First total synthesis of tuberonic acid

A vinyl group as an acetic acid side chain was attached to the optically active monoacetate of 4-cyclopentene-1,3-diol with CH2CHMgBr, LiCl, and a CuCN catalyst to produce the SN2-type product, from which the full carbon skeleton of tuberonic acid was constructed through Mitsunobu inversion, Claisen rearrangement, and Wittig reaction. At the last stage, the THP protective group was removed with MgBr2 in Et2O. The diastereomeric ratio of tuberonic acid and the trans isomer was 92:8 by 1H NMR spectroscopy.