Facile Access to Cyclopropylboronates via Stereospecific Deborylative Cyclization: A Leaving Group‐Assisted Activation of Geminal Diborons

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(21)

Published: March 24, 2023

Herein we reported a transition metal-free deborylative cyclization strategy, based on which two routes have been developed, generating racemic and enantioenriched cyclopropylboronates. The of geminal-bis(boronates) bearing leaving group was highly diastereoselective, tolerating few functional groups applicable to heterocycles. When optically active epoxides were used as the starting materials, cyclopropylboronates could be efficiently prepared with >99 % stereospecificity. Mechanistic studies showed that at γ-position played crucial role significantly promoted activation gem-diboron moiety.

Language: Английский

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Ir‐Catalyzed Enantioselective Synthesis of gem‐Diborylalkenes Enabled by 1,2‐Boron Shift

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(32)

Published: June 15, 2023

Abstract Asymmetric cross‐couplings based on 1,2‐carbon migration from B‐ate complexes have been developed efficiently to access valuable organoboronates. However, enantioselective reactions triggered by 1,2‐boron shift remained be unaddressed synthetic challenge. Here, Ir‐catalyzed asymmetric allylic alkylation enabled was developed. In this reaction, we disclosed that excellent enantioselectivities were achieved through an interesting dynamic kinetic resolution (DKR) process of carbonates at the elevated temperature. Notably, highly (bis‐boryl)alkenes array diversifications versatile molecules. Extensive experimental and computational studies conducted elucidate reaction mechanism DKR clarify origin enantioselectivities.

Language: Английский

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Palladium‐Catalyzed Cascade Heck Coupling and Allylboration of Iododiboron Compounds via Diboryl Radicals

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(18)

Published: March 6, 2024

Geminal bis(boronates) are versatile synthetic building blocks in organic chemistry. The fact that they predominantly serve as nucleophiles the previous reports, however, has restrained their potential. Herein we disclose ambiphilic reactivity of α-halogenated geminal bis(boronates), which first catalytic utilization was accomplished by merging a formal Heck cross-coupling with highly diastereoselective allylboration aldehydes or imines, providing new avenue for rapid assembly polyfunctionalized boron-containing compounds. We demonstrated this cascade reaction is efficient and compatible various functional groups, wide range heterocycles. In contrast to classical Pd(0/II) scenario, mechanistic experiments DFT calculations have provided strong evidence cycle involving Pd(I)/diboryl carbon radical intermediates.

Language: Английский

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Photogeneration of α-Bimetalloid Radicals via Selective Activation of Multifunctional C1 Units

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(23), P. 15850 - 15859

Published: May 28, 2024

Light-driven strategies that enable the chemoselective activation of a specific bond in multifunctional systems are comparatively underexplored comparison to transition-metal-based technologies, yet desirable when considering controlled exploration chemical space. With current drive discover next-generation therapeutics, reaction design enables strategic incorporation an sp3 carbon center, containing multiple synthetic handles for subsequent space would be highly enabling. Here, we describe photoactivation ambiphilic C1 units generate α-bimetalloid radicals using only Lewis base and light source directly activate C–I bond. Interception these transient with various SOMOphiles rapid synthesis organic scaffolds (B, Si, Ge) orthogonal activation. In-depth theoretical mechanistic studies reveal prominent role 2,6-lutidine forming photoactive charge transfer complex stabilizing situ generated iodine radicals, as well influential boron p-orbital activation/weakening This simple efficient methodology enabled expedient access functionalized 3D frameworks can further derivatized available technologies C–B C–Si

Language: Английский

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Cobalt‐Catalyzed Diborylation of 1,1‐disubstituted Vinylarenes: A Practical Route to Branchedgem‐Bis(boryl)alkanes

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 57(6), P. 1654 - 1658

Published: Nov. 29, 2017

Abstract We report the first catalytic diborylation of 1,1‐disubstituted vinylarenes with pinacolborane using a cobalt catalyst generated from bench‐stable Co(acac) 2 and xantphos. A wide range underwent this transformation to produce corresponding gem ‐bis(boryl)alkanes in modest high yields. This cobalt‐catalyzed reaction can be readily conducted on gram scale without use dry box represents practical effective approach prepare branched ‐bis(boryl)alkanes.

