Reagent Directing Group Controlled Organic Synthesis: Total Synthesis of (R,R,R)‐α‐Tocopherol

The direct approach: The efficient use of substrate control has served as the basis for the enantioselective total synthesis of (R,R,R)-α-tocopherol. A single reagent directing group (ortho-diphenylphosphanyl benzoate, o-DPPB) served to control the stereoselectivity of a rhodium-catalyzed hydroformylation reaction and the directed allylic substitution as the fragment-coupling step (see picture).