Merging Ketyl Radical Chemistry and Allylboration via Strain Release: One-Pot Multicomponent Access to Sterically Congested Ketone-Functionalized Organoborons

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: March 17, 2025

Ketyl radical-mediated ring opening and [2σ+2π] cycloaddition of cyclopropyl ketones (CPKs) with alkynes typically require activation by alkyl, aryl, or carbonyl groups yielding cyclopentenes having one two non-adjacent stereocenters. We developed a one-pot multicomponent reaction diboryl-activated CPKs aldehydes that merges ketyl radical chemistry allylboration. This method enabled highly diastereoselective access to densely functionalized featuring homoallylic alcohol, ketone, alkenyl boronate motifs on adjacent quaternary, tertiary, secondary stereogenic centers. Additionally, diboryl also allowed the synthesis rare ketone-functionalized γ,γ-disubstituted allylic diborons.

Language: Английский

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Alkene Isomerization through Allylmetals as a Strategic Tool in Stereoselective Synthesis

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(10), P. 5793 - 5804

Published: April 13, 2020

The positional isomerization of alkenes is a well-known process mediated by various transition metal complexes. Nevertheless, systems which isomerize with complete regio- and stereoselectivity are rare. Most reported cases proceed through 1,3-hydrogen shift (allyl) mechanisms, rather than the generally more common 1,2-hydride (alkyl) mechanism, provoking consideration unique opportunities former mechanism offers. Accordingly, first part this Perspective article will cover stereoselective alkene operating an emphasis on origin stereocontrol. Next, examples where these employed in tandem subsequent transformations to rapidly form complex molecular architecture be discussed, illustrating potential as strategic tool synthesis.

Language: Английский

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Enantioselective Synthesis of anti-1,2-Oxaborinan-3-enes from Aldehydes and 1,1-Di(boryl)alk-3-enes Using Ruthenium and Chiral Phosphoric Acid Catalysts

Journal of the American Chemical Society, Journal Year: 2017, Volume and Issue: 139(31), P. 10903 - 10908

Published: July 14, 2017

A cationic ruthenium(II) complex catalyzes double-bond transposition of 1,1-di(boryl)alk-3-enes to generate in situ 1,1-di(boryl)alk-2-enes, which then undergo chiral phosphoric acid catalyzed allylation aldehydes producing homoallylic alcohols with a (Z)-vinylboronate moiety. 1,2-Anti stereochemistry is installed an enantioselective manner. The (Z)-geometry forged the products allows their isolation form 1,2-oxaborinan-3-enes, upon further synthetic transformations are operated.

Language: Английский

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Generation and Application of (Diborylmethyl)zinc(II) Species: Access to Enantioenriched gem‐Diborylalkanes by an Asymmetric Allylic Substitution

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(39), P. 12930 - 12934

Published: July 2, 2018

We report the successful generation of (diborylmethyl)zinc(II) species by transmetallation beteween isolable (diborylmethyl)lithium and zinc(II) halide (X=Br, Cl) their application in synthesis enantioenriched gem-diborylalkanes bearing a stereogenic center at β-position diboryl groups an asymmetric allylic substitution reaction. The reaction has broad substrate scope, various can be obtained good yields with excellent enantioselectivity. Further elaboration provides access to diverse set valuable chiral building blocks.

Language: Английский

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Stereoselective Tandem Bis-Electrophile Couplings of Diborylmethane

Journal of the American Chemical Society, Journal Year: 2017, Volume and Issue: 139(40), P. 14061 - 14064

Published: Sept. 22, 2017

A copper-catalyzed three-component linchpin coupling method for the stereoselective union of readily available epoxides and allyl electrophiles is disclosed. Transformations employ [B(pin)]2-methane as a conjunctive reagent, resulting in formation two C–C bonds at single carbon center bearing C(sp3) organoboron functional group. Products are obtained 42–99% yield, up to >20:1 dr. The utility approach highlighted by stereospecific transformations entailing allylation, tandem cross coupling, application synthesis 1,3-polyol motifs.

Language: Английский

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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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An Olefinic 1,2‐Boryl‐Migration Enabled by Radical Addition: Construction ofgem‐Bis(boryl)alkanes

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(28), P. 9448 - 9452

Published: May 6, 2019

A series of in situ formed alkenyl diboronate complexes from Grignard reagents (commercially available or prepared bromides and Mg) with B2 Pin2 (bis(pinacolato)diboron) react diverse alkyl halides by a Ru photocatalyst to give various gem-bis(boryl)alkanes. Alkyl radicals add efficiently the complexes, adduct radical anions undergo radical-polar crossover, specifically, 1,2-boryl-anion shift boron α-carbon sp2 center. This transformation shows good functional-group compatibility can serve as powerful synthetic tool for late-stage functionalization complex compounds. Measurements quantum yield reveal that radical-chain mechanism is operative which diboronates acts reductive quencher excited state photocatalyst.

Language: Английский

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α-Boryl Organometallic Reagents in Catalytic Asymmetric Synthesis

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(16), P. 10660 - 10680

Published: Aug. 12, 2021

Recent years have witnessed an increase in the popularity of α-boryl organometallic reagents as versatile nucleophiles asymmetric synthesis. These compounds been adopted chemo- and stereoselective coupling reactions with a number different electrophiles. The resulting enantioenriched boronic esters can be applied stereospecific carbon-carbon or carbon-heteroatom bond construction reactions, enabling two-step strategy for complex structures high efficiency functional group compatibility. Due to these reasons, tremendous effort has devoted preparation enantiomerically enriched development related racemic prochiral materials. In this review, we describe enantio- diastereoselective that involve starting materials products showcase their synthetic utility.

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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Chemo- and Stereoselective Crotylation of Aldehydes and Cyclic Aldimines with Allylic gem-Diboronate Ester

Organic Letters, Journal Year: 2017, Volume and Issue: 19(15), P. 4054 - 4057

Published: July 19, 2017

We report a highly chemo- and stereoselective crotylation of aldehydes cyclic aldimines with allylic-gem-diboronate ester as new type organoboron reagent. The undergoes the in excellent stereoselectivity, forming anti-5,6-disubstituted oxaborinin-2-ols or (E)-δ-boryl-anti-homoallylic amines high efficiency. reaction shows wide range substrate scope functional group tolerance. synthetic applications obtained products, including stereospecific C–C, C–O, C–Cl bond formation, are also demonstrated.

Language: Английский

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