Other Methods for Carbocyclic Construction: Cep-212 (Adachi/Nishikawa), Vibralactone (Nelson), Viridianol (Banwell), Flavisiamine F (Xia), Fasicularin (Sato/Chida), Cyclocitrinol (Gui)

Cep-212 (3) is thought to be an intermediate in the biosynthesis of tetrodotoxin. En route to 3, Masaatsu Adachi and Toshio Nishikawa of Nagoya University observed remarkable diastereocontrol in the hetero-Diels-Alder cyclization of 1 to 2 (Org. Lett. 2019, 21, 780. DOI: 10.1021/acs.orglett.8b04043).

Vibralactone (6) is a promising lead compound as an inhibitor of pancreatic lipase. Hosea M. Nelson of UCLA prepared 6 by way of the photochemical transformation of 4 to 5 (Angew. Chem. Int. Ed. 2019, 58, 1724. DOI: 10.1002/anie.201812711).

Viridianol (9) was isolated from the red seaweed Laurencia viridis. En route to 9, Martin G. Banwell of the Australian National University devised the photochemical 1,3 acyl migration of 7 to 8 (J. Org. Chem. 2018, 83, 14049. DOI: 10.1021/acs.joc.8b02626).

Flavisiamine F (12) was isolated from the leaves of the southeast Asia tree Kopsia flavida. In the course of a synthesis of 12, Chengfeng Xia of Yunnan University used a photochemically-activated Ir catalyst to cyclize 10 to 11 (Angew. Chem. Int. Ed. 2019, 58, 5443. DOI: 10.1002/anie.201901241).

Fasicularin (15), isolated from the marine invertebrate Nephteis fasicularis, causes strand cleavage of DNA selectively at guanine residues. Takaaki Sato and Noritaka Chida of Keio University devised a synthesis of 15 based on the cyclization of 13 to 14 (Org. Lett. 2019, 21, 1868. DOI: 10.1021/acs.orglett.9b00478).

Cyclocitrinol (18), isolated from a terrestrial Penicillium citrinum, shows potential for the treatment of spinal cord injuries and stroke. On the way to 18, Jinghan Gui of the Shanghai Institute of Organic Chemistry designed the stereoretentive conversion of 16 to 17 (J. Am. Chem. Soc. 2019, 141, 5021. DOI: 10.1021/jacs.9b00925).