Language: Английский

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A Coupling Approach for the Generation of α,α-Bis(enolate) Equivalents: Regioselective Synthesis of gem-Difunctionalized Ketones

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(6), P. 2036 - 2040

Published: Jan. 30, 2018

Regioselective α,α-difunctionalization adjacent to a ketone is significant synthetic challenge. Here, we present solution this problem through the transition-metal-free coupling of esters with geminal bis(boron) compounds. This forms an α,α-bis(enolate) equivalent which can be trapped electrophiles including alkyl halides and fluorinating agents. presents efficient, convergent strategy for synthesis unsymmetrical blocked ketones.

Language: Английский

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Cobalt‐Catalyzed Enantioselective Synthesis of Chiral gem‐Bis(boryl)alkanes

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(39), P. 12935 - 12939

Published: Aug. 16, 2018

We report an asymmetric synthesis of enantioenriched gem-bis(boryl)alkanes in enantioselective diborylation 1,1-disubstituted alkenes catalyzed by Co(acac)2 /(R)-DM-segphos. A range activated and unactivated underwent this the presence cyclooctene as a hydrogen acceptor, affording corresponding with high enantioselectivity. The synthetic utility these chiral organoboronate compounds was demonstrated through several stereospecific derivatizations sesquiterpene sesquiterpenoid natural products.

Language: Английский

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Sulfonate N‐Heterocyclic Carbene–Copper Complexes: Uniquely Effective Catalysts for Enantioselective Synthesis of C−C, C−B, C−H, and C−Si Bonds

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(48), P. 21304 - 21359

Published: May 4, 2020

A copper-based complex that contains a sulfonate N-heterocyclic carbene ligand was first reported 15 years ago. Since then, these organometallic entities have proven to be uniquely effective in catalyzing an assortment of enantioselective transformations, including allylic substitutions, conjugate additions, proto-boryl additions alkenes, boryl and silyl hydride-allyl alkenyl boronates, boron-containing allyl moieties N-H ketimines. In this review article, we detail the shortcomings state-of-the-art fueled development air stable class, members which can prepared on multigram scale. For each reaction type, when relevant, prior art at time advance involving NHC-Cu catalysts and/or subsequent key developments are briefly analyzed, relevance efficient total or formal synthesis biologically active molecules is underscored. Mechanistic analysis structural attributes responsible for their ability facilitate transformations with high efficiency as well regio- enantioselectivity detailed. This several formerly undisclosed methodological advances mechanistic analyses, latter constitute revision previously proposals.

Language: Английский

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Diastereo- and Enantioselective Synthesis of Homoallylic Amines Bearing Quaternary Carbon Centers

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(4), P. 1704 - 1709

Published: Jan. 14, 2020

A Cu-catalyzed method for the efficient enantio- and diastereoselective synthesis of chiral homoallylic amines bearing a quaternary carbon an alkenylboron is disclosed. Transformations are promoted by readily prepared (phosphoramidite)–Cu complex involve bench-stable γ,γ-disubstituted allyldiborons benzyl imines; products obtained in up to 82% yield, >20:1 dr, >99:1 er. Reactions proceed via stereodefined boron-stabilized allylic Cu species formed enantioselective transmetalation. Utility 1-amino-3-alkenylboronate highlighted variety synthetic transformations.

Language: Английский

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Recent developments in the asymmetric synthesis and functionalization of symmetrical and unsymmetricalgem-diborylalkanes

Organic Chemistry Frontiers, Journal Year: 2021, Volume and Issue: 9(3), P. 838 - 852

Published: Nov. 16, 2021

gem -Diborylalkanes are an important class of organoboron compounds as they function a key building block in organic synthesis. This review summarizes recent developments the enantioselective synthesis -diborylalkanes and application asymmetric

Language: Английский

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