Anti-Diastereoselective Synthesis of CF3-Containing Spirooxazolines and Spirooxazines via Regiospecific Trifluoromethylative Spirocyclization by Photoredox Catalysis.

A novel synthesis of CF3-containing spirooxazolines and spirooxazines has been developed. Regiospecific trifluoromethylative spirocyclization (CF3-spirocyclization) of cyclic alkenes bearing an amide pendant mediated by photoredox catalysis is a useful strategy for construction of a C(sp(3))-CF3 bond and an spirooxazoline or spirooxazine ring onto C═C bonds via a single step. The key intermediate is α-CF3-substituted carbocationic species smoothly generated from single-electron-transfer (SET) photoredox processes, which results in diastereoselective spirocyclization. This is the first example of synthesis of CF3-containing spirooxazolines and spirooxazines in anti-fashion with respect to the CF3 group and the oxygen atom of the spirocycles.