Catalytic Asymmetric Radical–Polar Crossover Hydroalkoxylation

Asymmetric intra­molecular hydrofunctionalization of tertiary allylic alcohols is described. This metal hydride-mediated catalytic radical–polar crossover reaction delivers corresponding epoxides in good to high enantio­selectivity and constitutes the first example of asymmetric hydrogen atom transfer-initiated process. A series of modified cobalt salen complexes has proven optimal for achieving good efficiency and asymmetric induction. Experimental data suggest that cationic cobalt complexes may be involved in the enantio­determining step, where cation−π interactions in the catalyst contribute to the asymmetric induction.