An Asymmetric Total Synthesis of Tupichilignan A using Donor–Acceptor Cyclopropanes: A Structural Revision of Tupichilignan A

An asymmetric total synthesis of tupichilignan A was achieved using enantioenriched donor–acceptor (D–A) cyclopropanes. The key steps include an asymmetric cyclopropanation using the Hayashi–Jørgensen catalyst, an oxy‐homo‐Michael reaction of a bicyclic D–A cyclopropane, an α‐benzylation of a γ‐lactone, a decarboxylation furnishing a trans ‐α,β‐dibenzyl‐γ‐lactone, a configurational inversion of a hydroxy chiral center via oxidation, and a final reduction, all of which occur with high stereoselectivity. The spectral data of the diastereomer previously identified in the literature as tupichilignan A were found to be inconsistent with the reported data for the natural product. On the basis of the spectral data of both of the synthesized diastereomers, the structure of tupichilignan A was revised, and the absolute configuration of the 7 position of tupichilignan A was changed from R to S .