Asymmetric Total Synthesis of Propindilactone G, Part 1: Initial Attempts towards the Synthesis of Schiartanes

Our first-generation synthetic study towards the total synthesis of propindilactone G (1) and its analogues is reported. The key synthetic steps were an intramolecular Pauson-Khand reaction (PKR) and a vinylogous Mukaiyama reaction (VMAR). The stereoselective synthesis of the CDE ring moiety with an all-carbon quaternary center through a PKR was difficult, whilst a VMAR afforded a product with the opposite stereochemistry at the C20 position on the side chain. These results led us to redesign our synthetic strategy for the total synthesis of compound 1.