Anti-Diastereoselective Synthesisof CF3-Containing Spirooxazolines and Spirooxazinesvia Regiospecific Trifluoromethylative Spirocyclization by PhotoredoxCatalysis.

A novel synthesisof CF3-containing spirooxazolinesand spirooxazines has been developed. Regiospecific trifluoromethylativespirocyclization (CF3-spirocyclization) of cyclic alkenesbearing an amide pendant mediated by photoredox catalysis is a usefulstrategy for construction of a C(sp3)–CF3bond and an spirooxazoline or spirooxazine ring onto CCbonds 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-containingspirooxazolines and spirooxazines in anti-fashionwith respect to the CF3group and the oxygen atom of thespirocycles. [ABSTRACT FROM AUTHOR]