C-O Ring Construction: Petromyroxol (Fernandes), Hedyosumin A (Chen/Yang), Cephalosporolide J (Ota/Miyaoka), Malettenin C (Yokoshima), xyloketal B (Narayan), Lucidumone (Kawamoto/Ito)

Petromyroxol (3) was isolated from > 106 liters of sea water conditioned with larval sea lamprey, Petromyzon marinus. Rodney A. Fernandes of the Indian Institute of Technology Bombay assembled the core of 3 by selectively cyclizing the diol 1 to the tetrahydrofuran 2 (Chem. Commun. 2023, 59, 2007, DOI: 10.1039/D2CC04579F; Chem. Commun. 2022, 58, 11921, DOI: 10.1039/D2CC04574E).

Hedyosumin A (7) was isolated from the aerial parts of the Chinese flowering plant Hedyosmum orientale. Jia-Hua Chen and Zhen Yang of Peking University constructed the tricyclic core 6 of 7 by the Pt-catalyzed coupling of the keto alkyne 4 with acetaldehyde silyl enol ether 5 (Tetrahedron Lett. 2022, 102, 153946. DOI: 10.1016/j.tetlet.2022.153946).

Cephalosporolide J (10) was isolated during a bioassay-guided investigation of the deep-sea derived fungus Penicillium commune. Koichiro Ota and Hiroaki Miyaoka of the Tokyo University of Pharmacy and Life Sciences initiated their synthesis of 10 with the Sharpless asymmetric dihydroxylation of the unsaturated ester 8, leading to the lactone 9 (Synlett 2022, 34, 271). Fernando Sartillo-Piscil reported a parallel investigation (J. Org. Chem. 2023, 88, 4880. DOI: 10.1021/acs.joc.3c00251).

Malettenin C (13) was isolated from the stromata of Hypoxylon sp. growing on dead aspen logs. Following the lead of Kende and Koch, Satoshi Yokoshima of Nagoya University assembled the tropolone 12 by the oxidative cyclization of the phenol 11, followed by treatment with base (Org. Lett. 2023, 25, 4530. DOI: 10.1021/acs.orglett.3c01565).

Originally isolated from the marine fungus Xylaria sp. of the South China Sea, xyloketal B (17) protects endothelial cells from oxidized LDL-induced injury at 0.3 µM. Alison R. H. Narayan of the University of Michigan assembled the precursor iodide 16 by the diastereoselective combination of the triol 14 with the dihydrofuran 15 (Org. Lett. 2023, 25, 1547. DOI: 10.1021/acs.orglett.3c00334).

Lucidumone (20), isolated from the mushroom Ganoderma lucidum, selectively inhibits COX-2. En route to 20, Yuichiro Kawamoto and Hisanaka Ito, also of the Tokyo University of Pharmacy and Life Sciences, selectively cyclized the triol 18 to the pentacyclic ether 19 (Angew. Chem. Int. Ed. 2023, 62, e202304132. DOI: 10.1002/anie.202304132).