ChemChat

Leading Question: What is TFDO?

Trifluoromethyl dioxirane (TFDO) is a stereoselective oxidizing reagent typically used to insert an oxygen atom to an unactivated C-H bond.

Oxidation usually happens at the tertiary C-H bond to afford a regioselective and stereoselective oxygenated product. However, it has been found that stereoselectivity can be rendered when distant substituents on the molecule induces electron-withdrawing effect on the reactive C-H site. Accordingly, epoxidation of molecule 48 afforded a diastereomeric mixture of epoxide 49 and 50 rather than just one stereisomer.

The synthesis of TFDO can be integrated into the epoxidation protocol (in situ) using trifluoroacetone, oxone and sodium bicarbonate under neutral pH condition.

Reference: Yang, D.; Wong, M.; Yip, Y. J. Org. Chem. 1995, 60, 3887-3889.