Regio‐ und chemoselektive Metallierung von Arenen und Heteroarenen mit gehinderten Metallamidbasen

Haag, Benjamin A.; Mosrin, Marc; Ila, H.; Malakhov, Vladimir; Knöchel, Paul

doi:10.1002/ange.201101960

Cited by 135 publications

(13 citation statements)

References 390 publications

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“…In conclusion, we reported a novel method for the preparation of highly substituted arenes [16] starting from readily available benzoic acid derivatives. The sequence consists of an alkylative Birch reduction, allylic cyclohexadiene alkylation, decarboxylative g-arylation, and rearomatization.…”

Section: Angewandte Communicationsmentioning

confidence: 99%

Regioselective Threefold Aromatic Substitution of Benzoic Acid Derivatives by Dearomatization, Regioselective Functionalization, and Rearomatization

Koch

Studer

2013

Angew Chem Int Ed

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Section: Angewandte Communicationsmentioning

confidence: 99%

Regioselective Threefold Aromatic Substitution of Benzoic Acid Derivatives by Dearomatization, Regioselective Functionalization, and Rearomatization

Koch

Studer

2013

Angew Chem Int Ed

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“…On the contrary, TMPMgCl·LiCl has a monomeric structure and can be handled as a 1.2 M solution in THF [29]. The improved kinetic basicity of this reagent allows the selective magnesiation of oligofunctional compounds (Scheme 5.4) [30]. As EtO a consequence of improved basicity, the magnesiation can be conducted at low temperature, and this enables the preparation of functional organomagnesium compounds derived from electrophilic heterocycles known to undergo nucleophilic attack by organometallics, as showcased with 28 [29] or 31 [31] (Scheme 5.4).…”

Section: Direct Magnesiation Reactionsmentioning

confidence: 99%

“…However, some aromatic substrates bearing electrondonating groups or weakly electron-withdrawing groups only react sluggishly at low temperature. The use of the stronger base bis-TMP-magnesium (TMP 2 Mg·2LiCl) (TMP, 2,2,6,6-tetramethylpiperidyl) allows their efficient magnesiation [30,32]. This is, for example, the case for the preparation of 34 [33] derived from an arene having both an iodide and a phosphoramidite substituent.…”

Section: Direct Magnesiation Reactionsmentioning

confidence: 99%

Carbon–Carbon‐Bond‐Forming Reactions Mediated by Organomagnesium Reagents

Chemla

Ferreira

Pérez‐Luna

et al. 2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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IntroductionFirst reported at the beginning of the twentieth century [1], organomagnesiums are very important synthetic tools. In the field of coupling reactions, first examples of transition-metal-mediated reactions have been reported by Gilman and Lichtenwalter [2] with the oxidative homo-coupling of aryl Grignard reagents in the presence of transition metal halides as both catalyst precursors and oxidants. This reaction was later greatly improved by Kharasch [3], who showed that an efficient homo-coupling reaction could be observed with a small amount of CoCl 2 (3 mol%) and an organic halide as a stoichiometric oxidant. This breakthrough was then followed by the report in 1941 on cross-coupling reactions of arylmagnesium bromides with vinylic halides in the presence of various transition metal salts by the same group [4]. Surprisingly, this seminal work remained mainly unexploited, until this reaction was reinvestigated by several groups in the beginning of the 1970s [5]. Thus, Kochi and Tamura [6, 7] described in 1971 the use of Fe(III) salts as catalyst precursors for cross-coupling reactions, while Kumada [8] and Corriu [9] reported the use of nickel for similar transformations [10,11]. At the same time, the group of Normant [12] described the Cu-catalyzed reaction of the Grignard reagents with organic halides, followed by the report of Murahashi [13] on the use of palladium as a catalyst in similar cross-couplings. Most cross-coupling reactions have been performed with unfunctionalized Grignard reagents because no general method for preparing oligofunctional organomagnesium reagents was available. However, the situation is rapidly evolving, thanks to the groundbreaking work of Knochel and coworkers [14] on the preparation of highly functionalized Grignard reagents. In this chapter, the scope and limitations of cross-coupling reactions involving organomagnesium reagents are showcased with select examples from the recent literature with a special focus on functional-group-tolerant procedures. The recent developments of the most challenging transformations including either the use of oligofunctional metallic species or β-hydrogen-containing nucleophiles will be specially highlighted.

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“…[1,2] Ty pically,o rganolithium/magnesium reagents and lithium/magnesium amides are employed as the metalating reagents of choice,w hereas organo-and inorganic sodium reagents have rarely been utilized for metalation because of their instability,i naccessibility,a nd limited reactivity despite the lower cost of metallic sodium and its derivatives. [1,2] Ty pically,o rganolithium/magnesium reagents and lithium/magnesium amides are employed as the metalating reagents of choice,w hereas organo-and inorganic sodium reagents have rarely been utilized for metalation because of their instability,i naccessibility,a nd limited reactivity despite the lower cost of metallic sodium and its derivatives.…”

mentioning

confidence: 99%