Catalytic Chemo- and Enantioselective Transformations of gem-Diborylalkanes and (Diborylmethyl)metallic Species

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(20), P. 3917 - 3929

Published: Oct. 6, 2021

ConspectusChemo- and stereoselective transformations of polyborylalkanes are powerful efficient methods to access optically active molecules with greater complexity diversity through programmed synthetic design. Among the various polyborylalkanes, gem-diborylalkanes have attracted much attention in organic chemistry as versatile handles. The notable advantage lies their ability generate two key intermediates, α-borylalkyl anions (gem-diborylalkyl) anions. These different intermediates can be applied enantioselective reactions rapidly a diverse set enantioenriched organoboron compounds, which further manipulated chiral molecule libraries via stereospecific C(sp3)–B bond transformations.In this Account, we summarize our recent contributions development catalytic chemo- using nucleophiles, categorized follows: (1) copper-catalyzed coupling electrophiles (2) design synthesis (diborylmethyl)metallic species applications reactions. Since Shibata Endo reported Pd-catalyzed chemoselective Suzuki–Miyaura cross-coupling organohalides 2014, Morken Hall subsequently developed first analogous TADDOL-derived phosphoramidite supporting ligand palladium catalyst. This discovery sparked interest electrophiles. Our initial studies focused on generating (α-borylmethyl)copper by enantiotopic-group-selective transmetalation copper complexes aldimines ketimines afford syn-β-aminoboronate esters excellent enantio- diastereoselectivity. Moreover, allylation that proceeded reaction situ-generated (α-borylalkyl)copper allyl bromides. Mechanistic investigations revealed between complex occurred open transition state rather than closed state, thereby effectively species. We also utilized such (diborylmethyl)silanes (diborylmethyl)zinc halides succeeded developing aryl iodides benzylic 1,1-silylboronate esters, could used for consecutive molecules. In addition, synthesized time isolated (diborylmethyl)lithium zinc(II) utilization bearing center at β-position an iridium-catalyzed allylic substitution process. addition research efforts, include other groups. hope Account will draw community gem-diboryl compounds provide guiding principles future compounds.

Language: Английский

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Nickel-Catalyzed Regio- and Enantioselective Borylative Coupling of Terminal Alkenes with Alkyl Halides Enabled by an Anionic Bisoxazoline Ligand

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(25), P. 13603 - 13614

Published: June 6, 2023

Chiral boronic esters are a class of versatile building blocks. We describe herein an asymmetric nickel-catalyzed borylative coupling terminal alkenes with nonactivated alkyl halides. The success this reaction is ascribed to the application chiral anionic bisoxazoline ligand. This study provides three-component strategy access α- and β-stereogenic from easily accessible starting materials. protocol characterized by mild conditions, wide substrate scope high regio- enantioselectivity. also showcase value method in simplifying synthesis several drug molecules. Mechanistic studies suggest that generation enantioenriched bearing α-stereogenic center results stereoconvergent process, while enantioselectivity-controlling step β-stereocenter switched olefin migratory insertion due coordination ester group.

Language: Английский

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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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Enantioselective synthesis of multifunctional alkylboronates via N-heterocyclic carbene–nickel-catalysed carboboration of alkenes

Nature Synthesis, Journal Year: 2024, Volume and Issue: 3(5), P. 633 - 642

Published: March 7, 2024

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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Asymmetric Synthesis of Chiral 1,2‐Bis(Boronic) Esters Featuring Acyclic, Non‐Adjacent 1,3‐Stereocenters

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(5)

Published: Dec. 15, 2023

The construction of acyclic, non-adjacent 1,3-stereogenic centers, prevalent motifs in drugs and bioactive molecules, has been a long-standing synthetic challenge due to acyclic nucleophiles being distant from the chiral environment. In this study, we successfully synthesized highly valuable 1,2-bis(boronic) esters featuring nonadjacent 1,3-stereocenters. Notably, reaction selectively produces migratory coupling products rather than alternative deborylative allylation or direct byproducts. This approach introduces new activation mode for selective transformations gem-diborylmethane asymmetric catalysis. Additionally, found that other gem-diborylalkanes, previously challenging steric hindrance, also participated reaction. incorporation 1,2-bis(boryl)alkenes facilitated diversification alkenyl two boron moieties our target compounds, thereby enabling access broad array versatile molecules. DFT calculations were performed elucidate mechanism shed light on factors responsible observed excellent enantioselectivity diastereoselectivity. These determined arise ligand-substrate repulsions syn-addition transition state.

Language: Английский

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A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(4)

Published: Dec. 8, 2023

Abstract General methods for the preparation of geminal bis(boronates) are great interest due to their widespread applications in organic synthesis. While terminal gem ‐diboron compounds readily accessible, construction sterically encumbered, internal analogues has remained a prominent challenge. Herein, we report formal umpolung strategy access these valuable building blocks. The available 1,1‐diborylalkanes were first converted into corresponding α‐halogenated derivatives, which then serve as electrophilic components, undergoing substitution with diverse array nucleophiles form series C−C, C−O, C−S, and C−N bonds. This protocol features good tolerance steric hindrance wide variety functional groups heterocycles. Notably, this can also be extended synthesis diaryl compounds, therefore providing general approach various types bis(boronates).

Language: Английский

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