A series of 1,3-disubstituted pyrrolo[2,3-b]quinoxalines has been designed for the potential inhibition of PDE4 without inhibiting luciferase. A ligand/PTC (phase transfer catalyst) free intramolecular Heck cyclization strategy was used to prepare these compounds, some of which showed significant inhibition of PDE4B (IC50≈ 5-14 μM) and growth inhibition of oral cancer cells (CAL 27) but not inhibition of luciferase in vitro. They also showed acceptable safety profiles but no apoptosis in zebrafish embryos.
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http://dx.doi.org/10.1039/c3ob41504j | DOI Listing |
Org 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.
View Article and Find Full Text PDFWe report the first asymmetric total synthesis of recently isolated heterodimeric alkaloids, narcipavlines A (1a) and B (1b), and narcikachnines A (2a) and B (2b), thereby confirming their absolute stereochemistry. These alkaloids showcase a unique heterodimeric structure, amalgamating two distinct types of alkaloids: the -hydrodibenzofuran containing tetracyclic galantamine core (6a) and the galanthindole core (7) featuring a biaryl axis. The presence of this biaryl axis, coupled with the substantial galantamine core (6a) at the substituents, imposes constraints on free rotation around the C-C axis, resulting in atropisomerism, an exceedingly rare phenomenon in nature.
View Article and Find Full Text PDFOrg Lett
December 2024
Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
A Pd-catalyzed asymmetric Heck cascade reaction involving the intramolecular carbopalladation of unsaturated hydrocarbons, followed by nucleophilic trapping of the resulting palladium species, is a powerful approach for constructing chiral -heterocycles. However, the use of prochiral nucleophiles in these reactions remains significantly underexplored. Herein, we report a novel Pd/Cu catalytic system for the asymmetric cascade Heck/Tsuji-Trost reaction of allenamides and aldimine esters.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Chemical Engineering, State Key Laboratory Breeding Base of Green Chemical Synthesis Technology, Zhejiang University of Technology, Chaowang Road 18#, Hangzhou 310014, P. R. China.
Herein, a cobalt-catalyzed intramolecular enantioselective reductive Heck reaction is disclosed. Starting from --iodoaryl-2-(trifluoromethyl)acrylamides, a plethora of chiral oxindoles bearing trifluoromethylated quaternary stereogenic centers at the C3-position are achieved in moderate to good yields (up to 88% yield) and good to excellent enantioselectivities (up to 94% ee) by employing zinc/silane as reducing agent. Other than the trifluoromethyl group, a number of chiral oxindoles bearing alkyl, aryl, and ester groups at C3-position were also obtained albeit in relatively lower enantioselectivities (68-78% ee).
View Article and Find Full Text PDFACS Omega
November 2024
Faculty of Sciences of Bizerte, LR18ES11, Laboratory of Hetero-Organic Compounds and Nanostructured Materials, University of Carthage, Bizerte 7021, Tunisia.
Here, we report the intramolecular Heck cross-coupling of 1,3-dienylphosphonates, affording unique and regioselective access to unprecedented benzofused phostone and phostam derivatives. The reactions proceeded under operationally simple and mild conditions with a wide substrate scope.
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