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Monday, May 15, 2023
Douglass F. Taber
University of Delaware

C-O Ring Construction: Spiroapplanatumine O (Jahn), Alcyonolide (Hosokawa), Wentilactone A (Xu/Yu), Aquilanol A (Stathakis), Thallusin (Arndt), Neobraclactone C (Cheng/Liu)

Spiroapplanatumine O (3) was isolated from Ganoderma applantum, a wood-decaying fungus that is widely used in traditional medicinal chemistry. Ullrich Jahn of the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences assembled the ketone 2 via the cyclization of the aryl triflate 1 (Org. Lett. 2022, 24, 4552. ).

Alcyonolide (7), isolated from a broth of an Okinawan soft coral of the genus Alcyonium, showed activity against HCT116 and NBT-T2 cells. Seijiro Hosokawa of Waseda University prepared the bicyclic core 6 of 7 by the hetero Diels-Alder addition of the alkoxy enone 5 to the unsaturated aldehyde 4 (J. Org. Chem. 2022, 87, 15492. ).

Wentilactone A (10), isolated from the mold Aspergillus wentii EN-48, induced G2/M phase arrest and the mitochondrial-related apoptosis of lung cancer cells. En route to 10, Peng Xu and Biao Yu of SIOC cyclized the acid 8 to the lactone 9 (Chem. Commun. 2022, 58, 12487. ).

Aquilanol A (13) was isolated from the agarwood of Aquilaria malaccensis, produced in the heartwood of the tree on infection by the fungus Phialophora parasitica. Christos I. Stathakis of the Aristotle University of Thessaloniki effected bromination and elimination of caryophyllene oxide (11) to give the allylic alcohol 12, then cyclized that to 13 (Org. Lett. 2022, 24, 6242. ).

Thallusin (16), isolated from the bacterium Cytophaga sp. strain YM2-23, induces stable thalus formation in the chlorophyte Gayralia oxyspermum. Hans-Dieter Arndt of the Friedrich-Schiller-Universitšt Jena established the dihydropyran ring of 16 by the Au/Ag-promoted iodocyclization of the allene 14 to 15 (Angew. Chem. Int. Ed. 2022, 61, e202206746. ).

Neobraclactone C (17) was isolated from the leaves of the Chinese tropical tree Garcinia anomala along with neobraclactones A and B. The latter showed pronounced growth inhibitory activity against the human leukemia cell line K562 and HL-60. Maosheng Cheng and Yongxiang Liu of Shenyang Pharmaceutical University assembled the lactone 18 by the cyclization of the carvone-derived alcohol 17 (Org. Lett. 2022, 24, 9485. ).

D. F. Taber, Org. Chem. Highlights 2023, May 15.