Alkyl Radical Generation from Alkylboronic Pinacol Esters through Substitution with Aminyl Radicals

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(16), P. 8770 - 8775

Published: April 14, 2023

Alkylboronic pinacol esters (APEs) are highly versatile reagents in organic synthesis. However, the direct generation of alkyl radicals from commonly used, bench-stable APEs has not been well explored. In this communication, radical through reaction with aminyl is reported. The readily generated by visible-light-induced homolytic cleavage N-N bond N-nitrosamines, and C occurs nucleohomolytic substitution at boron. As an application, efficient photochemical alkyloximation alkenes N-nitrosamines under mild conditions presented. A wide range primary, secondary, tertiary engage transformation that easily scaled up.

Language: Английский

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Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

Organometallics, Journal Year: 2023, Volume and Issue: 42(14), P. 1746 - 1758

Published: March 15, 2023

The conjugated bis-guanidinate (CBG) supported zinc hydride, [{LZnH}2; L = {(ArHN)(ArN)-C═N–C═(NAr)(NHAr); Ar 2,6-Et2-C6H3}] (1) (pre)-catalyzed addition of E–H (E B, C, N, and O) to carbodiimides is presented. Compound 1 catalyzed the reduction with pinacolborane (HBpin), terminal alkynes, primary amines, alcohols, gave a series N-boryl formamidines, propiolamidines, guanidines, isoureas high conversions. All these reactions display good tolerance functional groups. These proceeded through active catalysts intermediate amidinate (Zn-1, Zn-1′, Zn-3), alkynyl (Zn-2, Zn-2′), anilide (Zn-4), alkoxide (Zn-5) complexes, which have been characterized by multinuclear NMR HRMS analyses. Moreover, compounds Zn-2′, Zn-4, Zn-5 were confirmed single-crystal X-ray diffraction studies. Complete catalytic cycles proposed based on well-defined intermediates stoichiometric experiments.

Language: Английский

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Deboronative functionalization of alkylboron species via a radical-transfer strategy

Chemical Science, Journal Year: 2024, Volume and Issue: 15(35), P. 14241 - 14247

Published: Jan. 1, 2024

We describe a method for activating C–B bonds by nitrogen- or oxygen-radical transfer that is applicable to alkylboronic acids and esters.

Language: Английский

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Photochemical C–H Borylation in Organic Synthesis

ACS Catalysis, Journal Year: 2025, Volume and Issue: 15(3), P. 1753 - 1770

Published: Jan. 16, 2025

Although C–H bond functionalization has been extensively studied since its discovery in 1955, the borylation of organic compounds by activating bonds only became popular valuable Hartwig 1995 who considered a wider application these transformations synthetic chemistry. For borylation, catalytic activation this generally low-reactivity can be performed many ways. Among approaches reported are use and stoichiometric reagents, thermal activation, photochemical suitable substrates. Iridium-, ruthenium-, rhodium-based protocols using have played crucial role toward establishment area. Photochemical though, scarcely explored despite fact that it represents comparably environmentally benign protocol light as renewable energy source. In literature survey, we highlight recent developments from initial inception up to latest advancements.

Language: Английский

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Fluorenyl-tethered N-heterocyclic carbene: An effective ancillary support for heteroleptic magnesium organometallics

Polyhedron, Journal Year: 2024, Volume and Issue: 251, P. 116849 - 116849

Published: Jan. 21, 2024

Language: Английский

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Synthesis, Characterization, and Reactivity of Aminotroponiminate-Based Difluoroboranes: A Pathway toward Bore(boro)nium Cations

