Co-Catalyzed Direct Addition of Allylic C(sp3)-H Bonds to Ketones.

By using Co(acac)2/Xantphos with AlMe3, the C(sp3)-H bonds of allylarene derivatives were cleaved for reaction with various ketones, affording the homoallylic alcohols in moderate to good yields. The branch/linear selectivity depended on the steric and electronic factors of the ketone electrophiles. The intermediate in this reaction is thought to be a low-valent allylcobalt(I) species, which exhibits high nucleophilicity toward ketones.