Modular Organoboron Catalysts Enable Transformations with Unprecedented Reactivity

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(23), P. 4434 - 4448

Published: Nov. 21, 2021

ConspectusElectron-deficient boron-based catalysts with metal-free but metallomimetic characteristics provide a versatile platform for chemical transformations. However, their catalytic performance is usually lower than that of the corresponding metal-based catalysts. Furthermore, many elaborate organoboron compounds are produced via time-consuming multistep syntheses low yields, presenting formidable challenge large-scale applications these Given this context, development combined advantages high efficiency and easy preparation critical importance.Therefore, we envisioned construction dynamic Lewis multicore system (DLMCS) by integrating acidic boron center(s) basic ammonium salt in one molecule would be particularly efficient on-demand because intramolecular synergistic effect. This Account summarizes our recent efforts developing modular unprecedented activities several A series mono-, di-, tri-, tetranuclear was readily designed prepared nearly quantitative yields over two steps using commercially available feedstocks. Notably, can modularly tailored fine control electrophilic property center(s), electronic steric effects electropositive cation, linker length between center number centers, nucleophilic anion. design allows systematic manipulation reactivity efficacy catalysts, thus optimizing suitable These include coupling CO2 epoxides, copolymerization ring-opening polymerization (ROP) (ROCOP) epoxides cyclic anhydrides.The utilization mononuclear provided turnover frequency 11050 h-1 CO2/propylene oxide reaction, an 5.0 kg polymer/g catalyst cyclohexene oxide, record-breaking 7.4 ROCOP anhydrides. 56500 observed at loading 10 ppm ROP dinuclear The realized previously intractable task epichlorohydrin, producing poly(chloropropylene carbonate) highest molecular weight 36.5 kg/mol reported to date.Furthermore, study revealed interaction multicore, is, effect quaternary salt, plays key role mediating activity selectivity. based on investigations crystal structures intermediates, reaction kinetics, density functional theory calculations. tactics presented should inspire more advanced designs.

Language: Английский

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Alkyl borane-mediated metal-free ring-opening (co)polymerizations of oxygenated monomers

Progress in Polymer Science, Journal Year: 2022, Volume and Issue: 136, P. 101644 - 101644

Published: Dec. 30, 2022

Language: Английский

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Synthesis of axially chiral alkenylboronates through combined copper- and palladium-catalysed atroposelective arylboration of alkynes

Nature Synthesis, Journal Year: 2023, Volume and Issue: 2(2), P. 140 - 151

Published: Jan. 5, 2023

Language: Английский

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Ni-catalysed assembly of axially chiral alkenes from alkynyl tetracoordinate borons via 1,3-metallate shift

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(1), P. 42 - 53

Published: Jan. 1, 2024

Language: Английский

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Cu-Catalyzed Diastereo- and Enantioselective Synthesis of Borylated Cyclopropanes with Three Contiguous Stereocenters

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 17, 2025

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 cyclopropenes, less reactive alkyl iodides as electrophiles, for the efficient tetra-substituted borylated cyclopropanes bearing three consecutive stereocenters. This protocol features mild conditions, broad substrate scope, good functional group tolerance, affording array chiral in to high yields excellent enantioselectivities. Detailed mechanistic experiments kinetic studies were conducted elucidate reaction pathway rate-determining step reaction. DFT calculations revealed that π···π stacking interaction between phenyl groups on phosphorus ligand, along smaller distortion CuL-Bpin part, contributed The synthetic utility was showcased by facile some valuable centers.

Language: Английский

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Enantioselective Cobalt-Catalyzed Cascade Hydrosilylation and Hydroboration of Alkynes to Access Enantioenriched 1,1-Silylboryl Alkanes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(33), P. 13124 - 13134

Published: Aug. 12, 2021

Enantioenriched 1,1-silylboryl alkanes possess silyl and boryl groups that are both connected to the same stereogenic carbon center at well-defined orientations. As these chiral multifunctionalized compounds potentially offer two synthetic handles, they highly valued building blocks in asymmetric synthesis as well medicinal chemistry. Despite potential usefulness, efficient approaches for their preparation scarce. Seeking address this deficiency, an enantioselective cobalt-catalyzed hydrosilylation/hydroboration cascade of terminal alkynes has been realized. This protocol constitutes impressive case chemo-, regio-, stereoselectivity wherein different hydrofunctionalization events exquisitely controlled by a single set metal catalyst ligand, operation which would usually require separate catalytic systems. Downstream transformations enantioenriched 1,1-silyboryl led various valuable compounds. Mechanistic studies suggest present reaction undergoes regioselective stereocontrolled sequential hydrosilylation hydroboration processes.