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: May 10, 2025

Aminotroponiminates (ATIs), a well-known monoanionic bidentate ligand, display wide range of coordination chemistry. To exploit their electronic and steric factors in achieving boron cations, series symmetrical, unsymmetrical, bis(ATI) borane complexes [(C7H5)(NiPr)2BF2] (3a), [(C7H5)(NtBu)2BF2] (3b), [(C7H5)(NiBu)2BF2] (3c), [(C7H5)(NiBu)(NtBu)BF2] (3d), [(C7H5)(NiPr)(NCH2)BF2]2 (3e) were synthesized this work. All the ATI are highly blue luminescent solution, fluorescence decay time was recorded DCM. The observed found to exist between 1.7 2.8 ns. Complexes 3a 3b when treated with trimethylsilyl triflate (TMS-OTf) enabled isolation tricoordinated borenium cations [(C7H5)(NiPr)2BOH]+ (4a) [(C7H5)(NtBu)2BOH]+ (4b), respectively. Interestingly, reaction 3e TMS-OTf resulted dication 4e which boronium bridged via an oxygen atom seven-membered ring scaffold. boranes well characterized by various spectroscopic techniques solution X-ray structure diffraction analysis solid state. Further, theoretical calculations using density functional theory (DFT) conducted understand bonding scenario these complexes.

Language: Английский

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Visible-Light-Induced trans-Hydroboration of Diaryl Alkynes Utilizing Excited State of Borate Complexes

Organic Letters, Journal Year: 2024, Volume and Issue: 26(11), P. 2180 - 2185

Published: March 11, 2024

We have developed visible-light-induced trans-hydroboration of diaryl alkynes via direct photoexcitation in-situ-generated diboron complexes, affording previously elusive (E)-1,2-diaryl-vinylboronates with high stereoselectivity. Experimental, spectroscopic, and theoretical mechanistic studies revealed that the triplet-state borate complex facilitates B–B bond cleavage desired C–B formation. This methodology does not require any catalyst is operationally simple. The highly borylated 1,2-diaryl alkenes [1-(2-borylphenyl)vinyl)boronates] are shown to be useful as building blocks.

Language: Английский

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Magnesium halide-catalyzed hydroboration of isocyanates and ketones

Organic & Biomolecular Chemistry, Journal Year: 2023, Volume and Issue: 21(17), P. 3628 - 3635

Published: Jan. 1, 2023

Alkaline-earth metals have attracted increasing attention because they are cheap, Earth abundant and environmentally friendly, gradually become inexpensive sustainable alternatives to traditional precious transition metal catalysts in many organic reactions. Recently, the hydroboration of unsaturated substrates has been extensively investigated. However, reports on alkaline-earth catalyzed isocyanates ketones rare. Herein, we report that simple, commercially available, air-stable magnesium halides successfully employed as highly efficient ketones. Various boronate products were obtained high yields with low catalyst loading under mild conditions.

Language: Английский

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Metal-free C–H Borylation and Hydroboration of Indoles

ACS Omega, Journal Year: 2023, Volume and Issue: 8(41), P. 37623 - 37640

Published: Oct. 2, 2023

The C–H borylation and hydroboration reactions have emerged as promising synthetic tools to construct organoboron compounds. Organoboron compounds of N-heterocycles, particularly indole derivatives, found widespread application in a variety fields. As result, considerable advancement the area indoles was observed last few decades. Among various methods applied, metal-free approach has received special attention. This mini-review discusses recent progress under conditions, their scope, brief mechanistic studies.

Language: Английский

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Catalyst-Free α-trans-Selective Hydroboration and (E)-Selective Deuterated Semihydrogenation of Alkynyl Sulfones

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(12), P. 8326 - 8333

Published: May 31, 2024

Here, we present a straightforward α-trans-selective hydroboration of alkynyl sulfones with NHC–boranes without the need for catalyst. This reaction is compatible wide range substrates efficiently producing structurally diverse α-borylated vinyl in satisfactory yields. The hydride transfer from NHC–borane 2a to triflone 1b studied by density functional theory (DFT) calculations trans-hydroboration. Moreover, regiodivergent deuterated semihydrogenation triflones has also been developed using D2O as deuterium source. A variety diversity-oriented D-containing were prepared good excellent yields incorporation ratios. Synthetic manipulations products are achieved conversion into valuable molecules, indicating utility this protocol.

Language: Английский

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