First Enantiocontrolled Formal Synthesis of (+)-Neovibsanin B, A Neurotrophic Diterpenoid

An enantiocontrolled formal synthesis of (+)-neovibsanin B has been achieved by a sequence that applies an asymmetric 1,4-addition of (H2C═CH)2Cu(CN)Li2 to trisubstituted α,β-carboxylic acid derivative 1 to induce the chirality at the C-11 all-carbon quaternary center. Together with a modified Negishi cyclic carbopalladation-carbonylative esterification tandem reaction for constructing the A-ring, the synthesis was completed.