Funktionalisierung von Aryllithium‐Regioisomerengemischen durch selektive Abfangreaktionen mit Zirconocendichlorid

Castelló-Micó, Alicia; Herbert, Simon; León, Thierry; Bein, Thomas; Knöchel, Paul

doi:10.1002/ange.201508719

Cited by 4 publications

(2 citation statements)

References 46 publications

(8 reference statements)

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“…The expected 1,2-diketo derivatives were then obtained by using a TBAF to cleave the silyl protecting group, which was followed by amination with ethylenediamine at 80 °C. In a two-step synthesis, DDQ-mediated aromatization was used to synthesise pyridine-pyrazine core 85 in 32 % yield (Scheme 19). [85] A practical method for a direct ortho magnesiation of trifluoroacetamides of aminopyridines 86, in the presence of Grignard reagents (MeMgCl) at room temperature was performed with TMPMgCl • LiCl by Knochel group. These ortho selective metalations are compatible with several carbonyl amide functionalities 86 with the addition of various electrophiles (C 2 Cl 4 Br 2 , ArÀ X) in the presence or absence of Pdcatalyst and permit leading to poly substituted aminopyridine scaffolds 88-90 in good yields up to 80 %, obtained results are cited in Scheme 20.…”

Section: Functionalization Of Pyridine and Quinoline Scaffolds Enable...mentioning

confidence: 99%

Functionalization of Pyridine and Quinoline Scaffolds by Using Organometallic Li‐, Mg‐ and Zn‐Reagents

Dhayalan¹,

Sharma

Chatterjee

et al. 2023

Eur J Org Chem

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This Review discusses the various methods for functionalizing pyridine and quinoline scaffolds, including direct selective metalation (DoM), halogen/metal exchange reactions, Li, Mg, and Zn insertion, and trans‐metalation approaches, which are then followed by cross‐coupling reactions of the Kumada or Negishi types. Selective deprotonation of aryl or pyridyl/quinolinyl derivatives can be performed using n‐BuLi, LDA, and TMP‐based different organolithium, ‐magnesium, and ‐zinc reagents. The functionalized pyridine and quinoline‐based heterocyclic compounds were prepared by selectively deprotonating with presenting a directing functional group substituted pyridine/quinoline analogues in the presence of TMP‐bases (TMP−Li, Mg, Zn reagents). Different aryl or alkyl Li, Mg, and Zn reagents with electron‐donating and electron‐withdrawing substituents undergo transition metal‐catalyzed C(sp2)−C(sp2) and C(sp2)−C(sp3) types of cross‐coupling reactions with pyridine/quinoline halides under mild conditions with the sustainable process producing complex N‐heterocycles. Using moderate and sustainable reaction conditions, sensitive functional group tolerance, and inexpensive and low toxic chemicals, highly functionalization of pyridine and quinoline‐based bioactive therapeutic scaffolds and natural products was accomplished. Therefore, in this article, we provide a succinct overview of the numerous synthetic strategies and practical methods used by various authors between 2010 and 2023 to functionalize pyridine and quinoline analogues using diverse Li, Mg, and Zn organometallic reagents.

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Section: Functionalization Of Pyridine and Quinoline Scaffolds Enable...mentioning

confidence: 99%

Functionalization of Pyridine and Quinoline Scaffolds by Using Organometallic Li‐, Mg‐ and Zn‐Reagents

Dhayalan¹,

Sharma

Chatterjee

et al. 2023

Eur J Org Chem

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“…peridine (TMPH) were selected as substrates. Ph 2 NH, HMDS, and PhNH 2 due to their lower pK a (25, 30, and 31, respectively, in DMSO) [59] and TMPH due to its broad application in synthesis (Knochel-Hauser base, pK a = 37 in DMSO) [47,[59][60][61][62][63][64][65][66][67][68][69]. Excellent yields were obtained: HMDSMgCl⋅LiCl 1.15 M (98%), Ph 2 NMgCl⋅LiCl 1.16 M (97%), and PhNHMgCl⋅LiCl (1.15 M, 96%, Table 4, entries 1-3).…”

Section: Knochel-hauser Bases Via Stratified Packed-bed Columns Conta...mentioning

confidence: 99%

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

Berton

Sheehan

Adamo

et al. 2020

Beilstein J. Org. Chem.

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Magnesium organometallic reagents occupy a central position in organic synthesis. The freshness of these compounds is the key for achieving a high conversion and reproducible results. Common methods for the synthesis of Grignard reagents from metallic magnesium present safety issues and exhibit a batch-to-batch variability. Tubular reactors of solid reagents combined with solution-phase reagents enable the continuous-flow preparation of organomagnesium reagents. The use of stratified packed-bed columns of magnesium metal and lithium chloride for the synthesis of highly concentrated turbo Grignards is reported. A low-cost pod-style synthesizer prototype, which incorporates single-use prepacked perfluorinated cartridges and bags of reagents for the automated on-demand lab-scale synthesis of carbon, nitrogen, and oxygen turbo magnesium bases is presented. This concept will provide access to fresh organomagnesium reagents on a discovery scale and will do so independent from the operator’s experience in flow and/or organometallic chemistry.

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LiTMP Trans‐Metal‐Trapping of Fluorinated Aromatic Molecules: A Comparative Study of Aluminum and Gallium Carbanion Traps

et al. 2017

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Fluoroaromatic scaffolds pose ac hallenge to lithiation due to low stability of lithiated intermediates.H ere we apply trans-metal-trapping (TMT) to as eries of key fluorinated aromatics.I nT MT,L iTMP performs the metalation, while an organometallic trap intercepts the emergent carbanion. This study contrasts the trapping abilities of iBu 2 AlTMP and Ga(CH 2 SiMe 3 ) 3 ,s tructurally mapping their TMT reactions and probing relative stabilities of metalated fluoroaromatic intermediates by NMR studies.R esults show the installed AlÀC(aryl) bonds are more prone to decomposition by benzyne formation and Li-F liberation, than the Ga À C(aryl) species.T he latter are thus better for onward reactivity as demonstrated in cross-coupling reactions with benzoyl chloride that produce ketones.

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Funktionalisierung von Aryllithium‐Regioisomerengemischen durch selektive Abfangreaktionen mit Zirconocendichlorid

Cited by 4 publications

References 46 publications

Functionalization of Pyridine and Quinoline Scaffolds by Using Organometallic Li‐, Mg‐ and Zn‐Reagents

Functionalization of Pyridine and Quinoline Scaffolds by Using Organometallic Li‐, Mg‐ and Zn‐Reagents

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

LiTMP Trans‐Metal‐Trapping of Fluorinated Aromatic Molecules: A Comparative Study of Aluminum and Gallium Carbanion Traps

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