Science
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Published: December 2022
From the preparation of pharmaceuticals to enzymatic construction of natural products, carbocations are central to molecular synthesis. Although these reactive intermediates are engaged in stereoselective processes in nature, exerting enantiocontrol over carbocations with synthetic catalysts remains challenging. Many resonance-stabilized tricoordinated carbocations, such as iminium and oxocarbenium ions, have been applied in catalytic enantioselective reactions. However, their dicoordinated counterparts (aryl and vinyl carbocations) have not, despite their emerging utility in chemical synthesis. We report the discovery of a highly enantioselective vinyl carbocation carbon-hydrogen (C-H) insertion reaction enabled by imidodiphosphorimidate organocatalysts. Active site confinement featured in this catalyst class not only enables effective enantiocontrol but also expands the scope of vinyl cation C-H insertion chemistry, which broadens the utility of this transition metal-free C(sp)-H functionalization platform.
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http://dx.doi.org/10.1126/science.ade5320 | DOI Listing |
Inorg Chem
January 2025
Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan.
The chemical reactivity between benzene and the "naked" acyclic carbene-like (G13X) species, having two bulky N-heterocyclic boryloxy ligands at the Group 13 center, was theoretically assessed using density functional theory computations. Our theoretical studies show that (BX) preferentially undergoes C-H bond insertion with benzene, both kinetically and thermodynamically, whereas the (AlX) analogue favors a reversible [4 + 1] cycloaddition. Conversely, the heavier carbene analogues ((GaX), (InX), and (TlX)) are not expected to engage in a reaction with benzene.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Photochemistry-based silica formation offers a pathway toward energy-efficient and controlled fabrication processes. While the transformation of poly(dimethylsiloxane) (PDMS) to silica (often referred to as SiO due to incomplete conversion) under deep ultraviolet (DUV) irradiation in the presence of oxygen/ozone has experimentally been validated, the detailed mechanism remains elusive. This study demonstrates the underlying molecular-level mechanism of PDMS-to-silica conversion using density functional theory (DFT) calculations.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States.
Monoanionic, bidentate-auxiliary-directed, cobalt-catalyzed C-H bond functionalization has become a very useful tool in organic synthesis. A comprehensive investigation into isolated organometallic intermediates and their reactivity within the catalytic cycle is lacking. We report here mechanistic studies of cobalt-catalyzed, aminoquinoline-directed C(sp)-H bond functionalization.
View Article and Find Full Text PDFJ Org Chem
January 2025
State Key Laboratory of Chemical Resource Engineering, Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China.
2-Hydroxyl/acetoxy-3-nitroindoles are directly and efficiently prepared in good to excellent yields from diazo(nitro)acetanilides under the catalysis of Cu(MeCN)PF in DCM through an intramolecular aromatic C-H insertion or followed by acetylation. 2-Hydroxyl-3-nitroindoles can be further transformed to 3-halo-3-nitroindolin-2-ones and 3-alkanamidoindolin-2-ones readily. All of them are important synthetic building blocks for construction of indole derivatives.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
University of Melbourne, School of Chemistry, 30 Flemington Rd., VIC 3095, Parkville, AUSTRALIA.
Palladium(II)-catalyzed C-H functionalization has attracted considerable attention as a pathway to late-stage modification of peptides. Herein, we report the Pd-catalyzed C(sp3)-H arylation of peptides directed by an amidoxime ether, which can be easily incorporated into peptides at any amide bond. Site- and stereoselective arylation of peptides has been achieved, including an unprecedented example of C-H arylation of an internal residue.
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