Biomimetic Total Synthesis of (±)-Carbocyclinone-534 Reveals Its Biosynthetic Pathway

Radical Fluorosulfonylation/Double Diels-Alder Sequence to Access Tricyclo[3.2.1.02,7]octanes

A cascade strategy for the rapid construction of tricyclo[3.2.1.02,7]octanes is reported. This one-pot, two-step sequence can be efficiently accomplished by utilizing readily available propargylic alcohols as the starting materials and FSO2Cl as the fluorosulfonyl radical precursor. The FSO2-functionalized tricyclooctane products, bearing multiple reactive sites, are poised for postderivatizations. Based on mechanism studies, a cascade sequence involving radical hydro-fluorosulfonylation, dehydration, and a double Diels-Alder reaction has been proposed.

Design, Synthesis, and Antibacterial Activity of Stilbene Derivatives against Phytopathogenic Bacteria

The increasing resistance of phytopathogenic bacteria to chemical pesticides has underscored the urgent need for novel bactericidal agents. In this study, we designed, synthesized, and evaluated a series of stilbene derivatives for their antibacterial activity against six strains of plant-pathogenic bacteria. Among them, compound ST-A-8 showed the optimal activity against Xanthomonas oryzae pv oryzae (Xoo) and Erwinia aroideae, with both MIC values of 1.56 μg/mL, which was more potent than the commercialized antibacterial agent thiodiazole copper. Furthermore, the mechanism of ST-A-8 on Xoo was preliminarily investigated, and the results showed that ST-A-8 inhibited the biofilm formation as well as the production of extracellular polysaccharides in Xoo. Additionally, it disrupted the integrity of the cell membrane and increased the production of ROS, leading to lipid peroxidation of the cell membrane. Therefore, compound ST-A-8 may serve as a potential novel bactericide for the control of plant bacterial diseases.

Bioinspired Synthesis of Microstegiol and Biosynthetically Related Skeleton-Rearranged Abietanes

We report a bioinspired synthesis of microstegiol and biosynthetically related skeleton-rearranged abietane diterpenoids from commercially available carnosic acid. The strategy features a Wagner-Meerwein type methyl migration followed by several cascade transformations, enabling the divergent synthesis of five abietane diterpenoids, including viridoquinone, prattinin A, saprorthoquinone, microstegiol, and 1-deoxyviroxocin.

Asymmetric Synthesis and Biological Evaluation of Platensilin, Platensimycin, Platencin, and Their Analogs via a Bioinspired Skeletal Reconstruction Approach

Platensilin, platensimycin, and platencin are potent inhibitors of β-ketoacyl-acyl carrier protein synthase (FabF) in the bacterial and mammalian fatty acid synthesis system, presenting promising drug leads for both antibacterial and antidiabetic therapies. Herein, a bioinspired skeleton reconstruction approach is reported, which enables the unified synthesis of these three natural FabF inhibitors and their skeletally diverse analogs, all stemming from a common ent-pimarane core. The synthesis features a diastereoselective biocatalytic reduction and an intermolecular Diels-Alder reaction to prepare the common ent-pimarane core. From this intermediate, stereoselective Mn-catalyzed hydrogen atom-transfer hydrogenation and subsequent Cu-catalyzed carbenoid C-H insertion afford platensilin. Furthermore, the intramolecular Diels-Alder reaction succeeded by regioselective ring opening of the newly formed cyclopropane enables the construction of the bicyclo[3.2.1]-octane and bicyclo[2.2.2]-octane ring systems of platensimycin and platencin, respectively. This skeletal reconstruction approach of the ent-pimarane core facilitates the preparation of analogs bearing different polycyclic scaffolds. Among these analogs, the previously unexplored cyclopropyl analog 47 exhibits improved antibacterial activity (MIC80 = 0.0625 μg/mL) against S. aureus compared to platensimycin.

Strategies for the Construction of Benzobicyclo[3.2.1]octane in Natural Product Synthesis

Benzobicyclo[3.2.1]octane is a cage-like unique motif containing a bicyclo[3.2.1]octane structure fused with at least one benzene ring. It is found in various natural products that exhibit structural complexities and important biological activities. The total synthesis of natural products possessing this challenging structure has received considerable attention, and great advances have been made in this field during the past 15 years. This review summarizes thus far achieved chemical syntheses and synthetic studies of natural compounds featuring the benzobicyclo[3.2.1]octane core. It focuses on strategic approaches constructing the bridged structure, aiming to provide a useful reference for inspiring further advancements in strategies and total syntheses of natural products with such a framework.

Synthetic Approaches to the New Drugs Approved During 2022

In 2022, 23 new small molecule chemical entities were approved as drugs by the United States FDA, European Union EMA, Japan PMDA, and China NMPA. This review describes the synthetic approach demonstrated on largest scale for each new drug based on patent or primary literature. The synthetic routes highlight practical methods to construct molecules, sometimes on the manufacturing scale, to access the new drugs. Ten additional drugs approved in 2021 and one approved in 2020 are included that were not covered in the previous year's review.

Total Synthesis of (±)-Spiroaxillarone A via a Reversible Sulfa-Michael Addition

A bioinspired strategy is described for the total synthesis of spiroaxillarone A, which exhibited significant antimalarial activity against resistant Plasmodium falciparum (IC₅₀ = 2.32 μM). The key steps include an intermolecular ethanethiol Michael addition, o-quinone Michael addition, and subsequent β-ethanethiol elimination. This synthetic sequence provides a potential biosynthetic pathway of spiroaxillarone A.

Bioinspired Network Analysis Enabled Divergent Syntheses and Structure Revision of Pentacyclic Cytochalasans

We accomplished the divergent total syntheses of ten pentacyclic cytochalasans (aspergillin PZ, trichodermone, trichoderones, flavipesines, and flavichalasines) from a common precursor aspochalasin D and revised the structures of trichoderone B, spicochalasin A, flavichalasine C, aspergilluchalasin based on structure network analysis of the cytochalasans biosynthetic pathways and DFT calculations. The key steps of the syntheses include transannular alkene/epoxyalkene and carbonyl-ene cyclizations to establish the C/D ring of pentacyclic aspochalasans. Our bioinspired approach to these pentacyclic cytochalasans validate the proposed biosynthetic speculation from a chemical view and provide a platform for the synthesis of more than 400 valuable cytochalasans bearing different macrocycles and amino-acid residues.