A Highly Efficient Synthesis of the FGH Ring of Micrandilactone A. Application of Thioureas as Ligands in the Co-catalyzed Pauson−Khand Reaction and Pd-Catalyzed Carbonylative Annulation

The functionalized FGH ring system of micrandilactone A was successfully constructed in high selectivity and good yields. The key reactions in our strategy are the Co−thiourea-catalyzed stereoselective, intramolecular Pauson−Khand reaction and Pd−thiourea-catalyzed stereoselective, intramolecular annulation.