Asymmetric Total Synthesis of Lancifodilactone G Acetate. 1. Diastereoselective Synthesis of CDEFGH Ring System

Evolution of Pauson-Khand Reaction: Strategic Applications in Total Syntheses of Architecturally Complex Natural Products (2016–2020)

Metal-mediated cyclizations are important transformations in a natural product total synthesis. The Pauson-Khand reaction, particularly powerful for establishing cyclopentenone-containing structures, is distinguished as one of the most attractive annulation processes routinely employed in synthesis campaigns. This review covers Co, Rh, and Pd catalyzed Pauson-Khand reaction and summarizes its strategic applications in total syntheses of structurally complex natural products in the last five years. Additionally, the hetero-Pauson-Khand reaction in the synthesis of heterocycles will also be discussed. Focusing on the panorama of organic synthesis, this review highlights the strategically developed Pauson-Khand reaction in fulfilling total synthetic tasks and its synthetic attractiveness is aimed to be illustrated.

Recent Advances in the Total Synthesis of Natural Products Containing Eight-Membered Carbocycles (2009-2019)

Natural products containing eight-membered carbocycles constitute a class of structurally intriguing and biologically important molecules such as the famous diterpenes taxol and vinigrol. Such natural products are being increasingly investigated because of their fascinating architectural features and potent medicinal properties. However, synthesis of natural products with cyclooctane moieties has proved to be highly challenging. This review highlights the recently completed total syntheses of natural products with eight-membered carbocycles with a focus on strategic considerations. A collection of 27 representative studies from the literature covering the decade from 2009 to 2019 is described in chronological order with relevant studies grouped together, including syntheses of the same natural product by different research groups using different strategies. Finally, a summary and outlook including a discussion of the major features of each strategy used in the syntheses are presented. This review illustrates the diversity and creativity in the elegant synthetic designs of eight-membered carbocycles. We hope this review will provide timely illumination and beneficial guidance for future synthetic efforts for organic chemists who are interested in this area.

Recent progress in the synthesis of limonoids and limonoid-like natural products

Recent progress in syntheses of limonoids and limonoid-like natural products is reviewed. The current “state-of-art” advance on novel synthetic strategy are summarized and future outlook will be presented.

Synthesis of Oxa-Bridged Medium-Sized Carbocyclic Rings via Prins Cyclization

Herein, we report a new method for the synthesis of oxa-bridged carbocyclic units based on intramolecular Prins reaction of dioxinones. Our new synthetic approach is flexible and practical and has been successfully applied to the preparation of highly functionalized seven-, eight-, and nine-membered carbocycles. The potential utility of this approach has also been demonstrated in a model study toward construction of the 7,8-fused ring system presented in neoabyssomicin D.

Total synthesis of sesterterpenoids

Total syntheses of biologically and structurally fascinating sesterterpenoids published between Jan. 2012 and Jan. 2018 are summarized and discussed here.

Asymmetric total synthesis of (+)-astellatol and (−)-astellatene

Here we describe the full account of the total synthesis of (+)-astellatol, as well as the first total synthesis of (−)-astellatene.

Asymmetric Total Synthesis of Lancifodilactone G Acetate. 2. Final Phase and Completion of the Total Synthesis

The asymmetric total synthesis of lancifodilactone G acetate was accomplished in 28 steps. The key steps in this synthesis include (i) an asymmetric Diels-Alder reaction for formation of the scaffold of the BC ring; (ii) an intramolecular ring-closing metathesis reaction for the formation of the trisubstituted cyclooctene using a Hoveyda-Grubbs II catalyst; (iii) an intramolecular Pauson-Khand reaction for construction of the sterically congested F ring; (iv) sequential cross-metathesis, hydrogenation, and lactonization reactions for installation of the anomerically stabilized bis-spiro ketal fragment of lancifodilactone G; and (v) a Dieckmann-type condensation reaction for installation of the A ring. The strategy and chemistry developed for the total synthesis will be useful in the synthesis of other natural products and complex molecules.