A new enantioselective Michael addition between 3-(3-hydroxy-1-pyrazol-1-yl)oxindole, a new synthon generated from isatin ,-cyclic azomethine imine 1,3-dipole, and β-nitrostyrene has been disclosed. A series of chiral 3-(3-oxo-2,3-dihydro-1-pyrazol-1-yl) disubstituted oxindoles were obtained in excellent results (up to 97% yield, up to 94% ee) with moderate to good diastereoselectivities (up to 4.3:1 dr).
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http://dx.doi.org/10.1021/acs.joc.9b03337 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Changchun Institute of Applied Chemistry Chinese Academy of Sciences: Chang Chun Institute of Applied Chemistry Chinese Academy of Sciences, Jilin Province Key Lab of Green Chemistry and Process, CHINA.
A modular approach was developed for the first catalytic asymmetric total syntheses of naturally occurring C30 terpene quinone methides and their non-natural stereoisomers, which feature the presence of an unprecedented spiro[4.4]nonane-containing 6-6-6-5-5-3 hexacyclic skeleton. Resting on a chiral phosphinamide-catalyzed enantioselective reduction of 2,2-disubstituted cyclohexane-1,3-dione, a concise route for the synthesis of enantioenriched 6-6 bicyclic fragment was developed.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
EPFL: Ecole Polytechnique Federale de Lausanne, Institute of Chemical Sciences and Engineering, EPFL-ISIC-LSCI, BCH 3305, 1015, Lausanne, SWITZERLAND.
Artificial metalloenzymes (ArMs) enable the integration of abiotic cofactors within a native protein scaffold, allowing for non-natural catalytic activities. Previous ArMs, however, have primarily relied on single cofactor systems, limiting them to only one catalytic function. Here we present an approach to construct ArMs embedding two catalytic cofactors based on the biotin-streptavidin technology.
View Article and Find Full Text PDFChemistry
December 2024
Department of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
We present a comprehensive account on the evolution of a synthetic platform for a subfamily of ent-pimaranes. For the most complex member, norflickinflimiod C, five distinct strategies relying on either cationic or radical polyene cyclizations to construct the requisite tricyclic carbon scaffold were explored. Insights from early and late stage oxidative and reductive dearomatization studies ultimately led to a mild, rhodium-catalyzed arene hydrogenation for the final synthetic route.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047, United States.
We show the first examples of enantioselective cyclization reactions of tethered sulfamates onto pendant α,β-unsaturated esters, ketones, and thioesters. This reaction is promoted by a new chiral bifunctional guanidine catalyst and is operationally very simple. A variety of primary sulfamates and sulfamides were examined, and in many cases, products were delivered in excellent yields and enantiomeric ratios.
View Article and Find Full Text PDFJ Org Chem
December 2024
Institute and State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, P. R. China.
An asymmetric tandem esterification/Michael addition reaction of β-keto acylpyrazoles with -hydroxychalcones has been established under the catalysis of a bifunctional squaramide-tertiary amine. A wide variety of biorelevant 3,4-dihydrocoumarin derivatives were generally obtained in high yields (up to 93%) with excellent diastereo- and enantioselectivities (>19:1 dr, up to 93% ee) under mild reaction conditions. This reaction represents the successful application of β-keto acylpyrazoles as 2C building blocks in catalytic asymmetric cyclizations.
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