operation.
We have also recently shown that this somewhat forgotten and little used reaction is not limited to the synthesis of cyclopropyl esters and have extended this process to groups with a similar anion stabilising ability such as sulfones. Epoxides can therefore be directly converted to trans-cyclopropyl sulfones.