Asymmetric synthesis of the fully functionalized six-membered ring of trigoxyphin A.

An asymmetric synthesis strategy of the fully functionalized six-membered ring of trigoxyphin A, a daphnane-type diterpenoid, has been accomplished concisely from a d-tartrate derivative. Key elements of this synthesis involve the tandem ozonization/intramolecular HWE reaction to construct the α,β-unsaturated cyclohexenone skeleton, the radical cyclization to introduce the C8 chirality and sequential Kumada cross-coupling/hydroboration-oxidation to introduce the C11 chirality. The target substructure could be synthetically achieved on a multi-gram scale.