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The enantioselective synthesis of the fully functionalized BCDE tetracyclic ring system of propindilactone G (A) is reported. Several synthetic methods were developed and applied to achieve this goal, including: 1) an asymmetric Diels-Alder reaction in the presence of Hayashi's catalyst for the synthesis of optically pure key intermediate 3; 2) an intramolecular Pauson-Khand reaction (PKR) for the stereoselective synthesis of the BCDE ring with an all-carbon chiral quaternary center at the C13 position by using the TMS-substituted acetylene as the substrate; and 3) Pd-catalyzed reductive hydrogenolysis for the stereoselective synthesis of the fully functionalized BCDE tetracyclic ring system. The chemistry developed herein provided a greater understanding of the total synthesis propindilactone G (A) and its analogues.

Thioureas are air and moisture stable, and they can coordinate to various metal centers, making their derivatives versatile ligands for transition-metal-catalyzed reactions. This account provides an overview of recent developments in the use of thioureas as ligands in organometallic-catalyzed reactions, with particular emphasis on their application to the total synthesis of natural products. 1 Introduction 2 Development of Thioureas as Ligands in Transition-Metal-Catalyzed Reactions 2.1 Carbonylative Annulation 2.2 Pauson–Khand Reaction (Intramolecular and Intermolecular) 2.3 Thiourea–Palladium-Catalyzed Carbonylation of Terminal Olefins 2.4 Thiourea–Palladium-Catalyzed Heck Coupling Reaction 2.5 Suzuki Coupling and Suzuki Carbonylative Reaction 2.6 Negishi Coupling 2.7 Other Reactions 3 Applications in Total Synthesis of Natural Products 3.1 (±)-Schindilactone A 3.2 Crisamicin A 4 Conclusion and Outlook

Herein, we report the development of a new method for the syntheses of substituted triphenylenes from the corresponding 1,2,4-trisubstituted arenes, which were themselves generated in a highly regioselective manner according to an intermolecular alkyne cyclotrimerization reaction that was catalyzed by a novel Co-TMTU complex. This highly regioselective reaction for the formation of 1,2,4-trisubstituted arenes will be a valuable addition to the plethora of tools already available to synthetic chemists and encourage further mechanistic studies of this important alkyne trimerization process.

Th complex is generated generated in situ by reduction of CoBr2 with Zn and efficiently promotes the Pauson—Khand reaction affording structurally diverse cyclopentenones (20 examples).

A diversity-oriented approach for the synthesis of structurally diverse catechins was achieved in good yields via thiourea/AuCl(3)/AgOTf-catalyzed annulations of aryl epoxides under mild conditions. This new protocol provides a highly efficient entry to a library of catechins-derived natural products, notably anti-HIV agent 8-C-ascorbyl-(-)-epigallocatechin.

A general and robust transition-metal-catalyzed Pauson-Khand reaction is still difficult to achieve. In this contribution, we describe our recent observations on the effect of lithium chloride on Pauson-Khand reactions catalyzed by palladium(II) chloride-tetra-methylthiourea; this allows structurally diverse cyclopentenones to be prepared effectively.

Two types of quinoline scaffolds were constructed in a combinatorial format via the Ugi four-component reaction (U-4CR) and Pd-catalyzed intramolecular arylation reaction. The scope of this two-step synthetic sequence was examined from commercially available and synthetically accessible starting materials.

A convenient and effective synthesis of enantiomerically pure macrocyclic dioxopolyamine 3 and its derivatives 4–9 is presented. Macrocyle 3, derived from l-proline, was prepared in high overall yield and easily modified. 8 and 9 were prepared by modified Mannich reaction in good yields.