Direct C(sp<sup>2</sup>)C(sp<sup>3</sup>) Cross‐Coupling of Diaryl Zinc Reagents with Benzylic, Primary, Secondary, and Tertiary Alkyl Halides

Dunsford, Jay J.; Clark, Ewan R.; Ingleson, Michael J.

doi:10.1002/anie.201411403

Cited by 62 publications

(33 citation statements)

References 53 publications

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“…However, adding an equiv of MgCl 2 to this type of arylzinc reagent made the yield significantly increase to 83 % (Table , entry 3). It has been reported that action of ArZnX with MgX 2 led to formation of ionic zincates which have higher reactivity than ArZnX . The role of LiX may involve increasing the solubility of the zinc reagents through forming a trimetallic adduct and producing reactive zincates…”

Section: Optimization Of the Reaction Conditions[a]mentioning

confidence: 78%

“…On the other hand, transition‐metal‐free reactions are attracting more and more attention because they are less costly and more environmentally friendly and can avoid any transition metal impurities in pharmaceutical products . For example, Hayashi et al.…”

Section: Optimization Of the Reaction Conditions[a]mentioning

confidence: 99%

“…carried out direct reaction between arylaluminum compounds and organic halides . Ingleson described transition‐metal‐free reaction of diaryl zinc reagents with alkyl halides . Knochel et al.…”

Section: Optimization Of the Reaction Conditions[a]mentioning

confidence: 99%

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Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Dai

Wang

2017

Chemistry An Asian Journal

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Section: Optimization Of the Reaction Conditions[a]mentioning

confidence: 78%

Section: Optimization Of the Reaction Conditions[a]mentioning

confidence: 99%

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Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Dai

Wang

2017

Chemistry An Asian Journal

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“…Unless otherwise indicated all reagents were purchased from commercial sources and were used without further purification. The zincate, [14] 4-bromo-7-(9,9-dioctyl-9H-fluoren-2-yl)benzo[c] [1,2,5]thiadiazole, [22] Pd(tBu 3 P) 2 , [23] 2-BPh 2 [8] bis(tri-n-butylstannyl)thieno[3,2-b]thiophene [24] were synthesised by modified literature procedures. All appropriate manipulations were performed by using standard Schlenk techniques or in an argon-filled MBraun glovebox (O 2 levels below 0.5 ppm).…”

Section: Methodsmentioning

confidence: 99%

Highly Emissive Far Red/Near‐IR Fluorophores Based on Borylated Fluorene–Benzothiadiazole Donor–Acceptor Materials

Crossley

Vitórica-Yrezábal

Humphries³

et al. 2016

Chemistry A European J

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Stille, Suzuki-Miyaura and Negishi cross-coupling reactions of bromine-functionalised borylated precursors enable the facile, high yielding, synthesis of borylated donor-acceptorm aterialst hat contain electron-rich aromatic units and/or extendede ffective conjugation lengths. These materials have large Stokes shifts, low LUMO energies, small band-gapsa nd significant fluorescencee mission > 700 nm in solution and when dispersed in ahost polymer. IntroductionNear-infrared (NIR) absorbing ande missive molecules have attracted significanti nterest due to potential applications including night-vison displays, sensors and in-vivo imaging. [1,2] Generating organic NIR emitters that have appreciable quantum yields is challenging due to the energy gap law where the emission efficiency reduces with decreasing energy gap. [3] This is exacerbated in the solid state as aggregation often leads to additionaln on-radiative pathways and significant emission quenching. [4] Onee ffective strategy for accessing low-bandgap materials is to construct p-conjugated systems containing donor (D) and acceptor( A) groups. [5] However, D-A materials with appreciable solid state NIR emissiona re currently rare, [2d] therefore new low-band-gap D-A materials are desirable, particularly if accessible by simple modular routes.Another attractive property of D-A materials is the large degree of controlo ver the electronic and optical properties by rational structural modification.F or example, the coordination of aL ewis acid to aL ewis basic site on an acceptorm oiety has been previously used to generate D-A materials with low LUMO energies and small band-gaps. [6] Ar elated approach that generates D-A materials that are more stable to moisture and Lewis bases appendsB R 2 moietiest oac onjugated framework throughf ormationo faC ÀBb ond and ad ative bond from the acceptor to the boronc entre. [7] We have recently utilised this methodology to synthesise borylated 9,9-dioctylfluorene-benzothiadiazole (F8-BT)c ontaining D-A materials by directedelectrophilicb orylation which concomitantly formsaCBa nd aN !Bb ond. [8] This borylation reactionp lanarises the conjugated backboneg eneratingr igid structures with extended effective conjugation lengths.T hese fused materials showed large Stokes shifts, low band-gaps, were stable to H 2 O and O 2 and wereh ighly emissive in solution and the solid state;f or example, F8-BT-F8 functionalised with aB Ph 2 group was highly emissive in the solid state (PLQY3 3% with l max = 696 nm). [8] Whilst notable it is desirable to develop synthetic routest or apidly access analogues with lower band-gapst hat were highly emissive in the solids tate with emissionf urther into the NIR (l max @ 700 nm).As imple approacht od eliver these materials is to introduce more electron-rich donor units than F8 and/or to extend the effective conjugation length.H owever,c oupling other donor units to F8-BT generates unsymmetric F8-BT-D materials that complicates the electrophilic borylation step, particularly wheree lectr...

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“…In agreement with Lemaire's work, this study also stresses that the success of the coupling heavily depends on the use of non-polar, non-coordinating solvents. [6] Thus, the presence of ethereal solvents such as THF or Et2O dramatically slows down the reactions,. [6] While these results illustrate the ability of arylzinc reagents to engage in cross-coupling without the need of transition-metal catalysis, no mechanistic information is available on how these reactions actually occur.…”

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confidence: 99%

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature

et al. 2018

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Pairing a range of bis(aryl) zinc reagents ZnAr2 with the stronger Lewis acidic [(ZnAr F 2)] (Ar F = C6F5), enables highly stereoselective cross-coupling between glycosyl bromides and ZnAr2 without the use of a transition metal. Reactions occur at room temperature with excellent levels of stereoselectivity, where ZnAr F 2acts as a non-coupling partner although its presence is crucial for the execution of the C(sp 2 )-C(sp 3 ) bond formation process.Mechanistic studies have uncovered a unique synergistic partnership between the two zinc reagents, which circumvents the need for transition-metal catalysis or forcing reaction conditions. Key to the success of the coupling is the avoidance of solvents that act as Lewis bases vs. diarylzinc compounds (e.g. THF).

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Direct C(sp²)C(sp³) Cross‐Coupling of Diaryl Zinc Reagents with Benzylic, Primary, Secondary, and Tertiary Alkyl Halides

Cited by 62 publications

References 53 publications

Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Highly Emissive Far Red/Near‐IR Fluorophores Based on Borylated Fluorene–Benzothiadiazole Donor–Acceptor Materials

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature

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Direct C(sp2)C(sp3) Cross‐Coupling of Diaryl Zinc Reagents with Benzylic, Primary, Secondary, and Tertiary Alkyl Halides

Cited by 62 publications

References 53 publications

Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Transition‐Metal‐Free Reaction of Aryltrimethylammonium Iodides with Arylzinc Reagents

Highly Emissive Far Red/Near‐IR Fluorophores Based on Borylated Fluorene–Benzothiadiazole Donor–Acceptor Materials

Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature

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Direct C(sp²)C(sp³) Cross‐Coupling of Diaryl Zinc Reagents with Benzylic, Primary, Secondary, and Tertiary Alkyl Halides