Macrocyclic hosts, such as cucurbit[8]uril (CB8), can significantly influence the outcomes of chemical reactions involving encapsulated reactive guests. In this study, we demonstrate that CB8 completely reverses the stereoselectivity of intramolecular [2+2] photo-cycloaddition reactions. Notably, it was also found that CB8 can trigger the unreactive diene to be reactive.
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http://dx.doi.org/10.1039/d3cc05783f | DOI Listing |
Molecules
December 2024
Department of Chemistry and Biochemistry, Augustana University, Sioux Falls, SD 57197, USA.
This study examined the chemoselectivity and diastereoselectivity of silyl nitronate alkenyn-nitroethers in Intramolecular Silyl Nitronate Cycloadditions (ISNCs) to produce isoxazole derivatives with interesting medicinal properties. These reactions resulted in the formation of either dihydrofuro[3,4-c]isoxazolines/isoxazolidines and/or alkynyl moieties attached to 2,5-dihydrofuryl carbonyls. This study also discerned the diastereoselectivities of the resulting cyclic adducts and compared them to previous findings.
View Article and Find Full Text PDFTransition metal-catalyzed carbocyclization reactions provide a powerful method for the stereoselective assembly of complex, highly substituted (poly)cyclic scaffolds. Although 1,6-enynes are common substrates for these transformations, using polysubstituted alkene derivatives to construct functionalized cyclic products remains challenging due to their significantly lower reactivity. This highlights key developments in stereoselective semi-intramolecular metal-catalyzed [(2+2)+1] and [(2+2)+2] carbocyclizations of 1,6-enynes containing 1,1-disubstituted alkenes, which produce cycloadducts with quaternary stereogenic centers.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, and Chemical Biology Center, Peking University, 38 Xueyuan Road, Beijing 100191, China.
Molecules
November 2024
State Key Laboratory of Environmental Chemistry and Eco-Toxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
A divergent total synthesis of bioactive, naturally occurring decanolides, pinolidoxin and bellidisin C, was accomplished by taking advantage of chiral templates -ribose and -malic acid. In particular, bellidisin C, which is the first total synthesis so far, was achieved through a cascade reaction of reductive elimination and nucleophilic addition in a one-pot process and a sodium-alkoxide-promoted intramolecular lactonization as the key steps.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry and Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of Catalysis and Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China.
Daphnimacropodines A-C are members of a small but structurally distinct subfamily of alkaloids. Their congested polycyclic skeletons, and two vicinal quaternary stereocenters, present significant synthetic challenges. This paper describes two stereoselective approaches to constructing the tricyclic core structures of daphnimacropodines, achieved through a straightforward Rh-catalyzed [4 + 3] cycloaddition using simple building blocks.
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