A series of six 2,5-disubstituted adjacent bis(tetrahydrofuran) stereoisomers with trans/erythro/cis, trans/threo/trans, or cis/threo/cis relative stereochemistry have been synthesized from known dihydroxycyclooctenes via ring opening/cross metathesis and Pd(0)-mediated asymmetric double cycloetherification. The stereochemistry of four of these isomers has been found in the biologically active annonaceous acetogenin natural products. [reaction: see text].
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http://dx.doi.org/10.1021/ol062390l | DOI Listing |
Phytochem Anal
September 2024
Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois Chicago, Chicago, Illinois, USA.
J Nat Prod
February 2024
Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois Chicago, Chicago, Illinois 60612, United States.
Four new adjacent bis-tetrahydrofuran acetogenins, bullacin C (), uvarirufin (), and uvariasolins III () and IV (), along with 11 known acetogenins, were isolated from the stem of . Their structures were elucidated based on spectroscopic data analysis, including 1D and 2D NMR, HRESIMS, and MALDI-MS/MS of the lithium adducts. Absolute configurations were assigned using Mosher ester analysis and ECD measurements.
View Article and Find Full Text PDFRSC Adv
December 2023
College of Pharmacy, Seoul National University Seoul 08826 Korea.
We describe here the highly stereoselective total synthesis of the C acetogenins (3)- and (3)-elatenynes having a 7,12-dibromo-6,9--10,13- adjacent bis-tetrahydrofuran (THF) core. The present synthesis features a highly stereoselective, protecting group-dependent, chelate-controlled intramolecular amide enolate alkylation (IAEA) for the synthesis of key intermediate 7-hydroxy-6,7--6,9--THF intermediate 10, deployment of the sequential ate complex (-BuLi/DIBAL-H) reduction/Keck allylation/cross metathesis (CM) protocol for the stereoselective introduction of the C(10)-C(15) unit, a sequential Sharpless asymmetric dihydroxylation (SAD)/intramolecular Williamson etherification for the construction of the 10,13--THF ring, and a modified Nakata chloromethanesulfonate-mediated S2 displacement for the 7,12-dibromo functionality. Furthermore, our strategy based on chelate-controlled IAEA methodology would provide access to any member of the C adjacent bis-THF acetogenin class.
View Article and Find Full Text PDFOrg Lett
September 2023
College of Pharmacy, Seoul National University, Seoul 08826, Korea.
The total synthesis and structure confirmation of the potent cytotoxic agent (-)-asimitrin (), a C annonaceous acetogenin having a hydroxylated adjacent bis-tetrahydrofuran (THF) core, are described. The present synthesis features a highly stereoselective, chelate-controlled intramolecular amide enolate alkylation (IAEA) for the synthesis of key intermediate 17-hydroxy-16,17--16,19--THF , our direct ketone synthesis/l-Selectride reduction protocol for stereoselective introduction of the C(21)-C(34) unit, Sharpless asymmetric dihydroxylation (SAD), and internal Williamson etherification for construction of the 20,23--THF ring.
View Article and Find Full Text PDFJ Org Chem
August 2021
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, United States.
The chemical examination of two undescribed marine actinobacteria has yielded three rare merosesterterpenoids, marinoterpins A-C (-, respectively). These compounds were isolated from the culture broth extracts of two marine-derived actinomycetes associated with the family Streptomycetaceae, (our strains were CNQ-253 and AJS-327). The structures of the new compounds were determined by extensive interpretation of 1D and 2D NMR, MS, and combined spectroscopic data.
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