Total Synthesis of (-)-3-Oxoisotaxodione.

The first total synthesis of the abietaquinone methide diterpenoid (-)-3-oxoisotaxodione is reported. The key enabling step is the use of a chiral bicyclic hydrazide as an organocatalyst for the enantioselective polyene cyclization of a ()-polyene substrate to form the -decalin core of the natural product. The α-oxo--quinone methide unit is formed by a two-step oxidation from a phenol, enabling an efficient synthesis of the natural product.