Other Methods for Carbocyclic Construction: Dipiperamide A (Yoon), Acanthodoral (Kalesse), Dysidavarone A (Chong/Lu), Providencin (Roche/West), Vinigrol(Luo), Cochlearol B (Zhao)

The truxilic acids, represented by dipiperamide A (3), are head-to-tail dimers. Tehshik P. Yoon of the University of Wisconsin showed that the head-to-tail product 2 was formed when the hydrochloride of the acyl imidazole 1 was irradiated in the solid state (J. Am. Chem. Soc. 2024, 146, 14948. DOI: 10.1021/jacs.4c04706).

Acanthodoral (6), isolated from the dorid nudibranch Acanthodoris nanaimoensis, showed antibiotic and antifungal activity. Markus Kalesse of Leibniz University constructed 6 by way of the reductive rearrangement of the allene photoadduct 4 to 5 (Org. Lett. 2024, 26, 2893. DOI: 10.1021/acs.orglett.3c03717).

Dysidavarone A (10) was isolated from the South China Sea sponge Dysidea avara. Chuanke Chong and Zhaoyong Lu of Nankai University assembled 10 by the alkylation/arylation of the Wieland-Miescher ketone 7 with the dibromide 8, leading to 9 (Synlett 2024, 35, 582. DOI: 10.1055/a-2066-0860).

Providencin (12), which showed in vitro cytotoxic activity, was isolated along with bippinatin E (11) from the Caribbean gorgonian octocoral Antillogorgia kallos. The co-occurrence of these two natural products raised the possibility that one was derived from the other via photochemical cyclization. In the event, Stéphane P. Roche and Lyndon West of Florida Atlantic University observed that irradiation of 11 led to 12 and its regioisomer from C-14 insertion in a ratio of 1:3.7. It would be interesting to know if that ratio were to change on irradiation in the solid state (Org. Lett. 2024, 26, 1123. DOI: 10.1021/acs.orglett.3c03604).

A challenge in the total synthesis of vinigrol (15) has been the closing of the medium ring. Tuoping Luo of Peking University approached this problem directly, first optimizing the preparation of the cyclodecenone 14 from the limonene-derived alcohol 13, then carrying it on to 15 (J. Org. Chem. 2024, 89, 1709. DOI: 10.1021/acs.joc.3c02407).

Cochlearol B (18) was isolated from the fungal strain Virgaria nigra F-5408. Yu-Ming Zhao of Shanxi Normal University developed a route to 18 based on the photochemical cyclization of 16 to 17 (Chem. Eur. J. 2024, 30, e202400084. DOI: 10.1002/chem.202400084).

We all admire the "Eureka!" moments of others, and hope for those moments for ourselves. Jeffrey I. Seeman of the University of Richmond and Judy I. Wu of the University of Houston, continuing their documentation of the history of chemistry, asked 18 chemists across a wide range of disciplines about their thought processes (ACS Central Sci. 2024, 10, 1980. DOI: 10.1021/acscentsci.4c00802).