Catalytic Asymmetric Crotylation of Aldehydes: Application in Total Synthesis of (−)‐Elisabethadione

A new, highly efficient Lewis base catalyst for a practical enantio‐ and diastereoselective crotylation of unsaturated aldehydes with E‐ and Z‐crotyltrichlorosilanes has been developed. The method was employed as a key step in a novel asymmetric synthesis of bioactive serrulatane diterpene (?)‐elisabethadione. Other strategic reactions for setting up the stereogenic centers included anionic oxy‐Cope rearrangement and cationic cyclization. The synthetic route relies on simple, high yielding reactions and avoids use of protecting groups or chiral auxiliaries.