Language: Английский

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Catalytic Enantioselective Construction of Chiroptical Boron-Stereogenic Compounds

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(39), P. 16302 - 16310

Published: Sept. 27, 2021

The construction of main group heteroatom-stereogenic compounds is great importance due to their intriguing chemical, physical, biological, and stereoelectronic properties. Despite that organoboron are widely used in organic chemistry, the creation a tetrahedral boron-stereogenic center one enantiomeric form remains highly challenging. Given labile nature ligands attached tetracoordinate boron atom, only handful enantioenriched have been reported via resolution or chiral substrate-induced diastereoselective approach. To date catalytic asymmetric synthesis has remained unknown. Here, we demonstrate first enantioselective an copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. This CuAAC reaction not gives access wide range novel functionalized heterocycles high yields with good excellent enantioselectivities but also produces optically active terminal alkyne triazole moieties various potential application prospects. Further transformation delivers several complex heterocyclic entities bearing centers without loss enantiopurity. Moreover, X-ray structure, barrier racemization, HOMO/LUMO gap selected investigated. Notably, these N,N π-conjugated exhibit bright fluorescence. optical properties, including circular dichroism, quantum yield, polarized luminescence spectroscopies, examined. These features expand chemical space chiroptical boron-based dye platform, which could applications optoelectronic materials.

Language: Английский

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Catalysis with Diboron(4)/Pyridine: Application to the Broad-Scope [3 + 2] Cycloaddition of Cyclopropanes and Alkenes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(19), P. 8870 - 8882

Published: May 9, 2022

In contrast to the extensive but non-recyclable use of tetraalkoxydiboron(4) compounds as stoichiometric reagents in diverse reactions, this article reports an atom-economical reaction using a commercial diboron(4) catalyst. The key success was designing catalytic cycle for radical [3 + 2] cycloaddition involving pyridine cocatalyst generate from catalyst and reversibly mediate transfer boronyl radicals. comparison with known transition metal-based catalysts, current features not only metal-free conditions, inexpensive stable simple operation also remarkably broadened substrate scope. particular, previously unusable cyclopropyl ketones without activating group and/or alkenes 1,2-disubstitution 1,1,2-trisubstitution patterns were successfully used first time. Consequently, challenging cyclopentane various levels substitution (65 examples, 57 new products, up six substituents at all five ring atoms) readily prepared generally high excellent yield diastereoselectivity. applied concise formal synthesis anti-obesity drug building natural product-like complex bridged or spirocyclic compounds. Mechanistic experiments computational investigation support proposed relay catalysis featuring pyridine-assisted Overall, work demonstrates approach catalysts may lead development new, green, efficient metal-like boron-catalyzed organic reactions.

Language: Английский

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Mechanism-Inspired Upgradation of Phosphonium-Containing Organoboron Catalysts for Epoxide-Involved Copolymerization and Homopolymerization

Macromolecules, Journal Year: 2022, Volume and Issue: 55(15), P. 6443 - 6452

Published: July 14, 2022

The dynamic Lewis multicore system (DLMCS) which integrates the acidic boron center(s) and an ammonium salt in one molecule has shown good catalytic performance polymer synthesis. Inspired by insightful intramolecular cation assisted mechanism, herein, we communicated a superior organoboron replacing nitrogen atom with phosphorus atom. upgraded mono-, di-, trinuclear catalysts show significantly improved heat resistance for versatile epoxide-involved transformations, including ring-opening copolymerization of epoxides cyclic anhydrides, CO2 epoxides, polymerization epoxides. 11B NMR, single-crystal X-ray diffraction, DFT results imply that onium led to effective epoxide activation nucleophilic attack counterion on activated epoxide, remarkably shortened initiation period accelerated chain expansion, resulting obvious improvement activity. phosphonium-containing combined mechanism study understanding would be instructive designing advanced metal-free catalysts.

Language: Английский

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Ni-Catalyzed Radical-Promoted Defluoroalkylborylation of Trifluoromethyl Alkenes To Access gem-Difluorohomoallylic Boronates

Organic Letters, Journal Year: 2022, Volume and Issue: 24(12), P. 2446 - 2451

Published: March 21, 2022

gem-Difluoroalkenyl boronates are attractive synthons for constructing diverse gem-difluoroalkenes and organoboron compounds. However, the strategies construction of gem-difluorohomoallyl has scarcely been described. Herein, we develop an efficient protocol gem-difluorohomoallylic through a Ni-catalyzed radical-promoted defluoroalkylborylation α-trifluoromethyl alkenes with α-haloboronates under mild conditions. This reaction features broad substrate scope good functional group tolerance transformations.

Language: Английский

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