By employing an easily available, exceptionally simple sulfur-olefin ligand, a highly enantioselective rhodium-catalyzed arylation of cyclic N-sulfonyl α-ketimino esters with arylboronic acids has been developed. The reaction allows facile access to a wide range of α,α-gem-diaryl substituted chiral amino esters in excellent yields with extremely high enantioselectivities (uniformly 98-99% ee). The synthetic utility of this approach was highlighted by the efficient synthesis of a series of interesting molecules including unique chiral spirocycles bearing 2,3-dihydrobenzofuran and 1H-isoindole skeletons.
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http://dx.doi.org/10.1039/c8ob00840j | DOI Listing |
J Am Chem Soc
January 2025
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
Taming highly enolizable aldehydes for catalytic asymmetric C-C coupling with nucleophiles remains an elusive challenge compared to widely explored simple alkyl or aryl aldehydes. Herein, we use ThDP-dependent enzymes to realize the direct C-C coupling of highly enolizable 2-phosphonate aldehydes with in situ-generated dynamically reversible nucleophiles (acyl anions). Unlike NHC-mediated reactions that yield complex mixtures of multiple adducts, our enzymatic process selectively produces biologically active β-hydroxy phosphonates with high yields (up to 95%) and excellent enantioselectivities (up to 99% ee).
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Direct synthesis of enantioenriched scaffolds with multiple adjacent stereocenters remains an important yet challenging task. Herein, we describe a highly diastereo- and enantioselective Cu-catalyzed alkylboration of cyclopropenes, with less reactive alkyl iodides as electrophiles, for the efficient synthesis of -substituted borylated cyclopropanes bearing three consecutive stereocenters. This protocol features mild conditions, a broad substrate scope, and good functional group tolerance, affording an array of chiral borylated cyclopropanes in good to high yields with excellent diastereo- and enantioselectivities.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States.
The development of catalytic methods for the synthesis of enantiopure saturated heterocycles has been a long-standing challenge in asymmetric catalysis. We describe the first highly enantioselective palladium-catalyzed βC(sp)-H arylation and olefination of lactams for the preparation of various chiral N-heterocycles bearing quaternary carbon centers. The presence of strongly electron-withdrawing groups on the chiral bifunctional MPAThio ligand is crucial to the reactivity of weakly coordinating lactams.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Institute of Organic Chemistry, University of Leipzig, 04103 Leipzig, Germany.
The enantioselective synthesis of 1,4-dicarbonyl compounds continues to pose a significant challenge in organic synthesis, and a catalytic process which generates two adjacent stereogenic centers with full stereochemical control is lacking until now. The 1,4-relationship of the functional groups requires an Umpolung strategy as one of the α-carbonyl positions has to be inverted into an electrophilic center to react with a normal enolate. We report herein the highly enantio- and diastereoselective addition of silyl ketene acetals toward electrophilic 1-azaallyl cations to furnish chiral 4-hydrazonoesters, which are masked 1,4-dicarbonyl compounds.
View Article and Find Full Text PDFBiotechnol Notes
December 2024
Centre for Molecular Biology, Central University of Jammu, Rahya Suchani (Bagla), Jammu & Kashmir, India.
The amidases (EC 3.5.1.
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